Frostbite in Llamas During Capture and Chemical Immobilization

Next to the camel itself, the llama (Llama glama) is probably the most iconic and well-known of the camel family (Camelidae), although llamas lack the characteristic back humps of Old World camelids. These animals are New World camelids, since they occur only in the Western Hemisphere. This group, which includes llamas, alpacas, vicuñas and guanacos, also goes by the term lamoids.¹

The llama is a domesticated pack animal that has been used for centuries by Andean cultures in the mountains of South America. Like some lamoid species such as the alpaca, llamas have been so widely domesticated that there are no longer llamas occurring in the wild.

According to the fossil record, the forerunners of modern llamas evolved in North America some 40 million years ago and migrated to South America approximately 3 million years ago. Other prehistoric camelids migrated west via the Bering land bridge, later becoming modern camels. Scientists believe that at the end of the last ice age (approximately 10 thousand years ago) the ancestors of llamas became extinct in North America.¹

Today, the majority of llamas live in Argentina, Bolivia, Chile, Ecuador, and Peru. Over the last 40 years, South American exporters have been selling llamas to farmers and breeders around the world, primarily North America, Australia, and Europe. As a result, llamas have become popular among farmers, breeders, and exotic pet enthusiasts.²

The llama is the largest of the New World camelids, which is why it is a so widely engaged as a pack animal across its Andean range. Llamas come in a number of colors, such as brown, white, black, grey, piebald or spotted. The soft inner hairs of their fleece are highly valued for clothing and knitting, while the coarser outer hairs of their fleece are used to make ropes, rugs, and handicrafts. Adult llamas range in height from 5-1/2 feet to 6 feet tall and weigh between 290 to 440 pounds.¹ They have short tails and large, banana-shaped ears. Their feet are narrow and padded on the bottom, allowing these animals to comfortably navigate rough mountain terrain.²

Llamas are social animals that do very well living in herds. Female llamas are called “dams” or “hembras,” while males are called “studs” or “machos.” Like horses, castrated males are known as “geldings.” Llamas communicate through a variety of humming sounds, and it is said that they can distinguish between different vocalizations. When they recognize danger, llamas will let out a shrill moan to alert members of the herd. In South America, llamas are sometimes used as livestock guards for flocks of sheep, with geldings typically being trained for these missions.³

Strangely, despite the llama’s pleasant demeanor, it has been recommended that llama owners and farmers refrain from oversocializing these animals with humans, since it can lead to something called “berserk llama syndrome.” This is reported as a psychological condition that affects male llamas when they become too comfortable with humans, see them as fellow herd members and try to dominate them.³

The llama’s diet consists mainly of grass; they regurgitate their food and chew it as cud. Unlike cows however, llamas are pseudo ruminants with a three-chambered stomach (unlike true ruminants such as cows, which have a four-chambered one). Llamas have a very long large intestine which allows them to go for long periods without water.² Llamas breed in the late summer and fall. Their gestation period is approximately 11 months, after which the female gives birth to one young.³ Llamas have an average lifespan of 20 years.

Understanding Frostbite in the Llama

Frostbite is classified as a freezing injury that is divided into four overlapping phases:

• Prefreeze
• Freeze–thaw
• Vascular stasis
• Late ischemic.⁵

Prefreeze consists of tissue cooling, vasoconstriction and ischemia and without ice crystal formation. The freeze–thaw phase is represented by the intracellular or extracellular formation of ice crystals. This can give rise to protein and lipid derangement, cellular electrolyte shifts, cellular dehydration, cell membrane lysis, and cell death. In the vascular stasis phase, vessels fluctuate between constriction and dilation, and blood may leak from vessels or coagulate within them. The late ischemic phase results from progressive tissue ischemia and infarction from a cascade of events (e.g., inflammation, vasoconstriction emboli).⁵

The normal body temperature for llama adults and crias is from 99.5 to 102 degrees Fahrenheit, although the temperature of newborns can run slightly higher. The chemical immobilization of llamas can require extended periods of immobility in the captured animal. Hypothermia is an inherent risk to any animal undergoing chemical immobilization regardless of the ambient temperature, and frostbite is an even greater risk during the winter months.^6,7

