Should You Let Your Dog Drink From Lakes or Rivers?

August 3, 2015

dog drinks michelleBy Linda Cole

Dogs are notorious for eating some disgusting things at times, which gives a false impression they must have a cast iron stomach. So it’s easy for dog owners to assume that a natural water source like a pond, river, stream or lake is safe for Fido to drink out of. However, there can be some nasty things lurking in the water that can harm your dog and put you at risk of developing a disease, as well. As responsible pet owners, we must beware of bacteria, parasites and chemicals that could be lurking in outdoor water sources.

There’s a reason we need to boil water taken from a natural water source before drinking it, and it’s the same reason pet owners shouldn’t allow their dog or cat to drink from ponds, streams, rivers or other water sources. Different bacteria species like E. coli and Leptospirosis, which are zoonotic diseases, can live in water and may pose a health risk to pets, along with other types of bacteria and infection-causing parasites like Giardia. Very young or very old dogs, and canines with depressed immune systems are at greater risk of developing medical concerns. Also keep in mind that boiling water won’t remove any chemicals present in it.


This bacterial infection can be transmitted from human to dog or cat, and vice versa. E-coli can be found in natural water sources used by wild animals. The water can become contaminated from human and animal feces. Most types of E-coli are harmless, but some strains can cause severe health issues. Symptoms can include dehydration, lack of appetite, lethargy, diarrhea and vomiting.


This single-celled parasite invades the intestinal tract causing weight loss, lethargy, vomiting and diarrhea, and can lead to dehydration. Other symptoms include upset stomach, body weakness and exhaustion. Humans with a compromised immune system have a small risk of picking up this parasite from their dog.


This bacteria species is found mainly in muddy, marshy, stagnant or slow moving water. These water sources may be used by infected wildlife like skunks, raccoons, opossums, rats and mice which are common carriers of the bacteria. The water and soil becomes contaminate from urine of an infected animal. It can be transmitted to humans through open wounds and in the urine of an infected dog. The bacteria finds a home in the liver or kidneys and can pose a life-threatening health risk to humans and canines. Symptoms in dogs include fever, loss of appetite, weight loss, lethargy, vomiting, diarrhea, joint/muscle pain, excessive thirst, excessive bleeding and jaundice. Vaccines are available for some of the more common strains that can infect dogs. Talk to your vet for advice about Leptospirosis vaccines if your dog’s lifestyle puts him at risk for exposure.

Blue-Green Algae

Colonies of red, green or brown algae can be found floating in fresh or saline (brackish) water, especially when the weather is hot. You might be able to detect a foul or musty smell coming from the water. Dogs that swim in water with these blooms can swallow some or ingest them when grooming. The blooms can be toxic to humans and dogs, causing life-threatening kidney, liver and intestinal issues. Blue-green algae can also affect the nervous system. Symptoms include skin rash, excessive thirst, nausea, diarrhea, vomiting, fainting, weakness, labored breathing, confusion, stumbling or staggered gait and seizures. Call your vet immediately if you suspect your dog has ingested blue-green algae.

Miscellaneous Water Sources

Ocean water contains salt that can cause an imbalance in electrolytes and lead to dehydration. Dogs that drink ocean water can develop diarrhea. Runoff from farm lands dog drinks andreicontains pesticides that end up in natural water sources, and waterways used by boaters can have gas and oil in them.

Some dogs enjoy swimming and playing in water, and some hunting breeds work in and around water. It’s not always possible to stop a thirty dog from grabbing a drink from a lake, river or stream, but he less he ingests, the better. Not all natural water resources are contaminated and may be safe to drink from; however, even a small risk is still a risk and it’s not worth taking a chance that a particular water source is safe.

Most organisms found in water can cause gastrointestinal and other issues, but they aren’t life-threatening. Nevertheless, if you don’t have a way to purify water from natural sources, it’s best to carry fresh drinking water for you and your dog. If your dog isn’t acting like himself and he’s been drinking from an outdoor water source, call your vet immediately.

Top photo by Michelle Tribe/Flickr
Bottom photo by Andrei Niemimäki/Flickr

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