Immune mediated haemolytic anaemia (IMHA) in dogs

dog on white background


IMHA is a condition of the blood that causes severe anaemia. IMHA causes the body (more specifically the immune system) to attack and destroy its own red blood cells. It’s most common in middle-age dogs (4-7 years old) and pedigrees.

IMHA can develop either very slowly or very quickly. If it develops slowly, your dog may just appear a bit quiet or low on energy. If it happens quickly your dog may develop pale gums, rapid breathing and might even collapse.

Although IMHA is a serious condition, treatment is usually successful if it’s given quickly.

Description of condition

IMHA is a disease where a dog’s immune system attacks its own red blood cells. Red blood cells are very important because they carry oxygen around the body. A dog with IMHA will become anaemic (low in red blood cells), they will look pale and become very poorly.


  • Low energy (lethargy)
  • Weakness and sometimes collapse
  • Pale pink, white or yellow gums
  • Pale or yellow around the eyes
  • Jaundiced skin (yellow colour)
  • Fast breathing
  • Reduced appetite
  • Unexplained bleeding.

The signs of IMHA can vary depending how quickly and severely your dog is affected. If IMHA comes on slowly you may just notice your dog being quieter than normal, having less energy or not being quite themselves. If IMHA comes on quickly you may notice some of the more serious symptoms listed above.

Photo of pale gums in a dog

Pale gums in a dog

When to contact your vet

IMHA is a serious disease. Have your dog checked if they seem quiet or low on energy. Symptoms such as collapse, breathing faster than usual or pale gums are an emergency and you should contact your vet immediately.

You know your dog best. If they don’t have the symptoms listed above but you are still concerned it’s always best to contact your vet.


IMHA happens when your dog’s immune system goes wrong, instead of protecting the body it mistakenly attacks and destroys its own red blood cells. Most of the time we never find out what caused the immune system to make this mistake.


Your vet will be able to diagnose the problem by examining your dog and taking some blood samples. Once IMHA has been diagnosed treatment usually involves a stay in a vet hospital until your dog is out of danger.

Treatment can include:

A drip

  • Fluids put directly into the bloodstream keep your dog hydrated and protect vital organs while they aren’t eating or drinking.

Blood transfusion

  • If your dog is very anaemic (very low in red blood cells) a blood transfusion may be needed to save their life.


  • Extra oxygen is sometimes provided to help the surviving red blood cells carry as much oxygen as possible around the body.


  • (Immunosuppressants) will be given to stop the body destroying red blood cells. Other drugs may also be given to help your dog recover.

Once your dog’s immune system stops destroying red blood cells, the body can start to make replacement cells and your dog will be able to slowly get better.

Ongoing care

Once your dog has started to improve they can be sent home with treatment for you to give them. When your dog comes home make sure you keep them comfortable, warm and feed them a good balanced diet. Make sure you give all the medication prescribed. This could include medication and dietary supplements to help your dog produce new red blood cells.

Speak to your vet about how much exercise your dog needs during their recovery – it’s likely they won’t want to or be able to go for their normal walks until they are much better.

Most dogs have to stay on treatment for several months until they have fully recovered.


Most dogs, even if they are very poorly, will get better with treatment from your vet. Sadly some dogs become so poorly with IMHA they don’t survive. IMHA can happen more than once so if your dog has had IMHA previously, keep an eye out for it happening again.

Published: October 2018

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Written by vets and vet nurses. This advice is for UK pets only.

Illustrations by Samantha Elmhurst