Certain types of seaweed can be a nutritious addition to your dog's diet, though only in moderation. Seaweed is an excellent source of vitamins and minerals, including iodine, iron, calcium, magnesium, and omega-3 fatty acids. It also contains antioxidants, which can help support your dog's immune system.
Just remember that too much seaweed can cause iodine toxicity, which in turn can lead to hyperthyroidism (swelling in the gland under the jaw or neck area). And keep in mind that certain types of seaweed ,such as hijiki, contain arsenic, which could be harmful to your dog if they eat it regularly or in large amounts.
In general, you should only feed your dog seaweed as an occasional treat.
Also, you should only give them plain seaweed that's completely unseasoned. Soy sauce, for example, can make your dog extremely ill due to its high sodium content. And while seaweed itself can be safe to eat, that doesn't mean you should attempt to turn your pup into a sushi connoisseur; raw fish can contain illness-causing bacteria.
As always, before introducing a new food item into your pet's diet, consult your veterinarian first! If your dog eats seaweed (or any food) and shows signs of illness such as lethargy, diarrhoea, or vomiting, contact your veterinarian immediately. If your pet requires veterinary care due to something they ate, dog insurance can help cover the cost of treatment.