Vomiting in Alpaca During Capture and Chemical Immobilization

The alpaca (Vicugna pacos) is a member of the camelid family (Camelidae, order Artiodactyla), which includes dromedary camels, Bactrian camels, wild Bactrian camels, llamas, alpacas, vicuñas, and guanacos.¹ They are also known as lamoids, which are members of the South American camelid family (e.g., llamas, alpacas, vicunas, guanacos).

Alpacas are slender-bodied animals with a long neck and long legs, a short tail, a small head, and large pointed ears. They are native to the mountainous regions of Chile, Peru, and Bolivia. Alpacas are the most limited in range and the most specialized of the four species of lamoids, being adapted to marshy ground at altitudes from 13,000 to 15,700 feet. Remains of alpaca found at elevations closer to sea levels suggest that alpaca once had a wider geographical distribution and that the reduction of its range started with the arrival of the Spanish conquistadores and their introduced livestock.²

Alpacas are distinguished from llamas by their smaller size; they are the smallest of the domesticated camelid species. The weight of an adult alpaca ranges from 120 to 140 lbs, with a height ranging from 2 to 3 feet. They are even-toed ungulates with two toes on each foot and an unguligrade form of locomotion. This involves most of the weight of an animal being supported by the hoofs, as opposed to digitigrade, wherein the toes touch the ground, or plantigrade, where the entire foot is on the ground (the form used by humans.)²

There are two breeds of alpaca, known as Huacaya and Suri, although they are officially one species. The Suri alpaca has a fleece with long, thick locks which hang loose and long. Huacaya alpacas have a coat which is shorter and denser. Over 90% of alpacas are Huacaya. Their coats vary in color from black or brown through lighter shades of gray and tan to pale yellow and white.

The alpaca’s origin has long been a matter of debate that was complicated by the fact that alpacas and llamas are able to breed with one another and produce fertile offspring. This suggested that both species stemmed from guanacos, the parent species of the llama. Genetic studies however, have concluded that alpacas are the domesticated descendants of vicuñas, and that this occurred between 6,000 and 7,000 years ago.

One of the most interesting things about the alpaca is that they are comfortable in most any climate. Alpaca wool fibers are hollow, which makes it particularly valuable in that it has the ability to insulate very well, and to absorb moisture and wick it away. As a result, alpaca farming has become a worldwide cottage industry. Today, there are over 50,000 alpacas in dozens of farms across the US alone. Alpacas have been domesticated for thousands of years; it is thought even prior to the Incas, who raised and bred alpacas for wool clothing reserved for royalty.

Alpacas, Vomiting and Anesthetic Aspiration

Vomiting is one of the more common post-sedation and post-anesthesia complications in both domestic and exotic animals. It is not uncommon for a person or an animal to vomit once or twice after a surgical procedure. However, if the vomiting continues, it can be a sign of an emerging complication. A far more serious complication involves vomiting that occurs during a procedure, as this can pose grave risks due to anesthetic aspiration.

Anesthetic aspiration involves an alpaca vomiting food from its stomach during a surgical procedure, which subsequently infiltrates into the lungs. This can lead to aspiration pneumonia. While modern protocols for anesthesia and sedation in wildlife are generally safe, respiratory complications such as anesthesia-related aspiration and pneumonia can be fatal.⁴

The entry of liquid or solid material into the trachea and lungs is defined as aspiration. This occurs when patients without sufficient laryngeal protective reflexes as a result of sedation or anesthetic agents regurgitate gastric contents. “Pulmonary syndromes of differing severity can result, ranging from mild symptoms such as hypoxia to complete respiratory failure and acute respiratory distress syndrome (ARDS).”⁴ In extreme circumstances, cardiopulmonary collapse and death can occur. The related pulmonary syndromes can include acid-associated pneumonitis, particle-associated aspiration (airway obstruction) or bacterial infection. Which of these develops depends upon the composition and volume of the aspirate.