Frostbite Classifications

Frostbite is classified into four degrees of injury which follow the classification system for thermal burns. Early stage frostbite is different than frostnip, which is a superficial nonfreezing cold injury associated with intense vasoconstriction on exposed skin. Frostnip may precede frostbite, however.⁷

• First-degree frostbite causes numbness and erythema. A white or yellow, firm, and slightly raised plaque may develop in the area of injury. There may be slight epidermal sloughing and mild edema is common.
• Second-degree frostbite injury causes superficial skin vesiculation. A clear or milky fluid will be present in superficial blisters surrounded by erythema and edema.
• Third-degree frostbite causes deeper hemorrhagic blisters, indicating that the injury has extended into the reticular dermis and beneath the dermal vascular plexus.
• Fourth-degree frostbite extends completely through the dermis and involves the comparatively avascular subcutaneous tissues, with necrosis extending into muscle and bone.⁷

Preventing Frostbite in the Llama

When tissue heat loss exceeds the ability of local tissue perfusion to prevent freezing of soft tissues, frostbite injury occurs. Since frostbite is usually preventable but often not improved by treatment, frostbite prevention is considered far better than frostbite treatment. Nascent medical issues and the chemical immobilization event itself can increase the risk of frostbite, so prevention should address both medical and environmental aspects. The team in the field must ensure adequate perfusion and minimize heat loss to prevent frostbite.⁷

Preventive measures to ensure local tissue perfusion include:

• Maintaining core temperature
• Maintaining body hydration
• Minimizing the effects of any comorbidities
• Covering head and body to insulate from the cold
• Minimizing any blood flow restriction
• Using supplemental oxygen in hypoxic conditions⁷

Additionally, steps should be taken to minimize exposure of the llama’s tissues to cold, such as:

• Avoid environmental conditions that predispose to frostbite (e.g., below -15°C, even with low wind speeds)
• Protecting exposed skin from moisture, wind, and cold
• Avoiding perspiration or wet extremities
• Increasing insulation and skin protection
• Using chemical and/or electric warmers to maintain peripheral warmth (These should be close to body temperature before being activated and must not be placed directly against skin or constrict flow)
• Regularly checking the animal’s temperature
• Recognizing frostnip or superficial frostbite before it becomes more serious
• Minimizing duration of cold exposure⁷

Treatment of Frostbite in the Llama

If a llama’s body part is frozen in the field, the frozen tissue should immediately be protected from further damage.⁷ If environmental conditions are such that thawed tissue could refreeze after being thawed, it may be safer to keep the affected part frozen until a thawed state can be maintained.

Hypothermia can accompany frostbite; it also causes peripheral vasoconstriction that impairs blood flow to the extremities. Mild hypothermia may be treated concurrently with frostbite injury. Moderate and severe hypothermia should be treated effectively before treating frostbite injury.^7,

NSAIDs Treatment

Nonsteroidal anti-inflammatory drugs (NSAIDs) block the arachidonic acid pathway and decrease production of prostaglandins and thromboxanes. These can lead to vasoconstriction, dermal ischemia, and further tissue damage.^6,7 No studies have demonstrated that any particular anti-inflammatory agent or dosing is clearly related to outcome, however. One rabbit ear model study showed 23% tissue survival with aspirin versus 0% in the control group.⁷ However, aspirin theoretically blocks production of certain prostaglandins that are beneficial to wound healing.

Hydration Treatment

Frostbite injury can lead to vascular stasis, so the appropriate hydration and avoidance of hypovolemia are important for frostbite recovery. Intravenous normal saline should be given to maintain normal urine output. IV fluids should optimally be warmed before infusion and infused in small, rapid boluses, as slow infusion can result in fluid cooling and even freezing as it passes through tubing. Fluid administration should be optimized to prevent dehydration.⁷

Low Molecular Weight Dextran (LMWD) Treatment

Intravenous low molecular weight dextran (LMWD) decreases blood viscosity by preventing red blood cell aggregation and formation of microthrombi and can be given in the field once it has been warmed. In some animal studies, the extent of tissue necrosis was found to be significantly less than in control subjects when LMWD was used, and was more beneficial if given early.⁷ The use of LMWD has not been evaluated in combination with other treatments such as thrombolytics. LMWD should be given if the llama is not being considered for other systemic treatments, such as thrombolytic therapy.⁷