Published in Downeast Dog News
We’re hearing a lot about red tide this year, harmful algal blooms in the Gulf of Maine that cause state officials to close shellfish flats all along the coast. And because of June’s rainfall, several beaches were closed or under advisories for several days because of high levels of bacteria in stormwater runoff. But it turns out that while those conditions carry some minor risks for dogs that play on beaches and in the surf, the real danger is algae floating in freshwater lakes and ponds.
“Red tide” is a term that broadly covers many different kinds of algae with different toxicity levels. In some places around the world, toxic algae can be highly concentrated in seawater and may become airborne in surf spray, poisoning people and animals, including dogs and anything else that breathes along the shore.
News accounts from Florida state that the first reported cases of red tide toxins in dogs of the United States were in 2003 on the Gulf Coast, during a toxic algal bloom that became airborne. So, if you take your dog on a coastal trip, be sure to gather information about the type of red tide that may be found at that area.
The red tide found in Maine—which is actually brown—is not very concentrated, and has never been reported as airborne, according to Michael Sieracki, a senior research scientist at the Bigelow Laboratory for Ocean Sciences in Boothbay Harbor. Rather, the danger comes primarily from eating shellfish that have stored up the toxins after they consumed lots and lots of the algae.
While this year’s algal bloom is at “unprecedented levels,” according to Sieracki, it is still not so concentrated that it might harm dogs or people who are simply exposed to seawater. However, Sieracki does caution against letting dogs eat shellfish that might be found around the beach, because it may be contaminated.
Keri Lindberg of Maine Healthy Beaches, a state-run program that monitors water quality on Maine’s ocean beaches, agrees, and adds that even non-red-tide shellfish, especially uncooked—just the way our dogs prefer them—can also harbor dangerous bacteria that can sicken a dog. But she said that dogs are unlikely to get sick from algae unless they “ingest a lot of water” that is particularly contaminated.
Dr. Jennifer Roberts, a veterinarian at Maine Veterinary Referral Center in Scarborough, said that she has not heard of red tide as a problem for animals in Maine, and has not heard much about blue-green algae causing illness in dogs here, but it can be “very toxic,” often particularly hurting a dog’s liver. Roberts urged dog owners whose pets develop gastrointestinal distress to tell their vets not only whether the dog likes to chase the neighborhood squirrels or knock over trash cans, but also if the dog swims in the local ponds. This
information may help a vet identify blue-green algae toxicity as a possible cause of illness.
Dogs have died from blue-green algae poisoning in Lake Champlain in Vermont, which has led to periodic warnings from state health officials there. New Hampshire tests its lakes and issues blue-green algae warnings that mention potential dangers for pets and humans in areas with high levels of contaminants. Maine does track algal blooms, and just last year began tracking their toxicity, but at this time, the state does not issue warnings, according to Roy Bouchard, a biologist with the Maine Department of Environmental Protection’s (DEP) Lake Assessment Program.
Bouchard said that toxicity is “something nobody has a real good handle on yet,” and that states that do issue warnings are being “very conservative.” Because blooms can be nontoxic one day and toxic the next, it can be hard to keep track; lab tests require days or weeks to return results. As a result, the warnings are often based on visual observations from which experts draw the conclusion that the conditions make toxicity possible.
Between 38 and 54 lakes across the state have algal blooms “commonly” or “frequently,” according to the Bureau of Land and Water Quality in the Maine DEP, although it is more typical that 11 to 25 lakes are documented as having blooms each year, according to state data.
Bouchard said that he has not heard reports of exposure to blue-green algae toxins in Maine; however, he added that one reason might be that some of the symptoms—in both people and dogs—include vomiting and diarrhea. That could lead people to blame other causes, such as that a dog “got into something.” According to Bouchard, the additional data on toxicity that he began to collect last year may help develop a warning system that may be used as early as next summer, but but not before then.
Meanwhile, and because he cannot track toxicity at every one of Maine’s 5,900 or so lakes and ponds—even with the help of Maine Volunteer Lake Monitors (mainevolunteerlakemonitors.org)—Bouchard suggests that people stay away from lakes that are “really green and murky,” especially when algae are concentrated together on the surface, and to be certain that their dogs do not drink from or swim in these bodies of water. Other states also suggest washing a dog’s coat if she has taken a swim in questionable water to prevent her from ingesting algae while cleaning her fur.
Bouchard said that seeing plants in the water is quite normal and can often be a sign of a healthy body of water; the concern should be about algae, “murky fine particles that are free-floating with no obvious structure,” he said.
Roberts suggests using common sense about where you let your dog swim, “If you don’t want your kids playing in a certain area, you shouldn’t let your dog go there either.”