An excessive thirst, or an increase in urination, are symptoms of many serious medical problems, but are frequently overlooked as they are simply thought to be due to hot weather or dry food etc.
More often than not you may not specifically notice an increase, but rather a change in habits such as drinking from the pool or a basin, or asking to go out at night. It can be very useful to get used to noticing how much water your dog or cat drinks, as well as their normal frequency of urination. This will enable you to notice changes early and have them investigated. Early detection is critical for many of the possible causes.
Your pet may not seem unwell, and the only symptom of their illness may be the increased thirst or urination. A very common cause is diabetes. Classically diabetes causes increased thirst and urination, as well as losing weight despite having a very good appetite. But not all diabetic pets present with these symptoms, or their onset may be gradual and so symptoms may pass unnoticed.
Diabetes is a very treatable condition, but the longer it is left, the harder and more expensive it may be to treat. Another common cause of an increased thirst is kidney failure. There are many triggers for kidney failure in animals, but in many cases we cannot identify the specific cause. Frequently it is simply an age related organ failure, especially in cats. Whilst it cannot be cured, the earlier kidney failure is detected, the greater the chance that its' progression can be slowed and affected pets can continue to have a good quality of life. Liver problems are another cause of increased thirst and urination that is due to an organ failing to function
Other diseases with similar symptoms include hormonal conditions such as Cushings disease and an overactive thyroid gland, a common condition in elderly cats. Hypercalcaemia, an elevated level of calcium in the bloodstream, also causes excessive thirst and urination and has many causes itself, including several types of cancer.
Since the symptoms of most of these conditions are so similar, it is necessary for your vet to conduct a thorough clinical exam to make a diagnosis. Blood and urine tests will usually be needed as part of this exam and some pets may require further tests such as x-rays. An increased thirst is defined as an animal drinking more than 100ml per kg body weight per 24hrs. For example, a 20kg dog drinking more than two litres of water a day. So if you are concerned that your dog or cat may have an increased thirst, or be urinating more, make an appointment to see your vet as soon as possible. There is most likely a real reason for them drinking more, it's probably not just the hot weather!