Diabetes insipidus (DI) is a rare disease in cats that should not be confused with diabetes mellitus, or sugar diabetes.
• DI results from a failure of normal antidiuretic hormone (ADH) signaling
• Cats that do not produce ADH, or whose kidneys that do not respond to ADH, continuously produce urine which can lead to dehydration due to excessive water loss in the urine
• The main symptoms of diabetes insipidus are excessive urination and drinking
• Cats that become severely dehydrated have tacky gums, sunken eyes, and severe lethargy and require immediate veterinary attention
• Diagnosis of diabetes insipidus involves urinalysis, blood tests, and testing the body’s response to ADH
• Treatment depends on the root cause of ADH signaling failure
• Most cases of diabetes insipidus have a good prognosis with appropriate treatment
There are two forms of diabetes insipidus: central (originating from the brain) and nephrogenic (originating from the kidneys).
Central diabetes insipidus occurs when there is damage to the hypothalamus, a part of the brain that produces antidiuretic hormone. When the hypothalamus is damaged, ADH is not produced, leading to excessive urination. The most common causes of hypothalamus damage are brain tumors, infections, and injuries. In some cases, cats develop central diabetes insipidus without any obvious cause.
Nephrogenic diabetes insipidus occurs when the kidneys do not respond to antidiuretic hormone appropriately. This produces the same effect of excessive urination, even though ADH is present. Most cases of nephrogenic diabetes insipidus occur due to an underlying health condition. In rare cases, cats are born with a defect in their kidneys that prevents an appropriate ADH response
Diabetes insipidus is very rare in cats. In most cases, diabetes insipidus is not life-threatening and has a good prognosis with appropriate treatment. Cats that show signs of severe dehydration such as tacky gums, severe lethargy, and sunken eyes require immediate veterinary attention, as prolonged dehydration can lead to coma and death.
Cats with diabetes insipidus are frequently dehydrated, as they are unable to consume enough water to compensate for their excessive urination. Symptoms of dehydration include:
• Tacky or dry gums • Lethargy • Sunken eyes
Cats that have brain tumors associated with diabetes insipidus often have other symptoms, such as:
• Uncoordinated gait (ataxia) • Severe lethargy • Seizures • Tremors • Abnormal behavior
DI is caused by either lack of ADH production or lack of response to ADH that is present. Health conditions associated with diabetes insipidus include:
• Hyperadrenocorticism • Pyelonephritis • Chronic kidney disease
The most common symptoms of diabetes insipidus are:
• Excessive urination (polyuria) • Excessive drinking (polydipsia)
Diabetes insipidus is very rare, so ruling out other causes of excessive urination is usually the first step in diagnosis. Diagnostic tests include:
• Blood tests • Urinalysis • Hormone level testing • Imaging such as X-rays or ultrasound
Specific tests to confirm a suspicion of diabetes insipidus include:
Water deprivation test: Water is withheld from the cat for 3-8 hours. After this period, the concentration of the cat’s urine is assessed. Cats with diabetes insipidus continue to have poorly concentrated urine (i.e. excess water), even when dehydrated.
ADH response test: A dose of ADH is given to the cat, followed by monitoring of urine concentration. If the cat’s urine concentration increases, then central diabetes insipidus is diagnosed. Cats that do not respond to the dose of ADH are presumed to have nephrogenic diabetes insipidus.
The outcome of diabetes insipidus depends on the origin of the disorder. Diabetes insipidus resulting from decreased ADH production is a lifelong condition. These cases have a good prognosis with appropriate treatment. Treatment involves administering ADH daily or twice a day for the remainder of the cat’s life.
Nephrogenic diabetes insipidus often resolves when the underlying condition is treated. Most underlying conditions that cause nephrogenic diabetes insipidus have a good prognosis with appropriate treatment.
Diabetes insipidus is not contagious. Since this condition is associated with various types of kidney disease, it is not easily prevented as kidney disease is often congenital and develops with age. Keeping up with annual vet check ups for adult cats helps to identify congenital conditions and start treatment early, which improves health outcomes.
Diabetes insipidus is rare in cats.
• Supplemental ADH • Specific treatment for underlying conditions
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