Pet owners are reminded of a summer issue that can be as deadly as heat stroke. Small dog owners should be extra careful.

A vet said heat stroke is not the only thing to be careful of in summer. Water poisoning happens when dogs drink too much water.

It usually happens on hot days when dogs play in rivers and streams. They might drink a lot of water while playing.

This reduces salt in the blood, which can cause brain damage. If your dog is playing in water and drinking a lot, watch out.

Pet owners should be careful with all forms of water, not just rivers. It can happen at home with paddling pools and hoses.

Small and energetic breeds are at the highest risk. It takes less water to harm their smaller bodies.

The PDSA said owners may not know the risks until symptoms appear. Swallowing excess water can cause low sodium levels.

When this happens, cells try to rebalance by absorbing water. This causes cells to swell, and can lead to brain damage.

Dogs should be watched when playing in water.

You can prevent water intoxication by limiting water play. Don't use tennis balls in water, as they make dogs gulp water.

Pet owners should know the warning signs.

Severe signs include glazed eyes, pale gums, and difficulty breathing. Dogs might have seizures or lose consciousness.

Contact your vet if your dog shows signs of water poisoning. If treated quickly, most dogs recover, but it can be fatal if severe.