Full-time indoor domestic cats should not get mange but they might. Mange is caused by an external parasite called a mite which lives on and in the skin of the host animal. There are a variety of species of mite. The word “mange” is an umbrella term to describe the itchy condition caused by these species of parasite.
One species called chiggers (Trombiculid mites) live as adults in decaying vegetation. So indoor cats are never going to be infested by this mite unless it is delivered to them from a cat, person or human that goes outside and walks within decaying vegetation. An indoor/outdoor cat might be prowling in forest grasslands and fields where chiggers reproduce, which occurs in late fall or summer. The pictures of chiggers on the internet show nasty infestations of people.
And the story of how chiggers can infest a full-time indoor cat is, in my view, the story as to how the other species of mite also end up on the skin or in the skin of full-time indoor cats. An animal or a person has to bring them into the home from the outside.
Mites that cause mange cannot fly or jump therefore they crawl from one animal to the other. Or an outdoor companion animal might deposit mites onto their bedding. A full-time indoor cat might use that bedding themselves. The mites crawl onto the full-time indoor cat and infests him.
Sometime humans can become infested such as with a mange which is called walking dandruff. The more scientific name is Cheyletiella mange. This is a large reddish mite that lives on the skin causing mild itching and was gives the impression of dandruff. It is highly contagious and humans can get it on their skin.
I would conclude, therefore, that a human could bring this species of mite into the home from the outside and give it to their full-time indoor cat. But the mite cannot live off the host for more than two weeks.
Head mange is also highly contagious. It is caused by the head might a.k.a. Notoedres cati. It causes intense itching. Cats self-mutilate through scratching to try and alleviate the itching. The mites tunnel into the skin and lay their eggs. It is transmitted mainly by animal-to-animal contact. Cats, dogs and people can be infested. Although dogs and people can be infested for short periods only, apparently. It only reproduces on cats and it cannot live for more than a few days off the host.
The question in the title is how do indoor domestic cats get mange? The answer must be that these ghastly little parasites are brought into the home on another animal or perhaps rarely a person. They’ve been picked up outside. It is strange, though, that nobody says that on the Internet and I’m referring to all kinds of veterinary websites. We need to know because cat owners need to know how to take proactive steps to stop it occurring in their cat.
My cat spends every night outside for many hours and he has never contracted an infestation of these skin parasites. So, I think they are fairly rare but it must depend upon where you live. The fact that they are incredibly irritating to a cat means that a cat owner must act quickly to get rid of them. And it should be a holistic attack by which I mean not only the cat is treated. A veterinarian will advise on the treatment having diagnosed the species of mite concerned.
But if you avoid a vet and do it yourself, be very careful as insecticides which kill external parasites are poisonous to cats and people in larger than prescribed dosages. Insecticides are about as nasty and the bloody mites that they kill.
Postscript: a lot of people won’t believe me but I have cured mange on foxes using a homeopathic treatment. Here it is:
I am not recommending it as I am unqualified. You put half a dozen drops on their food. I have never tried it on cats. They might reject the food.
SOME MORE ON MANGE: