Blood Mares and the Work of Naturalization

From the Series: The Naturalization of Work

Photo by College of DuPage Newsroom, licensed under CC BY SA.

In 2017, the animal welfare organization Tierschutzbund Zürich (TSB) released an update on their investigation into South American horse blood farms. At first glance, the report reads as yet another exposé of the long chains of violence underlying global animal agribusiness. But it also illuminates something else: how hidden ecologies are actively reshaped to generate new forms of labor. That is, blood mares offer a fleeting but suggestive glimpse at one small way that non-human actions and biology are being mobilized to naturalize human work—making a life of labor feel like a natural and inevitable part of being human (Weeks 2011).

While documenting the importation of horse meat into the European Union, TSB learned that pharmaceutical companies were engaged in a more lucrative trade with farms in Uruguay and Argentina. Or maybe farms is not the right word for these odd places, which operate in a regulatory gap outside rules that guide the generation of meat from domesticated animals. Thirty years ago, companies began renting privately owned forests. They populated them with thousands of semiwild mares that are left to fend for themselves—thus avoiding the cost of paying for feed or veterinary care. On these blood-and-timber operations, there appear to be only three main stages of human intervention: impregnation, weekly blood extractions over the initial few months of pregnancy, and abortion. Some 70 percent of bony mares survive being drained by brown hoses, and then are returned to the woods to begin the cycle anew. In the first half of 2017, one of these sites alone exported $10 million of blood in the form of 1.3 kilograms of Pregnant Mare Serum Gonadotropin (PMSG). PMSG, in turn, has become an important tool for the artificial insemination of pigs on North American factory farms.

The TSB report shook me, jolting memories of injecting this substance into hogs’ necks. But back then I only knew PMSG by one of its brand names, P.G. 600®.[i] It was just one of many small glass vials that line storage closets in barns. These hormones’ purpose is to temporarily manifest animal physiological states that are more conducive to laboring on porcine biology.

There are two primary reasons why PMSG is used in artificial insemination. First, it quickly brings sows back into estrus after their prior litter is weaned. It cuts down “unproductive days”—to use the pork industry’s own suggestive language—when sows are not working on gestation. Second, PMSG can help synchronize the expression of estrus across sows. It allows a crew of workers to enter a barn in the morning and be put to work inseminating rows of sows in cages. Mare serum assists the compression of sow reproduction into a nine-to-five industrial working-day window. It thus keeps human hands “productive” for more of paid labor time, as people rub sows’ backs in motions that imitate boars’ instinctual mounting behaviors. PMSG, in short, is a drug for labor: it is a capitalist substance that reduces total paid hours by engineering the expression of pig hormones and instincts, resulting in more constant forms of human work.

We might say that serum forests are vampire ecologies, and not just because of the blood-sucking. They reflect Karl Marx’s own description of capital as “vampire-like” dead labor—taking the form of things like machines—that hopes to feed on fresh labor. They further call to mind aspects of Sidney Mintz’s (1985) analysis of the mass production of the original industrial drug for labor, refined sugar. Cheap caloric energy derived from monoculture sugarcane on colonial slave plantations was marshaled to fuel nascent industrialism by speeding work and cheapening wages paid for British factory laborers’ biophysical subsistence. One could read TSB’s report as an updated (minor) neocolonial chapter to this kind of cross-continental flow of non-human substance for labor exploitation, without slavery but still channeled strongly through racial hierarchies. South American horses are impregnated with little paid work—and their blood profitably processed in European labs to make indigenous Central American migrant workers more intensely and cheaply weave labor through hog biology—to ensure that corporate shareholders’ North American sows are kept in a constant state of pregnancy.

When Mintz called sugar an industrial drug, though, his analogy was not steroids that increase physical strength. It was opium. Sugar provided pleasurable release from the factory’s rigors. And its dissemination from a bourgeois luxury to a working-class staple generated fantasies in the British metropole that the fledgling system of industrial labor can create a more equitable world. The production of PMSG, centuries later, has none of these real or imagined transformative qualities: it seems better described as a hidden, small, and almost sad effort to cling to a world of industrial labor. It is a complicated coordination of scientific knowledge, geographic inequality, and interspecies harm—all to find a couple extra pennies of profit in a pork chop. But after reading about blood mares, I think drugs like PMSG still have their own subtle psychoactive qualities, at least for the injectors. Furiously pressing sows’ backs during insemination, it always felt like my labor was the crucial force in the barns, that my own effort and skill alone would determine rates of conception. PMSG naturalizes work not only because it suffuses labor into animal hormones, or makes gestating sows thinkable as a kind of worker. It also creates conditions where human actions feel like the autonomous prime mover of the world. As we hear frets or hope concerning the end of work—when there seem to be fewer jobs to go around—we might pay more critical attention to how parallel lives and ecologies are being reconstructed to try to make human labor remain natural and necessary.


[i] Merck stopped acquiring blood from South America after TSB’s report. They continue to source from Europe, and other pharmaceutical companies maintain ties to South American facilities.


Mintz, Sidney. 1985. Sweetness and Power: The Place of Sugar in Modern History. New York: Penguin.

Weeks, Kathi. 2011. The Problem with Work: Feminism, Marxism, Antiwork Politics, and Postwar Imaginaries. Durham, N.C.: Duke University Press.