Vasectomy in the male dog

Vasectomy is a procedure used for sterilization that entails removing a small section of the vas deferens (the tube that carries sperm from the testicle to the urethra, during ejaculation).  This is a technical surgery that requires accurate knowledge of the anatomy of the spermatic cord and meticulous attention to detail. If the wrong tissue is removed or too small a portion is removed, fertility may remain or may return at some time after surgery.  After vasectomy is performed, testosterone levels will remain the same, along with all other male traits (drive, interest in breeding, male behaviors). Sperm production is also maintained, it is just that the sperm cannot get out of the testicle to the urethra.

Vasectomy sites can sometimes recanalate restoring flow of sperm through the urethra. Recanalization of the vas occurs in almost 2% of human vasectomies overall (early or late combined), the species where the procedure is done most. In cattle and sheep, between 1- 5% recanalate, either early or late.

Complications of vasectomy include sperm granuloma formation which can cause pain in the scrotum requiring a second, more difficult surgery to remove them or development of tumors at the ends of the vasectomy site, which are usually benign but can become malignant if not noticed early in their development.  Hemorrhage into the scrotum and infection of the surgery sites may also develop, requiring treatment.

Vasectomized dogs are just like intact dogs in all behaviors (desire to breed, roam, potential for aggressive behavior) and their ability to transmit disease (Brucella, herpesvirus, transmissible venereal tumor). Any owner that has a vasectomized dog must be responsible enough to control these behaviors exactly the same as an intact male. Even if they are sterile, they can and will still actively seek out and breed bitches. A possible concern for owners of vasectomized dogs is that after the procedure is performed they may relax their handling behaviors, perhaps allowing an accidental breeding to occur. Not only can this transmit disease between the male and female (brucellosis or herpesvirus) but if recanalization has occurred it may result in pregnancy as well.

For the above mentioned reasons, it is this author’s recommendation, that if owners want their dogs to have exposure to gonadal steroids for a few years to gain their benefits, they should just leave the dog intact for 3-5 years, treat him like an intact male with all the protections that go with it, and then neuter him.  After 3-5 years, there are more down sides (benign prostatic hyperplasia, prostatitis, perianal adenoma formation, testicular tumors), to being intact than benefits.

Courtesy of Dr Cheryl Lopate of REPRODUCTIVE REVOLUTIONS

Supplements that May Potentially Improve Sperm Quality

Drug and Nutritional supplements that may be indicated to improve fertility in the valuable stud dog:

There are a handful of drugs and nutritional supplements that may have application.

Avoid testosterone, female hormones, anabolic steroids, corticosteroids and chemotherapeutic drugs unless there is significant health benefit and they are prescribed by a veterinarian.

The following drugs MAY be indicated and prescribed by a veterinarian to improve male


  1. Antibiotics for evidence of prostate or urinary tract infection.
  2. Antibiotics if mycoplasma is suggested.
  3. Thyroid therapy if thyroid testing suggests supplementation is indicated.
  4. Medications to reduce the size of the prostate if benign prostatic hypertrophy is suspected

or has been diagnosed. These drugs include megestrol acetate and finasteride.

The following supplements have been suggested based on anecdotal evidence to improve male fertility:


This is the most common nutraceutical category used for improving sperm quantity and quality. It is found in many formulations by many manufacturers. Many, like International Canine Semen Bank’s CF- PlusR, contain perna (green-lipped) mussels as the primary active ingredient. Anecdotal reports suggest improve semen quality in bulls, horses, and dogs. The theory of the mechanism, according to Dr. Roger Kendall is enhanced cellular reactions and amino acid uptake. There is no documentation to support the use of this product in the dog. The dosage for this application has not been determined; there are dosage regimens for the use of these products for other purposes such as improving joint mobility. Unless there is an allergic response, it is unlikely this product would cause any harmful side effects.

  1. Anti-oxidants.

These typically include Vitamins C, E, beta carotene, and selenium among others. These are available from many manufacturers over-the-counter. They appear to act by removing free radicals, thus protecting the cells. In addition, greater sperm numbers in the ejaculate have been reported. There is no documentation to support the use of this product. There are anecdotal reports that semen concentrations are improved, that there are fewer head and acrosomal abnormalities when used, and semen tolerates cooling and freezing better when patients are on this type of product. Some components can be harmful if used in excess, so care should be taken when this is prescribed.

  1. Fatty Acid supplements.

These are available from many manufacturers over-the-counter. The reports indicate anecdotally that there is improvement in semen morphology when the dog has a high percentage of proximal droplets.

  1. L-Carnitine.

This nutritional supplement alters fat metabolism. This is available from several manufacturers and is found in some senior dog diets. Anecdotally, it has been reported to improve sperm motility. The mechanism of action has not been determined. It is included in some commercially available dog foods to aid in weight loss so should be used with care to avoid excessive weight loss in the patient. The components and ratio of omega 3 to 6 fatty acids should be assessed to ensure it is found in an anti-inflammatory ratio.

Courtesy of Dr Marty Greer of Veterinary Village , Lomira WI

Recommendations for the Stud Dog

In actively breeding males, it is recommended that semen be comprehensively evaluated every 2 – 4 months at a minimum.  In this way, any change in the status of the ejaculate will be detected early.  In males that are not being used actively, it is recommended that semen be evaluated just prior to the onset of the bitch’s season during which breeding will occur or at the very start of the bitch’s cycle.  In this way one can feel relatively confident that semen quality will be adequate for the upcoming breeding.  If chilled semen is to be used for the first time, a longevity exam is recommended to ensure the semen will ship adequately.

A small number of males may benefit from a clean-out collection in the week prior to anticipated breeding but most males clean out old sperm on a daily basis, so this isn’t necessary. If the male has a history of the first collection being poor and subsequent collections having improved motility or morphology, a clean-out collection should be performed.   Any deterioration in semen quality or a change in fertility (decreased litter size or pregnancy rates) should instigate further investigation as to the cause of the change.

Males should not be collected or bred more often than every other day on a regular basis.  If the dog has more than one bitch to breed in a week, then ovulation timing should be performed to ensure the breedings are performed at the optimal time for each bitch. If it is optimal to breed both bitches on the same day and sperm numbers and semen quality allows, the ejaculates can be split and a minimum breeding dose sent or inseminated into to each bitch to be bred.  Utilizing advanced reproductive techniques such as transcervical or surgical insemination can reduce the breeding dose required for each bitch and will maximize use of the dog.

If absolutely necessary, a male can be collected daily for 3 – 5 days in a row (depending on the male’s daily sperm output) without completely depleting sperm stores. It is better not to do more than one natural breeding daily unless it has been determined that there are adequate sperm numbers to do this. In most cases, collecting a dog twice in one day results in about ½ the number of sperm in the second collection than was in the first collection. So, a dog with average sperm number would provide an adequate dose to the first bitch bred, but not to the second. As a general rule of thumb, males with increased scrotal width and normal semen characteristics will have more sperm reserves than those with smaller total scrotal width.  This means that toy and small breed dogs will deplete their sperm numbers with fewer daily collections (3 days in a row) than will males of the larger breeds (5 days in a row).  If the male is not allowed a day of rest between regular collections, sperm numbers may decrease enough to affect pregnancy rates and litter size.

