Erythrocytic pyruvate kinase (PK) deficiency is an inherited haemolytic anaemia caused by variants in the PKLR gene, which encodes the glycolytic enzyme pyruvate kinase. The defective enzyme shortens the lifespan of the erythrocyte and produces haemolytic anaemia of highly variable onset and severity, from mild compensated forms to severe anaemia with lethargy, jaundice and splenomegaly.

Grahn et al. (2012, PMID 23110753) genotyped 14,179 cats from 38 breeds: the variant appears in 15 groups, with a mean frequency of 9.35 % (range 0.078 % in the Exotic Shorthair to 12.97 % in the Bengal). They recommend the test in the Bengal, Egyptian Mau, LaPerm, Maine Coon, Norwegian Forest Cat, Savannah, Siberian, Singapura, Abyssinian and Somali, as well as random-bred and domestic shorthair cats.

- Haemolytic anaemia of variable onset and severity (from asymptomatic to severe)
- Lethargy and weakness
- Jaundice
- Weight loss and poor growth
- Increased abdominal volume (splenomegaly)
- In severe cases, pallor, tachycardia and dyspnoea due to anaemia

Initially described in the Abyssinian and Somali cat; the molecular defect was attributed to a splicing defect in the R/L-PK gene (now PKLR). Grahn et al. (2012) identified the causal intronic transition and its presence in multiple breeds, and Kohn & Fumi (2008) described the clinical course in the Abyssinian and Somali.

- PK deficiency is autosomal recessive: only homozygotes are affected; heterozygotes are healthy carriers.
- Do not mate two carriers together (25 % risk of affected offspring).
- A carrier may be mated with a clear animal, prioritising clear offspring to reduce the allele.
- In the case of haemolytic anaemia of unclear cause, include PK in the differential diagnosis and request the genetic test.
- Record the results in the pedigree; the test is recommended in the breeds with the highest documented frequency.

The differential diagnosis of feline haemolytic anaemia includes haemoglobinopathies, haemotropic mycoplasmosis (Mycoplasma haemofelis), intoxications (onion, paracetamol, zinc), immune haemolysis and other enzymopathies. PK should be suspected in chronic haemolytic anaemia with reticulocytosis in predisposed breeds. There is no specific treatment; management is supportive and, in severe cases, transfusional.

1. Kohn B, Fumi C. 2008, curso clínico de la deficiencia de piruvato quinasa en gatos Abisinio y Somalí (PMID 18077199)
2. Grahn RA et al. 2012, mutación de la deficiencia de piruvato quinasa eritrocítica identificada en múltiples razas de gatos domésticos (PMID 23110753)
3. OMIA:000844 Deficiencia de piruvato quinasa felina