Can Dogs Eat Seaweed? More On Sea Kelp, The Best Iodine Supplement For Dogs


Let's start with the answer first- yes they can with a “but”. This doesn’t mean that you can feed your dog any kind of seaweed under the sun. Not all seaweed is edible, especially not those that are washed up on the beach.

As with all things, moderation is the key. Although seaweed is not exactly dogs’ natural diet, it contains some nutrients that are beneficial for their health.

A careful balancing act is required when dealing with this supplementary food. Read on to know the intricacies of dealing with seaweed supplements.

What is seaweed good for?

Seaweed is a nutritionally complete source of food. Apart from fiber, it contains over 60 mineral elements but more notably for these nutrients:

  •       Iron
  •       Zinc
  •       Iodine
  •       Calcium
  •       Selenium
  •       Potassium
  •       Magnesium
  •       Omega-3 fatty acids
  •   Vitamins A, B, C, D and E

Generally, small portions of seaweed intake have been shown to improve coat health, joint health and metabolic health. The health benefits depend on the type of seaweed, as each species will have different percentages of nutrient content. Nonetheless, it is touted mainly for its iodine content.

What is iodine good for?

Iodine is an essential nutrient for thyroid health. The function of the thyroid gland is mainly to regulate metabolism. Low thyroid function can cause other health problems including obesity, allergies, skin conditions and even seizures.

Too much or too little iodine can cause various health problems such as goiter, hyperthyroidism and hypothyroidism, infertility and even cognitive dysfunction.

Deficiency of iodine in dogs can be caused by an all-meat diet. Signs of deficiency include excessive hair loss, a dry sparse coat, weight gain and enlargement of the thyroid gland (goiter).

For growing puppies, iodine is even more essential as it is needed for the formation of thyroid hormones (thyroxine and tri-iodothyronine). Though only very small amounts are needed, the absence or a shortage of iodine in puppies’ diets can inevitably cause problems in their growth and development.

Is iodine toxic to dogs?

No but large doses over a period of time will cause health problems, such as thyroid gland inflammation, thyroid cancer and hyperthyroidism.

Too much of it can be toxic. Signs of iodine poisoning include excessive salivation, nasal discharge, flaky dry skin and excessive tear discharge.

Types of seaweed

Seaweeds are basically a group of marine algae. There are many types of seaweed; some are edible and some are not. So, just because you find some seaweed washed up on the beach, it does not mean it is safe for you or your dog to go noshing it.

These saltwater algae come in a variety of sizes, shapes and colours. Other than the usual green, there are red, brown and black seaweeds.

This colour has a direct relationship with how much light seaweed absorbs via photosynthesis, which decides how close to the ocean’s surface it grows. Each species also has its own characteristics, and varying percentages of different nutrients.

The types that we are accustomed to and that we humans consume are wakame, nori, kombu, aonori, hiziki, mozuku, sea grapes, dulse, irish moss, winged kelp and sea moss. The type that is commonly made into supplements for dogs are kelp.

Unlike land plants, seaweed collects nutrients through their leaves from the abundant resources in circulating seawater. If the ocean where they grow is polluted, the seaweed stationed there will also absorb the pollutants in the water.

Is seaweed good or bad for dogs?

Only the right type of seaweed is good, in the correct form and in moderate amounts.

The right type

Fresh seaweed has a high salt content, especially sea grapes which have cute grape-like leaves that pop in your mouth. Any food that has high amounts of salt is not good for pooch.

The type of seaweed that is usually used for making dog supplements is sea kelp. This is safe for consumption, but you should buy from a reputable, trustworthy brand.

The correct form

Some owners like to give their pets seaweed as a snack. This is fine as long as the snack is not salted or seasoned. Seaweed snacks made for humans are usually highly flavoured. Therefore, it may not be a good idea to give dogs seaweed snacks that are meant for humans.

Some human seaweed snacks are unflavoured or unseasoned. These are fine. However, if these come in a dry paper-thin form, they might not be so suitable for dogs.

Our canine pals do not chew like we do. A bite-sized seaweed slice might get stuck in the dog’s throat. Fido probably won’t choke to death but this will cause it a certain amount of discomfort.

Moderate amounts

Do remember that seaweed has a high iodine content. Too much of anything is always a bad thing. The same goes with iodine and whatever else the snack might contain.

