Aggression in Dogs Can Be Due to a Medical Condition

If you look through news articles from around the country, you'll find at least one incident of a dog attack nearly every day. Usually more. Then you'll read comments from people saying we should ban certain breeds because of their aggression.

But behind every aggressive act by a dog there is a reason. There is no one breed that is more dangerous than another. It depends on how they are raised, how well they are socialized during the first few important weeks of their lives, whether or not they are kept on a chain, how much training they have and how healthy they are.

Dog owners don't always consider it, but a medical problem can be the cause of an otherwise docile dog becoming aggressive. Here are a few possible causes or contributors to a dog's aggression:

1. Hypothyroidism - A condition in which the thyroid gland doesn't produce as much thyroid hormone as is needed. Some signs of this problem could be weight gain, loss of hair and lethargy. Running a blood test can determine the level of thyroid hormone and whether or not treatment is needed in the form of medication.

Hypothyroidism is not an all or nothing condition, though. There are various degrees of this problem. A dog may only exhibit one or 2 of the signs and be in the 25 percentile range of normal, whereas a healthy dog would be in the 50 to 100 percentile range. This is still low enough to need treatment and can be a potential cause of aggression that does not seem to have an obvious reason behind it or seems to be excessive for the circumstances. Raising the thyroid hormone level by giving synthetic thyroid hormone can cause a dramatic improvement.

2. Neurological problems - If a dog is born with or develops a neurological problem due to head trauma, for instance, this can cause the dog to see the world differently than a normal dog. This can bring on inappropriate behavior and aggression due to fear or the need to self-protect. Some of the neurological problems include:

a. Hydrocephalus - a condition in which the spaces in the brain that are filled with fluid become enlarged and the surrounding brain tissue becomes thinned and compressed. This is most common in toy and short-nosed breeds. There may not be any clinical signs in mild cases, but in the more pronounced cases aggression may be a sign that something is going on in the brain. This can be diagnosed by a CT (computed tomography) or an MRI (magnetic resonance imaging).

b. Encephalitis - This can be bacterial or viral. Any condition where there is inflammation of the brain can cause symptoms such as aggression.

c. Head trauma - When the brain is traumatized, swelling and bleeding can effect the functioning of the brain in that region. Aggression can be a result.

d. Brain tumors - When an elderly dog suddenly shows signs of aggression for no obvious reason, the possibility of a brain tumor should be explored. This can be diagnosed by the use of a CT or MRI.

3. Behavioral seizures - Partial seizures in an area of the brain that controls aggression can cause sudden unprovoked aggressive attacks. The specific breeds that are known for this sudden, sometimes violent behavior are the Springer spaniel, bull terrier, Chesapeake Bay Retriever, cocker spaniel, golden retriever, and poodle.

The clinical signs for this type of seizure-related aggression are different than any other type of aggression. They include:

a. A change of mood just before the seizure

b. Sudden aggression, usually violent, for no obvious reason

c. Aggressive body language or posturing, which can last throughout the seizure attack, which could be minutes, hours or even days.

d. Signs of involuntary discharge of the salivary glands and anal glands and dilated pupils.

An EEG (electroencephalogram) will often show if there are abnormalities.

So if you or someone you know has a dog that has suddenly become aggressive for no apparent reason, have it checked out by a veterinarian. There might just be a very real medical condition causing the problem and with treatment and medication, the aggressive behavior could completely disappear.