An ox is a castrated male of any breed of cattle that has been trained to work as part of a team, having been paired at a young age (Figure 61-2). Castrated males are more docile and grow larger than do intact males; thus they are able to carry or pull heavier loads. Oxen were the mainstay for agriculture and for transporting people and goods in North America before establishment of the transcontinental railroad in 1869. They are still used for these purposes in many places in the world where access to mechanized agriculture is limited.

FIGURE 61-2 Oxen.

The yak is the primary draft animal for native people living at high elevations in Central Asia and China (Figure 61-3). Yaks and their handlers are frequently employed by trekkers in these locales.

FIGURE 61-3 A yak.

The water buffalo is the beast of burden in wet environments (marshes, rice fields, jungles) of Southeast Asia.

The pre-trip care of oxen, yaks, and water buffalos is essentially the same. It is difficult to generalize about immunizations because there are significant regional differences in infectious and parasitic diseases. These animals should receive the general vaccines administered to them in their native countries. If there are known endemic infectious diseases, for which there are vaccines, in the region where the trek will take place, arrangements should be made to have vaccination completed at least a month before the trek. Routine evaluation for parasites and necessary therapies should likewise be done at least 2 weeks before a trek.

Elephants

Asian elephants have been used for carrying loads, harvesting timber, carrying people, and engaging in warfare since antiquity (Figure 61-4, online). They are also used as beasts of burden for wilderness treks in forested areas of Southeast Asia, India, and southern China. Elephants are often considered to be domestic animals, whereas in reality they are wild animals that respond to taming and training to produce reliable beasts of burden that are useful for many tasks. Elephants should only be used under the care and guidance of a skilled handler, called a mahut or ozzie.

FIGURE 61-4 An elephant on trek.

Elephants should be immunized against tetanus (toxoid) and in endemic areas against rabies using a killed vaccine. Parasites may be important regionally.

Dogs

Dogs are routinely immunized against canine distemper, parvovirus, Bordetella (if they will be exposed to other canines), canine adenovirus, leptospirosis, and rabies. Dogs should be on a heartworm preventative medication if traveling in a mosquito endemic area. Vaccinations should be current. It should be noted that the leptospirosis vaccine does not protect against all serovars of this disease, so caution should still be taken when animals will be drinking standing water that could carry this disease. A check should be made for internal parasites and fleas so that appropriate action may be taken. Although dog fleas do not permanently infest humans, they bite and may cause mild to severe local dermal reactions in sensitive individuals. There are several good products, such as pyrethin-containing dusting powder, that can be used to treat or prevent flea infestations and that can be supplied by a veterinarian (who will know the most current and effective products) prior to an outing. It should be noted that it is unlikely that the fleas involved in the sylvatic plague cycle will infest a dog (they do, however, infest prairie dogs). Because external parasites, particularly ticks, can be carriers of multiple diseases, a flea and tick preventative (e.g., Frontline with methoprene, or Frontline Plus with fipronil) is also highly recommended and can be purchased from a veterinarian prior to the trip.

Cats

Like other animals on a trek, cats should have a pre-trip physical examination, with special emphasis on fleas in the hair coat and evidence for internal parasites, such as Toxoplasma gondii oocysts or ascarid (e.g., Toxascaris leonina and Toxocara cati) ova, in the feces.

Vaccinations, including protection against rhinotracheitis, feline calicivirus, and feline panleukopenia, should be current. Rabies vaccination should be current. Although housecats may be vaccinated against other agents, these are the only diseases that are of significance to trekkers.

Rest

Support animals require less sleep than do human trekkers. Horses can sleep while standing because they have a special locking mechanism of the tendons and ligaments of the limbs. Horses may also lie in sternal or lateral recumbency. Llamas, elephants, and camels usually rest in a sternal position but may also assume lateral recumbency.

Llamas enjoy taking a dust bath by rolling in dirt soon after packs are removed. A few may even try to roll with the pack in place. Elephants enjoy a water bath when available.