We usually do not know where the seaweed is obtained from. The source is usually not mentioned on the packaging. That is where the risk lies. If the source is polluted, the seaweed may contain trace amounts of arsenic or mercury. Thus the wisdom in practicing moderation.

Seaweed is also very high in fibre. Too much fibre is also bad for your dog. Keep in mind he is not a herbivore.

Can dogs eat wild or dried seaweed?

Definitely not! As mentioned earlier, not all seaweed is edible. Dried wild seaweed found on the beach is the most dangerous.

Wild seaweed dries out due to exposure to the sun and heat, it shrinks to a fraction of its original size. A greedy dog might wolf down large amounts of it.

When ingested, these dry chunks of seaweed will absorb fluid in the dog’s stomach and intestine, and expand to more than double of its dried size. This can cause blockages in the digestive tract and become fatal for the dog.

If you suspect your dog has eaten wild dried seaweed, quickly bring it to the veterinarian. Its condition can worsen rapidly in mere hours from bad to close to death.

How seaweed can help dogs with thyroid disease?

First of all, iodine or seaweed supplementation is only advisable if the cause of the thyroid disease is iodine deficiency. What are the types of thyroid diseases?


Hypothyroidism occurs when your dog is not secreting enough of the thyroid hormones, causing your dog’s metabolism to slow. In 95 percent of cases, it is caused by destruction of the thyroid gland resulting from lymphocytic thyroiditis or idiopathic atrophy of the thyroid gland.


This is the opposite situation where there is too much of the thyroid hormone in the dog’s system. In this instance, iodine supplementation will be out of the question.


It can be caused by iodine deficiency, eating substances that affect thyroid function, having too much iodine in a diet, or inherited defects that affect the synthesis of thyroid hormones. Iodine supplementation makes sense only if the cause of goiter is iodine deficiency.  

How much seaweed can dogs eat?

According to an article in the Innovative Veterinary Care journal (IVC journal), kelp is the best type of seaweed for dogs. The most recommended species of kelp is Ascophyllum nodosum or A. nodosum.

It is a brown Fucus seaweed growing in the cold waters close to the Arctic tidal zones. This species is the most commonly harvested for animal nutrition, mainly because of its bulk and its purity from contaminants.

Kelp should make up only a small portion (about 0.25%) of the total dry food of a dog if the iodine content is at 750ppm per kelp serving. Other than iodine, selenium is another valuable nutrient derived from kelp.

In animal studies, kelp has been found to protect against the mammary glands from the effects of a carcinogen called  dimethylbenz[a]anthracene (DMBA). Reports from a number of clinical practices also show kelp to benefit cancer patients. Holistic practitioners claim that kelp supports the immune system.

One practitioner shared that a mauled dog’s coat grew back after a small amount of kelp was added to the dog’s diet. Its fur began growing back darker and thicker within two weeks.

Seaweed supplements for dogs

The best type of supplement is wholistic sea kelp. This means pure kelp that is harvested and processed in Northwest Iceland, one of the most pristine environments found worldwide and is certified organic by QAI and TUN.

QAI (Quality Assurance International) is a leader in organic certification services. Products certified by QAI have been verified to meet strict standards for organic integrity.

TUN is short for Vottunarstofan Tύn, an independent conformity assessment body, specialising in the inspection and certification of sustainable practices in agriculture, fisheries and related processing and trading activities. TUN is a member of the International Federation of Organic Agriculture Movements.

Pet Cubes’ Sea Kelp is made from Ascophyllum nodosum. This product is QAI and TUN certified organic based on its Arctic environment and also on its processing techniques that maintain its unusually high concentrations of minerals.  

Considerations when giving kelp supplements to dogs

Do NOT give kelp to:

  • nursing puppies when the mother dog is already given the supplement
  • dogs that are already on thyroid medication

Here are a few guidelines to ensure that you do not “overdose” your pet on iodine:

  1. Never exceed the prescribed dosage on the product label.
  2. Always check with your vet first before giving seaweed as a regular supplement.
  3. If you feed your dog cereal-based kibble, do not supplement with sea kelp or other forms of iodine more than three times per week. (These foods are usually fortified with high doses of iodine.)
  4. If you feed your dog a home cooked or raw diet, you can supplement with iodine but do number 1 and 2 first.


All in all, seaweed and kelp are proving to be a powerful and useful supplement for a number of health benefits. It is safe for dogs to eat seaweed in most cases except those where an excess of iodine is not advisable.