Pets, Livestock, and HABs

FAQs for Dogs

How can dogs be exposed to freshwater HABs?

Animals can be exposed to freshwater harmful algal blooms (HABs) and associated cyanotoxins through: dog_an_stick

  • Skin contact or ingestion at any affected water body including lakes, rivers, or ponds, as well as residential pools or decorative ponds. Because animals are attracted to cyanobacteria (blue-green algae), they drink the water and eat algal material. Dogs in particular lick algae caught in their fur after being in the water.
  • Inhalation of airborne droplets or mist containing cyanobacteria and cyanotoxins.
  • Ingestion of blue-green algae health supplements.

How can I keep my dog safe from freshwater HABs?

  • Check if a waterbody has a reported bloom by checking the HAB Reports Map, contacting the waterbody manager, and looking for posted advisory signs.
  • Check to see if the water has a scum, algal mats, or is discolored.
  • Do not let your dog drink, wade, or swim in HAB-affected water.
  • Do not let your dog eat scum or algal material.
  • Wash your pets with clean water after lake or river play. Provide clean drinking water.

What are signs of possible cyanobacterial toxin poisoning in dogs?

Animals can become sick within minutes to days following exposure to cyanotoxins.

Contact a veterinarian if your animal shows any of these signs:

  • Loss of energy
  • Loss of appetite
  • Vomiting
  • Stumbling and falling
  • Foaming at the mouth
  • Diarrhea
  • Convulsions
  • Excessive drooling
  • Tremors and seizures
  • Dermal irritation or rash
  • Any unexplained sickness that occurs within a day or so after being in contact with water

The Office of Environmental Health Hazard Assessment (OEHHA) has developed a fact sheet for veterinarians on recognizing, diagnosing and treating animals for exposure to blue-green algae. For additional assistance, contact the 24-hour ASPCA Animal Poison Control Center hotline at (888) 426-4435. A $65 consultation fee may be applied.

See the HAB-related Illness Tracking webpage for information on previously reported dog illnesses related to freshwater HABs in California.


FAQs for Livestock and Other Large Animals

cow in stream

How can livestock or other large animals be exposed to HABs?

Livestock can be poisoned by ingestion of algal material either in the water or as dried mats on the shore, or from drinking water where algal decay has released considerable toxins into the water. Sheep are more likely to be affected than cattle because they tend to drink from the edges while cattle often wade into the waterbody. Ingestion of blue-green algae supplements can be a potential source of cyanotoxins.

How can I keep my livestock and other large animals safe from HABs?

Livestock water supplies should be checked daily in summer and autumn for algal blooms. Treat all algal blooms as possibly toxic to livestock and prevent animals from accessing them unless the algae are identified and the level of toxin determined. Avoid administering blue-green algae supplements unless they are shown to be free of cyanotoxins.

What are signs of possible cyanobacterial toxin poisoning in livestock or other large animals?

Poisoning will depend on the levels of cyanotoxin that are present and ingested, the susceptibility of the livestock, and the amount of food in the animal’s gut, which will help counter the effect of the toxin. All animals are at risk of poisoning from cyanotoxins. In North America, cyanotoxin poisonings in cattle, horses, sheep, pigs, chickens, and turkeys have been reported.  Most of the poisonings were fatal and were associated with visible scum of cyanobacteria. In 2017, a large cattle mortality event at a reservoir in southeastern Oregon resulted from exposure to microcystin (Dreher et al., 2019). More information is available from the Western Australia Government webpage on livestock poisoning from algal blooms. See the HAB-related Illness Tracking webpage for information on previously reported livestock illnesses related to HABs in California.

Resources for Veterinarians

Resources are available to assist veterinarians to respond to incidents of suspected HAB-related illness in animals.  The California Water Boards provide limited funding for confirmatory testing of HAB-related poisonings in canines, and can assist with HAB identification and early response in suspected exposure areas.  State or local agencies can post advisory signs at hazardous waterbodies to prevent additional animal poisonings.

CLINICAL SIGNS, DIAGNOSIS and TREATMENT: Rapid diagnosis, decontamination, and aggressive and rapid treatment is critical, particularly for significant liver symptoms. See the 2017 Veterinarian Reference and Bates (2018) review on Cyanobacteria (blue-green algae) exposure in dogs. A case report of successful treatment of microcystin toxicity using oral cholestyramine is provided by Rankin et al. (2013).

  • POTENTIAL FUNDING: Limited funding may be available to cover physical examination and sample analysis of ill dogs with suspected poisoning. If funding is approved by the Water Boards, funds can only reimburse California licensed veterinarians for testing. A list of the potential testing costs that can be reimbursed is listed below:
  • live canine physical examination
  • canine necropsy at your clinic
  • cyanotoxin analysis
  • canine clinical specimen collection (vomit, stomach contents, serum, urine, liver, and/or kidney)
  • specimen shipment to an analytical laboratory approved by the Water Board

Apply for reimbursement by completing the Illness Information Section of the HAB Portal bloom incident form.

REPORTING: Reporting confirmed or suspected cases will help prevent other animal and human exposures to cyanobacterial toxins. Please complete the Illness Information Section on the Freshwater Bloom Incident Report Form. See the HAB-related Illness Tracking webpage for information on previously reported animal illnesses related to HABs in California.


Online Toolkit

protect your pets imageThe following resources are available for printing and distribution. Contact for limited hard copies or to request other resources of interest.

For general information on HABs please refer to the HABs FAQ webpage