DEAR DR. FOX: I am writing in response to a letter in your column regarding the hypersensitive cat in Fort Worth, Texas.

My 3-year-old female longhaired cat is an indoor cat who longs to spend time outside, which we supervise. The only time she allows me to brush her is when she is sitting on my legs outside. As long as she is outdoors, I can brush her as long as I want. -- C.W., Olney, Md.

DEAR C.W.: Cats are curious creatures in that they react differently depending on where they are. This place-determining trait is indicative of their awareness and sensitivity to certain stimuli, to which we may be insensitive, but which provide some insight into our cats' behaviors.

Outdoors, your cat may be more relaxed and does not feel threatened by the intense stimulation of being groomed by you. This is an invasive experience for many cats who require time and patience to enjoy being groomed and managed. Indoors, your cat no doubt feels confined, and she may therefore resist holding and brushing. You should also consider static electricity being generated indoors while grooming your cat, which can be discomfiting. Grooming and brushing on a cotton sheet or towel rather than on a synthetic material that quickly generates static electricity may be worth a try. You could also use a moistened brush.

DEAR DR. FOX: You may have already addressed this in your column, but I believe it bears repeating: Xylitol, a sugar alcohol, is DEADLY to dogs. I know this from firsthand experience. Luckily, our dog pulled through, but it was because of fast action.

Late on a Friday night last August, as we were getting ready for bed, one of our Shelties, Buddy, got into a pack of sugar-free Tic Tacs. Within 10 minutes, he vomited, couldn't stand up and was shaking. I called our Animal Emergency Clinic and rushed him there. They said his blood sugar was dangerously low, so they administered two IVs -- one of glucose and one of saline. They kept him for 48 hours. His liver enzymes were rechecked and had dropped from more than 900 to 204. We will be checking them regularly.

Please put a warning in your column from time to time. People react with "Really? Tic Tacs did that?" Xylitol is in most sugar-free chewing gums, too. -- J.M., Cedar Hill, Mo.

DEAR J.M.: Many readers will appreciate your letter of warning regarding the highly toxic effects of widely used artificial sweeteners when ingested by dogs.

Xylitol triggers acute lowering of blood sugar by stimulating the release of insulin from the pancreas. Doses in excess of 1 gram per four to five pounds of body weight cause liver damage.

Gastric lavage (stomach pumping) may be helpful if the dog has recently swallowed xylitol-containing confections or chewing gum. Xylitol in baked goods remains toxic to dogs because it is not deactivated by heat.

DEAR DR. FOX: I know how hard it is to try and diagnose an animal without physical examination, but I really need an opinion, however general.

I cannot afford to take my cat to the vet as I am 76 and on a fixed income. My problem is a cat that belonged to my granddaughter, whom I have kept for many years as she couldn't keep him. He is an indoor cat, always healthy and sleek with a good appetite.

I noticed during the winter that his water bowl would be almost empty, abnormally so. He wasn't overly fond of wet food, and he ate a lot of dry. Things have lately reversed. He is craving wet food and seems ravenous for any kind of food, including my dinner. He jumps up to where I am eating and tries to lick my plate, which has odd foods he never tried to eat before and that a cat wouldn't normally like -- salad oil, spaghetti, etc. He jumps on the covered garbage pail and knocks it over because he smells scraps. I now feed him wet food twice a day, and always keep a bowl of dry food available for him. As much as he eats, he is losing weight. Over the past three weeks, it is very noticeable how thin he is getting.

He doesn't seem to be in any pain. He sleeps a lot, purrs and is still active, jumping on the sofa. I am tempted to just let nature and age take its course, as long as he isn't vomiting or bleeding. He could he have diabetes. If he were an outside cat, I would think tapeworm, but I examine his stools, and they look normal.

If you could advise, I would so greatly appreciate it. -- L.W. Asbury Park, N.J.

DEAR L.W.: You and your cat have my sympathy. Such ravenous appetite and weight loss can be due to a number of disorders appearing in middle-aged and older cats.

A hyperactive thyroid gland often combined with diabetes and possibly kidney disease and one form of cancer or another are the kinds of diseases a veterinarian would first check your cat for, and the diagnostics and likely treatment will not be cheap.