Watering and Feeding

All animals require daily access to potable water. It is not practical to filter or disinfect water for large animals, but this may be considered in extremely filthy conditions. Dogs may be susceptible to giardiasis, and theoretically, it is desirable to provide filtered water for them. However, preventing a free-running dog from drinking from a stream or lake is virtually impossible. Heavily mineralized or silted water may be as unpalatable for animals as for humans and may cause similar gastrointestinal upsets.

The basic fluid requirement for a horse or other large trek animal is approximately 40 mL (1.5 oz)/kg/day, or 18 L (5 gal) for a 450-kg (1000-lb) horse. With work and heavy sweating, the requirement may be tripled. Horses sweat profusely and should be given the opportunity to drink along the trail. Llamas and burros may require one-third less water than a horse. However, although they tolerate dehydration better than do other species, they function better if well hydrated. Some llamas refuse to drink until evening. The camel is noted for its ability to tolerate a number of days (2 to 7) without drinking water.

A 450-kg (1000-lb) camel may lose 25% of its body weight via dehydration. That amounts to 114 kg (250 lb). A 114-kg (250-lb) water loss would equal approximately 114 L (30 gal) of water. The camel is unique in that it can drink, at one time, sufficient water to replace the loss without disastrous effects. A human being would be close to death at a 12% loss of body weight caused by dehydration and could not be orally rehydrated all at once.

Feeding Horses, Mules, and Burros

Horses consume approximately 2% of their body weight daily (or 9 kg [20 lb] of total feed for a 450-kg [1000-lb] horse). When the animals are working hard, one-third of this amount should be concentrates (grains such as rolled oats, barley, or cracked corn; or mixed grains and molasses in loose or pellet form). If forage is unavailable, alfalfa pellets should be carried. Animals should become accustomed to eating pellets before the journey begins. Concentrates should be reduced on days when the animals are not working.

Feeding Llamas

Llamas require only 1.0% to 2% of their body weight in food daily. Given the opportunity, llamas will graze and browse to satisfy their requirements. Many packers carry a supplement mixture consisting of one-half alfalfa pellets and one-half grain mix (the same as for horses), used as required. Some llamas are reluctant and must be trained to eat pellets or grain. Training should take place at home, before the trek.

Feeding Oxen, Yaks, and Water Buffalos

These animals are grazers and are able to subsist on native grasses better than can horses. Seasonal availability of forage should be considered during the planning stage of a trek. If necessary, supplements should be carried as part of the trek supplies. Concentrates (such as a mixture of corn, oats, and barley; or omnivore pellets such as those fed to zoo ungulates) should suffice. Pelleted alfalfa is also compact and easy to feed and carry. Trek animals should become accustomed to eating the supplement before the trek begins. Time must be allocated during daylight hours for these animals to graze if they are to subsist on native forages.

Numerous wild plants and trees contain chemicals that may make the plant unpalatable or even toxic. If the trek animals are in their native habitat, they may be able to discern toxic plants. More often, a person knowledgeable about the plant life in the area should scout out the intended area for undesirable plants. If supplements are to be fed, this should take place before hungry animals are turned loose to graze.

Animals may be tethered to a stake or a picket line in an area intended for grazing. Some handlers rely on hobbles, but the author has had personal experiences with animals learning to cope with hobbles and traveling some distance away from a campground.

Feeding Elephants

Trek leaders must rely on the elephant handler to know what is required for elephants. Elephants are both grazers and browsers. Given suitable foliage in an area, they will forage adequately if given time to feed.

Feeding Dogs and Cats

A dog should be accustomed to high-quality dry dog food. Many sled dogs are on a raw diet. The quantity fed should increase by one-half when the dog is exercising. A cat should be accustomed to eating dry cat food. Avoid feeding scraps from trekker’s food.

