Medical and Behavioral Causes for Canine Aggression

By Ruthie Bently

Have you ever been growled at or bitten by a dog that as a rule is a calm, even-tempered animal? I have, and it was because I made a mistake. I had given my dog a bone and he kept trying to take it into the bedroom to chew it in his favorite place: my bed. I kept taking the bone into the kitchen and placing it on his rug where he was allowed to chew it. That just didn’t suit him.

I got bit when I approached him from behind and reached around him to take the bone away. The proper way to remedy the situation would have been to put him on a sit/stay, pick up his bone while facing him and crate him with his bone, so he could enjoy it in peace and my quilt wouldn’t get dirty. In his defense it was the first beef bone he’d ever been given and he was two years old. He had no idea who was behind him; he didn’t have eyes in the back of his head and was protecting his property. This aggression was caused by a behavior I was able to correct with patience, understanding, love and CANIDAE Snap Biscuit treats.

Behavioral causes for canine aggression can include protection of their persons, perceived property or other four-legged companions. Some dogs will show this aggression when being walked by their owners. They are walking happily down the sidewalk when all of a sudden there is a barking, snarling mass of fur at the end of a leash. If you are walking with or without your dog in the other direction, I suggest crossing the street before continuing on your walk.

A dog does not necessarily see property lines in the same manner that humans do. It doesn’t matter if they are behind or in front of a fence – in some dogs’ minds the property ends with their line of sight. If you have ever parked in a parking lot and been accosted by a dog in the car next to you showing teeth and/or growling, it may be because the dog sees you as a threat to the car they are in. They don’t know that you could care less; they were left there by the alpha family member and are doing their job.

Fear can cause aggression. A dog may be afraid of thunder, fireworks or other loud noises. They may be fearful of noises made during the normal running of appliances that they may not be used to (i.e., the dishwasher, clothes washer or dryer). A dog may be afraid of another dog, and may show aggression to make himself look more threatening to a dog that is approaching them with body language they don’t like.

Dominance can also cause aggression. Dogs may fight over territory, a female they both covet, food or even a family member. Jealousy can also cause dominance aggression. I had a client with a male Akita, and she began dating several years after she became a widow. The Akita did not like the new man in her life and made his feelings known. By involving her new beau in the dog’s day-to-day schedule which included feeding, walking and training, the problem was resolved and they became a happy family.

Canine aggression can also be caused by medical problems. One report mentioned over fifty different medical reasons for canine aggression. Hypothyroidism is one of the most common and occurs when there is too little thyroid in a dog’s system. Your vet can perform a test for hypothyroidism and may prescribe thyroid medication to remedy the situation. Hypothyroidism currently affects more than fifty dog breeds. Hypoglycemia, which is low blood sugar, is another cause and may or may not be linked to canine diabetes.

A trauma caused by a blow to a dog’s head or a brain tumor, which can cause swelling, bleeding or injury to the brain, can result in canine aggression. Dogs can contract either viral or bacterial encephalitis. Rabies and distemper are both forms of viral encephalitis. Some studies show that dogs can contract distemper from a distemper vaccination. The lack of serotonin in a dog’s brain can cause them to become aggressive, as it is the neurochemical control for aggression. Epilepsy, which has many causes, has also been noted as a form of canine aggression. Cognitive Dysfunction Syndrome associated with aging canine seniors can also cause canine aggression.

Canine aggression can be due to either a behavioral or medical cause. If you have a regularly well-behaved dog that begins behaving oddly for no apparent reason, it is time to visit the vet for a checkup.

Read more articles by Ruthie Bently