Humans have been using animals for their own purposes for as long as humans and animals have co-inhabited the planet. Our ancestors hunted animals as food, and over the millennia, humans have recognized animals as sources of clothing to protect them from the elements, fuel to light their lamps, bones from which to carve tools and jewelry, and even medically important compounds (eg, insulin) with which they can treat their diseases. Beginning more than 30,000 years ago, humankind recognized the usefulness of domestication and began to breed a variety of species to more readily serve its purposes. Humans saw the advantages of using domesticated animals as a source of food, a method of transport, a form of protection (from both people and other animals), and eventually a source of companionship.
Just as humans’ uses of animals have changed over the years, so too have society's views on animal welfare. The disparate roles that animals play in our lives have left a patchwork of animal welfare expectations across society. These society-wide differences in opinions regarding acceptable human-animal interactions and what constitutes acceptable animal welfare are reflected in the veterinary profession and can be described as a dissonance within the profession.1 This dissonance has been suggested to be a central challenge that could keep veterinarians from assuming a leadership role in animal welfare.2 In contrast, we believe that different perspectives within the veterinary profession merely reflect contemporary society and that it is incumbent on the profession to work with and through the norms and values of society in addressing the challenges of animal welfare.
The use of gestation stalls for pregnant sows represents an interesting example of these divergent perspectives within the veterinary profession, as veterinarians directly involved in the day-to-day care of commercial livestock often seem to have opinions regarding the welfare implications of gestation stalls different from the opinions held by veterinarians who do not have close connections to or experience with these animals.
In our experience, veterinarians involved in the day-to-day care of sows, particularly those familiar with group housing of sows prior to the advent of individual gestation stalls, tend to focus on the advantages to the physical health of the sows that gestation stalls provide, citing, for example, how individual housing prevents the aggression between sows that group housing allows and that can lead to the injury and removal of sows. From this point of view, gestation stalls can be seen as a tool that improves animal welfare by eliminating the adverse consequences of group housing and ensuring physical health.
In contrast, we often find that veterinarians who do not have experience in the day-to-day care of sows tend to focus on the fact that gestation stalls prevent animals from pursuing natural behaviors, such as turning around, and suggest that gestation stalls adversely affect sow psychological health as a result of the constant confinement they entail. From this point of view, gestation stalls can be seen as a barrier to good welfare overall because of their negative impacts on psychological welfare.
These disparate views about gestation stalls remind us of the parable of the six blind men examining an elephant.3 In the story, each reaches a different conclusion about the nature of elephants on the basis of observation of a single anatomic part (the man who feels a tusk, for instance, proclaims that an elephant is like a spear, whereas the man who grasps the elephant's trunk is just as certain that an elephant is like a snake). Thus, different factions of the profession have focused on different aspects of gestation stalls without adequately addressing the total complexity of sow housing.
Consideration of the behavior of sows in gestations stalls further highlights the complexity of farm animal welfare. As an example, bar-biting is commonly observed in sows housed in gestation stalls and is often interpreted as a stereotypical behavior that develops in response to the stress of confinement and is indicative of poor psychological health.4,5 More nuanced interpretations suggest that some stereotypies might actually be classified as coping behaviors, abnormal behaviors that animals develop to help cope with stressful situations.6 But, this raises the question of whether the affective state of sows that engage in bar-biting is worse than that of sows that do not. Of equal interest is the observation that misdirected chewing can also be seen among pregnant sows in housing systems that don't include individual gestation stalls.7,8 For example, sows housed in outside lots that have a variety of substrates available frequently chew on stones and drop them in their water bowls when they drink. In more barren environments, group-housed sows exhibit fictive or sham chewing—chewing on nothing but air. Clearly, this type of misdirected chewing cannot be attributed solely to the stress of confinement in gestation stalls. Stereotypies can reportedly arise as a behavioral response to hunger, a physiological problem, and we know that hunger is a concern in gestating sows, which are often fed limited amounts of concentrated feeds to maintain optimal body weight during pregnancy.9,10 It is possible, therefore, that bar-biting is not a response to gestation stall housing, but a manifestation of hunger. The challenge, therefore, may not be housing type but rather how to promote satiety without causing obesity.
Another example relates to whether sows housed in gestation stalls can engage in natural behaviors. Marian Dawkins11 recently offered a definition of animal welfare as the animals being healthy and having what they want. She goes on to argue that we should ask, when deciding whether animals require the opportunity to engage in natural behaviors, whether such behaviors improve their health and are things the animals want to do. If they do not meet both criteria, according to Dawkins, then there is no evidence that the behaviors are important to welfare, regardless of how natural they may be.
The challenge faced by the veterinary profession is to determine what matters to the animals themselves. Current science suggests that both gestation stalls and stall-free housing systems have their advantages and disadvantages and that no existing sow housing system meets all of the welfare needs of individual sows.12,13 Thus, we are left to ponder how best to balance the physical versus psychological health needs of sows, understanding that what defines an acceptable trade-off between the physical and psychological needs of a sow likely varies between individual animals. Social status means that dominant animals have minimal risk of poor physical welfare in group housing systems, whereas for subordinate animals, the additional protections associated with individual gestation stall housing may offset the decrease in freedom of movement.
Differences of opinion arising from differences in perspective are not limited to animal welfare issues and can be seen across many facets of the veterinary profession. These differences should not be considered a failing of the profession. Disagreement and discourse are imperative to progress. Veterinary leadership on animal welfare will not be achieved by striving for a common viewpoint or agreeing with social norms. Rather, veterinarians will continue to play a leadership role in animal welfare by acknowledging the complexities of scientific findings, clinical experiences, and ethical considerations. Only then can we construct a comprehensive and representative view that addresses both the physical and psychological health of the animals we serve.
1. Croney CC. Words matter: implications of semantics and imagery in framing animal-welfare issues. J Vet Med Educ 2010; 37: 101–106.
2. Kipperman BS. The role of the veterinary profession in promoting animal welfare. J Am Vet Med Assoc 2015; 246: 502–504.
4. Lawrence AB, Rushen J. Stereotypic animal behaviour: fundamentals and applications to welfare. Wallingford, England: CAB International, 1993.
5. Broom DM, Fraser AF. The welfare of pigs. In: Domestic animal behavior and welfare. 4th ed. Cambridge, Mass: CAB International, 2007;272–281.
7. Barnett JL, Winfield CG, Cronin GM, et al. The effect of individual and group housing on behavioural and physiological responses related to the welfare of pregnant pig. Appl Anim Behav Sci 1985; 14: 149–161.
8. Dailey JW, McGlone JJ. Oral/nasal/facial and other behaviors of sows kept individually outdoors on pasture, soil or indoors in gestation crates. Appl Anim Behav Sci 1997; 52: 25–43.
9. Bergeron R, Bolduc J, Ramonet Y, et al. Feeding motivation and stereotypies in pregnant sows fed increasing levels of fibre and/or food. Appl Anim Behav Sci 2000; 70: 27–40.
10. McGlone JJ, Fullwood SD. Behavior, reproduction, and immunity of crated pregnant gilts: effects of high dietary fiber and rearing environment. J Anim Sci 2001; 79: 1466–1474.
12. Rhodes RT, Appleby MC, Douglas KCL, et al. A comprehensive review of housing for pregnant sows. J Am Vet Med Assoc 2005; 227: 1580–1590.
13. AVMA. Welfare implications of gestation sow housing. Available at: https://www.avma.org/KB/Resources/LiteratureReviews/Pages/Welfare-Implications-of-Gestation-Sow-Housing.aspx. Accessed Apr 1, 2015.