I recently read a heartbreaking story about a dog at the lake that was playing with his family, chasing balls and sticks into the water and retrieving them over and over until he became extremely tired.

But he wasn't just worn out. He had ingested enough fresh water to cause his sodium levels to drop, known as hyponatremia. The main risk with acute hyponatremia like this is brain swelling. 

This is a deadly condition that we don't hear much about. It can be treated, but the prognosis is very guarded due to the effects it has on the body and brain in such a short period of time, and requires a rapid diagnosis and treatment. It is especially dangerous in smaller dogs.

The symptoms may include:

• Lethargy
• Bloating
• Vomiting
• Glazed over look in the eyes
• Incoordination or staggering
• Weakness 

How can you prevent this from happening? Make sure that the dog takes frequent breaks. The more they are working to retrieve, the more water they may want to drink from the lake. They also inadvertently swallow water while they are retrieving.

Dogs that like to bite at the water hose or sprinklers a lot could also be at risk. Knowing the symptoms and watching closely can save a life. If you know clients with dogs that may be at risk, it is worth mentioning to them so they are aware and can read up on this condition.

Here is a link to that story mentioned. Hanz was a very well loved dog and his owners are sharing his story to help educate other pet owners: Dog Dies After Playing Common Game With His Family.

After around an hour and a half, Hanz had been in and out of the lake more than twenty times to collect balls and sticks. He seemed content, but no one could have known the danger he was in.

Just a short while later, Jen realized something was wrong with her dog. The last time he returned from the lake, he didn’t shake off the water as he usually did.

Shortly afterwards, he slumped to the ground, looking “worn out”. - Read Full Article

For further reading on treatment, I recommend this article from VIN: Hyponatremia: Causes, Consequences, and Treatment by Dr. David Polzen