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Basics ⬇

Basics

Definition

  • Diminished or absent fertility; does not imply sterility.
  • Results from a wide range of problems that prevent the delivery of sufficient numbers of spermatozoa to fertilize ovulated, mature oocytes in the bitch or excessive numbers of biochemically/structurally compromised spermatozoa.

Pathophysiology

  • Spermatogenesis-encompasses the formation and development of spermatozoa from spermatogonia to mature spermatozoa; a coordinated, hormonally controlled, cyclic process; approximately 70 days required for a complete phase: the testicular phase is 61.9 days; the epididymal phase is 10–14 days. Testicular problems require at least 70 days for recovery; epididymal problems require up to 10–14 days.
  • Azoospermia-no spermatozoa in the ejaculate.
  • Oligozoospermia-low numbers of spermatozoa.
  • Teratospermia-high numbers of abnormally shaped spermatozoa.
  • Asthenospermia-reduced motility.
  • Primary causes-impaired or arrested spermatogenesis; blockage of the excurrent ducts; genitourinary inflammation; testicular neoplasia; environmental stress; congenital abnormality; endocrine abnormality.

Systems Affected

  • Reproductive
  • Endocrine/Metabolic
  • Musculoskeletal
  • Nervous

Genetics

  • The incidence of verifiable heritable causes of infertility in the stud dog is increasing.
  • Cryptorchidism-likely a heritable, sex-limited polygenic autosomal recessive trait in dogs; associated with increased frequency of inguinal/umbilical hernias, patellar luxation, preputial and penile problems.
  • Alpha-L-fucosidase deficiency is a storage disorder causing acrosomal dysgenesis.
  • Primary ciliary dyskinesia (PCD)-congenital abnormality of ciliary ultrastructure; absent, irregular, or asynchronous motility patterns of all ciliated cells; diagnosed by electron microscopy of spermatozoa.
  • Hypothyroidism-effect on male fertility is probably minimal.

Incidence/Prevalence

True incidence unknown; is probably increasing with continued in-breeding. The percentage is probably higher than expected as the full degree of genetic effects has not yet been realized.

Signalment

Species

Dog

Breed Predilections

Relatively higher prevalence of specific problems seen in breeds with a small genetic pool or with intensive in-breeding.

Mean Age and Range

Prevalence increases with age.

Signs

General Comments

General complaint-no puppies produced; whelping rate <75% when bred with correct timing to fertile bitches; owner suspects male dog infertility.

Historical Findings

  • Age of testicular descent
  • Age at first attempted mating
  • Dog's temperament (high-strung)
  • Libido and breeding behavior
  • Frequency and number of matings
  • Method used to time breedings
  • Type of semen used for breeding (fresh, fresh-extended, chilled-extended, or frozen)
  • Ability for the dog's sperm cells to survive chilling or freezing
  • Handling of semen and route of insemination
  • Litter size(s)
  • Familial history of infertility
  • Degree of in-breeding
  • Fertility status of bitches bred
  • Brucella canis status of all breeding animals
  • Current and previous drug and dietary therapies, especially corticosteroids and steroid hormones
  • Previous medical or surgical illnesses

Physical Examination Findings

  • Sheath and penis-palpate to identify masses or adhesions.
  • Non-erect penis-exteriorize to identify clinically important lesions of the superficial mucosa and any damage to the os penis.
  • Testes and epididymides-palpate and examine, note the size and symmetry of the epididymides relative to the testes.
  • Internal urethra and prostate-digital rectal palpation to determine location, size, and symmetry.

Causes

Incorrect timing of breeding-most common cause

Congenital

  • Chromosomal abnormalities: XXY syndrome and XX disorder of sexual development (see Sexual Development Disorders).
  • Germinal cell aplasia-biopsy reveals “Sertoli cell only” syndrome.
  • Segmental aplasia of the epididymis or vas deferens-causes either oligospermia (unilateral) or azoospermia (bilateral).

