Merck Manual

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Enzootic Posthitis and Vulvitis in Sheep and Goats

(Sheath Rot, Pizzle Rot, Enzootic Balanoposthitis, Ulcerative Posthitis)


John WA Larsen

, BVSc, PhD, Faculty of Veterinary and Agricultural Sciences, University of Melbourne

Reviewed/Revised Nov 2020 | Modified Oct 2022
Topic Resources

Enzootic posthitis and vulvitis is principally a disease of castrated males (wethers) fed high-protein diets (eg, grazing lush pastures). Initially, small ulcers develop that may coalesce and eventually (weeks or months later) cause partial or complete obstruction of the prepuce. Clinical signs include inflammation, discomfort, kicking at the belly, and pooling of urine in the prepuce. Lesions can be highly attractive to oviposition by flies, which leads to "pizzle strike." Treatment should include cleaning and debridement, flushing with dilute antiseptic solution, and (when appropriate) application of insecticide to prevent secondary flystrike. Testosterone compounds (if allowed in a jurisdiction) can be used for treatment and prevention (eg, testosterone ethanate).

Etiology and Epidemiology of Enzootic Posthitis and Vulvitis in Sheep and Goats

Enzootic posthitis and vulvitis is a moderately contagious disease caused by Corynebacterium renale, a gram-positive, diphtheroid bacterium capable of hydrolyzing urea. When protein intake is high, urinary urea concentration increases. Hydrolysis of urea by C renale results in local production of large quantities of ammonia, which is believed to irritate the penis, lamina interna of the prepuce, and skin surrounding the preputial orifice. The condition is more common in male castrates, probably because of the hypoplastic nature of the penis, exacerbated in some cases by failure of penile-preputial separation that leads to pooling of urine in the prepuce. If preputial hair is cut too short or becomes caked with mud or organic matter, drainage of urine away from the preputial orifice (normally facilitated by this hair) is impaired, and ulcerative lesions may develop.

The incidence of ulcerative posthitis is highest in Merino and Angora wethers, which is attributed to the long hair or wool surrounding the prepuce in these animals, allowing urine to soak the area, which in turn is conducive to bacterial growth and activity. It is also seen in show rams or rams that have been prepared for sale; in this case, the condition is more associated with dietary protein levels. The condition can be transmitted experimentally by infective material from a preputial or vulvar ulcer. Ulcerative posthitis or vulvitis has a seasonal occurrence that varies with local animal husbandry methods. Peak incidence corresponds to the time when animals graze lush green pasture (eg, spring and early summer in cool, temperate areas with winter-dominant rainfall, such as New Zealand, or autumn and winter in southern Brazil) or are fed or have access to high-protein feedstuffs.

Clinical Findings of Enzootic Posthitis and Vulvitis in Sheep and Goats

In mild cases, signs of enzootic posthitis and vulvitis are limited to swelling of the prepuce. In severe cases, swelling and inflammation interfere with urination and result in pooling of urine in the prepuce and straining, which needs to be differentiated from urolithiasis Urolithiasis in Ruminants Obstructive urolithiasis is a significant cause of morbidity and mortality in male ruminants. Uroliths form from protein and mineral components of the diet. They develop in the urinary bladder... read more Urolithiasis in Ruminants . Histologic characteristics are acanthosis, parakeratosis, and hyperkeratosis, followed by leukocyte invasion and ulceration. Ulcers and scabs may be found around the preputial orifice, on the lamina interna of the prepuce, and on the shaft of the penis. Urine and exudate may accumulate in the prepuce. The condition may cause severe discomfort. If the preputial orifice or urethra is occluded, affected animals may die. Ulcerative vulvitis begins with signs of vulvar inflammation, including swelling and redness, and progresses to development of a yellow exudate with ulceration and scab formation around the vulva, vestibule, and caudal vagina. The glans clitoridis may be swollen, red, and ulcerated.

Lesions of ulcerative posthitis or vulvitis should be distinguished from those of granular posthitis or vulvitis Vulvitis and Vaginitis in Large Animals (associated with Mycoplasma spp or Ureaplasma spp), herpesviral balanoposthitis or vulvovaginitis, or contagious ecthyma Contagious Ecthyma in Sheep and Goats Contagious ecthyma is an infectious dermatitis of sheep and goats that primarily affects the lips of young animals. The lesions are characteristic, and diagnosis is confirmed by PCR assay. The... read more Contagious Ecthyma in Sheep and Goats (orf, goats only). Removal of the scabs of ulcerative posthitis or vulvitis characteristically results in little or no hemorrhage.

Treatment and Control of Enzootic Posthitis and Vulvitis in Sheep and Goats

  • Severe cases can be debrided and treated with antiseptics

  • Insecticides control secondary flystrike and testosterone (if permitted) can also be used as preventives

If possible, animals with enzootic posthitis and vulvitis should be isolated from the rest of the flock and not fed a high-protein diet. Lesions should be examined to ensure they do not interfere with urethral patency. Clipping and cleaning hair around the prepuce and flushing with a dilute antiseptic solution may be beneficial. C renale is usually sensitive to penicillins and cephalosporins, which may be beneficial if practical. Ulcerative posthitis is controlled principally by limiting dietary protein to a level consistent with requirements. If untreated, scarring may be so severe that the penis cannot be extended.

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