Albany, N.Y. — Ever since the return of harmful algae blooms (HABs) to North America in greater numbers, there have been an increasing number of cases in which dogs have gotten sick and even died after exposure to the toxins that are sometimes produced by cyanobacteria, commonly known as blue-green algae.
Dog owners can become more aware of this danger, thanks to David MacNeill, fisheries specialist at the New York Sea Grant program. He authored a brochure in August, now available as a pdf called, “Dogs and Harmful Algal Blooms (HABs)” through a collaboration with various universities and agencies, with some of the highlights listed below.
To download the New York Sea Grant brochure used for this article, go to seagrant.sunysb.edu/btide/pdfs/HABsBrochure-0814.pdf.
As the hunting seasons begin, hunters with dogs need to be vigilant about the condition of the water that their dogs are exposed to while retrieving waterfowl or seeking refreshment in an upland field stock pond, wetland, or puddle.
Fortunately, by the time many of the hunting seasons are upon us, the peak of the HAB season has passed. However, this information is useful wherever suspected algae blooms are encountered, normally late summer through the fall.
Unfortunately, many of the areas that hunters will be taking their dogs are not tested for HABs, so suspected algae must be recognized by sight.
To recognize a HAB, suspect any green to blue-green water surface that can sometimes show signs of red or brown. It has also been described as looking like pea soup or green paint, scum, mats, white froth, or dirty foam. Waves can push any of these forms of HABs ashore with moderate winds.
Toxins that are released through the decay of the algae cells or after consumption may affect the nerves, liver, or skin when in high concentrations. Dogs can be poisoned while swimming, drinking tainted water, chewing on algal mats, or by grooming their fur or paws after exposure to HABs.
Since toxin concentrations and types vary widely, there is no way to predict individual outcomes of dogs exposed to algae, but they can range from no effect to death.
Variables affecting the outcome include type of toxin, toxin concentrations, amount consumed, the length of exposure time to the toxins, and the size of the dog. There is no way to tell by looking at the algae if it is toxic or how toxic it is.
According to the California Department of Environmental Protection, liver toxins can show delayed effects at 2 to 40 parts per billion (ppb) and rapid health effects at levels greater than 100 ppb. Nerve toxins require levels of 2 to 100 ppb for delayed effects with rapids effects also occurring at levels over 100 ppb.
In general, smaller dogs are at greater risk of adverse effects from HAB exposure. In some cases, death can occur within 30 minutes to a couple of hours after exposure.
Repeated exposures to lower concentrations can be as harmful over time as a single exposure of a higher toxin concentration.
View the California report at swrcb.ca.gov/water_issues/programs/peer_review/docs/calif_cyanotoxins/cyanotoxins053112.pdf.
Common signs of HAB toxin poisonings in dogs include the individual or combination of symptoms listed at right.