Infertility: male – overview

• Fertility in the male dog is dependent on normal behavior and libido, physical ability, and adequate semen quality.
• Infertilty can result from poor breeding behavior, poor libido, musculoskeletal problems preventing breeding or poor semen quality.
• Apparent infertility can stem from problems with kennel husbandry or problems with the female mate.
• Evaluation and therapy for infertility in the male dog is therefore multifactorial.
• True infertility due to poor semen quality has a poor prognosis for resolution, but usually does not impact the dogs general health.

• Acute or chronic failure to impregnate bitches.

• Request for evaluation of fertility after failure to impregnate bitches following breedings perceived to be adequately managed.

• Senescence can be associated with declining semen quality as well as with inability to breed naturally for musculoskeletal reasons.
• Senescent subfertility or infertility varies with individuals; large breed dogs may become subfertile at a younger age than small breeds. Most dogs' fertility start to decline at different individual rates after middle age (just like humans).
• The American Kennel Club requires veterinary confirmation of normal semen quality for registration of breedings involving males over the age of 12 years (not applicable in the UK).

• Physical inability to naturally breed occurs in some breeds (eg English Bulldog Bulldog ).
• Infertility subsequent to immune mediated orchitis Orchitis / epididymitis may have breed tendencies and be associated with small gene pools (more inbred individuals).
• Semen morphologic abnormalities Semen: evaluation can be associated with the degree of inbreeding.

• Brucella canis Brucella canis (not applicable in UK).

• The investment in a dog fertility evaluation Breeding soundness examination can be substantial.
• Semen evaluation Semen: evaluation cost around £80 with immediate results. In the UK, biopsies etc tend not to be carried out - around 90% can be diagnosed by a microscopic examination of the sperm quality.

• The risk of inducing immune mediated orchitis from a diagnostic testicular biopsy is minimal.

• Poor libido Deficient libido in male.
• Physical inability to breed a female naturally (ie achieve a copulatory lock or tie).
• Poor semen quality.
• Normal semen evaluation with poor sperm function.

• Passive or insecure male.
• Environment at collection not conducive to normal libido (eg veterinary clinic).
• Nonreceptive female due to behavioral problems (dominant) or not in estrus (not in the receptive/fertile period of the estrous cycle).
• Mismatch of stud dog and brood bitch height or conformation (eg English Bulldog).
• Vaginal anatomic problems in the bitch (stricture).
• Phimosis.
• Bilateral cryptorchidism Testicle: cryptorchidism.
• Abnormal motility (asthenospermia), morphology (teratospermia) or sperm count (oligospermia or azoospermia).
• Lack of semen (aspermia).
• Pyospermia.
• Iatrogenic causes.
• Neoplasia (testes Testicle: neoplasia , prostate Prostate: neoplasia , urinary tract).
• Significant systemic disease.

Specific

• Normal male breeding behavior can be inhibited by prior negative experience (correction by owners, aggressive bitch) or simply inexperience.
• Semen collection Semen collection for artificial insemination Artificial insemination: non-surgical Artificial insemination: surgical requires an environment in which the dog is relaxed and not concerned about previous negative experiences (vaccination, anesthesia, etc).
• Nonreceptive female dogs can be markedly aggressive with male dogs and inhibit even later attempts at copulation when they are receptive Failure to accept male at breeding.
• Dogs and bitches need to be similarly sized and anatomically compatible for natural breedings to take place.
• Bitches with circumferential vaginal strictures usually cannot be bred naturally with a copulatory lock (tie).
• Slow sperm motility, abnormal sperm morphology, and/or low sperm counts can render dogs subfertile or infertile.
• Lack of semen may indicate a disorder of sexual differentiation Disorders of sexual development.
• Inflammatory disease of the urogenital system (cystitis Cystitis , urethritis, prostatitis Acute prostatitis , orchitis) can affect semen quality adversely.
• Brucella canis Brucella canis is the single significant venereal disease that should be screened for in every breeding dog, and ruled out in any acquired infertility case.
• Administration of drugs (cimetidine Cimetidine , ketoconazole Ketoconazole , finasteride) that impact testosterone production or metabolism, or which impact rapidly dividing cells (chemotherapeutic or immunosuppressive drugs) can affect semen quality adversely.
• Sertoli cell tumors Testicle: sertoli cell tumor , interstitial cell tumors Testicle: neoplasia , and seminomas of the testes Testicle: seminoma.
• Transitional cell tumors of the bladder, urethra and/or prostate are most common neoplasia of the urogenital tract; adenocarcinomas of same are the second most common. Transmissible venereal neoplasia is uncommon in developed countries but should be considered because of travel.
• Renal insufficiency, hepatic disease, endocrinopathies, and systemic inflammatory/infectious disease can impact fertility acutely or chronically.
• Sperm functional disorders (capacitation, membrane integrity, acrosome reaction).
• Rarely, microtubule defects render sperm cells nonmotile.

