PETSAVERS REVIEW Cognitive dysfunction and the neurobiology of ageing in cats With improvements in nutrition and veterinary medicine the life

Because of improvements in nutrition and veterinary medicine, there are now more elderly cats than ever before. In the USA over the last 10 years, there has been a 15 per cent increase in the number of cats over 10 years of age (Broussard and others 1995), and in the UK it is estimated that there are currently approximately 2 5 million ‘‘senior’’ cats (Gunn-Moore 2003). As this may account for perhaps 30 per cent of the pet cat population (Venn 1992), effective management of these individuals is becoming an ever more important consideration for small animal veterinary practitioners. Unfortunately, accompanying this growing geriatric population there are increasing numbers of cats showing signs of altered behaviour and apparent senility (Fig 1). These behavioural changes may result from many different disorders (Box 1) including systemic illness, organic brain disease, true behavioural problems or cognitive dysfunction. Diagnosis involves a full investigation looking for underlying illness (Box 2). Because cognitive dysfunction syndrome (CDS) is an ante-mortem diagnosis of exclusion, this disorder should be considered once any other illness has been ruled out. The most commonly seen behavioural changes in CDS include spatial or temporal disorientation, altered interaction with the family, changes in sleep-wake cycles, housesoiling with inappropriate urination/ defecation, changes in activity and/or inappropriate vocalisation (see Box 3).