Interpreting a Dog Personality Change

A dog’s personality should be invariable throughout his entire life. However, there are some cases when a dog will suffer from personality changes. These may be due to the mating season, neutering procedure, aging, medical conditions or anxiety and stress.

Dog Diseases

A sudden change of personality may be indicative of an undetected medical condition. Monitor your dog for additional symptoms and visit the vet for a proper diagnosis. The dog may be suffering from a light infection, but he could also have a tumor.

After Neutering

After a dog has been neutered, you may notice some personality changes, which are normal. Your dog will be much calmer and less active, but he will keep his basic personality traits. If he’s a happy dog, he will be the same. If he’s independent, you will still notice this trait. If you notice that your dog’s personality changes from one extreme to the other, you should consult your vet, as this may be caused by an undetected medical condition.

Mating Season

Your dog’s behavior will be significantly changed during the mating season. When female dogs come into season, they experience a lot of hormonal fluctuations. The female dog comes into season for the first time at the age of 6 to 12 months. There are some breeds that mature at 12 to 16 months. During the heat cycle, the female dog may have sudden personality changes and can be aggressive at times.

On the other hand, male dogs will have the urge to mate and they will become very agitated and even aggressive.

Pregnancy Symptoms

If your dog is not neutered and has a sudden change in her behavior, she may be pregnant. Pregnant dogs may be more agitated in the first stages of pregnancy, and become less active after the first 3 weeks of pregnancy. Consult the vet to confirm the pregnancy or see if the personality change is not linked to a different reason.

Dog Aging

As your dog gets older, he will change his behavior. His personality may also suffer from changes. Typically, a dog is considered senior starting from the age of 7 to 8. However, some giant breeds can become senior as early as the age of 5. Other symptoms of aging will include slower movement, more sleep and your dog will be less energetic.


A depressed dog may become suddenly inactive and lack his normal joyfulness. Depression can be caused by a disease or the loss of a companion. Medication is available and you should also try to comfort your dog to help him overcome depression.

Anxiety and Stress

Anxiety and stress can also contribute to the change of your dog’s personality. Changes in the daily routine or food, moving to a new house or changing owners can all contribute to a dog being stressed.

A sudden personality change may be normal for aging dogs and during the mating season, but if you rule out these causes, you should visit the vet, as your dog may have a health problem.