Emergency Veterinary Medicine

Published on 14/03/2015 by admin

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Last modified 22/04/2025

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Emergency Veterinary Medicine

Wild animals may stalk support animals. Wild (and occasionally domestic) animals are most likely to respond adversely if:

1. Approached too closely

2. Handled improperly

3. They are fearful for their lives

4. Their young are approached too closely

5. They are cornered or otherwise threatened

6. They are protecting their territory

7. They are breeding

8. They are wounded or ill (diseased)

9. They are being fed by hand

Pretrip Animal Health Considerations

Carry proper health certificates of travel. Perform a proper pretrip examination. Condition and train animals for the expected environment and terrain. Do not travel with immature animals. Dogs should be at least 1 year old. Llamas and horses should be older than 3 years. Well-conditioned and trained horses, mules, burros, and dogs can carry approximately 30% of their body weight. Llamas usually carry only 25% of their body weight.

The normal vital statistics of trek animals are itemized in Table 63-1.

Table 63-1

Vital Statistics of Trek Animals

Horses, Mules, and Donkeys

A tetanus booster should have been given within the past year. Vaccinate against rabies if appropriate. Encephalomyelitis vaccine should be used in endemic areas. Determine internal parasite levels by fecal flotation, and use medication if needed to reduce the parasite burden. Feet should be trimmed and shod properly at least 2 weeks and not more than 4 weeks before a trek begins. Use sole pads if sharp, rocky terrain is expected.

Llamas

Tetanus immunization should be current within the past 6 months. Other basic immunizations should include Clostridium perfringens toxoid, types C and D, within the past 6 months, and vaccinations against leptospirosis and rabies if entering an endemic area. Toenails should have been trimmed within the past 2 months. Ova levels should be checked, but usually treatment with an antihelmintic (ivermectin 0.2 mg/kg subcutaneously, or fenbendazole 5 mg/kg orally) is desirable within the previous 2 months.

Dogs

Immunize dogs against canine distemper, canine adenovirus, leptospirosis, and rabies. Check for internal parasites and fleas. Bathe with a pyrethrin insecticide–containing shampoo, and carry a flea-tick-lice powder. Dogs should be on a heartworm preventive medication if traveling in a mosquito-endemic area. Because external parasites, particularly ticks, can be carriers of multiple diseases, a flea and tick preventive (e.g., Frontline Plus with fipronil) is also highly recommended and can be purchased from a veterinarian before the trip.

Emergency Restraint

Know how to create a halter tie (Fig. 63-1) and a temporary rope halter (Fig. 63-2).

FIGURE 63-1 Sequence of steps to create a halter tie.

FIGURE 63-2 Temporary rope halters.

For horses, mules, and burros, if the animal is down and entangled in rope, wire, or bushes, approach it from its back and keep the head held down until it can be extricated. Stay out of reach of the fore and hind limbs. If the animal is standing, stand close to the left shoulder. If examining the feet and legs of a standing animal, keep your head above the lower body line to avoid having the animal reach forward and strike with a rear limb. You can “ear” the animal by grasping one or both ears. 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 top of the neck. Slide the hand up the neck until the thumb and fingers surround the base of the ear. Squeeze tightly, but do not twist the ear. Be prepared to move with the horse while maintaining a firm grip.

For llamas, one or two people should stand on the side opposite any limb to be lifted, or the animal should be placed next to a tree or large rock to prevent it from moving away. The limb should be firmly grasped. 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 should be suspected. Llamas can be “eared” in a manner similar to that used for horses. Control spitting by draping a cloth over the animal’s nose and tucking the top around the nose piece of the halter.

For dogs, if a mild painful medical procedure 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. 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. The ends of the loop should be wrapped around the muzzle, crossed beneath the jaw, and tied behind the ears.

Conditions Common to All Species

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. Therapy for rope burns is similar to that for human burns.

