Anesthesia of Ruminants, Camelids, and Swine Ch.11 Objectives Flashcards
Describe the main physiologic and anatomic differences that influence anesthetic management of ruminants, camelids, and swine.
Ruminant, camelid, and swine anesthesia are influenced by unique physiologic and anatomic characteristics; ruminants have a specialized stomach, making regurgitation and aspiration risks prominent, while camelids and swine have particular challenges related to intubation and access to veins.
Explain how to prepare a ruminant, camelid, or porcine patient for anesthesia.
Camelids are prepared for anesthesia in the same manner as small ruminants. Intravenous catheters are commonly placed in the jugular or cephalic veins. The skin on the neck of camelids is typically thicker and much tighter than that of small ruminants. This can make it comparatively more difficult to place an IV catheter in the jugular vein successfully, and a little easier to mistake the carotid artery for the jugular vein, which may result in inadvertent carotid puncture. If a hematoma forms as a result of unsuccessful venipuncture of the neck, the tight skin tends to compress it inwards, leading to the possibility that the trachea will be compressed and partially obstructed. In the event that a hematoma develops, it may be prudent to postpone a nonemergency procedure for 24 hours to allow some resolution of the hematoma.
Select an anesthetic protocol for an ASA PS1 or PS2 adult cow, small ruminant, camelid, or pig.
For a PS1 or PS2 adult cow, small ruminant, camelid, or pig, a suitable anesthetic protocol often involves a combination of injectable drugs like xylazine, butorphanol, and ketamine, potentially followed by inhalant anesthesia with isoflurane or sevoflurane for maintenance
Explain how to intubate an adult cow, a small ruminant, calf or camelid, and a pig.
Adult cattle are intubated manually using a blind technique (Figure 11-4 and Procedure 11-4). A speculum or mouth gag is placed which prevents the cow from closing its mouth (see Figure 11-4, A). This protects the anesthetist’s arm and hand from being damaged if the cow should become light enough to chew. The anesthetist then inserts his or her nondominant hand into the mouth up to the larynx, holding (and protecting) the endotracheal tube in his or her hand (see Figure 11-4, B and C). The dominant hand is used to direct the tube. Once the anesthetist’s fingers are at the level of the larynx, the anesthetist palpates the epiglottis, reflects it forward if necessary, and directs the end of the endotracheal tube into the trachea, advancing it with his or her dominant hand. Extending the head and neck of the cow, while sometimes challenging due to its weight, is often helpful while passing the tube. Upon successful placement, the endotracheal cuff is inflated. The tube is then secured by tying it to the halter or around the muzzle in a similar manner to that used for a dog.
Small Ruminants and Calves
Intubation in these patients is accomplished as for small animal patients. The oral opening is small in these patients compared to the distance between the mouth and larynx, so visualization of the airway can be challenging. Additionally, the caudal half of the tongue is thickened which further obstructs the anesthetist’s view. Attempting to pass the endotracheal tube alone typically completely obstructs the view, making successful placement extremely challenging, and more a matter of luck than skill. Therefore using a narrow stylette that protrudes beyond the end of the tube allows better visualization of the larynx.
With the head extended by an assistant, the anesthetist places a laryngoscope to visualize the larynx. It often helps to grasp the tongue with a gauze sponge and gently pull it forward. The anesthetist then passes the stylette into the airway, taking care not to cause injury to the larynx or trachea. The endotracheal tube can then be passed over the stylette and into the larynx.
The pig may be placed in either in sternal or dorsal recumbency. Similarly to small ruminants, a straight stylette is placed within the tube such that several inches of it extend beyond the bevel of the tube. Using a laryngoscope to visualize the airway, the stylette is passed into the larynx, bypassing the diverticulum. The tube can then be gently threaded over the stylette into the trachea.
Explain the importance of proper positioning of anesthetized ruminants and camelids.
Proper positioning of anesthetized ruminants and camelids is crucial to prevent complications like bloat, regurgitation, and aspiration pneumonia, as well as nerve and muscle damage. It ensures proper ventilation and allows for easy drainage of saliva and regurgitated material. All ruminants should be positioned for surgery with the mouth lower than the pharynx to allow drainage of saliva and any regurgitated material from the mouth, preventing buildup in the pharynx, which could lead to aspiration during recovery following extubation.
Explain how to position a ruminant for recovery.
Unlike horses, ruminants are generally content to lie in sternal recumbency following anesthesia. The development of complications from anesthetic recovery is generally limited to the residual effects of bloat.
Explain how to position a camelid for recovery.
To facilitate camelid recovery after procedures, prioritize sternal recumbency or, if unavoidable, right lateral recumbency, ensuring the head is supported and positioned to allow for proper drainage of saliva and potential regurgitated material.
Explain the unique concerns and challenges when anesthetizing pigs.
Pigs are challenging patients to restrain, sedate, and anesthetize because of unique characteristics in this species that make physical examination, sedation, IV catheterization, and intubation difficult. Conscious pigs typically squeal in protest when restrained, making procedures such as thoracic auscultation impossible. The anesthetist must often rely on patient history to determine health status. Pigs also do not have readily accessible peripheral veins or arteries, making further investigation of cardiovascular status and blood sample collection very difficult or impossible without causing extreme stress to the animal, and the handler. Swine are generally considered to be the most resistant to sedative drugs of the domestic species, and many protocols for IM sedation, premedication, or total injectable anesthesia include a tranquilizer or sedative, an opioid, and a dissociative. Endotracheal intubation of swine is particularly challenging because of poor visibility, resulting from the limited extent to which the mouth can be opened, a long soft palate, the relatively narrow dental arcade, and the anatomy of the larynx and proximal trachea. Pigs can be challenging to monitor effectively because they have few palpable peripheral arteries, and their cone-shaped legs make the use of blood pressure cuffs, which are designed for the more cylindrical arms of people, difficult.
Describe the clinical signs of porcine stress syndrome.
Also known as malignant hyperthermia, porcine stress syndrome has been associated with anesthesia, particularly inhalant anesthetics
Symptoms include muscle rigidity, a rapid rise in temperature, hypercapnia, hyperkalaemia, and death. Treatment includes immediate termination of all anesthetic drugs, delivery of oxygen at high flow rates, and treatment with dantrolene.
