Dog dehydration
A dog can become dehydrated quickly from vomiting, diarrhoea, heat, or not drinking, and in puppies, small dogs, and seniors it can become serious fast. Signs include tacky or dry gums, lethargy, sunken eyes, and skin that is slow to spring back when gently lifted. If your dog is also vomiting, cannot keep water down, is weak, or has ongoing diarrhoea, call a veterinarian — they may need fluids. Offer small, frequent sips of water while you arrange care, but do not force water into a weak or collapsing dog.
Go to a vet now if
- Weakness or collapse with dry, tacky gums and sunken eyes
- Skin that stays tented when gently lifted
- Unable to keep water down, or ongoing vomiting and diarrhoea
- A puppy, small, or elderly dog that is dull and not drinking
Call a vet today if
- Mildly reduced drinking in a bright dog that is otherwise normal
- Slightly tacky gums on a warm day that improve with water and rest
What to tell the vet
- What is causing fluid loss (vomiting, diarrhoea, heat)
- How long and how severe
- Whether your dog can keep water down
- Gum feel and energy level
- Your dog's age, weight, and size
- Any conditions or medications
What not to do
- Do not force large amounts of water on a weak or vomiting dog — offer small sips
- Do not give human electrolyte drinks without veterinary advice
- Do not ignore dehydration in a puppy or senior — they decline fastest
What your vet may check
Your vet will assess how dehydrated your dog is, look for the underlying cause, and may give fluids under the skin or into a vein. Addressing the cause — such as vomiting or diarrhoea — is part of the plan.
Recovery support after veterinary assessment
As your dog recovers, your vet may advise a gentle return to food and continued hydration. Supportive options positioned for recovery, such as Alfavet ReConvales for appetite or DiaTab for an unsettled gut, may be suggested on veterinary advice.
Frequently asked questions
How can I tell if my dog is dehydrated?
Check for dry or tacky gums, lethargy, sunken eyes, and skin that is slow to return when gently lifted between the shoulders. If you see these, contact your vet.
When is dehydration an emergency?
When your dog is weak or collapsing, cannot keep water down, or has ongoing vomiting or diarrhoea — especially in puppies, small dogs, and seniors — it needs urgent care.
Can I rehydrate my dog at home?
Offer small, frequent sips of water for mild cases, but do not force fluids. If signs are more than mild or your dog is unwell, a vet may need to give fluids directly.
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Sources & standards
Emergency guidance follows AVMA, Merck Veterinary Manual, ASPCA Animal Poison Control, and small-animal emergency-medicine standards, reviewed by our veterinary advisory board.