Anesthesia II: Ruminant, Camelid, and Swine Anesthesia

Ruminant Anesthesia (Temperament and economics)

•Ruminants don't undergo general anesthesia as often as horses and small animals

•Must consider drug withdrawal times in food and milk-producing animals

Ruminants don't undergo general anesthesia as often as horses and small animals

•Don't require general anesthesia as often due to their calm nature

•Many surgeries are performed using local or regional anesthetic techniques and physical restraint

Must consider drug withdrawal times in food and milk-producing animals because of

FARAD

FARAD:

free service to veterinary practitioners to assist in the prevention of drug residues in animal-derived human foods

FARAD stands for

Food Animal Residue Avoidance Database

Local anesthesia

"L block"

Regional

paravertebral anesthesia or IVRA (IV regional anesthesia)

IVRA is also considered

Regional anesthesia performed so cow is standing while procedure being done

Ruminant Anesthesia Equipment

•Special equipment is needed because of their size

•Tilt tables, head gates, hoists, transporters

•Small animal equipment can be used for small ruminants (sheep, goats, calves)

Ruminant Anesthesia Anatomy and physiology

•Adult cattle produce 25 - 38 GALLONS of saliva/day

•Ruminants are prone to regurgitation and bloat during general anesthesia

Adult cattle produce 25 to 38 GALLONS of saliva/day

•Production generally not inhibited by anesthesia

•Aspiration risk if airway is not protected

Ruminants are prone to regurgitation and bloat during general anesthesia

•Fermentation is only slightly deceased by anesthesia

•Unable to eructate when unconscious

Ruminants: Weight Range

1. Range from a few kgs (lambs, babies) to over 1000kg (adult bull)

2. If greater than 150kg, need access to large animal equipment

Regurgitation can occur at any stage of general anesthesia, most commonly during light or deep planes

Clinical signs: distended tight abdomen, decreased BP, increased HR, decreased ventilation

Humans produce 1 - 1.5L of saliva/day =

0.3 - 0.4 gallons

Eructate =

burp

A bloated rumen can put pressure on the

diaphragm, aorta, and vena cava resulting in decreased respirations and BP

Ruminant digestion

1. Rumen

2. Reticulum

3. Omasum

4. Abomasum (true glandular stomach)

5. Known to "chew cud" - regurgitate, remasticate, etc.

Another form of restraint

What is the image showing?

Patient Preparation (Requirements)

•Use the same principles as with small animals

•Assess, prepare, and weigh the patient

•Make sure the patient is fasted to prevent bloat

•Prepare equipment for and place IV catheter

Patient Preparation (Calculations)

•Calculate the volume of each agent to give including fluid administration rates

•Review the oxygen flow rates

•Prepare equipment required to administer drugs, fluids, intubation, and monitoring equipment

•Assemble and test the anesthetic machine and ventilator

Make sure the patient is fasted to prevent bloat

Reduces the size of the rumen and decreases microbial activity (less gas production)

Calves and small ruminants =

fast from food for 12 hours and water for 8 hours

Large adult cattle =

fast from food and water for 24 hours or longer

Cannot guarantee fasting if an

emergency (non-elective) procedure

Selecting a Protocol and Equipment Prep (Factors to consider)

•Minimum patient database

•Patient physical status class

•Ill, geriatric, pediatric, & compromised patients (status classes P3 - P5) require modified protocols

•Type and duration of procedure

Selecting a Protocol and Equipment Prep (Equipment preparation)

•Make sure all equipment is present before induction

•Check circle system & ventilator of machine

•Warming equipment available for small ruminants and calves

•Crash cart for emergency drugs and equipment

Ruminant General Anesthesia

•Premedication or sedation

•May need tranquilizers for aggressive, excited, or stressed animals

•Ruminants are VERY sensitive to xylazine

•Anticholinergic drugs cause saliva to become thick and ropy ☹

Thicker mucus is

- easier to aspirate and can cause an airway obstruction

- anticholinergics are reserved for treatment of arrhythmias and for CPR

Ruminant General Anesthesia: Premedication or Sedation

•Tranquilizers generally not needed prior to IV catheterization and induction in calm and tractable animals

