Diabetes insipidus is a rare condition that affects how dogs regulate their body's water balance. Unlike the more common diabetes mellitus (sugar diabetes), diabetes insipidus has nothing to do with blood sugar. Instead, it affects how the body manages water through the antidiuretic hormone (ADH). Generally, the body does not produce ADH or it does not respond to ADH resulting in inability of the kidneys to retain water and subsequent diabetes insipidus. This condition causes dogs to produce large amounts of dilute urine and experience excessive thirst.  

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There are two main types of diabetes insipidus in dogs. Central diabetes insipidus occurs when the brain does not produce enough ADH. This can happen due to head trauma, tumors, or other conditions affecting the brain including some viral infections. Nephrogenic diabetes insipidus develops when the kidneys do not respond properly to ADH, even though normal amounts are being produced. This type can be idiopathic (cause unknown) or because of an underlying health condition.

The most noticeable signs are dramatic increases in thirst and urination. Dogs with this condition may drink excessive amounts of water. You may struggle to control their thirst and find you are constantly filling up their water bowl. You might notice your dog asking to go outside more frequently or having accidents in the house. The urine is typically very clear and dilute. Dogs may also become dehydrated if they cannot drink enough water to replace what they are losing through urination, this can result in serious medical problems. Dogs with diabetes insipidus become dehydrated quickly and although it is frustrating that they need to urinate so often, or they have accidents, restricting their water can cause dehydration so severe it can lead to a coma.

Your veterinarian will first perform a thorough physical examination and gather a detailed history of your dog's symptoms. They will likely recommend blood tests and urinalysis to rule out other conditions that can cause increased drinking and urination. If your veterinarian suspects it is caused by a head trauma or injury, they may recommend imaging tests to help identify the cause. There is no specific test for diabetes insipidus, and its diagnosis is made through exclusion of other causes and response to a synthetic form of ADH, or challenging your pet with controlled water intake while monitoring urine concentration (modified water deprivation test) which can help determine which type of diabetes insipidus is present. The modified water deprivation test can be dangerous and careful monitoring must be done in the hospital by trained veterinarian and veterinary staff to avoid serious complications.

Treatment depends on the type of diabetes insipidus your dog has. For central diabetes insipidus, synthetic ADH (desmopressin) can be given as drops in the eye or by tablets. This medication helps the body retain the right amount of water. For nephrogenic diabetes insipidus, treatment focuses on managing the underlying cause if possible and may include dietary changes or other medications to help reduce urine production. This can include tablets such as chlorthiadzide diuretics, anti-diuretics or non-steroidal anti-inflammatory drugs, but the best treatment will be recommended by your veterinarian depending on the cause. It is important to follow your vets directions carefully and ensure your dog receives their medication. Find a tasty treat, that your dog enjoys, and try hiding their medication in this. Be aware that dogs are clever and may start to refuse the treat if they are suspicious that there is a tablet hidden. Change the selected treat, on a regular basis. Your veterinarian may recommend a low sodium diet, especially if your dog has nephrogenic diabetes insipidus, as this will relieve some of the pressures on their kidneys. Your veterinarian will be able to discuss the best diet and treats for your dog with you.

The most important aspect of home care is ensuring your dog always has access to fresh water. Never restrict water intake, unless specifically instructed by your veterinarian, as this could lead to dangerous dehydration. You may need to provide your dog with several water bowls or increase the size of their water bowl. Watch for signs of dehydration such as dry gums, loss of skin elasticity, or lethargy. Keep track of how much your dog drinks and urinates, as changes in these patterns could indicate the need for medication adjustment. You should let your dog out to the toilet regularly, and if you are going out you may need to arrange to have a dog sitter take your dog out to go to the toilet. It can cause a lot of distress for trained dogs to have accidents in the house and it should be avoided where possible. Never shout or punish your dog if they have an accident in your home.

Contact your veterinarian immediately if you notice any of these signs:

• Sudden changes in drinking or urination patterns.
• Signs of dehydration despite drinking normally.
• Lethargy or decreased appetite.
• Vomiting or diarrhea.
• Confusion or disorientation.
• Inappetence or decreased appetite.

With efficient diagnosis and treatment, most dogs with diabetes insipidus can live normal, healthy lives - but this is dependent on the cause. Regular veterinary check-ups and careful monitoring at home are essential. Traumatic diabetes insipidus can improve in as little as 2 weeks as inflammation around the injury decreases, but it does depend on how severe the injury is. Idiopathic or central diabetes insipidus requires lifelong treatment but patients usually respond well. Dogs with nephrogenic, untreated central diabetes insipidus or diabetes insipidus caused from a brain tumor may not recover and it can lead to a deceased quality of life for dogs and their care plan should be carefully managed with a veterinarian.