Dog Aggression & Hypothyroidism
The information listed below is intended to help dog owners but is not intended to replace the advice, counsel, or assistance of licensed personnel. It is always recommended that you seek the help of your veterinarian.
When a dog starts showing aggressive or reactive behaviors it is important to rule out any medical causes of this behavior. One of the most overlooked medical conditions is hypothyroidism. Different dogs may exhibit different clinical symptoms such as unexplained weight gain, hair loss, or skin/ear infections. Typical behaviors are incessant whining, nervousness, anxiety, fears & phobias, disorientation, hyperventilating, lethargy, depression, and irritability. Some dogs show siezure-like disorders. After an episode, most dogs will behave as though they were coming out of a trance like state, unaware of their previous behavior. The ONLY way to really know if your dog has hypothyroidism is to run a full Thyroid Antibody Panel (Thyroid 5™). A simple T4 test will not be sufficient as it is rarely useful when behavior problems are involved.
Labs vary in quality and experience, and it is recommended to have Dr. Jean Dodds, the foremost authority on Canine Hypothyroidism, located at “Hemopet” in Orange County California, run the tests. In order to have Dr. Dodds run your dog's Thyroid Antibody Panel, you need to visit Hemopet.org
and print out both testing forms to bring to your Veterinarians office. Call your Vet first and explain that you would like Dr. Dodds to run these tests, but that you would like them to do the blood draw and send the sample to her at Hemopet. Most Veterinary offices are happy to do this for you, it not, find another Vet.
Ask your Vet for a copy of the results so you can analyze the results. It is very important to do this, as most Vets will read the test, and as long as the dog's results fall anywhere in between the laboratory's "Normal Range" they will tell you (and believe) that the dog is not hypothyroid. Borderline hypothyroidism is a condition where the dog is definitely suffering from a weakened thyroid system, but it is not yet severe enough to register out of the "Normal Range". Just because it has not reached an extreme state yet, does not mean that it is not affecting your dog's health and behavior negatively.
To analyze your dogs test results, the first thing you will need to do is calculate the 50% mark of the "Normal Range" for each panel. To calculate the 50% point, you add the end values of the range and divide by 2.
T3 Lab "Normal Range" = 45 - 150
So, 45+150 = 195, 195/2 = (97.5) = 50% of the "Normal Range"
Therefore, if your dog's T3 level was less than 97.5 in this instance, he would be below 50% of the range. You need to do this calculation and comparison of these percentages with each of your dog's test results.
Here is an example of Fido's results before Thyroid supplementation.
Lab Range T3 = 45-150
Lab Range T4 = 1.0-4.0
Lab Range Free T3 = 3.0-8.0
Lab Range Free T4 = .65-3.0
Lab Range T3 Antibodies = <2.0
Lab Range T4 Antibodies = <2.0
50% of Range = 97.5
50% of Range = 2.5
50% of Range = 5.5
50% of Range = 1.825
Fido's T3 = 76
Fido's T4 = 2.44
Fido's Free T3 = 3.1
Fido's Free T4 = 1.14
Fido's Antibodies = 1.2
Fido's Antibodies = 1.0
Fido's behavior can definitely be negatively affected by his Thyroid status.
If your dog falls below the 50% mark of these ranges, you should speak to your Vet about supplementing your dog on a thyroid supplement. Once your dog is on the right amount of medication (you will need to do regular follow-up testing throughout your dog's life) you may see big changes in his behavior, or may at least see "the edge" taken off.