What Is Dehydration?
Dehydration is a deficiency of total body water that occurs when fluid losses exceed fluid intake. In pets, it is commonly caused by vomiting, diarrhoea, fever, or inadequate water consumption. Mild dehydration is manageable at home, but dehydration above 8–10% of body weight is a medical emergency requiring intravenous fluids.
Understanding Dehydration
The quickest at-home test for dehydration is the skin tent test: gently pinch the skin at the back of the neck, then release. Normally, skin snaps back within one second. Dehydrated skin returns slowly or stays tented — the longer it takes, the more severe the dehydration. A second test: press your finger against the gum to blanch it, then release — normal colour should return within 2 seconds (capillary refill time).
Cats are particularly prone to dehydration because they have a lower natural thirst drive than dogs. They evolved as desert animals that obtained most of their moisture from prey, not from drinking free water. This is why a dry food-only diet places cats at higher chronic dehydration risk, and why urinary and kidney problems are so prevalent in cats. Wet food and water fountains are important dehydration management tools for cats.
At the veterinary clinic, dehydration is assessed and confirmed by blood tests (elevated BUN, creatinine, and packed cell volume are all markers) and treated with fluid therapy — either subcutaneous fluids (under the skin) for mild to moderate cases or intravenous fluids for severe or acute cases. The underlying cause must also be identified and treated to prevent recurrence.