Why Is Fish Dangerous to Cats?

by Karel Carnohan DVM

There are very few cats who don’t like fish. So, as a staple diet, why is fish dangerous to cats? Fish contains an enzyme called Thiaminase. This enzyme breaks down Thiamine, an essential vitamin also known as B-1.  If cats are fed mainly fish, either as tuna or in pet food that is not supplemented with Thiamine, they can become very sick. Vitamin B-1/Thiamine is essential for neural health…. it feeds and protects neurons.

If a cat is thiamine deficient, it will develop neurological symptoms and eventually die if its diet is not corrected. Fortunately, cats can recover from thiamine deficiency if they get proper care and a well-balanced diet.

Vitamin B-1/Thiamine is essential for neural health… Click To Tweet

Recently, several pet food companies have recalled their cat food because it was deficient in Thiamine (most recently, Diamond Pet Food issued a recall).  Pet food companies must add Thiamine to their fish formulas to compensate for the enzyme and ensure cats get enough Thiamine. It is likely that their food was tested and found to have inadequate levels.  I like to give the pet food companies credit for doing the right thing by recalling their foods: it shows they are testing and following through.

Along those lines, a pet peeve of mine is pet food companies that market “cat food,” mostly canned food, that is “all tuna” and “100% Natural Chicken.”  If shoppers are not careful and aware, they often assume this is a complete diet for their cat. IT IS NOT! Many companies do not make it clear that this is designed to be a TREAT and not to be the cat’s main diet. The words to look for on the label should indicate compliance with the guidelines of the American Association of Feed Control Officials (AAFCO). The label should say: “FORMULATED IN ACCORDANCE TO AAFCO GUIDELINES TO BE A COMPLETE AND BALANCED DIET,” or some variation on that statement. Even better, a pet food company will test its food via feeding trials to ensure its products are healthy. For growing kittens, it is best to find a diet formulated for their age and that should be noted in the AAFCO statement.

AAFCO guidelines aren’t perfect and are in need of updating, but they are the best we have at the moment. So please read labels and be aware there are many companies jumping on the pet food band wagon who neither have the expertise nor the resources to ensure their products  are healthy and complete for your pet. Good nutrition is important for your cat’s long term health.

After a long career in finance, Dr. Carnohan  followed her heart. She returned to school and in 2005,  graduated from the Kansas State College of Veterinary Medicine at the tender age of 50. She bought the Cat Care Clinic of Asheville in August 2013, fulfilling her dream of owning her own practice and spending her time with the cats she loves.

photo credit: ♥❤♥ Sweet Lucy ♥❤♥ via photopin (license)

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