health, balding patch

Question
Hi i have a question about my parents 3 1/2yr old cat Rosie, her tail has a semi bald patch at the base. The top layer of fur seems to have fallen out or stopped growing leaving a layer of coarse short fur. There's no flakey skin, no parasite big enough to see with our naked eye and it doesn't seem to be an accident ie:she didn't get her tail caught or the little girl down the road didn't try to shave her(that's another story and another cat). She's an outdoor cat who has access to acres of gardens, woods, parkland could she have picked something up?

Answer
Hi Josephine.  Yes, it's very possible that Rosie has picked up something being an outdoor cat.  One thing extremely common, especially in outdoor cats, is ringworm, a fungal infection.  It causes baldness and usually itense itching.  Usually there is flakiness or puffiness or redness at the site of infection, but not always.  I have seen many atypical cases in cats, ones that the vets felt were no way ringworm but that cultures proved were.  This infection is EXTREMELY CONTAGIOUS to humans.

Another possibility would be scabies, mites which cause mange.  Though they do not reproduce in humans, they are temporarily contagious and can survive in human tissue for a couple of weeks causing intense itching.  Different vets choose different treatments, but all are by prescription only if you're in the U.S.

And even one little flea bite is enough to cause a severe reaction in cats who are allergic to fleas.  This is a common allergy.  If one flea hopped on, took a bite and then left, she could be suffering from a reaction to the bite for weeks.

There's a condition called "stud tail," too.  This causes the fur at the base of the tail to fall out due to excess oil production.  It's seen most often in unneutered males but is frequently seen in females as well.  Typically, you will see some waxy build up in the area, but again, not always.

There's a somewhat rare condition called Rolling Skin Syndrome, which causes extreme pain at the base of the tail and along the tail.  Cats with this condition will chew at their tails or the base of their tail to the point that they pull out their fur.  In some cases, they will literally chew their skin off.  Its cause is unknown, but it may be related to a seizure disorder, and some cases respond to seizure medications.

Autoimmune disease is another possibility.  The immune system turns against the skin.  Usually there is visible irritation.

Then we have staph, a bacteria which is usually present on the skin.  But any time irritation occurs, staph can infect the skin and cause itching and hair loss.

I think it's probably a good sign that there's some fur - usually if there's an active problem, the spot is completely bald.  Was Rosie ever completely bald in that spot?  If so, it's normal to see the rigid guard hairs grow back, first, which leaves a stubbly feeling.  The undercoat (soft, shorter, downy hairs) grow back more slowly.  

But in any case, I would recommend a vet visit, especially since some skin problems are highly contagious to humans.