Evans syndrome is a combination of IMHA (immune-mediated hemolytic anemia) and IMTP (immune-mediated thrombocytopenia). This means a pet’s body attacks the red blood cells and platelets at the same time.
Evans syndrome was first identified by Dr. Robert Evans in 1951 and is most common in middle-aged female dogs, particularly Cocker Spaniels, German Shepherds, Poodles, and Old English Sheepdogs. However, it can affect any animal regardless of age, sex, or breed. Let’s learn more about this condition.
What is Evans Syndrome in Animals?
Evans syndrome is a very rare and serious autoimmune disease in animals, especially dogs and cats. It occurs when the immune system attacks the red blood cells and platelets, causing immune-mediated hemolytic anemia (IMHA) and immune-mediated thrombocytopenia (IMTP).
- Immune-mediated Hemolytic Anemia (IMHA): This means the immune system destroys the red blood cells and causes anemia. Unfortunately, IMHA has a high mortality rate of about 70% so it needs a very aggressive treatment.
- Immune-mediated Thrombocytopenia (IMTP): This means the immune system attacks platelets, responsible for blood clotting.
As we already mentioned, Evans syndrome is one of the things dogs and cats have in common. We still don’t know what causes this condition in pets, but experts have a few possible triggers in mind, such as infections, vaccines, genetic factors, or even cancers. So, watch out for signs of cancer in dogs and cats.
Symptoms of Evans syndrome in animals:
- Pale gums, eyes, and genital area
- Lethargy and weakness
- Rapid breathing and heart rate
- Yellowing of the skin or eyes
- Petechiae or bruises on the skin and mucous membranes, nose or mouth bleeding
- Blood in urine or feces
- Collapse due to anemia and bleeding
- Fever
- Enlarged spleen
- Low red blood cell and platelet counts
- Abnormal blood smear
If you suspect your pet has Evans syndrome and you’re a new pet owner, don’t worry. Just prepare for your first veterinary appointment and share your concerns with your vet.
Evans Syndrome Diagnosis
Vets diagnose Evans syndrome using several steps:
- Blood tests: Detect low red blood cell count (IMHA) and low platelet count (IMT). These tests help identify the immune system’s attack on blood components.
- They examine the bone marrow: Issues in the bone marrow can indicate underlying problems contributing to the syndrome.
- Coombs’ test: Confirm the immune system is destroying red blood cells, which is a key feature of IMHA.
- Platelet count: Identify low platelet levels (thrombocytopenia) to diagnose IMT.
Your vet will likely conduct additional tests to rule out other causes of anemia and low platelets for a more accurate diagnosis.
Keep in mind that all of these tests cost a lot, so it’s a good idea to get pet insurance. The cost of pet insurance is small compared to what you will have to pay for treatments and medical care in case of a disease.
Evans Syndrome Treatments
The treatment for Evans syndrome depends on the animal and their condition. Some of the common treatments include:
Corticosteroids
Corticosteroids (like prednisone) can calm down the immune system. They help stop the body from attacking the red blood cells and platelets. Sometimes, other medicines like azathioprine, cyclosporine, or mycophenolate mofetil can help the immune system calm down and protect the blood cells.
Blood transfusion
In very serious cases, your pet might need a blood transfusion. This helps manage the low red blood cells and supports them until other treatments start working.
Intravenous immunoglobulin (IVIG)
This helps stop the immune system from attacking their red blood cells and platelets.
Plasmapheresis
In the most serious cases, a treatment called plasmapheresis might be used. It cleans harmful things from the blood and puts in healthy plasma from a donor. This is done in special veterinary hospitals.
Evans Syndrome Prognosis
How well your pet does with treatment can vary a lot. Some pets do well with treatment and can live a pretty normal life with good care. Others might have more problems, like coming back with the same issues or other complications.
Finding out about Evans Syndrome early and starting treatment quickly usually gives pets a better chance of feeling better. In summary, Evans Syndrome often means your pet will need regular check-ups and medicine for the rest of their life.
Evans Syndrome Causes
Causes of Evans syndrome in pets include genetics, infections like Babesia in dogs and Mycoplasma haemofelis in cats, certain medications, vaccinations, underlying diseases such as cancer or lupus, and environmental factors like toxins.
- Genetic predisposition: Certain breeds, like Cocker Spaniels, have a higher chance of developing autoimmune diseases due to their genes.
- Infections: Infections from organisms such as Babesia in dogs and Mycoplasma haemofelis in cats can cause problems with their immune system, damaging their blood cells.
- Medications: Some drugs, like sulfur drugs in dogs or antithyroid medications in cats, can affect how their immune system works. This can increase their chance of developing Evans Syndrome over time.
- Other diseases: Evans Syndrome can also be caused by common cancers in dogs and cats, lupus, or problems with the immune system, which can make the body attack itself.
- Environmental Factors: Things like toxins or allergens in their environment might also make their immune system act up, especially if they’re genetically prone to autoimmune problems.
- Vaccinations: While vaccines protect pets from various diseases, experts suspect that recent ones might cause Evans syndrome in susceptible pets.
Final Tips
Evans Syndrome is serious but regular vet check-ups and careful care can help your best friend, whether a cat or dog, stay well.
We also suggest working closely with your vet to find the lowest amount of medicine that still works well. This helps minimize any side effects.
Also, never change or stop their medicine without talking to your vet first and watch out for possible side effects from their medicine, like more thirst or hunger, and tell your vet right away if you notice anything unusual.