• (Orchitis and epididymitis Orchitis / epididymitis result fromBrucella canisinfection.)
• Infectious prostatitis Acute prostatitis , often accompanied by cystitis and urethritis and negatively impact semen quality.
• Systemic fever can reduce spermatogenesis.
• Hard training with prolonged periods of hyperthermia can reduce spermatogenesis.
• Focal scrotal and/or epididymal inflammation can reduce spermatogenesis.

• The spermatogenic cycle requires approximately 62 days. Recovery of the semen quality may require 90-365 days.
• Daily ejaculation for approximately a week will deplete sperm reserves, but a normal dog should remain fertile from his daily sperm production.

• Not applicable unlessBrucella canisin a kennel population or transmissible venereal tumor in free ranging dogs.

• Husbandry problems.
• Infertile bitch.
• Behavioral problems.
• Physical incapacities.
• Systemic disease.
• Specific reproductive tract disorders.
• Semen abnormalities.
• Infectious venereal disease.

• May be no significant history other than failure to reproduce, chronically or recently.
• Question diet, medications, environment, supplements, and exercise.
• Question breeding management.
• Question breeding history, family history.
• Travel?
• Performance enhancing drugs (show or trial dogs in particular)?

• May be none other than failure to reproduce.
• Any signs of systemic disease?
• Urination changes?
• Any discharge from prepuce or penis?
• Stool character?
• Any change noted in testicular size or symmetry?
• Orthopedic pain?

• History including reproductive history.
• Investigate breeding husbandry.
• PE.
• Reproductive organs:
  • Bilaterally descended testes?
  • Any inguinal herniation?
  • Scrotal dermatitis?
  • Testicular size, shape, symmetry?
  • Hydrocele? Spermatocele? Mucocele?
  • Abnormal prostatic shape, symmetry, pain?
  • Prominent epididymi?
  • Penis evaluation?
  • Evaluate erection and ejaculation.
• Semen evaluation Semen: evaluation.
• Ultrasonographic evaluation of urogenital tract Ultrasonography: testes.
• Clinical pathologic evaluation: CBC, chemistry panel, appropriate endocrine tests, urinalysis with culture.
• Possibly LH and post GnRH testosterone level testing.

Semen evaluation Semen: evaluation

• A complete semen evaluation is essential in investigating infertility. If a semen analysis is not performed it is impossible to rule out the male as a source of infertility. Semen must be evaluated as soon as possible after collection, because changes in temperature, exposure to light, and exposure to any type of chemical (lubricants, etc) can change sperm motility and adversely affect fertility. Motility is the most influenced parameter in the semen analysis. Gross motility is examined first. Mix the semen sample as motile sperm cells will try to swim upward and dead cells will settle to the bottom. For motility evaluation, place a drop of semen on a warm slide. Check individual motility of the cells. If the sample is too concentrated, dilute the sample by placing a drop of saline or Na citrate on a warm slide before placing a semen drop on the slide. Examine the sample under high dry (40X) power. A concentration of approximately 10 cells/high power field is optimal to accurately estimate the number of cells that are progressively moving across the field. Examination of the sample should occur quickly as the motility changes very rapidly with heat, light, and cold.
• Morphology is usually examined with an eosin-nigrosin (Society for Theriogenology) or diff quick stain to highlight the cells. Examine the cells under 100X (oil) to fully assess morphology. Count 100-200 cells, differentiating normal from abnormal cells. In order to do a full spermiogram, differentiate the abnormalities by type. Abnormalities are classified as primary and secondary. Primary abnormalities are thought to arise in the testes; secondary abnormalities arise in the epididymi or ejaculate. Secondary abnormalities may be just as serious as primary. Primary abnormalities decrease through sperm transit and secondary abnormalities increase through transit. Evaluate the presence of inflammatory cells in the sample as well. Some white blood cells are anticipated from normal preputial smegma.
• A sperm count is another essential element in a semen evaluation. To count the concentration of semen sample a hemocytometer can be used. The hemocytometer is loaded with a 1:100 dilution of semen. A hemocytometer cover slip is placed over the chambers, the chambers are filled, and the sample allowed to settle. All the sperm heads in the middle big square (the square with 25 smaller squares and another 16 squares within each of these 25, within the triple lines) are counted. The number of sperm heads counted in a single chamber is multiplied by 106 to give the concentration of cells/cc. Both chambers of the hemocytometer should be counted and the numbers should not differ by more that 10%. The hemocytometer grid has 9 large squares. The central square has triple lines around it. Inside the triple lines are 25 smaller squares (also bounded by triple lines). Within each of the 25 squares are 16 squares. A hand dilution is made by diluting 1 part semen with 9 parts formal-buffered saline to make a 1:10 dilution, then taking 1 part of the 1:10 dilution and adding 9 parts of formal-buffered saline to make a 1:100 dilution. This is a little more time consuming, but the cells tend not to clump, so you get a more accurate sperm count.
• Alternatively, an automated sperm counting machine calibrated and validated for use in the dog provides an accurate sperm count per ml as well (Spermcue).
• Total sperm numbers are calculated by multiplying the concentration X the volume to give the total number of cells in the ejaculate. Take that number and multiply by the percent progressively motile cells to get the total number of progressively motile cells. Multiplying this number by the percent normal morphology cells will give the total number of normal, motile cells (functional sperm count).
• Normal sperm count is >200,000.000 with >70% normal progressive motility and >80% normal morphology. Sperm function (membrane integrity) is difficult to evaluate without special stains or phase contrast microscopy.

