Veterinary Healthcare - Common surgical procedures in small ruminants (Proceedings)
Print
Common surgical procedures in small ruminants (Proceedings)


CVC IN SAN DIEGO PROCEEDINGS

C-Section

In sheep and goats, a c-section is a relatively easy and quick procedure. I prefer to have the females heavily sedated, positioned at 45° angle between sternal and lateral, leaning towards the right to expose the left flank. I like to position someone at the head of the animal, and tie the rear legs back (not stretch to tight, just to prevent her from moving legs forward and getting up). A ventral midline procedure can be performed, but in my opinion this stresses the goats more and may compromise breathing. If careful, all the lambs/kids can be removed through an incision in one horn.

Nerve Blocks In Goats

Nerve blocks procedures in goats are similar to other species. However, toxicity following administration of local anesthetics is more likely in goats. A maximum dose of 6 mg/kg of lidocaine and mepivicaine, and 2 mg/kg of bupivicaine is recommended. Diluting local anesthetics 50:50 with sterile saline to increase volume while not increasing total dose makes administration of small amounts to kids easier.

Cornual Nerve Block

This nerve block desensitizes horn and is appropriate for young animals with small horns. General anesthesia is preferred for older animals. Lidocaine hydrochloride is injected subcutaneously over the cornual branch of the intratrochlear nerve, which is located dorsomedial to the eye and adjacent to the margin of the orbit.

Caudal Epidural

A caudal epidural is indicated for some reproductive and obstetric procedures. 1-2 ml of 2% lidocaine hydrochloride is injected in the intervertebral space between the fifth sacral and first coccygeal vertebrae.

Lumbosacral Epidural

A lumbosacral epidural can be helpful in flank approaches to C-section. 2-3 ml of 2% lidocaine hydrochloride is injected in the epidural space at the lumbosacral intervertebral space.

Castration in Goats

Tetanus prophylaxis is indicated. For very young goats, castration is similar to calf castration. The distal one third of the scrotum is removed with a scalpel. Each testicle is stripped from the scrotal fascia and pulled ventrally to tear the spermatic cord. The incision is left open to drain and heal by second intention.

For older animals, either heavy sedation or general anesthesia in combinations with local anesthesia is indicated. The distal one third of the scrotum is removed with a scalpel. Each testicle is stripped from the scrotal fascia and cremaster muscle to expose the spermatic cord. A transfixation ligature is placed in the spermatic cord. An emasculator is placed on the spermatic cord distal to the ligature to provide hemostasis and remove the testicle. The incision is left open to drain and heal by second intention.

Dehorning Kids

Following sedation and cornual nerve block as describe above, an incision is made with a #15 scalpel blade around the base of the horn. The scalpel is then be used to cut under the horn bud to remove it. Pressure is applied for hemostasis. The site will heal by second intention. Alternatively, a portable dehorning iron can be used.

Dehorning Adult Goats

The advantages and disadvantages of dehorning adult goats must be weighed prior to performing this surgical procedure. Risks include development of tetanus, sinusitis, and myiasis. Other concerns include abortion, decreased milk production, death, prolonged healing time of the resultant surgical defect, and regrowth of the horns (scur formation). The surgical site may require 6-8 weeks to heal completely and should be bandaged or covered during this post-op period. Goats that have been dehorned should be isolated during the healing period to prevent trauma to the surgical site and owners should be advised that dehorning will likely alter the social status of the goat within a group.

Feed and water should be withheld for 24 hrs. and 12 hrs., respectively, prior to anesthesia and surgery. The patient can be sedated with xylazine 0.05 mg/# (20 mg/ml) and butorphanol 0.05 mg/# mixed together and given IM or IV. This combination provides good sedation and analgesia and can be followed with local analgesia by blocking the cornual and infratrochlear nerves, or, by the use of a ring block of 1% lidocaine placed at the farthest extent of the anticipated surgical incision. The infratrochlear nerve is blocked halfway between the medial horn base and the medial canthus of the eye and the cornual nerve is blocked halfway between the lateral horn base and the lateral canthus of the eye; both nerves are block by injecting (-1 cc of 1% lidocaine or bupivicaine SQ in these areas. To lessen the risk of lidocaine toxicity (muscular tremors, severe depression, hypotension and occasionally convulsions) avoid using more than 13cc of 2% lidocaine per 100# (<6mg/kg). If general anesthesia is preferred, ketamine and valium can be added to the above protocol by mixing ketamine and valium together 1:1 and administering 1cc/20# of the combination IV. In addition, inhalation anesthesia may be used. Xylazine can be effectively reversed if necessary using tolazoline at 4 mg/kg or 2 mg/# and butorphanol is often left >on board( for several hours of post-op pain control.

