Dog ate seaweed on the beach and other beach dangers

If your dog ate seaweed on the beach, phone your vet now, even if your dog seems fine. Seaweed that has dried out on the sand swells again when it soaks up fluid in the stomach, and a lump of it can block the gut. Beach seaweed is also salty, and it can hide rotting fish, crabs, fishing line and bacteria.

A strand or two of wet seaweed is far less risky than a mouthful of dry, crispy weed from the tideline. You often can't tell how much your dog swallowed, though, so let your vet decide whether it needs a check.

Is seaweed toxic to dogs

The seaweed itself isn't poisonous. Wild seaweed causes harm in other ways. It swells and blocks the gut, and its salt can upset or poison a dog. Anything that has died or tangled in the weed comes along too.

Plain, unsalted seaweed sold as food is a different thing, and dogs can eat seaweed like nori in small amounts.

Signs to watch for after a dog eats beach seaweed

Any one of these after a beach walk is a reason to call your vet straight away.

• Vomiting, or retching with nothing coming up
• Not wanting food
• A belly that looks swollen or feels tight, or a dog who stands hunched and can't settle
• Diarrhoea, or straining with no poo
• Tiredness, weakness or hiding away
• Heavy thirst, wobbling or trembling, which can mean too much salt

A blockage builds as the seaweed moves down the gut, so signs don't always show on the day, and that is why you should keep watching for the next couple of days even if your dog seems normal tonight.

Can seaweed kill a dog? It can. A blockage left untreated can damage or tear the gut wall, and the vomiting and dehydration that come with it can lead to shock. The sooner your dog is seen, the better its chances.

What to do if your dog ate seaweed on the beach

1. Get your dog away from the seaweed and take anything left in its mouth.
2. Work out roughly how much it ate, whether the seaweed was dry or wet, and when.
3. Phone your vet, or the out-of-hours vet if it's late. Tell them your dog's weight as well.
4. Don't make your dog sick unless the vet tells you to.
5. Offer fresh water in small amounts, and keep your dog quiet until you've spoken to the vet.

If you can't reach a vet, the Animal PoisonLine in the UK gives owners advice 24 hours a day on 01202 509000, and in the US the ASPCA Animal Poison Control Center is on (888) 426-4435. Both charge a fee. Ireland has no dedicated animal poisons line for owners, so your own vet or the nearest out-of-hours clinic is the number to keep in your phone.

What the vet will do

Your vet will feel your dog's belly and ask what was eaten. If a blockage is possible, an x-ray or ultrasound shows whether there is a mass of seaweed in the stomach or gut. Blood tests show dehydration and salt levels.

Your dog may go on a drip for dehydration and be watched while the seaweed passes. If it is stuck and won't move on, the vet removes it in surgery.

Why beach seaweed is different from seaweed in dog food

We make seaweed supplements for dogs, and our answer to beach seaweed is no. Weed on the beach has dried in sun and wind into hard, light strands that take up water again inside your dog. It is crusted with salt and may have been rotting for days. Some species, kelp above all, also hold very high levels of iodine.

We have worked with seaweed for 15 years, harvesting, drying and milling it, and the thing that stands out is how much water dried weed takes back. Soak a handful of dry strands and they swell well past their dry size and turn heavy and slippery. A dog's stomach does the same to a mouthful of tideline weed. Weed thrown up on the shore also starts to break down once it is out of the water, which is why we only use seaweed harvested from the sea.

Seaweed for dogs as a supplement is a different product. Every batch we make is tested. The seaweed in our Irish Kelp is harvested off the west coast of Ireland, dried at low temperature in a dehumidifier room and then milled into a fine powder that mixes through food. It is fed with a 2 g scoop by the dog's weight, and Canident is half to one 2 g scoop per 10 kg a day. A few grams of fine powder has no lump to swell.

Both packs say to start with a small amount and build up. Irish Kelp is not for dogs with any thyroid problem, because seaweed is a natural source of iodine, and a dog with a diagnosed thyroid condition needs the vet's OK before Canident too. None of that applies to a dog that has wolfed a pile of dry weed on the beach. That dog needs a phone call to the vet.

How to stop a dog eating seaweed at the beach

Seaweed smells of fish and salt, so scavengers find it hard to leave.

