SEVEN million dogs are suffering from separation anxiety - and most owners don't even realise.

The RSPCA says our four-legged friends could be feeling frightened, lonely or sad when they are home alone.

The animal welfare charity said owners may not realise their dogs find it difficult to cope because the signs aren’t always obvious.

To highlight the “often hidden” issue, the RSPCA has launched a campaign called #DogKind to raise awareness and help owners understand their pet's emotional needs.

The RSPCA said that according to one study, around 50 per cent of dogs won’t show any signs that they are suffering with being alone and as many as 75 per cent of owners surveyed were unaware that their dogs were finding it hard to cope when on their own.

In an RSPCA survey, 22 per cent of owners had left their dogs for four or more hours and 53 per cent of dogs were left shut inside the house when their owners were out.

While 20 per cent of people reported signs of separation-related behaviour, but 45 per cent of people didn’t seek help and 20 per cent said it was because the behaviour didn't really bother them or their family.

DogKind campaign manager Daisy Hopson said: "We know that owners are the centre of their dog's life. So, when you leave your dog for any period of time, it can be incredibly difficult for them. It’s nothing to do with their age, breed or where they've come from. Many dogs don’t know how to cope when their owner isn’t at home and so are often unhappy when left alone."

The RSPCA's dog welfare expert, Dr Samantha Gaines, said: "Some dogs who find it difficult to cope when on their own bark/howl or destroy things to show their feelings, others will simply sit there suffering in silence. Like people, dogs express their emotions in different ways, so you may not always know if there is a problem.

Dr Gaines added: "There are lots of ways we can help our dogs if they’re struggling to be home alone. If they need something to occupy them then it can be a great opportunity to provide enrichment and stimulation such as toys stuffed with treats or puzzle games.

"If your dog struggles without company or you are out for longer periods of time then you could ask a neighbour, friend or relative to spend time with your dog or take them out for a walk. If relying on friends and family isn’t an option, there are services like DogBuddy which help you find a dog sitter near you for boarding, day care or walking. However, if you’re concerned that your pet is displaying signs of separation related behaviour then we would strongly recommend speaking to your vet or a clinical animal behaviourist for some specialist advice tailored to his or her needs."