Canine “Drowning” on Terra Firma

It is summer and what better time for your dog to dive into your swimming pool or at a sparkling lake, or playfully bite at the water jets from your lawn sprinklers or garden hose.  When it’s hot outside, there is nothing better than a face-full of cool, refreshing water.  But beware, if your dog takes in an excessive amount of water, it can lead to an uncommon but deadly condition known as water intoxication.  Water intoxication can affect any dog but small dogs, high-drive dogs, and dogs with little body fat are at a higher risk.
When your dog’s body takes in more water than it can handle, it suffers a condition call hyponatremia, when sodium levels outside the cells are depleted.  The body attempts to rebalance itself by increasing fluid intake inside the cells in response to the low blood sodium.  Some organs have room to accommodate their swelling cells but others, like the brain, cannot as it is encased in bone.  The signs of water intoxication include lethargy, bloating, vomiting, stumbling, falling, staggering, restlessness, increased salivation, pale gums, dilated pupils and glazed eyes, and as pressure increases in the brain and cells begin to die off, the dog may have difficulty breathing, develop seizures, and lose consciousness.
It is believed that water intoxication is much more common than thought and it is frequently misdiagnosed.  Many first guesses at veterinary emergency clinics include head trauma, hypothermia, and overexertion.  A number of veterinarians don’t know water intoxication exists as there is such a minimal amount of literature published on the condition.  One of the only scholarly works found was published in 1925.  Even some internal-medicine specialists seem confused at how a water-logged canine body turns on itself, thinking that if the kidneys are working, excess amounts of water shouldn’t be a problem.  One sure sign of water intoxication is lower-than-normal sodium levels but it’s not how low the sodium falls as much as how quickly it falls.  The intake of water has stopped and blood-sodium levels may start to normalize by the time the dog gets to the veterinarians office but the cellular damage has already been done.  If a dog is showing neurological signs from wobbling to seizures, and if the dog has been playing in water from the garden hose, pool, lake, etc. then water intoxication should be a consideration.
Any dog who ingests too much water too fast can suffer water intoxication but advances quickly in small dogs because their bodies are easily overwhelmed by the excess fluid but high-drive dogs like Border Collies, Jack Russell Terriers and Papillion’s seem to develop it more than other breeds.  Because they are super-focused and high-energy dogs, they may be at a greater risk due to their personalities.  High-drive dogs are bred for agility and are obsessive about what they do.  Having said that, you would think the water-centric sport of dock diving would pose a higher risk of water intoxication but students of the sport have learned what to look for and how to combat it which includes taking breaks from swimming and using a flat toy for retrievals to keep the dog’s mouth from gaping open.  Also, dock diving dogs catch their toys in mid-air and their mouths are closed around the toy by the time they hit the water.  As their time in the water is limited, they have more opportunity to rid their bodies of extra fluid between runs.  Water work or retrieving bred dogs such as Newfoundland’s, Chesapeake Bay Retrievers, and Labrador Retrievers, to name a few, do not usually come up in discussions of water intoxication as these dogs have been bred for generations to move through the water with their mouths tightly closed and to create as little surface disturbance on the water as possible.
Mild cases of water intoxication may take care of themselves without being noticed by the dog’s owner.  The dog may come out of the water staggering but then un-dilutes by urinating, thus removing the excess fluid from the body before it is overwhelmed.  Since water intoxication involves a lack of sodium, replenishing this mineral is crucial.  Treatment includes the administration of moderate levels of electrolytes, drugs to decrease intracranial pressure, and diuretics to help speed the removal of excess fluid, but really severe cases probably won’t survive because the brain stem dies and that controls respiration.  There is too much permanent damage. 
Preventing water intoxication does not mean your dog must swear off any contact with water, just take adequate precautions which include choosing flat rather than round objects to retrieve.  When your dog retrieves a round object, he has to keep his mouth open wider than a dog who closes his mouth around a flatter object.  Also, the dog must hold his head up high in order to see a flatter object floating in the water.  Know your dog and how he interacts with water.  Some dogs are careful swimmers, with their noses pointed to the sky and their mouths clamped shut.  Others are more enthusiastic and like to splash in the pool or bite at the stream of water coming from the garden hose or sprinkler.  It is these dogs that are likely at greater risk than more reserved dogs.  Do not let your dog dive for toys as this will avoid water intake.  Water shooting from a garden hose does so under such high pressure that, even though it is so much fun, your dog could ingest far more water than he should.  It is important to take regular time-outs on land to give your dog an interruption from ingesting water and an opportunity to rid his body of extra fluid by urinating.  Tired dogs swim low in the water allowing for inadvertent intake of more water than if he was rested.
The opposite of water intoxication is salt-water toxicity.  Symptoms of hypernatremia (salt poisoning) include vomiting and diarrhea.  As fluid is drawn out of the brain and severe dehydration begins, neurological symptoms such as lack of coordination and seizures ensue.  Careful administration of IV fluids help to restore electrolyte balance as with water intoxication.  Offer your dog fresh water and frequent, shady rest breaks as a precaution when at the beach or seaside.
The best way to deal with water intoxication is to not let it happen at all.  Pay attention because it is real and it is out there.