Chapter 6 Infertility in the Male Dog

 

 

6.1 Definition:

In ability to breed or produce a successful pregnancy . Characteristics of a fertile Male Dog

• 1.Capable of producing adequate number of normal spermatozoa in the testicles.
• 2. Have the ductal system capable of delivering spermatozoa.
• 3. Be capable of ejaculation
• 4. Have spermatozoa that can be "capacitated" in the female dog to penetrate the zona pellucida of the egg surface. 

6.2 Cause:

There are generally three causes of infertility in the male dog

• A. Pregeminal causes - hypothalamic or pituitary lack of gonadotropin releasing hormone (GnRH), FSH, or LH.
• B. Germinal causes - failure to respond to FSH or LHu.

Postgerminal causes - Blockage of the duct system 

6.3 History

• A. In order to determine the cause of infertility in the male dog an adequate history must be taken
• 1. Is there infertility in the pedigree?
• 2. Has the dog ever produced any pregnancies?
• 3. Does the male dog appear to have a normal libido?
• 4. Did the owner ever see the breeding?
• 5. Did the breeder observe a tie?
• 6. What is the pedigree relation of this male and the bitches to which he has been bred?
• 7. How frequently is the male used for breeding?
• 8. Has the dog had any febrile illness within the last months?
• 9. Has the dog had any symptoms of dysuria. pollakiuria or hematuria?
• 10. Has the male dog been tested for brucellosis recently?
• 11. Where is the dog housed?
• 12. Is the dog being heavily campaigned on the show circuit? When was he last sent out with a professional handler? 
• 13. Is the male dog receiving medication of any kind? 
• 14. Is there a history of extrareproducitve endocrine disease? 
• 15. Have the bitches he has bred been proved to be fertile? Have they had previous litters? 
• 16. To the owner's knowledge, is the dog ever had any orchitis epididymitis, scrotal swelling etc. ?
• 17. Has the previous laboratory testing of semen been done? What were the results?
  • a. How many semen evaluations have been performed over what interval of time?
  • b. Semen evaluations need not be performed more often than once every 60-70 days in the dog.
  • c. If an aspermic dog began normal spermatogenesis today, those spermatozoa would not be ejaculated for approximately 2 months
• 18. Does the owner/breeder have a good knowledge of canine reproductive physiology? In other words, are the bitches being bred at adequate and appropriate intervals to achieve conception? 

6.4 Physical Examination

• A. General physical examination
• B. Reproductive examination 
  • 1. Scrotum - the scrotum should be usually evaluated _and palpated. 
    • a. The scrotum is checked for evidence of trauma or adhesions to the testes.
    •  b. modules in the scrotum might suggest malignancy.
      • i. Mast cell tumors, squamous cell carcinomas melanomas
      • ii. Tumors of the scrotum may extend to the adjacent testicle. 
  • 2. Testicles - the testes should be palpated and evaluated 
    • a. Both testes should be present in the scrotal sac.
      • i. Testicular descent should be complete by 3 weeks in the dog.
      • ii, Bilaterally cryptochid dogs are infertile. 
    • b. Testicles should be evaluated for .~i~e and consistency.
      • i. Hard nodules within the testes are suggestive of neoplasia.
      • ii. Small soft testicles are found in senile atrophy.
      • iii. The testes are usually swollen and firm with acute orchitis.
      • iv. The testes are usually atrophied and firm with chronic orchitis.
  • 3. Spermatic cords should be traced by palpation from the caudal testis to the inguinal ring. 
  • 4. Prostate - the prostate should be evaluated by rectal palpation of the gland.
    • a. enlargement may indicate either benign hypertrophy or inflammation.
    • b. the urinary tract should be evaluated and prostatic wash performed with enlargement.
  • 5. Penis - the penis should be extruded as completely as possible from the sheath and examined for traumatic esions. tumors, inflammation, etc. 

