Ultimate Dog

By Luna Lupus - Reading Time: 9 minutes
kelp for dogs

Kelp for Dogs: The Role and Safety of Iodine Supplementation

When thinking about your dog's diet, ‘seaweed’ probably isn't one of the words that come to mind. Seeing as dogs aren't marine animals, how can we explain adding seaweed into their diets? Kelp, one of the most prevalent types of seaweed, is marketed as a necessary supplement for dogs due to the iodine it contains. 

But isn't iodine related to thyroid issues? How can a dog owner know if this supplement is safe when the internet is a pool of conflicting information? This article will take a closer look at the currently available credible information on kelp and iodine and the role they play in preventing (or managing) thyroid diseases. This article aims to lessen your confusion and help you make safe dietary choices for your dog. 

Seaweed for Dogs 

Think of seaweeds as “super plants” – plants that are much higher in nutrients than land plants. They have to be consumed in much smaller quantities than land plants, precisely because of their high nutrient concentration. Seaweeds absorb nutrients through their leaves from the ocean water that surrounds them. In comparison, land plants can only absorb nutrients from the soil in which they grow through their roots. 

As one article puts it: “Ocean water is literally the lifeblood of the planet, containing all essential nutrients in similar ratios to those in the mammalian bloodstream.” This means that with the consumption of seaweeds, our dogs receive countless crucial nutrients essential for their health. The most notable of these nutrients is a mineral called iodine. 

Iodine for Dogs – Why and How Much

Iodine is essential for the proper functioning of the thyroid gland, which is the most important endocrine gland, second only to the pituitary gland. The thyroid regulates the body's metabolism. It produces two significant hormones, T3 and T4, which affect most of the body's functions (heart rate, body temperature, quality of fur, brain development, and more). Iodine itself is a component of these two hormones. Without iodine, the thyroid cannot produce enough T3 and T4, leading to a hormonal imbalance and numerous health issues. In a dog's diet, iodine is more than just recommended – it is crucial. 

The most important thing about iodine for dogs is knowing the correct amount. Both too little and too much iodine leads to health complications. There are several sources out there recommending different amounts of iodine, and it can feel frustrating for dog owners not to know with certainty what the facts are.

Currently, the most credible information comes from AAFCO (The Association of American Feed Control Officials) and FEDIAF (European Pet Food Industry Federation), which recommend a maximum of 11mg of iodine per kilogram of dry matter in dog food. This is a very small amount and one that is hard to figure out for dog owners alone, so it can be easily overdone, however unintentionally.

What we feed our dogs daily plays a significant role in their iodine intake. If your dog eats food that is entirely prepared at home (raw or cooked), it's necessary to add an iodine supplement to their meals, as the amount of iodine in the meats, grains, and vegetables alone is not reliable. With a homemade diet, you have more control over your dog's iodine levels. 

It's harder to determine the amount of iodine your dog is getting on a commercial diet. Every dog owner wants to believe that buying dog food labeled as “complete” means we're giving our dogs all necessary nutrients in the appropriate amounts. Unfortunately, this is not always the case. Many commercial pet foods exceed the recommended daily iodine limit or skip the iodine altogether. 

You can determine whether your dog's food already contains iodine by checking the ingredients list. All ingredients in the dog food must be listed on the label. You can recognize an iodine supplement under these names: iodized salt, sea salt, sodium iodide/iodate, potassium iodide/iodate, and calcium iodide/iodate. Some labels may also directly list kelp or algae. Keep in mind that dog foods with fish and other seafood are naturally higher in iodine. 

The vast majority of dog food brands don't list the actual amount of iodine added, with very few exceptions. Some brands may be open to sharing the exact information with you if you reach out to them. Since there is no sure way of knowing how much iodine our dogs are already getting in their commercial dog food, if there are any ingredients indicating added iodine, we have to assume that they're most likely getting enough of it. 

Therefore, choosing the right food for your dog's age and stage is very important; their nutritional requirements change as they age, and so should your choice of commercial dog food. Gravitate towards dog food brands that are transparent in their labels and don't make it rocket science to figure out whether or not their product contains iodine.

Kelp for Dogs With Thyroid Problems – Yes or No? 

The short answer to this question is no. In most cases, it's best to leave kelp out of the equation if your dog has thyroid issues. Knowing what we know about iodine and thyroid function, it may seem like the next natural step to choose kelp as a supplement for dogs with thyroid issues – but in reality, we can cause damage to our dog's health and longevity, however good our intentions.

The most common thyroid disease in dogs is hypothyroidism. It happens when the thyroid is not active enough, and the metabolism becomes too slow. (In contrast, hyperthyroidism happens when the thyroid is overactive and the metabolism is too fast. This condition is very rare in dogs – when it does occur, it's mainly caused by thyroid cancer). Signs of hypothyroidism include weight gain, slower heart rate, changes in skin pigmentation, changes in the coat (dryness, shedding), feeling cold (seeking sources of heat), lethargy, and excessive tiredness (not wanting to exercise).