Foot, Hoof, and Nail Problems

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 may be constructed from soft leather (such as the leather used by crafts people to make moccasins) or duct tape.

Hyperthermia (Heat Stress, Heat Exhaustion)

Signs may 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° C to 43.3° C (106° F 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 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 up to 200 to 400 breaths/min. Moisture may be observed dripping from the tongue. As dehydration intensifies, salivation and dripping may slow or cease.

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.

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 splashed on its underbelly. Contingencies for hyperthermia are part of all plans for capture operations for wildlife translocation and reintroduction projects. Water is carried for cooling and IV 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 be fatal.

Tick Paralysis

Signs may not appear for 5 to 7 days following the tick bite. Initially there is paresis of the legs; progressing to unsteady gait; knuckling; ataxia; and, ultimately, flaccid paralysis of the hind limbs. Loss of motor function ascends cranially, causing paralysis of the forelimbs. Pain perception remains. Even with paralysis of the limbs the animal is bright and alert and able to eat and drink if feed is placed within reach. Ultimately, paralysis involves the neck, throat, and face, causing difficulties in chewing, swallowing, and breathing. Respiratory failure is the cause of death.

Diagnosis

The sequence of clinical signs is the only sure method of diagnosis, unless the tick or ticks are found. That may be quite difficult on an animal the size of a horse. Differential diagnoses should include encephalitides, head or spinal trauma, and hyperthermia.

Management

No antidote is available for the toxin. The offending tick or ticks must be removed, which may produce a dramatic response. Look in the lightly haired areas of the axillary space, perineum, and behind the ears if tick paralysis is suspected.

Skunk Odor Removal

In addition to the obvious odor, skunk musk is nauseating to some people and may also cause retching in dogs. If a person or pet is sprayed in the face, the musk is an irritant that causes conjunctivitis, keratitis, lacrimation, temporary impairment of vision, glossitis, slobbering, and foaming at the mouth.

Management of Odor Removal

Quick flushing of the face and eyes with copious quantities of cold water will restore vision and minimize persistent irritation. If conjunctivitis persists, instill contact lens solution or a drop of olive oil into the conjunctival sac.

The objective of odor removal is to wash away the offending oily liquid and neutralize the compound. Simple bathing will not completely eliminate the odor, which is pungent in a remarkably dilute concentration.

One of the most effective oxidizing agents is a dilute solution of household bleach (Clorox); however, this may bleach clothing and hair and is harsh on the skin of people and animals. Skunk musk is alkaline, so mild acidic solutions may be at least partially effective and will reduce the pungency of the odor. Tomato juice, white vinegar, and ammonia in water have been described but may not completely eliminate the odor.

A formula that is mentioned most frequently is a combination of hydrogen peroxide (347 mL, 3%), water (1 cup [237 mL]), baking soda (sodium bicarbonate, cup [60 mL]), and a dish detergent (1 tablespoon [15 mL]). Mix the peroxide with the water, and then add the baking soda and shampoo. Mix and pour into a squirt bottle/sprayer. This solution may be sprayed onto a dog or horse but should not be sprayed directly into the eyes or nose. The solution should be allowed to remain on the coat for 10 minutes, while being worked into the coat with a gloved hand.

Washable clothing should be washed with a strong soap or heavy-duty detergent. In a permanent camp, items that cannot be washed (shoes, leather goods) may be buried in sandy soil for a few days. The soil will adsorb the odorous chemicals.

A number of commercial products are available that have been formulated to completely eliminate the skunk odor:

1. Neutroleum alpha is nontoxic and may be used on clothing and pets..

2. Skunk-Off is nontoxic and nonirritating, even to mucous membranes, and safe to use on pets and clothing.

3. Odormute is available in granular form and easy to transport. It is nontoxic and may be applied to pets and clothing after being dissolved in water.

4. Summer’s Eve douche is an effective product to neutralize skunk spray odor.

All of the products mentioned are for use on pets or fabric and not recommended for use directly on people. The trek physician is the only one qualified to make such a recommendation. However, washing with soap and copious amounts of cold water will wash away considerable musk.

