The sick dog with a tragic facial expression
When Mrs Sayers called me last week, I wasn’t surprised to hear that Tyson, her ten year old Boxer, was slowing up and had gone off his food. The weather had been hot, he was getting older, and he was a lazy dog in any case. Most dogs of his type will have been taking things easy in recent times. However, after talking to her, I decided that it would be safest for me to examine her dog. She explained that his personality had been quietening down since Christmas, and as well as slowing up, he had been gaining weight. She had just weighed him in the local pet shop: he had put on 7kg in the previous six months: that’s over a stone. And she had definitely not been giving him any more food. It was obvious that this was a bit more than “slowing down in warm weather”. She made an appointment to bring him down to see me.
When I examined Tyson, apart from being distinctly overweight, there were a few other signs of illness that worried me. He had patches of bald skin over his back, one on each side over his tail head. The balding areas of skin had turned a black, deeply pigmented colour, a phenomenon known as “hyperpigmentation”. And his skin was cold to touch, which seemed especially odd on a hot day.
Finally, when I listened to his chest with my stethoscope, Tyson had a slow heart rate, at just about sixty beats a minute.
A Boxer of his type would normally have a heart rate about twice as fast as this.
There was one more aspect of Tyson that was worth commenting on, but it is hard to put your finger on this one: he had “a tragic expression on the face”. I placed that in quotation marks because this is a phrase straight from the text books: dogs suffering from a particular condition are said to look like this.
What is the condition? It’s a common hormonal disease of older large breed dogs, known as hypothyroidism, or an under active thyroid gland.
This is a condition where the thyroid gland in the neck becomes atrophied. The gland stops producing the necessary quantities of thyroid hormones. These are the chemicals that are like the accelerator pedal in a car. Thyroid hormones give dogs energy and zest for life. When they are not produced in adequate amounts, affected dogs become slow and weary. Some dogs show only minor signs that can be not easy to assess. Rarely, a dog may show a wide range of typical signs that seem to shout out the diagnosis. Tyson definitely fell into this category.
A blood test is needed to confirm hypothyroidism, so I took samples from him to send off to the laboratory.
The laboratory measures two hormones to confirm the diagnosis. The “Total T4” is a measurement of the amount of thyroid hormone in the blood stream. This is the equivalent of taking a sample of petrol-laden air from the cylinder of a car, and measuring the exact concentration of petrol fumes. If the accelerator is pressed to the floor, there is a high level of petrol, and if the car is idling at a standstill, there is a low level. When the results came in, his Total T4 levels were less than a fifth of the normal level. To make the car analogy again, his engine was sputtering and about to stall.
To be doubly sure of the diagnosis, a second hormone is measured, known as “TSH”, a separate hormone produced by the brain. Many dogs with hypothyroidism have high levels of TSH, reflecting the fact that the brain is doing its best to tell the under-active thyroid gland to produce as much thyroid hormone as possible. In Tyson’s case, the TSH levels were over five times higher than a normal dog.
The blood tests had completely confirmed my consulting room suspicions. Tyson was a textbook case of hypothyroidism.
The good news is that hypothyroidism responds very well to treatment. Tyson has already started on a daily hormone supplement tablet, and I am almost certain that he will return to normal within a few weeks.
Mrs Sayers is going to notice three things.
She noticed the first change within two days of starting the tablets: his energy levels picked up. “It’s still roasting hot outside”, she told me, “but Tyson is already running around as if he was a young dog”.
The second change will be weight loss: up until he had this illness, Tyson had always been a fit, slim dog. And just as he had gained weight over six months, he will definitely be back to his normal weight over the same time period. The weight gain was simply down to a hormone abnormality: once that is fixed, he will rapidly become lean again.
The third, and slowest, change will be the regrowth of hair. Baldness, or alopecia, is strongly linked to the hormones in the blood stream, but the hair growth cycle is slow. It will take many months for new hair to grow into the bald areas. But again, there is little doubt that this will happen.
The good news about making a specific diagnosis like hypothyroidism is that the science has been done to prove what is going on. And just as science tells us about the illness, it also informs us about the cure. The signs of Tyson’s illness are caused by the shortage of thyroid hormones: as soon as these hormones were given to him, the problem was completely resolved.