Anesthesia Guidelines: Ruminants
General considerations
Acclimation
Do not use newly arrived animals for experimental procedures until 72 hours after entry into the facility. A one-week acclimation period is recommended.
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| anesthesia in a cow |
This stabilization period is not required for animals used acutely (anesthetized and euthanized at the end of the procedure), although it is recommended. This provision allows animals to acclimate to the facility and reduces the chance of stress-induced disease, including anesthetic death.
Padding and positioning
Proper padding and optimal positioning of ruminants during surgery is important. Whenever possible, standing surgeries with local anesthetic blocks are preferred. However, if recumbency is required, place ruminants on a flat surface with sufficient padding. A minimum of one- to two-inch thickness is recommended for calves, sheep, and goats. Because of their size, ruminants often require mechanical ventilation during anesthetic procedures.
Fasting
Fast animals for 24 hours prior to an anesthetic event.
Heat
Because most anesthetic drugs cause hypotension and hyperthermia, provide supplemental heat under anesthesia. Despite having wool, sheep become hypothermic during anaesthesia and standard methods should be used to maintain body temperature (insulating blankets, heating pads, etc.). Supplemental heat sources include circulating water blankets, air heating devices or commercial products that can be heated up or create heat via a safe chemical reactions. NO electric heating pads are allowed for use with ruminants. Regardless of heat source, never place animals directly on the heat.
Catheterization
Following sedation, place an indwelling catheter to administer anesthetic drugs, emergency drugs, and intravenous fluid support. The most common site for catheter placement is the jugular vein. Appropriate sizes for jugular catheterization: 16G or 18G in sheep, goats, or calves, and 12G or 14G in adult cattle.
Fluid support
It is important to provide supplemental fluid support. Appropriate fluid rates range from 5-10 mls/kg/hour, and may vary based on the anesthetic combination used.
Rumen tubes
Due to the propensity for ruminants to regurgitate and/or develop bloat, place a rumen tube in anesthetized ruminants.
Monitoring
Standard mammalian monitoring techniques apply to ruminants. The goal of monitoring should be to maintain cardiovascular homeostasis and core body temperature.
Understanding the basic physiologic effects of the anesthetics used is paramount to correctly interpreting monitoring parameters.
Parameters to be monitored in anesthetized ruminants include anesthetic depth, heart rate, respiratory rate, oxygen saturation, expired CO2 (EtCO2), temperature, blood pressure, and mucous membrane color.
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