Specific intake recommendations and standards for nutritional adequacy of commercial diets have reduced the risk for many essential nutrient deficiencies; however, thiamine deficiency remains an issue even in modern commercial diets.
Although reported in dogs and cats that receive complete and balanced dry diets, thiamine deficiency is largely seen in cats that eat predominantly home-cooked or canned diets (especially those labeled for intermittent and supplemental feeding only).
Compared with many other nutrients, thiamine tends to be heat labile and can be degraded with cooking. In addition, some diet ingredients contain thiaminases that can degrade the thiamine even without heat processing. Manufacturers typically add high enough amounts to the diet before cooking to compensate for expected losses; however, a recent study suggested that almost 1 in 6 canned cat diets may still contain inappropriately low amounts of thiamine.2
Thiamine deficiency, particularly in cats, often manifests with nonspecific signs of lethargy and anorexia followed by acute neurologic signs that include ataxia, seizures, cervical ventroflexion, and eventually death.
Related Article: Thiamine Deficiency
Diagnosis is classically based on clinical signs, suggestive symmetric brain lesions on MRI, measurement of blood thiamine or RBC transketolase activity, and response to thiamine supplementation. In the absence of imaging or measurement of thiamine status, thiamine deficiency can be easily confused with other diseases and may not receive appropriate treatment in a timely manner.
If the deficiency is identified early enough, many patients respond quickly and completely to thiamine supplementation and dietary change, although some may have lingering neurologic deficits.