Ovine and Caprine Surgery
When you have completed this chapter, you will be able to
• Display understanding of the basic differences between standing surgical procedures and general anesthesia procedures
• Prepare a sheep or goat for surgery
• Assist and/or perform induction and maintenance of anesthesia
• Provide anesthetic monitoring
• Manage the patient during recovery and immediate postoperative periods
• Display understanding of the basic risks and possible complications associated with anesthesia and surgery, and implement preventive measures when indicated
Small Ruminant Surgery and Anesthesia
Surgical procedures for small ruminants are similar to those for cattle. This chapter outlines the considerations and variations that should be made for small ruminant surgery. The reader should consult Chapter 12 for basic information on ruminant surgery.
Preparation for Standing Surgery
In small ruminants, food is withheld for 12 to 24 hours; it is not necessary to withhold water. Lambs and kids that are consuming solid food material should be fasted for 2 to 4 hours (withhold food only; water is permitted). In very young ruminants, the rumen/reticulum has little function, and the risk of regurgitation is minimal. Fasting of neonates may cause hypoglycemia and is not recommended.
Control of Pain
Sheep and goats especially are more sensitive to lidocaine. Sheep and goats may become toxic with lidocaine administration of 10 mg/kg total dose. For this reason, lidocaine should not be used in concentrations greater than 2%. Especially in goats, dilution to 1% or less solution is advisable; dilution of 2% solution with an equal part of sterile saline achieves a 1% solution. In kids, many clinicians advocate dilution to a maximum 0.5% solution.
inches long.Paravertebral Block
The paravertebral block is also used in small ruminants, but the needle should be an 18- to 20-ga × 
-inch to 3-inch spinal needle. A trocar is not needed for the procedure. In goats and sheep, the recommended volume of lidocaine is 2 to 5 ml per site. When the distal paravertebral approach is performed, a 20- to 22-ga × 1-inch needle is used in small ruminants, with 2 to 4 ml of lidocaine administered.
Cornual Nerve Block
Goats have a dual nerve supply to each horn; therefore, two sites must be blocked.
The cornual branch from the lacrimal nerve is blocked just behind the caudal ridge of the supraorbital process, at a depth of approximately 1 to 1.5 cm. A 22- to 23-ga × 1-inch needle is used, and local anesthetic (0.5–1 ml for kids, 2–4 ml for adults) is deposited.
The cornual branch of the infratrochlear nerve is blocked at the dorsomedial margin of the orbit, at a depth of approximately 0.5 cm. A 22- to 25-ga needle is used, and local anesthetic is deposited (0.5 ml for kids, 1–3 ml for adults) (Fig. 16-1).
Sheep are rarely dehorned. The nerve supply is only from the cornual branch of the lacrimal nerve; it is blocked using the same protocol as for blocking the cornual branch of the lacrimal nerve in goats.
-inch needle for caudal epidural administration. Because of sensitivity to local anesthetics, the dose should not exceed 0.5 to 1 ml of 2% solution per 50 kg body weight in sheep and goats.General Anesthesia
As with cattle, most small ruminant surgical procedures are performed with the animal standing. General anesthesia is required when the technical/anatomical aspects of the procedure or the ability to control pain and motion exceed the capability of sedative drugs and local anesthesia. The same precautions for cattle should be considered with small ruminants.
Inhalant Gases
In animals weighing less than 150 lb, facemask induction is possible. Adult sheep and goats may resist facemask induction unless they are sick or sedated. Oxygen (3–5 L/min) is given for 1 to 2 minutes before the anesthetic gas is introduced. Recommended gas concentrations are halothane 3% to 4%, isoflurane 3%, and sevoflurane 4% to 6%. Intubation is performed as soon as depth of anesthesia allows. A long-blade laryngoscope is useful for calves and small ruminants (Fig. 16-2). As with other species, appropriate size of endotracheal tube is estimated by palpation of tracheal diameter through the skin of the neck and usually is 10 to 12 mm in adults. Other commonly used drugs include diazepam and ketamine combinations and propofol in small ruminants.
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