Microcystin Algal Blooms a Danger to Dogs But New Treatment Shows Promise

A paper on sea otters dying from exposure to cyanobacteria along the coast of California may have saved the life of a dog in Montana. Dr. Melissa Miller and her team from the Marine Wildlife Veterinary Care and Research Center… of the California Department of Fish and Game had looked into potential treatments for microcystin poisoning after a number of sea otters died from exposure. An experimental treatment she found led to the cure of the Montana dog.

Decoded Science, in an interview with Dr. Kelly Rankin, the Montana dog’s veterinarian, learned more about the use of Cholestyramine and other supportive care to treat microcystin, exposure.

Blue-green Algae Toxins Affect Many Species

This problem is not new. Cyanobacteria, blue-green algae, are just one of the many toxic forms of harmful algal blooms (HABs).

Red tide, for example, is caused by a completely different algae, and even within the cyanobacteria family, microcystin is only one variety. Different HABs act in different ways; some affect the nervous system, some the gastrointestinal systems and some, like microcystin are hepatotoxic, affecting the liver.

Outside the US there is a report of three dogs in the Netherlands dying from microcystin poisoning, the first confirmed cases in that country. Humans, birds, fish, and even marine mammals have died from exposure to microcystins.

In the California case, 21 sea otters deaths were linked to microcystin exposure. Postmortem testing confirmed the cause of death but until then no one knew what was affecting them. In fact, prior to that incident, it was thought that microcystins would not survive in the marine environment.

What Dog Owners Should Know About Exposure to Cyanobacteria

Dr. Rankin suggests that dog owners not allow their pets to play in or drink water that looks slimy, particularly if the slime has an iridescent blue-green color. Given that microcystins are found in the marine environment, as in the case of the sea otters in California, and in deserts, as described by a letter to the Veterinary Record, any healthy dog that exhibits sudden symptoms with no other obvious exposure risks, should be considered as a potential microcystin case.

In a report to the Veterinary Record, the alga was identified in the dried crusts on the desert surface. It is presumed that the dogs ingested some of the cyanobacteria while drinking rainwater from puddles. Two of the four dogs in this report died, the other two recovered.

What are the Symptoms of Microsystin Toxicity

So what should owners be aware of after a trip to the lake, or after their dog has been drinking from stagnant puddles? Lethargy, anorexia and vomiting were the initial symptoms.

Blood tests showed elevated liver enzymes. Five days after exposure to the algal bloom other evidence of liver failure, including dark urine, tarry stools, and blood coagulation problems were noted. In other cases, dogs have also developed severe diarrhea.

Green areas indicate presence of cyanobacteria. Photo Credit: NASA Earth Observatory
Green areas indicate presence of cyanobacteria. Photo Credit: NASA Earth Observatory

First Reported Successful Cholestyramine Treatment in a Micrycystin Exposed Dog

When Dr. Rankin first admitted the dog, she began supportive care, which included IV fluids, antibiotics and a nutritional supplement, Denmarin. Dr. Rankin told Decoded Science that she has used Denmarin, which combines milk thistle and S-Adenosyl Methionine (S-AME) for other dogs with liver problems as it supports liver function. While this may have helped, Dr. Rankin told Decoded Science that the product is only available as a large pill, thus not an option for dogs that are vomiting or nauseous.

As her patient’s symptoms worsened, Dr. Rankin began searching for more information on what could be causing the problem and what else she could do. She was eventually put in touch with Dr. Miller who told her about a product that had only been tested in the laboratory on rodents. Dr. Rankin elected to try the experimental drug, Cholestyramine, one of the early human medications for the control of high cholesterol, hence the name.

Over the next two days the dog improved dramatically and was soon able to go home. A recheck 17 days later showed that her liver enzyme levels had returned to normal.

Results for One Dog Are Not A Guarantee for Success in Every Case

Because this report documents a single case, not a controlled study, the results must be interpreted with caution. Cholestyramine binds strongly to bile salts which attach to microcystins and to the microcystins themselves so it is likely to be helpful in other microcystin poisoning cases.

On the other hand, Cholestyramine would not necessarily help a dog who is experiencing neurological or other organ symptoms as it is unknown whether it binds to other types of toxic algae.

It is also important to remember that not every animal will react in the same way to a medication. The dog in the study did not experience any serious side effects but other dogs may be more sensitive.

Nonetheless, treatment with Cholestyramine is worth discussing with your veterinarian should your dog, who might have been exposed to water sources that may contain cyanobacteria, suddenly become seriously ill with severely elevated liver enzymes.

According to Dr. Rankin, the treatment turned her patient around quickly, and at a point where her condition was worsening despite intense supportive care. And Cholestyramine is inexpensive and readily available at any pharmacy.

 

Photo caption: Playing in or drinking stagnant water may expose dogs to micrycystin. Photo Credit: Ronald Laubenstein, USFWS

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