Harmful Algal Blooms and Animal Health

First and foremost, learn about harmful algal blooms and what to look for. Higher levels of toxins are typically associated with cyanobacteria blooms that appear as thick foam or scum on the water’s surface. Their color can vary from bright green and blue-green, to white, red or yellowish-brown. The water may look like pea soup or the surface may look as if paint has been spilled on it. As the cyanobacteria begin dying and decomposing they may release an unpleasant odor similar to rotting plants.

• If the water does not look or smell right or you suspect a bloom is occurring, it is best to avoid direct contact with the affected area. If the affected waterbody is a farm pond used for watering livestock, it is best to prevent them from accessing the pond by temporarily fencing it off, and providing another source of fresh water.
• Before allowing pets to swim in lakes, rivers or at beaches, check for posted water quality condition information. This information may be online, at the park office or posted at common access area, such as bath houses or boat ramps. You can also check the Missouri HAB Response Team's Harmful Algal Bloom Reports Map for locations where HABS have been reportedly observed in Missouri.
• Do not let pets drink or play in the water or roll in or eat the algae, even if dried. Dogs can also be affected by licking their fur after having been in contact with the algae scum.

Symptoms generally begin minutes to hours after exposure to the toxins. The symptoms animals may experience will depend on the type of toxin present and how the animal was exposed. The severity of the symptoms will depend on the amount of toxin ingested, the animals body size, amount of food in the stomach and the sensitivity level of each individual animal. Common symptoms include:

In the worst cases, animals may suffer convulsions and die.

If you are concerned your animals may have been in contact with or ingested contaminated water, wash them off with fresh water immediately. If your animals are experiencing any symptoms related to exposure, contact your veterinarian. Let your veterinarian know your animals may have been exposed to cyanobacteria, also known as blue-green algae. You can also call the ASPCA Animal Poison Control Center at 888-426-4435 or the Pet Poison Helpline at 855-764-7661 for questions about animal health. Note that there is a fee for these calls.

Any algae bloom, whether toxic or not, can lead to low oxygen levels in the waterbody. This can lead to high mortality rates in fish, shellfish, invertebrates and plants. Dense blooms can affect the amount of light that can penetrate into the water, adversely affecting plants and other organisms living on the bottom.

Fish caught in affected waters pose unknown health risks and may have an undesirable taste. Because of the unknown risks, we recommend you do not eat fish from affected areas for two weeks after the bloom visually dissipates. If you choose to eat them, remove all fat, skin and organs before cooking because toxins are more likely to collect in these tissues. Always cook fish thoroughly.

General Information

• Algal Poisoning - Merck Manual
• Animal Safety Alert: Cyanobacterial Blooms and Animals - CDC
• Blue Green Algae & Me - DHSS
• Cyanobacteria Blooms
• Dogs and Harmful Algal Blooms - NOAA
• Harmful Algal Blooms and Blue-green Algae - PUB3051
• Look Out Harmful Algal Blooms - PUB2889
• Natural Water Areas - DHSS
• Preventing Pet and Livestock Illnesses Caused by Harmful Algal Blooms - CDC
• Protect Your Pooch from HABs - EPA video

Veterinarians and Other Animal Health Professionals

• Algal Poisoning of Animals - Merck Manual 
• For Veterinarians: Harmful Algal Bloom-Associated Illnesses - CDC
• Veterinarian Reference for Cyanobacterial Blooms - CDC