Suspected zinc-induced copper deficiency in growing kittens exposed to galvanised iron

AIM: To investigate the possible causes of fading coat colour and an acquir ed hind-limb ataxia affecting sixteen 4- to 5-month-old kittens in a dosed feline colony during 1993 and 1994. METHODS: Records of kittens and litters born in the colony between 1991 and 1997 were analysed. The kittens had been kept from birth until approximate ly 5 months of age in plastic cages with galvanised iron bar doors. Histopa thological sections from 4 of the worst affected ataxic kittens necropsied in 1993 were re-examined. In addition, 6 of the original 16 affected kitten s that survived were re-examined as 4- to 5-year-old adults, which were mod erately ataxic; these cats were then humanely killed for necropsy. RESULTS: In the kittens, clinical signs included lordosis, dysmetria, ataxi a of the hind-limbs and fading coat colour; histopathological lesions inclu ded Wallerian-type degeneration in the spinal cord, pens and medulla, and n euronal degeneration in the vestibular nuclei and ventral horns of the spin al cord. Analysis of colony data ruled out an inherited disease, and there was no evidence of dietary inadequacy or excess. Similar, though milder, cl inical and histopathological changes were noted in the affected adults. CONCLUSIONS: Circumstantial evidence is consistent with a diagnosis of zinc -induced copper deficiency caused by the ingestion of zinc oxide from the g alvanised iron bar doors. CLINICAL RELEVANCE: Because of the possibility of zinc-induced copper defic iency galvanised iron should be avoided when designing and constructing cag es for cats in veterinary clinics, pet shops and boarding facilities.