Iodine (I) is an essential trace mineral that is indispensable for the synthesis of thyroid hormones (T3 and T4). Thyroid hormones regulate basal metabolic rate, thermoregulation, growth-development and neurological functions. Iodine deficiency may lead to hypothyroidism, while excess intake may contribute to hyperthyroidism or paradoxical hypothyroidism. Hyperthyroidism in cats is the most common endocrine disease, and dietary iodine levels play a critical role in the management of this disease.
| Chemical Symbol | I |
| Resource Type | Trace Mineral (Essential) |
| Function | Thyroid Hormone Synthesis (T3, T4) |
| Dog Need | 1.0 mg/kg DM (AAFCO min.) |
| Cat Needs | 1.8 mg/kg DM (AAFCO min.) |
| Safe Upper Limit | Dog: 11 mg/kg DM, Cat: 9 mg/kg DM (NRC) |
| Common Resources | calcium iodate, potassium iodide, seaweed |
| Discussion Level | medium |
Iodine, It is an essential and critical trace mineral. It is indispensable for thyroid function. All quality foods must contain AAFCO/NRC. Iodine level is of particular importance in the management of hyperthyroidism in cats.
Why Added?
- Thyroid hormone: Single mineral substrate for T3 and T4 synthesis
- Metabolism: Regulates basal metabolic rate
- Growth-development: Critical for neurological and skeletal development in young animals
- Thermoregulation: Contributes to body temperature regulation
Feline Hyperthyroidism and Iodine Management
Hyperthyroidism in cats is the most common endocrine disease (~10% of older cats). Therapeutic iodine-restricted diets, such as Hill's y/d, use very low iodine levels (around 0.2 mg/kg DM) to help limit thyroid hormone production. Additional iodine sources (seaweed supplements, fish-based foods) should not be given to hyperthyroid cats. In dogs, excessive iodine intake may paradoxically lead to temporary hypothyroidism via the Wolff-Chaikoff effect.
Frequently Asked Questions
Is the iodine source in food important?
Calcium iodate and potassium iodide are standard and reliable sources. Seaweed is a natural source of iodine, but its iodine content may vary depending on the species and harvest. In hyperthyroid cats, the source and amount of iodine should be checked by the veterinarian.
Related VetKriter Tools
Bibliography
- NRC (National Research Council). (2006). Nutrient Requirements of Dogs and Cats. National Academies Press.
- Peterson, M.E. (2012). Hyperthyroidism in cats: What's causing this epidemic of thyroid disease and can we prevent it? Journal of Feline Medicine and Surgery, 14(11), 804-818.