Blue-Green Algae: A Veterinarian Reference

IDENTIFYING ILLNESS DUE TO BLUE-GREEN ALGAE

DESCRIPTION OF THE PROBLEM

Blue-green algae (also known as cyanobacteria) are non-pathogenic photosynthetic bacteria that grow in outdoor water bodies and produce toxins such as microcystins, cylindrospermopsin and anatoxin-a. They can grow quickly and form large blooms, especially in warm weather.

SCOPE OF THE PROBLEM IN CALIFORNIA

  • Toxic blooms occur throughout California and are increasing in number, frequency and severity.

  • Dog and livestock deaths in California have been linked to blue-green algal toxins.

EXPOSURE

Animals can be exposed to blue-green algae and its toxins by:

  • Contacting any infected water body including lakes, rivers, ponds, etc. Because animals are attracted to 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.
  • Consuming water and algae from residential pools or decorative ponds.
  • Ingesting blue-green algae health supplements.

CLINICAL SIGNS, DIAGNOSIS and TREATMENT: See the table below and https://mywaterquality.ca.gov/habs/resources/domestic_animals.html#res_vets. Limited funding may be available to cover physical examination of ill dogs with suspected poisoning.

BIOSPECIMEN COLLECTION, HANDLING and SHIPPING: For more details, see https://mywaterquality.ca.gov/habs/resources/domestic_animals.html#res_vets. Limited funding may be available to collect and analyze some of the suggested canine specimens.

REPORTING:  Reporting confirmed or suspected cases will help prevent other animal and human exposures to blue-green algal toxins. Please complete the Illness Information Section on the Report Form available at https://mywaterquality.ca.gov/habs/do/bloomreport.html. For questions call the State Water Resources Control Board at (844) 729-6466.

 

Blue-Green Algae Poisoning - Veterinary Reference
EXPOSURE HISTORY CLINICAL SIGNS DIFFERENTIAL DIAGNOSIS LABORATORY DIAGNOSTICS TREATMENT OPTIONS
Access to any outdoor water body up to 48 hours prior to onset of symptoms. Includes bays, lakes, rivers, streams, ponds, etc. Also includes residential pools and ponds containing algae.
Potential for ingestion of water or algal material (including dried material near shore or on land). Includes cleaning algae off fur.
Ingestion of blue-green algae health supplements.		 Hepatotoxin (microcystin)
Onset within minutes to days:
  • Vomiting, diarrhea
  • Lethargy, depression, anorexia
  • Jaundice, abdominal tenderness
  • Dark urine, tarry stools
 Acetaminophen overdose; rodenticide, mushroom toxin, aflatoxin and other hepatotoxin poisonings, other hepatopathy Elevated ALP, AST, ALT, GGT, bile acids, bilirubin
Coagulopathy
Hypoglycemia
Hypoproteinemia
Toxin present in clinical specimens†		 Remove access to contaminated water, clean fur
Emesis induction and oral activated charcoal slurry may be helpful
Oral cholestyramine has been effective up to 7 days post exposure‡
Cyclosporin A, rifampin and intravenous silibinin may be helpful*
Supportive therapy
Nephrotoxin, hepatotoxin (cylindrospermopsin)
Onset within minutes to days:
  • Similar to microcystin and
  • Excessive thirst
  • Increased urination
 NSAID overdose, ethylene glycol, grape/raisin ingestion, other nephrotoxin poisonings, other nephropathy or hepatopathy Similar to microcystin and
Proteinuria, glycosuria, hematuria
Elevated BUN and creatinine
Hypokalemia
Toxin present in clinical specimens†		 Remove access to contaminated water, clean fur
Emesis induction and oral activated charcoal slurry may be helpful
Supportive therapy
Neurotoxin
(anatoxin-a)
Within minutes to hours:
  • Ataxia
  • Seizures, paralysis
  • Respiratory arrest, sudden death
 Pesticide poisoning, mycotoxins penitrem A and roquefortine, other toxin poisoning, myasthenia gravis Toxin present in clinical specimens† (Anatoxin-a can be measured in serum and urine) Remove access to contaminated water, clean fur
Emesis induction and oral activated charcoal slurry may be helpful
Supportive therapy
Artificial ventilation
Skin contact with water bodies containing blue-green algae or toxins. Dermal toxins
Within minutes to hours:
  • Rash, hives
  • Allergic reaction
 Other dermal allergens   Remove algae and clean fur

†Stomach, rumen or GI contents, water and, for anatoxin-a only, serum and urine. See the following pages for details. Necropsy is encouraged when applicable.
‡ Rankin et al., 2013, Toxins, 5, 1051-63 (78.4 mg/lb, mixed with water, PO, q 24 h).
*Merck Veterinary Manual

Clinical Case Consultation

For additional assistance contact the ASPCA Animal Poison Control Center: (888) 426-4435. Available 24 hours/day, 365 days/year. There is a $65 consultation fee.

Technical information in this fact sheet was reviewed by veterinarians from the California Department of Public Health Veterinary Public Health Section, California Department of Food and Agriculture Animal Health Branch and CAHFS Toxicology Laboratory.

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