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Basics ⬇

Outline

BASICS

Overview!!navigator!!

  • Phimosis is the inability of the horse to protrude the penis from the preputial orifice
  • It may be caused by congenital or acquired stenosis of the external preputial orifice or the preputial ring. Phimosis may be the result of a penile mass or swelling of the internal preputial lamina

Signalment!!navigator!!

  • Stallions or geldings of any age
  • Neonates and young foals with congenital stenosis or persistent attachment

Signs!!navigator!!

Historical Findings

Urination within the preputial cavity and/or dysuria.

Physical Examination Findings

  • Visible or palpable thickening of the external preputial orifice or the preputial ring. Excoriations due to urine scalding may be apparent
  • Longstanding cases may have a large accumulation of smegma and a nauseous odor

Causes and Risk Factors!!navigator!!

Congenital

  • Stenosis of the preputial orifice
  • Hermaphroditism
  • Penile dysgenesis

Acquired

  • Trauma—breeding injury, postsurgical edema, chronic posthitis
  • Neoplasia—sarcoid, SCC, papilloma, melanoma, hemangioma
  • Parasitism—habronemiasis
  • Viral infections—EHV-3
  • Poor hygiene; accumulation of excessive smegma can lead to posthitis and subsequent phimosis from the formation of scar tissue
  • Light-colored skin is associated with an increased incidence of SCC
  • Gray horses are more commonly diagnosed with melanomas

Diagnosis ⬆ ⬇

Outline

DIAGNOSIS

Differential Diagnosis!!navigator!!

Differentiating Similar Signs

Phimosis during the first 30 days of life is normally due to fusion of the internal preputial lamina to the free portion of the penis.

CBC/Biochemistry/Urinalysis!!navigator!!

N/A

Other Laboratory Tests!!navigator!!

Virus isolation using fluid from vesicular lesions may be diagnostic for EHV-3.

Imaging!!navigator!!

N/A

Other Diagnostic Procedures!!navigator!!

Cytology or biopsy (histopathology) may distinguish and/or provide a definitive diagnosis for neoplastic, granulomatous, or herpesvirus lesions.

Treatment ⬆ ⬇

TREATMENT

If phimosis is due to:

Medications ⬆ ⬇

Outline

MEDICATIONS

Drug(s) of Choice!!navigator!!

  • NSAIDs, including phenylbutazone (2–4 g/450 kg body weight/day PO) or flunixin meglumine (1.1 mg/kg/day IV, IM, or PO), for symptomatic relief or to decrease inflammation
  • Systemic or local antibiotics if indicated to treat local infections or prevent septicemia
  • Diuretics—furosemide (1–2 mg/kg IV every 6–12 h) may be indicated in the acute phase to reduce edema
  • Specific topical or systemic treatments for parasitic, fungal, or neoplastic conditions as indicated by test results

Contraindications Possible Interactions!!navigator!!

Phenothiazine tranquilizers should be avoided/used with caution in male horses.

Follow-up ⬆ ⬇

Outline

FOLLOW-UP

Patient Monitoring!!navigator!!

  • Initially, daily evaluations—ensure that secondary posthitis, balanitis, balanoposthitis, urine scald, or penile/preputial excoriations are not complicating the phimosis
  • As the initial problem is effectively treated, less frequent examinations will be necessary

Possible Complications!!navigator!!

  • Urination within the preputial cavity may cause inflammation of the epithelium, leading to a more extensive inflammation (posthitis, balanoposthitis) and scarring
  • Infertility or impotence can result if scarring becomes extensive

Miscellaneous ⬆ ⬇

Outline

MISCELLANEOUS

Associated Conditions!!navigator!!

N/A

Age-Related Factors!!navigator!!

  • Papillomas are more frequently diagnosed in young animals
  • SCCs and melanomas are more frequently diagnosed in middle-aged to aged horses

Zoonotic Potential!!navigator!!

N/A

Pregnancy/Fertility/Breeding!!navigator!!

N/A

Synonyms!!navigator!!

N/A

Abbreviations!!navigator!!

  • EHV = equine herpesvirus
  • NSAID = nonsteroidal anti-inflammatory drug
  • SCC = squamous cell carcinoma

Suggested Reading ⬆ ⬇

Schumacher J, Varner DD. Surgical correction of abnormalities affecting the reproductive organs of stallions. In: Youngquist RS, Threlfall WR, eds. Current Therapy in Large Animal Theriogenology, 2e. St. Louis, MO: Saunders Elsevier, 2007:23–36.

Schumacher J, Varner DD. Abnormalities of the penis and prepuce. In: McKinnon AO, Squires EL, Vaala WE, Varner DD, eds. Equine Reproduction, 2e. Ames, IA: Wiley Blackwell, 2011:1130-1144.

Author(s) ⬆

Author: Ahmed Tibary

Consulting Editor: Carla L. Carleton

Acknowledgment: The author and editor acknowledge the prior contribution of Carole C. Miller.