DEAR READERS: After I informed you about a class-action lawsuit concerning prescription-only pet foods, I received comments from two practicing veterinarians on these special diets, which are marketed in several countries.
From California veterinarian Dr. Greg Martinez:
"Many years ago, prescription diets were the only diets available that attempted to address common medical problems in pets. The 'sensitive stomach' and 'intestinal diets' had fewer allergenic ingredients than the common pet food on the shelves. These days, limited ingredient diets are healthy alternatives to help dogs with food allergies and intolerances to wheat gluten, beef and chicken. These commercially produced diets -- containing meats like fish, venison and rabbit, or carbohydrates like rice, peas or potato -- are commonly available at pet stores. Hydrolyzed prescription diets from soy have been helpful for those dogs and cats who don't tolerate animal proteins.
"The birth of prescription diets came after Mark Morris, DVM, adapted the human kidney-failure diets to his canine patients. The lower protein and phosphorus of kidney diets has extended the life of both dogs and cats with failing kidneys. Research shows that failing kidneys may benefit from these restrictions, but the very hint of kidney problems drive many vets to add kidney diets to the treatment plan before the lower protein diet is needed. An alternate sensible choice may be a moister food, like a senior diet canned food or home-cooked lower protein recipe with 30 percent meat and organs instead of 50 to 60 percent. Blue Buffalo's kidney support and senior diets are made with a better mix of ingredients than most other commercial brands.
"Omega-3 fatty acids are healthy antioxidants and may help with many organs. You don't always have to depend on the commercial or prescription diets when you can add fish oil or sardines in water to the diet!
"Urinary crystals and stones may result from a lack of moisture in the diet, food intolerances or allergens causing an irritated and infected bladder, and a genetic tendency to form stones. Struvite crystals and stones may benefit from canned or homemade food, cranberry extract, glucosamine-chondroitin supplements, antibiotics for infection and even probiotics. Oxalate and urate crystals and stones usually need a prescription diet like Royal Canin S/O or others to help prevent recurrence.
"For more details, visit my website, dogdishdiet.com and dogaware.com/health/kidneydiet, a great kidney disease diet resource."
Veterinarian Dr. Martin L. Whitehead from Oxford, England, where these same prescription diets are marketed as they are across much of the rest of Europe, sent me his opinion:
"My view on prescription diets is like that for nutraceuticals and supplements -- they each need to be assessed on their merits. I believe many prescription diets (cancer, congestive heart failure, cognitive decline) and many nutraceuticals and supplements are, at best, based on 'theoretical considerations' rather than actual evidence of efficacy. We sell very little in the way of prescription diets. I think the only use for them my practice has are:
"1. Restricted ingredient and/or hydrolyzed diets used short-term as exclusion diets to test for food allergies or intolerances in chronic GI and skin cases.
"2. Renal diets in advanced kidney failure cases. (I am not convinced they are optimal, but there is very good evidence that they are better than standard commercial foods in this circumstance.)
"3. Dissolving struvite stones.
"4. Something like Hill's a/D can be good for getting plenty of nutrients and energy into severely ill animals.
"Even so, the functions of each of these can be achieved using other foods and/or meds, but the manufactured diets are convenient ways of doing so for busy or uncommitted owners. The way I see it, all foods have their pros and cons. For feeding dogs and cats in general, in the absence of good evidence for what is best, my approach is to advocate variety. As an (economically unfortunate) result of that, as a practice we sell very little food because we don't promote any particular type.
"'Raw feeding' is growing in popularity in the U.K., and recently a Raw Feeding Veterinary Society (rfvs.info/) has been formed. I'm a member, although not a very popular one as I am fairly skeptical of much of what the other members claim. I don't have much objection to raw feeding (although I actively advise against it in families with pregnant women or young children), and I don't have much objection to pets eating manufactured foods, but I don't think either raw food or processed pet foods should be the only food animals get, and feeding an animal only one brand of manufactured food for months or years has always seemed outright peculiar to me."
Thanks to Robert F. Kennedy Jr., the global concerns over mercury pollution and poisoning are gaining greater public awareness. Sources include coal-burning power plants that lead to mercury contamination, especially of tuna and other seafood; amalgam dental fillings; and especially vaccines containing the mercury-based preservative thimerosal, which is 50 times as toxic to human tissue as the methylmercury in amalgams and fish. The link between mercury exposure and brain damage leading to infantile autism is documented in Kennedy's article posted on Ecowatch: ecowatch.com/mercury-linked-autism-kennedy-2116850430.html.
As I have pointed out for several years, companion animals can also be at risk to develop neurological and cognitive problems from mercury-contaminated pet foods and vaccines, which are given more often than to most children during these animals' lives.
(Send all mail to firstname.lastname@example.org or to Dr. Michael Fox in care of Andrews McMeel Syndication, 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.net.)