Is seaweed safe for dogs?

Seaweed dried by the sun at the tide line shrinks and becomes crunchy. Once swallowed, it absorbs water and can expand several times in size, forming a mass that blocks the stomach or intestines. Vets in coastal areas of the UK and Ireland see this regularly.

Washed-up seaweed can also hide fish hooks, jellyfish, dead marine animals and algae toxins, and it is very salty.

After eating dried seaweed, a dog may seem fine for several hours. As the seaweed absorbs water from the stomach and from drinking, the mass grows. Vomiting, drinking heavily, a swollen or painful belly, restlessness and loss of appetite may follow. Salt from the seaweed can also cause intense thirst and, in large amounts, tremors.

Plain nori sheets, the kind used to wrap sushi, are safe in small pieces. A strip the size of a stamp is plenty for a small dog. Avoid seasoned seaweed snacks, which are coated with oil, salt and sometimes sesame or chili, and sushi itself, which may contain raw fish, rice vinegar, wasabi or avocado.

Kelp powders are marketed for dogs as a source of iodine and minerals. Too much iodine can upset thyroid function. Only add kelp supplements if your vet recommends them, and stick to the dose they suggest.

Bring your own water and treats to the beach so your dog is less tempted to scavenge. A dog that picks at the tide line is best kept on a long line. Rinse your dog with fresh water after a swim to remove salt.