Collection and storage of frozen semen can alleviate the stress of overuse in popular males.  Semen evaluation and post thaw testing, should be performed every time the semen is frozen; and results of both pre- and post-thaw testing should be provided to the bitch owner, along with any fertility information available from previous breedings.  Number of breeding doses per ejaculate varies with the male (sperm numbers and semen quality) and may range from <1 – 10+ doses/ejaculate.  Again, males with greater total scrotal width tend to have more breeding doses/ejaculate, assuming semen quality is good.   Males with any type of prostatic disease are poor candidates for semen freezing and should have their prostatic disease treated prior to freezing.  Any male that seems to have good quality semen pre-freeze that has poor quality semen post-thaw, should be evaluated for prostate disease and if none is found, then a different extender should be used on the next attempt.

Owners should ensure that their freezing facility is providing an adequate breeding dose when preparing frozen semen. For toy, small and medium breeds, a minimum of 100- 125 million normal, motile sperm is ideal; while for large and giant breeds, a minimum of 150 – 200 million normal, motile sperm is recommended. With the investment involved for the bitch owner in a frozen breeding, ensuring that adequate sperm numbers of normal motile sperm are available will maximize chances of normal pregnancy rates and litter size. The dog owner can request a minimum breeding dose be prepared and provide the number of normal, motile sperm desired in each dose to the freezing facility prior to the actual freeze.

Brucellosis testing is recommended prior to each breeding if dogs are used infrequently, regardless of the type of breeding being performed.  Brucellosis can be transmitted either by mucosal contact (aerosol or oral/nasal contact with infected urine or vaginal secrections) or venereally. So, a male that has never been bred before can still be positive. Males that are being bred frequently (more than once every 2 months) should be tested every 2-3 months. All males should have their prostate examined per rectum (and by ultrasound if abnormal) and have a comprehensive physical examination including complete blood count, serum chemistry and thyroid screening (for autoantibodies) yearly.  Other vaccinations should be determined following discussion with your regular veterinarian.  Dogs should be dewormed at least annually and specific deworming programs should be tailored to the individual dog’s needs and the kennel situation.

Courtesy of Dr Cheryl Lopate of REPRODUCTIVE REVOLUTIONS

Frozen Semen FAQ

Why Have Semen Frozen?

Long Term Storage – If your stud has positive enduring qualities which should be preserved for the breed or your own future breeding program, you should have his semen frozen. This will guarantee his breeding availability for future generations.

            For Breedings When The Stud Is Not Available – There are times when the stud dog is not available when an individual bitch needs to be bred. The reason may be due to a show or trial schedule, booked stud services, temporary illness or injury or any other logistical scheduling conflict that could limit a stud’s availability.

            Long distance and international breeding – long distance breedings may be accomplished without shipping either the bitch or stud dog by using either chilled/extended or frozen semen.


How is semen collected?

            Semen is collected from the stud dog by manual stimulation. The different parts, or fractions, of the ejaculate are collected separately so that good quality sperm-rich semen is frozen and stored. In general, semen of best quality and higher counts are collected when the stud dog’s libido is high. We try to simulate a typical breeding situation for each stud and encourage owners to provide a bitch in heat to use as a “teaser”. In addition, if the stud dog associates a particular item with breeding, such as a rug, table, breeding rack, etc., that item may be helpful and should be brought to the appointment. If appropriate, we may recommend an injection that is temporary and without lasting effects to help increase libido. It is often recommended to wait for a teaser prior to scheduling a frozen semen collection appointment unless times constraints exist.


What happens after the semen is collected?

            Immediately after the collection, the semen is evaluated microscopically. If the quality is acceptable for freezing, the sample is then extended with a buffer solution that protects the cells during freezing and thawing. A sperm count is performed and the sample is further diluted into a uniform concentration. The diluted semen sample is the divided into multiple individually labeled straws – the number of straws is determined by the initial sperm count. After a gradual cooling and freezing process, one “partial” straw is thawed and examined for motility and quality. Average post thaw motility is 40-60% – this means that 40-60% of the original sperm cells shave survived the freeze and thaw process.


How long does the collection and freeze process take?

            Typically the entire process takes 3-4 hours from the time of the collection. However, clients need only be present for the collection process which make take 15-30 minutes. Additional time may be required in the office as all appropriate paperwork needs to be complete at the time of the collection.


How and where is the frozen semen stored?

            Frozen semen is sorted permanently within our facility in a specialized insulated container called a dewar that contains liquid nitrogen. The frozen semen is help in liquid nitrogen vapors at a temperature of -196 degrees centigrade or approximately 300 degrees below zero Fahrenheit. This temperature is maintained and keeps the semen viable indefinitely. Since the container does not require electricity, there is no fear of accidental thawing due to a power failure. We are an approved permanent storage facility for all AKC breeds and most other registration bodies.


How much semen will be stored from each collection?

            The number of straws stored is directly dependant on your stud dog’s sperm count. The quantity and quality of the semen produced in one ejaculate can vary, sometimes considerably in a short period of time from dog to dog and collection to collection. Factors that can affect your stud’s semen quality include:

Age: in general, a young mature dog (2-4 years of age) will have a higher sperm count and better quality semen than older or immature dogs.

General Health Status: An ill or stressed dog will rarely produce good quality semen. It can take as long as 3-6 months following recovery from illness or marked stress for the ejaculate to return to normal. Some medications, both prescription and over the counter, can affect sperm production.

Size: in general, large breeds produce more sperm cells than smaller breeds. Toy breeds will often need to have semen collections done several times to store enough sperm to breed one bitch, whereas a large or giant breed might produce enough sperm in one collection to inseminate multiple bitches. It is the number of sperm cells, not the volume of the collection that is important.

Disposition and Temperament: in general, an experience stud dog produces better semen quality than one who doesn’t fully understand the collection process and what

is expected of him. It may be advisable to have a young or inexperienced dog collected once or twice prior to having semen stored in order to acclimate him to the process. If a stud dog is shy or nervous, his semen numbers may be poor and preclude freezing and storing the collection. In addition, a dog that is accustomed to having people around and being handled while breeding will fare better when having semen collected. We strive to simulate a natural breeding for a frozen semen collection attempt – a bitch in heat standing in front of the stud dog assist the collection process.


Is it worthwhile to attempt semen freezing with an unproven stud?…. an older stud?… an ill dog?

