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Toxic Algae: Hazard for Dogs

Toxic Algae: Hazard for Dogs

Toxic algae poisoning, also known as cyanobacterial poisoning, is an acute, sometimes fatal, condition caused by the ingestion of water containing high concentrations of cyanobacteria. Due to the species of cyanobacteria that have a tendency to bloom in the Pacific Northwest, the cyanotoxins of primary concern to Oregon include microcystin, a hepatotoxin, and anatoxin, a neurotoxin.

In Oregon, dogs have become very sick, and some have died, after swimming in and swallowing water affected by toxic blue-green algae.

Poisonings are most likely to occur during warm, sunny weather when algae blooms are more intense and dense surface scums are present. If you find thick, brightly colored foam or scum at a lake, pond or river, don’t let your pet drink or swim in the water.



Children and pets are particularly susceptible to toxic algae. Exposure to blue-green algae can result in:

  • Weakness or collapse
  • Nausea, vomiting
  • Excessive drooling
  • Abdominal pain
  • Diarrhea
  • Difficulty breathing
  • Shaking, trembling
  • Tremors, rigidity, paralysis

If Your Dog Does Go in the Water

  • Don’t let your pet lick its fur.
  • Wash your pet with clean water as soon as possible.
  • If your dog shows the symptoms noted above after being in water, seek immediate veterinary care. Acute, life-threatening symptoms can develop rapidly. Death can occur within minutes to hours after exposure.


Treatment depends on the type of toxin and how much damage has occurred, and may include aggressive decontamination, labs to evaluate liver health, fluids to help flush the toxins out of the body, activated charcoal. A dog may require aggressive care for shock, respiratory distress, or acute liver failure.

Updated: June 1, 2022