• Keep your dog on a lead along the tideline, where the weed piles up, and let it run on the wet sand by the water instead.
• Avoid the beach for a day or two after a storm, when fresh piles of weed and dead sea life wash in.
• Train a solid "leave it" and reward it well. Bring better treats than the beach has.
• Give your dog a job. A toy to carry or a ball thrown into shallow water keeps its nose off the sand.
• For a dog that won't stop, a well-fitted basket muzzle still lets it pant and drink.

Other dangers for dogs at the beach

Sea water

A few gulps of sea water often give a dog loose stools later that day. Drinking a lot of it can cause salt poisoning, with vomiting, great thirst, wobbling and in bad cases seizures. That is an emergency for the vet. Bring fresh water and a bowl and offer it often. Keep fetch in the surf short, because dogs swallow water with every retrieve.

Dead fish, crabs and starfish

Washed-up sea life can carry toxins as well as bacteria. In early 2018 dogs died in Norfolk and Suffolk after eating dead sea creatures on the beach, and the Eastern Inshore Fisheries and Conservation Authority traced it to paralytic shellfish poisoning from starfish. Stop your dog eating anything washed up, especially after storms.

Blue-green algae and sea foam

Blue-green algae are cyanobacteria that form scums and mats, mostly on warm, still fresh water such as lakes and ponds, and sometimes in brackish estuaries. Their toxins, such as microcystins, can kill a dog within hours, and there is no antidote. If your dog swims in or drinks from water with a green or brown scum, rinse it off with clean water, wearing gloves, and go to the vet at once.

Most sea foam is harmless. The exception is foam from a harmful algal bloom breaking down near the shore, which can carry the bloom's toxins. Keep your dog out of foam where there are bloom warnings or the water is discoloured.

Jellyfish

Dead jellyfish on the sand can still sting. A stung dog paws at its face and mouth and may drool or yelp. Rinse the area with sea water, not fresh water, and lift off any tentacles with a stick or a gloved hand. Facial swelling or trouble breathing is a vet emergency.

Fish hooks, line and sharp litter

Baited hooks smell like food. If your dog has swallowed a hook, or there is fishing line hanging from its mouth, don't pull it. Go to the vet. Cuts from glass and sharp shells on a pad need rinsing with clean water, and deep or heavily bleeding cuts need stitches.

Sand

Dogs swallow sand when they dig, or chase a sandy ball over and over. A lot of it can settle in the gut as a heavy plug, called sand impaction. The signs match a seaweed blockage, so the same rule applies. Use a toy that floats in the water rather than one thrown along dry sand.

Heatstroke

Exercise, not a hot car, is what tips most dogs over. In a UK study of dogs under veterinary care, exercise triggered 74% of heat-related illness, far more than hot cars (Hall, Carter and O'Neill, 2020, Animals). Go early or late on hot days and take shade and water. Stop the games before your dog is flagging.

If your dog collapses, pants hard and can't settle, or seems confused, cool it before you drive to the vet. The Royal Veterinary College's advice is "cool first, transport second", with any water that is cooler than the dog. Cold water is better than lukewarm, and a conscious dog can stand in the sea, a stream or a bath. Keep cooling on the way with the windows open or the air conditioning on.

Waves and currents

Strong swimmers tire too, and a dog chasing a ball out to sea may not notice a current. Throw short and watch your dog the whole time it is in the water. On rough days, keep it on the beach. A dog life jacket with a handle helps in deep water or from a boat.

Questions owners ask

Can dogs eat seaweed from the beach?

No. Dried beach seaweed can swell and block the gut, and it is salty and often rotting. If your dog has eaten some, phone your vet.

How long after eating seaweed will a dog get sick?

There is no fixed time. Vomiting can start within hours, but a blockage can take a day or two to show. Watch your dog closely for at least two days and call the vet at the first sign.

Is sea foam dangerous to dogs?

Usually not. Foam near an algal bloom can carry toxins, so keep your dog out of it where there are warnings or the water looks off-colour.

References

• Hall EJ, Carter AJ, O'Neill DG (2020). Dogs don't die just in hot cars. Exertional heat-related illness (heatstroke) is a greater threat to UK dogs. Animals 10(8):1324.
• Royal Veterinary College, VetCompass. The RVC urges owners of hot dogs to "cool first, transport second".
• Eastern Inshore Fisheries and Conservation Authority (2018). Reports of dog illnesses on Norfolk beaches (paralytic shellfish poisoning).
• Backer LC et al. (2013). Canine cyanotoxin poisonings in the United States (1920s to 2012). Toxins 5(9):1597-1628.
• NOAA National Ocean Service. Is sea foam harmful?