In some cases, the skin on the dog's face can thicken and give them a swollen and puffy look. Intact males and females can experience infertility, with the females also experiencing a lack of heats or having miscarriages. 80% of hypothyroidism cases are genetic and are NOT related to an iodine deficiency! They are a result of an autoimmune condition called thyroiditis. 98% of dogs with hypothyroidism are treated with a thyroid hormone replacement, which the dog receives for the rest of his life. 

Putting a dog with genetic hypothyroidism on an iodine supplement, such as kelp, is a very risky move. First, the dog is already receiving the necessary hormone replacement, and adding kelp into the mix can disrupt the medication. Second, if the hypothyroidism is not caused by an iodine deficiency, it's safe to assume that the dog is already getting a certain amount of iodine in his regular diet – adding kelp on top of that can lead to excessive iodine consumption, which would disbalance the thyroid's hormone production even more. 

Health Benefits of Kelp 

It's important to understand that the information above about the incompatibility of kelp with autoimmune thyroiditis does not mean that kelp doesn't have a place in canine nutrition. Kelp contains countless nutrients and has the potential to balance dietary deficiencies in malnourished dogs. Thanks to selenium, vitamin E, and the polysaccharides it contains, kelp can do wonders for the canine immune system. 

It can aid dogs in recovering from various conditions that impact their fur, skin, and weight. Some dogs still experience iodine deficiency due to eating food that is low in iodine, and kelp can be a helpful supplement in those cases. Additionally, animal research has shown that seaweed has anti-tumor properties and can prevent certain types of cancers, especially mammary cancer (which is very prevalent in un-spayed female dogs). 

How To Supplement Kelp Safely 

The crucial thing about supplementing kelp is the right dosage; too much kelp can be harmful to your dog's health, but the right amount can have many benefits. Different kelp products vary in how much iodine they contain, so it's critical that you closely follow the dosing instructions on the label. As mentioned before, dogs who eat commercial pet food already receive a certain amount of iodine in their diet, so take that into consideration. It's important to determine your dog's daily iodine intake before you add kelp supplement for dogs. 

Look for organic kelp (ocean pollution plays a factor in the quality of seaweed) and one that is manufactured specifically for dogs, as kelp sourced for human consumption will not have the correct dosage guidelines you need for your dog. If your dog is on any medication, you must consult with your veterinarian before supplementing with kelp! If you have questions or doubts about the dosage, contact an experienced canine nutritionist or a holistic veterinarian before making any changes in your dog's diet. 

Final Thoughts on Kelp for Dogs

Seaweed is a vital part of canine nutrition, but ever since pet food became a massive business industry, our dogs' nourishment became a complicated and confusing topic. Kelp is an excellent iodine supplement for dogs who don't have prior thyroid issues. Before we start supplementing, we have to get a general idea of how much iodine our dog is already getting through his daily meals. For those making their dog's food at home, this is an easier task than for those who buy commercial pet food. 

Pet food brands are not always transparent in their ingredient labels, which is confusing for owners who wish to determine the iodine amount in their pet's food. Your best bet is to choose a brand that is transparent with its label and isn't putting an excess of iodine in the dog food. After that, you can determine whether your dog needs an additional iodine supplement, such as kelp. Remember that kelp directly affects the thyroid gland, which has a strong influence over the whole body, so it's important to make informed decisions rather than experimental. 


Dodds, J. W., & Laverdure, D. (2011). The Canine Thyroid Epidemic: Answers You Need For Your Dog. Wenatchee, WA. Dogwise Publishing.

Lewter, Marjorie. Wolf, Bill. “Seaweeds for Animal Health.” Innovative Veterinary Care, 20/09/2017. 

Teas, Jane. Harbison, Margaret. Rebecca, Gelman. “Dietary Seaweed (Laminaria) and Mammary Carcinogenesis in Rats.” AACR, 07/1984. 

Williams, Krista. Ward, Ernest. “Hypothyroidism in Dogs.” 

Kritchevsky, Janice. Peterson, Mark. “Disorders of the Thyroid Gland in Dogs.” MSD Veterinary Manual, 06/2018. 

Teas, Jane. Pino, Sam. Critchley, Alan. Braverman, Lewis. “Variability of Iodine Content in Common Commercially Available Edible Seaweeds.” ResearchGate, 11/2004. 

Reading Labels.” AAFCO, 2012. 

Decoding Pet Food Labels.” Oromocto Veterinary Hospital. 

AAFCO Methods of Substantiating Nutritional Adequacy of Dog and Cat Foods.” AAFCO, 2014.

Luna Lupus

Luna’s passion for learning about canine psychology and behavior began when she adopted a severely reactive puppy from a local shelter. She is now a big advocate for positive reinforcement and compassionate training. As a writer, she strives to spotlight the topics that fly under the radar and be the voice for all who cannot speak for themselves.

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