LAMORINDA WEEKLY | Swim or stay out of the lake?


Illustration Jaya Griggs

A local veterinary hospital recently had a case that involved a get-away dog walking at the Lafayette Reservoir, who ended up swimming the length of the reservoir before entangling her leash in the weeds on the far end, enabling her rescue. In addition to being exhausted and frightened, this dog was potentially exposed to blue-green algae toxicity, and was hospitalized at one of the local 24-hour emergency hospitals. Although I have yet to see any formal announcements this year from the East Bay Municipal Utility District or the East Bay Regional Park District about this potentially deadly liver toxin, it reminded me to get the word out. It's one of the reasons to not allow your dog to swim in water containments that specifically don't allow people or pets in the water.

Blue-green algae is a natural bacterial component in most lakes. Under the right conditions, the algae goes into a bloom and some of these algae species can release cyanotoxins. These conditions include low-level water, limited water circulation and increase in heat and light. Blooms usually last a couple weeks before they dissipate. Toxicity in a patient occurs when the toxin is ingested or through skin contact. Signs involve skin rashes and irritations, nerve disease, or sudden severe liver damage. Unfortunately, the mortality rate is fairly high for patients with the neurologic or liver damage form. Signs are vague and include lethargy, not eating, vomiting, diarrhea, abdominal pain and even shock. Signs occur well within 24 hours of exposure. There is no specific antidote to the toxin. There is also no specific test to check for the presence of the toxin, so knowing your dog's environmental exposure is a key factor in the diagnosis. Immediate aggressive veterinary care is recommended, including intravenous fluids and liver support injections, as well as monitoring bloodwork. Often, dogs are treated for a few to several days with intensive care support.

According to the East Bay Regional Parks District website, the first reports of toxic algae blooms occurred in 2014, in Lake Temescal and Lake Chabot (which still remains affected). Most likely, the recent California drought, and to some degree climate change in general, has been responsible for algal blooms forming at these lakes. And according to the website mywaterquality.ca.gov, Lake Anza has had recent cyanobacteria observed near the swim and dam areas - although no toxins have been reported.

The dog that prompted my report on this topic did very well, and suffered no long-term effects. Not all algae blooms contain toxins. Interestingly, as of 2016, no deaths in cats from cyanobacteria have been reported in veterinary literature - it is possible that cats are not sensitive to the toxin, or perhaps they generally don't like to swim!

Prevention involves avoiding or decreasing exposure to potential algal bloom toxins. This includes avoiding obvious algae scum areas, found most along a shoreline, washing dogs thoroughly after letting them play or swim in a lake or river. If you think your dog might have been exposed to blue algae toxins, it is warranted to seek immediate veterinary care.

The state of California has a very informative website with a California Harmful Algal Blooms Incident Reports Interactive Map https://mywaterquality.ca.gov/habs/where/freshwater_events.html.

Additional reading can be done at the East Bay Regional Park District website: http://www.ebparks.org/news/displaynews.htm?NewsID=246&TargetID=3.