Department of Environmental Quality

Keeping Dogs and Animals Safe from Harmful Algae

A person kissing their dog's cheek, outdoors kneeling down on a trail.

Pet owners


A veterinarian in scrubs and a mask, at an exam table with a corgi dog.

Veterinarians


A black lab hunting dog outdoors with a duck in its mouth. Keep your dog safe while waterfowl hunting

Waterfowl hunters


There are two types of harmful algae that dog-owners should be aware of

1

Harmful algal blooms (also known as HABs, blue-green algae, and cyanobacteria)

2

Harmful algae mats (also known as benthic mats)

Both types of harmful algae can produce dangerous toxins that can cause serious illness or death in dogs. Learn how to identify the two types of harmful algae.

What will harmful algae do to my dog?

Harmful algae (or cyanobacteria) are microscopic organisms naturally present in reservoirs, lakes, rivers, streams, and wetlands. Animals are at high risk for getting sick from harmful algae and more likely to come in contact with or drink the water. Toxins produced by harmful algae can be fatal for dogs.

Animals are often exposed to harmful algae by:

Drinking contaminated water

Dog drinking water from a stream or shallow body of water outdoors. Be careful about letting them drink from algae contaminated water.

Eating harmful algae mats

Dog drinking or eating something from a puddle/stream outdoors. Prevent animals from eating harmful algae mats.

Licking harmful algae from their fur

Dog licking its paw, outdoors.

If your dog comes into contact with harmful algae, rinse your dog with fresh water as soon as possible. Monitor for symptoms of harmful algae-associated illness in your dog.

Symptoms

These symptoms may differ depending on how and for how long your dog was exposed to harmful algae, and can include:

Direct skin contact or inhalation:

  • Skin rash
  • Skin hives
  • Allergic reactions

Ingestion:

  • Excessive drooling
  • Vomiting
  • Diarrhea
  • Foaming at the mouth
  • Stumbling
  • Loss of appetite
  • Difficulty breathing

Symptoms can appear minutes to days after harmful algae exposure. If an exposed dog displays symptoms, contact emergency veterinary care immediately.

If you believe your dog has been exposed to harmful algae:

  • Wash your dog with clean water immediately
  • Contact your veterinarian
  • If your dog is displaying symptoms of harmful algae exposure, seek emergency veterinary care 

You can also call ASPCA Animal Poison Control Center at (855) 764-7661 or Pet Poison Control Helpline at (801) 536-4123 for exposure-related questions. NOTE: there is often a $90-100 fee for these calls.

How do I know if a waterbody is safe for my dog?

You can check harmful algae waterbody advisories during recreational monitoring season. Even if there is no advisory for a particular waterbody, conditions can change rapidly, making it important for dog owners to learn how to identify harmful algae. Harmless filamentous green algae and duckweed are common in these environments, and may be mistaken for harmful algae–learn how to tell the difference between harmful algae and harmless aquatic vegetation.

If you suspect harmful algae may be present, keep dogs away from the water!

Do rapid water self-test kits work for detecting harmful algae?

Rapid kits or self-tests for harmful algae do not use methods approved by the U.S. EPA and may not accurately detect toxins. The best way to protect your dog is to know how to visually recognize harmful algae.


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