This document provides information on principles of anesthesia use in cattle. Some key points include: 1) Cattle are not ideal subjects for heavy sedation or general anesthesia due to risks of regurgitation and aspiration. 2) Common sedative drugs used in cattle include xylazine, detomidine, medetomidine, acepromazine, chloral hydrate, and pentobarbital. 3) Local anesthesia techniques described include nerve blocks and intravenous regional anesthesia.

1. Principles of Anesthesia Use in Cattle
15-ARID-4445
DVM 5TH
EVE
Anesthesiaof Cattle:
Cattle by no means good subjects for heavy sedation or general anesthesia. Regurgitation
followed by aspiration of ruminal content into the lungs can easily occur. Once a ruminant
animal is in lateral or dorsal recumbency, the esophageal opening submerged in ruminal
material, normal eructation cannot occur and gas accumulates. The degree of bloat depends
upon the amount of fermentation of the ingesta and on the length of time that gas is allowed to
accumulate. Gross distention of rumen becomes a hazard if anesthesia or recumbency is
prolonged and regurgitation can follow from this. The weight of abdominal viscera and their
content prevent the diaphragm to move freely on inspiration and ventilation becomes shallow,
rapid and inefficient for gas exchange within the lungs.
Regurgitation and inhalation of ingesta can be minimized by:
1. Withholding all food for 24 hours to 48 hours before anesthesia. Optimum duration for
starvation is up for discussion, with some recommendations that 24 hours is not only
sufficient but also produces the best consistency of rumen contents to minimize
regurgitation.
2. Withholding water for 8 to 12 hours before anesthesia.
3. When the animal is in lateral recumbency during anesthesia arranging that the occiput is
above general body level and that the head slopes so that saliva and any regurgitated
material rune freely from the mouth.
4. At the end of anesthesia, cleaning solid material from pharynx and leaving the
endotracheal tubes in trachea with the cuff inflated until the animal is in sternal
recumbency, is swallowed and can withdraw its tongue back into its mouth.
Restraining:
The majority of bovine surgeries are carried out under local anesthesia, frequently in standing
animal. Surgical procedure is made easier by use of appropriate sedative and/or restraining
“crushes or chutes”. Ropes are useful addition for restraining sedated or unsedated cattle and
anyone in cattle veterinary practice soon become expert at tying quick-release knots, tying
bowline knots for rope loops, applying Rueff’s method of casting a mature cattle by squeezing
with a neck loop two half-hitches around the body, and assembling figure of eight ties to secure
flexed front and hind limbs.

2. Electroimmobilization:
Electric devices are available to immobilize cattle by causing by muscle tetanus from application
of an electric current between electrodes at the lips and rectum. There are concerns that this
technique is neither human nor analgesic.
Sedatives usedinbovine anesthesia:
Xylazine:
Xylazine has for a long time been the most effective sedative available for cattle.
Dose rate of it in cattle is 0.02-0.20mg/kg with highest dose intended for I/M use. I/V results in
deeper sedative than I/M. Cattle assume recumbency even at lowest dose rates.
Xylazine may cause mild to severe decrease in PaO2 and moderate increase in PaCO2 in mature
cattle. Xylazine administration causes brachycardia, decreased MAP and CO, and increased
peripheral resistance.
Side effects:
It has a number of side effects that may have adverse effect on animal. It abolishes the
swallowing reflex so that regurgitation can result in pulmonary aspiration. The inability of the
cow or bull to withdraw its tongue into its mouth and swallow may persist until after the animal
regains the standing position.
Gastric motility is decreased and bloat may result while diarrhea may be observed 12-24 hours
after sedation.
Hypercalcemia persists for about 10 hours after Xylazine administration and this is associated
with decrease in serum insulin concentration.
Increased urine production occurs within 30 minutes of administration and continues for two
hours.
Detomidine:
In contrast to Xylazine, the dose rates for administration in cattle are similar to those used in
horses.
Dose rate of 0.03-0.06mg/kg I/M have been used in clinical trials, however lower doses may
produce sedation for combination with local analgesic techniques for surgery.
Elimination is mainly by metabolism as there is negligible excretion of the drug in urine. No
detomidine was detected in milk 23 hours after dosing were less than 3% of the original dose. It
increases the electrical activity of bovine uterus. Lower dose of it decreased electric activity of
uterus.

