Camelidae and Cervidae Fractures – NAVLE Study Guide

Overview and Clinical Importance

Fracture management in camelids (llamas and alpacas) and cervids (deer, elk, and related species) represents an important but less frequently tested area on the NAVLE. These species present unique anatomical considerations, management challenges, and treatment options that differ significantly from more commonly encountered domestic species.

South American camelids are considered excellent orthopedic patients due to their relatively low body weight (typically 35-70 kg for alpacas, 90-160 kg for llamas), quiet temperament, ability to ambulate on three legs postoperatively, and tolerance of external coaptation devices. Cervids, however, present significant challenges due to their flighty nature, stress susceptibility, and regulatory considerations regarding capture and treatment.

Camelid Musculoskeletal Anatomy

Llamas and alpacas possess several anatomic peculiarities that differentiate them from other large animals and influence fracture management decisions.

Key Anatomical Features

Fused Metacarpals and Metatarsals: Like ruminants, camelids have fused third and fourth metacarpal/metatarsal bones forming a single "cannon bone." However, the distal ends diverge to articulate with two separate digits. This fusion provides strength but creates a unique fracture pattern consideration.

Digit Structure: Camelids possess two weight-bearing digits (III and IV) on each foot. The fetlock joint is formed by the fused metacarpal/metatarsal bones, two pairs of proximal sesamoid bones, and two proximal phalanges. Unlike horses and cattle, the second and third phalanges (P2 and P3) are horizontal to the ground and both weight-bearing.

Soft Foot Pads: Camelids have soft foot pads rather than hooves, making them "pad-footed" (Tylopoda). This anatomical feature affects weight distribution and requires consideration during casting and external fixation.

Complete Ulna: Unlike horses where the ulna is fused to the radius, camelids retain a complete, separate ulna that extends the full length of the radius. This is clinically significant for carpal valgus deformities and certain fracture configurations.

Fracture Distribution in Camelids

The following table summarizes fracture distribution based on retrospective studies:

Etiology of Camelid Fractures

Dystocia-related trauma: Common in neonates; often affects humeral or femoral bones during difficult deliveries.

Inter-male aggression: Fighting males engage in chest butting, biting, and striking. Humeral fractures are particularly associated with male aggression behaviors.

Environmental trauma: Fence entanglement, kicks from other animals, or falls can cause fractures at any location.

Metabolic bone disease: Nutritional deficiencies (vitamin D, calcium, phosphorus) can predispose to pathologic fractures, particularly in young animals.

Fracture Fixation Techniques in Camelids

External Coaptation (Casts and Splints)

Simple casting is appropriate for stable, closed fractures of the distal limb, particularly in young animals. Fiberglass casting material is preferred due to its strength and water resistance. Key principles include:

• Immobilize joints above and below the fracture
• Adequate padding to prevent pressure sores (particularly over bony prominences)
• Regular monitoring for cast complications (swelling, discharge, odor)
• Cast changes every 2-3 weeks in growing animals

Transfixation Pin Casting (TPC)

Transfixation pin casting is a form of external skeletal fixation that combines transcortical pins with fiberglass casting. This technique is highly effective in camelids and small ruminants due to their size and temperament.

Technique: Two or more Steinmann pins or centrally-threaded transfixation pins are placed transcortically through bone proximal (and sometimes distal) to the fracture site. The pin ends are incorporated into a fiberglass cast that extends to the ground, suspending the limb and transferring weight-bearing forces from the bony column to the cast.

Advantages and Disadvantages of Transfixation Pin Casting

Internal Fixation

Internal fixation methods used in camelids include:

Bone Plating: Dynamic compression plates (DCP) and locking compression plates (LCP) provide rigid fixation. Due to camelids' smaller size compared to horses, implants designed for small animals, horses, or humans can be used.

Lag Screw Fixation: Appropriate for oblique and spiral fractures; can be combined with plating or used alone for simple configurations.

Intramedullary Pinning: Rush pins or Steinmann pins used for certain femoral and humeral fractures, particularly in young animals with physeal fractures.

Interlocking Nails: Provide rotational stability for comminuted diaphyseal fractures; well-suited for femoral fractures.

