Preventing Pet and Livestock Illnesses Caused by Harmful Algal Blooms

Apr. 8, 2024

Harmful algal blooms can be deadly for pets and livestock.
Animals can get sick and die within hours after swallowing toxins made by harmful algae.
Protect your pets and livestock by keeping them away from water that looks or smells bad.

Smiling woman holding a dog with a river in the background

Overview

Cyanobacteria (also called blue-green algae) are microscopic organisms that can be found naturally in all types of water.

Sometimes cyanobacteria rapidly grow out of control, or bloom. Some of these blooms produce toxins (poisons) that make people and animals sick. Cyanobacterial blooms are most commonly found in fresh water, such as lakes, rivers, and streams.

Rocky lake shore with green water washing up. — Cyanobacteria can change the color of the water or look like foam, scum, mats, or paint on the surface of water.

Keep Reading How to Recognize a Harmful Algal Bloom

Exposure

Pets and livestock can get very sick and die within hours to days after swallowing cyanobacterial toxins. The toxins can be in the cyanobacteria or in the water.

Keep Reading How People and Animals Get Sick From Harmful Algal Blooms

Prevention steps and strategies

If you think there is a cyanobacterial bloom in the water, do not let your pets or livestock do any of the following:

Illustration of a sheep drinking green water with algae. A red line through the illustration indicates that your animals should not drink this type of water. — Do not let your animals drink the water.

Illustration of a dog swimming in green water with algae. A red line through the illustration indicates that your animals should not go in this type of water. — Do not let your animals swim or play in the water.

Illustration of a cow eating grass right next to green water with algae. A red line through the illustration indicates that your animals should not eat near this type of water. — Do not let your animals eat near the water.

Illustration of a dog eating a dead fish on the shore of a green body of water with algae in it. A red line through the illustration indicates that your animals should not eat dead animals in or near waterbodies. — Do not let your pets or livestock eat dead animals (like fish) washed up on the shore.

Illustration of a dog eating algae near a body of water. A red line through the illustration indicates that your animals should not eat algae. — Do not let your animals eat algae.

Illustration of a dog licking green water from its fur. A red line through the illustration indicates that your animals should not lick their fur after being in discolored water. — If your animal does go in the water, do not let them lick their fur afterward.

If your animal goes in or near the water

If your pets or livestock go in water with a possible cyanobacterial bloom, immediately wash them off with clean water to keep them from licking cyanobacteria off their fur.

Call a veterinarian if your animal shows any of these signs:

Loss of energy
Loss of appetite
Vomiting
Stumbling or falling
Foaming at the mouth
Diarrhea
Convulsions
Excessive drooling
Tremors and seizures
Any unexplained sickness that occurs within a day or so after being in contact with water.

Resources

Call your local poison control center at 1-800-222-1222 if you have questions about cyanobacterial toxin poisoning.

Call the ASPCA Animal Poison Control Center at 1-888-426-4435 or the Pet Poison Helpline at 1-855-764-7661 if you have questions about your pet or livestock. (Note: There is a fee for these calls.)

Report cyanobacterial blooms or illnesses to your health department online or by phone.