A swan that was attacked by a dog had to be put down after suffering severe injuries.

The Scottish SPCA said the bird would have "experienced immense pain and suffering" due to the severity of the wounds inflicted during the attack at Straiton Pond Nature Reserve in Midlothian on April 30.

A passer-by alerted the animal welfare charity after spotting that the swan was unable to walk on his right leg.

Scottish SPCA chief inspector Paul Anderson said: "The caller was worried the swan was out of the water and sitting in an area popular with people and dogs and was making no effort to protect his mate."

After securing a boat to help with the rescue, officers transported the animal to the Scottish SPCA's National Wildlife Rescue Centre in Clackmannanshire where vets concluded that the wing injury had been caused by a dog bite.

Chief inspector Anderson added: "Of greater concern to the vets was a badly arthritic leg that had become infected.

"This wound and condition was deemed untreatable and in the interests of the bird's welfare, the difficult decision was made to put him to sleep.

"This condition meant he wouldn't have been able to survive in the wild as he wouldn't have been able to get in and out of the water, fly and evade danger.

"It could have been the leg injury that made the swan an easy target for the dog in the first place.

"The swan would have experienced immense pain and suffering due to the severity of the dog attack wounds."

Following another recent dog attack on a swan at Victoria Park in Glasgow, the Scottish SPCA is urging owners to keep their pets under control.

Chief inspector Anderson stated: "This is a stark reminder to dog owners to keep their dogs on a lead around swans, and all wildlife, at all times."