Jellyfish, Portuguese Man o’ War and Dogs at Florida Beaches

Florida dogs meet jellyfish and Portuguese man o’ war both in the water and, more often, washed up on the sand – and a stranded one can still sting. Many stings are painful rather than dangerous, but a dog that bites or licks one can get stung inside the mouth, and swelling there is a vet emergency. Keep your dog from sniffing, licking, biting or rolling on anything gelatinous or blue on a Florida beach.

What is washing up on Florida beaches

The one to know by sight is the Portuguese man o’ war. It looks like a blue or purple inflated bag on the sand, often with a crest along the top and a tangle of blue tentacles. It is not actually a jellyfish. NOAA describes it as a siphonophore, a colony of specialized organisms working together, and notes its tentacles typically reach about 30 feet and can reach 100 feet. Those tentacles are loaded with stinging cells, and UF/IFAS Extension describes the sting as particularly painful. Most important for dog owners, NOAA says a man o’ war may still sting you even weeks after it has washed ashore.

True jellyfish show up too. UF/IFAS Extension lists the moon jelly, sea nettle and cannonball jellyfish as locally common species whose stings are painful but generally less severe. Moon jellies are the big clear saucers with a four-leaf-clover pattern in the middle. Sea nettles have longer tentacles trailing behind the bell. Cannonballs are firm and round, and UF/IFAS notes that moon and cannonball jellies can leave thick masses on the beach for long periods.

Timing depends on wind and currents, because none of these animals can swim against them. The UF/IFAS Extension office in Escambia County notes that surface drifters such as the man o’ war arrive early in the year, with strandings documented as early as February, while sea nettles and moon jellies tend to come later in summer. Onshore winds are what push them onto the beach, which is why you can have a clean beach one day and a strand line full of blue bubbles the next.

Watch the purple flag

Florida beaches use a purple flag to warn of dangerous marine life. According to UF/IFAS Extension in Flagler County, a purple flag means dangerous marine life may be present, often jellyfish or man o’ war. It can fly alongside other flags, so check the whole pole when you arrive. If purple is up or you can see many animals stranded along the waterline, keep the dog on a short leash and away from the wet sand, and skip the swim that day. For the other animal that stings in the shallows, see Stingrays and Dogs.

Why dogs get stung where people do not

Dogs explore nose-first. A person steps around a blue blob; a dog sniffs it, licks it, picks it up or rolls on it. That puts stings on the nose, lips, tongue and inside of the mouth, as well as on paw pads and the thinly furred belly. Long-haired and double-coated dogs can also collect tentacle fragments in their coat, which keep stinging when the dog, or you, touches them later.

Tentacle pieces are hard to see, especially mixed into seaweed. Dogs that eat seaweed, pick up dead fish, mouth shells or roll on beach debris need extra supervision whenever jellyfish are around, and a beach that has been raked is not necessarily clear. Use a short leash when the wrack line contains seaweed, jellyfish, fish carcasses or fishing debris.

If your dog is stung

1. Move the dog away from the animal and the strand line so it does not get stung again.
2. Stop licking and rubbing. Keep the dog from licking the spot, pawing or rubbing its face, or rolling in the sand, which can drive tentacle fragments in further.
3. Do not touch tentacles with bare hands. For people, UF/IFAS Extension advises removing tentacles with tweezers, rinsing with salt water and soaking in hot water if available. For a dog, call your veterinarian for instructions before you try anything, especially if tentacles are in the mouth, around the eyes or embedded in thick fur.
4. Skip the home remedies unless your vet says otherwise. First aid varies by species, and the vinegar, ammonia, baking soda, fresh water and human medications that people reach for are not automatically right for a dog.
5. Call your vet even for a sting that seems minor, so you know what to watch for over the next few hours.

When a sting becomes an emergency

Go to an emergency vet if your dog has trouble breathing, swelling of the face, lips, tongue or throat, severe swelling anywhere, collapse, weakness, repeated vomiting or pain that seems extreme. A sting inside the mouth deserves a fast call even without those signs, because swelling there can affect breathing. Small dogs and dogs that actually ate part of an animal are the ones we would move fastest on. If you are unsure, go. A few hours of watching in a hotel room is a poor trade against a swollen airway.

For an emergency vet near you, see Pet Help (it covers some counties so far) or search for the nearest 24-hour animal hospital while you rinse.

Keep in mind that a day at the beach can stack up problems. A dog that has been swallowing seawater while chasing waves can develop saltwater poisoning, which also causes vomiting and weakness. Tell the vet everything the dog was doing, not just the sting.

Before you head to the beach

• Check the beach flags on arrival and look along the waterline and strand line before letting the dog near it.
• Keep the dog leashed and away from any stranded marine life, including pieces that look dried out.
• Avoid swimming during heavy jellyfish activity, and check long coats for tentacle fragments (wearing gloves, not bare hands) before the dog gets back in the car.
• Save the number for the nearest emergency vet to your beach before you go. Our Florida Wildlife Emergency Checklist for Pet Travelers lists what else to have ready.

For planning, see Best Pet-Friendly Beaches in Florida and, for the bigger animals in the same water, Sharks and Dogs at Florida Beaches. The simplest rule still covers most of it: if it washed out of the ocean, do not let the dog put it in its mouth.