Plant Poisoning

Certain highly toxic plants that grow in wilderness areas of the United States should be recognized as potentially harmful to pack animals (Table 63-2).

Table 63-2

Poisonous Plants That May Affect Horses or Llamas on Trek

CNS, Central nervous system.

^*In most cases of poisoning from ingestion of poisonous plants, no specific antidote exists. Victims are treated symptomatically. The critical factor is to empty the digestive tract of the plant material with cathartics, parasympathomimetic stimulation, and enemas. Activated charcoal, given orally, may be of value.

Lightning Strike

During an electrical storm, animals on the trek should be positioned in the safest environment possible, away from tall trees and exposed hills. Llamas may be encouraged to lie down in a small ravine or a depression or against a rock face, with the head tied close to the ground. A picket line stake may be used for the tie-down. Avoid tying an animal to a tree; however, using a small bush for a tie-down may be a safer alternative. Horses are more difficult to deal with because it is impossible to get them to lie down unless they are specially trained to do so. Get them into a ravine, a depressed area, or near a rock face.

If the strike is witnessed and the heart has stopped beating, chest compression (cardiac massage) may be performed if it is determined that it is safe for a human to be in the open. With the animal in lateral recumbency, pull the forelimb as far cranially as possible and press on the chest wall just caudal to the triceps muscle. Cardiac massage may be required for a number of minutes.

Snakebite

Llamas and, to a lesser extent, young horses are curious animals and may stick their noses out to investigate strange animals in their area. Thus it is not uncommon for an animal to be struck on the nose. Leg bites may occur in any animal.

Clinical Signs

Venom injection results in pronounced swelling in the area of the bite, beginning 1 to 3 hours after the bite. The most serious consequence of being bitten on the nose is swelling that occludes the nostrils, making it virtually impossible for horses and llamas to breathe. Dogs are not obligate nasal breathers, but the effects of a bite may be more severe in them than in the larger animals. A rattlesnake bite on the nose is an emergency.

Management

A 10-cm (3.9-inch) segment of a 1-cm (0.4-inch) diameter flexible plastic tube should be in the first aid kit of the trek. This should be inserted into a nostril before any swelling occurs. The swelling will be in the area of the nostril, and the tube will prevent occlusion of the nostril, providing a passageway for air. It is not possible to insert a tube after the swelling has developed. If swelling has already developed, the only lifesaving procedure is a tracheotomy.

DO NOT attempt to cut the skin and suck out the venom with your mouth. This procedure is not effective.

The only specific treatment for pit viper envenomation is the administration of antivenom. The same product used for humans is used in animals. One to three vials should be administered intravenously once signs of envenomation have appeared.

Choke

“Choke” in animals usually refers to lodging of food or other objects in the esophagus. The signs of choke may be alarming, but an animal will rarely die unless feed is regurgitated and inhaled into the lungs. Choke is most often caused by overly rapid ingestion of pellets and/or grain. Importantly, animals must be accustomed to any supplemental feed to be used on the trek. Ingestion may be slowed by placing rock pebbles in the container used to feed the animal, causing it to separate the rocks from the feed. Metallic or wooden objects will rarely be swallowed. Llamas and horses are too fastidious in their eating habits to consume such objects.

Retching is the principal sign of choke, as the animal attempts to dislodge the mass. Choked animals are able to breathe, but they are obviously in distress. Saliva may flow from the mouth, and the animal may cough up particles of the material (grain or pellets). It may be possible to feel a mass on the left side of the neck if the obstruction occurs in the cervical area. Peristaltic waves may be observed moving up and down the left side of the neck. The mass may lodge anywhere along the course of the esophagus, but generally it lies within the chest and is not visible externally.

