An animal service has offered a $1000 reward for information leading to the identification of a person who shot a dog multiple times in the head and body, and left it to suffer.

A young male black and white crossbred, likely aged between 12 and 18 months, was found alive near Chamberlains Ford in Leeston on Anzac Day.

X-rays revealed multiple gun wounds. Bullet fragments had shattered the dog's jaw.

A decision was made to euthanise the dog due to the severity of its injuries.

SPCA Canterbury chief executive officer Barry Helem urged anyone with information to get in contact.

"It's inexcusable to leave a dog suffering like that, and it's in clear breach of the Animal Welfare Act."

The dog was underweight when it was found, Helem said, but it was hard to tell what the dog's background was like without speaking to its owner.

"The dog could have been lying on the ground for a considerable period of time before it was found."

The dog was wearing a red collar, but it had no registration tag or microchip. Police had been notified.

In the past 12 months the Canterbury SPCA had dealt with an increase in animal welfare complaints involving dogs.

Helem said he was concerned about the trend, and was working hard to educate the community on responsible pet ownership.

"It's not a quick fix."

The dog attack was not thought to be related to the discovery of Christchurch man Marcus Tucker's body near Lake Ellesmere, about a seven minute drive away. An associate of Tucker said he did not own a dog of that crossbred.