A Christchurch man is facing an animal cruelty charge after allegedly feeding his dog a "cocktail" of chicken and insecticide to put it down.

SPCA Canterbury manager Geoff Sutton said the 62-year-old man decided to put down the german shepherd, which he had owned for about six years, after it bit his grandson.

Sutton said it was alleged the man fed the fatal chicken and insecticide meal, which the dog did not finish, on June 24.

"We're not challenging him because he put the dog down; it's the manner in which he did it," Sutton said.

The Press understands there is a veterinary clinic near the man's Halswell property.

It was alleged the man left the property after feeding the 9-year-old dog, and no-one witnessed the animal's final moments, Sutton said.

The man, who is retired, faces a charge under the Animal Welfare Act with killing an animal in such a manner that caused unreasonable or unnecessary pain or distress.

The charge, which carries a maximum penalty of 12 months' prison or a fine not exceeding $50,000, or both, has been brought by the SPCA.

Sutton said the SPCA was alerted to the matter by Christchurch City Council Animal Control, which was investigating the dog bite on the child.

Two days after the dog's death, the body was exhumed by the SPCA under a search warrant and underwent a veterinary examination, he said.

The man will appear in the Christchurch District Court on November 8.

- © Fairfax NZ News