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Information for Animal Owners and Veterinarians

Cyanobacteria (also called blue-green algae) can rapidly grow out of control or “bloom” in all types of water and seasons but are most common in warmer months. These events are referred to as a harmful algae bloom (HAB). Cyanobacteria can produce toxins (poisons), known as cyanotoxins. These toxins are harmful, and potentially deadly, to animals. Be mindful of potential harmful algae blooms when walking pets near waterbodies or when using waterbodies as a source of water for livestock. Do not let animals contact or consume water that has foam, mats, scums, unusual paint-like streaks or colors, or foul odors. 

Be aware that it is impossible to tell if toxins are present during a bloom without a laboratory test. Therefore, it is best to use caution and limit all pathways of exposure, such as; inhalation of water spray or mist, contact, consumption, etc.  If contact with a cyanobacteria bloom occurs or is suspected, immediately clean the affected animal with soap and clean water. Continue to observe pets and livestock for signs of cyanotoxin poisoning as sickness and death can occur within minutes to days following exposure. 

Symptoms of Cyanotoxin Poisoning Can Include:

  • Skin irritation
  • Lethargy (loss of energy, tiredness)
  • Excessive drooling/Foaming at the mouth
  • Loss of Appetite
  • Vomiting
  • Labored breathing
  • Stumbling/Falling
  • Seizures/Tremors/Convulsions
  • Diarrhea
  • Unexplained sickness after exposure
  • Organ failure
  • Death

If you suspect that your pet or livestock are experiencing signs of cyanotoxin poisoning, contact your veterinarian or Poison Control (see below) immediately. Although there are currently no clinically available tests or designated treatments for cyanotoxin poisoning, it is critical to seek supportive veterinary medical care as soon as possible.

Steps You Can Take to Protect Your Animals:

  1. Familiarize yourself with bloom appearance and signs of toxin exposure.
  2. Inspect waterbodies before letting pets or livestock contact or consume water.
  3. Provide alternative water sources.
  4. Fence off or limit access to contaminated waters.
  5. Observe posted signage.  
  6. Report suspected blooms using the Bloom Report Form to Illinois EPA and your local health department.
  7. Adopt conservation practices that prevent and reduce nutrient loading to waters which will minimize future blooms.
  8. Check the Illinois EPA Harmful Algal Bloom Dashboard to see where blooms have been reported.
  9. When in doubt, keep animals out!

Resources for Animal Owners and Veterinarians

Phone Numbers:

Poison Control: 1-800-222-1222

ASPCA Animal Poison Control Center: 1-888-426-4435 (Note: A consultation fee may apply for calls.)

Pet Poison Helpline: 1-855-764-7661 (Note: A per incident fee applies to calls.)

American Veterinary Medical Association

Centers for Disease Control and Prevention

Preventing Illnesses Caused by Harmful Algal Blooms

Preventing Pet and Livestock Illnesses Caused by Harmful Algal Blooms

Veterinarian Reference Card

North Central Region Water Network

Harmful Algal Blooms and their Health-Related Effects on Animals:

U.S. Department of Agriculture

How to Protect Livestock from HABs:

Printable Fact Sheet:

U.S. Environmental Protection Agency

How to Protect Your Pooch