section name header

Basics ⬇

Outline

BASICS

Definition!!navigator!!

Clinically visible increased scrotal size due a process involving the scrotum or its content (testes, epididymides, blood supply). The enlargement may be bilateral or unilateral. Clinic and systemic signs are variable and depend on the cause.

Pathophysiology!!navigator!!

  • The equine scrotum and associated contents are relatively well protected. The scrotum is almost symmetrical and covered with a think pliable skin with freely movable content
  • Scrotal enlargement may appear acutely or progressively
  • Acute scrotal enlargement is more common and often due to trauma (breeding accident, jumping), spermatic cord torsion, inguinal/scrotal herniation, or inflammatory processes (epididymitis, orchitis)
  • Trauma can result in scrotal hemorrhage, edema, rupture of the tunica albuginea, hematocele
  • Progressive enlargement of the scrotum is often due to vascular abnormalities or poor thermoregulation (poor lymphatic drainage, edema, hydrocele) or neoplasia
  • Scrotal enlargement may be observed following abdominal surgery

Systems Affected!!navigator!!

Reproductive

Genetics!!navigator!!

N/A

Incidence/Prevalence!!navigator!!

Scrotal enlargement due to trauma is the most common presentation in breeding stallions.

Signalment!!navigator!!

  • Intact male horses
  • Inguinal hernia is a common cause of scrotal enlargement in foals

Signs!!navigator!!

Historical Findings

  • Gross changes in the size of the scrotum (usually acute)
  • Pain (generally colic-like symptoms)
  • Reluctance to breed, jump, or walk
  • Extreme environmental temperatures (hot or cold)

Physical Examination Findings

  • Increased scrotal size (unilateral or bilateral)
  • Abnormal testicular position
  • Abnormal scrotal temperature (too warm or cold)
  • Edema/engorgement of scrotum and/or contents
  • Scrotal lesions (laceration, abscesses, neoplasia)
  • Pain may be elicited on palpation (spermatic cord torsion, epididymitis, orchitis, rupture)
  • Derangements in systemic parameters (elevated heart rate, respiratory rate, inappetence, CBC abnormalities)
  • Any combination of abnormalities may be present and not all signs are present in every animal

Causes!!navigator!!

  • 3 most common:
    • Trauma; may include testicular hematoma/rupture
    • Inguinal/scrotal hernia
    • Torsion of the spermatic cord, also known as testicular torsion
  • Inflammatory/infectious causes:
    • EIA
    • EVA/equine arteritis virus
    • Orchitis/epididymitis
  • Neoplasia:
    • Primary scrotal—melanoma, sarcoid
    • Testicular neoplasia—seminoma, teratoma, interstitial cell tumor, Sertoli cell tumor
  • Noninflammatory scrotal edema
  • Hydrocele/hematocele
  • Varicocele

Risk Factors!!navigator!!

  • Breeding activity
  • Large internal inguinal rings
  • Systemic illness
  • Extremes of ambient temperature (hot or cold)

Diagnosis ⬆ ⬇

Outline

DIAGNOSIS

Differential Diagnosis!!navigator!!

Differentiating Causes

  • Duration of problem
    • Acute—traumatic injury, torsion of spermatic cord, herniation, infection
    • Chronic—neoplasia, temperature-induced hydrocele/edema, varicocele, infection
  • History of recent breeding, semen collection, and/or trauma
  • Palpation of the caudal ligament of the epididymis (attaches epididymal tail to caudal testis and aids in the determination of testicular orientation)
  • Palpation of the inguinal rings
  • US (see Imaging)

CBC/Biochemistry/Urinalysis!!navigator!!

  • Inflammatory or stress leukocyte response
  • Increased fibrinogen
  • Results of serum biochemistry profile and urinalysis are usually normal

Other Laboratory Tests!!navigator!!

  • EVA
    • Serum neutralization or complement fixation
    • Acute and convalescent serum samples
    • If stallion is seropositive, carrier state is determined with virus isolation
    • Virus isolation from serum and/or seminal plasma
    • Semen is the best sample for diagnosis (freeze portion of ejaculate and send to approved laboratory along with serum samples)
    • Send samples to an approved laboratory
  • EIA
    • Agar gel immunodiffusion or ELISA, the Coggins test

Imaging—scrotal Us!!navigator!!

Examination of scrotal contents may reveal:

  • Bowel with inguinal/scrotal herniation
  • Rupture of the testis/tunica albuginea
    • Accumulation of hypoechoic fluid in scrotum with loss of discrete hyperechoic tunica albuginea around testicular parenchyma
    • Hypoechoic appearance of contents will gradually contain echogenic densities with the formation of fibrin clots
  • Engorgement of the pampiniform plexus and/or testicular congestion with torsion of the spermatic cord
    • Doppler can verify loss of blood flow to the testis
  • Hypoechoic dilation of venous plexus of spermatic cord with varicocele
  • Hypoechoic accumulation of fluid within the vaginal cavity with hydrocele
  • Loss of homogeneity in testicular parenchyma with neoplasia
    • May see areas of increased or decreased echogenicity or be variable throughout

Other Diagnostic Procedures!!navigator!!

  • Needle aspirate and cytology—to differentiate hydrocele from recent hemorrhage
  • Neoplasia—diagnosed using fine needle aspirate and/or biopsy

Pathologic Findings!!navigator!!

