Cyanobacterial Poisoning in Animals

Study Notes

Algal poisoning in domestic animals and wildlife is primarily caused by cyanobacteria found in freshwater ecosystems globally.
Clinical signs vary based on specific cyanotoxins involved and can impact multiple body systems.
Diagnoses rely on exposure history, clinical signs, and necropsy findings; however, identifying specific cyanotoxins is essential for confirmation and treatment optimization.
Early gastrointestinal tract decontamination is crucial in managing affected animals.

Cyanobacteria, also known as blue-green algae, are ancient prokaryotes that live in freshwater, brackish water, and soil.
They play a vital role in the ecology of lakes and ponds and are omnipresent in freshwater systems.
Toxigenic cyanobacteria proliferation results in freshwater harmful algal blooms (FHABs), affecting local ecosystems through oxygen depletion and toxin production.

FHABs pose a global issue, particularly in regions with limited freshwater resources, impacting water security.
Cyanobacteria produce numerous bioactive compounds harmful to humans, animals, and wildlife.
Over 40 genera of cyanobacteria have documented toxic potential, and their blooms have been increasing due to human-induced ecological changes.
Climate change, elevated water temperatures (over 20°C), and nutrient pollution from phosphorus and nitrogen contribute to the rise of FHABs.

A notable FHAB event occurred in Toledo, Ohio, in 2014, contaminating the city's water supply with microcystin.
Most toxic responses result from direct ingestion of cyanotoxins present in affected water or organisms.
Common cyanotoxins include microcystins, anatoxins, guanitoxin, saxitoxins, and cylindrospermopsins, each causing various health issues in animals.

Microcystins are prevalent hepatotoxins that cause acute liver failure and hepatocellular necrosis.
Cylindrospermopsins, known to bioaccumulate in aquatic organisms, cause gastroenteritis, hepatic and renal necrosis, oxidative stress, and DNA damage.
Anatoxins exhibit neurotoxic effects and can result in muscle stimulation, tremors, seizures, and respiratory paralysis.
Guanitoxin affects cholinesterase and results in symptoms like salivation, diarrhea, and vomiting.
Saxitoxins may lead to lethal concentrations and are known for causing paralytic shellfish poisoning.
Emerging toxin BMAA is linked to chronic neurological damage, though the significance remains debated.

Aetokthonotoxin, produced by cyanobacteria on invasive Hydrilla verticillata, leads to vacuolar myelinopathy, mainly affecting birds such as coots and bald eagles that feed on contaminated waterfowl.

Podcast