Behavior Changes in Cats

Cats tend to act out of the ordinary when they're ill or stressed.
i Hemera Technologies/ Images

Cats are notoriously fickle in their emotions, and Miss Kitty can switch from purring lap-cat to hissing, claws-bared tigress in the blink of an eye. These whiplash-inducing mood changes come with cat ownership, but if your kitty's behavior changes dramatically and permanently, an underlying issue could be causing it.


Mother Nature and Father Time are the ultimate tag-team, and together they cause some unpleasant changes in your cat as she ages. Older cats aren't as agile or spry as they were in their younger days, and without that boundless energy they tend to spend their days resting instead of running around like liquid lightning. Cats can also develop medical issues as they age, such as hyperthyroidism and diabetes, that can alter their usual behavior. As with many humans, cats can have less patience for the antics of their housemates as they grow older, causing your once easy-going kitty to grumble and complain if bothered.

Medical Issues

No one is at their best when sick or in pain, as anyone who's had to deal with the Man Cold can attest. Your cat can't tell you when her tummy hurts or is otherwise feeling under the weather, but her behavior will betray her less-than-optimal health. Sudden aggression, peeing outside the litter box and other changes in normal behavior could indicate an underlying medical condition. Appetite changes, weight changes and changes in litter-box use can point to conditions such as diabetes, hyperthyroidism or kidney problems. See your veterinarian for a complete checkup and treatment plan to help your kitty heal.

Stress and Fear

Even though your cat tries to portray herself as a smooth, indifferent gal who only takes a casual interest in the goings on of the household, the truth is that stress and fear can affect her more than she lets on. Changes in routine or dynamics within the household can create stress, and your otherwise calm kitty may start to act out to relieve this anxiety. She may seem more aggressive or spend more time hiding under your bed than usual. Grooming is a stress reliever for cats, and she may take this activity to a new, unhealthy level and actually start licking herself bald in her attempts to calm herself.


Just as there is no one reason for your cat's behavior change, there is no single solution that will change it back. Make note of the behavior changes as soon as you notice them and visit your veterinarian to have her tested for medical issues that may be the underlying cause. In most cases, once the medical condition is under control your cat's behavior returns to normal. For changes due to stress, calming pheromones dispensed by a plug-in diffuser can help promote relaxation in your kitty and reduce the unwanted behavior.

Always check with your veterinarian before changing your pet’s diet, medication, or physical activity routines. This information is not a substitute for a vet’s opinion.

the nest