PK Deficiency in Maine Coons: The Silent Anemia#

We often joke that Maine Coons are “lazy giants.” They sleep 16 hours a day, they flop on the floor, and they act like throw rugs. But sometimes, that lethargy isn’t a personality trait—it’s a sign that their blood cells are dying faster than their body can replace them.

Pyruvate Kinase Deficiency (PK Def) is one of the trickiest genetic diseases in the breed because it comes and goes. A cat can look fine one month and be severely anemic the next.

Unlike SMA (which affects walking) or HCM (which affects the heart), PK Def affects the energy source itself: the red blood cells.

What is Pyruvate Kinase?#

Pyruvate Kinase is an enzyme. Its job is to help red blood cells metabolize energy.

Red blood cells are the delivery trucks of the body, carrying oxygen to the muscles and organs. To keep trucking, they need fuel. Without this specific enzyme, the red blood cells run out of gas and die prematurely.

Normal lifespan of a cat red blood cell: ~70 days.
PK Def lifespan: Significantly shorter.

When the blood cells die too fast, the cat becomes anemic. The bone marrow tries to panic-produce more cells to catch up, but eventually, it can’t keep pace.

Symptoms: The “Intermittent” Illness#

This is what makes PK Def so frustrating to diagnose without a DNA test. The anemia is intermittent.

A cat might have a “crisis” where they are lethargic, pale, and weak. Then, their bone marrow kicks into overdrive, replaces the cells, and the cat seems “cured” for a few months. Owners often dismiss the episodes as “he just had a bug” or “he was tired.”

Signs to Watch For:

Extreme Lethargy: Not just napping, but refusing to play or move.
Pale Gums: Lift the lip. The gums should be bubblegum pink. If they are porcelain white or grey, that is anemia.
Pica: Eating non-food items (like litter or concrete) is sometimes a sign of anemia (see our Pica Guide).
Jaundice: Yellowing of the eyes or skin (rare, usually late-stage).

The Genetics: Carriers vs. Affected#

Like SMA, PK Def is Autosomal Recessive.

N/N (Negative): No copies of the gene. Safe.
N/K (Carrier): One copy. IMPORTANT: Unlike SMA carriers, PK Def carriers can typically live normal lives, but they should NEVER be bred to another carrier.
K/K (Affected): Two copies. This cat will have the disease.

The Breeder’s Responsibility: It is actually acceptable to breed a Carrier (N/K) to a Clear (N/N) cat. The kittens will not be affected (though some will be carriers). This is done to preserve genetic diversity (keeping the gene pool wide) while ensuring no sick kittens are born. However, two carriers must never be bred.

Treatment and Prognosis#

There is no cure for PK Def. If a cat is affected, the treatment is supportive care. During severe anemic episodes, they may need blood transfusions. In some cases, a splenectomy (removing the spleen) helps, as the spleen is where the damaged blood cells are destroyed.

The lifespan of an affected cat varies wildly.

Some die young (before 4 years) due to liver failure or severe anemia.
Some live to be 12+ years old with only mild symptoms. It is a genetic roulette wheel.

The Bottom Line#

If your Maine Coon seems perpetually tired, “lazy,” or has pale gums, ask your vet for a standard blood panel (CBC) to check for anemia. If they are anemic, ask specifically for the PK Def DNA test.

And, as always, prevention is the only cure. When buying a kitten, ask to see the PK Def status of the parents. “I think they’re healthy” is not a medical diagnosis.

References#

Grahn, R.A. et al. (2012). “Erythrocyte Pyruvate Kinase Deficiency mutation identified in multiple breeds of domestic cats.” BMC Veterinary Research.
Langford Vets. PK Deficiency Testing Information.
Abood, S.K. (2018). Feline Anemia and Genetic Disorders.
TICA Genetics Committee. PK Def Screening Recommendations.
UC Davis Veterinary Genetics Laboratory. Pyruvate Kinase Deficiency (PK Def).