            If a dog is producing motile sperm cells, it is useful to attempt to freeze his semen. Generally, if semen numbers and /or quality are compromised, only a small quantity of viable sperm cells will be stored. While this will give you an “insurance policy” bank of semen, every attempt should be made to either breed your stud with fresh semen or improve semen quality and freeze subsequent collections.


What kind of paperwork and record keeping are necessary?

            A copy of the stud’s individual registration papers and positive identification including microchip or tattoo and current photos are usually required. The stud owner’s signature must be obtained so that we may file appropriate paperwork with the stud dog’s registration body. After the semen is collected and stored, the stud dog owner will receive written information regarding the collection statistics and a yearly storage bill.


What is the success rate for a breeding with frozen semen?

            Individual success will vary depending on the semen quality, bitch fertility and procedures used for the breeding. Parameters exist for the appropriate use of frozen semen for a breeding and should be investigated in advance of a bitch’s heat cycle.

Fertility Evaluation in the Stud Dog

The normal male dog attains puberty at approximately 6 – 8 months of age.  Sexual maturity is generally attained at 18 – 30 months.  Males may successfully breed bitches prior to sexual maturity but they will not attain maximal fertility or daily sperm output until mature.  The normal male can breed once every 2 – 5 days and maintain adequate sperm numbers.

A complete fertility evaluation in the male involves history, physical examination, libido determination, semen collection and evaluation, hormonal evaluation, and prostatic examination.  The initial database should include a detailed history, a complete physical examination, complete blood count, serum chemistry and urinalysis.  History should include travel, diet, past or current illnesses, medications, vaccinations, deworming history and prior laboratory tests.  Details of breeding history should be obtained, including the dates of all known matings, type of breeding (natural vs. AI – vaginal, transcervical or surgical; fresh, chilled or frozen semen) and the results of these matings (including pregnancy rates and litter size).  Breeding management of each bitch should also be described.

Physical examination of all body systems should be performed with careful examination of the skin, eyes, heart, lungs, abdomen and musculoskeletal system. Following a complete physical examination, a complete reproductive system examination should be performed, including palpation of the scrotal contents, examination of the penis and prepuce and palpation of prostate per rectum.  Serology for Brucellosis should be obtained.

The scrotal skin should be evaluated for any thickening, signs of infection or accumulation of fluid within the sac.  Both testes should be palpated for size, consistency and presence of any masses.  The total scrotal width can be measured with calipers or by ultrasound examination.  Testicular volume can be determined by measuring length, width and height of the testes via ultrasound. The epididymides (the tubules in which the sperm mature before being transported to the vas deferens) and spermatic cords (vas deferens and testicular artery and vein) should be palpated for any thickenings, enlargements, pain (due to inflammation or granuloma [sperm plugs]), or missing segments (aplasia).  Ultrasound examination can further be used to visualize the testes, epididymides and spermatic cords for masses, signs of inflammation, or abnormal fluid accumulations.

The penis should be evaluated for the presence of a persistent frenulum (remnant of skin securing the tip of the penis to the prepuce which normally breaks down around the time of puberty), signs of inflammation, abnormal discharge, reddening, or the presence of any masses.  Rectal palpation of the prostate should be performed (may be completed prior to and/or after semen collection).  The prostate should be located within the pelvic canal and should be small and symmetrical.  In some cases upward pressure may be applied to the abdomen to push the prostate further backward such that it can be palpated in its entirety.  Enlargement (either symmetrical or asymmetrical) of the prostate should instigate further investigation as to the cause.  X-rays of the abdomen may help determine the size and location of the prostate if it cannot be palpated completely per rectum. Ultrasound examination of the prostate may reveal masses, cysts (either within or outside the prostate), inflammation, abscesses or generalized enlargement.  Prostatic fluid can be evaluated either after semen collection or following prostatic massage or wash (if the male cannot be successfully collected).

Semen collection should be performed in the presence of an teaser bitch in heat (estrus) whenever possible.  If a teaser bitch is not available, some males can be stimulated to erection using estrus bitch vaginal swabs or urine, or commercially available pheromone, applied to cotton balls or the vulva of a non-cycling bitch.  Some males may not require any external stimulus beyond manual massage to attain erection.   During collection the male should be observed for ease at which he develops an erection, presence of a normal erection, normal thrusting behavior and normal pulsation associated with ejaculation and prostatic fluid emission.  Semen is ejaculated in 3 fractions: 1) pre-sperm – which arises from the prostate and urethral glands, thought to cleanse the urethra of contaminants (urine, bacteria and smegma) prior to ejaculation; 2) sperm-rich – which arises from the epididymal stores and vas deferens; 3) prostatic secretions – which provides volume to the ejaculate, assists in pushing the sperm out of the vagina, through the cervix, and into the uterus, and provide nutrients for the sperm while traveling to the oviducts.  Semen should be collected in fractions whenever possible to facilitate evaluation of each portion of the ejaculate.  The pre-sperm fraction is clear in color, is usually minimal in volume (less than 5 ml) and is not usually collected.  The sperm rich fraction is white – cloudy white in color and usually 0.5 – 4 ml in volume.  The prostatic fluid is normally clear in color and may range in volume from 3 – 80 ml.   Following collection, it is important to be sure that the erection subsides, that the penis is drawn back into the prepuce and that the prepuce does not roll inwardly when this occurs.

Once the semen is collected, all equipment contacting it should be maintained at 37°C either until insemination or it is properly extended.  Routine semen evaluation includes measurement of semen volume, semen motility, semen concentration, evaluation of individual sperm morphology (shape and form), and sometimes determination of the pH of the ejaculate.  Semen volume is measured in milliliters.  There is no minimal accepted semen volume since it depends on how well fractionated the ejaculate is and how much of each of the fractions is collected.

Semen motility is assessed by placing a drop of raw semen on a pre-warmed microscope slide and applying a pre-warmed coverslip.  Semen is then examined at high and low magnification (i.e. 10x and 40x). A regular light microscope can be used, but the use of a phase contrast microscope enhances the ability to visualize individual sperm movements.  Both total and progressive motility are determined and expressed as a percentage of 100.  Total motility is defined as the percent of sperm that are moving, while progressive motility is defined as the percent of sperm that are moving forward, progressively.  Of the two, progressive motility is most important in determining the number of sperm potentially able to fertilize the oocytes (eggs).  During motility assessment, sperm velocity is also assessed.  Velocity of forward movement is rated on a scale of 0 – 5 (0 = no movement, 5 = rapid, forward movement).  A normal ejaculate contains a minimum of 70% progressively motile sperm.