Acquired

  • Incomplete ejaculation-unfamiliar surroundings; slippery flooring; no estrous bitch; dominant owner or bitch present.
  • Obstruction of the efferent ducts, epididymides, or ductus deferens-leads to azoospermia if bilateral; sperm granuloma, spermatocele, acute inflammation, chronic inflammatory stenosis, segmental aplasia, neoplasia, previous vasectomy, and attempts to tack testes into a scrotal location.
  • Hyperthermia/heat stroke.Inflammation or infection of the testes-especially Escherichia coli; requires prompt and aggressive treatment to prevent infertility.
  • Hypothyroidism-role unclear and extremely rare; evaluate thyroid function with poor semen quality; may be associated with decreased libido.
  • Hyperprolactinemia-role unclear; evaluate prolactin levels with azoospermia.
  • Hyperadrenocorticism-causes testicular atrophy and oligospermia; probably reversible.
  • Drugs-parasiticides, corticosteroids, anabolic steroids, estrogens, androgens, progestagens, GnRH agonists/antagonists, ketoconazole, amphotericin B, some antifungal agents, may interfere with or interrupt spermatogenesis; assess all topical and systemic therapies.
  • Environmental toxins-endocrine-disrupting contaminants can affect the hypothalamic-pituitary-gonadal axis and gonadal steroidogenesis; effects in the dog unknown but suspected.
  • Trauma, environmental damage, testicular neoplasia, systemic disease, ischemia, and heat stress-may cause transient infertility or sterility.
  • Prostatic disease-can markedly reduce semen quality and libido.
  • In-breeding-reduces fertility; reduced-fertility lines might only be salvaged by concerted breeding program and out-crosses with highly fertile animals.
  • Lymphocytic orchitis-familial in some breeds (e.g., beagles and borzois); affected animals may be fertile when young; accelerated rate of fertility loss with age.
  • Retrograde ejaculation-some retrograde flow into the bladder normal.

Risk Factors

  • Congenital disorders affecting reproductive function-not uncommon; tend to occur in selected breeds.
  • Teaser bitches and stud dogs not tested for infectious diseases (e.g., B. canis and bacterial culture of genital tract) before clinical use.

Diagnosis ⬆ ⬇

Diagnosis

Differential Diagnosis

Before extensive diagnostic work on the male, determine that the bitches are fertile (previous litters) and that the breedings were optimally timed (see Infertility, Female-Dogs, and Breeding, Timing).

CBC/Biochemistry/Urinalysis

  • Usually normal.
  • Brucellosis or prostatitis-variable changes in the leukogram (normal or leukocytosis) and urinalysis (high numbers of leukocytes); depends on the time-course of the infection; false negative Brucellosis test possible, antibiotic therapy may cause false negative
  • Systemic illness-may impair reproductive function, but infertility is usually not the primary complaint on examination.

Other Laboratory Tests

Endocrine Profile

  • Resting testosterone-normal, intact dogs, 0.4–10 ng/mL (1–4 ng/mL common range).
  • Androgenic tissue (detect bilaterally cryptorchid)-serum testosterone concentration increases 100% over the resting value 2–3 hours after injection with either 1–2 µg/kg GnRH or 40 IU/kg hCG; resting serum AMH.
  • Primary testicular failure-low testosterone and high FSH and LH.
  • Germinal compartment failure-normal testosterone and high FSH; FSH high due to the loss of inhibin secretion from viable Sertoli cells.
  • Hypogonadism-low testosterone, FSH and LH.
  • Thyroid function-evaluated by baseline T3 and T4, TSH values, and stimulation testing (see Hypothyroidism).
  • B. canis-screen with 2 mercaptoethanol rapid slide agglutination test (ME-RSAT); confirm with agar gel immunodiffusion test (AGID).

Imaging

Ultrasonography-identify lesions that alter the testicular and epididymal architecture (e.g., neoplasia, spermatocele, orchitis, epididymitis); evaluate the prostate gland for hyperplasia, chronic prostatitis, cyst, abscess, or neoplasia (see Prostate Disease in the Breeding Male Dog).

Diagnostic Procedures

Breeding Soundness Examination

  • Pivotal to ensure that all appropriate information is collected and must always consist of two semen collections.
  • Sperm-rich and prostatic portions of the ejaculate-collect as separate fractions by use of a sterile artificial vagina and sterile, graduated, non-toxic plastic tubes in the presence of an estrous bitch.
  • Sperm-rich fraction-volume; concentration, motility, and morphologic characteristics of sperm cells; cytologic examination; qualitative and quantitative cultures.
  • Prostatic fraction and urine-cytologic examination; qualitative and quantitative cultures.
  • Culture results-must be correlated with clinical and cytologic evidence of an active infection; evidence of inflammation if greater than 3–5 WBC/hpf observed (especially sperm-rich fraction).
  • Prostatic fraction that indicates a clinically important infection-reevaluate by other sampling techniques that avoid contamination from the penile mucosa and prepuce; negative cytology possible with chronic prostatitis.
  • Azoospermic or oligospermic ejaculate-recollect 1 hour later and again on several occasions before confirming infertility.

