Blue-green algae (i.e., cyanobacteria) thrive in stagnant, warm water and produce hazardous bacterial toxins (i.e., cyanotoxins). Each blue-green algae species produces a different toxin, the worst of which attacks a pet’s nervous system and liver. The toxin often attacks rapidly, and an affected pet may not survive long enough to receive emergency, lifesaving treatment.

Cyanotoxin reports mainly occur in southern U.S. states, so our Neighborhood Veterinary Centers of Nasa team is sharing information to help you protect your Southeast Texas pets. Learn important facts about blue-green algae toxicity in pets.

Blue-green algae pet toxicity types

Blue-green algae appear as blue-green, red, or brown foam or scum on stagnant, warm water, which may be more likely to grow after periods of little or no rainfall. Heavy algal growth can also cause a foul odor without visible scum. The algae can develop anywhere, including backyard pools, ponds, and puddles, but most growth occurs in the warmer U.S. states

More than 30 species of cyanobacteria each produce their own toxins. These toxins are generally categorized as follows:

  • Hepatotoxins (i.e., liver toxins)
  • Neurotoxins (i.e., nervous system toxins)
  • Dermal toxins (i.e., skin toxins)
  • Nephrotoxins (i.e., kidney toxins)

Blue-green algae pet toxicity signs

Hepatotoxins (i.e., microcystin) and neurotoxins (i.e., anatoxin) are the most dangerous to pets, often causing multiple illness signs as quickly as 15 minutes after exposure. However, signs sometimes take a few days to develop. Pets may go into shock from multiple organ failure or develop respiratory distress from neurotoxin paralysis. Signs vary and may include the following:

  • Vomiting
  • Diarrhea
  • Weakness
  • Pale, yellow, or blue gums and mucous membranes
  • Bloody or dark black stools
  • Seizures
  • Muscle rigidity
  • Paralysis
  • Collapse
  • Difficulty breathing
  • Coma
  • Death

Blue-green algae pet toxicity diagnosis and treatment

Our Neighborhood Veterinary Centers of Nasa team usually diagnoses blue-green algae toxicity presumptively based on a pet’s signs, recent exposure to a potentially dangerous water source, or reports of a known bloom occurring in the area. If you bring in a sample of the water in which your pet has been, our team can test it to confirm your four-legged friend’s diagnosis. While water sample testing may not save your pet’s life, our team can help environmental agencies identify the algae and help prevent other pets from becoming ill. 

A cyanotoxin antidote does not exist, and treatment is entirely supportive. Vomit induction, stomach pumping, or activated charcoal may be used if a pet presents shortly after a known or suspected toxin exposure, but most are too sick when they arrive at the veterinary hospital to undergo decontamination treatments. Aggressive fluid therapy, blood transfusions, medications, and ventilation support are a pet’s best survival opportunity, however, mortality is high despite treatment. 

Blue-green algae pet toxicity prevention

Pets often die from blue-green algae toxicity, so prevention is the best way to keep your pet safe. Consider the following prevention strategies:

  • Check with your local environmental, park district, or government office for known algal blooms before venturing on your next hike.
  • Avoid letting your pet drink or swim in water with visible algae, scum, foam, or a foul odor.
  • Remove stagnant water sources from your yard to prevent algal blooms. By doing so, you’ll also get rid of mosquito larvae, an added bonus.
  • If you think your pet has been exposed to blue-green algae, rinse them with fresh, clean water and seek immediate veterinary attention.

The long-term outlook for pets with blue-green algae toxicity

Many pets exposed to neurologic or hepatic toxins do not survive because the toxins act so quickly. These pets may pass away on the way to the veterinary hospital or upon arrival, or may require euthanasia because the damage to their organs is too significant. This toxin can devastate pet-owning families, as it may affect multiple pets who go on adventures together. One 2019 case resulted in three pet deaths within the same household after exposure to an algal bloom. A pet who survives the initial illness with intensive care will likely suffer from permanent organ, brain, or other nervous system damage, and will require ongoing treatments. 

You cannot visually tell the difference between toxic and nontoxic algal blooms, so caution is advised anytime you plan to swim with your pets. Check with local authorities to obtain information about or to report a suspected algal bloom, and keep your pet out of visibly scummy or smelly water. Seek care immediately with our Neighborhood Veterinary Centers of Nasa team or your local Southeast Texas veterinary emergency facility if you suspect your pet has been exposed to blue-green algae.