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 firstname.lastname@example.org 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.)