If your community has an animal shelter or humane society, call and see what kind of financial support may be available. Some veterinarians offer discounts and set up installment payments for services. The alternative is to make life as comfortable as possible for your cat: Make big batches of my home-prepared cat food (on my website, DrFoxVet.com), and give several very small meals of moist food and all the dry food he wants. Also, give him pinches of organic cat nip, available in pet stores, which most cats enjoy immensely. In the evening, give him 1 milligram of melatonin, available over-the-counter in drug and health stores.

(Send all mail to animaldocfox@gmail.com or to Dr. Michael Fox in care of Universal Uclick, 1130 Walnut St., Kansas City, MO 64106. The volume of mail received prohibits personal replies, but questions and comments of general interest will be discussed in future columns.

Visit Dr. Fox's website at DrFoxVet.com.)

DEAR DR. FOX: Today's Palm Beach Post has an article about a study of the effects of mixing chlorine with pee in pools. As it turns out, many people do urinate in pools. Apparently, the combination of uric acid and chlorine causes a chemical reaction. The dangerous gas cyanogen chloride is the result, which can harm the central nervous system, heart and lungs.

I thought of cat and dog owners who clean up accidents and litter boxes with bleach. I use white vinegar to clean up after my cats and used club soda as the immediate cleaner after my dogs' accidents. Perhaps you could look into this and give a warning to all your readers and pet owners. -- B.C., Palm Beach, Fla.

DEAR B.C.: Thanks for waving the red flag to minimize a possible risk from improper use of chemicals in the home environment. I NEVER suggest using bleach to clean things around the house, and especially for disinfecting various dog and cat urine and fecal deposits in and around the home. This fairly new information about the interaction of urine with chlorine in swimming pools underscores the hazardous nature of chlorine bleach products, which are also implicated in ozone layer destruction and endocrine system disruption. Safer enzyme cleaners, white vinegar and baking soda should be used in the home. Many people have died from inhaling mixtures of cleaning and disinfecting agents such as bleach with ammonia.

DEAR DR.FOX: I have two 10-year-old Devon rex altered female cats. They were born on the same day, but they are not littermates. They are very different in looks, size and temperament, but they get along well. They have always been very affectionate with us and others. They are indoor-only cats, have no fleas and are fed both wet and dry food.

Several months ago, the usually outgoing tortie began to groom her lower back a lot and would warn you if you tried to touch it. The vet said that many cats do not like to have their lower backs and tail area touched, but she had never minded before. Last week, she actually bit my husband while in her frantic grooming.

I began a Google search and believe that she is demonstrating the symptoms of hyperesthesia. We moved several times last year and have settled in Florida. We have had a lot of renovations done in the house and think maybe all the changes, noise and extra people in the house may have overstressed this normally pleasant cat.

She now has a bald spot on her back, and we have an appointment to see the vet again next week. We don't know how to help her stop the grooming. What can we do for this much-loved member of our family? -- P.M., Sanibel, Fla.

DEAR P.M.: You must first rule out hyperthyroidism, which is common in older cats and can be precipitated by stress when the thyroid gland is already compromised. One of the symptoms can be hypersensitivity to touch and obsessive-compulsive grooming. Another possibility, especially where there is much humidity, is a malassezia fungal infection.

In the interim, see if the cat will eat or drink a tea made from catnip that can act like Valium and have a calming effect for a few hours. Try a half-teaspoon of good-quality catnip, available in health stores. Some folks make a tea of it for themselves before bedtime. Another treatment could be one milligram of melatonin in the cat's food daily.

A possible food allergy, which could have been brought on by a change in the ingredients in the cat's usual food, should also be considered. Regardless of the same brand name, changes in ingredients from batch to batch of manufactured pet foods can pose problems. For more details, check my website, DrFoxVet.com.

(Send all mail to animaldocfox@gmail.com or to Dr. Michael Fox in care of Universal Uclick, 1130 Walnut St., Kansas City, MO 64106. The volume of mail received prohibits personal replies, but questions and comments of general interest will be discussed in future columns.

Visit Dr. Fox's website at DrFoxVet.com.)

DEAR DR. FOX: This isn't really a question, but it does concern the animals. I appreciate your advocacy of spaying and neutering to control pet overpopulation, as well as what you say about the huge farm-animal population and the need to reduce our consumption of animal produce. But what about the ever-increasing human population? -- L.E., Alexandria, Va.

