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Keeping Fido Safe From Dangerous Blue-Green Algae

December 12 2025

A hidden threat lurks in many lakes and ponds, one that can prove deadly to your furry best friend. Cyanobacteria, also called blue-green algae, is a form of bacteria that flourishes in warm water. It emits a poisonous substance that is harmful—and potentially fatal—to both humans and animals. This is something all pet owners should be aware of, but it’s especially important for those who take their dogs swimming in fresh water. Continue reading to learn more about this hazardous poison from a local La Porte, TX  veterinarian.

What is Blue-Green Algae?

This kind of algae is especially harmful because it produces a unique type of poison. As the name suggests, it is blue-green in color, and often looks like paint or soup. It is most commonly seen in shallow lakes and ponds.

Blooms can occur if the average water temperature exceeds 75 degrees Fahrenheit, which is when many bodies of water are the most nutrient-dense. That means that the peak of the summer months, particularly during and immediately following the dog days of summer, are especially perilous. When the conditions are ideal, blooms can expand rapidly.

How is Blue-Green Algae Consumed?

Drinking contaminated water is probably the most common way dogs get sick, but it isn’t the only one. Toxins can also be ingested by humans and pets through the skin or by inhaling water droplets or mist. That implies you and Fido can get polluted while tubing, water skiing, swimming, floating, or boating. Even wading in contaminated water is dangerous. Pets can become ill after being immersed in water. They may later lick the cyanobacteria off their fur.

What Should I Do If My Pet Comes into Contact with Cyanobacteria?

The first step should be to thoroughly wash Fido. We strongly recommend calling your veterinarian as well. You may find yourself in a waiting game as you look for potential symptoms to emerge.

However, regardless of whether Fido swims in a pool, lake, or beach, we always recommend cleaning him off afterward, to remove sand, salt, and/or chemicals from his fur and skin.

How Long Does a Blue-Green Algae Bloom Last?

Individual blooms usually only survive for a week or two. However, when the conditions are right, they can be quickly replaced by another. For practical reasons, lakes might remain poisoned for weeks or months. This often occurs between mid-to-late summer and early autumn.

How Dangerous is Blue-Green Algae?

Blue-green algae is extremely toxic to humans and pets. Exposure may cause diarrhea, nausea, vomiting, skin rashes, eye and throat irritation, and respiratory discomfort. It may also result in major neurological issues and/or organ failure. Large concentrations of algae can be lethal if exposed or ingested. Unfortunately, no antidote exists.

Dogs and animals are particularly vulnerable because they don’t know any better than to drink the water.

How Do I Know If Blue-Green Algae Are Present?

Blue-green algal blooms are typically easy to identify and smell. Cyanobacteria is known as blue-green algae for a good reason. The blossoms frequently resemble pea soup or green paint. They also frequently produce a smelly, marshy stench.

However, you cannot judge lakes and ponds solely on their appearance. Smaller blooms may not be visible to the naked eye. Even if a lake or pond appears to be safe, conduct your own research and consult with local resources.

If you smell a swampy odor or see the telltale green scum, you should assume the lake is dangerous. However, as previously stated, you may not see the bloom. Stick to areas that have been cleared for swimming. Look for public signs: many local governments will publish notices once blooms are confirmed.

You can also refer to the HAB (Harmful Algae Blooms) map, which can be found here. This website gives updates on blue-green algae blooms in all states.

What Are the Warning Signs of Exposure in Dogs?

It is always vital to keep a close eye on your pet and look for indicators that something is wrong. Watch for symptoms such as panting, respiratory issues, vomiting, diarrhea, dizziness/disorientation, and excessive drooling. Seizures are another possible effect. If you observe any of these warning signs in your canine companion, contact your veterinarian or an urgent care pet facility immediately.

As previously stated, there is no antidote. However, appropriate supportive care can make a significant difference. Contact your veterinarian for further information.

Will Boiling Water Get Rid Of Blue-Green Algae?

No. This is crucial to understand if you enjoy camping with Fido and frequently boil water from lakes or ponds. Boiling may destroy live bacteria and microorganisms, but it does not eliminate cyanobacterial toxins.

How Else Can I Keep Fido Safe at the Lake?

Cyanobacteria is not the only potential threat to lakes. Swimming can be a lot of fun for Fido, but it can also be very dangerous. Some dogs simply aren’t made for it. If your dog is brachycephalic or has movement limitations, he will do better splashing around in a kiddie pool. Very small dogs are also at risk in the water because they can get above their heads in just a few inches. If you’re unsure whether swimming is appropriate for your dog, see your veterinarian.

If Fido gets the thumbs-up, follow these precautions:

Teach Your Pooch To Swim: If your dog doesn’t know how to swim, take the time to teach him. Never throw a puppy into the water and hope for the best. Encourage him as he learns by offering praise and comments.

Never Leave Your Dog Unattended: Always keep a watchful eye on Fido while he’s in the water. Never leave your dog unattended near the water. You should avoid taking him anywhere with blue-green algae blooms, as well as places with steep drops, large wakes, or strong currents. Red tides are also a risk for anybody going to the beach this summer.

Complete Your Pup’s Training: Your dog should also understand basic obedience instructions like Sit, Stay, and Come. This is critical because it prevents your dog from accessing a potentially unsafe place. If you’re taking your dog to the pool, take the time to show him where the stairs are.

Make Sure Fido Doesn’t Drink Bad Water: Finally, do not allow your dog to drink water from lakes, ponds, or puddles. We know, this may be easier said than done, but it is very important, and not just because of algal blooms. In addition to the risk of cyanobacteria, Fido may develop parasites like Giardia. In some places, he could also be exposed to snakes or other dangers.

Conclusion: Blue-green algae, often known as cyanobacteria, are harmful algae that bloom in many lakes and ponds during the summer. It is particularly harmful to pets and animals. In fact, exposure can be lethal to our canine companions. Pet owners must be aware of the dangers and understand how to spot and avoid blooms.

Schedule An Appointment With Our Pasadena, TX Veterinarians

Blue-green algae can be deadly to dogs. Our Pasadena veterinarians can teach you how to identify dangerous areas and keep your dog safe during outdoor activities. Contact us today for expert guidance on protecting your pup.

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