Polycythemia in Cats

Learn about polycythemia in cats, a rare condition resulting from too many red blood cells.

Polycythemia in cats is rare. I never heard of it until a vet diagnosed one of my fosters, Binti, with it. Here is a quick overview of the disease and treatment, intermingled with my personal experiences.

What Is Polycythemia in Cats?

Bone marrow makes red blood cells. You’ve probably heard of anemia, when there are too few red blood cells. Polycythemia is the opposite: There are too many red blood cells, causing the blood to become thick and viscous. This impacts blood flow and can cause major issues in the body, especially in the brain and muscles. Since they require a lot of nutrients and oxygen to work properly, cats with polycythemia may be less active and can have seizures because of decreased blood flow to the brain.

Meet Binti

Shaved cat
Binti was shaved after overgrooming due to stress.

My foster Binti had been to the city shelter 4 times. She had lost her home because of a baby, a fire, and owners not liking her personality. This time, she sostressed at the shelter she overgroomed so badly the staff shaved her. She was timestamped for euthanasia with no rescue interest. I was at the shelter and met her, and fell in love with her. She was a sweet girl, she’d just had a very rough life. I reached out to a rescue I work with, Whiskers of Love, and they agreed to help me pull her out of the shelter. Once she was in my home, she was affectionate, loving, and a joy to be around. I couldn’t even make sense of her difficult past and how anyone could give up a cat that just wanted love.

Strange Happenings

The vet took Binti’s blood twice. Both times the lab had issues, saying they needed more blood. This is what likely happened. Since the blood was sent out and not processed in house, it sat. The thick blood clotted in the vials by the time it reached the lab. There was no way for us to have known this was what happened. We thought we were just really unlucky and the lab had two errors in a row.

I came home from work one day and found Binti had peed on the floor (unlike her) and she was just laying in the corner (also unlike her). She was acting very strange, so I took her to the ER. I learned that she’s had a seizure and what I was seeing was called the postictal state. Five to 30 minutes after a seizure, there is a lot of confusion and disorientation as the body returns back to its balanced state. We can only imagine how much extra an animal is since no one can even explain to them what just happened.

What Are the Causes of Polycythemia

Polycythemia in cats can be primary, meaning it is the main issue. We do not know what causes this to occur in cats, so it seemingly just happens, often slowly over a few months.

It can also be secondary, meaning something else is wrong in the body and causing the bone marrow to produce more red blood cells. VCA Hosiptals outlines these causes to be dehydration, heart disease, lung disease, certain kidney issues, and cancer.

Possible Cause for Binti

Given that my foster Binti’s white blood cell count was also high, it’s likely she had some sort of cancer, making polycythemia secondary to a preexisting condition.

What Are the Symptoms?

The symptoms can be extremely hard to spot, especially if they happen slowly over time. They can include fatigue, vomiting, diarrhea, excessive thirst, excessive urination, excessive bleeding, seizures, lack of coordination, personality changes, and even blindness.

Binti’s Symptoms

To my knowledge, Binti only had that one seizure. I did notice she urinated a lot, which was why I was expecting her blood work to possibly show something like hyperthyroidism. However, the lab couldn’t test the blood and I was in the process of trying to get a urine sample at home. Every time she was at the vet, her bladder was empty, so they couldn’t take urine. We just never got far enough to diagnose before the seizure. She also had two instances where she threw up and there was a little blood in it (it was pinkish). This is not uncommon. Cats that vomit may have blood in their vomit related to inflammation in her stomach. I now know GI bleeding can be related to polycythemia, but there was no way to know at the time that it was the cause of her mild symptoms.

What Is the Treatment for Polycythemia in Cats?

There are two parts to treatment:

  1. Phlebotomy – A process where they remove a portion of the cat’s blood and administer fluids to thin out the blood. They repeat the procedure until the red blood cells are at a good level.
  2. Hydroxyurea – Cats starts on a high dose of this medication, which slows the bone marrow’s ability to product red blood cells. It takes time for this medication to work. Vets monitor the cat weekly, then monthly for 3 months, then every 3 months. Some pets are weaned after 1-2 years, but other need the medication for life.

If polycythemia is secondary, the preexisting condition (ex. cancer) is treated.

No Treatment for Binti

To go through a phlebotomy, it’s important that a cat can easily be handled because the process is very involved. It requires many follow up appointments, possibly more phlebotomies, blood tests, etc. Unfortunately, Binti was a nightmare at the vet, and barely allowed any handling.

There was also the main issue that another illness, probably cancer, caused Binti’s problems. At her age (estimated 10-12 years) and with how much the polycythemia had progressed, putting her through more treatment didn’t seem like the right decision for her well being. If we found the main cause (which would require more testing), could we even treat it? Likely not easily.

Tortoiseshell cat resting
The vet gave Binti meds to relax her because she was very aggressive at the hospital. I’m so glad I got to say goodbye.

I couldn’t take her home because she was at risk for a grand mal seizure overnight, so I, along with the vets and Whiskers of Love rescue, decided to let her go peacefully. I held her as she passed; I was heartbroken, but I knew we’d done everything right by her.

The last moments Binti and I spent together before she peacefully passed in my arms.

As I like to say, I can’t always provide the outcome I want, but I can give the cat the outcome they need.

By LizsKittyBootCamp

Hi, I'm Liz, and I'm a cat behaviorist who provides advice and insights on cat behavior.

2 replies on “Polycythemia in Cats”

Thank you for sharing! My kitty is going through this right now and I appreciate the honesty and all the information!

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