Toxic Algae In Lakes Can Poison Dogs — Here’s How To Keep Your Pets Safe

Portrait of a sad stray dog on the background of the lake

The green stuff growing in our lakes, ponds, and rivers may seem harmless, but this water can be fatal for your dog. Recent incidents have left some dog-owners wondering if it's safe to take their pets for a swim or let them drink the water. But by learning the signs, you can keep your dog safe from toxic algae.

TODAY and other outlets have reported the deaths of three dogs in Wilmington, North Carolina and the death of a dog in Lake Allatoona, Georgia. All four were swimming in lakes and ponds before their deaths, and were exposed to toxic cyanobacteria.

The Center for Disease Control says that cyanobacteria are single-celled, microscopic organisms found naturally in all types of water. They reside in fresh, brackish (combined salt and fresh water), and salt water, and use sunlight to make their own food. Warm temperatures and high levels of phosphorus and nitrogen can cause the bacteria to multiply rapidly, resulting in "blooms" that spread and may become visible.

The United States Environmental Protection Agency (EPA) says that these harmful algal blooms need sunlight, slow-moving water, and nutrients (nitrogen and phosphorus) to blossom. According to the EPA, nutrient pollution from human activities leads to more frequent, severe blooms.

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As rising temperatures and pollution increase as a result of the climate crisis, it’s important to remember that bodies of water will be impacted in many ways, including increased levels of toxic cyanobacteria.

The algae has been observed in large freshwater lakes, smaller inland lakes, rivers, reservoirs and marine coastal areas and estuaries in all 50 states, David G. Schmale III, a professor at Virginia Tech, told CNN Health. Toxic algae can also flourish in decorative ponds and backyard pools, so it’s important to sanitize water and get it tested if you suspect cyanobacteria may be present.

For animals, symptoms of exposure to cyanotoxins can include excessive salivation, fatigue, difficulty breathing, vomiting, diarrhea and seizures, according to the EPA. The World Health Organization (WHO) says that, depending on the type of toxin and the type of water or water-related exposure (drinking, skin contact, etc.), humans might experience symptoms like skin irritation, allergic reactions, stomach cramps, vomiting, nausea, diarrhea, fever, sore throat, headache, muscle and joint pain, blisters of the mouth and liver damage.

However, bodies of water with toxic cyanobacteria will often have a "No Swim" sign, so that humans won't be exposed. Dr. David Dorman, a board-certified veterinary toxicologist and professor of toxicology at North Carolina State University, told TODAY that humans and animals should pay attention to these signs. “If it’s not safe for you to use the water, it’s not safe for your pets either,” Dorman said. "Dogs are the domestic animal most susceptible to cyanobacteria because they love to swim and drink from lakes and ponds, and will [enter] the water no matter what the smell or appearance."

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So, how can you tell if you're in the presence of toxic cyanobacteria? According to the Colorado Department of Public Health and Environment, you can spot harmful algal blooms by looking out for the following signs:

  • "May look like thick pea soup or spilled paint on the water's surface.
  • "Can create a thick mat of foam along the shoreline.
  • "Usually are green or blue-green, although they can be brown, purple or white.
  • "Sometimes are made up of small specks or blobs floating just at or below the water's surface.

The department stresses that these types of algae are not harmful algal blooms:

  • "Long, stringy bright green grass strands that feel either slimy or cottony.
  • "Mustard yellow (this probably is pollen).

Blue-green algae can also cause fatal poisonings in other animals, including cattle, sheep, chickens, pigs, horses, poultry and wild birds, fish, or even rhinoceroses, according to an article published by Interdisciplinary Toxicology. With almost 3,000 species at risk for extinction due to human activity — according to the Red List report by the International Union for Conservation of Nature (IUCN) — we should take the risk that cyanobacteria poses to animal life very seriously.

It's heartbreaking that these dogs lost their lives to this bacteria. But with a little bit of prevention and climate activism, we can help reduce the number of fatalities that this toxic algae may cause.