The Dangers Of Blue-Green Algae

By Deb Haines

Blue-green algae (also known as cyanobacteria) are non-pathogenic photosynthetic bacteria that grow in outdoor water bodies and produce toxins such as microcystins, cylindrospermopsin and anatoxin-a. They can grow quickly and form large blooms, especially in warm weather. Blue-green algae can cause signs of poisoning in as little as an hour. Death has been reported within just a few hours. Signs of vomiting, collapse, seizures and coma can be almost immediate, and often it’s too late to treat by the time the pet gets to a veterinary clinic.

Blue-green algae

Although dogs are most commonly affected, blue-green algae can be toxic — and even fatal — to cats, horses, livestock, birds and other wildlife that drink from contaminated pond or groom themselves after being in the water. For people who water ski or swim in water containing toxic blue-green algae, or who inadvertently swallow the organisms, exposure can also lead to illness and death.

Not all blue-green algae are toxic. The conditions have to be right. This usually occurs in hot weather from mid-summer to fall, when the water temperatures are at their warmest. The combination of sunlight as well as nutrient-rich phosphorus and nitrogen from fertilizer runoff and decaying fish and plants encourage the organisms to grow into toxic colonies, or “blooms.”

Blue-green algae can produce a number of different toxins, including microcystins and anatoxins. The signs in a dog can vary depending on the type and amount of toxin ingested.

Microcystins can cause liver damage, which can lead to weakness, vomiting, diarrhea, a yellowish tint to the skin bloody or black stools ,pale or yellow gums, seizures, and coma. Anatoxins, on the other hand, tend to affect the central nervous system. Signs may include excessive drooling or tearing, muscle tremors, paralysis and difficulty breathing, resulting in a bluish tone to the skin and gums.

Because toxic effects can happen quickly, if you suspect your dog has been exposed to blue-green algae, it’s important to seek veterinary help immediately. When in doubt, contact your veterinarian, emergency veterinarian or even poison control link….

BE SMART ….check the local and state swimming advisories to see if there are any blue-green algae warnings. And if the water looks suspicious, it’s better for your dog and your family to stay out.


Animals can be exposed to blue-green algae and its toxins by:

  • Contacting any infected water body including lakes, rivers, ponds, etc. Because animals are attracted to blue-green algae, they drink the water and eat algal material. Dogs in particular lick algae caught in their fur after being in the water.
  • Consuming water and algae from residential pools or decorative ponds.
  • Ingesting blue-green algae health supplements.

Where do these algae grow?

Harmful algae can bloom in both fresh and marine water. They’ve been observed in large freshwater lakes, smaller inland lakes, rivers, reservoirs and marine coastal areas and estuaries.

Toxic algae can also grow in decorative ponds as well as backyard pools, providing homeowners with a good reason to properly sanitize swimming water.

What do toxic algae look like?

Toxic algae can look like foam, scum, or mats on the surface of water, said Schmale. Harmful algae blooms, which can be blue, vibrant green, brown or red, are sometimes mistaken for paint floating on the water.

Toxic algae often stink, sometimes producing a downright nauseating smell, yet animals may be attracted to the smell and taste of them, according to the EPA.

Can I be harmed by the algae?

When high concentrations of these cyanotoxins are consumed, they can poison not only domestic animals but also humans. Contact with toxic algae can cause rashes, stomach cramps, nausea, diarrhea and vomiting.

PVC Vets

Dr. Bethany Moats.…. Some blue-green algae blooms are toxic to both humans and dogs. It’s impossible to tell by looking at the algae whether or not it is currently producing toxins. Algal toxins cause a ute liver failure and death. I would not allow dog to swim an algae-covered ponds, ever. Sure, they may swim safely 90% of the time, but that 10% (these numbers are entirely fictional and just for example) chance of death is not worth the enjoyment. Looks for algae-free ponds or flowing water to keep everyone, yourself included, safe while enjoying water. If you have a personal pond, take measures to prevent algal blooms.

Link to Hot line on blue green algae……

Information provided from Vetstreet …..

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