Diseases of the Testes and Scrotum

Chapter 86 Diseases of the Testes and Scrotum



Thomas K. Graves


A number of congenital and acquired diseases affecting the testes and scrotum are commonly recognized in small animal patients. Traumatic, infectious, and inflammatory diseases of the testes or scrotum are less common but may result in discomfort to the patient warranting presentation. Most dogs with testicular diseases have no clinical signs with the exception of infertility in breeding dogs.



DISEASES OF THE TESTES



Etiology



Congenital Disorders



Cryptorchidism



• Cryptorchidism is a common hereditary disorder in which one or both testicles fail to descend to the normal scrotal position. The disorder is recognized in both dogs and cats and is a sex-linked autosomal recessive trait.

• In dogs, toy breeds, boxers, and German shepherds are predisposed; in cats, the Persian breed is predisposed.

• In dogs, testicular descent occurs by 10 days of age, but it may be delayed 8 weeks or longer.

• Cryptorchid testes may be located within the abdominal cavity, within the inguinal ring, or subcutaneously in the prescrotal region.

• Unilateral cryptorchidism is more common than bilateral (75%).

• Dogs with bilateral cryptorchidism are sterile, whereas those with unilateral cryptorchidism are fertile. Undescended testicles are abnormal and have abnormal spermatogenesis because of the exposure to high body temperature.

• Even sterile dogs with cryptorchidism have normal libido, and male characteristics because testosterone secretion from interstitial cells is preserved.



Key Point


Perform bilateral orchiectomy (see Chapter 87) for all cryptorchid animals to eliminate the potential risk of testicular neoplasia, male feminizing syndrome, and testicular torsion and because it is a hereditary disorder.



Male Pseudohermaphroditism



• Affected dogs have testes, and XY chromosomes, but have external or internal female genitalia.

• The testes are hypoplastic and cryptorchidism is common.

• Abnormalities in the development of the prepuce and penis may also be noted.


Testicular Feminization Syndromes



• These dogs or cats have XY chromosomes but have partial or complete failure of masculinization.

• The syndrome is due to X-linked mutations in the androgen receptor gene.

• There can be a certain degree of testicular development in some animals. Others, although male, can be phenotypically female with no noticeable testicular development.


XX Sex Reversal


This chromosomal abnormality is associated with testicular abnormalities, as well as other genital malformations in dogs. (See Chapter 88.)



Acquired Disorders of the Testes



Orchitis-Epididymitis



Infectious Orchitis-Epididymitis


• Infection of the testes and epididymis can come from penetrating wounds, can be acquired hematogenously, or can come from spread of infections of the urogenital tract, including the prostate.

• Aerobic bacteria are most common.

• Brucella canis is an important cause of orchitisepididymitis.

• Mycoplasma organisms have been implicated.

• Viral causes of orchitis-epididymitis include canine distemper virus and feline infectious peritonitis.

• Blastomyces organisms can be implicated in endemic areas.

• Rickettsial infections such as ehrlichiosis and Rocky Mountain spotted fever can be associated with testicular or epididymal infection.


Immune-Mediated Orchitis


• Normally, the blood-testis barrier prevents immune responses to spermatozoal antigens.

• When this barrier is disrupted, orchitis can ensue, and it is associated with lymphocytic infiltration of the testes and infertility.


Testicular Neoplasia



• Testicular tumors are relatively common in dogs and uncommon in cats.

• Primary testicular tumors include Sertoli cell and interstitial cell tumors and seminoma.

• Testicular neoplasia is 9.6% to 13.6% more likely in cryptorchid patients due to prolonged exposure of the retained testicle to normal body temperatures.
• The contralateral descended testicle demonstrates the same neoplastic cells in 40% of the cryptorchid dogs.

• Testicular neoplasia is rarely seen in cryptorchid cats.

• Most testicular tumors in dogs are so slowly metastatic as to be considered benign.

• Most testicular tumors in non-cryptorchid dogs are incidental findings in older patients. Intra-abdominal testicular tumors are usually suspected based on age, signs of hyperestrogenism or hypertestosteronism, and history of cryptorchidism.

• Sertoli cell tumors can result in male feminizing syndrome including hair loss (see Chapter 51), gynecomastia, hematologic abnormalities, testicular atrophy, and squamous metaplasia of the prostate.


Trauma



• Trauma to the testes and scrotum can lead to chronic orchitis-epididymitis or ischemia, so prompt attention to testicular trauma is necessary.


Testicular Torsion



• Testicular torsion can occur in cryptorchid or normal testes and is associated with acute onset of pain.

• Torsion results in swelling of the testicle and spermatic cord due to complete or partial obstruction of arterial blood flow and venous drainage.


Secondary Testicular Disorders



• Testicular dysfunction and infertility can occur secondary to endocrine diseases such as hyperadrenocorticism, diabetes mellitus, and hypothyroidism.

• A full metabolic evaluation is useful for dogs presenting for infertility.


Other Testicular Diseases



• Sperm granuloma can develop when sperm cells accumulate in the spermatic ducts, and a chronic inflammatory response ensues.

• Spermatocele is a sperm-containing dilation of the duct system and is considered a benign lesion.

• Varicocele is a dilation of the spermatic vein, which can lead to thrombosis but may also be a benign lesion.


Clinical Signs



• In some animals with testicular diseases, no clinical signs are noticed by the owner.

• Infertility is a common clinical sign.


Orchitis-Epididymitis



• Infection, trauma, or immune-mediated disease can cause pain and inflammation of the testes.
• Animals may have scrotal swelling and a stiff gait. Frequent licking of the scrotum may be observed.

• Infectious disease of the testes can involve other components of the urogenital system, so clinical signs of prostatic disease (e.g., straining to urinate or defecate) can be present, as can signs of lower urinary tract infections (hematuria, stranguria, pollakiuria).

• Testicular inflammation can be associated with systemic signs of inflammation (e.g., depression, anorexia, and fever).


Neoplasia



• Estrogen from Sertoli cell tumors can result in feminization (testicular atrophy, infertility, gynecomastia), bone marrow suppression, alopecia (see Chapter 51), and squamous metaplasia of the prostate. Testosterone from interstitial cell tumors can result in prostatic hypertrophy, perianal adenoma, and other androgen-dependent changes. Seminoma has also been associated with hyperestrogenism.

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Aug 27, 2016 | Posted by in SMALL ANIMAL | Comments Off on Diseases of the Testes and Scrotum

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