Pain management in food and fiber animals: What are our alternatives? (Proceedings)


Pain management in food and fiber animals: What are our alternatives? (Proceedings)

Aug 01, 2008

Table 1. Commonly used analgesic agents and suggested doses in horses. The dose and route of administration used for each patient must be determined on the basis of the clinical problems, systemic status of the horse, concurrent drug use and other relevant medical factors.
Pain management in food and fiber producing ruminants is often more problematic than in other domestic species. Analgesic protocols have not historically been incorporated into routine agricultural animal treatment plans because of the perception that they are too time-consuming, too costly, and too impractical for routine use. This is further exacerbated by subtle clinical signs of pain that are often poorly understood and under-recognized. Because there has been relatively little emphasis on pain management in food and fiber animals, it is not surprising that pharmacologic management of pain is sharply limited by availability of drugs licensed for use in food-producing animals, a lack of information regarding therapeutic analgesic strategies in these species, and related concerns regarding drug withdrawal times to avoid residues in meat or milk.

Table 2 Drugs for continuous rate infusion (CRI) for analgesia in horses.
Today the incorporation of analgesic treatments into agricultural animal medicine is slowly increasing world-wide in response to three very different influences. First, our abilities to recognize the behavioral signs of pain are improving for all animals species with resultant increasing awareness of the presence of pain in our patients. Second, an enhanced understanding of the adverse effects of uncontrolled pain on the well-being of animals and hence, on their long term production capacity, has increased the willingness of producers to spend the time and money required for analgesia in association with routine surgical procedures. Finally, there is growing world-wide demand for animal products produced in a "cruelty free" environment and increasing numbers of consumers are willing to pay higher prices for such products.

Behavioral Responses to Pain in Ruminants

Table 3 Drugs used for epidural analgesia in horses.
Behavioral signs of pain in ruminants are often quite subtle and may primarily manifest as an absence of normal behaviors. Cattle and sheep in pain may appear dull, depressed, and show little interest in their surroundings, separating themselves from the herd or flock. Unusual behaviors by an individual, not manifested by other animals in the group, may suggest the presence of pain. In cattle, these unusual behaviors may vary from total inactivity to restlessness to obvious hyperactivity. Any painful condition may impair rumen motility and cause a sudden decrease in milk yield. Cattle with abdominal pain may show abdominal splinting, grunting, tooth grinding, or arched back. More specific signs of abdominal pain such as kicking at the abdomen or rolling are less common in cattle than in horses. In sheep, grinding of teeth, head pressing, lip curling and cessation or rumination may occur with severe pain. After castration or tail docking indicators of pain in lambs may include repeatedly laying down and standing up, wagging their tails, or remaining immobile while standing. Goats tend to vocalize more in response to pain than do cattle or sheep. As with horses, ruminant species may show changes in their responses to human interaction as a result of pain. This may manifest as rigidity of posture, violent responses, or resentment of handling. Chronic pain may be manifested as changes in personality, loss of appetite, and decreased grooming behavior.