Semen concentration is measured in millions of spermatozoa per milliliter of semen.  Semen concentration and daily sperm output are directly related to testicular volume.  So, the larger the testicles, the greater the daily sperm output and total sperm/ejaculate should be.   Concentration is typically determined by obtaining a manual count.  A small volume of semen (20 microliters) is added to a known volume of formalin based fluid which kills the sperm (to arrest motility and allow for accurate counting) and causes any red blood cells in the ejaculate to be destroyed so they do not interfere with the count.  A known volume of this fluid is applied to a counting chamber, called a hemacytometer.  Using the counting chamber’s grid and a microscope, the number of sperm in a certain area is counted to determine the concentration per milliliter of semen.  There are some automated sperm counters available but care must be taken to purchase a unit that is calibrated for dog semen.  A normal ejaculate contains a minimum of 200 million spermatozoa/ejaculate.  On average acceptable numbers of total sperm/ejaculate will be from 200 – 300 million for toy breeds; from 200 – 500 million for small breeds; from 400 – 800 million for medium breeds; from 500 million – 1.5 billion for large breeds; and from 600 million – 2 billion for giant breeds.

Individual sperm should be examined (for normal shape and structure) after staining the raw semen.  The most common stain used is eosin-nigrosin.  This stain is a vital stain, which means that it stains the live and dead sperm different colors.  The sperm is divided into 3 segments: head, midpiece and tail.  The head contains the DNA and has a cap (the acrosome) which contains the enzymes that allow fertilization to occur.  The midpiece contains the motor apparatus that propels the sperm.  The tail provides the propulsion to move the sperm forward.  Defects may be classified in several different fashions: primary vs. secondary defects (primary occurring in the testicles, and secondary occurring during storage, transport or handling); major vs. minor (major affecting the ability of the sperm to fertilize and minor not affecting the ability to fertilize) or compensable and non-compensable (compensable defects can be overcome by providing access of the sperm to the egg and non-compensable defects cannot be overcome by the sheer presence of providing access to the egg).  Primary vs. secondary is the most common classification scheme used.  A normal ejaculate contains >70% normal sperm.

Sperm may also be examined to assess for the presence of a normal acrosome using special stains.  These stains differentially stain the DNA portion of the sperm head a different color than the acrosome.  In some cases of infertility, the acrosomes may have already reacted prior to the sperm reaching the oviducts.  If this occurs these sperm will be incapable of fertilizing the eggs when they reach the oviducts.  The semen may also be stained with Wright – Giemsa stain to assess for the presence of white blood cells or germ cells (immature sperm cells shed by the testicle when testicular degeneration is present).  Semen culture may be submitted if high numbers of white blood cells are present in the ejaculate.  Culture for aerobic bacteria and Mycoplasma are commonly obtained.

The pH of the prostatic fluid is usually 6.3 – 6.7.  Either a combination of fraction 2 and 3 or fraction 3 alone can be tested.  Alterations in pH may affect sperm longevity and motility.  Increases or decreases in prostatic fluid pH are common with prostatic disease.  Increases in pH may occur with use of excessive amounts of lubricant or improper cleaning and disinfection of collection equipment.

When semen will be chilled and shipped for insemination, assessment of sperm longevity may be evaluated (following extension with semen extender), in order to determine the potential success with the use of this type of semen.  Semen is collected and extended depending on the semen concentration, the type of extender being used and the type of insemination being performed.  Generally, an ejaculate will be extended at a minimum ratio of 2-3:1.  Semen should be chilled (slowly) to 4 – 5°C and held for a minimum of 48 hours at this temperature.  A small sample of the semen is warmed to 37°C at 24 and 48 hours and total motility, progressive motility and velocity are determined.  In some cases, motility may be so good at 48 hours to make evaluation at 72 and 96 hours (or longer) indicated.

In certain cases, where fertility issues are evident based on pregnancy rates but are not evident based on normal fertility examination, advanced testing may be dictated.  This may include hormonal evaluation, karyotyping, testicular aspiration or biopsy, sperm chromatin structure assay, electron microscopy, HOST (hypo-osmotic swelling test) and acrosomal integrity tests.

Hormones that may be evaluated include testosterone, estrogen, prolactin, LH (luteinizing hormone), FSH (follicle stimulating hormone), and thyroid hormones.  Dogs with testicular degeneration may have elevated estrogen concentrations and decreased testosterone concentrations.  They may also have elevated FSH and LH concentrations.  Prolactin concentrations may be increased or decreased depending on normal pituitary (brain) function and feedback from the testes.  Thyroid hormones are commonly assessed when faced with infertility problems.  There is little direct evidence to substantiate that hypothyroidism directly affects reproductive function.  However, it is believed that through indirect mechanisms, chronic thyroid dysfunction may affect the brain’s ability to either produce hormones or respond to hormones released by the testicles in feedback loops and may thereby result in reproductive dysfunction and infertility secondarily (in dogs with overt signs of hypothyroidism).

Males that have decreased fertility without any obvious cause may have genetic defects resulting in testicular hypoplasia or degeneration.  Although most of these individuals are sterile, in some cases, one or more litters may have been sired.  Evaluation of the DNA of these individuals through karyotyping (chromosome analysis) may indicate a genetic reason for the infertility.

Testicular aspiration or biopsy can be performed on subfertile or infertile males to help differentiate the cause of the infertility.  Biopsies or aspirates are generally recommended when sperm production is low or steadily decreasing to help elucidate the cause of the problem and help determine if there is a treatment that will improve the dog’s fertility.  Biopsies are taken under general anesthesia through a small incision in the scrotum.  Aspirates can be obtained with heavy sedation.

HOST or hypo-osmotic swelling test evaluates the integrity of the sperm plasma membrane (the membrane that surrounds the entire sperm cell).  The test is performed by placing the sperm in a special solution which results in water being transported across the sperm plasma membrane into the cell to try to equalize the osmotic pressures from the inside to the outside of the sperm.  Water will cross the membrane and enter the cell if the membrane is intact and the transport mechanisms are functioning normally.  If the membrane is not intact, then the transport mechanism will not function properly and no fluid will enter the cell to equalize the pressure differences.  If fluid crosses the membrane, the cell will swell, which results in a bending/curling of the sperm tail.

Sperm chromatin structure assay is a method to assess the DNA content of the sperm head.  This assay compares the amount of DNA present in each sperm and how much variation there is between individual sperm cells.  Normal dogs have very little variation in the amount of DNA present in each sperm head, while dogs with abnormal sperm may have a wide variation in the DNA content of the sperm.

Electron microscopy is a special microscopic technique that allows for very detailed examination of the entire sperm at very high magnifications.  Cross sections and full length sections of individual sperm may be examined to see if there are abnormalities of structure that are beyond that seen by the light microscope.  There are 2 types of electron microscopy, transmission and scanning.  Transmission EM provides a two dimensional view of the interior of the sperm cell, while scanning EM provides a three dimensional view of the exterior surface of the sperm.  Transmission EM is typically more helpful in the assessment of infertility.

