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Too much too fast: Water intoxication in dogs.

May 23, 2019

It looks like winter has finally left us, and with warmer weather come all the warm-weather activities we love. For many dogs, that includes swimming. Let’s review a rare but serious condition that is an example of how too much of a good thing can be dangerous.

A quick simplified physiology lesson helps us understand what is going on with water intoxication. We all need water to live, but we also need it to be in balance. Cells of the body contain fluid called intracellular (inside the cell) fluid and are surrounded extracellular (outside the cells) fluid.

Intracellular and extracellular fluids maintain a specific balance between water, electrolytes, and other substances. The kidneys help maintain that balance by preserving or excreting water as needed, but they can only work so fast. If large amounts of water are ingested too quickly, the kidneys can’t keep up and the excess water can dilute the extracellular fluid enough for normal electrolyte levels (particularly sodium) to become very low (called hyponatremia). The cells, where sodium levels are normal, try to correct this disparity between the sodium levels in the extra- and intracellular fluids by drawing water into themselves, making them swell. Most of the symptoms of water intoxication that we see are due to brain cells swelling triggered by hyponatremia.

The early symptoms of water intoxication include confusion, lethargy, disorientation, stumbling, incoordination, excessive drooling, nausea, vomiting, “glazed” look to the eyes, pale gums, and dilated pupils. Later symptoms include labored breathing, collapse, seizures, coma, and death. Water intoxication progresses very fast, so it is important to seek care immediately if you suspect it. Emergency treatment includes administering sodium and diuretics (“water pills”) to rebalance the intra- and extracellular sodium and water levels, as well as drugs to help reduce swelling in the brain. With aggressive care, dogs can recover but because it progresses so quickly there are no guarantees.

The good news is, dogs are extremely unlikely to drink enough water in their normal day to day life for this to happen. The biggest risk is playing in or around water for long periods of time without breaks. Many dogs ingest large amounts of water when swimming, especially if they fetch toys from the water. Dogs who chase or bite at waves and dogs who like to “bite” water from a hose or sprinkler are also at risk, as are dogs who gorge large amounts of water after exercise.

Prevention is the best “cure” for water intoxication. Take frequent breaks out of the water, limit time playing with a hose or sprinkler, and offer water in small frequent amounts after exercise until your dog is rehydrated. There is no formula for exactly how often or how long to take breaks, because much depends on an individual dog’s play style.

Enjoy the summer, but be safe! Take breaks and keep an eye on your best friend. As always, if you have questions please feel free to contact the clinic.

Karen Christopherson DVM CVA


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