Thiamine deficiency

Thiamine (vitamin B1) deficiency causes a clinical syndrome in cats associated with vascular and neuronal damage.

It is due to an inadequate dietary intake of thiamine, a component of the B complex group of vitamins, relative to the body’s overall needs. This deficiency is more common in cats than dogs and is especially prevalent in raw-fish eaters. Thiamine deficiency may occur with an all-fish diet, since viscera of many freshwater and saltwater fish contain thiaminase. Storage may have an effect on thiamine levels. Thiamine in food, especially processed meats, is also destroyed by sulphites or sulphur dioxide used as a preservative. Thiamine is also destroyed by cooking cat food[1].

Thiamine is a co-enzyme in the oxidative metabolism for energy production in the central nervous system. Thiamine deficiency typically produces lesions (polioencephalomalacia) in the brainstem gray matter and more specifically in the vestibular, oculomotor and lateral geniculate nuclei and caudal colliculi. Focal, bilateral symmetric hemorrhages are present in affected areas.

There is some evidence to suggest that kittens may be more prone to this problem and exhibit signs such as diarrhoea which is unresponsive to most medications. Thiamine injections can be easily given to rule out this possibility in kittens.

Anorexia in a sick cat especially associated with polydipsia and polyuria or fluid diuresis may precipitate thiamine deficiency and complicate the primary illness.

Clinical signs include a significant neck flexion (ventroflexion or bending in a downward position), vestibular ataxia, dilated pupils (mydriasis) and seizures[2].

The diagnosis is largely based on clinical signs and history and exclusion of other causes of seizures. Baseline tests to include a complete blood count (CBC), biochemical profile, and urinalysis are recommended in all patients, although are most often within normal limits.

The typical bilaterally symmetrical nuclear lesions can be seen on MR imaging.

Treatment involves administering thiamine by injection for a several day to several week period, feed a proper well balanced diet and limit or discontinue raw-fish diet.

Prognosis is excellent if the disease is treated early and the diet is improved.



  1. ↑ Rand, J (2006) Problem-based feline medicine. Saunders Elsevier, Sydney
  2. ↑ Palus, V et al (2010) Thiamine deficiency in a cat: resolution of MRI abnormalitites following thiamine supplementation. JFMS 12:807-810


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