6.5 Diagnosis

6.5.1 Signalment 

1. Age

• a. Ejaculates from medium sized dogs do not contain normal spermatozoa until they are 1 year of age.
• b. Large breeds continue to show abnormal spermatozoa until they are 15-18 months old.
• c. The American kennel Club refuses to register litters sired by male dogs older than 12 years. However senile changes in large breeds begin at 6 years of age.

6.5.2 Breed

Male dogs of some breeds characteristically have difficulty naturally breeding due to their conformation

6.5.3 Diagnostic testing

• 1. CBC, Biochemical profile
• 2. Brucella canis serology
• 3. Urinalysis and urine culture if indicated
• 4. T evaluation and/or TSH response test
• 5. FSH, LH and testosterone evaluation
  • a. Elevated FSH and aspermia means primary germinal hypoplasla.
  • b. Low FSH, LH, and testosterone and aspermia may indicate a pregerminal lesion.
  • c. Normal FSH, LH, and testosterone levels with aspermia are suggestive of a postgerminal -obstructive defect, retrograde ejaculation or transitory arrest of spermatogenesis.
  • 6. Semen evaluation
  • 7. Testicular aspiration or biopsy

6.5.4 Differential diagnosis

6.5.4.1 Congenital infertility

• a. Endocrine problems
  • i. Panhypopituitarism - congenitally low or absent FSH and LH
  • ii. Hypothyroidism - associated with depressed gonadotropic function. lowered steroid synthesis rates, and hence deficient spermatogenic function
• b. Chromosomal abnormalities
  • i. Klinefelter's syndrome - doubling of the usual number of chromosomes (79XXY)
  • ii. hartagener's syndrome - produces defects in the ciliated cells in the body and defects in spermatozoal motility is also noted
• c. Anatomic defects
  • i. Bilateral cryptochidism
  • ii. Persistent penile frenulum
  • iii. Shortened os penis
  • iv. Segmental aplasia of the ductus deferens or epldidymis v. "Sertoli cell only syndrome" - no evidence of spermatogonia in the testicle
• d. Retrograde ejaculation - failure of closure of the. internal bladder sphincter. Semen flows by gravity into the bladder. Sympathomimetic agents have been tried to close the internal sphincter to achieve antegrade ejaculation

6.5.4.2 Acquired infertility

• a. Endocrine abnormality
  • i. Tumors of the hypothalamus or adenohypophysis
  • ii. Hypothyroidism
  • iii. Hyperadrenocorticism
  • iv. Hypoadrenocorticlsm
• b. Metabolic diseases
  • i. Chronic uremia - impaired Leydig cell function
  • ii. uhronic iiver disease - testicular atrophy
• c. Stress - methods not clearly defined
• d. Febrile illness - chronic warming of the scrotal sac to 104 degrees Fahrenheit for 5 days
• e. Environmental alterations
  • i. Excessive kenneling
  • ii. Psychological changes
  • iii. High ambient temperatures
• f. Infection
  • i. Brucellosis
  • ii. Prostatic infection may predispose to urethritis, epididymitis, or orchitis
• g. Acquired anatomic defects
  • i. obstruction of the ejaculatory ducts due to epididymitis
  • ii. fracture of os penis or phimosis
• h. Overuse ?
• i. Testicular neoplasia
• j. Prior hormonal treatment
• k. Testicular torsion
• l. Retrograde ejaculation
• m. Immune-mediated infertility
• n. Drug induced infertility - alkylating agents, antimetabolites, nitrofurantoin, cimetidien. and azulfidine are agents that can cause temporary or permanent infertility. Semen banks may be used.
• o. Obesity - leads to alteration in serum estradiol and testosterone levels 

6.6 Treatment

• A. Fertility is restored in only a small percentage of cases.
• B. Definitive diagnosis of male fertility is difficult so treatment is usually empirical.
• C. A complete work-up is necessary prior to treatment any with hormonal agents.
• G. Due to the development and transport of spermatozoa takes about 75 days therapy should be given for 2-3 months before expecting any improvement.