Abnormal behavior and loss of ability to perform daily routines in absence of physical pathology could be related with physiopathological changes relationed with the ageing process.

In this work, clinical signs indicatives of cognitive deterioration in a group of feline patients are described. A list with all the possible clinical signs that could be present in a confusional state was made. They were grouped according to behavior patterns and involved cognitive abilities.

Through a systematic behavioral exam and using the mentioned list as reference, five castrated Siamese cats (1 male and 4 females) older than 12 years old were evaluated. Previously a complete clinical exam including neurologic, cardiovascular and laboratory tests (hematology and blood chemistry) was made.

The number of patients for each behavior and altered ability was: Disorientation: Less recognition of people: 1, Less recognition of animals: 2, Less recognition of places: 3, Less ability to face daily routines: 4. Changes in the sleep/wake cycle: Inversion of cycle:1, Hypersomnia: 2. Loss of learning and memory: Loss of learned responses: 1, Unable to learn: 2. Changes in the house soiling: Inappropriate defecation: 1, Spraying: 2, Incontinence: 3. Changes in social interaction: Lower interaction with owners: 1, Hyper attachment to their owners: 2, Lower interaction with other cats: 3. Changes in mood and mental alert: Decreases in responsiveness to environmental stimuli: 1, Increase in vocalization: 2, Slowness to respond to requests or commands:3, Decreases in activity: 5, Irritative aggression: 5. Changes in exploratory behavior: Stereotypes: 1, Substitutional activities: 2, Scratching: 3. Changes in the feeding behavior: Hiporexia: 1, Polyphagia: 2, Selective appetite: 3. Changes in self- cleaning: Increases: 1, Decreases: 2.

An objective definition of clinical signs that more frequently characterizes the confusional syndrome will allow to find a standarized diagnosis criteria for early detection and treatment of cognitive dysfunction improving the quality of life.