From personal experience, there are two inevitabilities of dog ownership. The first is that, at some point, you will step out for a walk and forget to take water for your dog. The second is that your dog is always happy to stick its nose into the smelliest thing around. So you have a thirsty dog, and there is a murky, stinky puddle over there? Bingo, problem solved. Or is it? What are the health risks to your pet from drinking from puddles? 

The bugs that lurk (in the puddle) 

Surely the worst that can happen from picking a bug up from a puddle is an upset tummy? Well, possibly. But given the most likely cause of this upset tummy is Giardia, and it is one of the most common causes of acute gastroenteritis in humans and animals. Apart from being very unpleasant for your pet (and for you cleaning up), Giardia can be quite difficult to treat. It is also not uncommon for a pet to have repeat bouts after they have recovered from the first one. Even worse, it is a zoonosis, which means it can potentially be transmitted from pets to their owners. Fortunately, it looks like this is rare in reality, which is a silver lining. 

Then there is leptospirosis, also known as “Weils’s disease”. 

That’s the one that your dog catches from rat urine, which can contaminate stagnant water. It is a serious bacterial infection that can cause liver and kidney failure. Dogs can contract it through contact with water contaminated by infected urine.  It can be pretty tricky to diagnose and very difficult to treat. Worse still, it is also a zoonosis. However, pet to owner transmission is probably very rare, with people most commonly contracting it through swimming or water sports in contaminated water bodies. It should be mentioned that leptospirosis in dogs is uncommon in the UK; this may be due to vaccination (none of the affected dogs in one study was vaccinated) or underdiagnosis. 

The new puddle-lurking nasty on the block is Angiostrongylus Vasorum, AKA Lungworm or French Heartworm. 

Infections in pet dogs by this unpleasant parasite have become increasingly common in the UK over the last two decades, particularly in the South East and Wales. Lungworm can cause lung disease, bleeding problems and neurological disease. It was previously thought to be transmitted by dogs eating slugs and snails. More recently, evidence has suggested that gastropods shed the parasite in the environment, and dogs can be infected by drinking contaminated water. 

And what about the toxins on your doorstep? A tale for all seasons. 

Even that harmless-looking puddles around your home could be life-threatening. Ethylene glycol is a commonly used ingredient in antifreeze products used in cars. It can easily leak from parked vehicles to contaminate puddle water. It’s highly toxic to dogs and cats, and only a small amount needs to be ingested to be fatal as it causes kidney failure. It has a sweet smell which means it is readily licked by dogs. Every year, sadly, several dogs (and even more cats) die in the UK after ingestion of ethylene glycol. As an antifreeze product, this risk is higher during the winter months. 

Then there is the danger of blue-green algae blooms caused by cyanobacteria. This natural phenomenon occurs most commonly during the summer months when the perfect conditions for explosive algal growth are most likely. The toxins produced by these blooms are dangerous to humans and dogs when ingested. Blue-green algae can often be visible by a blue-green foamy scum on the water’s surface. The local authority will put up prominent warning signs at times of high risk. It is imperative to keep your dog on the lead and out of the water when these signs are up. If your dog does somehow get into the water, it is recommended to take them directly to the vet for decontamination as toxic signs (tummy upset, tremors, wobbly gait, seizures) can start within an hour of exposure.

And then there is the bigger picture…

As with all issues environmental, the concern about environmental pollution is increasingly coming to the fore. Pesticides, herbicides to pharmaceutical residues and hormones, from agricultural, industrial and domestic use affect wildlife and the environment, and our understanding of how this happens is improving all the time. With that comes the realization that there is also a knock-on risk to our health and our pets. Yet still, the environmental levels of surprisingly few of these polluting substances are monitored. So exactly what, if anything, and how much of it ends up in your average puddle is unknown and, for this reason, drinking from puddles is generally not recommended. 

My dog has been drinking from puddles for years, and she’s okay. What is the risk, really? 

From reading this article, you would not be blamed for thinking that all puddles glowed fluorescent green and that it comes across as a bit alarmist. And you would be right. Most likely, a quick slurp from a puddle will do your pet no harm. Indeed, there is no need to contact your vet when your pet does so unless there are specific circumstances, like known blue-green algae risk or ethylene glycol exposure. What this article attempts to do is describe some of the potential harms of drinking from puddles. The trick is to take precautionary measures to minimize the risk, such as ensuring your pet is fully vaccinated and protected against lungworm if they insist on splashing through puddles. But the safest precaution of all is to always carry drinking water for your pet.

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