Dogs Trust is urging owners to take extra care once again amid another summer heatwave and to understand that a 'smiling' dog isn't always a happy one. The charity said an apparent grin with a wide open mouth and panting could in reality be a symptom of heatstroke and struggling to cool down, or even stress or trying to diffuse social conflict. The UK has been experiencing its fourth heatwave of the summer and daily highs are expected to remain above 20°C into the coming week. Heatstroke symptoms in dogs can include heavy panting, excessive drooling, appearing lethargic, drowsy or uncoordinated, vomiting, diarrhoea and collapsing. Flat-faced breeds such as English bulldogs, pugs and French bulldogs, are more at risk, as are older or overweight pet pooches. Heatstroke can be fatal. Where heatstroke is suspected, immediate action is needed. Owners should cool their pet first before travelling. They should stop them from playing, walking or exercising and move them to a shaded and cool area. Start cooling them down urgently, which for young, conscious, healthy dogs means immersing them in cold water such as a paddling pool, keeping their head above water. Use any water available, provided it is cooler than your dog. If immersion is not possible, continuous dousing with cold water is an alternative. For older dogs or dogs with health conditions, spray them with room temperature water, avoiding their face, and combine with air movement from a breeze, fan or air conditioning. Place ice, wrapped in a tea towel to prevent ice burns, in their groin and armpits. Always closely monitor cooling and stop if there are signs of shivering. Don’t place a wet towel over them as this can raise their temperature. Call a vet urgently for further advice and transport them there as quickly as is safely possible, with the air conditioning on in the car or the windows open. If the dog has collapsed or is struggling to breathe, call the nearest vet immediately.   To protect them from suffering heatstroke, dogs should also never be left alone in cars, even for a few minutes, and members of the public who see a dog in distress in a car are advised to call 999. Victoria Henry, Senior Veterinary Surgeon at Dogs Trust, says: "It’s easy to mistake a panting dog for a smiling one, but panting is one of the first signs of heatstroke, which can be fatal if not treated quickly. "Dogs can’t regulate their body heat in the same way as humans, so extra care needs to be taken. "As owners, we need to know the signs that our dogs are getting too hot and help them take a rest and cool down when they need to. "Some dogs aren’t good at self-regulating and may continue to run and play even though they’re hot and tired, which increases their risk of heatstroke. "If you do spot the signs of heatstroke in your dog, take steps to cool them down and contact your vet immediately.”