Cyanotoxin FAQ

A: Exposure to cyanobacterial blooms in recreational water (e.g., lakes, rivers, ponds) has reportedly lead to allergic reactions, including hay fever-like symptoms; skin rashes; and pulmonary and gastrointestinal distress (diarrhea, vomiting, and stomach pain). Animals that swim in contaminated recreational water can be at risk for serious health effects or even death.

A: Animals are extremely sensitive to cyanotoxins and can become very ill or potentially die due to exposure at very low levels. The primary route of exposure to these toxins is through ingestion. Ingestion occurs when pets and wildlife drink water from a cyanobacteria-filled lake or pond, lick their fur after swimming, or eat dried cells that accumulate along the shoreline. Because dogs are cyanotoxin sensitive animals and dog deaths have been confirmed due to CyanoHABS, Oregon Health Authority developed dog-specific Recreational Use Values (RUVs) for cyanotoxins in recreational water (Table C-4)

Table C-4. Dog-specific RUVs for cyanotoxins (ug/l)

Dog RUV	Anatoxin-a	Cylindrospermopsin	Microcystin	Saxitoxin
	0.4	0.4	0.2	0.02

OHA does not use these dog-specific RUVs as the basis for public health advisories. Rather, they’re offered as a resource to veterinarians and veterinary associations to use as appropriate, when treating dogs believed to have been exposed to cyanotoxins. OHA will use these values and potential exposure scenarios in discussions with individual veterinarians or pet owners, to educate them on the vulnerability of pets to cyanotoxin exposure. Contact OHA for details about the origin of these dog-specific values.

Note: Pet owners should be aware that the RUVs for dogs is below the Guidance Values for drinking water affected by cyanotoxins. Because of this, OHA recommends owners supply their pets with bottled water or water from alternative sources when a drinking water advisory is in place.

Reference: Advisory Guidelines for Harmful Cyanobacteria Blooms in Recreational Waters, (page 22)

A: Most camping and home water filters and purifiers will not remove these toxins from drinking water. Only reverse osmosis treatment units, and special carbon treatment units certified to remove microcystins (under NSF P477) are known to be effective. Carefully read the manufacturer’s instructions to determine what type of process is used.

A: If you, family members or your pet comes in contact with a cyanobacterial bloom, wash yourself and your pet thoroughly with fresh water. If you are concerned about your health, the health of a family member, or the health of your animal, contact your health care provider, a Poison Center, or a veterinarian. Call a veterinarian if your animal shows any of the following symptoms of cyanobacteria poisoning: loss of appetite, loss of energy, vomiting, stumbling and falling, foaming at the mouth, diarrhea, convulsions, excessive drooling, tremors and seizures, or any other unexplained sickness after being in contact with water. Tell your veterinarian that your animal has been in water that may have a cyanobacterial bloom. 

A: Reducing nutrient pollution, such as excess nitrogen and phosphorus, is essential to reducing the formation of cyanobacterial blooms. Things you can do to reduce nutrients in your local waterways include:

Use only the recommended amounts of fertilizers on your yard and gardens to reduce the amount that runs off into the environment.

Properly maintain your household septic system.

Maintain a buffer of natural vegetation around ponds, lakes, and other waterbodies to filter incoming water and stop fertilizing within 20 feet of the waterbody.

Do not add fertilizers when the ground is frozen.

Do not apply fertilizer immediately before or during rain and snow.

Pick up pet waste and dispose of properly.