•May need tranquilizers for aggressive, excited, or stressed animals

Premedication is still beneficial if anesthesia needed due to

decreasing the dose of induction agent needed, muscle relaxation, and analgesia

Ruminant General Anesthesia: May need tranquilizers for aggressive, excited, or stressed animals

Acepromazine may increase regurgitation risk

Ruminant General Anesthesia: Ruminants are VERY sensitive to xylazine

Require 1/10th of the dose given to horses

IV Induction should be done in a

special padded area, in a transporter, on a tilt table

What is the goal of IV induction in ruminants?

•Get to unconsciousness rapidly with minimal injury

•Get immediate control of the airway to reduce aspiration risk

How is administration of IV induction done on ruminants?

•Double drip: ketamine and guaifenesin rapid IV to effect

•Larger ruminants: IV agent bolus

•Smaller or compromised ruminants: IV agent to effect

•Propofol works for small ruminants/camelids only, generally too expensive for adult cattle

Ruminations IV Induction and Positioning

•Sternal recumbency for intubation

•Watch for regurgitation

•If regurgitation occurs, position the head lower than the pharynx to prevent aspiration

•Check vital signs and intubate

Ruminant Endotracheal Intubation Equipment

•Appropriately sized endotracheal tubes

•Stylette (small ruminants and calves only)

•Mouth gag to hold the jaws apart (adult cattle only)

•Laryngoscope (small ruminants and calves)

•Gauze sponge to grasp the tongue (optional)

•A syringe to inflate the cuff

•Long forceps and suction

Ruminant Endotracheal Intubation Equipment: Appropriately sized endotracheal tubes

22, 24, 26, or 30-mm tube typically used for adult cattle

Ruminant Endotracheal Intubation Equipment: A syringe to inflate the cuff

-10 mL for small ruminants and calves

-60 mL for adult cattle

Ruminant Endotracheal Intubation Equipment: Prep 2 ET tubes

the anticipated size and then one size smaller

Endotracheal Intubation Equipment: Long forceps to

remove feed material if present

Endotracheal Intubation Equipment: Suction to

remove liquid that is regurgitated if present

Can apply a small amount of sterile water-soluble lube onto the tube

but is

not essential for adult cattle

Intubation of Small Ruminants & Calves (Stylette)

•Small oral opening and thick caudal half of tongue make visualization of larynx challenging

•Use of a stylette protruding beyond the end of the tube results in better visualization of the larynx

•Just using the tube on its own without a stylette, the tube will block the view of the larynx

Intubation of Small Ruminants & Calves (Advance ET tube)

•Head extended, tongue gently pulled forward, laryngoscope is placed to visualize the larynx

•Pass stylette into airway

•Pass endotracheal tube over stylette and into the larynx

•Remove stylette and inflate the cuff

The thick caudal half of the tongue is particularly seen in

goats and sheep

Calf Intubation

- Head held in an extended position. Laryngoscope directly visualizes the larynx.

- The tongue of ruminants, particularly sheep and goats, has a raised area in the caudal portion that makes correct positioning of the laryngoscope more difficult compared to small animals.

A stylette, which is pre-placed within

The tube is then advanced over the stylette into the trachea. The stylette can then be removed.

Intubation of Adult Cattle is done

blindly

Intubation of Adult Cattle is done blindly

•Mouth gag is placed and head is extended by the assistant

•Anesthetist protects endotracheal tube cuff with non-dominant hand

•Using non-dominant hand, the anesthetist palpates the larynx with the fingers and directs the endotracheal tube into the larynx, while advancing the tube with the dominant hand

•Inflate the cuff and remove the mouth gag

Adult Cattle: A mouth gag will keep the

- mouth open and protect the arm

- hand of the person intubating if the cow becomes too light

Adult Cattle: The tube is secured by

tying it to the halter or around the muzzle

Adult cattle intubation

What is this picture showing?

