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Water Toxicity and Hyponatremia

This time of year, we are generally more concerned that our pets aren’t drinking enough, but it is possible for them to drink too much. Like the old saying goes, it’s possible to have too much of a good thing, and water is no exception. Some dogs can ingest dangerous amounts of water in a short period of time, leading to hyponatremia.

Hyponatremia is the clinical term for low levels of sodium (called natrium in Latin, leading to the chemical symbol Na) in the blood. This generally occurs when there is a problem with the kidneys’ ability to excrete fluid, but is also caused by a dangerous excess of water, called water intoxication.

Water intoxication leading to hyponatremia is relatively rare but potentially fatal. It is most commonly seen in dogs that love to play in water; retrieving things thrown into the water and competing with other dogs retrieving things is one way a dog can ingest a lot of water quickly. It may also occur in dogs “catching” water from a garden hose or sprinkler.

Hyponatremia can lead to an increase of water in cells including those in the brain, so there are many neurological signs of this problem, including loss of coordination, lethargy, glazed eyes, excessive salivation, seizures and coma. You may also see bloating, vomiting and difficulty breathing. If your dog has been playing in water and shows signs of water intoxication, get them to the vet immediately as this condition is potentially fatal.

To use another old saying, prevention is better than cure, so it’s important to monitor dogs that are very active in water and ensure they get regular rest breaks. Also keep an eye on your dog when they’re in the garden if you have a sprinkler, and don’t let them ingest large quantities of water from a hose. When they empty their water bowl after hard play or exercise, give them a little break before refilling the bowl – this may seem counter-intuitive, but it’s important for them to pace themselves.  If your dog’s a guzzler, you can put a large, heavy stone in their water bowl to slow them down.

At the end of the day, it’s still very important for dogs to have access to fresh water, especially during heatwaves – we’re by no means advising restricting water supply.  However, it’s important to monitor how much your dog is drinking, as both too little and too much water can be potentially dangerous.