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Harmful Algal Bloom-Related Illness Information for Veterinarians
On this page:
Disease Reporting
Clinical Features
Treatment
Laboratory Tests
Fact Sheet for Veterinarians
Resources for Veterinarians
Disease Reporting
To better understand the incidence and geographic distribution of harmful algal bloom (HAB)-related illnesses in Minnesota, the Minnesota Department of Health (MDH) requests veterinarians report suspected cases of HAB-related illness to the MDH Waterborne Diseases Unit. Illness in animals is often the first sign that a toxic bloom is present in a waterbody due to their smaller size and behavior. Identification and reporting of animal cases can help identify a harmful algal bloom and prevent future animal and human illnesses.
How to report HAB-related illnesses
- Veterinary Harmful Algal Bloom (HAB) Case Report Form (PDF)
For all animal cases, please fill out this form. Fax completed form to 1-800-233-1817. - Phone
Illnesses may be reported by phone to 651-201-5414 or 877-676-5414.
Clinical Features
Clinical features depend on the type of toxin and route of exposure.
| Toxin | Exposure Route | Onset to Symptoms | Likely Symptoms |
|---|---|---|---|
| Hepatotoxins Cylindrospermopsins Microcystins Nodularins | Ingestion | 1 to 2 hours, or more | Acute depression Weakness & incoordination Loss of appetite Excessive drooling Vomiting & diarrhea Abdominal tenderness Jaundice Dark urine |
| Neurotoxins Anatoxin-a Anatoxin-a(s) Saxitoxins | Ingestion | Minutes to hours | Excessive drooling Apprehension & anxiousness Vomiting Muscle twitching Seizures Respiratory failure |
| Dermatotoxins Lyngbyatoxin-a Aplysiatoxin | Skin contact | Minutes to hours | Rash Hives Allergic reaction |
Treatment
- There are no specific antidotes to these toxins.
- Treatment is symptomatic and supportive.
- Inducing vomiting within the first 2 hours of ingestion can help minimize absorption of ingested toxins.
- An activated charcoal slurry may be useful to bind toxins in the gut and reduce absorption.
(1: Merck Veterinary Manual) - Liver function should be monitored, and animals should be aggressively treated with fluids and corticosteroids to support liver function and prevent shock.
- Neurologic symptoms may require seizure control and ventilator support.
- Case reports have suggested that cholestyramine may be effective at treating microcystin poisoning, but this treatment is considered experimental.
(2: Treatment of cyanobacterial (microcystin) toxicosis using oral cholestyramine) - Milk thistle (Silybum mariamum) has also been used intravenously for general liver protection; this is also experimental.
(3: Milk thistle and its derivative compounds)
The Merck Veterinary Manual. “Pet Owner Version, Algal Poisoning.” Last modified Sept. 2024.
Rankin KA, Alroy KA, Kudela RM, Oates SC, Murray MJ, Miller MA. Treatment of cyanobacterial (microcystin) toxicosis using oral cholestyramine: case report of a dog from Montana. Toxins (Basel). 2013;5(6):1051-1063.
Hackett ES, Twedt DC, Gustafson DL. Milk thistle and its derivative compounds: a review of opportunities for treatment of liver disease. J Vet Intern Med. 2013;27(1):10-16.
Laboratory Tests
If you suspect your client is experiencing a HAB-related illness or died from a HAB-related illness, please contact the Minnesota Department of Health at 651-201-5414 or 877-676-5414 for possible testing options.
Fact Sheet for Veterinarians
- Harmful Algal Bloom Facts for Veterinarians (PDF)
Information provided includes general HAB facts, symptoms, differential diagnoses, possible laboratory findings, and treatment options.
Resources for Veterinarians
 | Suspect Illness is Due to Harmful Algae? Harmful Algal Bloom Magnet (PDF) Printable template for magnet or card |