The Interaction of Illness and Behavior

(Originally written for DogWatch, a newsletter for the general public from the Cornell University College of Veterinary Medicine)

When my sister’s puppy Zeke was about 10 weeks old, he got some kind of infection and had to stay at the veterinarian’s for over a week. By the time he had completely recovered, his personality had changed from very happy and cuddly to suspicious and snappy. My sister says that the illness did it, but I never heard of such a thing. Are there some infections that can change a dog’s personality like this?

When we think of medical problems that may negatively affect behavior, we typically think of those which either affect the brain or cause pain. In the former case, a tumor in certain areas of the brain may cause personality changes. Pain from infection in any part of the body may cause a normally happy, gregarious pet to retreat and react irritably when disturbed. In both of these cases though, following treatment and recovery the animal’s behavior returns to normal.

The one exception to this takes the form of illness or injury that occurs in young puppies. In a survey conducted by James Serpell and J. A. Jagoe,  out  a population of 551 dogs 73 ( or 13%)   experienced illness between birth and 16 weeks of age and these animals showed more aggression, fear of strangers and children, and separation-related barking. In other words, the negative behavioral changes associated with early illness appear very similar to those associated with restricted or inadequate early socialization.

But wouldn’t a sick young animal naturally get more attention and exposure to novel people and experiences and thus become more rather than less socialized by the event? Although the study didn’t delve into the specific nature of each pup’s experiences, studies of the behavioral effects of illness in human youngsters suggests that the behavior of medical staff and other significant people in the young individual’s life may play a role in this problem. For example the hearts of many veterinarians and their staffs often naturally go out to sick young animals and they consciously or subconsciously lavish extra attention on these animals. Even if they don’t, concerned owners surely will do this.

Sadly the more frightened and miserable sick or injured animals appear, the greater the temptation to baby them. But for as caring as such human responses superficially may appear, they may result in highly dependent animals who only feels comfortable with those few people. If follow-up visits to the veterinary clinic occur and owners project their own fears regarding these onto their puppies, the animal may feel obligated to assume a defensive stance and growl, snap, and/or otherwise resist handling and treatment.

Further complicating matters, people whose pets experience serious illness often remain over-protective and over-indulgent even after the animal becomes well. If Zeke fully recovers from his illness  but his owner refuses to allow him to play with other dogs and children for fear he might pick up another infection or injure himself, this additional lack of quality interactions with others  will make him even more fearful. Similarly if owners delay enrolling a pup in puppy class for the same reason, or dismiss the animal’s growling at them or a neighbor saying, “It’s understandable after all the poor little guy’s been through,” this human response to the pup’s illness may undermine the animal’s behavior far more than any illness.

So how can we avoid these negative illness-related side-effects? First, remember what Hippocrates said: Faith in the patient’s ability to heal himself is paramount in the treatment process. For pet owners that means having faith in the wonderful healing capacity of your pet’s body too. Armed with this awareness, communicate with your sick pet in a manner that instills confidence rather than dependency. Avoid baby-talk and those higher pitched tones we know communicate submission. Three, don’t excuse negative behavior; humanely deal with it. The majority of such behaviors results from fear and accepting it merely makes the fearful pet more so. And finally,  no matter what the outcome of the illness, treat the animal as normal to help your pet accept any limits quickly and confidently.

Illness happens. But with an awareness of how our own and others’ responses during these times may affect animal behavior, we can ensure our pets the smoothest mental as well as physical recovery.