• Histopathology of a testicular biopsy confirms the diagnosis of immune mediated orchitis if performed early enough in the course of the disease, permitting prognostication but therapy is ineffective.
• Histopathology of the testes is important for retrospective evaluation if an infertile dog is neutered.

• Infertilty resulting from husbandry or female problems.
• I 131 induced hypothyroidism in beagles did not impact fertility (semen quality or libido).
• Normal flora (gram positive, gram negative, mycoplasma species) of the prepuce and distal urethra should not be implicated in cases of infertility without accurate documentation (prostatic culture, quantitative semen and urethral cultures, culture of testicular biopsy).

• Correct problems with husbandry; ovulation timing in bitches, breeding management, natural breeding behavior reinforcement, proper insemination technique if not natural breedings.
• Optimize stud dog health (pre breeding evaluation, excellent nutrition, preventative medicine for heartworm (not in UK), parasite prevention, adequate but not excessive vaccination).
• Select dogs from fertile lines for use as studs.

• IfBrucella canisconfirmed (AGID) remove dog from breeding kennel (not applicable in UK).
• If urogenital inflammatory or infectious disease is diagnosed (urinary tract infection, septic prostatits) treat effectively and re-evaluate after adequate time has elapsed for sperm production.
• If unilateral testicular neoplasia with associated endocrinopathy is detected (Sertoli cell tumor) unilateral orchiectomy Castration may be curative if minimal contralateral atrophy is evident.

• Repeat semen evaluations.

Treatment

• Periodic semen evaluations; appropriate testing (eg recheck urine cultures).
• Artificial insemination Artificial insemination: non-surgical Artificial insemination: surgical if natural breedings not possible.
  Not permitted by the Kennel Club in the UK.
• Assisted reproductive technology (eg trans cervical insemination).
  Not pemitted by the Kennel Club in the UK. Puppies cannot be registered - not a problem in greyhounds or working sheep dogs.

Monitoring

• Annual physical examination, appropriate screening tests (CBC, chemistries, urinalysis/culture) and semen evaluation advised for stud dogs.
• Ultrasonography of urogenital tract if abnormalities are detected on physical examination, laboratory results or spermiogram.

• Varies with etiology, however overall prognosis for infertile or subfertile dogs is poor.

• Improvement in spermiogram when evaluated serially, over 90 days from resolution of the insult.

• Irreversible damage to spermatogenic apparatus.

Refereed papers

• Recent references from PubMed and VetMedResource.
• Memon M A (2007) Common causes of male dog infertility. Theriogenology 68 (3), 322-328 PubMed.
• Kustritz M V, Johnston S D, Olson P N et al (2005) Relationship between inflammatory cytology of canine seminal fluid and significant aerobic bacterial, anaerobic bacterial and mycoplasma cultures of canine seminal fluid; 95 cases (1987-2000). Theriogenology 64 (6), 1333-1339 PubMed.

Other sources of information

• Johnson C (2006)Current concepts on infertility in the dog.Waltham Focus16(3); 7-12.