Management

Water may be offered, but feed should be withheld until the problem has corrected itself. Palpate along the lower neck to determine if a bulge is present. If so, gently massage it to determine if it can be moved. Sometimes, moderate exercise may cause the object to move toward the stomach. In some cases, passage of a stomach tube and application of gentle pressure may push the mass into the stomach. Medication (acepromazine, 0.05 mg/kg IV, or xylazine, 0.05 to 0.25 mg/kg IV for a llama and 1.1 mg/kg IV for a horse) may be necessary to relax esophageal spasm.

Wound Dressing and Bandaging

The principles of wound dressing are basically the same as for humans, to provide uniform pressure over a variably shaped surface.

The foot requires special consideration. When dressing a foot wound, make certain that the spaces between the digits of dogs or llamas are padded with cotton. The easiest bandage to apply is a Vetrap elastic bandage that conforms to the odd shape. If a severe foot wound occurs while trekking in the backcountry, additional protection may be necessary to allow the animal to continue on the journey. A sheet of pliable leather of the type used to construct moccasins may be a useful addition to the veterinary medical kit. The dressed foot is placed in the center of the sheet, and then the leather is gathered up around the pastern and held in place by duct tape or another bandage, to form a roughly shaped boot.

Cardiopulmonary Resuscitation

Rescue Breathing

The procedure is different than that employed in humans because mouth-to-mouth breathing cannot be performed on an adult llama or horse. Mouth-to-mouth breathing could be performed on a dog by clamping the mouth and lips shut and breathing through the nostrils. A llama or horse should be placed in lateral recumbency, preferably on the right side. Stand at the animal’s withers (top of the shoulder) and reach across the body to grasp and lift the arch of the rib cage. This maneuver will flatten the diaphragm and expand the chest, producing inspiration. Do not press in this same area to force expiration because this will put pressure on the stomach and possibly cause regurgitation. Instead, press over the heart area just above the elbow and caudal to the muscles of the upper limb. The rate for the horse or llama is 10 to 15 breaths per minute. Rescue breathing in the dog is performed by compressing the chest at the widest segment of the thorax at a rate of 20 to 30 breaths/min.

Cardiac massage may be performed by placing the llama or horse on its right side, if not already there. Have an assistant pull the upper foreleg forward and press the chest in the area vacated by pulling the leg forward. Kneel next to the bottom of the chest. Position the heels of both hands against the chest approximately 6 inches (15.2 cm) above the sternum, with the fingers directed toward the spine. Press firmly with the arms held straight and release quickly. Repeat the movement every second. After 15 compressions, check for a pulse in the saphenous artery on the medial aspect of the stifle in a llama, or listen for the heartbeat with a stethoscope. After 15 heart compressions, administer five cycles of rescue breathing, as described previously. It is futile to continue cardiac massage if no oxygen is available to the heart or the general circulation. Massage must be continued until heartbeat returns and the animal begins to breathe, or when signs indicate that the animal is dead (pupils dilated, no response to touching the cornea).

For a dog, cardiac massage is performed in lateral recumbency in the type of dogs that are likely to be on a trek (small dogs or those that are round-chested are placed on their back and compression exerted over the sternum).

West Nile Viral Encephalitis

Transmission is via mosquito bites (Culex, Aedes, Anopheles species) and possibly other blood-sucking insects. West Nile viral disease has recently become endemic in the United States.

Signs in Horses, Llamas, and Humans

The incubation period is 6 to 10 days. Although most infections are subclinical in horses and humans, 10% of affected individuals develop fever and the encephalitic signs of depression, ataxia, and paresis, particularly of the hind limbs. More advanced signs include head shaking, incessant chewing, paralysis of the lower lip or tongue, severe ataxia, ascending paralysis, and terminal recumbency.

Management

Two vaccines are approved for use in horses in the United States but have also been used in camelids (West Nile-Innovator killed, and Recombitek live). If a trek is planned for an area where West Nile virus is endemic and when mosquitoes are prevalent, trek horses and llamas should be vaccinated (two injections 1 month apart).