Treatment Outcomes by Fixation Method

Amputation as a Treatment Option

Camelids tolerate amputation remarkably well due to their ability to ambulate on three limbs. Amputation should be considered when:

• Irreparable neurovascular damage has occurred
• Severe osteomyelitis is present
• Open, severely contaminated fractures with extensive soft tissue damage
• Economic constraints prevent other repair options
• Failed surgical repair with non-union or chronic complications

Prosthetic devices can be fitted and are generally well-tolerated by camelids, potentially improving mobility and quality of life for amputees.

Complications of Fracture Repair

Complications are common following orthopedic surgery in camelids, with some studies reporting rates as high as 87%. Understanding these complications is essential for client communication and case management.

Cervidae (Deer, Elk, Moose) Fractures

Cervids present unique challenges for fracture management due to their flight response, susceptibility to capture myopathy, and regulatory considerations. Treatment decisions must balance animal welfare with practical limitations.

Clinical Context

Wild Cervids: Fracture treatment in wild deer is generally not recommended due to the extreme stress of capture and handling, which can lead to capture myopathy and death. Wildlife rehabilitation permits often exclude cervids, particularly in areas with chronic wasting disease (CWD) concerns.

Captive/Farmed Cervids: Privately owned cervids (deer farms, game ranches) may be candidates for fracture treatment. These animals are more habituated to human contact, though stress management remains critical.

Key Differences from Camelids

Treatment Approaches for Cervids

Conservative Management: For wild or semi-wild cervids with non-articular fractures above the tarsus/carpus, conservative management (confinement, restricted activity) may allow natural healing. Many deer can survive and function with healed but malunioned fractures.

External Coaptation: Bandage splints and casts can be used for distal limb fractures in fawns and habituated cervids. General anesthesia should be avoided when possible due to myopathy risk; sedation with careful monitoring is preferred.

Internal Fixation: Rarely performed due to stress concerns, but may be considered for valuable breeding animals. Intramedullary pins with cerclage wires have been used successfully for tibial fractures.

Amputation: Distal limb amputation with rapid release back to the wild may be considered for irreparable fractures in cervids destined for release. This approach minimizes captivity time.

Anesthesia and Analgesia Considerations

Camelid Anesthesia

Camelids can be safely anesthetized for fracture repair using protocols similar to small ruminants. Key considerations include:

• Pre-anesthetic fasting (12-24 hours for adults) to reduce regurgitation risk
• Alpha-2 agonists (xylazine, medetomidine) provide reliable sedation
• Ketamine combinations commonly used for induction
• Inhalant anesthesia (isoflurane, sevoflurane) for maintenance
• Positioning in sternal recumbency when possible to reduce aspiration risk

Analgesic Options

Cervid Sedation

For cervids requiring treatment, chemical immobilization is essential. Long-acting neuroleptics (haloperidol, azaperone) may help reduce anxiety during captivity. Key points:

• Avoid prolonged chemical restraint due to myopathy risk
• Medetomidine-ketamine combinations commonly used
• Atipamezole reversal allows rapid recovery
• Minimize handling time and stimulation

Memory Aids

CAMELID = C.A.M.E.L.I.D.

Calm temperament - excellent orthopedic patients

Ambulate on three legs postoperatively

Metacarpals/metatarsals III and IV fused (like ruminants)

External coaptation well tolerated

Light body weight - can use small animal/human implants

Internal fixation shows superior outcomes

Digits two (functional), ulna complete (unlike horses)

DEER = D.E.E.R.

Difficult patients - flighty, stress-prone

Exertional myopathy risk with capture/handling

Early release priority - minimize captivity time

Regulatory issues - CWD testing, rehabilitation restrictions

Prognosis and Return to Function

Camelid Prognosis

Overall prognosis for camelid fractures is favorable when appropriate treatment is pursued:

• Survival to discharge: approximately 79-92%
• Return to intended use: 65-85% depending on fracture type
• Owner satisfaction: generally high

Negative prognostic factors: Open fractures, increased body weight, articular involvement, comminution, delayed presentation, and fractures involving two joints.

Cervid Prognosis

Prognosis for cervids is guarded due to temperament and management challenges:

• Wild cervids: Generally poor prognosis for surgical intervention
• Captive/farm cervids: Better prognosis, especially for fawns
• Natural healing: Surprisingly common - deer can survive with malunioned fractures