Clinico-pathological studies on experimental cryptococcal mastitis in goats

Unilateral intramammary inoculation of 10 goats with Cryptococcus neoformans (2 x 10(6) yeast cells) resulted in the development of mastitis, with gross and microscopic lesions being restricted to the infected udder halves only and there was no dissemination of infection to the opposite uninfected udder halves as well as to other organs of the body. The experiment was continued for 40 days, with 2 animals each from the infected and control groups being killed on 5th, 10th, 20th, 30th and 40th day post-inoculation (DPI). Initial enlargement of the infected udder halves was followed by marked decrease in size leading to very small, firm and nodular udder halves. After infection, there was also sharp fall in the milk yield. Cryptococcal organisms were demonstrated in the mastitic milk and udder impression smears with special stains. C. neoformans was reisolated from the milk of the only infected udder halves up to 25th DPI. Microscopically, there was initially acute diffuse purulent mastitis which later on became chronic, characterised by marked infiltration of lymphocytes, macrophages, extensive fibrosis and development of multiple granulomas. The cryptococcal organisms could be demonstrated in the udder sections only up to 30th DPI. It is concluded that intramammary inoculation of Cryptococcus neoformans in goats leads to severe mastitis with sharp fall in milk yield.