Mad Pig Industry

The pork industry is bent out of shape about a two-sentence comment on the “possibility” that pigs may harbor a variant of mad cow disease, which appeared in my 16-page, single-spaced written testimony submitted to the House Agriculture Committee. 

In a section of my testimony where I urge the Congress to pass legislation to ban the mistreatment of downer livestock—animals too sick or injured to walk, who are dragged or pushed into the slaughterhouse—the following comment was included:

“Non-ambulatory cattle are not the only downer animals who may jeopardize the health of Americans. Scientific studies have pointed to the possibility that pigs, whose diet can include ground-up cattle remains, may harbor a porcine form of mad cow disease.”

© The HSUS

Mind you, this comment was buried in my testimony, and I did not mention it in my oral testimony.  Perhaps it would not have even gotten a second glance until the pork industry made it a public matter for debate by issuing a statement calling my comments not credible.

"Wayne Pacelle either misled Congress, or he’s ignorant of the facts," said Barb Determan, a pork producer from Early, Iowa, and past president of the National Pork Producers Council.

The NPCC statement reads: "The nation’s 67,000 pork producers would like to know if (Pacelle) intentionally misled (the) subcommittee, or did he fail to do research on the issue before testifying?"

Within the walls of The HSUS, I have a great expert to turn to on this matter—Dr. Michael Greger, The HSUS’ director of public health and animal agriculture. In 2006, he wrote "Bird Flu: A Virus of Our Own Hatching," which has been lauded by some of the most noted scientists who have studied avian influenza.

Dr. Greger focuses his work on the human health implications of intensive animal agriculture. I’ve asked him to offer his thoughts about the “possibility” that there may be a porcine form of mad cow disease. His perspective follows:

British government researchers proved that pigs are indeed susceptible to infection with bovine spongiform encephalopathy or "mad cow disease" in research published in 1990 in The Veterinary Record, the official scientific journal of the British Veterinary Association.¹ In a memorandum to the Veterinary Laboratories Agency of the United Kingdom, one of the researchers explained that the study provided “incontrovertible evidence of the transmissibility of BSE to the pig.”²

A number of studies have even suggested a link between pork consumption and Creutzfeldt-Jakob disease, an invariably fatal brain disease affecting humans. A study published in 1985 in the prestigious American Journal of Epidemiology,³ concluded that “consumption of pork as well as its processed products (e.g., ham, scrapple) may be considered as risk factors in the development of Creutzfeldt-Jakob disease.” The study was co-authored by Dr. D. Carleton Gajdusek, recipient of the Nobel Prize in Medicine for his research on these brain diseases.

Dr. Paul Brown, former medical director for the U.S. Public Health Service, also expressed concern in 1996 that pigs and poultry could be harboring mad cow disease and passing it on to humans. “It’s speculation, but I am perfectly serious,” Brown told New Scientist.⁴

The European Union has followed the recommendations of the World Health Organization⁵ and banned the feeding of slaughterhouse waste and blood to pigs as a preventive measure against mad cow disease, but this practice remains legal and continues in the United States.

The National Pork Producers Council claims that no naturally occurring cases of “mad pig” disease have ever been discovered. The Consumers Union (publisher of Consumer Reports), however, has petitioned the federal government to reopen an investigation into a case in which a U.S. Department of Agriculture veterinarian may have found a cluster of suspect pigs in New York (read the petition).

One reason we may not be detecting the disease in pigs is that it could take up to 16 months after exposure for the animal to develop the disease,² while pigs raised for food in the United States are typically slaughtered at less than 6 months of age.⁶ The British scientists whose 1990 study showed that pigs were susceptible to mad cow disease wrote in an internal memorandum that “it is plausible pigs could be preclinically infected with BSE, but since so few are allowed to reach adulthood this has not been recognized as a clinical disease.”⁷

A 2004 review in the Journal of Neuroscience (full text) goes further and suggests that there may in fact be cases of infected and infectious pigs who are “subclinical,” meaning they don’t display any symptoms and could therefore fly under industry radar.⁸

It is understandable that pork industry representatives would try to downplay the risk. By ignoring the science, though, they are doing a disservice to their producers and their customers. And ignoring something doesn’t make it so. I’d invite the naysayers to take a look at our supporting references:

1. Dawson M, Wells GA, Parker BN, Scott AC. Primary parenteral transmission of bovine spongiform encephalopathy to the pig. Veterinary Record. 1990; 127:338-9.
2. Memorandum from Wells GAH to Little TWA. In confidence: parental transmission of BSE to the pig. BSE90/8.29/3.1. August 29, 1990.
3. Davanipour Z, Alter M, Sobel E, Asher DM, Gajdusek DC. A case-control study of Creutzfeldt-Jakob disease: dietary risk factors. American Journal of Epidemiology. 1985; 122:443-51.
4. Pearce F. BSE may lurk in pigs and chickens. New Scientist. April 6, 1996: 5.
5. World Health Organization Consultation on Public Health Issues Related to Bovine Spongiform Encephalopathy and the Emergence of a New Variant of Creutzfeldt-Jakob Disease. Morbidity and Mortality Weekly Review. 1996; 45(14):295-6, 303.
6. U.S. Department of Agriculture. 2001. Part I: reference of swine health and management in the United States, 2000. National Animal Health Monitoring System. Fort Collins, CO. #N338.0801.
7. Memorandum from Dr. H. Pickles Med ISD/3 to Dr. Richardson PD and Mrs. Shorsby MCA. Experimental porcine spongiform encephalopathy. BSE23/1 0058. August 23, 1990.
8. Castilla J, Gutierrez-Adan A, Brun A, et al. Subclinical bovine spongiform encephalopathy infection in transgenic mice expressing porcine prion protein. Journal of Neuroscience. 2004; 24:5063-9.