Comments on changes in the veal industry

It is great to see that there is hope for progress toward animal welfare in the veal industry in this country.¹ In Europe, group housing for calves is standard—they are not confined in crates or tied to little huts unable to have any contact with the neighboring calves, as are most of the calves in the United States. It is a big step in the right direction for the board of the American Veal Association to acknowledge the fact that calves, like all young animals and children, have a natural need to play, romp around, and socialize with others. Hopefully, group housing will be in accordance with regulations that will give the calves enough room to do this. We as veterinarians should encourage and assist the American Veal Association in any way possible to reach their stated goal for the majority of calves as fast as possible, hopefully long before 2017.

Sylvia Heerens, DVM

Berkeley Heights, NJ

Questions updated euthanasia guidelines

I notice that the AVMA Guidelines on Euthanasia mentioned in a JAVMA News article¹ and published online and dated June 2007 does not include a list of authors, which is probably to the authors' professional advantage because their report inexplicably overlooks considerable work published between 2000 and 2007 regarding the use of carbon dioxide as a euthanasia agent.^2-6 These studies raise strong doubt that carbon dioxide is as humane as has been widely assumed and question its suitability as a routine euthanasia agent for laboratory rodents.

In my opinion, reissuing the AVMA Euthanasia report periodically without a thorough review of the scientific literature generated since its last publication is unacceptable, especially given that the guidelines are often cited within the scientific community as the final, authoritative word on animal euthanasia. Contrast this omission with the AVMA's meticulous attention to detail as it helpfully points out, in bold red letters no less, that the guidelines are not intended for use in human executions. The European Food Safety Authority's Animal Health and Welfare Panel report⁷ dealing with the topic of small animal euthanasia seems to be a far more up-to-date and comprehensive document.

Also, how is it that the AVMA Guidelines on Euthanasia, previously published as the 2000 Report of the AVMA Panel of Euthanasia, again issues a limp-wristed pass to the killing of small birds by compressing their bodies until they suffocate? This despite an absence of any scientific evidence that such practice is humane and considerable trans-species and common sense evidence that it is not. Certifying a method of “euthanasia” simply because it is widely practiced, in this case by field ornithologists on collecting expeditions, hardly seems a very scientific or ethical approach to me.

George Bates, DVM

Chambersburg, Pa

Dr. Golab responds:

We appreciate the opportunity to respond to Dr. Bates' letter. Unfortunately, it appears that Dr. Bates may have misunderstood information provided in the JAVMA News story regarding the June 2007 update to the AVMA Guidelines on Euthanasia.

In July 2006, the AVMA Executive Board approved a recommendation that the AVMA convene a panel of scientists at least once every 10 years to review all literature that scientifically evaluates methods and potential methods of euthanasia for the purpose of producing the AVMA Guidelines on Euthanasia. During interim years, requests for inclusion of new or altered euthanasia procedures or agents in the AVMA Guidelines on Euthanasia are directed to the AVMA Animal Welfare Committee for consideration; related recommendations are then sent by that group to the Executive Board for approval.

The first interim revision, approved in 2006, is the addition of a physical method (maceration) for euthanasia of chicks, poults, and pipped eggs. The document released in June 2007 reflects only that interim addition, rather than a comprehensive review or revision of the entire euthanasia document. In addition to information about maceration, a new paragraph was included in the preface of the June 2007 edition that explains the process for comprehensive updating of the report and differentiates this from interim revisions. As indicated in that explanatory paragraph, substantive interim revisions to the guidelines are highlighted by underlining the associated text. Because the authors of the 2000 Report cannot and should not be held responsible for interim revisions, their names were removed from the revised document; similarly, because the content of the report was changed, the name of the report was also changed.

We share Dr. Bates' concerns regarding the authoritative nature of the AVMA Guidelines on Euthanasia and the need for a regular, comprehensive, and meticulous review. With that in mind, the Animal Welfare Committee is currently considering various approaches for reconvening the panel and is expected to make its recommendations to the Executive Board in the near future.

Gail C. Golab, PhD, DVM

Interim Director Animal Welfare Division

AVMA Schaumburg, Ill

Additional information on melamine in pet food

The massive recall of pet foods that began in March 2007 has been attributed to adulteration of wheat gluten with melamine, a nitrogenrich (66.6%) compound associated with kidney failure. The role of melamine is still under debate. Based on studies in rats and mice and on one 1945 study¹ in dogs, melamine and its by-products are thought to be only slightly toxic. Tissue samples from kidneys and urinary tracts of affected cats contained crystals of melamine and cyanuric acid, but these contaminants were unexpected and not identified until six weeks after the recall.²

In the course of researching a book about pet food, we have come across studies suggesting that melamine adulteration has been a common practice and that melamine alone is toxic to sheep and cattle at doses similar to those that caused signs of renal disease in cats and dogs. In the early 1980s, Italian investigators surveyed the fraudulent use of melamine to boost the apparent protein content of animal feed. Adulteration was so common that the scientists developed a test for “melammina” and reported its presence in 56% of fish meal samples.³

The 1945 study investigated the legitimate use of melamine as a diuretic in dogs. At a dose of approximately 120 mg of melamine/ kg (55 mg/lb) of body weight, the dogs developed urinary crystals but no other adverse signs.¹ In the 1960s, South African investigators thought melamine might be a good source of nonprotein nitrogen for ruminants. But at doses of approximately 250 mg/kg (114 mg/lb), sheep refused food and lost weight; if fed low-quality hay, some died.⁴ Another investigator conducted a dose-response study. Doses of 25 to 100 g killed sheep, and necropsies revealed tubular damage and kidneys packed with melamine crystals so prominent that “Aggregates…were seen hanging from the prepuce.” When given lower doses, sheep refused food, especially when water was restricted. Results of the studies suggested that melamine doses of approximately 250 mg/kg could kill some, but not all, sheep in a few weeks.⁵ In the 1970s, doses as low as 100 mg/kg (46 mg/lb) induced four of six steers to refuse feed.⁶

The studies cited seem relevant to the recent recalls of melamine. The FDA's May 25, 2007, safety/risk assessment concluded that a 63 mg of melamine/kg (29 mg/lb) dose is safe. How much was in pet food? In the April 24, 2007, congressional hearing on the recall, the FDA estimated the amount of melamine in wheat gluten as 0.2% to 9%, and the amount of wheat gluten in pet food as 5% to 10%. Thus, the worst-case estimate is 900 mg of melamine in 100 g of food (dry weight). On a per kilogram of body weight basis, the amounts of melamine in adulterated pet foods could easily have exceeded doses known to kill sheep or harm cattle.

If those earlier studies were overlooked, it may be because most appeared in foreign journals not readily accessible through Internet searches. We found them the old-fashioned way, by going to the library and following the trail back to the original studies.

Marion Nestle, PhD, MPH

New York University

New York, NY Malden C. Nesheim, PhD, MS

Professor Emeritus Cornell University Ithaca, NY