MSUD (Maple Syrup Urine Disease) in Polled Hereford and Polled Hereford x Shorthorn crosses in calves in Uruguay

Abstract

Maple Syrup Urine Disease (MSUD) was diagnosed in Polled Hereford and Polled Hereford x Shorthorn calves from three commercial herds in the East Region of Uru­guay. Three calves (2.3%) were affected in a purebred Polled Hereford herd in August 2004, 5 (4.1%) in a pure­bred polled Hereford cows in September 2006, and 7 (3.8%) in a Polled Hereford x Shorthorn herd in August 2008. All three herds were bred with Uruguayan Polled Hereford bulls. Affected calves were normal at birth but after weaning developed a severe neurologic condition characterized clinically by extensor spasms, depression, opisthotonos and inability to stand, dying within 3-5 days of birth. The principal histopathologic change in 3 affected calves was diffuse, severe, status spongiosus throughout the white matter of the cerebellum, cerebrum, mesenceph­alus and medulla oblongata, and less so in spinal cord. Spongiosis was due to edema of myelin sheaths. Myelin deficits or neuronal death were not found. Blood samples from 1 bull and 5 cows (37.5%) from herd 2, and 1 bull, 2 cows (28.5%) and the affected calf from herd 3, were identified as carriers for the MSUD 248C→T mutation. The mutation seems to be widespread in Polled Hereford herds in Uruguay.