Why Is My Dog Drinking so Much?
Excessive thirst is a very common presenting complaint in veterinary practice, and is something I encourage my clients to watch for with their pets, particularly in old age. As maintenance of normal fluid balance in the body is a very complex process involving several body systems, there are many potential causes.
The key point of this article is that most of these causes are potentially serious, and early diagnosis and intervention by a veterinarian is essential to identify your pet's underlying problem and allow correct and effective treatment.
In my experience, many owners elect to try to limit their pet's water intake in response to their excessive drinking. This is not advisable, as many of these animals have a genuinely increased requirement for water, and restriction will lead to dehydration.
Fluid Balance and Thirst
In the healthy animal, urine production and water consumption are controlled by feedback between the kidneys, pituitary gland and hypothalamus (parts of the brain). There are also stretch sensors within the main blood vessels which can detect if more fluid is required (less stretch equals lower volume of blood equals more fluid needed). In most cases, increased thirst is actually a response to increased urination which would cause dehydration if left unchecked.
The key regulatory mechanism of fluid balance is the renin-angiotensin-aldosterone system (or RAAS). See the video below for a great little tutorial on this topic.
Water intake in excess of 90mL/kg/day for dogs is considered abnormal, but any definite increase in your pet's usual drinking habits is worth investigation, as individual intake will vary depending on many factors such as environmental temperature and the type of diet being fed. You know your pet best- if something strikes youo as being abnormal, then it probably is
Before Visiting the Veterinarian
If your pet is unwell it should be treated as an emergency and your trip to the hospital should not be delayed, however if he/she is bright and eating there are several useful steps you can take to help get to the bottom of your pet's problem. A urine sample is vital in the investigation, so you should attempt to catch a small amount of urine in a clean and dry container. A mid-stream sample is ideal, which means you should allow your pet to pass some urine before slipping the container under them. If your pet is nervous or unsure about allowing you to catch a sample, don't worry, there are several techniques whereby your veterinarian can obtain a sample in the clinic.
Measuring water intake over 24 hours is also useful, though not always practical if there is more than one pet in the household. If your pet is a pedigree it is worthwhile contacting the breeder for information on whether any family members have a history of inherited/congenital illness.
- How to obtain a urine sample from your dog - YouTube
There may be a time when your vet asks you to provide a urine sample from your dog. Dr. Wendy shows how easily you can obtain a urine sample from your dog. T...
This list is not exhaustive, but does cover the most common problems encountered in dogs. Most of these conditions are treatable, particularly if caught early, and many animals with kidney failure for example can enjoy long survival periods with the right combination of a committed owner and dedicated veterinary team.
- Kidney disease
- Urinary tract infection
- Cushing's disease
- Addison's disease
- Womb infection (pyometra)
- Liver failure
- Diabetes insipidus
- Diabetes mellitus
- Drug treatments (especially corticosteroids & diuretics)
- Excess glucose or salt in the diet
- Behavioural (psychogenic polydipsia)
- Secondary to some cancers
It is essential that any animal with excessive thirst is allowed free access to water unless advised otherwise by your veterinary surgeon.
Investigation of increased thirst
Diagnosing the cause of your pet's increased thirst may be relatively straightforward for your veterinarian, or it may involve quite a bit of sleuthing. The reason for this is that investigation of this symptom must be performed sequentially in order to prevent an incorrect or missed diagnosis. Even when there is a high degree of suspicion of one particular disorder, such as is often the case with Cushing's disease, your veterinarian must first rule out heart failure, renal failure, hepatic disease and diabetes. Failing to do this would result in a great many dogs with these other disorders being misdiagnosed.