Emergency Restraint

It is assumed that one or (preferably) more persons on the trek are acquainted with the general care and handling of any domestic species involved in the expedition. Methods of haltering and leading are specific for each animal. Securing animals at night may require hobbling or tethering. Skill and experience are necessary to accomplish this without risking injury to the animal or handler. Animal handlers should be able to examine and clean the feet and hoofs of their charges. All people who deal with the animals should know how to create a halter tie (Figure 61-5) so that a safe and secure tie can be made at rest stops or whenever an animal is to be tethered. Knowledge of temporary rope halter construction is desirable in the event of loss or breakage of halters (Figure 61-6).¹¹

FIGURE 61-5 Sequence of steps to create a halter tie.

FIGURE 61-6 Temporary rope halters.

Horses, Mules, and Burros

Large animals may inflict serious or lethal injuries on people. When in pain or panicked, they may not respond even to their customary handlers. If a horse is down and entangled in rope, wire, or bushes, it should be approached from its back and its head held down until it can be extricated. The handler should stay out of the reach of both fore and hind limbs.¹¹

A horse’s defensive and offensive actions are to strike with the forelimbs, kick forward and backward with the rear limbs, and bite. The safest place to stand is close to the left shoulder. A person examining the feet and legs of a standing horse should keep his or her head above the lower body line to avoid having the horse reach forward with a rear limb and striking it.

Additional restraint for painful procedures may be accomplished by grasping one or both ears of the horse. The method of “earing” a horse is as follows: Stand at the left shoulder and grasp the halter or lead rope with the left hand. Place the right hand palm-down with the fingers together and the thumb extended, on the top of the neck. Slide the hand up the neck until the thumb and fingers surround the base of the ear (Figure 61-7). Squeeze tightly, but do not twist the ear. The horse usually tries to pull away as the ear is grasped. Be prepared to move with the horse while maintaining a firm grip.

FIGURE 61-7 Earing a horse.

Llamas

Pack llamas are usually docile. Although most allow their feet to be lifted for inspection or treatment, some try to lie down. One or two people should stand on the side opposite the limb being lifted, or the llama should be placed next to a tree or large rock to prevent the animal from moving away. The limb should be firmly grasped. It may be necessary to provide semisupport to the body if the animal tries to lie down.¹²

If a llama refuses to get up, the rear limbs may be pulled out behind it. If it still refuses to rise, an injury or illness that inhibits rising should be suspected.

Only rarely does a llama “spit” against an annoyance. The spit is actually stomach contents, the foul odor of which remains until thoroughly washed off. Spitting is usually directed toward other llamas to express displeasure, but handlers may be caught in the crossfire. If a llama becomes irritated during an examination or treatment procedure, spitting can be controlled by draping a cloth over the nose and tucking the top around the nose piece of the halter. Llamas also dislike the odor of stomach contents on their noses. Llamas can be “eared” in a manner similar to that used for horses.¹¹

Camels

A knowledgeable and experienced handler should be in charge of camels. Restraint procedures should be left to him or her except in emergencies. Camels used for trekking should be trained to be led and to kush (lie down) for ease of loading baggage and people. Sturdy halters and lead ropes should be supplied for each camel. Persons without experience with camels must appreciate that camels are capable of kicking or striking with all four limbs. The lack of a hind flank fold frees the limb to swing in an extended arc. Keep in mind that a camel is able to scratch its ear with a hind foot. It also has a formidable array of canine teeth and is capable of opening the mouth widely to bite. Known biters should be kept muzzled except when eating. An unhappy camel may exhibit its displeasure by regurgitating stomach contents (called spitting) on a person.

Most examination and treatment procedures should be carried out with a camel in the kushed position. Camels may be ridden or packed with equipment and supplies. When ridden, they are usually guided by voice commands or touching with a goad or whip. A single lead rope is either attached to a halter or to a wooden peg inserted through the lateral side of the nostril. Camels are usually secured at night by tethering to a picket line or a stake. The tether may be attached to a sturdy halter or by a hobble on one front ankle. The method employed will depend upon the area of the world where the camel is being used and according to the culture of the camel handler.

