Pyruvate Kinase Deficiency in Cats

Pyruvate Kinase is a condition that seems to affect certain breeds more than others. Cats with the disorder have a deficiency in enzymes known as Pyruvate Kinase or PK which damages their red blood cells. It prevents the blood cells from metabolising which leads to cats developing anaemia as well as other issues that affect the blood. Pyruvate kinase deficiency is a hereditary disorder and any cats that are known to suffer from the condition or which have tested as being carriers should never be used in a breeding programme because they could pass the disorder on to their offspring.

Breeds Most at Risk

As previously mentioned, some breeds appear to be more predisposed to developing Pyruvate Kinase than others and this includes the following breeds:

• Abyssinian
• Somali
• Mixed Breed / Moggy
• Bengal
• Eyptian Mau
• LaPerm
• Maine Coon
• Norwegian Forest
• Savannah
• Siberian
• Singapura

Symptoms to Watch Out For

When cats develop the condition, the signs of there being something wrong with them could include the following:

• Anaemia whether mild or more severe
• Weakness/lethargy
• Muscle wastage
• Pale gums and other mucous membranes
• An elevated heart rate which is referred to as tachycardia
• Unable to move around normally
• Jaundice - one of the rarer symptoms

The Causes

The disorder is a genetic defect which kittens are born with having inherited PK Def from their parents. It is caused by what is known to be an autosomal recessive gene which in short, means cats can be affected or they can be carriers and as such they can pass the disorder on to their offspring. Sometimes an affected cat may not show any symptoms of having the condition until they reach their senior years whereas others are more seriously affected much earlier on and the disorder is then considered to be life-threatening.

Diagnosing the Problem

A vet would need to have a cat's full medical history and ideally, they need to have a cat's ancestry too. Vets also need to know how the onset of a cat's symptoms first manifested themselves before they would carry out a full physical examination. Other tests a vet would likely recommend doing to confirm their diagnosis could include the following:

• A biochemistry profile - this would determine if iron levels are high in a cat's blood stream which is referred to as hyperferremia. The test would also establish if there's an increase in levels of bilirubin and enzymes in a cat’s liver
• A complete blood count (CBC) - this would determine if a cat has increased platelet levels and white blood cells known as leukocytosis. It would also establish to what extent a cat is suffering from anaemia
• A urinalysis - this would determine if bilirubin levels are elevated

Treatment Options

The only viable treatment for Pyruvate Kinase in cats is a complete bone marrow transplant. The downside to this is that it is extremely expensive and it is also considered as being a life-threatening procedure in itself.

Living with a Cat with Pyruvate Kinase

A vet may have recommended carrying out a bone marrow transplant on a cat suffering from PK and if the procedure is successful, a cat can go on to lead a full and normal life. Sadly, if cats are not treated they typically succumb to the condition when they are around four years old. When untreated, cats quickly develop anaemia and fluids build up in their abdomens which eventually proves fatal.

Testing Cats for Pyruvate Kinase

Tests are now available in the UK and all breeds known to be predisposed to suffering from the condition should be screened to establish if a cat is affected, a carrier or normal. Where Somali cats are concerned, any cat registered with the GCCF must be tested for PK Def as it is compulsory. The test confirms both normal and mutant PKDef genes in cats predisposed to inheriting the disorder.

Interpreting of Test Results

When a cat is tested for the condition, it establishes whether they have the gene mutation or not and tests are interpreted as follows:

• Normal autosomal recessive PK Def genetic test result - this establishes that a cat is free of the damaging gene mutation that causes pyruvate kinase deficiency. As such, they will not suffer from the condition nor can they pass it on to their offspring
• Heterozygous autosomal recessive PK Def genetic test result - this establishes that a cat has only one copy of the damaging gene mutation. As such, the cat would be a carrier although they may never show any symptoms of suffering from the disorder themselves. They can however, pass the disorder on to their offspring and as such should be spayed or neutered when the time is right to prevent them from being used in a breeding programme
• Homozygous autosomal recessive PK Def genetic test result - this means a cat has two copies of the damaging gene mutation and as such would develop the symptoms associated with the condition. An affected cat should be spayed or neutered when the time is right to prevent them from being used for breeding purposes