4 Ways Your Dog’s Water Can Make Them Sick

Among other waterborne illnesses, giardia and leptospirosis can wreak havoc on your dog’s immune system, so make sure you change out your dog’s drinking water regularly.

Never let your dog swim in water with obvious toxic algae bloom. By: pet1

Who’d have thought a small water feature could make a dog so ill? Indeed, not just any dog, but my precious Pogs.

For around 3 weeks, Pogs has been under the weather. Nothing terrible — just lacking her usual naughty mojo.

Oh, and diarrhea. Horrible, mustard-colored water leaking out of her rear end. Nothing wrong with her appetite. No vomiting. Just an unsettling runny stool, straining and mucus. Blech!

I followed my own advice to clients with ailing pooches. I starved Pogs for 24 hours and then reintroduced a bland diet, plus some canine probiotics. No change — I was still up every hour of the night to let her out to relieve herself. Time to up the ante.

A course of metronidazole and a vitamin B12 jab later, her bowel movements are back to normal. Phew.

But uh-oh: The next day, more diarrhea. Cue another course of antibiotics and ta-da — all is well.

But — and it’s a big BUT– the difference was we emptied out the water feature in our garden. Since she stopped drinking from it, Pogs has gotten better.

Pogs’ Tummy Upset

Pogs is a scavenger. She eats anything and everything on a walk. And if she can’t eat it, she’ll roll in it. Our first suspicion was she’d eaten a rancid mouse.

The first time around, given her nasty tummy, we kept Pogs on a leash and policed her “grazing” habits. We were certain she didn’t scoff anything she shouldn’t have. But, still, the diarrhea continued.

When she was first ill, given her habit of drinking from the water feature, we turned it off. When she got better, the husband turned it on again — and her symptoms returned.

Always provide fresh drinking water for your pet. By: Didgeman

Dangers in the Water

So what bugs could be lurking in less-than-fresh water? Quite a few, as it happens.

1. Giardia

This single-celled parasite may be better known to you as “traveler’s diarrhea.” (Yes, it can infect people too, not just pets.)

Giardia is shed in feces inside a hardy oocyst. The latter is tough and can survive for long periods of time in warm, humid conditions and thrives in water. When a dog drinks infected water, the parasite passes into their gut. Some dogs show no symptoms, but others can develop sickness and weight loss in addition to diarrhea.

A diagnosis is made by examining a fecal sample under the microscope. Most cases respond well to a 3- to 10-day course of fenbendazole (Panacur) or metronidazole.

2. Cryptosporidium

Cryptosporidium is similar to giardia but a whole lot tougher. Indeed, cryptosporidium is so tough that it can survive chlorine treatment. Similar to giardia, oocysts are passed in feces that, if they get into water, are a source of infection for animals and birds.

Again, the treatment is fenbendazole or metronidazole to kill the parasite in the gut. Also, bathe and shampoo the dog on the last day of treatment to wash away any oocysts clinging to the coat. Not doing so risks reinfection should the dog lick their fur.

If your pet is ailing after a swim, don’t wait — see the vet immediately. By: Pixabay

3. Leptospirosis

Leptospirosis is a particularly nasty infection with the potential to kill. It’s also a devious infection because signs can range from mild stomach upsets that last for weeks to months to acute liver and kidney failure that are fatal in hours.

Other symptoms include:

  • Fever
  • Muscle weakness
  • Blood in the urine
  • Loss of appetite
  • Vomiting
  • Diarrhea
  • Collapse due to organ failure

Leptospirosis can be spread by rat urine and especially loves water sources such as standing water, puddles and bird baths. The unpredictable nature of leptospirosis means prevention is the best policy. Happily, there are vaccines available. If you live in a risk area for lepto, then your vet will advise giving the vaccine.

A word of caution, though: The vaccine must be given yearly, as immunity is often gone completely 12 months after the previous dose. Oh, and pets can pass lepto to people. If your dog shows similar symptoms to those above and you feel unwell, see your physician as a matter of urgency.

4. Blue-Green Algae

You may be aware that dogs shouldn’t swim in water with an obvious algal bloom, but do you know why?

Cyanobacteria, also known as blue-green algae, are a toxin-producing form of bacteria. This toxin can affect any mammal (including people), causing nerve and liver damage. Signs of toxicity include:

  • Weakness
  • Muscle tremors
  • Drooling
  • Vomiting
  • Diarrhea
  • Breathing difficulties
  • Collapse and death

There is no antidote to blue-green algae poising. Treatment includes rinsing out the stomach to remove contamination and supportive care with intravenous fluids.

So don’t let your dog swim in dirty water or drink from containers of “old” water — give them the fresh stuff.

This Corgi learns to love “flopping” into the lake to retrieve his ball:

Good News for Pogs

With our water feature turned off and empty, Pogs is back to full health. Her tummy is perfect (do other families score their dog’s poop out of 10? Pogs is currently 9.5/10), and she’s rediscovered her mojo.

This means Pogs is back to rooting through long grass, jaws snapping like a crocodile, on the off-chance of snagging something scrumptious to eat. Hey-ho. Guess it won’t be long before she eats something she shouldn’t and the next tummy upset. But at least I’ve learned my lesson (the hard way) about the importance of clean drinking water for dogs.


This pet health content was written by a veterinarian, Dr. Pippa Elliott, BVMS, MRCVS. It was last reviewed July 13, 2018.

Dr. Pippa Elliott, BVMS, MRCVS

View posts by Dr. Pippa Elliott, BVMS, MRCVS
Dr. Pippa Elliott, BVMS, MRCVS, is a veterinarian with nearly 30 years of experience in companion animal practice. Dr. Elliott earned her Bachelor of Veterinary Medicine and Surgery from the University of Glasgow. She was also designated a Member of the Royal College of Veterinary Surgeons. Married with 2 grown-up kids, Dr. Elliott has a naughty puggle called Poggle, 3 cats and a bearded dragon.

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