Oxen, Yaks, and Water Buffalos

These animals are usually docile and easy to handle. They should be trained (usually from the time they are juveniles) to respond to voice commands or touching with a goad (stick) on a specific area of the body or limbs. Oxen may be driven by a handler walking alongside or by leading. If two animals are yoked together to pull a cart or wagon, the handler walks beside the animal on the left. Oxen are not usually trained to allow a foot to be picked up as would be done with a horse. Any examination or treatment of the bottom of the hoof may necessitate casting the animal (forcing it to lie down). This may be easily accomplished by using a half-hitch method (Figure 61-8).

FIGURE 61-8 Half-hitch method of casting an ox.

The animal is tied securely by the head to a solid structure (tree, post, fence or large rock) near the ground. The procedure requires the use of a rope 6 to 9 m (20 to 30 feet) long and 1.27 cm (0.5 inches) in diameter. Tie a loose bowline around the neck of the animal. Then place a half hitch behind the forelegs (see Figure 61-8). Place another half hitch over the caudal aspect of the rib cage. Take up all slack in the loops, so that when pulled from behind, the half hitches will not slip caudally but will tighten on the chest wall. One or two persons begin to exert a steady pull on the rope from behind the ox, and should be persistent. If the ox spreads its hind legs and refuses to go down, place a short rope hobble on the hind legs to prevent the straddle. Then renew the pressure. The pressure exerted on the chest will cause the ox to become recumbent. Tie the forelimbs together and the hindlimbs together; then stretch them forward and backward.

Dogs and Cats

Dogs usually accompany their owners, who are able to handle them under difficult circumstances. If mildly painful medical procedures must be performed, the head and mouth should be secured. The dog’s body can be securely held against the handler’s body by reaching across the back of the dog and grasping the base of the neck while pulling the opposite shoulder with the elbow toward the handler. The other hand should tuck the dog’s head under the handler’s arm. To secure a dog in lateral recumbency, it is vital to control the down-side legs as well as the head to prevent the dog from being able to effectively rise.

Alternatively, a muzzle can be constructed from a nylon cord or even a shoelace. A loop should be formed with an overhand knot on one side. The loop is placed over the muzzle of the dog, with the knot on top, and tightened (Figure 61-9). The ends of the loop should be wrapped around the muzzle, crossed beneath the jaw, and tied behind the ears (Figure 61-10).

FIGURE 61-9 Placing a muzzle on a dog.

FIGURE 61-10 Completed muzzle on a dog.

Cat restraint is accomplished by wrapping the cat in a towel. Grasp the cat by the nape of the neck close to the head. Place the cat on an outstretched towel and press down on the back while another person begins to roll one end of the towel over the cat and continues to roll the cat into the towel. A limb may be withdrawn from the towel roll. Chemical immobilization of a cat is easily accomplished using ketamine HCl at a dose of 10 to 20 mg/kg administered intramuscularly or subcutaneously.

Intramuscular injections are administered in the paraspinal muscles to either side of the lumbar spine or in the muscles of the upper rear lumb, making note that injecting in the upper rear limb may cause inadvertent sciatic nerve injury. For subcutaneous injections, grasp a fold of skin on the dorsal aspect of the neck just in front of the shoulders. Lift the skin and inject beneath the tented skin.

Conditions Common to All Species

Support animals may injure each other or their human handlers, or they may spread disease (such as ringworm or lice). Human injuries are discussed in Chapter 21.

Trauma

Contusions, abrasions, and lacerations are the most common ailments encountered in support animals. Falls, stumbling on sharp rocks, brushing against branches, and encounters with other animals are frequent causes of injury. Such wounds should be handled like similar human injuries. Hair or wool should be trimmed from the margins of wounds before treatment or suturing to prevent matting with exudate. The skin may be sutured with any suture material suitable for humans. Antibiotics are not necessary unless vital structures, such as synovial or serosal membranes, are exposed.

Rope burns may occur in all species, but they are more likely to occur in horses because they tend to struggle against entanglements, and their skin is quickly burned by abrasive action. Therapy is similar to that for human burns. Thermal burns are unlikely unless animals are caught in brush or forest fires.