3. The pharmacological effects of detomidine in cattle are similar to those of Xylazine in that it
causes bradycardia, hyperglycemia, and increased urine production.
Medetomidine:
Deep sedation without recumbency can be obtained with I/V doses of Medetomidine,
0.005mg/kg while 0.01mg/kg produces recumbency and sedation equivalent to that obtained
with I/V doses of 0.1-0.2mg/kg Xylazine.
Acepromazine:
Acepromazine may be given in doses of 0.05mg/kg to induce mild tranquillization.
Acepromazine will decrease the dose rate of subsequently administered anesthetics and may
increase the risk of regurgitation.
Chloral hydrate:
Although some of the more recently introduced agents such as the a2 adrenoceptor agonist
Xylazine, may have some advantages, including easier administration, chloral hydrate is still a
Perfectible, acceptable, expansive sedative for adult cattle. It may be given by mouth or I/V
Injection. Young bulls present no particular difficulties provided their temperament is such that
they can be safely and effectively restrained for drenching or precise I/V injection. In many
instances the temperament of the bull is such that large doses have to be given by mouth in
order to obtain sufficient sedation to allow application to casting tackle The bull which is
running free in the yard or loose-box may be quite dangerous even to approach in such cases it
is generally water be withheld for 36 hours.
Pentobarbital:
Nervous or excitable cattle cattle may be restrained by the slow I/V injection of a 20% solution
of pentobarbital to make animal sway slightly on its hind legs behind while being able to walk
unaided, a dose of 1-2 g is needed for adult cow.
The period of recumbency is much less then if doses of chloral hydrate are administered and
recovery is not associated with struggling and excitement. More than one injection of
pentobarbital may be given during the courses of long operations.
Butorphanol:
Administration of butorphanol to healthy un-sedated cows will not predictable induce sedation
and may induce behavior changes including rest-lessness and may bellowing. Butrophanol 0.02-
0.03 mg/kg may provide sedation in cattle that are sick and may increase the quality of sedation
when administered in conjunction with xylazine.
LOCAL ANSTHESIA:
Special nerve blocks:

4. Auriculopalpebral nerve block:
This block is used to prevent eyelid closure during examination or surgery of the eye. It does
not provide analgesia to the eye or eyelids and should be used in conjunction with analgesia or
other nerve blocks for painful procedures
About 10-15ml of 2% lignocaine is injected beneath the fasica at this point.
Cornual nerve block
The horn corium and the skin around its base derive their sensory nerve supply from a branch
of the ophthalmic division of the 5th cranial nerve
The site for injection is the upper third of the temporal ridge, about 2.5cm below the base of
horn. The needle is inserted so that its point lies0, 7-1.0cmdeep immediately behind the ridge
and 5ml of 2% lignocaine solution injected.
Petersen eye block
A 22 gauge, 2.5 cm needle is used to filtrate local analgesia solution subcutaneously, about 5ml
of 2% lignocaine, within the notch formed by the supraorbital process cranially, the zygomatic
arch ventrally and the coronoid process of the mandible caudally.
Peribulbar and retrobulbar block
Retrobulbar injection is achieved by introduction of a curved needle through the skin about
1cm lateral to the lateral canthus , or through the conjunctiva the needle is first directed
straight back and away from until the point is beyond the globe and then turned inward to
penetrate the muscle cone . When no blood is obtained after aspiration, lignocaine is deposited
behind the eye.
Inverted L block
Paravertebral nerve block
Paravertebral block involves the perineural injection of the local analgesic solution about the
spinal nerves as they emerge. It offers a major advantage over use of filtration in the abdominal
wall including the peritoneum is more likely to be uniformly desensitized. Additionally, the
abdominal wall is relaxed.
Intravenous regional analgesia:
Intravenous regional anesthesia is a simple and commonly used technique to provide analgesia
of the limbs and digits. It is achieved by injectable local analgesia solution into a superficial vein
in a limb isolated from general circulation by a tourniquet. The limb distal to the site of
application of the tourniquet becomes analgesic and remains so until the tourniquet is

5. removed. The animal is restrained in lateral recumbency with or without sedation. The hairs
over a prominent vein on the relevant limb is clipped and skin prepared for injection.
In adult cattle, 30 ml of 2%lignocane is injected into vein after first aspirating blood to confirm
location of needle within the lumen of vessel. Analgesia distal to tourniquet will develop in 15-
20 minutes and persists until tourniquet is removed.
General anesthesia:
Choice of technique depends in large part on circumstances surrounding the need for sedation
or anesthesia.
Intravenous injection:
Use of an indwelling catheter is preferable to avoid perivascular injection of irritant drug, such
as thiopental or guaiphenesin, and facilitate supplement injection. A 14 gauge, 13cm catheter is
suitable for insertion in the jugular vein, although a 10 gauge catheter is better for
administration of guaiphenesin solution in bulls.
Endotracheal incubation:
There are techniques that can be used to facilitate endotracheal incubation in adult cattle. Ain
cattle up to about 300kg, incubation can be accomplished under direct vision of larynx using a
laryngoscope with a blade suitable for incubating a large dog. The animal is supported in sternal
position and laryngoscope positioned at the corner of animal’s mouth with the tip of blade on
the dorsum of tongue. The trachea is intubated with an endotracheal tube of 11-18 or 20 mm
internal diameter with a technique similar to that used in dogs.
Injectable anesthesiaagents:
1. Thiopental
2. Thiopental-guaiphenesin
3. Methohexital
4. Pentobarbital
5. Ketamine
6. Ketamine-guaiphenesin
7. Propofol
8. Tiletamine-zolazepam
Inhalationanesthesia:
Drugs used are:
1. Halothane

6. 2. Isoflurane
3. Sevoflurane and desflurane
4. Nitrous oxide
Reference:
Veterinary anaesthesia L W HALL
10TH
EDITION K W CLARKE
C M TRIM