GENERALIZED AA-AMYLOIDOSIS IN SIAMESE AND ORIENTAL CATS

During a 7 year period (1987-1994), 194 Siamese cats including a colou r variant designated Oriental cat, were presented for post-mortem exam ination. Twelve of these animals (6.2%) were diagnosed with amyloidosi s. Major gross pathological findings included enlarged pale livers wit h haemorrhages, pale and swollen spleens, and dilated intestines. Depo sits of amyloid were found in these tissues. The amyloid was found to cross-react with anti dog AA-antiserum when examined with peroxidase a ntiperoxidase (PAP) staining (four cases). Amyloid fibrils were purifi ed by the water extraction method and its major constituting protein ( AA) was isolated by gel filtration. Amino acid sequence analysis of th is protein from a Siamese cat and an Abyssinian cat revealed a signifi cant difference between these breeds. In the Siamese protein AA two am ino acid substitutions (46 R for Q and 52 V for A) were encountered. T his finding indicates the existence of a new feline amyloid A protein occurring in the Siamese breed which differs from presently known (apo S)AA-proteins. Additionally, the pedigree analysis of affected cats su ggests a familial trait. (C) Elsevier Science B.V.