Foot, Hoof, and Nail Problems

Foot injuries may incapacitate an animal and possibly the expedition.^7,¹² The hoof of the horse covers the distal extremity and the third phalanx (P-3). The specialized horn of the hoof and nail is roughly analogous to the human nail. Horses are digitigrade, walking on the tip of P-3 (see Figure 61-1). In llamas, P-2 and P-3 lie in a horizontal plane within the foot, with only P-1 in the vertical position. The nails of the llama and dog are inconsequential in weight bearing, but if torn or contused, become extremely painful.

The weight-bearing surface of the horse’s hoof contains the firm sole and more flexible frog, overlying soft fibroelastic tissue called the digital cushion. Dogs have footpads similar to those of llamas.

Oxen, yak, and water buffalo may require hoof trimming just as do horses, mules, and donkeys. Oxen are rarely shod with metal shoes, but it is possible. Any trimming of the hooves should be performed at least a month before a trek. The feet, muscles, tendons, and ligaments should be conditioned for the trek by walking on terrain similar to that of the trek.

The structures of the foot are subject to contusions, abrasions, lacerations, and penetration by foreign bodies (such as nails, stones, and sticks). Segments of the hoof wall and nail may be avulsed, exposing the sensitive laminae. Infection may invade the foot and undermine the outer layers, with abscess formation. Not all lesions are visible. Stone bruises of the sole or frog of a horse may be evident only when pressure is exerted on the site of the contusion. Foreign body penetrations and abscesses may cause reluctance to place any weight on the limb. The penetrating object may have been withdrawn or still be in place; in either case, a discolored tract leads to the depth of the wound. Erosions and ulcerations of the footpads are common in unconditioned dogs and llamas. Dogs working in ice, snow, mud, and water may suffer from maceration, cracks, erosions, lacerations, and frostbite.

Foot and limb trauma is accompanied by varying degrees of lameness (limping). It may be difficult to establish which leg is painful, but the principles are similar to evaluation of such pain in humans, with the obvious differences of two extra limbs to evaluate and the animal’s inability to communicate.

Cellulitis may develop on the limbs or body. The signs include heat, swelling, and redness and are the same in all species, as is therapy.

Therapy for foot injuries includes providing drainage of infected lesions, disinfection, and protection of exposed sensitive structures. Antibiotics are not indicated for most wounds unless a joint surface is exposed. It may be necessary to bandage the foot to provide protection while in camp and to fashion special shoes or boots to keep an animal functioning on the trail. Special booties are available commercially for dogs, but a temporary moccasin can be constructed from soft leather (such as the leather used by craftspeople to make moccasins) or duct tape.

Hyperthermia (Heat Stress, Heat Exhaustion)

Hyperthermia is elevation of the core body temperature above normal limits. Chapters 10 and 11 discuss hyperthermia in humans, and it is important to recognize that animals associated with a trek may become overheated as well.^12,¹³

Etiology

The primary cause of hyperthermia in pack animals on treks is excessive muscular exertion, especially during periods of high environmental temperatures and high humidity. Animals that struggle for prolonged periods in swampy terrain or in snow or mud may also produce excessive heat. Although high ambient temperature is a contributing factor, excessive muscle exertion in any climate may cause elevation of body temperature. Pack animals may also develop fever as a result of infectious diseases. Dehydration from inadequate supplies of potable water exacerbates the problem.

Inadequate physical conditioning is a common problem and contributes to a cumulative heat load. Other contributing factors include lack of salt in the diet, preexisting cardiovascular insufficiency, obesity, and trauma.

Clinical Signs

Signs vary according to species and the stage of hyperthermia, but all affected animals have increased heart and respiratory rates, usually accompanied by open-mouth breathing. Rectal temperatures may vary from 41.1° to 43.3° C (106° to 110° F). Horses, mules, burros, and llamas sweat in the early stages of hyperthermia, but sweating may cease if the animal becomes severely dehydrated. Sweating is evident in horses but imperceptible in llamas, because most sweating in llamas occurs on the ventral abdomen in what is known as the thermal window, where the fibers are less dense and the fiber length is short.

