Veterinary medicine and global food security
I was pleased to see the recent JAVMA commentary on the important role the veterinary profession can play in ensuring global food security.1
One important issue that I believe warrants more emphasis is the connection between increased consumption of animal products and global environmental harm. The authors note that climate change and overexploitation of land and water resources worsen global food shortages. Animal agriculture disproportionately contributes to both. A report2 from the Food and Agricultural Association of the United Nations notes that the livestock sector is responsible for roughly 18% of greenhouse gas emissions, a higher share than that attributed to transportation. Counting land used for grazing and feed-crop production, livestock production accounts for 70% of all agricultural land use and 30% of the land surface of the planet. In addition, it is the largest sectoral source of water pollution and biodiversity loss.
I contend that, as veterinarians, we should encourage a diversion of food choices toward nonanimal sources and away from animal products. Meeting nutritional (including protein) needs via plant-based sources is generally more efficient than meeting them through animal sources. A 2019 United Nations report on climate change calls for a global shift toward plant-based diets to improve global food security.3
Unfortunately, it appears that the veterinary profession sometimes advocates greater reliance on animal-source foods.4 Although the authors of the commentary seem to consider the increased demand for foods derived from animal sources as a background condition to which the veterinary profession must respond, I would argue that promoting food security and combatting climate change require decreasing this demand.
Also deserving of more emphasis is the veterinary profession's role in advancing animal welfare.5 The detrimental impacts on animal welfare of increasing animal production efficiency are well documented,6 particularly when it comes to the harmful effects of intensive confinement on physical, psychological, and social well-being. Society looks to veterinarians as experts in animal welfare, and our obligation to lead on this issue must remain central in any discussion of our role in ensuring global food security.
Gwendolen Reyes-Illg, DVM, MA
Humane Society Veterinary Medical Association
Milwaukie, Ore
1. Kelly AM, Galligan DT, Salman MD, et al. The epic challenge of global food security: a compelling mission for veterinary medicine. J Am Vet Med Assoc 2020;256:643–645.
2. Food and Agriculture Organization of the United Nations. Livestock's long shadow. Available at: www.fao.org/3/a0701e/a0701e00.htm. Accessed Apr 7, 2020.
3. Intergovernmental Panel on Climate Change. Climate change and land: an IPCC special report on climate change, desertification, land degradation, sustainable land management, food security, and greenhouse gas fluxes in terrestrial ecosystems—2019. Available at: www.ipcc.ch/site/assets/uploads/sites/4/2020/02/SRCCL-Complete-BOOK-LRES.pdf. Accessed Apr 7, 2020.
4. Nolen RS. AVMA weighs stepped-up role in global food security. J Am Vet Med Assoc 2017;250:822–826.
5. Kipperman BS. The role of the veterinary profession in promoting animal welfare. J Am Vet Med Assoc 2015;246:502–504.
6. Garnett T, Godfray C. Sustainable intensification in agriculture; navigating a course through competing food system priorities. Oxford, England: Food Climate Research Network and the Oxford Martin Programme on the Future of Food, University of Oxford, 2012.
More on declining wild bird populations
In their recent letter, Jessup and Hernandez1 claim that “the chain of causality between free-roaming cats and bird deaths is much clearer than that of plastics” and that “trap-neuter-release programs do not reduce free-roaming cat populations.” However, we believe that a closer examination of the evidence provided by the authors challenges these sweeping assertions.
The predation estimates cited, for example, are a result of computer modeling that relies heavily on rural studies dating back 70 years and more,2 rather than on more recent work3 showing that far more cats are found in areas of dense human population where anthropogenic food sources are abundant. As a result, the model's estimates are incompatible with the most recent North American Breeding Bird Survey data4 and, in fact, with the findings of the very study5 that prompted the JAVMA News article, “Bird population sees massive decline.”6
Jessup and Hernandez1 cite a review of wildlife rehabilitation center admission records indicating involvement of a cat7 but fail to acknowledge that such admissions made up just 8% of total admission records and that birds made up only 52% of admissions involving a cat. Similarly, Jessup and Hernandez1 note that “cats have been implicated in the extinction of 40 bird, 21 mammal, and 2 reptile species” but fail to acknowledge that these are extinctions from Australia, New Zealand, and small islands and that, in many cases, the precise cause of extinction remains a matter of speculation, with cats being just one contributing factor.8 We argue that such findings are not relevant to declining bird numbers in North America.
