Personality Change in Older Dog

Similar to a Human’s Alzheimer’s Dogs can have Cognitive Dysfunction Syndrome

I have an older Lab cross that has undergone extreme personality changes. He is withdrawn, does not want to be around us and refuses to come indoors at night. Is this condition treatable? Toby’s regular vet thinks he is in pain due to severe arthritis but, he is not sure what is going on.

Dr. Nichol:
Your veterinarian is probably right about the joint pain. Degenerative arthritis affects a whole lot of dogs as well as cats of retirement age. Big kids like your Lab mix are especially hard hit. That continuous dull ache can make it hard to get up and walk. But I agree with you that your boy’s personality change may have another cause.

An aging brain disorder called cognitive dysfunction syndrome is responsible for most of the befuddled and sometimes erratic behaviors of aging dogs. Known as CDS, it’s nearly identical to Alzheimer’s of middle-aged and older people. It is so similar that dogs with senility have become a research model for the study of this debilitating human disease. It’s a big problem. The loss of healthy mental function steadily drains the life out of anybody’s last good years.

Cognitive dysfunction syndrome is common in dogs. About 28% aged 11 – 12 years and 68% of those over 15 are losing control of their mental and physical functions. Symptoms include confusion and reduced interest in play and exercise. Some affected dogs become irritable or develop hyperactive, repetitive behaviors; others may turn apathetic and act depressed. Sleeping more during the day or restlessness at night are also common signs. A great many no longer follow simple directions. Like your dog they become disconnected from those who love them. It’s common for them to forget their house training and begin to urinate or defecate indoors.

There are treatments for cognitive dysfunction that can make a difference. I invite you to visit my website,, to learn more. Click on the Pet Behavior tab and then click Older Dogs.