Pyruvate kinase (PK) deficiency is an inherited disease occasionally
encountered in Abyssinian and Somali cats, and also reported
in the domestic shorthair cat. Pyruvate kinase is an enzyme
found within red blood cells which enables them to produce
energy to survive. If this enzyme is lacking, the lifespan
of the red blood cells is significantly reduced, resulting
in a reduction in the number of red blood cells in the circulation
signs does it cause?
main consequence of the disease is the development of anaemia.
However, since the body can quickly manufacture new red blood
cells, the anaemia is usually only intermittently detectable.
Most of the time the anaemia is either only mild, or occurs
gradually, enabling the cat to adapt to the anaemia and not
show any obvious signs. Anaemia often results in only vague
signs such as lethargy and lack of appetite. However, a rapid
severe life-threatening anaemia can also develop. Although
PK deficiency is hereditary, the anaemia is usually mild and
clinical signs may not be obvious, and thus may not be noticed
until the cat is quite old.
is PK deficiency inherited?
disease is inherited as an autosomal recessive trait (see box 1). This means that a
cat can be carrying the defective gene (heterozygous) without
having any symptoms of the disease at all. Affected cats (homozygous)
arise when two carrier cats are mated with each other. Since
carrier cats remain healthy, and the anaemia of affected cats
may not be detected until they are a few years of age, the
potential exists for carrier cats and affected cats to have
had significant numbers of offspring before the disease is
identified. However, the positive side of this is that it
also means if carrier cats are identified they can still be
used for breeding as long as we ensure that they are NOT mated
with another carrier. Mating a carrier with a non-carrier
will not produce any offspring that will suffer from PK deficiency,
and 50 per cent of the offspring will be free of the defective
gene. As long as the offspring are also tested, even carriers
can be bred from again as long as it is ensured that they
are only mated with a non-carrier cat. In this way, controlled
breeding programmes can be implemented so that important lines
can be retained within the gene pool.
tests are available and can carrier cats be detected?
a reliable test does exist for PK deficiency. It comprises
a DNA test that is performed on either a blood sample or cheek
swab. A genetic test is available at the Josephine Deubler Genetic Disease
Testing Laboratory at the University of Pennsylvania in the US, at the University of California, Davis and at Langford Veterinary Diagnostics, University of Bristol. Affected cats as well as carrier cats can be identified
with the test.
worry about PK deficiency?
deficiency is inherited and although predominately a problem
in the US it is being reported increasingly in cats throughout Australia, New Zealand and Europe,
including the UK.
Approximately 2500 cats have been tested at Pennsylvania since 1998, and around
15 per cent of those have been found to carry the defective
gene (personal communication, Giger U, 2005). A recent UK survey showed 36 per cent of Somali cats to be carriers.
described above, the clinical signs that develop can be
serious and life threatening.
initial clinical signs can be mild or go unnoticed, affected
cats may not be identified until after they have had large
numbers of offspring.
cats do not show any clinical signs at all. The disease
occurs when two carrier cats are mated with each other.
This is important because a large number of carrier cats
can arise in a population before PK deficiency is even noticed.
any genetic disease, by the time the disease becomes an
obvious problem within a population it is much more difficult
to control and involves a lot more expense and heartbreak.
The Somali Cat Club in the UK is very proactive in tackling the problem of pyruvate kinase deficiency. Following the recent UK survey the Governing Council of the Cat Fancy (GCCF) has changed its registration policies so that all breeding Somali cats need to be tested for it.
Updated November 2008