Summer brings toxic cyanobacteria to ponds

Published 4:47 pm Tuesday, August 13, 2019


K9 Corner

Since it is summer and hot and humid, I would like to repeat a column I wrote in 2013 regarding toxic algae that grows in ponds. Since the poison caused by a bacterium affects a number of mammals, including humans, I feel that it is an important subject to address at this time.

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According to an article titled “Cyanobacteria: Life History and Ecology” (found at ), this bacterium is microscopic and rich in chemical diversity. The name comes from the bluish pigment phycocyanin, which is used to capture light for photosynthesis. The bacterium also has chlorophyll, which gives the bluish-green cast to the pond scum, also called algae.

Fortunately, the organism has difficulty growing in moving water (streams), but at this time of the year, the warm summer weather has warmed stagnant pond waters sufficiently to provide a perfect growth medium.

Why is this important to alert dog owners? In another article, a Jack Russell terrier that decided to have a drink from a pond near where his owners were picnicking reacted within hours after the drink by having convulsions and dying. The news article stated that tests showed the dog was filled with cyanobacteria, also called blue-green bacteria (or algae) and the pond water tested positive for the same organism.

What is so alarming to me are the facts listed that blue-green algae is toxic not only to dogs and cats, but also to horses, cows, birds and people. Hunting dogs are specified as being at higher risk due to increased exposure outdoors. Symptoms include vomiting, diarrhea, blood in the stool or a black tarry stool, pale mucous membranes, jaundice (yellowing of the whites of the eyes and the gums), seizures, disorientation, coma, shock, excessive drooling or tearing, muscle tremors, muscle rigidity, bluish discoloration of skin and mucous membranes, difficulty breathing and ultimately, death.

Reactions to exposure depend on the toxin involved. One toxin attacks the liver; another toxin invades the nervous system, which can bring on death in minutes to hours due to respiratory paralysis. One isn’t so bad; it only causes “swimmer’s itch” in humans.

Now, here’s some information that will seem confusing. There are different species of cyanobacteria, some are “good guys,” actually, at least one is edible, that is Spirulina. It is high in protein and can be cultivated in ponds quite easily. The Berkeley article says that “In tropical countries, it may be a very important part of the diet.” However, since blue-green algae has been linked to poisoning of cattle, dogs and occasionally people, any blue-green algae should be avoided, unless you know which species of the organism you are gathering, or swimming in.

It’s important to understand no antidote currently exists for the toxins produced by blue-green algae. If you suspect your dog or other animal was exposed to blue-green algae, contact Pet Poison Helpline at 1-800-213-6680. It is open 24/7 so call immediately for guidance.