Acute intraoperative aspiration describes aspiration during a surgical procedure, and this is a potentially fatal complication with significant associated morbidity. Alpacas undergoing thoracic surgery are at increased risk for anesthesia-related aspiration, largely due to the predisposing conditions associated with this complication. Awareness of the risk factors, predisposing conditions, precautions to decrease risk and immediate management options by the veterinarian is imperative to reducing risk and optimizing outcomes associated with this complication.⁴

Technical Advancements and Risk Mitigation

The veterinary care of domestic and non-domestic hoofstock has become commonplace due to the integration of veterinary medicine in wildlife management programs, zoological collections, exotic animal ranching expansions and the private collection of wildlife species.⁵ As a result, research and wildlife veterinarians are required to amass the requisite knowledge associated with safely anesthetizing and handling animals such as alpacas. The widespread popularity of alpaca farming has necessitated that alpaca farmers keep up with alpaca health and husbandry issues, which can include aspects of sedation and anesthesia.

The sedation and anesthesia of alpacas requires the knowledge the pharmacology of the drugs being used, as well as the wide variation in dose response among sub-species of these animals. A major challenge—and one which impacts potential complications such as anesthetic aspiration—is correlating the available pharmaceutical tools with the environment and conditions, as well as the procedures and events preceding, during, and following the anesthetic event.⁶

Today, the quality of sedation, anesthesia and analgesia achievable in alpacas and other wildlife species has been made possible through the availability of new, receptor-specific and highly potent agonist-reversible pharmaceuticals and the improved knowledge of CNS receptors.

Alpacas and Chemical Immobilization

Due to their widespread domestication, camelids are often agreeable when it comes to handling, thus physical restraint and local anesthetic techniques are frequently used to provide immobility and analgesia. General anesthesia techniques are similar to those for ruminants and horses.^6,7 Regurgitation of compartment one (C1) of the stomach contents, similar to ruminants, and postoperative nasal congestion and associated respiratory distress postextubation are potential hazards associated with anesthesia. In most cases, recovery from anesthesia is generally uneventful.⁷

Monitoring core body temperature is essential in alpaca anesthesia.⁶ Until the more recent use of formulated drugs (e.g., combinations of α2-agonists such as medetomidine, detomidine, xylazine and their reversal agents), opioids were the mainstay of alpaca anesthesia in wildlife and captive care.⁵

Preventing and Managing Anesthetic Vomiting in Alpacas

Guidelines for the preparation of alpacas for anesthesia and surgery include decreasing the size and pressure in C1 before anesthesia, withholding food for 12 to 18 hours in adults and withholding water for up to 12 hours. Withholding food or water in neonates is not recommended, as this increases the risk of dehydration and hypoglycemia. Alpacas younger than one month of age rarely regurgitate during anesthesia. It is also recommended that alpacas be orotracheally intubated for procedures lasting more than 20 minutes.⁷ Positioning of the alpaca is important to reduce the likelihood of regurgitation. It is recommended that the animal’s head is kept elevated above the stomach if possible. The literature also advises against rolling an anesthetized alpaca dorsally unless an endotracheal tube has been placed.

For the prevention of anesthetic aspiration, histamine (H2) antagonists such as cimetidine, famotidine, nizatidine, and ranitidine and proton pump inhibitors (PPIs) such as dexlansoprazole, esomeprazole, lansoprazole, omeprazole, pantoprazole, and rabeprazole have been shown to be effective in increasing the pH and reduce the volume of gastric contents.⁴ Additionally, prokinetics (e.g., domperidone, metoclopramide, erythromycin and renzapride) promote gastric emptying and are believed to reduce the risk of aspiration.⁶

The first step in successful management of an intraoperative aspiration is the immediate recognition of gastric content in the oropharynx or the airways.⁴ If regurgitation has occurred, the animal’s head should be positioned with the mouth below the level of the torso. Stomach tubes can be placed in the esophagus to prevent aspiration. Orotracheal and endotracheal suctioning is indicated, either before or after orotracheal intubation, depending on whether regurgitation continues and if the airway is visible.

It is recommended that the airway be secured as rapidly as possible to prevent further contamination and to facilitate airway clearance.⁶ Flexible bronchoscopy is an important adjunct to orotracheal and endotracheal suctioning, and having a flexible bronchoscope at the ready if possible is a sound prophylactic measure. If particulate matter is present in the airway, rigid bronchoscopy may be required.^4-6