Blue-Green Algae and Dogs: Signs, Risks, and What to Do

What is blue-green algae?

Blue-green algae is not actually algae. It is a type of bacteria called cyanobacteria. It thrives in warm, nutrient-rich water and can form dense clusters called blooms. Blooms often occur during warmer months. They can grow quickly when nutrients are abundant, including runoff from fertilizers or animal waste.

Water affected by cyanobacterial blooms may appear green, blue, yellow, red, or brown, often with a thick mat of green or blue-green scum on the surface. The water can look similar to spilled paint or pea soup, and sometimes the blooms produce a swampy odor.

What Does Blue-Green Algae Look Like?

Blue-green algae can be difficult to identify. Cyanobacteria may not be visible unless they clump together or form a bloom, and you cannot tell whether a bloom is toxic just by looking at it. When in doubt, keep your pet out of the water.

Blue-green algae blooms can appear green, blue, yellow, red, or brown. The water may have a thick mat of scum on the surface and can look like spilled paint or pea soup. Some blooms also produce a swampy odor.

When in doubt, keep your pet out of the water.

What Are Blue-Green Algae Poisoning Signs in Pets?

Blue-green algae poisoning is also called cyanobacterial toxicosis. Signs can develop quickly, often within 15 minutes to several hours after exposure. The primary toxins are microcystin and anatoxin, which pose severe health risks to pets. Microcystin can cause severe liver damage. This can lead to liver failure and death within hours to days. Anatoxin affects the nervous system. It can cause neurologic signs, including seizures, excessive salivation, and rapid death.. Both toxins can cause shock, respiratory arrest, and rapid death.

Initial signs can vary, but commonly include:

• Vomiting
• Diarrhea
• Drooling
• Weakness
• Pale gums

As the condition progresses, more severe signs, such as muscle tremors, difficulty breathing, paralysis, and seizures, may develop.

What Should I Do If My Pet Has Been Exposed to Blue-Green Algae?

If you suspect your pet has been exposed to blue-green algae, rinse them with fresh, clean water to remove any algae from their fur and ensure they do not lick and ingest the toxic bacteria. If your pet has poisoning signs, such as vomiting, diarrhea, or disorientation, or you know they have consumed contaminated water, seek immediate veterinary care.

How is Blue-Green Algae Poisoning Treated in Pets?

Since no specific antidote is available for cyanotoxins, supportive care is vital. Treatment may include:

• Decontamination — Your veterinary team may induce vomiting, perform gastric lavage, or give activated charcoal to help limit toxin absorption.
• Intravenous (IV) fluids — Your veterinary team may give IV fluids to treat dehydration and help maintain blood pressure.
• Oxygen therapy — Pets in respiratory distress may need oxygen support.
• Blood products —Pets with internal bleeding or shock may need whole blood or fresh frozen plasma.

Throughout the treatment process, continuous monitoring and adjustments based on your pet’s therapy response and progression of clinical signs are essential. Immediate and aggressive treatment increases the chances of recovery, highlighting the importance of quick action and specialized care in blue-green algae poisoning cases.

How can I prevent my pet from getting blue-green algae poisoning?

Prevention is the best way to protect pets from blue-green algae:

• Avoiding stagnant waters — Don’t let your pet drink or swim in stagnant ponds, lakes, or discolored bodies of water with bluish-green scum, foam, or algal blooms on the surface or edges.
• Providing water — Always bring clean, fresh water for your pet, especially when outdoors or hiking. This can discourage them from drinking from natural water sources.
• Rinsing after swimming — If your pet swims in natural water, rinse them thoroughly with clean water afterward. This helps remove algae from their fur.
• Using life jackets and leashes — Have your pet wear a life jacket near water. Keep them leashed so you can guide them away from dangerous areas.
• Watching for warnings — Local health departments may test water and post signs when conditions are unsafe. Always check for warnings and monitor local advisories before allowing your pet near water.

These steps can help reduce your pet’s risk of blue-green algae exposure. However, always err on the side of caution—if you are unsure about quality, keep your dog out of the water. If you suspect blue-green algae poisoning in your pet after swimming, contact your AAHA-accredited veterinarian for help.