Common Causes of Cats' Behavior Changes

The cats behavior is often unpredictable and it may often change. However, there are some behavior changes that can indicate a health problem or that something is going on with your cat. Some of the most common causes of cats’ behavior changes include aging, stress, the mating season, pregnancy or a medical condition.


As a cat gets older, he will change his behavioral pattern. He may be sleeping more, have a more sedentary lifestyle and will spend more time indoors and around his owners, seeking more attention from the family members. This change in behavior is natural in senior cats as they will have a lower energy level. However, your cat may also change his behavior due to pain. If your cat becomes aggressive, this may be due to an undetected medical condition, so you should visit the vet to identify the problem.

After Neutering

After neutering, your cat will also change his behavior. He will be less active, sleep more and seek more attention. This is due to the fact that he is no longer interested in mating and redirects his energy towards other activities.

Mating Season

During the mating season, cats that are not neutered can change their behavior; your cat may be more aggressive and more vocal than usual.

You will also notice that your cat spends more time outdoors looking for a cat to mate.


A female cat will change her behavior during the period of a pregnancy. She may be hiding, looking for quiet and warm places; she will also be more affectionate and less aggressive.

The signs of pregnancy can be detected as early as 3 weeks after the fertilization. The nipples will change in color and will become larger. By week 5 you may also notice that the cat’s abdomen is larger.


An illness may cause sudden behavior changes in your cat. The pain may make your cat more aggressive. The cat will also hide and may paw or lick the affected areas. The cat may also be less active and lethargic.

The medical problems may range from dental diseases to urinary infections. Try to see what other symptoms your cat displays and consult the vet.


Stress may cause behavior changes. The stress may originate in different changes in the cat’s environment such as moving house, a new family member or a new pet.

Identifying the cause of stress is important to find the most suitable treatment. There are a few natural remedies, but in more severe cases, medication treatment is necessary.


If your cat has an injury acquired during playing or fighting with other felines, this may cause a change in his behavior, due to the pain. Groom your pet on a regular basis and see if there are any injuries that need attention and treatment.

Other causes of temporary behavior change may include defensiveness and the guarding of the personal space. However, the cat will become aggressive only for a short period of time. You should be alarmed when your cat displays a change in behavior that lasts for several days or weeks.