Did you know that as summer approaches, visits to the animal emergency room increase? Dangers like trauma (off leash, running around outside and getting hit by a car), poisonings (spring toxins like poisonous plants, fertilizers, etc.) and heat stroke are all more prominent. But there is one danger most pet owners aren’t aware of: swimming in lakes. Next week we’ll talk about the dangers of swimming in the ocean.

While I don’t want to make you paranoid about allowing your dog to swim in a lake, I do want you to be aware of cyanobacteria dangers; I’ve seen it up and close. While visiting Madison, WI a few summers ago, I noticed what looked like blue or green iridescent paint on the surface of a lake: blue-green algae. Last year while visiting London, I saw some in the royal ponds, too.

Cyanobacteria (also known as blue-green algae) are microscopic bacteria found in freshwater lakes, streams, ponds and brackish water ecosystems. Blue-green algae grow and colonize into "blooms." While blue-green algae aren’t present in all bodies of water, when they are present you’ll notice a "pea soup" or blue-green color floating on the surface of the water. Because the algae float, the thick, concentrated mats can be blown by the wind close to shore, making this potentially deadly poison easily accessible to livestock, pets and people.

Most blue-green algae blooms don’t produce dangerous toxins, but unfortunately, certain types of blue-green algae can produce toxins; specifically microcystins and anatoxins, which are poisonous to two-legged and four-legged mammals alike. It’s impossible to visibly distinguish dangerous algae from benign algae without appropriate testing. Swimming or drinking from water that’s been contaminated with blue-green algae can result in severe, acute poisoning. Even small exposures, as little as a few mouthfuls of algae-contaminated water, can potentially result in fatal poisoning.

Clinical signs of poisoning are dependent on the toxin involved. One type results in liver failure, while the other type results in severe neurologic (central nervous system) signs.

With the blue-green algae that produce microcystins, symptoms include:

  • Vomiting
  • Diarrhea
  • Not eating
  • Black-tarry stool
  • Weakness
  • Lethargy
  • Pale gums
  • Jaundice (yellow) gums
  • Shock
  • Death

With the blue-green algae that produce anatoxins, symptoms include:

  • Excessive drooling
  • Excessive (eye) tearing
  • Muscle tremors
  • Muscle rigidity
  • Inability to walk
  • Difficulty breathing or blue gums
  • Death

Immediate veterinary intervention is needed with any type of potential poisoning, but in general, once signs of blue-green algae poisoning have developed, the prognosis is very poor. Unfortunately, there is no antidote for the toxins produced by blue-green algae.

With any poisoning, the sooner you seek treatment the better the prognosis. With blue-green algae, immediate veterinary attention is important. You can also call Pet Poison Helpline for assistance at 855-213-6680.

Better yet, keep your pet away from lake water — particularly if you notice that color. No need to be paranoid, but take a good look around at the lake shore before you and your pet romp in the water!

Dr. Justine Lee

Image: Joshua Rainey Photography / via Shutterstock