From the Bay to the Blue Ridge, To the Blue Ridge



The photos with the dogs in them, although the algae looks similar, the owner had the pond tested and this was just garden variety pond scum, not toxic blue green algae! No dogs were harmed in the taking of the photos. Photos by Julie Reardon

About the time dire warnings about dog deaths from blue-green algae hit social media, we had an unusually thick mat of algae in the pond closest to our house. We knew the pond was not draining correctly because of a collapsed drainage culvert that needed an expensive repair, and because of the algae, we tried to keep the dogs out of it, but we never worried about toxicity. Then, in early August, we had a massive fish kill. Hundreds of bass and bluegills floated on the surface.

Turns out, our fish kill was because the thick mat of algae on the surface was starving the fish of oxygen and coupled with the July heat wave, killed all but the catfish. Ours was fortunately not, however, the dog-killing blue-green algae. It’s common in late summer for ponds and lakes to become covered with algae blooms and aquatic vegetation that can be unsightly and form large, smelly mats on the water surface. Most is unattractive and smells disgusting but not harmful. Some can be deadly to dogs. These blooms of algal overgrowth tend to become worse after heavy rains and excessive periods of higher than normal temperatures, both of which we’ve had this summer. Recently reports have surfaced that dogs have died after exposure to a toxin commonly referred to as blue-green algae. Reports of dog deaths from the harmful algae blooms or HABs in North Carolina, Georgia and Texas have made headlines nationally and people have become scared for the safety of their pets. As did we after our fish kill, but testing revealed ours was just an overgrowth of run of the mill algae.

The toxin that is harmful to dogs (and humans) is not actually algae, rather it’s a bacteria known as cyanobacteria that can be found on still or stagnant water surfaces and when present in large amounts can form a film or scum that looks like algae and is often blue green in color. Also known as blue-green algae, when the bacteria grow in excess they can look like algae but to confuse things, not all clumps of blue green scum on ponds contain the harmful cyanobacteria, a neurotoxin. And the cyanobacteria are not always blue green; they can be green or red or brown. These organisms are commonly found in trace amounts in many waters and normally present no problem until there is an abundance of them caused by excessive nutrient run off or unusually warm stretches of weather.

Locally, the HABs have been confirmed in a few Maryland and Virginia lakes and ponds, but officials admit they do not have the resources to test private ponds and lakes. To date, no dog deaths have been reported from either Maryland or Virginia. Common sense dictates that most humans know to avoid stagnant scummy pond water for swimming and recreation but dogs harbor no such caution so it’s wise to keep your dogs leashed near water that you suspect could be contaminated. Dogs are particularly susceptible because they like to play in and drink from the water, and may ingest some retrieving or playing. They are also likely to lick it off their paws and coat.

If you suspect your dog has been in contaminated water, rinse it off with clean water immediately and watch for any symptoms of blue-green algae poisoning. These can happen as soon as 15 minutes after exposure up to several days later and include vomiting, diarrhea, drooling and neurological signs such as weakness, disorientation/staggering, lack of coordination, collapse and/or unconsciousness and seizures. Consider any of these symptoms an emergency requiring immediate veterinary attention if your dog has been around any water you suspect might be toxic. Contact your vet immediately; often dogs can be saved if the toxins are flushed out of their system soon after contact.

Are blue-green algae blooms dangerous for humans?

Most species are not toxic, but some blue-green algae can produce neurotoxins (nerve) toxins or hepatotoxins (liver) during blooms that may be harmful to humans.

Exposure can come from swallowing water, direct skin contact, and breathing aerosolized bacterial toxins that are in the air.

If water containing blue-green bacterial toxin or cell components is swallowed, gastrointestinal symptoms such as stomach pain, nausea, vomiting, and diarrhea can result. If direct contact is made; skin and eye irritation can result, with symptoms such as tingling or numbness of the lips, fingers and toes and dizziness.  Respiratory irritation can result from breathing air that contains toxins or cell components. Long-term exposure to blue-green bacterial toxins may result in liver damage. Effects due to HAB nerve toxins may appear within 15-20 minutes of exposure while liver toxin symptoms may take hours or several days to appear following exposure. If you are concerned that you have been exposed to a harmful algal bloom, please see your doctor or health professional. Telling your doctor about contact with water may help him/her treat the illness properly.

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