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Dangerous Supplements

Your cat has a peculiar body system that seems almost (cover your cat's ears) deficient at times. He needs many vitamins and minerals that his body, unlike, say, a dog's, is unable to produce. Supplementing with vitamins seems like the way to go; how can giving him a heap of healthy vitamins be bad? In practice, however, vitamin over-supplementation can bring on a multitude of health problems.

Vitamin A

Vitamin A is a fat-soluble vitamin that comes in two forms, beta-carotene and retinol. Beta-carotene is mostly found in plant matter, and retinol is mostly found in animal matter. Curiously, cats can't convert beta-carotene to vitamin A as humans can; their only source of vitamin A is retinol.

Some places your cat will get vitamin A include liver, egg yolk, butter, fish liver oil and kidneys.

Because vitamin A is fat-soluble, it lingers in your pet's body for a long time, so it is easy for your cat be overdosed, causing hyper-vitaminosis A. When this illness occurs your pet's spine begins to harden, a painful condition that has the following symptoms:

  • Difficulty walking
  • Muscle degeneration
  • Pain in the legs and body
  • Stiff neck
  • Loss of appetite

The stiff neck is usually the first sign that something is wrong with your pet; you will notice that he has problems grooming himself. This condition must be treated immediately -- if it is left for too long, the spine will eventually harden permanently and he will be unable to move.

Vitamin D

Vitamin D is called the sunshine vitamin, and for good reason: animals usually absorb vitamin D by being out in the sun. The ultraviolet rays hit your cat's skin, and the oils there produce vitamin D that is then absorbed through the skin and transferred to the rest of the body, where it is stored until it is needed.

Vitamin D is a fat-soluble vitamin that comes in two other forms besides sunshine: ergocalciferol, which comes from plant matter, and cholecalciferol, which comes from animal matter. Besides sunlight, your cat will also get vitamin D from eating fish, liver, egg yolks and cod liver oil.

If your cat has too much vitamin D in his diet, he will contract hyper-vitaminosis D. This is an extremely dangerous condition involving the hardening of your pet's internal organs and blood vessels. Symptoms include:

  • Pain when touched
  • Decreased appetite
  • Increased water intake
  • Vomiting
  • Weight loss

This condition can kill your cat. It is a serious matter, and if you notice these signs you should take him to the veterinarian immediately.


Calcium is essential in bone growth and maintaining healthy, strong teeth; it is one of the most needed minerals in your pet's diet. Calcium works hand in hand with vitamin D and can't be absorbed without vitamin D in the diet. Sources of calcium include sardines (a cat favorite), green vegetables and milk products.

An excess of calcium in your cat's diet will result in painful bone deformities, bone spurs and calcium deposits. It can also cause problems with his production and absorption of phosphorus, zinc, iron and iodine. This condition can become even worse if your pet also has an excess of vitamin D.


This mineral is essential to the body for muscle and nerve function, as well as helping convert blood sugar into energy. Magnesium also helps the body break down several other vitamins and minerals.

Magnesium can be found in chicken breasts, tuna, sardines, shrimp and nuts.

An excess of magnesium can pave the way for a host of ailments, including the dreaded FLUTD (Feline Lower Urinary Tract Syndrome) and other urinary problems. Magnesium is rarely needed as a supplement; even though there are not many places your cat can naturally ingest magnesium, there is more than enough in the ash content of most pet foods.

Symptoms of FLUTD Include:

  • Bloody urine
  • Straining and inability to urinate
  • Depression
  • Loss of appetite
  • Vomiting
  • Dehydration

If your cat shows any of those signs, rush him to the veterinarian. FLUTD can be fatal if left untreated, and it is a painful and depressing illness for your pet to suffer through.


Your pet needs phosphorus because calcium is ineffectual without it, but your cat can easily get too much of it in his diet. Phosphorus is in all animal protein, so your cat gets a good dose of it simply by being a meat eater. Sources of phosphorus are meats, fish, egg yolks and whole grains.

An excess of phosphorus in your cat's diet can result in calcium deficiency, bone growth problems and convulsions. Watch for this substance in foods; phosphorus is also called calcium phytosphate, sodium phosphate and sodium pyrophosphate and is used as a food additive.

Preventing Vitamin and Mineral Excess

If the label on your pet food reads "balanced," that means your pet's diet has already been supplemented with vitamins and minerals. It is never wise to feed your cat supplements just because they are supposed to be good for him; too much of a good thing CAN be harmful at times. Check with your veterinarian before putting your cat on a supplementation diet, and do not feed your cat vitamin supplements and food supplements at the same time.