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Home , Cyanotoxin, Harmful algal bloom

Harmful Facts for Veterinarians

Cyanobacteria (Blue-green HABs in

Algae) have been found in lakes Cyanobacteria, commonly known as blue- everywhere in Minnesota, but are most green , are frequently found in common in warm, shallow, nutrient-rich freshwater systems. The prefer lakes often found in central and southern calm, sunny weather conditions, nutrient- Minnesota. Blooms usually occur during rich water, and water temperatures higher summer and early fall, but can occur other than 75° F. When conditions are right, the times of the year if conditions are right. bacteria can multiply rapidly, creating a is the primary bloom. Cyanobacterial blooms are often detected in Minnesota lakes. Other described as looking like pea soup or spilled , including anatoxin-a and green paint. They are often found on the have also been downwind side of a lake or in a secluded detected. bay or shoreline. Blooms are not always large and dense and can sometimes cover small portions of a lake with little visible Exposure algae. Blooms can also produce a swampy Animals can be exposed when they drink odor when the cells decompose. from, swim in, or lick fur or hair containing toxic water or algae. Animals are more likely than humans to be exposed because Cyanotoxins and Harmful they do not always avoid entering and Algal Blooms (HABs) ingesting green, foul-smelling water. Cyanobacteria can produce , called cyanotoxins that primarily affect the or nervous system. Exposure to cyanotoxins Clinical Features has been associated with illness in humans Symptoms and severity vary depending on and severe illness and death in animals, the and dose the animal was exposed most commonly dogs and cattle. While not to. Animal deaths related to microcystin all cyanobacterial blooms produce toxins, it and anatoxin-a exposure have been is impossible to tell if a bloom is toxic or not reported in Minnesota. See the table, just by looking at it. Because of their “Veterinary Reference for Cyanotoxin harmful impacts on health, cyanobacteria Exposures,” on page 3 for toxin-specific blooms are often referred to as harmful information. algal blooms (HAB).

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HARMFUL ALGAL BLOOM FACTS FOR VETERINARIANS Treatment Options Reporting There are no specific antidotes to these To better understand the incidence and toxins. Treatment is symptomatic and geographic distribution of HAB-related supportive. Inducing vomiting within the illnesses in Minnesota, we request first 2 hours of ingestion can help minimize veterinarians report suspected or clinically absorption of ingested toxins. Activated diagnosed cases of HAB-related illness to charcoal slurry may be useful to bind toxins the MDH Waterborne Diseases Unit. in the gut and reduce absorption. Liver Identification and reporting of animal cases function should be monitored, and animals can also help identify a toxic bloom and should be aggressively treated with fluids prevent future animal and human illnesses. and corticosteroids to support liver function and prevent shock. Neurologic symptoms The Veterinary HAB Reporting Form is may require seizure control and ventilator available at support. Case reports have suggested that https://www.health.state.mn.us/diseases/h cholestyramine may be effective at treating ab/vet/index.html. microcystin poisoning, but this treatment is Report cases by phone to 651-201-5414 or considered experimental. Milk thistle 1-877-676-5414 or by fax to 651-201-5743. (Silybum mariamum) has also been used intravenously for general liver protection; this is also experimental.

Prevention Measures There is no way to tell if a blue-green algal bloom is toxic just by looking at it. People and animals should avoid contact with water with blue-green algae. The risk of illness after a bloom goes away is low; however, toxins can persist in the water after the bloom has cleared up. Watch for signs of recent blooms, such as green scum on the shoreline and keep animals from eating debris that has washed up on the shore. Caution should always be taken when a bloom occurs. Advise your clients, “When in doubt, stay out.” Animals that go into water where a bloom may be should be washed off with immediately. If an animal becomes ill, veterinary care should be sought as soon as possible.

2 Veterinary Reference for Cyanotoxin Exposures

Toxin Exposure Onset to Likely Symptoms Differential Diagnosis Possible Laboratory or Other Route Symptoms Findings Hepatotoxins Ingestion Minutes to • Acute depression • Acetaminophen • Elevated bile acids & liver enzymes days • Weakness & • Nonsteroidal anti- • Hypoglycemia incoordination inflammatories • Hyperkalemia • Loss of appetite • Aflatoxin • Proteinuria • Excessive drooling • Mushrooms • Prolonged clotting times • Vomiting & diarrhea • Sago/cycad palm • Presence of toxin in biological • Abdominal tenderness • Metals: copper, zinc, iron specimens (liver, stomach contents, • Jaundice • Xylitol (dogs only) stool) collected from animals that • Dark urine • Rodenticides became ill • Other hepatotoxins • Blue-green staining of fur or hair Ingestion Minutes to • Excessive drooling • Organophosphates • Presence of toxin in biological Anatoxin-a hours • Apprehension & • Carbamates specimens (stomach contents, urine, Anatoxin-a(s) anxiousness • Chlorinated hydrocarbon serum) collected from animals that became ill • Vomiting • • Blue-green staining of fur or hair • Muscle twitching • Metaldehyde • Seizures • Mushrooms • Respiratory failure • Other neurotoxins

Dermatotoxins Skin contact Minutes to • Rash • Other dermal allergens • Blue-green staining of fur or hair hours • Hives Lyngbyatoxin-a • Allergic reaction

Notes: Information about health effects from exposure to cyanobacteria and toxins is derived from reports of animal poisonings. For more information, see the Merck Veterinary Manual.

Minnesota Department of Health Waterborne Diseases Unit PO Box 64975 St. Paul, MN 55164 651-201-5414 or 1-877-676-5414 www.health.state.mn.us 1/2020 To obtain this information in a different format, call: 651-201-5414.

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