DEAR DR. FOX: I recently read your article in which you said that after radiation for hyperthyroidism in cats, the cat would need continuing medication.

In 2010, my 14-year-old cat developed hyperthyroidism. Our vet said that she could either take medication for the rest of her life or go to Radiocat for a one-time treatment (at a cost of $1,300), after which she would never need treatment for that disease. We opted to do that at Radiocat in Baltimore. She spent four days there. She has been fine for five years, and has never taken medication for that problem again.

I feel that you misled the person who wrote to you. Her cat could have many more years of good health with no need for additional medication. I understand that Radiocat is available in many parts of the country. -- C.L., Frostburg, Maryland

DEAR C.L.: Thank you for comments and confirmation of the effectiveness of radioactive iodine (RI) treatment for thyroid cancer and hyperthyroidism in cats, giving me the opportunity to clarify my earlier response.

It is actually very rare for cats to need supplemental thyroid hormone medication after the mutated cells in the thyroid gland are selectively destroyed by RI. (That is not the case when put on anti-thyroid drug medication such as methimazole, which is also not without some potentially harmful side effects.) Periodic monitoring of blood thyroid hormone levels following RI treatment is advisable. This treatment is costly, and in all diagnosed cases of hyperthyroidism-associated heart disease, hypertension and age-related kidney disease must also be considered.

Signs of thyroid disease include increased appetite and thirst, weight loss, hyperactivity or apathy (depends on the case), irritability/aggression, excessive grooming, loss of fur on flanks, vomiting and/or diarrhea, panting, heat avoidance and seeking a cool place.

Mixed-breed cats seem more susceptible to the disease; there is a lower incidence in Burmese, Siamese and Persian purebred cats. The risk of this disease increases with age, thus reflecting possible accumulating environmental factors and chronic exposure to goitrogens (thyroid-inhibiting foods). Suspected factors that may disrupt thyroid activity and cause cellular damage and genetic mutation include soy products in many cat foods; erythrosine (red dye No. 3), especially in some canned pet foods; high iodine content; high concentrations of heavy metals and biphenyls in foods containing fish; bisphenol A (BPA) lining in canned foods; external anti-flea medications; and flame-retardant chemicals (polybrominated diphenyl ethers, or PBDEs) in carpets and other in-home materials. PBDEs are found in household dust. It gets into cats' fur, which they swallow in the process of grooming. Contaminants and additives in municipal tap water, fluoride in particular, given to cats to drink may also be contributory factors to this now-common endocrine disease in older cats.

DEAR DR. FOX: I was thinking about getting a collar for my newly adopted kitten, but then I remembered that my two previous cats lost their fur under the collar. The vet said the collars have chemicals in them. Is this true? If so, why do they sell them, and are there any safe collars I can get? -- D.L., Maryland Heights, Missouri

DEAR D.L.: Some cat collars come with an elastic insert so the cat can break free if he or she gets the collar snagged. Don't let your kitten roam off your property, and train him or her to enjoy going for a walk in a tight, escape-free harness with a leash attached to a regular collar around the neck. As I know from personal experience, some cats can wriggle out of their harnesses when they are scared.

The loss of fur on cats' necks could have been due to an allergic reaction to the material used to manufacture the collar, or more likely was an inflammatory response to anti-flea pesticides in impregnated collars, which are idiotic to purchase and totally unsafe -- imagine what the cat is inhaling and absorbing through the skin! I have been against flea collars for decades.

(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: We have a German shorthaired pointer-Lab mix puppy; she is not quite 5 months old. She has had two urinary tract infections. When she developed the second one, our vet did a urinalysis and said she had crystals in her urine. He prescribed Hills Prescription c/d dog food for her as a preventative for future problems, i.e. kidney stones.

Is this the treatment you would recommend? What causes this condition? Her infections both cleared up after a course of antibiotics. -- L.D., Alexandria, Virginia

DEAR L.D.: It is not unusual for young female dogs to develop lower urinary tract infections, and they usually develop some immunity as they mature. But once a bacterial infection becomes established, inflammatory reactions in the lining of the bladder and urethra cause pain and straining, often with the passing of blood.

Cellular debris becomes the nuclei for urinary crystal formation, most usually struvite crystals associated with abnormally alkaline urine, caused in large part by a high-cereal diet. So in an emergency, adding acidifying cooked organic tomato pulp was a popular remedy, but now d-mannose (found in cranberries) is another preventive suggestion. Try a dietary change, and encourage your dog to drink lots of water, even flavored with some home-prepared low-salt beef or chicken bullion.

Give your dog probiotics with low-grain or grain-free food, a selection of which is posted on my website (DrFoxVet.com). I would finish whatever antibiotic treatment cycle your dog is on and then stop. Phase out the costly manufactured prescription diet, and transition onto a raw or freeze-dried dog food if none on my website appeals to you.

DEAR DR. FOX: Our Dice (a 14-year-old male kitty) just left us, and we're heartbroken. He was diagnosed with kidney failure. I can't help thinking it may have been what we fed him for so many years.

In the last three years, we switched to Blue Buffalo wet and crunchy food, but he favored his Fancy Feast crunchies and Gravy Lovers wet food. Dice left behind our Bella, a 2-year-old female, who does not drink water but will eat Fancy Feast Gravy Lover's canned food.