Acrosome function is required in order for the sperm to penetrate the egg during fertilization.  In some dogs, adequate sperm may reach the oviduct and surround the egg, but the acrosome reaction may not occur normally resulting in failure of fertilization.  In these dogs, all other sperm testing may be normal.  To assess acrosome function, a drug called calcium ionophore is added to the semen.  This substance will induce the acrosome reaction in normal sperm.  A fluorescent dye is then added and those sperm whose acrosomes react will take up the dye, while those that don’t react, don’t take up any stain.  This test is still being refined for use in the dog, but holds good promise for future use.

Males should be evaluated for reproductive function prior to their first attempt at breeding, if it has been several months or years between breedings, or if fertility begins to decline or is questionable.  In some cases, a routine reproductive examination will suffice, but in others, advanced diagnostics may be required.


Dr. Lopate is board certified in reproduction (Theriogenology).  She owns and operates a reproductive specialty practice providing service to companion animals and horses south of Portland, OR.  Questions regarding male fertility or other reproductive issues may be directed to Dr. Lopate at (503)537-1123, via email at or on the web at



Courtesy of Dr Cheryl Lopate of  REPRODUCTIVE REVOLUTIONS

Cryptorchidism in the Dog

 Cryptorchidism in the Dog

How it happens, How to diagnose, Whether to Treat

In order to understand how cryptorchidism develops, one must have a clear understanding of sexual differentiation and development.  Normal sexual development in the dog is dependent upon 3 factors: 1) the sex chromosomes; 2) normal development of the ovaries or testicles; 3) normal development of the external genitalia (vulva, prepuce) and the effects of the sex steroid hormones on physical appearance (i.e. large jowls and increased size and muscling in males and finer facial features and smaller stature in females).  There is a sex-determining gene, called SRY, which is present only on the Y chromosome.  In its presence, testicles will develop and the fetus will be male, while in its absence, ovaries will develop and the fetus will be female.  Since spermatozoa carry either one X (female) or one Y (male) chromosome, the sex of the embryo is determined at the time of fertilization by the spermatozoa that fertilizes each egg.  All eggs carry one X chromosome.  The sex of the embryo is not distinguishable until after day 30 of gestation when the ovaries and testes can first be differentiated from each other.

Initially, sex cords develop in the area of the kidneys and will eventually differentiate into either ovaries or testes. Furthermore, there are 2 sets of tubules that develop in each embryo initially.  If the fetus develops into a male, the tubules that persist are the mesonephric or Wolffian ducts; and if the fetus develops into a female, the tubules that persist are the paramesonephric or Müllerian ducts. The ductular system that does not develop eventually regresses.  Until sexual differentiation begins each embryo is uncommitted sexually and has sexual bipotentiality.

The substance that determines the progression toward either male or female development is called testis determining factor (TDF) and is controlled only by the Y chromosome.  Testicular differentiation occurs by 36 days of gestation.  The first hormone produced by the embryonic testis is Müllerian inhibiting substance (MIS) (or antiMüllerian hormone or Müllerian regression factor) and is produced by the cells that line the testicular tubules.  In a male fetus, MIS causes regression of the female tubular system between days 36 and 46 of gestation.  The second hormone produced by the embryonic testis is testosterone (T).  Testosterone is converted to an active metabolite (di-hydro testosterone or DHT) which then promotes development of the remaining male tubular tract, the prostate gland, penis, and the external genitalia.

Normal testicular descent in the dog occurs in three steps: 1) movement through the abdominal cavity into the internal inguinal ring; 2) movement through and out of the inguinal canal; and 3) movement from the inguinal canal to the scrotum.  Descent may fail at any point in any one of these 3 stages.  Initially the testes lie near the kidneys in the abdominal cavity. There is a ligamentous cord called the gubernaculum which attaches to the end of the testis and then runs through the inguinal canal and attaches at the far end to the scrotum.  The gubernaculum enlarges under stimulation of certain protein hormones to anchor the testis in place during testicular descent.  Testosterone stimulates development of the genitofemoral nerve which is required for normal testicular descent to begin.  An outpouching of the abdominal lining (the peritoneum) called the vaginal process, grows into the gubernaculum in dogs at about 36 days of gestation.  The gubernaculum continues to grow both in length and width which causes expansion of the inguinal canal and pulls the testis and epididymis toward the scrotum as it grows. Once the testicle has moved through the inguinal canal, the gubernaculum begins to shrink, thereby pulling the testicles into their final scrotal position.  Testosterone is particularly important in the descent of the testes from the external inguinal ring to the scrotum.  The testes pass through the inguinal canal three to four days after birth and reach their final scrotal position by 14 – 35 days of age.

Neither lack nor excess of hormones (testosterone, luteinizing hormone, follicle stimulating hormone or estrogen) are likely to contribute to cryptorchidism.  This is proven by the fact that cryptorchid animals do not have different levels of these hormones compared to normal males, and that treatment with stimulating medications (GnRH, gonadotropin releasing hormone or hCG, human chorionic gonadotropin) does not successfully resolve the condition regardless of the age administered.

Cryptorchidism is considered to be hereditary and an autosomal recessive trait. This means it is carried by both dam and sire lines. It is difficult to determine if a bitch is a carrier of the cryptorchid gene due to the high numbers of male puppies required to all have 2 scrotal testes by 6 months of age (at least 40 normal male puppies).

There are a number of breeds at risk for cryptorchidism including the Boxer, English Bulldog, Cairn terrier, Chihuahua, Miniature Dachshund, Maltese, Pekingese, Pomeranian, Toy, Miniature and Standard Poodle, Miniature Schnauzer, Old English Sheepdog, Shetland Sheepdog, Siberian Husky, and Yorkshire Terrier.  Other inherited conditions associated with cryptorchidism include inguinal and umbilical hernia, hip dysplasia, patellar luxation, and penile and/or preputial defects.

If the testicle begins to enlarge prior to its entry into the internal inguinal ring or if its descent is slowed, it may be retained abdominally.  If it begins to enlarge after entering the internal ring but before leaving the external ring or if normal testicular descent through the inguinal canal is altered or stopped, the animal may become an inguinal cryptorchid.  The right testicle is retained more commonly than the left due to its more forward starting position in the abdomen.

Retained testicles are smaller than scrotal testes, and the location of retention is positively correlated with size. Abdominally retained testes are smaller than inguinally retained testes, which are in turn smaller than testes outside the external inguinal ring but not yet in the scrotum. The reduction in sperm production (spermatogenesis) in retained testicles also worsens with the degree of retention. Even though spermatogenesis does not progress normally in retained testes, steroidogenesis does, so libido is unaffected by this condition. Thus, while cryptorchid dogs may show interest in and breed bitches, unless they have one descended testicle, they will most likely be sterile or at a minimum, infertile. In cases of inguinal retention, dogs may have lower than normal numbers of spermatozoa/ejaculate and increased abnormal forms. Retained testicles are predisposed to neoplasia (9 – 14x higher than normal) and testicular torsion.

