Data collected provide estimates of the prevalence of various degrees of age-related behavioral changes associated with cognitive dysfunction in dogs. Age-related behavioral changes may be useful indicators for medical intervention for dogs with signs of cognitive impairment.

Results suggest that male cats and cats from multicat households are more likely to exhibit urine marking behavior than females and cats from single-cat households. Results also suggest that attention to environmental and litter box hygiene can reduce marking frequency in cats, regardless of sex or household status of the cats, and may come close to resolving the marking problem in some cats.

Administration of fluoxetine hydrochloride for treatment of urine spraying in cats can be expected to considerably reduce the rate of urine marking. The frequency of spraying before treatment is predictive of the spraying rate when the drug is discontinued.

Age-related behavioral changes in dogs are progressive. Clinicians should consider trying to predict which dogs are most likely to become progressively impaired during the subsequent 6 to 18 months.

Clomipramine and fluoxetine were equivalent in treating urine marking. Longer treatment increased efficacy. Most cats return to marking after abrupt drug withdrawal. A second course of treatment can be expected to be as effective as the first.