Introduction
The demand for veterinary anesthesia of free-ranging hoofstock has increased over time as hobbyists have increasingly collected them, exotic animal ranching operations have expanded, larger more progressive zoological collections exist, and state and federal natural resource management programs have demonstrated needs such as relocation.
The task of immobilizing a free ranging animal is inherently dangerous to the veterinary staff and possibly the patient. The environment must be considered in the protocol and procedurally the steps need to be well thought out. The skill of proper immobilization requires a background in biology and behavior, equipment used, and knowledge of the many effects of drugs on a wide range of species. …show more content…
These include but are not limited to hand delivery of anesthetic cocktails by needle and syringe, chutes, halters, and the safe use of rope restraint for quick procedures.
Pole syringes can be used for small volume injections if animals are just out of reach. Constant pressure must be applied quickly so as to deliver the medication before the patient retreats.
Certain highly concentrated drugs may be delivered remotely by blowpipe, compressed air projector, or gun powder cartridge rifle.2 If well chosen, these methods have distinct advantages in their nearly silent projection with minimal trauma upon impact. 1
Drugs
Early on, the standard of hoofstock immobilization was that achieved with succinyl choline chloride, a potent neuromuscular blocking agent that failed to induce unconsciousness or provide analgesia. Since then, ultra-potent opioids such as M99 etorphine, fentanyl, thiafentanil, and carfentanil have been used, often in synergistic combination with alpha-2-agonists like xylazine and medetomidine, the phenothiazine acepromazine, and the butyrophenones like azaperone and haloperidol. Hyaluronidase is often added to cocktails to enhance absorption, thus abbreviating …show more content…
Risks
As exotic hoofstock are difficult to predict the accurate weight of in the field, dosing inaccuracies (either too high causing cardiovascular and respiratory depression or too low causing undue stress during restraint) may be problematic. This can be offset by using combinations of higher therapeutic index drugs exhibiting a synergistic effect, thus reducing the anesthetists’ reliance on any one agent.
Furthermore, excitation may induce a physiologic response dampening the effect of a given drug. Should this occur in a fleet footed animal with a large range, they may run for some distance, escaping the anesthetist’s line of site, become recumbent, and succumb to cardiovascular depression, respiratory depression, drowning, or predation. 1
The patient may experience a sublethal to lethal exhertional myopathy during escape attempts or restraint prior to induction. This is characterized by a florid release of catecholamines, increased oxygen demand, hypoxia, anaerobic glycolysis, lactic acidosis, electrolyte derangements, hyperthermia, pulmonary edema, muscle necrosis, and possible