Lack of 2 testicles in the scrotum by 8 weeks of age is considered to be suspicious for cryptorchidism. Classically, it has been accepted by the time an animal reaches 6 months of age, if it does not have 2 scrotal testicles, it is considered a cryptorchid. But realistically, with the vast differences in age at puberty between breeds this is probably not a reasonable expectation.  Based on the average age at puberty for any given breed, one would expect to have both testes in the scrotum within 2 months of attaining puberty to be considered normal. This means that for large and giant breed dogs, testicular descent may not be complete until well over a year of age.  Small and medium breed dogs should still be considered cryptorchid if 2 testes are not in the scrotum by 6 – 8 months of age.

When trying to determine the location of a retained testicle, careful palpation of the inguinal region and the area just lateral to the penis and prepuce should be performed.  Lymph nodes and fat are commonly mistaken for testes, as is the gubernacular outgrowth within the scrotum.  Testicles should be freely movable and have an attached epididymis.  Ultrasonography may be attempted to locate a cryptorchid testicle and is more successful in locating inguinal rather than abdominal testes. This is due to the smaller size of the abdominal testes and the fact that they may be located anywhere in the abdominal cavity (although they tend to lie along a line drawn from the end of the kidney to the opening of the external inguinal ring).  Abdominal testes appear to have the same structure as scrotal testes on ultrasound examination.  However, if an abdominal testis is neoplastic, it may be larger and have an abnormal appearance.

In cases where there is no history of neutering but there are no testicles palpable, an hCG or GnRH stimulation test can be performed to determine if testicular tissue is still present. A baseline testosterone is obtained. A stimulating hormone is administered and testosterone concentrations are obtained at 1 and 4 hours post injection.  The baseline concentration should more than double if testicular tissue is present.  Cryptorchid males do tend to have less marked response to GnRH stimulation testing than their intact counterparts.  Use of serum LH testing is not accurate for diagnosis of castrated males due to overlap of resting ranges of cryptorchid and neutered males.

Typically, no treatment is recommended for cryptorchidism beyond castration.  If an animal does not have 2 scrotal testes by the time 2 months beyond puberty, the individual should be neutered and not used in any breeding program due to the hereditary nature of the disease and the other associated heritable conditions. There are a number of published and anecdotal protocols involving multiple injections of either hCG or GnRH to stimulate precocious puberty and encourage testicular growth and descent, but there is no strong scientific evidence that any of them is consistently effective.  Various degrees of success are associated with these treatments proving the multifactorial and polygenetic nature of the disease.

Further anectodal reports of massaging the inguinally retained testes towards the scrotum to hasten it’s descent are unlikely to be the case except in the shy individual who is retracting the testes towards the body when touched. Daily manipulation of the scrotum and perineal area, may make these individuals more relaxed when the scrotum is palpated, thus allowing the testes to remain in their scrotal position.

In humans, where the basis for medical treatment was derived, treatment is actually both medical and surgical.  Because of the increased risk of testicular cancer in cryptorchid men at middle age, doctors treat cryptorchids aggressively.  Young boys (pre-pubertal) who are found to be cryptorchids first have surgery to locate the testicle and then the testicle is sutured to the scrotum with a heavy suture. The goal of the suture is to put tension on the testicle to pull it towards the scrotum as the gubernaculum should have. Once the testicle is in the scrotum, the suture material hopefully creates scar tissue causing the testicle to adhere there.  After surgery the boys are treated with stimulating hormones to induce precocious puberty and thus stimulate testicular and gubernacular enlargement. Therapeutically, the combination of hormone therapy and surgery result in testicular descent in about ⅔ of the patients who have inguinal or lower cryptorchidism.  Success with abdominal cryptorchids is very low.  Of those that descend a large proportion (about 30 – 50%) will relapse once the suture breaks down and hormone therapy has been stopped.

In humans, doctors are not concerned about male fertility when considering medical and surgical therapy for cryptorchidism. There are so many advanced techniques available for subfertile men nowadays, that this problem can be overcome using in vitro fertilization(IVF), intracytoplasmic sperm injection (ICSI) or other advanced reproductive techniques. Nor are doctors concerned about a patient passing on this potentially heritable condition to their male offspring. Because most families have only 1 – 3 children, the chance of a male offspring having the condition is low.  Human doctors are mainly concerned about decreasing the risk of testicular neoplasia in middle age.  So while in animals reducing the risk of neoplasia is also a concern, we are also very concerned with passing heritable defects through lines and the ability of the male to be fertile without expensive reproductive interventions.  Since most dogs only live to be between 10 and 14 years of age, the numbers of testicular tumors found in intact males who are cryptorchid is much lower than the incidence in humans because the human lifespan is so much longer.

Furthermore, successful medical treatment of cryptorchids may increase the fertility in an affected dog, thereby perpetuating the trait in his offspring.  Additionally, the increased risk of neoplasia remains whether the testes descend or not, so in a successfully treated animal, failure to neuter at a young age increases his risk for neoplasia later in life.  Since cryptorchidism is associated with other heritable defects, (hip dysplasia, patellar luxation, inguinal hernia etc.) which can affect quality of life for our pets, breeding these individuals is strongly discouraged.

Removal of all affected males, their offspring and their parents from the breeding program is the recommended course. Waiting until puberty is fully attained is recommended before deeming any individual a cryptorchid.

Canine Mycoplasma and its Role in Reproductive Disease

Mycoplasma infections have been implicated as a cause of infertility in both bitches and stud dogs. As a result, mycoplasma continues to receive attention as a potential concern for purebred dog breeders. This article discusses what is currently known about canine mycoplasma infections and outlines a management approach for breeding animals.

What is mycoplasma?

Mycoplasmas are bacterial organisms that, because of their extremely small size, have been placed in a separate class. Also, unlike any other bacteria, mycoplasmas lack a rigid cell wall which makes them unaffected by antibiotics that act by invoking cell wall damage (for example, penicillin). Mycoplasmas are extremely fastidious organisms that are difficult to culture without special media, and even then may be difficult to recover. Ureaplasmas are a distinct type of mycoplasmas that have been sub classed and are identified by their own name.

Mycoplasma as part of the normal flora:

Several mycoplasma species have been found to be normal inhabitants of the upper respiratory and genital tracts of dogs and cats, and as a result they can be routinely isolated from oral, nasal, conjunctival and genital mucous membranes. Several studies have specifically looked at the frequency of mycoplasma recovery from the genital tracts of fertile versus infertile bitches and stud dogs, and no significant difference has been found. Therefore, recovery of mycoplasma from a vaginal or semen culture does not always correlate to reproductive disease, and likewise does not always need to be treated. Since these organisms exist in the respiratory tract as well as the reproductive tract, aerosol transmission from dog to dog (airborne, licking, sniffing, etc.) is probably more frequent than venereal transmission.

When to worry about mycoplasma?

