It is an allegation that's both stunning and ironic - cruelty to animals at the Toronto Humane Society (THS). Just the very suggestion of the possibility has led the Ontario SPCA to serve a search warrant on the organization's River St. headquarters.

It centres on the THS's non-euthanasia policy, which has won it fans from animal advocates around the country. Unlike other entities, the Society has pledged it won't kill unwanted dogs and cats and tries to get them adopted out instead.

But when published reports alleged that the facility leaves animals that are dying from diseases or injuries in cages to keep that strictly enforced policy intact, the OSPCA pledged to investigate, arriving on Tuesday with an order to search the shelter.

"We received enough credible sources that have come forward that we have to respond and we have to make further enquiries," said the OSPCA's Kristen Williams .

The allegations stem from apparent former employees who contend there are problems going on behind closed doors. Some cruelty investigators have had their badges pulled as the probe continues, leaving them unable to look into reported cases of animal abuse in the city.

The THS denies the allegations and insists while its policy sometimes leads to overcrowding at the shelter, all the animals in its care are properly looked after and cared for.

"It doesn't accurately represent the way the Toronto Humane Society cares for its animals, and all our animals receive excellent care from the moment they arrive at our shelter to when they leave, either through being adopted, or through euthanasia, or passing away at the shelter which sometimes does happen," said  Ian McConachie, Toronto Humane Society.

Ontario's SPCA Act allows the Society for Prevention of Cruelty to Animals to probe any alleged wrongdoings by agencies designated to look after animals in the province.