(Poll Hereford calves)

Dd: Cardiac white muscle disease (nutritional myopathy, selenium deficiency)

Diagnosis

CWH is a congenital genetic disease with an autosomal recessive disease, presumed to involve defective structural protein(s) within the desmosomal complex.

Affected calves can be identified at birth by their distinctive woolly haircoat, which has also been described as 'fuzzy', 'wirey' and 'curly'. Some CWH calves have protruding eyes and keratoconjunctivitis ("pinkeye"). Cardiac arrhythmias are usually detectible

Death from heart failure occurs between birth and 12 weeks of age. Most calves with CWH die suddenly. Owners occasionally see an affected calf collapse and die, usually following exertion. If an affected calf is observed closely it may show signs of progressive heart failure before dying.

Clinical signs. and gross cardiac ventricular fibrosis, with or without mineralisation. Microscopic examination is necessary to accurately demonstrate the extent of the heart muscle changes.

CWH cases can be misdiagnosed as cases of selenium deficiency (cardiac white muscle disease, nutritional myopathy), particularly if the woolly haircoat is overlooked. Calves with CWH are not deficient in selenium.

Any woolly-coated Poll Hereford calf that dies during the first few months of life should have a postmortem examination to check for evidence of cardiomyopathy. It is not sufficient to attribute the death of a woolly-coated calf to CWH without postmortem confirmation of the cardiomyopathy.

Specimens required

1. Whole heart, eyes, liver, kidney and skeletal muscle (including diaphragm, tongue, psoas muscle).in buffered formalin.
2. Fresh liver and kidney for selenium estimation.
3. 2 x 10 ml of EDTA blood (1.5 mg EDTA/ml of blood) for DNA isolation (from affected calf, dam and sire). These DNA samples will be held pending development of a diagnostic DNA test (not yet available)
4. 1 x 10 ml lithium heparin blood for GSHPx.