While mycoplasmas may be normal inhabitants of the reproductive tract, they have been associated with infertility, lesions of the reproductive tract and sperm abnormalities. As with many opportunistic pathogens (organisms that may cause disease but frequently don’t), clinical disease often results when an animal is under stress and/or exposed to high numbers of organisms. Close, intensive breeding conditions (as in a large kennel or at indoor dog shows) provide the opportunity for high numbers of organisms to develop. A healthy dog or bitch especially if housed individually, however, may not become diseased even after known exposure to the organism.

It has been found that the administration of broad spectrum antibiotics may suppress many other bacteria that make up normal flora and allow mycoplasmas to overgrow. Therefore, the prophylactic use of antibiotics pre breeding is not recommended as it may actually create a pathogenic state, and may contribute to the development of antibiotic-resistant populations of organisms.

A mycoplasma culture should be performed if:

  1. A dog has missed several bitches (no conception)
  2. A semen evaluation shows morphologically abnormal sperm cells.
  3. A bitch has not conceived having been bred to a fertile stud dog on appropriate days.
  4. A dog of bitch produces conception but has a documented high rate of fetal resorption.

It is important to remember that there are many other causes of the above problems, and so a mycoplasma culture should be only one part of a thorough diagnostic investigation performed by a veterinarian experienced in canine reproduction.

Proper Mycoplasma Culture Technique:

Due to their fastidious nature, mycoplasmas require special techniques for successful growth in cultures. As a result, mycoplasma cultures should only be sent to laboratories competent in the recovery of the organism. It is recommended that ureaplasma is cultured for at the same time, since it is a similar organism and has also been implicated in infections of the reproductive tract.

Proper technique in obtaining the sample to be cultured is also extremely important. In bitches, it is recommended that the vaginal area close to the cervix be sampled using a guarded swab. In stud dogs, it is important that a semen specimen be collected using sterile technique, avoiding urethral contaminants.

What to do about normal fertile dogs and bitches?

Since mycoplasma is frequently cultured from the vagina of normal fertile bitches, routine pre breeding cultures of bitches are not warranted. Since mycoplasma is frequently recovered from culture of the prepuce and/or semen of normal fertile males, routine pre-breeding cultures may show some growth of mycoplasma as part of the normal flora. However, some owners may choose to periodically have a dog’s semen culture for mycoplasma. While a negative result is definitive, the significance of a positive result must always be determined by correlation to semen evaluation and clinical condition. Unfortunately, a dog’s fertility status cannot be determined on the basis of mycoplasma recovery.


            Mycoplasma infection is only one of many factors that may impact canine fertility. Working with an experienced veterinarian with a thorough, systematic approach to investigating fertility problems will pay dividends to your breeding program.

Approach to Infertility in the Bitch and in the Dog


  1. Fontbonne, DVM, MSc, DECAR

Ass. Pr., Animal Reproduction–Alfort National Veterinary College (Paris)

Cedex, France

In comparison to the last 10 or 20 years, veterinarians are now frequently requested to solve fertility problems in the dog, mainly due to the increased popularity of purebred dogs as well as for sentimental or financial reasons. In fact, breeders may be concerned about different kinds of problems which include but are not limited to true infertility (their bitches produce no pups after mating or Artificial Insemination), anoestrus or a low prolificacy rate.

Many different problems can lead to infertility including hormonal problems, infectious diseases, congenital or acquired defects of the genital tract. We recommend that veterinarians follow a very strict progression, commencing with the most frequent cause to the most uncommon cause. In the bitch, things become even more difficult when we realize that apparent infertility can be due to very different situations which prove difficult to distinguish, such as lack of fertilization (no union between eggs and sperm) and early embryonic death.

  1. 1. In the Bitch

1.1 Mistimed Breeding or Artificial Insemination

According to the vast majority of scientific publications, mistimed breeding represents by far the most common cause of infertility in the bitch. This is why a veterinarian willing to solve fertility problems in the bitch has first to be skilled in timing ovulation in the bitch.

Apart from progesterone assays, ovarian ultrasonography is especially indicated in infertile bitches, as it represents the most accurate way to determine the precise date of ovulation.

1.2 Infertility with Prolonged Interoestrous Intervals

The apparent prolongation of interestrous intervals occurs in dogs with a silent heat, defined as ovarian activity in the absence of overt physical and behavioral changes characteristic of canine estrus.

Among the hormonal causes of anoestrus we find hypothyroidism, hyperadrenocorticism, hyperprolactinemia, or bitches treated with hormonal compounds such as progestagens, androgens (racing dogs) or anabolic steroid compounds. Ovarian cysts that secrete progesterone may cause prolonged interestrous intervals.

Bitches housed in very bad environmental conditions (including a high concentration of animals, low luminosity, low quality food) may undergo prolonged interestrous intervals.

1.3 Infertility with Shortened Interoestrous Intervals

This type of infertility may be divided into two major causes: bitches suffering from ovarian hyperstimulation (mainly follicular cysts or Granulosa cells tumor), and/or bitches showing a premature decline in progesterone during diestrus.

1.3.1 Ovarian Cysts or Tumors

It is important to diagnose and remove these hormonally active cysts or tumors as quickly as possible for at least two reasons. First, it is necessary to cure them and try to restore fertility. Second , the secretion of high quantity of estrogens may act on the uterus as a potential factor towards the cystic endometrial hyperplasia–pyometra complex, but also on the bone marrow in creating progressive non regenerative anemia.

Follicular cysts may be single or multiple; if multiple cysts are present in one ovary, the cysts do not communicate. The ovarian cysts in the bitch may be present in only one or both ovaries. When possible, it is much more valuable to perform ovarian ultrasonography.

Some authors recommend induction of luteinization of the cystic follicles, using GnRH or hCG. We personally do not recommend such protocols, as they increase the progesterone plasma level after a prolonged period of estrogen secretion. Based upon our clinical experience, this treatment very often leads to the occurrence of pyometra in the following weeks. Surgical removal of a cyst, or aspiration of a cyst with a fine sterile needle under laparotomy or ultrasonography may be new alternatives in therapy.

Granulosa cells produce estrogens; and therefore, it is not surprising that GCTumours often lead to infertility with prolonged heat periods.

1.3.2 Premature Decline in Progesterone

Split heats are defined as successive short proestrus signs, at intervals of 2 weeks to 2 months, associated with short interestrous intervals. This pattern is more often observed in young bitches and leads to no real infertility in the rest of the genital life of the bitch.

Anovulatory cycles are not frequent in bitches. In such anovulatory cycles, serum progesterone level never increases above 3.5 to 6 ng/ml. This explains why the following heat period will often occur earlier than usual.

Bitches may also suffer from hypoluteoidism, which is the lack of progesterone secretion during pregnancy which makes the pregnancy impossible to maintain. Some breeds are well known to express hypoluteoidism, like Rottweilers and German Shepherds. Progesterone supply can be given parentally (progesterone in oil: 2 mg/kg every 3 days; ally-trenbolone … ).

In France, veterinarians often use oral micronised progesterone which is currently given to women.