Epididymal Markers

ALP concentration in seminal fluid-normal 8,000–40,000 U/mL; epididymal in origin; may indicate obstruction if <5,000 U/mL and a complete ejaculate was obtained; pathologic effects of obstruction are more easily seen from ALP concentration if ALP is performed on two ejaculates collected 1 hour apart.

Pathologic Findings

  • Testicular biopsy-determines the degree of spermatogenesis and the integrity of the blood-testis barrier; differentiates obstruction of efferent ducts from testicular hypoplasia and degeneration; allows an informed prognosis.
  • Incisional biopsy-diagnostically superior to aspiration or needle biopsy; Bouin's fixative recommended for processing.

Treatment ⬆ ⬇

Treatment

Activity

  • Restrict if activity or use is thought to be producing hyperthermia (see Heat Stroke and Hyperthermia).
  • No restriction for other causes of infertility.

Diet

Ensure adequate diet and mineral supplementation; avoid supplementation of products containing excessive or undefined amounts of steroid hormones, e.g., extracts of testes, ovaries, and adrenals.

Client Education

  • Inform client that return to function may require at least 70 days from correction of identified cause(s).
  • Stress patience and check patient regularly to ensure that the condition is not worsening.

Surgical Considerations

Reanastomosis of blocked excurrent epididymal ducts (vasectomies) has been successful for re-establishment of sperm production.

Medications ⬆ ⬇

Medications

Drug(s) Of Choice

  • Specific medications must be administered at a dosage and time-course that ensures tissue penetration. Antibiotics (for penetration and spectrum)-chloramphenicol, trimethoprim-sulfa, erythromycin, and enrofloxacin; recommended for a minimum of 3–4 weeks to allow adequate and sustained levels within the reproductive tract.
  • Retrograde ejaculation-pseudoephedrine used with limited success in men, 4–5 mg/kg PO q8h, or 1 and 3 hours before collection; phenylpropanolamine, 4–8 mg/kg PO q24h, starting 5 days prior to collection.

Contraindications

  • Trimethoprim-sulfas-contraindicated if predisposed to keratitis sicca.
  • Chloramphenicol and trimethoprim-sulfas-reportedly induce blood dyscrasias.
  • Chloramphenicol-associated with anorexia and vomiting, but still may have the best tissue penetration.

Follow-Up ⬆ ⬇

Follow-Up

Patient Monitoring

Recheck at intervals that take into account the length of the spermatogenic cycle (70 days) but are frequent enough to allow detection of deteriorating condition.

Prevention/Avoidance

Avoid exposure to environmental temperature extremes (heat or cold).

Possible Complications

50–60% return to fertility after diagnosis and appropriate treatment.

Miscellaneous ⬆

Miscellaneous

Associated Conditions

  • Brucellosis infection-discospondylitis, polyarthritis, posterior paresis, fever, and uveitis.
  • Prostatic disease-obstipation, locomotor difficulties, fever, hematuria, pollakiuria, and dysuria.
  • Lymphocytic orchitis-lymphocytic thyroiditis.

Age-Related Factors

  • Daily sperm output and morphologically normal sperm cells decline with age.
  • Difficult to assess the effect of age alone on fertility.
  • Most old, infertile dogs have concurrent diseases (e.g., systemic or prostatic disease, testicular neoplasia, osteoarthritis) that have documented effects on fertility or libido.

Abbreviations

  • ALP = alkaline phosphatase
  • AMH = anti-müllerian hormone
  • FSH = follicle-stimulating hormone
  • GnRH = gonadotropin-releasing hormone
  • hCG = human chorionic gonadotropin
  • hpf = high power field
  • LH = luteinizing hormone
  • TSH = thyroid stimulating hormone
  • WBC = white blood cell

Author Richard A. Fayrer-Hosken

Consulting Editor Sara K. Lyle

Client Education Handout Available Online

Suggested Reading

CLopate . The problem stud dog. Vet Clin North Am Small Anim Pract 2012, 42(3):469–488.