Signs of Dehydration in Dogs and Cats

Dehydration becomes a real concern anytime a pet is losing fluid faster than they're replacing it — most commonly from vomiting, diarrhea, reduced water intake, heat exposure, or a combination of these. Recognizing the signs early matters because dehydration, left unaddressed, affects organ function and can become serious relatively quickly, particularly in small pets, puppies, kittens, and seniors.

A simple at-home check is the skin tent test: gently pinch a small fold of skin between the shoulder blades and release it. In a well-hydrated pet, the skin should snap back into place almost immediately. If it returns slowly, or stays tented for a moment before flattening, that suggests meaningful dehydration. This test is less reliable in older pets whose skin has naturally lost some elasticity with age, so it's not perfect, but it's a useful quick check.

Other signs include dry or tacky gums (healthy gums should feel moist and slick), thick or ropey saliva, sunken-looking eyes, lethargy, and in more advanced dehydration, weakness or collapse. Reduced skin elasticity combined with dry gums and lethargy together is a stronger signal than any single sign alone.

What to do: If you notice signs of dehydration, especially alongside ongoing vomiting or diarrhea, offering small, frequent amounts of water (rather than letting a dehydrated pet gulp a large amount at once, which can trigger more vomiting) is a reasonable first step while you contact a vet. Moderate to severe dehydration signs — noticeably slow skin tent return, lethargy, or weakness — warrant prompt veterinary attention, since IV or subcutaneous fluids may be needed to correct it faster and more safely than oral rehydration alone.

This risk is exactly why vomiting and diarrhea happening together carries more urgency than either symptom alone.