Toxic Algae is a Real Danger to Dogs and Pets


Learn how to keep your family members & pets safe from toxic algae contamination & what to do in case of algal toxin poisoning.

In this Article


Are all algae blooms toxic to pets?

Danger of toxic algae for dogsNo. Most algae blooms are simple green or string algae and not harmful, but some blooms are actually a type of cyanobacteria that have the ability to produce toxins. When this toxic cyanobacteria (aka blue-green algae) is active, scientists and policy makers refer to them as harmful algal blooms (HABs).

Unfortunately, it is impossible to tell visually, by taste or odor whether a bloom is toxic.


What causes HABs?

While many factors contribute to HABs forming, the primary reasons include:

  • Still / low-flow water
  • Warm temperatures
  • Abundance of direct sunlight
  • Excess nutrients, primarily nitrogen & phosphorus.

HABs do occur naturally, but the frequency and severity is heavily influenced by human kind.


When do HABs Occur?

dogs-algae-bloom-harmful HABs typically occur in the late summer and early fall when temperatures are highest and water levels are lowest.   HABs are most likely to appear during periods of warm, sunny and calm conditions directly following a rain storm.

As rain water passes through our storm drains and back into the water ways, it carries sewage & waste water discharges as well as the residuals from fertilizers, animal manure, and failing septic tanks. Add in a sunny day and slow water and you have the perfect recipe for an HAB!


How will I know if an HAB is Happening?

Unfortunately, it is impossible to tell visually, by taste or odor whether a bloom is toxic. In cases of extreme blooms, local agencies will typically place signs up around the waterway, but you should always check with your local, State and Federal agencies for a forecast of HABs and to learn about active blooms to stay away from.

In cases when toxin concentrations are unknown pet owners should err on the side of caution and keep their dogs out of the water when suspicious looking blooms appear. Only after water samples have been taken and analyzed can we be certain of the presence of toxins.


How to Treat a Dog Who Appears Ill from Blue Green Algae Toxins

Call the veterinarian immediately! Unfortunately there is no antidote for the toxins produced by blue-green algae or cyanobacteria. Call the Pet Poison Helpline (800-213-6680) or the ASPCA (888-426-4435) for immediate help. Consultation fees apply.

Since death generally follows within days as a result of liver failure, treat every bloom as if it has toxins. Dogs are especially vulnerable to these waters because of their innate behavior to lap around a body of water. They are also attracted to the smell, which makes leashing very important.

Hunting dogs are especially predisposed due to increased exposure outdoors.

A pet is like part of the family, especially a dog. Losing a pet can feel like losing a child or a long time companion. Keeping them safe is a priority, so if you live on a big property be careful of where you let your dog/pets play.

Keep your dog leashed while around suspected waters. If you use fertilizers, try to keep the area where they are used contained. To be safe, only let your dog/pets drink clean tap water.

“The first recorded episode of animal poisoning attributable to cyanobacteria occurred in Australia in 1878.” Source


Prevention is Your Best Method for Reducing Toxin Risk

If possible keep your dog on a leash near shorelines, don’t let dogs wade, drink the water or eat/walk in beach debris. If you dog goes in the water remove them immediately. Don’t let them lick their fur or paws after getting out of the water until you can thoroughly rinse/wash them from a safe freshwater source.

Use a towel or rag to remove algal debris. (Use rubber gloves if possible) Remember to wash your own hands with fresh water, look closely for any symptoms and notify the public health department or state natural resource management agency if you observe a suspected harmful algae bloom.


Animal Symptoms from Harmful Algae Toxins

  • Lethargy
  • Weakness
  • Pale Mucous Membranes
  • Disorientation
  • Excessive Salivation and Tear Production
  • Muscle Tremors
  • Muscle Rigidity
  • Paralysis
  • Seizures
  • Respiratory Distress
  • Vomiting
  • Diarrhea
  • Bloody, Black, or Tarry Stool
  • Jaundice
  • Shock
  • Coma
  • Death

Sad But Recent Algae Bloom Incidents with Dogs

“It is likely that the number of deaths is much higher than the 200+ that have been reported. Due to the wide range of symptoms that can be caused by numerous other factors, many might believe there was another cause of toxicity.” Source

“The dog owner reported that after playing in the water, and probably drinking some, it started to exhibit strange behavior within 45 minutes including lethargy and vomiting. The dog passed away shortly after that.” Source

“Our message to dog owners and to parents is when in doubt, stay out,” Skuta said. “If you see a crummy situation on a lake, even if it’s not the obvious pea-soup paint kind of look, better safe than sorry.” Source


Human Precautions for Harmful Algal Blooms (FAQs)

People should wear rubber gloves while bathing their dogs if they suspect contamination.

If you ingest water, fish or blue-green algal products containing elevated levels of toxins, you may experience headaches, fever, diarrhea, abdominal pain, nausea and vomiting.

If you swim in contaminated water, you may get itchy and irritated eyes and skin, as well as other hay fever-like allergic reactions. If you suspect you might have come into contact with cyanobacterial toxins and are experiencing any of these symptoms, rinse any scum off your body and consult your physician immediately. These FAQs are based on Senior Educator at MSU Stephen Stewart

  • Can I drink the water?
    • No – don’t drink untreated surface water. Boiling the water will also not remove the toxins
  • Can I cook with the water?
    • No – do NOT cook in contaminated water.
  • Can I bathe or swim in the water?
    • No – avoid contact with contaminated water. The longer people remain in the water the more severe the symptoms.
  • Can I use the water for pets and livestock?
    • No – pets and livestock should not consume water unsuitable for human consumption.
  • Can I eat fish caught from waters where HABs occur?
    • No – don’t eat fish as they concentrate toxins. If you live in an area where HABs occur, do not eat shellfish as they can also concentrate toxins from contaminated water sources.


What symptoms might I experience if I’ve been in contact with the water?

  • Skin rash, flu-like symptoms, tingling or numbness of the lips and mouth within 1/2 to 3 hours after exposure. Sever exposures might encounter: motor weakness, in-coordination, respiratory or muscular paralysis.


What if I think I’ve been exposed to algal toxins?

  • Rinse yourself and/or your pet off after swimming in any ponds, lakes, or streams. Get medical treatment right away if you think you, your pet, or your livestock might have been poisoned by algal toxins. Remove all other people from exposure.


Toxic Algae may not seem like a risk but it can happen devastatingly quick. Check for signs, proceed with caution near polluted water, & make sure to inform your friends of this silent killer.



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