Unique Disorders of Horses, Mules, and Donkeys

Laminitis (Founder)

Clinical Signs

Laminitis usually develops on both fore feet, but rear feet may also be affected in severe cases. The horse shifts its center of gravity to the hind limbs to minimize pressure on the fore feet, standing with the hind limbs forward under the body and the fore limbs extended in front of the body (Fig. 63-3). The feet are warm or hot to palpation, and there is a pounding digital artery pulse. The horse is reluctant to move.

FIGURE 63-3 Stance of a horse with laminitis. Front and hind legs are extended forward.

Management

Prevention or minimizing the effects of the inciting causes of laminitis is vitally important. Once clinical signs occur, the objectives of treatment are to eliminate the predisposing factors, decrease inflammation, and maintain or reestablish blood flow to the laminae.

If laminitis is the result of a digestive upset, it is imperative to administer a cathartic (magnesium sulfate [Epsom salts], 1 kg in 4 L of water via nasogastric tube). Phenylbutazone, 6 mg/kg IV daily, should be administered to relieve pain so that the horse will move. Acepromazine maleate, 0.04 mg/kg IM every 6 hours, is used as a vasodilator to enhance blood flow to the laminae. In acute laminitis, the feet are warm or hot, so the inclination would be to soak the feet in cold water. This is contraindicated because the goal is to increase circulation to the foot.

Mild exercise is an important aid in preventing damage to the laminae. The horse should be exercised slowly on soft ground for 10 to 15 minutes every hour for 12 to 24 hours, and then exercise should be stopped. Even slow walking may be quite painful. A low volar nerve block relieves pain and inhibits vascular constriction within the foot. This is accomplished by palpating the pulsating artery on the posterior lateral aspect of the fetlock (Fig. 63-4). The nerve lies posterior to the artery. With a 20- to 22-gauge needle, 3 mL of 2% lidocaine is injected over each nerve. It may be necessary to repeat nerve blocks two or three times daily for several days. Corticosteroids are contraindicated.

FIGURE 63-4 Diagram of the anatomy of the equine fetlock. A, Skin. B, Flexor tendons. C, Volar nerve. D, Palmar digital artery. E, Digital vein. F, Suspensory ligament. G, Sesamoid bone. H, Metacarpal bone (cannon).

Saddle, Cinch, and Rigging Sores

If the lesion is rested and treated as inflamed tissue, complete healing may occur. However, if the saddle is reapplied, it overlies a lump that is subject to abrasion. The injury can extend through the dermis, resulting in severe ulceration. Cinch and rigging sores are usually caused by friction, leading to blister formation.

Clinical Signs

Hot and tender swellings are the primary signs of acute saddle sores. The hair or epidermis may be rubbed off. General sensitivity over the back is usually caused by muscle soreness.

Treatment

Prevention is better than treatment. Proper pads or blankets must be selected for each horse.

Upon arrival at a rest area, the girth should be slowly loosened at intervals of 10 to 15 minutes to prevent rapid flow of blood into ischemic areas.

Once a sore has developed, the horse must be rested or the tack changed to eliminate pressure or friction on the lesion. Holes are often cut in pads to accommodate a saddle sore, but spot pressure at the ring edge may be as detrimental as the original cause of the saddle sore. Keep tack cleaned and in good repair. When the saddle is removed, cold water poured over the back for 15 minutes may minimize swelling.

Myopathy

Exertional myopathies of horses vary from simple muscle soreness, through the “tying up” syndrome (similar to charley horses in humans), to paralytic myoglobinuria (rhabdomyolysis, azoturia).

Clinical Signs

Mild muscle soreness is characterized by alterations in gait that indicate muscle weakness. As severity increases, the gait becomes progressively altered until the horse is in obvious pain and reluctant to move. The horse has an anxious expression and may sweat excessively. Affected muscles are painful to palpation and may be swollen. Skin temperature over the muscle may be elevated. Myoglobinuria may be observed in moderate to severe cases and should prompt resting or treating the horse.

