Summer 2002

How Do You Know If Your Pet Is Excessively Thirsty ?

Many owners assume that excessive thirst, or polydipsia, is normal and means that their pet is fine. There are times when animals need to drink a lot to replenish their body water, like if they have been for a long walk, or it is a very hot day, but consistently drinking excessively for days or weeks is usually abnormal.

In older cats, the most common reason for polydipsia is chronic kidney disease. Old cats have a tendency for scarring to occur in their kidneys, which reduces the amount of wastes the kidney can filter into the urine. This may lead to a build up of wastes in the blood, and an early response to this is for the cat to drink excessively. Generally cats begin drinking excessively many months, perhaps even years, before they may get really sick from kidney failure. If you notice your puss heading to the water bowl more often, we can check their blood and urine to see if their kidneys appear to be working well.

An infection in the kidneys is a quite rare, but also can cause polydipsia in both cats and dogs. Usually these animals are suddenly very sick, with a fever, and they stop eating. This problem may be treatable but usually requires time in hospital, antibiotics and being on a drip to fix.

Older dogs who drink excessively may have a condition called Cushing’s disease, where their adrenal glands produce an excessive amount of the steroid hormone cortisol. These dogs tend to be ravenously hungry, and often have a pot-bellied appearance. We need to check blood and perhaps ultrasound the dog to diagnose this condition, and it can be managed well with medicine most of the time.

Any dog or cat with a fever may drink excessively. Also, animals that eat a lot of dry food will drink more than those that at tinned food. Finally, diabetes in dogs and cats will also lead to excessive drinking, eating and weight loss. This is detected by looking at the blood sugar levels. There are other, rarer conditions that will also cause polydipsia.

How much drinking is too much drinking? A general rule is that cats who drink more than 45mls/kg per day and dogs that drink more than 90ml/kg per day have polydipsia. Thirsty animals often drink from unusual places, like the pond, toilet bowl or shower cubicle too. If you think your animal is drinking a lot, a check up is in order.