Hello, my name is***** and I have over 20 years of experience as a veterinarian. I'm really sorry to hear about Stuart's scratching and excessive grooming, matting, and poor coat condition.
The most common reason for these symptoms is flea allergy dermatitis. Flea allergy dermatitis is horrible. In allergic cats it only takes one bite a month for them to itch like crazy. If you don't see any fleas you might not have a huge population. If you have other pets who aren't itchy they may not be allergic. I am glad to know that you have used flea control but you must use it every 3 weeks in an allergic cat with known flea exposure. Many over the counter products have a problem with fleas being resistant and some can be down right dangerous. I never recommend any products that Hartz or Sargent's make. I recommend Advantage II, or Frontline Plus or products with Selamectin like Revolution or Paradyne every 3 to 4 weeks for at least 4 months, then monthly. All pets in the house must be treated as if you don't the nonallergic ones serve as a flea reservoir for the allergic one and you'll never solve your problem.
Since you know that your kitty has fleas realize that only 5% of the flea population lives on your cat, the rest is in the environment.
You need to vacuum your home throughly to remove as many eggs and larvae as possible. Concentrate on cracks and crevices, along baseboards, under furniture and areas where they like to sleep and eggs and larvae are at their highest numbers. Vacuum daily and throw away the bag.
I also recommend treating the home environment with a product that has an adulticide (kills adult fleas) as well as an insect growth regulator to stop egg and larvae from developing. A great product is Siphotrol II Plus Premise spray. I like it because it has an insect growth regulator as well as an adulticide. You can spray it under furniture and into cracks crevices and along baseboards where fleas and their offspring hide. It should be used every 2 weeks and no vacuuming for 2 to 3 days after using it to allow it to settle in. Here is a link to show you the product: http://www.amazon.com/Siphotrol-Plus-Premise-Spray-16oz/dp/B000RGKX7M
The trouble with foggers is that they don't go under furniture or penetrate cracks and crevices so they just aren't effective where they need to be. And they end up in the air where they are nasal irritants for animals and people alike.
Your other option is to have a professional exterminator treat your home and outdoors since Kiki goes outside. Ask for a guarantee and make sure that the products they use don't contain organophosphates and do have an adulticide and an insect growth regulator.
The key with flea treatment is consistency, not stopping too quickly, and using effective products.
Inhaled allergies (to pollens, dust mites or mold spores) are another possible reason for very itchy skin.
To control allergic symptoms you can try:
1) Benadryl (diphenhydramine only, the combination products with decongestants and acetaminophen are toxic to cats) at 1mg to 2mg per pound every 8 hours. That's one 25mg tablet every 8 hours for a cat that is 15 to 25 pounds.
2) Chlorpheniramine at 4mg twice daily.
3) Zyrtec (Cetirizine hydrochloride) at a dose of 5 mg per cat given orally every 24 hours. Make sure it is NOT the formulation with a decongestant (such as Zyrtec-D) because cats cannot tolerate decongestants.
Combined with high doses of omega-3 fatty acids antihistamines work to relieve his itchiness. I like 3V caps or Derm Caps. I recommend a dose based upon the EPA portion (eicosapentanoic acid) of the supplement as if we do that the rest of the supplement will be properly balanced. Give him 20mg of EPA per pound of body weight per day. For example an 18 pound cat could take 360mg of EPA per day. Antihistamines and omega-3 fatty acids work synergistically. These should help reduce the itch. Be aware that antihistamines can cause drowsiness or hyperactivity which should resolve with continued use.Food
allergy is another reason for excess grooming. You might wish to try a hypoallergenic food for 8 weeks or so. My suggestions are Hills Z/D or Royal Canin Duck and Green peas. He will need to eat only that food, no other treats or foods during his food trial.
If there are other cats in the home that he doesn't get along with or outdoors that upset him perhaps this is somewhat stress related. If so a product called Feliway, which is a synthetic version of a calming feline pheromone, may help. You can purchase this from petstores or online.
If he goes outside other parasites like Cheyletiella or sarcoptic mange are possible causes as well.
For now I would start with continued flea control, an antihistamine and omega 3 fatty acids. If he's not significantly better in 2 weeks then it's time for another veterinary examination to look further for problems and/or a hypoallergenic food trial.
Please let me know if you have further questions by replying to this post.