Treatment

Rest is paramount in all cases. A rider may have difficulty differentiating the pain associated with myopathy from that seen with colic until the horse is allowed to lie down, look at its side, or kick at its belly). It is disastrous to force the severely myopathic horse to walk, as is done with a suspected case of colic. If there is doubt, the horse should not be exercised.

Horses in inaccessible locations should not be walked out until all possible recovery has taken place. Horses with mild muscle soreness may improve if walked slowly, but rest from ride exertion is the primary recommended therapy.

Dehydration

The horse must have an adequate amount (37.9 to 56.8 L [10 to 15 gallons]) of water each day during a trek.

Clinical Signs

Signs of mild dehydration are low urine output, dry mouth, and mild loss of skin elasticity. More severe dehydration is characterized by marked loss of skin elasticity. The eyes become sunken. Weakness, fever, and weak pulse may be observed. Sweating is not possible, even with elevated body temperature. Shock ensues if left untreated.

Treatment

During 3 hours of hard work, a 450-kg (992.1-lb) horse may lose as much as 45 L (11.9 gallons) of fluid. The horse should be allowed to drink along the trail if water is available. Small amounts of cool, but not cold, water should be offered. If the horse refuses to drink, gastric intubation may be indicated. Fluid is also absorbed from the colon; thus enemas (10 to 20 L [2.6 to 5.3 gallons] of water) are effective in rehydration. Electrolyte replacement is encouraged, but for the usual case of dehydration, it is not critical. Packaged electrolytes are available in veterinary supplies shops.

Heat stress usually accompanies dehydration, so cooling (such as shade or a water bath) is important. Administration of IV fluids, if available, is routine therapy.

Camels are uniquely adapted to desert conditions. They are able to survive a week without water. Optimally a camel should be watered daily, just as are horses and llamas. Camels do not store water but conserve it by enduring a diurnal fluctuation of body temperature, from a normal 37.0° C (98.6° F) up to 42° C (107.6° F). The body acts as a heat sink during the heat of the day, thus conserving vital water that would otherwise be lost through evaporative cooling. During the cool desert night, the heat is dissipated by conduction. Camels are able to concentrate urine to a syrup consistency to avoid water loss through urine. Fecal pellets are passed that are dry enough to be used for fuel immediately following defecation.

Exhausted Horse Syndrome

The term exhausted horse syndrome (EHS) was coined to describe a complex metabolic disease occurring when horses are pushed beyond endurance limits.

Clinical Signs

1. Movements are lethargic, head held low.

2. Facial grimacing and corneal glazing are present.

3. Anorexia is typical, and frequently the horse has no inclination to drink, even though dehydrated.

4. Heart rate, respirations and temperature are elevated. (Heart rates of 150 beats/min are not uncommon after a grueling climb. With 10 to 15 minutes of rest, the heart rate of a conditioned horse should drop below 60 beats/min, whereas in the exhausted horse, tachycardia and tachypnea persist.) Auscultation of the thorax may reveal moist rales and, in extreme cases, frank pulmonary edema.

5. Severe dehydration is the most consistent sign of EHS. (See signs described in Dehydration.)

6. Horses suffering from EHS are prone to colic, which also may occur independently. (See later.)

Treatment

Rest, rehydration, and electrolyte supplementation are the keys to recovery.

Synchronous Diaphragmatic Flutter

Synchronous diaphragmatic flutter (SDF) is a clinical sign observed in endurance horses while on long-distance rides and may be seen on an expedition. SDF is defined as a spasmodic contraction of the diaphragm synchronous with the heartbeat. It is not life threatening in itself but indicates mild to serious metabolic conditions that may be or become life threatening. Overexertion with excessive sweating produces metabolic alterations. The development of SDF at any point on a trek should be ample reason to prevent the horse from going farther until the metabolic alteration is resolved.