Dependent on etiology.

Treatment ⬆ ⬇

Outline

TREATMENT

  • Treatment is directed at the cause of scrotal enlargement
  • Management of inflammation is a primary concern with abnormal scrotal enlargement
  • Sexual rest is indicated for all causes of scrotal enlargement

Appropriate Health Care!!navigator!!

  • Acute scrotal enlargement warrants hospitalization for treatment and care
  • Chronic scrotal enlargement may or may not warrant hospitalization; etiology dependent

Nursing Care!!navigator!!

  • Cold therapy (cold packs, ice water baths, water hose/hydrotherapy) for acute scrotal trauma is implemented only in the absence of testicular rupture
    • Testicular tunics must be intact
    • Cold therapy sessions should not exceed 20 min and can be repeated every 2 h
  • Scrotal massage with emollient salve—useful to reduce scrotal edema and ischemic injury
  • Fluid removal should be considered with a hydrocele
    • Use only an aseptically placed needle or an IV catheter
    • Excess fluid accumulation may cause thermal damage to the testes, acts as an insulator
  • Administration of IV fluids is dependent on the systemic status of the horse

Activity!!navigator!!

The need to restrict activity depends on the etiology of scrotal enlargement.

Diet!!navigator!!

Diet modification is necessary only with secondary ileus or as a preoperative consideration.

Client Education!!navigator!!

  • Fertility may be irreversibly impaired with acute scrotal trauma
  • Semen evaluation should be performed 90 days after nonsurgical resolution of scrotal enlargement
  • Compensatory semen production may occur in the remaining testis of a horse undergoing hemicastration
  • Following removal of a neoplasia, examine carefully for evidence of metastatic tumor growth (serial examinations)

Surgical Considerations!!navigator!!

  • Hemicastration is the treatment of choice for:
    • Torsion of the spermatic cord, if the duration of vascular compromise has caused irreversible damage and/or gonadal necrosis
    • Unilateral inguinal/scrotal herniation
    • Testicular rupture
    • Unilateral neoplasia
    • Varicocele
    • Nonresponsive hydrocele/hematocele
  • Primary repair of scrotal laceration is required to protect scrotal contents
    • Repair generally fails due to extensive scrotal edema associated with traumatic injury

Medications ⬆ ⬇

Outline

MEDICATIONS

Drug(s) of Choice!!navigator!!

  • Anti-inflammatory therapy (phenylbutazone 2–4 mg/kg PO or IV BID or flunixin meglumine 1 mg/kg IV BID) is indicated in all cases
  • Diuretics (furosemide 0.5–1 mg/kg IV) may be useful in managing scrotal edema
  • Antibiotic therapy should be considered in cases of scrotal laceration or scrotal hemorrhage
  • Tetanus toxoid should be administered for scrotal trauma or prior to surgery

Contraindications!!navigator!!

N/A

Precautions!!navigator!!

N/A

Possible Interactions!!navigator!!

N/A

Alternative Drugs!!navigator!!

N/A

Follow-up ⬆ ⬇

Outline

FOLLOW-UP

Patient Monitoring!!navigator!!

Semen collection and evaluation 90 days after complete resolution of cause and/or surgery.

Prevention/Avoidance!!navigator!!

Adequate management of breeding to avoid trauma.

Possible Complications!!navigator!!

  • Infertility
  • Endotoxemia
  • Laminitis
  • Scrotal adhesions
  • Death

Expected Course and Prognosis!!navigator!!

  • Prognosis for survival and fertility are good in unilateral cases of trauma or spermatic cord torsion if managed quickly and correctly
  • Recurrent severe hematocele; hydrocele may result in testicular degeneration and loss of fertility

Miscellaneous ⬆ ⬇

Outline

MISCELLANEOUS

Associated Conditions!!navigator!!

N/A

Age-Related Factors!!navigator!!

N/A

Zoonotic Potential!!navigator!!

N/A

Pregnancy/Fertility/Breeding!!navigator!!

N/A

Synonyms!!navigator!!

N/A

Abbreviations!!navigator!!

  • EIA = equine infectious anemia
  • ELISA = enzyme-linked immunosorbent assay
  • EVA = equine viral arteritis
  • US = ultrasonography, ultrasound

Suggested Reading ⬆ ⬇

Gonzalez M, Tibary A, Sellon DC, Daniels J. Unilateral orchitis and epididymitis caused by Corynebacterium pseudotuberculosis in a stallion. Equine Vet Educ 2008;20:30–36.

Morresey PR. The enlarged scrotum. Clin Tech Equine Pract 2007;6265–6270.

Threlfall WR, Carleton CL, Robertson J, et al. Recurrent torsion of the spermatic cord and scrotal testis in a stallion. J Am Vet Med Assoc 1990;196:1641–1643.

Tibary A, Chabchoub A, Sghiri A. Diagnostic procedures for an increase in volume of the scrotal bursa in stallion. Le Nouveau Praticien Veterinaire—Equine 2007;14:21–27.

Van der Velden MA. Surgical treatment of acquired inguinal hernia in the horse: a review of 51 cases. Equine Vet J 1988;20:173–177.

Author(s) ⬆

Author: Ahmed Tibary

Consulting Editor: Carla L. Carleton

Acknowledgment: The author and editor acknowledge the prior contribution of Margo L. Macpherson.