Maintenance of Anesthesia for Cattle (With inhalant agent)

•Small ruminants and calves: similar to small animals

•Adult cattle: similar to horses

•Ruminants tend to hypoventilate and breathe rapidly and shallowly (like a panting dog)

•Place on ventilator

Maintenance of Anesthesia for Cattle (With IV agent (TIVA)

•Reserved for short (< 20-minute) procedures in healthy, non-intubated patients

•Can also be used to extend anesthesia in an intubated patient

•Double drip is commonly used

Maintenance of Anesthesia Considerations

1. 1.5 - 2.5% isoflurane

2. Healthy ruminants typically have very few problems during the maintenance phase of anesthesia

3. BP usually well maintained, ear arties often catheterized for direct BP monitoring and blood gas analysis for long surgeries

4. This type of breathing pattern may lead to hypoxemia and difficulty keeping the patient anesthetized because of inadequate delivery of inhalant anesthetic to the lungs

5. Double drip = ketamine and guaifenesin

Patient Positioning, Comfort, and Safety

•Use same principles as for small animals

•Additional concerns

•Position ruminants with mouth lower than pharynx

•Allows drainage of saliva and any regurgitated material from the mouth, preventing build up in the pharynx

•Reduces aspiration risk

•Provide padding to prevent neuropathy and myopathy as in horses

Ruminants are not predisposed to developing

neuropathies and myopathies like horses, but still important to do as a precaution

Ruminant Anesthetic Recovery

•Patient transferred to padded recovery stall

•Monitor for signs of excessive bloating

•Keep cuff inflated or partially inflated to prevent aspiration when removing ET tube

•Leave unattended after patient is lying in sternal recumbency without support

•Don't need to withhold food or water

Ruminant Anesthetic Recovery: Patient transferred to padded recovery stall

•Place in sternal recumbency

•Make sure mouth is lower than pharynx

•Allows eructation and drainage while regaining consciousness

Ruminant Anesthetic Recovery: Keep cuff inflated or partially inflated to prevent aspiration when removing ET tube

Extubate when strong swallowing movements or coughing appear

Ruminants tend to have a

smooth recovery

Signs of excessive bloating:

visibly large, distended abdomen that feels tight to the touch

Before and after tube removal, keep the neck in a natural but slightly

extended position to protect the airway

If having difficulty removing the tube from the

remove some more air from the cuff and try again

During recovery, ruminants are maintained in sternal by

an assistant to allow for eructation

During recovery in ruminants, the head is positioned so that the pharynx is

higher than the mouth, thus allowing for drainage of saliva and regurgitation

During recovery in ruminants, folding the front limbs

underneath the patient makes it easier to keep them in sternal recumbency

Camelid Anesthesia

•Llamas and alpacas require anesthesia similar to that of small ruminants

•Copious saliva production even when anesthetized

•Have the ability to chew cud

•Prone to developing nasal congestion when in lateral or dorsal recumbency

•Obligate nasal breathers can develop upper airway obstruction during recovery

•Pseudoruminant

Pseudoruminants

have a three-chambered stomach similar to ruminants but with some key differences

Llamas and alpacas require anesthesia similar to that of small ruminants

Not TRUE ruminants, the first stomach compartment plays a similar role to the rumen

Camelids have the ability to chew cud

Common to find food material in the oral cavity at induction

1. C1 = rumen

2. C2 = reticulum

3. C3 = abomasum

Camelid Digestion

Patient Preparation

•Same as for small ruminants

•IV catheters commonly placed in jugular or cephalic veins

•Thick and tighter neck skin makes IV placement challenging

Patient Preparation: Thick and tighter neck skin makes IV placement challenging

•Also makes it a little easier to mistake the carotid artery for the jugular vein

•If a hematoma forms due to unsuccessful venipuncture, postponement of a non-emergency procedure for 24 hours may be advisable

•Tight skin tends to compress the hematoma inwards, leading to possible tracheal compression and partial obstruction

Postponement of the non-emergency procedure will allow the

hematoma to resolve some

1. Llama neck in cross section

2. Jugular and carotid can be accessed from the same angle

3. Occlude and let it fill, then it up and re-occlude to watch it fill again and confirm placement

4. Arteries have pulses

5. Trachea right nearby for compression/obstruction if hematoma present

What are the considerations of the camel and their anatomy?

