Julie has three dogs. While she adores them all, she calls Oscar her “heart” dog: there’s something special about him. He has an outstanding personality, making friends everywhere he goes. When he’s out, he’s friendly to any people or dogs that he encounters. Julie says he’s a kind, loving dog who has “soul in his eyes”. Anyone who’s been lucky enough to have a “heart” dog will know what she means when she describes this.
Oscar even enjoys a small amount of fame: Julie is a classical pianist, active on Instagram as “9to5pianist”, presenting one minute video demonstrations of her highly accomplished piano playing. Oscar can often be seen in the background, sometimes sleeping, and other times actively listening to the music. He often attracts online comments from people watching the videos.
Oscar has had his fair share of health issues over the years; the main problem has been arthritis linked to rupture of his cruciate ligaments. He’s been on a special high fish oil diet to improve his joint health, and this has made a big difference. He’s able to enjoys active, long walks, and in many ways, he still behaves like a young dog even though technically, at fourteen years of age, he’s now officially an “older dog”.
A few weeks ago, for no obvious reason, Oscar began to drink more water than usual. Like most dogs, he had always had regular eating and drinking habits. He has always eaten a small bowl of food twice daily, and drank up to a quarter of a bowl of water with each meal. In mid-March, Julie noticed that he was finishing the bowl of water, licking it dry, and even drinking a bit more when she filled it up.
At first she thought this might just be a short term thirst, perhaps due to drinking some sea water on a walk or some other temporary reason. But after two weeks, his thirst continued to be at this new, higher level, so she brought him to see me to find out the reason.
Increased thirst is known as “polydipsia” in the veterinary world, and Julie was right to bring Oscar to the vet. While it doesn’t cause any harm in itself, a big thirst is a sign that the body’s metabolism is malfunctioning.
It’s important to discover the underlying problem so that this can be treated before other signs of ill health start to develop.
The first stage of investigating a thirsty animal is to carry out a careful physical examination. Sometimes there are external clues about an underlying illness, such as yellow gums (jaundice), pale gums (anaemia), abdominal swellings (tumours) as well as many other possibilities. The good news for Oscar was that there were no such abnormalities: he appeared to be in fine physical health. Julie had brought him to me early enough so that whatever was causing his increased thirst had not yet started to cause other signs of illness.
The second stage of searching for the reason for increased thirst is to carry out “in-house” laboratory tests. I collected samples of urine and blood from Oscar, and analysed them to discover the basic facts of his internal metabolism. There were two aspects to this.
First, I measured a panel of seventeen enzymes and chemicals in his bloodstream. The good news was that most of these tests came back as normal: Oscar did not have diabetes (the most common cause of a huge thirst) and he was not suffering from kidney disease. However two of his liver enzymes were elevated above the normal range: this was the first clue in the search for the cause of his problem.
Secondly, I carried out simple analysis of a urine sample. This showed that his urine was far too dilute, and there was some evidence of a urinary tract infection.
So putting the results together, what was going on with Oscar and how could I help him?
The combination of laboratory results initially pointed towards Cushing’s Disease (also known as “hyperadrenocorticism”).This is caused by a benign tumour that causes the adrenal gland to produce high quantities of cortisone, a hormone which has multiple effects around the body, including inducing a dramatic thirst. Treatment is simple, with daily tablets to reduce cortisone production, but the diagnosis needs to be confirmed with an extra test that can only be carried out by a specialised veterinary laboratory.
I took a couple of extra blood samples from Oscar to send off to this laboratory, and a day later, the result came in: disappointingly, it was normal. This is where things get complicated: in 15-50% of dogs that have this illness, this particular test can come back as normal. That means that other, more sensitive tests have to be done to double-check for this common hormonal illness.
Oscar is coming back into our clinic tomorrow for this next series of blood tests to be carried out. With luck, these will confirm the suspected diagnosis of Cushings Disease. But in the world of health and disease, nothing is guaranteed.
Could Oscar have some other underlying cause of his huge thirst? The next series of tests should give helpful answers. Watch this space and I will let you know when we finally solve the mystery of the big thirst of this friendly little dog.