Diabetes Insipidus in Cats
Diabetes insipidus is a relatively rare variation of diabetes that is not related to the hormone, insulin. It causes cats to drink large amounts of water and urinate often, and it’s caused by the body’s inability to produce or use a hormone called vasopressin, which is an antidiuretic. The condition is not preventable — if a cat’s going to get it, a cat’s going to get it. But hormone treatment is available and with some lifestyle adjustments even an untreated cat can live a long and relatively normal life.
When most of us think about diabetes, we think of a condition called diabetes mellitus. This is a disease in which the body either doesn’t make an adequate amount of the hormone insulin or is unable to use its available insulin effectively. The result is an inability to regulate the body’s blood sugar level.
Diabetes insipidusoccurs when the body is unable to produce an adequate amount of the hormone vasopressin (also called antidiuretic hormone [ADH]) or when the available vasopressin is not being used properly.
Normally, ADH is produced by the brain, enters the bloodstream, and affects several areas of the body, particularly the kidneys. ADH helps the kidneys retain water, which is necessary for keeping the body adequately hydrated. Diabetes insipidus occurs when the body doesn’t have enough ADH or when the kidneys can’t use it properly. The result is fluid loss by the body which ultimately leads to dehydration.
Because ADH is produced in the brain, medical conditions such as brain injury, brain inflammation, and brain tumors can sometimes interfere with the brain’s ability to produce a normal amount of the hormone. Conditions that can reduce the kidney’s ability to use ADH properly in cats include uterine and kidney infections.
Symptoms and Identification
Because ADH helps the body retain water, an inadequate amount of ADH (or an inability to use it properly) causes the body to lose too much water through urine production by the kidneys.
A very common clinical sign associated with diabetes insipidus is increased production of abnormally dilute urine. The pet responds to this water loss (dehydration) by drinking more water. Affected cats will drink in excess, urinate frequently, and may even urinate outside their litter boxes or use much more litter than normal.
In some cases, the cat may be so desperate for water that he or she stops eating (preferring instead to drink even more water) and begins to lose weight. Some cats also “steal” water from various sources around their homes.
Veterinarians tend to begin the diagnostic process by obtaining a thorough medical history and performing a physical examination. Initial diagnostic tests may include a chemistry panel, a CBC (complete blood cell count), a thyroid hormone test, and urinalysis. These tests can help rule out kidney disease, thyroid disease, diabetes mellitus, and other medical conditions that tend to make cats drink more water and urinate excessively. If there is an underlying medical condition that may be causing diabetes insipidus, such as uterine or kidney infection, investigation of the underlying problem will likely be part of the diagnostic process.
Advanced testing for diabetes insipidus may include additional blood testing and urinalysis as well as a specific test to determine if a cat’s kidneys are able to produce concentrated urine. This test may require that the cat spend a day or more in the hospital. As part of the diagnostic plan, some veterinarians administer desmopressin (a synthetic replacement for ADH) to measure how the patient responds to ADH replacement.
No breed predisposition has been reported for diabetes insipidus in cats.
Synthetic ADH substitutes are available for use in cats. Some of these agents are administered by injection, but most formulations are administered as drops into the eyes or nose. Feeding pets sodium-restricted diets may also be part of the recommended therapy for diabetes insipidus.
Some pet owners may elect not to treat diabetes insipidus. In these cases, cats must have unrestricted access to water at all times. If water is restricted in any way, pets can quickly become dehydrated and suffer life-threatening complications. Also, the home environments and daily routines must be modified to allow for frequent urination. This may include purchasing additional litter boxes and changing them more frequently.
With treatment, cats with diabetes insipidus can live normal life spans and enjoy relatively normal lives. Untreated cats can also do very well as long as plenty of water is always available.
There is no known prevention for diabetes insipidus in cats.
This article has been reviewed by a Veterinarian.