Abstract

All veterinarians engaged in the provision of veterinary care for small nondomestic mammals must possess a clinical knowledge of the behavioral manifestations of pain in each species. Equally important are a knowledge of the appropriate analgesic drugs for use in each species, and their response to each class of drugs so that an effective pain management plan can be developed for each patient.

The veterinary clinician engaged in a nondomestic species practice is further challenged by the lack of clinical studies regarding pain management in the species that he cares for. Practitioners providing care for such animals must rely on a diverse body of literature from both the human and veterinary fields to select the appropriate analgesic drug and management plan for the diverse species of animals that are under clinical care. The nondomestic practitioner must also be willing to be open to the inclusion of newer drug therapies in the development of pain management plans for his veterinary patients.

Assessment of Pain

The assessment of pain in animals is primarily on the basis of behavioral response to painful stimuli.¹ The evaluation of pain in a small mammal is made all the more difficult by the fact that behavioral changes in small mammals maybe more subdued than those of domestic species.

Acute responses to pain are generally similar in all species (i.e., escape or avoidance of the source of the pain). Individual animals may vocalize and become aggressive, especially if they are restrained. Following a persistent painful situation, such as accidental injury or surgery, most small mammal reduces their level of spontaneous activity and try to hide. They will usually remain immobile until handled, and then they may try to escape.

In addition to behavioral changes the animals’ external appearance may be altered. Small rodents may show a hunched posture, piloerection and soiling of the coat due to lack of grooming. Red colored porphyry secretions from the harderian gland may appear around the eyes and nose. If housed in groups, rabbits or rodents with pain may isolate themselves from their cage mates. Rabbits with acute pain may grind their teeth. As with other species, painful injuries to the limbs, spine, or abdominal musculature may result in abnormal positioning of the body parts or a “tucked up” abdomen.

A consistent sign of acute or chronic pain is reduced appetite (i.e., reduced food and water intake), and hence a loss in body weight. Daily body weight determinations one or more times daily will help the clinician assess the animals response to level of analgesia provided.

Analgesic Drug Selection

The selection of a particular analgesic for a pain management plan is based on its regulated status, ease of administration, required frequency of administration and species sensitivity to the available drugs. Although the elevation of pain is the goal of the clinician, each class of analgesics has the potential to exert adverse effects. The clinician must look for adverse responses and institute an alternative pain management plan in the event the analagesic must be withdrawn.

A listing of some commonly used analgesics by species and categories is listed below in the tabular form (Table 1).^2-5 Where specific information is lacking, the clinician can usually extrapolate the clinical response from similar species of animals to the current species under consideration for analgesic therapy.

Table 1. Analgesic drugs dosages for (mg/kg) small animals.^a

^aAdapted from the Heard.²

Summary

The relief of pain in animals must be approached on the basis of one animal at a time. Since the responses of any one animal can be highly variable, all pain management programs should be based on the individual’s response to therapy. Therefore, it is appropriate to reduce the dosage, increase the dosage, or shorten the period of treatment based on the response of the patient.

Literature Cited

1.  Dobromylskyl P, Flecknell PA, Lascelles BD, Livingston A, Taylor P, Waterman-Pearson A. Pain assessment. In: Flecknell P, Waterman-Pearson A, eds. Pain Management in Animals. Philadelphia, PA: W.B. Saunders Co.; 2000:53–79.

2.  Harcourt-Brown F. Textbook of Rabbit Medicine. Kent, UK: Elsevier Science Limited; 2002:94–120.

3.  Heard DJ. Anesthesia, analgesia and sedation of small mammals. In: Quesenberry KE, Carpenter JW, eds. Ferrets, Rabbits and Rodents. Clinical Medicine and Surgery, 2nd ed. Philadelphia, PA: W.B. Saunders Co.; 2004:356–369.

4.  Lipman NS, Marini RP, Flecknell PA. Anesthesia and analgesia in rabbits. In: Kohn DF, Wixson SK, White WJ, Benson GJ, eds. Anesthesia and Analgesia in Laboratory Animals. New York, NY: Academic Press; 1997:205–232.

5.  Wixson SK, Smiler KL. Anesthesia and analgesia in rodents. In: Kohn DF, Wixson SK, White WlJ, Benson GJ, eds. Anesthesia and Analgesia in Laboratory Animals. New York, NY: Academic Press; 1997:165–203.