DEAR L.E.: The human species is the worst of all planetary infestations! Human population control, through famine, disease and war, are ancient, arguably biologically natural and ecologically remedial correctives. Costs notwithstanding, pharmaceutical, surgical and educational components of family planning face enormous obstacles, cultural and political. Having many children provides cheap labor and economic security in some cultures. Politics are rarely divorced from corruption and the kind of disinformation that equates family planning with genocide.

There is a delicate balance between stabilizing populations through the economic security of technological industrialization and sacrificing cultural and biological diversity. If the wisdom of America's 19th-century natural philosopher Henry David Thoreau -- "That in wildness is the preservation of the world" -- is incorporated by all who are dedicated to improving the human condition, the relentless conversion of the natural world into a bio-industrialized wasteland may be averted.

Effective advocacy of population control through family planning is to be applauded. Opponents who make fatuous religious and moral claims such as the right to life of the unborn live in denial of the severity of the human infestation and its environmental, economic and health impacts on a planet of finite resources, and, in the process, bring more suffering into this world.

DEAR DR. FOX: Almost 10 years ago, a cat wandered into my parents' yard and had kittens two weeks later. I ended up taking in the mother, Kitty, and a daughter kitten, Dora. Until recently, I thought I had the best cats -- sweet with nice dispositions. I always felt so lucky.

A couple of months ago, Kitty started hissing at Dora. It went on for about three weeks, when I decided to take her to the vet to check on medical issues, since that's what most articles I read recommended. The vet did blood and urine tests and found that she had an ear infection, but the tests came back fine. I gave Kitty the prescribed eardrops. Within four days, things were back to normal, and they were once again snuggled up sleeping next to each other. On the fifth day, Kitty was sneezing a lot. I took her back to the vet. She had an infection. I opted for a shot because I was nervous about how well she would take medications from me. By that weekend, she was really sick. I took her back to the vet on Monday. She was given stronger medicine, and this made her better.

Then Dora came down with a respiratory infection. I took her to the vet, but this time I opted for oral antibiotics since they would be stronger. It was a nightmare trying to give her the meds. After two days, I tried a pate-style cat food, crushed the medicine and mixed it in. That seemed to work. But Kitty went back to hissing, and Dora started hissing and growling.

I took Kitty back to the vet again. The ear infection had not completely cleared, so she was put on eardrops for another 10 days. Sadly, the aggression escalated when I was at work. They must have had a fight -- there were tufts of fur around, and I found small tufts of fur under their claws. That night there was another incident.

Now I separate them when I'm not home and at night when I go to bed. Things are not getting better. I make sure they are not near each other to fight. Dora seems particularly traumatized by all of this. She is fine with me if Kitty is locked up, but she's skittish and a bit nervous. I hope you can assist in guiding me in the right direction. -- K.D., Brick, N.J.

DEAR K.D.: I am so sorry to hear about all the stress in your life dealing with sick and fighting cats. Your reaction to all the stress is probably also affecting your cats, creating a vicious cycle. Don't feel bad about that.

How and why the older cat developed an ear infection is a mystery -- thought it could possibly be an adverse food reaction. Any such discomfort can lead to defensive, aggressive behavior. You were wise to take the cat to the veterinarian. In the future, do try to get an in-home visit, especially for cats who may pick up respiratory infections even in well-run veterinary facilities.

One way to break the aggressive reactions of Kitty toward poor Dora is to try the plug-in pheromone called Feliway. Put this in the room with Kitty and in the room with you and Dora. Get a moist cloth and rub it on both cats repeatedly so they pick up each other's scent. Offer both cats good-quality dried catnip to eat -- I call it cat Valium -- then after they have eaten or smelled and rolled in it and you have rubbed some under their chins, let them be together briefly. Repeat this on a daily basis and be calm and quiet. Have a towel or pillow on hand to put between them to stop any attacks by Kitty.

If these steps do not help, she may need to have a thyroid function test done, since hyperactive thyroid disease can lead to temperament changes, increased irritability, self-grooming and ear and skin infections.

(Send all mail to animaldocfox@gmail.com or to Dr. Michael Fox in care of Universal Uclick, 1130 Walnut St., Kansas City, MO 64106. The volume of mail received prohibits personal replies, but questions and comments of general interest will be discussed in future columns.

Visit Dr. Fox's website at DrFoxVet.com.)