In some instances the owners just don’t care, but in others they may have just misjudged how quickly the interior of a car can become critically hot: on a moderately warm day, when the thermometer is only nudging 22°C, the interior of a car can reach 47°C within an hour.
So what can you do if you see a dog in distress, and just as importantly, what should you do?
Assess the situation
Is the dog showing signs of medical distress? The RSPCA has a very good guide that sums up the symptoms of a dangerously overheated dog as:
• Panting heavily
• Drooling excessively
• Lethargic, drowsy or uncoordinated
• Collapsed or vomiting.
If you think that the dog is suffering any of these symptoms, you should call the police via 999 immediately.
10 dog-friendly beaches
If the dog isn’t in immediate danger
If the dog isn’t displaying any signs of distress then you can still call the police, but it might be quicker and more reasonable to ask any nearby shops and restaurants to put out a call on their tannoy system asking for the owner to return to their car.
If the owner does return, it's better to report the matter to the police rather than to confront the owner at the scene. Or the RSPCA has a 24-hour cruelty hotline - call 0300 1234 999.
Does a dog need a ticket on the train?
If the dog is in medical distress
If the dog is in distress, then your instinct will be to break a window and give first aid to the heat-stricken dog.
However, you should stop and assess the situation first because you could be committing the offence of causing criminal damage if you do so.
If you think that the dog’s condition is deteriorating, you should call the police back on 999 and explain the situation. Help may be arriving imminently and you just don’t realise it. If they're on their way, you could lessen the dog's distress by putting towels over the windows to try to block out the sun and keep the heat inside the vehicle from increasing.
But if the police tell you that they won't be able to respond immediately, you should ask their advice as to whether you can break into the car. They cannot give permission but there will be a recording of the incident and the fact that you've phoned the police to ask for immediate help – help that they cannot give – will strengthen your case if you feel that you have no choice but to break a window to gain access.
The RSPCA's advice is that if you feel the dog will die unless you take immediate action, then before you break in, you should take as many photographs as you can with your phone. You could even video the scene and your actions if you can.
Also take the names and address of any bystanders that are prepared to act as witnesses. All of this is good evidence that you acted reasonably and so have a defence against any possible charges. (In fact, having this to hand would possibly prevent charges being laid in the first place.)
The glass used in car windows is toughened, so ask everyone else to stand back before using your car’s tyre wrench to break in. Once you have access, be cautious; the dog may be vicious or just scared and you're at risk of being bitten.
If it's safe to do so, administer first aid. This means:
• Moving the dog to the shade.
• Dousing him with cool (not cold) water, or placing water-soaked towels or clothing on him.
• You could fan him with a magazine or newspaper to get some air moving over his body.
• Let him drink small amounts of water if he wants to.
• When he has recovered and his symptoms have eased, take him to a vet immediately to be checked over.
4 tips for dealing with car sick dogs
Subscribe today for just £12 for 12 issues...