The problem food is the one illustrated on this page as I understand it. It appears to be a high quality cat food but by all accounts it is causing serious neurological problems in the cats who have eaten it and the current assessment is that the cause is a thiamin deficiency. This is not first time that pet food manufacturers have produced cat food with such a deficiency. Vitamin B1 is very important to a domestic cat and if it’s missing in the diet it can have serious health consequences. There have been reports of cats dying in this instance and cats can become comatose unless they are given injections of thiamin and revert back to a balanced diet.