Drug dealers are injecting dogs with heroin so they become more violent as the effects of the drug wear off, an animal charity has revealed.
The Angus Dog Shelter has warned dealers are injecting dogs with the class A drug so they turn aggressive when withdrawal symptoms set in.
The shelter also say dealers are training dogs to attack police when they raid homes by dressing up as officers and goading the animals to attack them.
Owner of the Angus Dog Shelter in Forfar, Scotland, Ian Robb say that last year, 40 percent of dogs admitted to the shelter were addicted to drugs.
Robb told the Daily Record: "In some cases it's cannabis but in most it's heroin, which has a devastating effect on an animal."
Robb, 64, said the worst example of was in Perth two years ago when tow Staffordshire bull terriers were put down because they were regularly injected with heroin.
He added: "The animals had been trained to attack a uniform and cause mayhem during any police raid on their owners' homes.
"They were absolutely bouncing off the walls when they were handed in to the local dog rescue centre and had to be destroyed.
"They were beyond help. It was absolutely tragic."
Robb added: "Dealers go out and buy a fake uniform and teach the dogs to attack someone wearing it.
"When the police turn up, the dog doesn't know any different and goes for them."
Dog psychologist Lesley Connelly, said: "Some owners give the dog drugs for a laugh to see what would happen - but others get them hooked because it makes them much more aggressive.
"A dog on heroin will run around, leap up the walls and will be completely manic. If you attempt to approach it you will get bitten.
"We normally leave them alone until they start coming down off the drug. It's a bit like 'cold turkey' in a human."
Scottish animal welfare charity SPCA has said they have not received any direct reports of dealers deliberately giving drugs to their dogs.
Chief superintendent Mike Flynn said: "Such an action would be an offence under the Animal Health and Welfare Act (Scotland) 2006.
"However, we are aware of instances where dogs have accidentally consumed illegal and prescription drugs, often with fatal consequences."