Vet Tom Carter is alerting pet owners to a potentially deadly summer hazard that is often overlooked: water poisoning. This condition, which can be as dangerous as heat stroke, occurs when dogs ingest excessive amounts of water, diluting their blood sodium levels and leading to hyponatremia.
How Water Poisoning Happens
According to Carter, a small animal vet based in Dorset, water poisoning typically occurs on hot days when dogs play in rivers or streams. "They might play with the ball, bite the waves and unintentionally consume a massive amount of water. This massively reduces the amount of salt in the blood, which pulls water across the blood-brain barrier into the brain," he explained. While the condition is rare, it can also happen at home with paddling pools or garden hoses.
Breeds at Highest Risk
Small-bodied and highly energetic breeds, such as Terriers and Retrievers, are most vulnerable because it takes less water to overwhelm their smaller systems. The People's Dispensary for Sick Animals (PDSA) warns that owners may not recognize the risks until symptoms appear. The charity stated: "Swallowing excess water can dilute a dog’s sodium levels, leading to hyponatremia. When this happens, cells in the body try to rebalance by absorbing more water, causing them to swell. If a dog’s brain cells swell, it can quickly lead to irreversible brain damage before the kidneys can sort out the sodium and water levels."
Prevention Tips
To prevent water intoxication, Carter advises limiting continuous water play to 15 minutes at a time and avoiding tennis balls in water, as they keep the dog's mouth open, forcing them to gulp water while swimming.
Warning Signs
Early or mild symptoms include loss of coordination, sudden extreme weakness, nausea and vomiting, excessive drooling, and bloating. Severe signs indicating brain swelling include glazed eyes, pale gums, tremors, difficulty breathing, seizures, or loss of consciousness. Pet owners should contact their vet immediately if any symptoms appear. Most dogs recover if treatment is started quickly and symptoms are not severe, but severe cases can be fatal.
