Scavenging canines have been left bleary-eyed after inadvertently feasting on cannabis while on walkies in northwest England.

Patch was one of several dogs "poisoned" after tucking in to a package left on a walking track in greater Manchester, British newspaper The Daily Telegraph reported.

"Patch was just totally out of it," said owner Neil Rogers of his four-legged friend.

"When I got home he just collapsed and couldn't do anything. I realised he had eaten something."

Mr Rogers returned to the track and collected the package, the contents of which police later identified as cannabis.

Veterinary surgeon Lorna Cook, who treated two of the intoxicated dogs, said: "I haven't seen anything like this before.

"We had two dogs with similar signs in quick succession so we knew there was something suspicious. Both dogs collapsed and had dilated pupils."

All the stoned pooches have reportedly made a full recovery.