To support the claim that “trap-neuter-release programs do not reduce free-roaming cat populations,” Jessup and Hernandez1 refer to results of a population model,9 but they ignore the growing body of evidence suggesting that targeted sterilization efforts can, and often do, reduce free-roaming cat populations.10,11
Jessup and Hernandez1 also suggest that unowned, free-roaming cats are responsible for most bird deaths but offer solutions aimed only at pet cats (eg, confinement indoors and cat patios). Given the high rate of sterilization among pet cats, it seems likely that this population contributes relatively little to the overall population of free-roaming cats. In contrast, trap-neuter-return programs are aimed at unowned cats.
We believe that having the conservation community work with the animal welfare and veterinary communities to support and promote targeted trap-neuter-return programs would result in greater progress in reducing the number of free-roaming cats in our communities. Consider, for example, the DC Cat Count, an ambitious project aimed at better understanding free-roaming cat populations in the nation's capital, described as “a highly visible example of constructive collaboration between animal welfare organizations, wildlife scientists, academic institutions, and citizens.” Such efforts promise to go a long way toward protecting cats and wildlife alike.
Kelly A. Bettinger, MS
National Feline Research Council Advisory Board
Athens, Ga
Rachael Kreisler, VMD, MSCE
National Feline Research Council Advisory Board
Glendale, Ariz
Joan E. Schaffner, JD, MS
National Feline Research Council Advisory Board
Washington, DC
Robert Schmidt, PhD
National Feline Research Council Advisory Board
Logan, Utah
G. Robert Weedon, DVM, MPH
National Feline Research Council Advisory Board
Polk City, Fla
Peter J. Wolf, MS
National Feline Research Council Advisory Board
Phoenix, Ariz
1. Jessup DA, Hernandez SM. Decline in North American wild bird populations (lett). J Am Vet Med Assoc 2020;256:761–762.
2. Loss SR, Will T, Marra PP. The impact of free-ranging domestic cats on wildlife of the United States. Nat Commun 2013;4:1396. doi: 10.1038/ncomms2380.
3. Cove MV, Gardner B, Simons TR, et al. Free-ranging domestic cats (Felis catus) on public lands: estimating density, activity, and diet in the Florida Keys. Biol Invasions 2018;20:333–344.
4. Sauer JR, Pardieck KL, Ziolkowski DJ Jr, et al. The first 50 years of the North American Breeding Bird Survey. Condor 2017;119:576–593.
5. Rosenberg KV, Dokter AM, Blancher PJ, et al. Decline of the North American avifauna. Science 2019;366:120–124.
6. Mattson K. Bird population sees massive decline. J Am Vet Med Assoc 2019;255:1092–1093.
7. Loyd KAT, Hernandez SM, McRuer DL. The role of domestic cats in the admission of injured wildlife at rehabilitation and rescue centers. Wildl Soc Bull 2017;41:55–61.
8. Doherty TS, Glen AS, Nimmo DG, et al. Invasive predators and global biodiversity loss. Proc Natl Acad Sci U S A 2016;113:11261–11265.
9. Foley P, Foley JE, Levy JK, et al. Analysis of the impact of trap-neuter-return programs on populations of feral cats. J Am Vet Med Assoc 2005;227:1775–1781.
10. Kreisler RE, Cornell HN, Levy JK. Decrease in population and increase in welfare of community cats in a twenty-three-year trap-neuter-return program in Key Largo, FL: the ORCAT program. Front Vet Sci 2019;6. doi: 10.3389/fvets.2019.00007.
11. Spehar DD, Wolf PJ. Back to school: an updated evaluation of the effectiveness of a long-term trap-neuter-return program on a university's free-roaming cat population. Animals 2019;9. doi: 10.3390/ani9100768.