After anesthesia and surgical preparation, the skin is incised approximately 1.5 cm from the base of the horn being careful to incorporate all germinal or nonhaired epithelium in the horn removal to lessen the likelihood of regrowth or scur formation. With an assistant supporting the goat's head, a Gigli wire is seated under the caudal aspect of the skin incision on one side and the horn is sawed off in a cranial direction. Removing the horn in this direction prevents cutting too deeply at the caudal aspect which could result in penetration of the calvarium with exposure of the meninges and/or brain. Once the horn has been removed, hemostasis can be applied to control hemorrhage from the superficial temporal artery. In male goats in may be desirable to remove the scent glands at the caudomedial aspects of the base of the horns. Prior to bandaging the head, it is desirable to remove all blood clots and bone chips/dust from the frontal sinuses. The surgery site and open sinuses should be covered with a nonadherant dressing (AdapticŪ) covered with antibiotic ointment and then bandaged routinely. Care must be taken not to bandage the area too tightly. Bandages should be changed every other day for the first week then once weekly until the sinuses are closed. Flunixin should be administered for 2-3 days post-operatively and antibiotic administration is at the discretion of the surgeon. Tetanus antitoxin (500 IU) should always be given and a dose of a CD-T bacterin can also be administered to boost immunity.

Cosmetic Dehorning in Goats

There has become an increased demand recently for cosmetic dehorning in goats, especially for show purposes. In particular, we have been asked to cosmetically dehorn Pygmy goats as well as Boer goats. The best and most effective way to dehorn goats is when they are less than 2 weeks of age using a dehorning iron. If done properly, the chance of regrowth or scur formation is unlikely. However, some producers miss this window of opportunity; the kid may not be dehorned at an early age but later the owners decide that this may be a show quality goat. Consequently, we have been providing cosmetic dehorning for clients.

Two problems that exist when surgically dehorning goats are that there is often not enough skin to close the incisions once the horn is removed and the horns are so close together that the two incisions may actually join across the top of the head. To prepare for surgery we ask owners to hold the goat off feed for at least 24 hrs. but usually do not ask them to withhold water. The patient is sedated with xylazine 0.05 mg/# (20 mg/ml) and butorphanol 0.05 mg/# mixed together and given IM or IV. This combination provides good sedation and analgesia and can be followed with local analgesia by either blocking the cornual and infratrochlear nerve., or, by the use of a ring block of 1% lidocaine placed at the farthest extent of the anticipated surgical incision. The infratrochlear n. is blocked halfway between the medial horn base and the medial canthus of the eye and the cornual nerve is blocked halfway between the lateral horn base and the lateral canthus of the eye; both nerves are block by injecting (-1 cc of 1% lidocaine or bupivicaine SQ in these areas. To lessen the risk of lidocaine toxicity (muscular tremors, severe depression, hypotension and occasionally convulsions) avoid using more than 13cc of 2% lidocaine per 100# (<6mg/kg). If anesthesia is preferred, ketamine and valium can be added to the above protocol by mixing ketamine and valium together 1:1 and administering 1cc/20# IV or inhalation anesthesia may be used. Xylazine can be effectively reversed if necessary using tolazoline at 4 mg/kg or 2 mg/# and butorphanol is often left >on board( for several hours of post-op pain control.

To perform the surgery, a wide area around each horn is clipped and surgically prepared and an elliptical skin incision is made at the base each horn preserving as much skin as possible but making sure to remove all non-haired epithelium at the base of the horns to prevent regrowth. The skin is undermined away from the base of each horn and the horn is removed as close to its base as possible with the use of Gigli wire or a small saw. After horn removal, hemorrhage is controlled by twisting or ligating the cornual a. Additional bone must then be removed from the frontal bone with the use of bone Ronguers; this will allow easier closure of the dehorn site. All bone fragments and blood clots are removed and the surgery sites are flushed with sterile saline. The incisions are closed with non-absorbable suture such as #0 or #1 vetafil or nylon using a cruciate suture pattern. Since goats are notorious for scratching these incisions post-operatively, it is a good idea to apply a light, nonadherent bandage for the first few days. We also administer a single dose of antibiotics to lessen the risk of infection and banamine to provide analgesia and prevent excessive scratching. Always make sure the patient is current on tetanus vaccination, and, if in doubt, administer tetanus toxoid and antitoxin (two different sites) to be safe.