Disease of the Scrotal Skin

Dermatitis

It has been often said that scrotal skin reacts just like the skin elsewhere, so it is not ‘special’. This is true, or at least is considered so. There is little point listing all the diseases of skin. Instead, the diseases that only affect scrotal skin, or have a predilectin for scrotal skin will be mentioned.

Bacteria

Dermatophilus congolensis

The scrotal skin of bulls is especially susceptible to infection by Dermatophilus congolensis. Severe, prolonged infection may result in thickening of the skin to 1 cm, with advanced testicular degeneration and infertility.

Virus

Poxvirus

Protozoa

Besnoitia besnoiti

Infection of scrotal skin by Besnoitia besnoiti also may lead to severe testicular degeneration. This infection is not limited to skin, and the small nodules containing white gritty material are seen grossly in the subcutis of the scrotum as well as in the tunics, the parenchyma of the testis, and in the epididymis. Vascular damage is important in the development of lesions, and large numbers of Besnoitia cysts may be present in the intima of vessels in the pampiniform plexus.

Kumi-Diaka J1, Wilson S, Sanusi A, Njoku CE, Osori DI. Bovine besnoitiosis and its effect on the male reproductive system. Theriogenology. 1981; 16: 523-530.

Trypanosomes

Metazoans - Insects and arthropods

Insects

Biting insects (Simuliidae and Culicoides) cause a local scrotal dermatitis in bulls.

Lice

Haematopinus eurysternus

Mites

Chorioptes bovis causes a scrotal dermatitis

Neoplasia

Neoplasia is rare in bulls, but papilloma, melanoma and hemangioma occur.

Physicochemical injury

Chemicals

Scrotal dermatitis is caused by contact with irritant substances from the environment.

Frostbite

Range bulls and occasionally rams, exposed to extreme cold may develop scrotal frostbite A higher incidence of lesions in old bulls is attributed to their more pendulous scrotums. Lesions are well demarcated regions of necrosis of skin on the ventral aspect of the scrotum and can involve up to 75% of the scrotum. Scrotal swelling, tunic adhesions, and decreased semen quality accompany the more severe lesions.

Varicose veins

Varicose dilations of scrotal veins occur in older bulls. They appear as flattened and irregular thickenings of the scrotal skin. The overlying epithelium usually is normal unless it ulcerates and bleeds. The affected venous channels are irregular in shape, widely dilated, and have thickened walls; thrombosis occurs in many.

Vaginal Tunics

Hernia

Scrotal hernia is rare in bulls.

Rush et al (2017) described one case.

Yepez et al (2021) reported on the surgical correction of 13 bulls with information gathered from 3 veterinary teaching hospitals. They all involved the left side.

Rush JB, Newcomer BW, Koziol JH, Maxwell HS, Wolfe DF. (2017) Theriogenology Question of the Month. J Amer Vet Med Assoc 2017; 250 379-382

Yepez PJ, Klabnik JL, Lozier JW, Niehaus AJ, Miesner MD, Prado TM, Anderson DE, Mulon PY. Surgical management and outcome of acquired inguinal hernias in mature bulls: 13 cases (2005-2017). J Am Vet Med Assoc. 2021; 259: 909-913.

Hydrocele

The cavity of the vaginal tunics communicates with the peritoneal cavity and is susceptible to the accumulation of ascitic fluid. Fluid within the cavity around the scrotal contents is called hydrocele. It forms for exactly the same reasons as ascites. Hydrocele may lead to severe testicular degeneration on the involved side and to a lesser extent on the opposite side. Scrotal hydrocele, with diminished sperm quality, is a herd problem in bulls in some regions. Clinically, the fluctuant nature of the enlarged scrotum, with a scrotal circumference up to 60 cm, is indicative of edema, and if affected bulls are examined at autopsy, there is obvious ascites. If hydrocele persists, the tunics become increasingly fibrotic. Ostertagiasis and hemotropic mycoplasma (Mycoplasma wenyonii) infection are incriminated as causes of this syndrome. Hydrocele in other species occurs with ascites of heart failure or any other cause of fluid buildup in the peritoneal cavity. It can also occur in conditions that cause edema of the scrotum (as listed above).

Sertoli cell tumors that obstructed vessels, and caused varicosities and hydrocele (McNeil and Weaver 1980).

Shore MD, Bretzlaff KN, Thompson JA, Magee DD. Outcome of scrotal hydrocele in 26 bulls .J Am Vet Med Assoc. 1995; 207: 757-760.

Hematocele

An accumulation of blood within the cavity of the vaginal tunics is haematocele. Local trauma is the most likely cause, but any disease or condition resulting in hemorrhage can be the cause.

Infection

Bacterial periorchitis

Family Bacillaceae Genus Bacillus

Bacillus anthracis

Friman et al (2019) reports on atypical anthrax in a young bull. It had a swollen scrotum and presumably periorchitis.

Friman M, Kakko L, Constantin C, Simojoki H, Andersson MA, Nagy S, Salonen H, Andersson M. An atypical Bacillus anthracis infection in a bull-A potential occupational health hazard. Reprod Domest Anim. 2019; 54: 1279-1283.

Protozoa

Severe periorchitis is a complication of epididymitis irrespective of cause, but is particularly found in bulls with Trypanosoma brucei infection,

Metazoa

A high occurrence of eosinophilic, then granulomatous, periorchitis in water buffaloes is attributed to Setaria sp. Periorchitis in rams is very common in infectious epididymitis. .

Setaria labiatopapillosa causes granulomatous periorchitis in bulls, and lesions occur particularly after adults are killed by anthelmintic treatment.

Neoplasia

Neoplastic disease involving the vaginal tunic is rare, even as secondary extension from the testis or scrotum.

Mesothelioma

Mesotheliomas with primary involvement of the vaginal tunic occur in the bull. Ultrastructural study or immunohistochemistry is necessary to differentiate mesotheliomas from metastatic adenocarcinoma. The origin of intrascrotal mesothelioma from the paramesonephric duct remnant is suggested.

Ladds PW, Crane CK. Scrotal mesothelioma in a bull. Aust Vet J. 1976; 52: 534-535.

Carcinoma - carcinomoatosis

Brakel et al (2018) reported on 2 separate bull calves that had scrotal swelling and abdominal distention. Each had metastatic carcinoma of the abdomen with involvement of the scrotum. Carcinomatosis can be difficult to distinguish from mesothelioma macroscopically, and immunohistochemistry and electron microscopy may be required to separate them.

Brakel KA, VanHoy G, Hinds A, Breitbach J, Premanandan C, Kohnken R. Peritoneal and scrotal carcinomas of unknown origin in two bovine calves. J Vet Diagn Invest. 2018; 30: 609-613.