1.4 Infertility with Normal or Sub-normal Interoestrous Intervals

1.4.1 Hormonal Problems

Hormonal defects may be suspected also in bitches with regular interestrous intervals, and veterinarians should control the hormonal status of the bitch during the heat period and also during pregnancy.

1.4.2 Infectious Diseases

Several viruses have been shown to playa potential role in canine infertility.

Several elements suggest that Canine Herpes Virus (CHV) may well act on infertility in the bitch. Recently, some papers have pointed out the potential incidence of a parvovirus Minute Virus of Canines (CPV1) on resorption during the first half of pregnancy.

The incidence of bacterial infections on canine infertility is better documented. Canine Brucellosis could generate early embryonic or fetal death through endometritis.

Other specific bacterial diseases have been suspected to act on canine infertility.  However, usual genital bacteria may playa real role on infertility. Canine Mycoplasmas and Ureaplasmas are commonly isolated in the genital tract of fertile and infertile bitches. But it has been shown that there is a higher incidence of these agents in the vagina of infertile bitches.

Many bacteria are commonly isolated from the uterus and the vagina of normal fertile bitches. Several studies barely demonstrate any difference in the composition of the vaginal flora between fertile and infertile bitches. But it has been shown that in case of vaginitis, there are significant qualitative and quantitative variations. Strong evidence exists that bacteria causing vaginitis may lead to infertility. It may well have been underestimated due to lack of specific clinical signs and due to the difficulty of the clinical examination of the vagina of the bitch.

1.4.3 Drug-Induced Infertility

In practice, many breeding bitches may be treated with drugs that may contribute to the decline of fertility. Steroid hormones and anti-fungal compounds may create hormonal defects in pre-puberal or adult bitches. Abortive drugs such as prostaglandins, antiprogestins and antiprolactinic substances have to be avoided during pregnancy.

1.4.4 Anatomical Abnormalities of the Genital Tract

Some bitches do not manage to mate because of congenital or acquired abnormalities of the posterior genital tract (vulva, vestibule or vagina).

Acquired diseases or abnormalities of the posterior genital tact (scars after a bad

parturition, episiotomy, violent mating … ) may also lead to the lack of copulation.

1.4.5 Uterine Pathology

Endometritis is a common cause of infertility in mares. In bitches, however, it is hard to diagnose. Endometrial cytology, eventually performed after endoscopic cannulation of the cervix, may be valuable.

Bitches with cystic endometrial hyperplasia (CEH) are often infertile due to implantation failure after conception. Somehow, ultrasonography usually permits the visualization of the glandular endometrium.

1.4.6 Abnormal Sexual Behaviour

Many psychological factors may influence sexual receptivity in bitches. Some authors think that psychology may influence factors like ovulation or early embryonic death in the bitch.

1.4.7 Miscellaneous Causes

Bitches with systemic diseases like diabetes mellitus, hyperadrenocorticism or renal insufficiency may likely be infertile.

Finally, breeders stress nutrition when their breeding kennel suffers from decreased reproductive results. Little is known in this regard.

  1. 2. Male Infertility

After mistimed breeding, male infertility may well be the most common cause of conception failure in bitches presented with infertility.

Very little is known about male infertility in the dog. Regarding human male infertility, the cause remains unknown in 70% to 74 % of cases. In the area of human medicine, when the semen is of poor quality, most of the time assisted reproduction techniques are utilized such as in vitro Fertilization (IVF) or Intra-Cytoplasmic Sperm Injection (ICSI). These techniques are not routinely available to the dog; therefore, the prognosis of infertility often remains very poor. However, some infertility causes can be partially or totally cured if the veterinarian is consulted early enough. But in only 10% of dogs presented with infertility may fertility be restored after diagnosis and appropriate treatment.

Veterinarians willing to diagnose and attempt to cure male infertility must be completely knowledgeable about the investigation of the male reproductive function and especially the method of performing the sperm collection and analysis (spermiogram).

2.1 Prostatic Problems

A prostatic problem often plays a direct role in decreasing fertility. The prostate is the only accessory gland present in the dog , as no seminal vesicles exist. Chronic prostatitis has been shown to be a rather common cause of infertility in dog. It is often suspected when a dog brought for semen collection for Artificial Insemination or freezing of the semen suffers from hematospermia, especially in the 3rd fraction of the ejaculate.

In case of hematospermia, when suspecting an infectious prostatitis, Levy et al.(2006) showed that bacterial examination after an ultrasound-guided biopsy seems the only reliable diagnosis technique, much more than semen culture.

When treating prostatic problems in the dog, the use of common anti-androgenic compounds may definitively alter the quality of semen and subsequent fertility. That is why many reports have been made about the use of 5 a reductase inhibitors (finasteride). Finasteride is a 4-azasteroid synthetic drug that inhibits 5a-dihydroreductase, an enzyme that is responsible for the metabolism of testosterone to dihydrotestosterone in the prostate, liver and skin.

Recently, some new anti-androgenic drugs (osaterone acetate) seemed to decrease the size of the canine prostate without altering spermatogenesis and may be potentially used in breeding dogs (Mimouni et al. 2006).

2.2 Infectious Diseases

Infectious diseases probably represent a major cause of infertility in male dogs living in breeding kennels. Germs can cause prostatitis, which may alter the biochemical composition of prostatic fluids and may induce a permanent or temporary blockage of the ducts as they enter the prostate. But infections often lead to an orchitis/epididymitis, with a subsequent alteration of the quality of the semen. Canine Brucellosis infection in males have been well described and any male dog suffering from infertility with a bad spermiogram should be serologically tested for this disease. Recently also, the interest of leukocytes quantification in the ejaculate has been further studied (Martin 2005).

2.3 Hormonal Dysfunctions

Central hormonal causes are not well documented. Testicular tumors which are responsible for excessive hormonal secretion (Sertoli cells tumors, Leydig cells tumors) may cause a decrease of spermatogenesis, even when these tumors are located only in one testicle and still quite small in size. Hypothyroidism is often stated as a potential cause of infertility. The link between hypothyroidism and low quality semen is still unclear and probably very much overestimated .

2.4 Retrograde Ejaculation

Retrograde ejaculation consists of a retrograde backflow of semen into the bladder when ejaculation occurs. This leads to either aspermia or oligospermia. In dogs, retrograde ejaculation is not well documented. This problem does not seem to be permanent. Treatment of retrograde ejaculation has been better documented recently (Romagnoli 2004, Beaufayset a/2004). Treatment may be attempted by collecting semen when the bladder is full (which makes the sphincter close more firmly). Sympathomimetic drugs like phenylpropanolamine (3 to 4 mg/kg per os twice daily) or pseudoephedrine (4 to 5 mg/kg per os three times daily or 1 to 3 hours before semen collection or attempted breeding) may be tried.


Alain Fontbonne, DVM, MSc,


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