Seaweed (kelp) is used in pet foods as a marine ingredient that provides iodine, minerals and antioxidant compounds. Species such as Ascophyllum nodosum are also known for their potential role in reducing dental plaque. Seaweeds naturally contain iodine, iron, calcium, magnesium and zinc together with bioactive polysaccharides such as fucoidan and laminarin. However, their high iodine content requires caution in animals with thyroid disease.
| Common Types | Ascophyllum nodosum, Fucus vesiculosus |
| Resource Type | Sea Plant (Algae) |
| Function | Iodine / Mineral / Antioxidant / Dental Health |
| Iodine Content | 700-1200 µg/g (varies depending on species) |
| Dog Iodine Needs | 1.0 mg/kg KM (AAFCO min.) |
| Cat Iodine Need | 1.8 mg/kg DM (AAFCO min.) |
| Iodine Upper Limit | Dog: 11 mg/kg DM, Cat: 9 mg/kg DM (NRC) |
| Discussion Level | medium |
Seaweed is a useful natural mineral source, but it should be dosed carefully because of its iodine content. Its use should be reconsidered in cats at risk of hyperthyroidism and in animals with known thyroid disease.
Why Added?
- Natural source of iodine: Provides essential minerals for thyroid function
- Dental health: A. nodosum Reduces dental plaque and tartar formation
- Antioxidant: Fucoidan and polyphenols reduce oxidative stress
- Mineral richness: Iron, calcium, magnesium, zinc in natural form
Thyroid Function and Iodine Toxicity
The high iodine content of seaweed directly affects thyroid function. Hyperthyroidism is common in cats, and excessive iodine intake may worsen the condition. In dogs, excessive iodine exposure can also disrupt normal thyroid regulation. If extra seaweed is supplemented, total iodine intake should remain below NRC upper limits. Veterinary supervision is essential for animals with thyroid disease.
Frequently Asked Questions
Is seaweed in food safe for cats?
The amount of seaweed used in food formulations is generally within safe limits. However, additional supplements should not be given and an iodine-restricted diet should be applied in cats diagnosed with hyperthyroidism. In case of doubt, a veterinarian should be consulted.
Related VetKriter Tools
Bibliography
- NRC (National Research Council). (2006). Nutrient Requirements of Dogs and Cats. National Academies Press.
- AAFCO (Association of American Feed Control Officials). (2024). Official Publication.
- Gawor, J.P. et al. (2018). Effect of Ascophyllum nodosum on dental plaque and calculus in dogs. Veterinary World, 11(10), 1478-1486.