Iodine in Cats Functions and Deficiency Symptoms

Iodine is a lustrous purple-black colored halogen. This non-metallic element has about 37 known isotopes including the radioactive iodine often used to treat hyperthyroidism.

Iodine, like other minerals such as selenium, copper, iron, manganese, and zinc, is required in small amounts (trace minerals).

About 70-80% of iodine inside a cat’s body is concentrated in thyroid glands.


Although it occurs naturally in foods such as seaweeds (including Kombu kelp, Wakame, and Nori), codfish, shrimp, tuna, eggs, dairy products, among others. Most of these sources may not meet the recommended amount of required by cats.

Is iodine necessary for cats
Is iodine necessary for cats

Therefore, in most cat foods, it is added including through the use of iodized salt to meet the dietary requirements.

is iodine safe for cats

Yes. It is safe for felines. These pets need it to avoid deficiency symptoms. According to AAFCO 2015, the minimum recommended amount is 0.45mg and 0.15mg per 1000 kcal ME cat food for growth or reproduction and adult maintenance respectfully.

Alternatively, based on a dry mass basis, the required amounts are 1.8 mg/kg and 0.6mg/kg of cat food for growth or reproduction and adult maintenance respectfully with a maximum allowable amount being 9 mg/kg.[1]

If your feline friends depend on home-based diets, your vet will guide you on how to add iodized salt (sodium chloride) to meet this animal’s needs.

In the case of commercial cat foods, this mineral is supplemented using potassium iodide, calcium iodide or sodium iodide.


In these animals, it is needed to help make thyroid hormones, i.e., the thyroid glands utilize iodine in making thyroid hormones especially thyroxine (T4) and triiodothyronine (T3).

These hormones are vital controlling normal body metabolism, i.e., both anabolism (synthesis of complex molecules from small units using energy in form of ATP) or catabolism (the breakdown of complex molecules to smaller units to releases energy).

Also, thyroid hormones work synergistically with other hormones to help in growth and development, cell differentiation and proper functioning of their bodies.

Iodine deficiency in cats

Deficiencies are not common since most commercial diets have enough amount. However, digestive disorders and inappropriate diets may result in a deficiency whose symptoms include thyroid gland enlargement or hyperplasia.

Additionally, according to Canna-Pet, iodine deficiency is one of the causes of hypothyroidism in cats. Symptoms of feline hypothyroidism include alopecia, weight gain in geriatric felines, poor growth, lethargy, inactivity, behavioral changes, depression, infertility, among others.

Excess iodine in cats

Some of the symptoms associated with excessive amounts of this mineral in cats include excessive drooling, nasal discharge, and tearing as well as the presence of dandruff.

There are sources [1] linking excessive dietary iodine with hyperthyroidism. There is no conclusive research on this issue as there have been conflicting results with some supporting the idea while others do not.

However, as a treatment of hyperthyroidism, the use of ‘iodine restricted diets’ or ‘low iodine cat foods’ such as Hill’s® Prescription Diet® y/d™ Thyroid Care Dry or Hill’s Prescription Diet y/d Feline Thyroid Health wet canned food may be helpful.

This is because such foods will only help reduce the amount of this mineral available and consequently the amount of thyroid hormone. However, such diets will not treat some causes of hyperthyroidism.

Therefore, if such diets are used as a treatment for felines with hyperthyroidism, their application is more practical if you are considering them as a means of restricting this mineral and consequently thyroid hormone.

Can you use iodine on cats?

Yes, if you are looking for safe antiseptic for cats besides chlorhexidine gluconate and saline solution, you can use dilute povidone-iodine (Betadine) including for preoperative skin scrubbing among other uses.

Betadine is effective safe and it will help kill bacteria and prevent bacterial infections, help heal superficial cuts, burns, among other uses.

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