At the Sequoia Humane Society, we often get calls from people who have heard that it is not safe to let their dogs swim in local lagoons. They want to know why, and if it is true.

The problem is that Blue Green Algae (BGA) in local rivers and lagoons can produce toxins powerful enough to kill a dog in hours, if not minutes. According to a Fact Sheet prepared by Harriet Hill of the Humboldt County Division of Environmental Health (April 2004), in the last three years eight dogs have died of suspected BGA poisoning after swimming in Big Lagoon or the South Fork of the Eel River.

BGA are actually a family of bacterial organisms, some of which produce deadly toxins that poison the nervous system (cyanobacteria), the liver (hepatotoxins), or cause allergic responses (lipopolysaccharide endotoxins). BGA neurotoxins can paralyze respiratory muscles and kill a dog within a few minutes. Hepatotoxins cause blood to pool in the liver causing death within hours.

Protecting your pet from these hazards is complicated. Though it is nearly impossible to predict when BGA will bloom, blooms are more likely to occur when water is warm but not hot, wind is mild, and the water contains nutrients from agricultural or urban runoff. Before letting your dog near any body of water, inspect it for signs of BGA bloom. Floating mats of BGA can vary in color. They can be blue-green, olive green, grey green, yellow-brown, or purple to red. Sometimes currents and winds push the algae to the shoreline where it can be difficult to identify. Even after a bloom disappears, toxins can be present in the water for up to three weeks and it can take only a few ounces of tainted water to kill a pet. Unless you visit an area frequently to monitor algae activity, you can't be sure the water is safe.

Protect your pet by never allowing him to wade, swim in, or drink water where you can see algae. If your dog accidentally ventures into algae infested water, rinse him off with clear running tap water immediately and watch for symptoms of BGA toxin poisoning. Symptoms may include stumbling and falling, inability to get back up, elevated heart rate, vomiting, foaming of the mouth, tremors, howling, loss of bowel control, eyes rolling back into the head or seizures.

BGA toxins are harmful to people, too, but we generally avoid swimming in algae. Dogs and young children are not so selective. They need you to keep them safe.

If you notice an algal bloom, or if your pet falls ill or dies following contact with water, you can help save the lives of other animals by reporting it promptly to the Humboldt County Environmental Health Division (268-2210).