Protocol, Procedure, and Maintenance

•Protocol same as for small ruminants

•Aggressive camelids may be resentful of restraints

•Ventilation easier to maintain; some may require mechanical ventilation

•Heart rate more variable than ruminants

Aggressive camelids may be resentful of restraints

May require sedation

Heart rate more variable than ruminants

Treat bradycardia with glycopyrrolate or atropine

Protocol, Procedure, and Maintenance Considerations

1. Llamas and alpacas spit

2. Usually begin with ears back and chin up as a warning

3. If you don't get the first hint, usually just blow air and saliva

4. If you STILL don't get the hint, will regurgitate stomach contents up to 10 feet

5. After spitting regurgitus, usually hang their mouth open and drool bc they don't like the taste of it

6. Maintain at 1.5 - 2.5% isoflurane

Camelid Patient Positioning

•Take care with the long, flexible neck in induction, positioning and recovery to prevent injury

•Protect the large and prominent eyes

•Position head to drain saliva and regurgitates

•Mouth lower than the level of the pharynx

Camelid Recovery

•Sternal recumbency recommended

•The head and neck should be held upright in normal position

•For labored breathing or if stridor is evident, oxygen can be delivered via a face mask

•Treat dyspnea with nasal tubes

Camelid Recovery: Head and neck should be held upright in normal position

Promotes venous drainage of any upper airway congestion that may have developed during the procedure

Camelid Recovery: Treat dyspnea with nasal tubes

•Advance small ET tube into the ventral meatus of one or both nostrils until passage of air is felt through them

•If obstruction is not alleviated, the attending veterinarian should be notified immediately

•EMERGENCY! Reintubation or tracheostomy

Like ruminants, camelids tend to remain calm and rarely

require sedation in the recovery period

1. Sternal Recumbency: hold the head and neck upright in a normal

2. Neutral position until the patient is extubated and able to hold its own neck up.

3. Right = nasal tubes

What kind of position do camelids sit in during the recovery process?

Swine Anesthesia Physical Examination

•Challenging to restrain, sedate and anesthetize due to unique species characteristics

•General observation

•Rely on patient history to determine health status

•Assessing cardiovascular status and drawing blood samples are difficult to impossible

Challenging to restrain, sedate and anesthetize due to unique species characteristics

Physical examination, sedation, IV catheterization and intubation more difficult than most other species

Swine Anesthesia General observation

•Assess respiratory rate and character

•Observe obvious problems (ex: nasal discharge)

In swine anesthesia, assessing cardiovascular status and drawing blood samples are

difficult to impossible due to squealing and non-accessible peripheral vessels

Physical examination on pigs, besides general observation, is impossible due to the

overall anatomy and restraint difficulty

Pigs typically squeal in protest when

restrained making thoracic auscultation impossible

While we could "force" them into restraint it will cause

extreme stress to the animal and the handler

Swine Premedication or Sedation

•Sedatives administered IM

•No easily accessible peripheral veins

•Thick layer of subcutaneous fat

•Must use at least a 1.5-inch needle

•Inject muscles of the neck caudal to the ear and 3-5 cm lateral to the dorsal midline

Swine Pre-Med or Sedation location described on the

neck is the most accessible site for IM injection in swine

Swine are resistant to sedative drugs

•Use a combination of a tranquilizer or sedative, an opioid, and a dissociative

•Drug combinations using a dissociative may produce sedation enough to perform short surgical or nonsurgical procedures

•TKX: Telazol®, ketamine, and xylazine

Telazol® =

Tiletamine and Zolazepam

Ketamine and Tiletamine are dissociative

1. Pig 15 minutes after IM injection of TKX

2. Blood on the neck was where the IM injection was placed