Are we doing her more harm than good? Can you suggest any other food? There are so many on your website it makes me crazy! We do not want her to go through what our beloved Dice went through ... or any other kitty for that matter. -- T.G., Fort Myers, Florida

DEAR T.G.: There are many factors that contribute to renal failure in cats, and also in humans.

So many things can trigger autoimmune diseases, including kidney disease: the nutrition of the pregnant mother, what animals are fed, what contaminants in the environment animals are exposed to (especially in water and foods) and any infections and vaccinations they may have. We have disrupted and poisoned the planet and have a lot of housekeeping and cleanup to see to. Carnivores like cats living high up on the contaminated food chain are especially at risk. Organically certified whole food ingredients, raw food and freeze-dried are the wave of the future for cats.

I get crazier than you checking all the ingredients and sources of origin of various pet foods, and the best that I have found are posted on my website and by Susan Thixton on her website, truthaboutpetfood.com. Also check with feline-nutrition.org for more leads on feeding your future cats.

(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: I have a 14-year-old blue point Siamese cat named Simba. He will be 15 on Valentine's Day. On May 31, his half-sister passed away suddenly on my bedroom floor. Cali was 13 years old. Simba and Cali were inseparable, and when I tell you they did everything together, I mean it! After she died, I picked up Cali and put her into a basket and then put Simba into the basket to see she was gone. Simba just jumped out of the basket as if to say, "What are you doing to me?"

I took Cali to my local vet to be cremated privately. That night, when it was time for bed, it started. Simba walked the house screaming and yowling as if he was calling out to her. I was up all night. This went on for two weeks, and the nighttime screaming turned into daytime screaming. Then he started to rip out his hair. Over time, half of his body was bald. I took him to the vet, who put him on amitriptyline. It made him very loopy and unstable. Then Simba decided not to eat -- he was described as having failure to thrive.

After several trips to the vet, six months later Simba is thriving. This was the worst grieving experience I've ever lived through when it came to an animal. -- M.A., Nolan, New Jersey

DEAR M.A.: So many animals of various species develop close emotional bonds and suffer when their loved ones die. We humans need to be reminded of this and think of how surviving family members of wolves, whales, elephants and other highly sentient species must suffer when their mates and offspring are needlessly slaughtered. Thank you for this reminder from your cats.

DEAR DR. FOX: I was amazed that an influential veterinarian such as yourself would actually recommend that dog owners avoid neutering their pets.

The facts concerning animal overpopulation are well known. There are more than 70,000 puppies born each day in the United States, and if not neutered, each dog and its non-neutered offspring will result in more than 12,000 dogs born over the next five-year period. This results in the needless euthanization of over 3.7 million dogs each year. These dogs not only include mixed breeds but purebred dogs as well. It is also well established that neutering our pets keeps them healthier by reducing mammary gland, uterine, ovarian, prostate and testicular cancers, as well as perianal tumors and pyometria (uterine infection).

Neutering male dogs improves behavior by reducing aggression, dog bites and roaming, which often leads to death by car. Surveys indicate that approximately 85 percent of dogs hit by cars were not neutered. Most people will agree that our dear pets do not spend enough time with us on this earth, but by neutering them, their life span can be increased an average of 1 to 3 years.

Finally, please consider the financial implications in support of the capture, impoundment and euthanization of unwanted pets, which costs taxpayers billions of dollars each year. I find your trivialization of this problem through its characterization as an "inconvenience" offensive. -- F.B.K., St. Louis

DEAR F.B.K.: I appreciate your passion and documented concerns.

I have been a champion of animal birth control for more than 40 years and have set up programs in Africa and India to neuter pets. I try to spread awareness across the U.S. and Europe. I think spaying and neutering should be mandatory for all animals being adopted from shelters that are not no-kill because they have too many dogs and cats coming in.

One fact to get straight: I am not advocating a ban on spay/neuter, but rather applauding the fact that it is now being recognized that for some breeds, gonadectomy (removing the ovaries or testicles) may result in several endocrine diseases and contribute to other diseases, including some cancers, later in life.

So veterinarians are doing vasectomies and hysterectomies (leaving the testicles and ovaries intact) in some dogs so they cannot reproduce but retain the hormonal benefits of their endocrine sex organs. This is acceptable for those many dogs who are not allowed to roam free and have responsible caregivers.

I have limited optimism over the development of genetically engineered birth-control/neutering vaccines, not only because of past fights over patenting and intellectual property rights, but because of the possible triggering of autoimmune diseases.

From one animal rights perspective, neutering deprives animals of a normal, healthy and balanced endocrine system, which helps ensure their physical and psychological well-being. More prospective dog owners are beginning to request that their dogs not be totally neutered -- they should retain their endocrine sex glands. But where dogs are free-roaming and breeding at will -- as in countries like India, where I have worked with my wife, Deanna Krantz -- all sex organs should be removed, primarily to prevent temporary dog packs forming around dogs in heat, and then male dogs fighting. The net result in that situation, which also included vaccinations, was a healthier village dog community with no starving and unwanted puppies.

In a few years, when we have more clinical data, we may find that the mass neutering to help prevent pet overpopulation was a mixed blessing. It is a tragedy that dogs should suffer the consequences of human irresponsibility of being allowed to breed indiscriminately and are bred deliberately for the pet trade when there are thousands waiting to be adopted in shelters around the world.

(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.)