Many of us are familiar with diabetes mellitus, which affects the way sugar is processed in the body. While that is definitely more common, there is another rare form of diabetes our pets can get, called diabetes insipidus. Diabetes insipidus is completely separate from diabetes mellitus, and affects the body completely differently as well. Diabetes insipidus (DI) affects the way water is processed in the body. It is also known as water diabetes, or even just the “other diabetes”. DI prevents water conservation, causing the body to release too much of the fluids that are being taken in. Symptoms of DI are increased urination, increased thirst and water intake, diluted urine, soiling in the house, poor hair coat, and dehydration. Simply put, no matter how much water your pet drinks, it is just being flushed out; not hydrating the body at all.
There are two types of DI, although the external symptoms are the same. The first type is neurogenic, or central DI. This is when there is a lack of the hormone vasopressin, which regulates water conservation. Vasopressin, also known as ADH (antidiuretic hormone), is created and regulated in the hypothalamus and pituitary gland. A brain tumor, head injury, or failure of the pituitary gland could all cause neurogenic DI. The second type of DI is nephrogenic, where the failure is not in the brain, but in the kidneys. Plenty of vasopressin/ADH is being produced and transported, but the cells in the kidneys are not responding to it. Kidney problems like cysts or amyloidosis (abnormal buildup of proteins), or kidney failure are often the cause of nephrogenic DI.
Diagnosis of diabetes insipidus sometimes requires hospitalization. The vet will collect blood and urine samples to test, and may use imaging (like an MRI or CT scan) to check for possible tumors or damage. While hormone levels are easy to check in the blood, the final diagnosis usually comes from a water deprivation test. Your pet will be tested to see if they can produce more concentrated urine when water is withheld, all while their vitals are monitored. The vet may also choose to test the effectiveness of vasopressin injections at this time. Sometimes a vet will test for other problems such as a urinary tract infection, hyperthyroidism, diabetes mellitus, or Cushing’s disease, to rule out a more serious problem.
Treatment of DI will depend on the cause. Neurogenic DI can be treated with synthetic hormones to replace the lack of vasopressin. These can be given via injection, nasal spray, or eye drops. Nephrogenic DI has to be treated by first dealing with the underlying cause. This may require surgery to remove tumors, treatment of kidney failure, or other remedies. No matter the type of diabetes inspidius, there are things you should do at home as well to help your pet. NEVER LIMIT THEIR WATER. Even if they seem to be drinking “too much” (often laying in front of their bowl drinking until it is gone), or have soiled the house, you cannot limit their water intake. Always have plenty of clean, fresh, water out for your pet. You will also need to provide more urination options for them as well. A cat will need two or three more litter boxes, and a dog would benefit from a dog door into a fenced yard. Your pet should always be monitored for signs of dehydration as well.
While diabetes insipidus is a permanent condition, it is also treatable and not fatal alone. When your dog can’t stop obsessively drinking water, and is urinating far too frequently, it may be time for a vet to check for water diabetes!
Sources: PetMD, Merck Veterinary Manual, VCA Animal Hospitals, caninediabetes.org