Clinical Signs

SDF may develop after 32. 2 to 48.3 km (20 to 30 miles) of riding. The primary sign is spasmodic contraction in the flank area. The “thump” is easily felt by light palpation in the flank area. A person who auscultates the heart while holding a hand over the dorsocaudal rib area can tell that diaphragmatic contraction is synchronous with the heartbeat. SDF may be the only clinical sign noted, or it may be seen as part of EHS.

Treatment

Rest and rehydration are required.

Colic

Colic is the clinical manifestation of abdominal pain, usually the result of a gastrointestinal disorder. The most likely inciting causes on a trek are overeating of nonregular forages, ingestion of poisonous plants, or exhaustion.

Clinical Signs

Horses express colic by looking back at one side, stamping the feet, getting up and down, rolling, and pressing the head against trees or rocks. The pulse rate may exceed 100 beats/min with severe pain. The conjunctival membranes are congested and cyanotic.

Treatment

1. Mild obstructions may be relieved by hydration and administration of a cathartic.

2. Cold water enemas may stimulate sluggish intestinal peristalsis and relieve impaction of the small (terminal) colon.

3. For pain and spasms, give flunixin meglumine, 0.6 mg/kg IM bid.

4. Walk the horse to prevent it from lying down and rolling, which may result in torsion of the intestine.

Unique Problems of Dogs

Laryngeal Paralysis

This disease occurs in older medium- and large-breed dogs, particularly Labrador retrievers. The problem occurs because of degeneration of the recurrent laryngeal nerve that innervates the intrinsic muscles of the larynx.

Clinical Signs

1. Respiratory stridor

3. Inability to thermoregulate effectively by panting. Because they cannot dissipate heat, heat stroke can result.

Treatment

Prevent and manage heat and exertional stress by keeping the dog cool and calm. If the dog is in extremis, endotracheal intubation or tracheostomy can be performed in addition to active cooling.

Gastric Dilatation and Volvulus (“Bloat”)

Gastric dilatation and volvulus occurs most commonly in older, large- and giant-breed dogs, particularly deep-chest breeds such as Great Danes. The stomach twists such that both the esophagus and pyloric outflow become occluded. The stomach distends with gas and stretches until it severely impedes blood flow with resultant shock and gastric necrosis. This condition can be fatal within 6 hours of onset if untreated, and mortality rates are high even with appropriate treatment.

Clinical Signs

1. Inability to swallow or to vomit; attempts to vomit produce only saliva

2. Progressive distention of the abdomen

Treatment

1. Arrange emergent evacuation for definitive surgical treatment.

2. Place an orogastric tube to decompress the stomach, or if unable, decompress the stomach with a large bore IV catheter. This procedure should only be attempted in situations where veterinary care is not immediately available, because of risk for lacerating abdominal organs. The catheter is inserted about a hands’ width behind the last rib in the center of the lateral body wall. The operator will hear and smell gas escaping if the procedure is successful. This can repeated multiple times if necessary while the animal is being transported.

Porcupine Quills

When dogs are brought into porcupine country, the risk for an encounter is great. Some dogs fail to learn from experience and are repeatedly quilled. The dog must have physical contact with the porcupine for the tail to introduce the quills. The muzzle and face are the usual sites of penetration, and a dog can be blinded by perforation of the eye.

The quills should be extracted, ideally with a pair of pliers, because retrograde barbs on the quill foster migration and abscess formation.

The process is painful, and sedation with diazepam, 0.2 to 1 mg/kg IM or IV, is indicated.

Grass Awns

Numerous species of grass awns (“foxtails”) may become attached to the dog’s hair coat or lodged in the external ear canal, nasal passage, conjunctival sac, or interdigital space.

