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July 2015

Ox, Aubrac: Nasal mucosa, rhinitis, severe, chronic-active, multifocal, eosinophilic and granulomatous, with myriads of protozoal cysts (consistent with Besnoitia besnoiti)

05_15

History:  

Ox, Aubrac, 2.5 years, male

Diagnosis:   

Nasal mucosa, rhinitis, severe, chronic-active, multifocal, eosinophilic and granulomatous, with myriads of protozoal cysts (consistent with Besnoitia besnoiti)

Description:  

The nasal mucosa is covered by myriads of whitish granulomas of < 0.1 cm in diameter.

Comments:

The ox presented clinically with multifocal skin alterations involving the thighs, croup, muzzle, and scrotum. The pathologic examination revealed a severe chronic hyperkeratotic dermatitis and a massive lymphoid hyperplasia of several lymph nodes, along with granulomatous changes in the nasal cavity and in the sclera. Histologically, severe granulomatous and eosinophilic dermatitis, rhinitis, scleritis, periorchitis, and epididymitis with characteristic Besnoitia cysts were confirmed.

Besnoitiosis is the cause of severe systemic disease mainly in cattle and horses. It is caused by several host-specific species of the genus Besnoitia, belonging to the family Sarcocystidae. Besnoitia has a two-host life cycle with felids being the definitive hosts, and in case of Besnoitia besnoiti the intermediate host is the bovine. The characteristic histopathological findings are Besnoitia cysts composed of four distinct layers: 1. Condensed hyalinized layer of collagen; 2. Hyaline extracellular capsule; 3. Host cell with peripheralized nuclei; 4. Parasitophorous vacuole filled with 3-5 µm bradyzoites. When cysts rupture, granulomatous and eosinophilic inflammation results.

Picture by: Angele Breithaupt,  Authored by: Stephanie Plog,

Department of Veterinary Pathology, Freie Universität Berlin