Heat destroys the enzyme responsible for cyanide production. Most cat foods are cooked at high temperatures.Blue Buffslo often puts flaxseed in their products and flaxseed causes cyanide poisoning. Please see my post on this. Two other companies I found puts yucca in their products and it is listed on the poison pet hotline. See my post on this. Additionally my nutrition vet said to stay away from food that has tricalcium phosphate or dicalcium phosphate in it. Purina and Royal Canin conducted research and found the phosphate picks up minerals and deposits them in the kidneys causing markers in the cats’ blood indicating kidney damage. Additionally I found research on sodium tripolyphosphates indicating that if most of the phosphorus is sourced from this it enters the bloodstream too fast and can then cause kidney damage from too high of a phosphorus level. I found all this and alerted companies and they are not changing their formulas. It is maddening!!! Additionally I try to find a cat food with a lower amount for phosphorus in it as once your kittens are fully grown they won’t need much. I am shooting for a dry matter basis of phosphorus of near 1 or a little less than 1 for my 2 year old cat. I think your cats need to go in right away. There are ER facilities in local animal shelters and call the ASPCA or Humane Society. They can all help you. Don’t wait. Your cats might need a slow drip of fluid to help flush out the toxins. Sending prayers!
The issue would be flax in the low temperature cooked foods.
How Much Ground Flaxseed Can Animals Safely Eat | Nutraceutical Alliance