Signs depend on the location of the foreign body. When it is within the ear canal, the dog paws at its ear and shakes its head. The head may be held tilted. Exudate may flow from the ear. Awns in the nostril cause sneezing and nasal exudate. Awns in the conjunctival sac cause lacrimation, photophobia, and corneal edema and ulceration. The dog paws at the eye. Awn penetration between the digits and at other locations through the skin is more difficult to diagnose because the awn may be at some distance from the fistula.

Awns must be removed physically. Sedation, topical anesthesia, or both may be necessary. Although topical ophthalmic anesthetics are desirable in the eye, lidocaine may be used in an emergency. A pair of small alligator forceps is most suitable for reaching into otherwise inaccessible places. An otoscope may be necessary to visualize awns in the nostril or ear canal. Instillation of an antiseptic or antibiotic ointment is desirable after removal of the awn.

Stinging Nettle Poisoning

Stinging nettle (Urtica species) is common along streams and lakes in wilderness areas. Leaves and stems are covered by harsh hairs, some of which have a tiny ball tip that breaks off just before penetration. The specialized hairs are hollow. A base gland produces histamines and acetylcholine, which are injected into the victim.

Short-haired dogs that move through patches of stinging nettle are at risk for poisoning from the cumulative effect of thousands of minute injections of acetylcholine. Weakness, dyspnea, and muscle tremors are characteristic of the action of acetylcholine on peripheral nerves. Parasympathomimetic effects include salivation, diarrhea, tachycardia, and pupillary dilation. Atropine sulfate, 0.04 mg/kg subcutaneously, is a specific treatment.

Medication Procedures

A list of medications and indications for their use is provided in Table 63-3. In the horse, intramuscular injections are given in the neck or rump. Subcutaneous injections are given by lifting a fold of skin just cranial to the scapula. IV injections are given in the jugular vein, which is easily distended along the jugular groove on the ventral aspect of the neck.

Table 63-3

Medications for Trek Animals

IM, Intramuscular; IV, intravenous; PO, oral; q, every; bid, twice a day; tid, 3 times a day; qid, 4 times a day.

In the llama, intramuscular injections are given in the relatively hairless area at the back of the upper rear leg, by standing against the body in front of the rear limb while facing the rear and reaching around the back of the animal to give the injection. Subcutaneous injections are given in the relatively hairless area of the caudal abdomen, just in front of the rear limb or by lifting a fold of skin just cranial to the scapula.

In the dog, intramuscular injections may be administered in the triceps muscles caudal to the shoulder or in the muscle masses on the upper rear limb. Subcutaneous injections are made by lifting a fold of loose skin on the neck near the withers. IV administration is via the jugular vein or the cephalic vein. For the latter, an assistant grasps the limb at the elbow to occlude the vein, which courses on the dorsal aspect of the forearm. The vein is more visible if the hair is wetted down with water.

Euthanasia

Indications for euthanasia include compound and comminuted fractures of long bones; falling or sliding into inaccessible places from which the animal is unable to extricate itself or trek participants are unable to aid the animal; lacerations exposing abdominal or thoracic organs; head injuries resulting in persistent convulsions or coma; and protracted colicky pain unrelieved by analgesics or mild catharsis. The expedition may carry a bottle of euthanasia solution, which must be given intravenously or intraperitoneally. If firearms are carried, a properly placed bullet to the head produces a fast and humane death. For placement the shooter stands in front of the animal’s head and draws an imaginary line from the medial canthus of each eye to the base of the opposite ear. The shot should be aimed where those lines cross and approximately perpendicular to the contour of the forehead (Fig. 63-5). The tip of the barrel should be no more than 6 inches from the head. A heavy blow to the head at the same location is equally effective. The blow may be administered with the blunt edge of a single-bladed ax or hatchet. A large rock held in the hand may also be used. A less desirable but sometimes expedient method is to sever the jugular vein to allow exsanguination. This would be best used on an animal that is already unconscious.

Figure 63-5 Location for euthanasia blow or shot.

Related

Field Guide to Wilderness Medicine