Thiamine (Vitamin B1) deficiency in cats 

© Rand, J (2006) Problem-based feline medicine. Saunders Elsevier, Sydney

Thiamine deficiency is a clinical syndrome associated with vascular injury (pertaining to vessels) and nerve damage caused by vitamin B₁ deficiency. 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 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. Focal, bilateral symmetric haemorrhages are present in affected areas.

There is some evidence to suggest that kittens may be more prone to this problem and exhibit symptoms 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. 

Symptoms

Rigid ventroflexion (bending in a downward position) of the neck
Muscle weakness, chronic diarrhoea
Ataxia (wobbly walking)
Seizures
Fixed, dilated pupils
Paralysis of the muscles around the eye

Diagnosis

The diagnosis is largely based on clinical signs and history. 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.

Screening chest and abdominal radiographs (x-rays) are an important part of any baseline workup, especially to rule out other disorders.

Treatment

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

Home Care

Administer all medication and feed a well balanced diet as directed by your veterinarian. Contact your veterinarian at once if your pet is not responding to therapy or is getting worse. Prognosis is excellent if the disease is treated early and the diet is improved.