Dogs cool themselves by evaporation of respiratory fluids while panting. The mouth is held open, and the tongue lolls from the mouth. The respiratory rate increases from a normal of 30 breaths/min to 200 to 400 breaths/min. Moisture may be observed dripping from the tongue. As dehydration intensifies, salivation and dripping may slow or cease. Dogs that are unable to effectively pant because of an injury or anatomic conformation are at particular risk for this disorder. Special care needs to be taken when bringing brachycephalic (short-nosed) breeds, such as English Bulldogs or pugs, into the wilderness because these dogs all have a significant degree of respiratory compromise.

Hyperthermia causes a shift of blood volume from the viscera and muscles to the skin, resulting in hypovolemia and varying degrees of hypotension. Hypotension causes hypoxemia of the brain, resulting in dullness, restlessness, and incoordination. Hypoxemia may lead to convulsions and collapse. The shift of blood from the gastrointestinal tract may cause decreased motility and the potential for ileus and tympany. Signs of colic in horses and llamas (kicking at the belly, looking back at the side, treading, attempting to lie down and roll) may be noted.

A 1° C (1.8° F) rise in body temperature requires 10% more oxygen for proper function of the energy systems of the body. When body temperature reaches 41° C (105.8° F), the respiratory system is no longer able to supply sufficient oxygen by normal respiration. Respiratory acidosis and electrolyte imbalances associated with sweating may produce a syndrome similar to septicemia.

Hyperthermia may affect most of the organ systems of the body. The severity of the syndrome cannot be assessed in the field. It is important to recognize the conditions that lead to hyperthermia, to watch for early signs of heat stress, and to stop any activity that contributes to the problem. Mules and burros are not likely to become severely affected because they refuse to go on if stressed. Horses may be driven past their endurance and die of thermal stress. As mentioned previously, dogs that cannot pant effectively (particularly the brachycephalic breeds like bulldogs) can develop heat stress easily.

Treatment

Cessation of excessive muscular activity may be all that is necessary if hyperthermia is mild. If streams or lakes are nearby, the animal can be walked into the water and water can be splashed on its underbelly. Contingencies for hyperthermia are parts of all plans for capture operations for wildlife translocation and reintroduction projects. Water is carried for cooling, along with intravenous fluids to deal with heat stress. Cold-water enemas are the most effective and rapid way to cool the body of a large animal. Caution should be used when cooling a dog. The dog should be cooled to a rectal temperature of 39.4° C (103° F) within 30 to 60 minutes. Overcooling or cooling too rapidly can lead to fatal complications.

External Parasites

The order Diptera, class Insecta includes thousands of species that are annoying or parasitic to humans and domestic and wild animals (see Chapter 47). Trek animals suffer in much the same way as do their human companions. Certain destinations are notorious for insect swarms (flies in Australia, mosquitos and gnats in the Arctic summer). Dipterans are also important disseminators of infectious microorganisms. It is sometimes difficult to differentiate venomous from parasitic species. The saliva of hematogenous dipterans may contain a toxin that aids in altering the endothelium of capillaries to induce free flow of blood, which is then ingested by the fly. Many humans are extremely sensitive to bites from certain flies, and some are sensitive to the toxins in the saliva.

Animals may also be sensitive to the toxins in the saliva. Even nonbiting species, such as the housefly (Musca domestica) or the face fly (Musca autumnalis), if feeding on lacrimal secretions or open wounds, may produce a local reaction causing blepharitis, conjunctivitis, and keratitis. Biting flies (mosquitos, gnats, and midges) may produce local reactions in animals. An attack by immense numbers of simulid gnats may cause debility and even death in animals. In the Mississippi River Valley, horses and mules were killed by massive attacks of the buffalo gnat (Cnephia pecuarium). Swarms of biting insects may cause alarming behavioral responses in horses, including crowding together, head shaking, tail switching, and running. As a youngster, the author was mowing alfalfa hay using a team of horses. A cloud of simulid gnats descended on them. It was difficult to control the horses from bolting and at the same time protect oneself from the biting insects.⁹