Health & vet care
Blue-Green Algae Poisoning in Dogs: What to Do Now
If your dog has been in, near or drinking from water with algae, scum or foam, call your vet or the nearest emergency vet immediately, even if your dog seems fine. Blue-green algae poisoning can be rapidly fatal and has no antidote. You can also call ASPCA Animal Poison Control at (888) 426-4435 or Pet Poison Helpline at (855) 764-7661; a fee may apply. Do not delay getting to a vet.
By Matt GarnettUpdated November 13, 20263 min read2 sources
What to do right now
Call your vet or the nearest emergency vet immediately and tell them your dog may have been exposed to blue-green algae, so they can prepare. Cornell University's veterinary college advises rinsing your dog's fur with fresh water, calling a pet poison hotline and going to a veterinary hospital right away. The CDC gives the same rinse-off advice if an animal has been in water with a bloom.
Do not wait for signs to appear, and do not try to make your dog vomit at home unless a vet tells you to. Note where and when your dog was in the water and roughly how long. Cornell also asks owners who suspect a bloom to alert the local or state health department, which can warn other people and pet owners.
What blue-green algae is and how to spot it
Blue-green algae are really cyanobacteria, a type of bacteria that can overgrow in fresh water, most often in stagnant lakes and ponds. Some produce toxins. Cornell names the two most serious as microcystin, which mainly harms the liver, and anatoxin, which mainly affects the nervous system. The CDC adds that blooms are more likely in warm, slow-moving water rich in nutrients.
A bloom may look blue-green or red-brown, and can appear as mats, foam, scum or even paint on the surface. The water may smell like rotting plants. The CDC notes some blooms grow underwater and are hard to see, and Cornell is clear that you cannot judge a bloom safe or unsafe by its appearance. When in doubt, stay out.
Signs and how fast they appear
According to Cornell, signs can appear rapidly or over several hours, depending on the toxin. They include vomiting, diarrhea, drooling, weakness, pale gums, collapse, muscle tremors, difficulty breathing, muscle rigidity, paralysis, seizures and sudden death. The CDC warns that animals can become seriously ill or die within hours of contact.
Any of these signs after your dog has been near water is an emergency, so go to a vet at once. But a dog that looks normal can still have been exposed, which is why the first step is a phone call, not a wait-and-see.
What your vet will do
There is no specific antidote for the toxins. Cornell says treatment is intensive supportive care, which can include IV fluids, oxygen, anti-seizure medication, electrolytes and glucose, and blood products. Diagnosis starts with the signs and your dog's history of water exposure, and vets may test the water and run bloodwork to check for organ damage.
Early treatment is critical. Cornell reports that many exposed dogs die before reaching a hospital, that those who arrive often need intensive care and hospitalization, and that survivors of liver-toxin exposure may develop chronic liver disease. That is why speed matters more than certainty about the cause.
How to prevent it
Avoid letting your dog drink from, walk in or swim in water with visible algae, scum or foam, or water that smells bad. Check local advisories before visiting a lake or pond, and keep your dog on a leash near water if you cannot be sure. Cornell also suggests removing standing water around the home, such as plant saucers, birdbaths and fountains, to reduce bloom growth.
If your dog does go into suspicious water, rinse its fur with fresh water right away and call your vet, even when no signs have appeared yet. This page is general information, not veterinary advice, and it cannot replace an examination by the vet who knows your pet.
Common questions
Can dogs survive blue-green algae poisoning?
Some do, especially when treated early, but Cornell says many exposed dogs die before reaching a hospital and there is no antidote. Call a vet immediately after any suspected exposure.
How long after swimming do blue-green algae signs appear?
Cornell says signs can appear rapidly or over several hours, and the CDC says animals can become seriously ill or die within hours, so do not wait for signs before calling your vet.
How can I tell if a pond has toxic algae?
You cannot tell by looking. Cornell says appearance alone cannot show whether a bloom is toxic, so avoid water with scum, foam, mats, discoloration or a bad smell, and check local advisories.
Should I rinse my dog after swimming in algae water?
Yes. Cornell and the CDC both advise rinsing with fresh water right away, then calling your vet. Rinsing does not make it safe to wait, because toxins may already have been swallowed.
Sources we checked
This guide is general information, not veterinary advice. If your pet is unwell or injured, contact your veterinarian.