While the dust has already settled somewhat on this matter, I would like to dig it up and comment on it. In early May last month, an Ontario SPCA shelter, north of Toronto, had to deal with an outbreak of dermatophytosis, or ringworm, affecting about 350 animals. The original decision to euthanize all animals in the shelter was amended to have many of these animals taken in by local clinics to have them treated (thankfully).
Ringworm is a fungal disease of dogs, cats, and many other mammals, which can be transmitted to humans coming in close contact with infected animals. There are no worms in ringworm, named for a classic round lesion in people with a raised perimeter, giving the appearance of a worm under the skin. No worms in ringworm. The disease is not fatal but can cause severe hair loss and skin disease that can often look horrific. But it's not fatal.
The outbreak was blamed on human error, which lead to the dismissal of a manager there.
Here's my take: ringworm can look like a great number of other skin disease: scabies, a severe bacterial or viral skin infection, allergic skin diseases, endocrine diseases (such as hypothyroid or steroid dermatopathy), paraneoplastic syndromes, etc, etc, etc. In addition, cats and dogs can be asymptomatic carriers of ringworm, posing a risk to other animals and humans handling them. It is my suspicion (though I don't know for certain) that asymptomatic cats and dogs entering the shelter are not tested for ringworm, whose diagnostic tests requiring typically 2-3 weeks. Remember, this is a shelter, filled with rescued animals, not a single animal living the "good life," in some downtown loft. The responsibility of the OSPCA workers is to take in animals and treat them, if possible. There is no guarantee that any animal entering the OSPCA will be successfully treated, especially if it has a disease (even a curable one) requiring a lengthy and impracticable treatment, for a shelter.
While the decision to euthanize many animals sparked outrage and condemnation, in no way should the OSPCA employees be vilified for, or charged with, cruelty to animals. Shelter medicine deals with a population, not the individual animal. As sad as it is to put a dog or cat down because of ringworm, the greater picture dictates that the culling of some animals will allow a more expeditious return to a normal shelter environment, allowing anew the entry and treatment of pets requiring the OSPCA's services.
Classic lesion in a person: not hard to recognize.
Ringworm in a cat: not so classic.
What I have a huge problem with: the nutjobs who staged protests against the OSPCA, dressing their dogs up in black, who brought their children to a mock funeral (abounding with small coffins!) for the animals euthanized. This isn't normal human behaviour.