Whilst little has been written on the effects of canine hypothyroidism on behaviour, it is
accepted that behaviours can be altered in human patients suffering from this condition. Investigations indicate that psychological
abnormalities such as mood swings, depression, irritability and aggression can be present in hypothyroid patients. It has
been stated that all too often thyroid disease will manifest itself through nothing but behavioural symptoms and that unless
the physical requirements for thyroid hormones are satisfied, psychiatric techniques will not help. In addition it has been
observed in humans that once an organic diagnosis is made and treated there is an immediate disappearance of all neurotic
Even mild or moderate stress can tilt the delicate balance of the low thyroid person and
cause acute anxiety or depression.We now know that similar responses may occur in dogs suffering from an under active thyroid
gland and that often a change in behaviour can be one of the first signs of this disease. In many cases this may be observed
before one sees the more commonly recognised symptoms such as lethargy, weight gain & hairloss.
The changes in behaviour can include any of the following: - Dog to dog aggression (fight),
Dog to dog aggression (flight), Dog to human aggression (fight), Dog to human aggression (flight), Territorial aggression,
Irritability, Mood swings General fearfulness, Separation anxiety, Fear of Thunderstorms, Noise sensitivity,General anxiety,
Shyness, Hyperactivity, Compulsive behaviours and Low concentration span. Suspicion should arise when the happy family
pet’s behaviour changes suddenly, for no apparent reason.
It was originally thought that hypothyroidism
was a disease of middle age but sadly we are seeing it younger and younger dogs.There are a number of reasons why dogs develop
hypothyroidism the most common being autoimmune thyroiditis which accounts for 80% of cases. It is a familial, heritable condition
and therefore affected dogs should not be used for breeding.I wonder how many Cocker Spaniels have been euthanased as a result
of being diagnosed as suffering from “Cocker Rage Syndrome”, when a simple blood test may have shown that they
were suffering from HT and the unprovoked aggression exhibited was in fact a symptom of this treatable disease.
So why are we seeing more and
more cases in younger and younger dogs? Remember 80% of the cases of hypothyroidism are due to autoimmune thyroiditis and
this treatable disease is only one of many that can occur when the immune system is compromised, by poor diet, some drugs,
exposure to chemicals in the home and the environment in general, and stress created by inadequate or the wrong kind of exercise,
unrealistic expectations of a dog by owner, changes in the domestic situation etc.
Should you suspect that
your dog could be suffering from Hypothyroidism, please consult your vet.
Article written by Sheila Hamilton Andrews MSc CCAB