TY - JOUR
AU - Thomas, Todd
AB - Abstract There are about 2,500 war and military service dogs in service, with about 700 serving at any given time overseas. Military Working Dogs (MWDs) are critical assets for military police, special operations units, and others operating in today’s combat environment. The expectation, given the significant combat multiplier impact of these dogs and the intense bond between the handler and dog, is that injured working dogs will receive the same level of care as any injured U.S. military personnel. Veterinary care is available at multiple locations throughout theater, and the veterinary healthcare team is the MWD’s primary provider. Yet, human healthcare providers (HCPs) may be the only medical personnel available to MWDs that are gravely ill or injured. As most HCPs are unfamiliar with medical care of dogs, the Joint Trauma System published a Clinical Practice Guideline (CPG), a set of detailed clinical guidelines for managing life-threatening problems of MWDs encountered in combat operations. The CPG is available at the JTS website. This article is covers the most common urgent MWD care challenges HCPs may face. military working dog, MWD, combat casualty care, dog, canine BACKGROUND About 40–50% of healthcare providers (HCPs) enrolled in the Joint Forces Combat Trauma Management Course over the past 5 years, who had deployed at least once previously, routinely said that they managed emergently injured military working dogs (MWDs). Care provided by HCPs is limited to circumstances in which the dog is too unstable to transport to veterinary facilities or medical evacuation is not possible; immediate care is necessary to preserve life, limb, or eyesight; and veterinary personnel are not available.1 GOAL This article briefly discusses handling of MWDs, and commonly encountered emergent clinical conditions with MWDs, and serves to highlight situations that HCPs may have to manage. HANDLING AND MANAGEMENT OF MWDS The overarching goal when managing injured dogs is return to normal function and duty. HCPs should be reasonable, however, when considering the extent to which resources are allocated, and consider euthanasia if deemed appropriate for catastrophic injuries – dogs with multiple limb amputations or severe brain injury, for example, are not adoptable. MWDs are potentially dangerous when ill, injured, or stressed, and especially when not under the control of a handler. Dog handlers are the best persons to control the MWD. They usually know of any medical problems and they have first aid skills to assist. If the assigned handler is not present, the MWD unit is responsible to provide another handler. A handler must be immediately available 24 hours a day when MWDs are in a facility. MWDs must never be transported without a handler. Never examine a MWD without a handler or knowledgeable person present. NOTE: Avoid treating an injured MWD handler in the presence of an MWD. An MWD may attack HCPs if it feels the handler is threatened (J. Giles, personal communication). MWDs should be muzzled whenever being handled, unless medical issues prevent muzzling. Remove the muzzle when: Not actively handling the dog, if the dog is sedated or anesthetized. If the dog is having breathing difficulty. If the muzzle prevents effective cooling by panting. CARDIOPULMONARY RESUSCITATION HCPs should consider cardiopulmonary resuscitation (CPR) of MWDs in cases of non-traumatic cardiopulmonary arrest (anesthesia-related, hypothermia, near drowning, electrocution). If the tactical situation and resources permit, HCPs may consider CPR in MWDs with cardiopulmonary arrest (CPA) due to blast injury, blunt trauma, or penetrating trauma, although successful resuscitation in these cases is unlikely. Overall, survival with acceptable function is about 5% for dogs.2,3 Figure 1 depicts resuscitation guidelines for dogs. FIGURE 1. Open in new tabDownload slide Clinical algorithm for canine cardiopulmonary resuscitation. Adapted from Fletcher et al., RECOVER.2 Basic life support for dogs follows the American Heart Association guidelines for people. A recent evidence-based review of CPR in dogs, with clinical recommendations, guides canine CPR.2 Initiate two-person, closed-chest CPR if a dog is noted unresponsive or with apneic breathing. Immediately begin sustained, forceful chest compressions with the MWD in lateral recumbency (on either side) at a rate of 100 compressions per minute. Sustain compressions for at least 2–3 minutes per cycle. Hand placement can be directly over the heart (where the elbow crosses the chest above the sternum when the forearm is pulled caudally) or over the widest part of the chest; hand configuration is not critical. Ensure adequate relief of downward pressure during the relaxation phase of the compressions. Establish an airway as rapidly as possible and as soon as possible; however, start chest compressions first! Intubate the MWD or perform an emergent tracheostomy. Ventilate the patient at a rate of 8–10 breaths per minute. Avoid hyperventilation. Oxygen is preferred when ventilating MWDs during CPR, but room air is acceptable if oxygen is not available. Initiate advanced life support as soon as feasible, with ECG monitoring to guide actions. The most common arrest rhythm in dogs is pulseless electrical activity (PEA), followed by asystole, ventricular fibrillation, and sinus bradycardia.2 Seventy percent of dogs that arrest will have PEA, or asystole, as the initial arrest rhythm.2 Epinephrine or vasopressin are best choices for these rhythms or for empiric use if ECG capability is not available. Sinus bradycardia commonly precedes overt arrest, and use of atropine may prevent development of CPA. In the deployed setting, there is no role for transthoracic pacing in MWDs with PEA or asystole. Ventricular fibrillation often develops during resuscitation. Perform external defibrillation if possible and as rapidly as possible if ventricular fibrillation is noted; biphasic defibrillation is ideal.4 Apply paddles to either side of the chest with the MWD in dorsal recumbency, or place a flat paddle under the MWD lying in lateral recumbency and a standard paddle on the upper chest wall. Defibrillate up to three times at each energy level, but perform aggressive chest compressions for at least 2 minutes before attempting each defibrillation. Follow all drugs with at least a 20 mL sterile saline push. Place a central venous catheter when feasible. Intravenous (IV) access is critical; place multiple peripheral or intraosseous (IO) catheters or perform venous cut-downs. Do not give large volumes of fluids to MWDs during CPR, unless severe hypovolemia is thought present; give fluids during CPR to facilitate drug delivery only. Resuscitated dogs will require intensive care. Many dogs arrest again, and most do so in the first 4 hours after resuscitation.5 Successful resuscitation is unlikely if a dog arrests again, so HCPs should balance resources against repeated attempts at resuscitation. Key management issues for MWDs in the post-resuscitation phase are similar to those in people. There is no role for open-chest CPR by HCPs in MWDs; consider euthanasia if a resuscitative thoracostomy is deemed necessary to manage CPR. EMERGENT SURGICAL MANAGEMENT Emergent surgical management of injured MWDs may be necessary by HCPs to afford a chance at patient survival. This should be considered only if the provider has the necessary advanced surgical training and experience; the provider feels there is a reasonable likelihood of success; and the provider has the necessary support staff, facilities, and monitoring capabilities for post-operative care without compromising human patient care. Thus, emergent surgical management is generally restricted to Role 2 or higher facilities and by trained surgical specialists with adequate staff. Direct communication with a U.S. military veterinarian is essential whenever possible before considering surgical management, and during and after surgery, to optimize outcome. NORMAL CLINICAL PARAMETERS, VENOUS ACCESS, MONITORING Most MWDs are German shepherd dogs, Belgian Malinois dogs, or Labrador retriever dogs, and typically weigh 50–80 pounds (23–36 kg). Ideally, dose based on actual body weight. The normal resting heart rate is 50–60 bpm, but these dogs are excited, agitated, or injured, so rates closer to 100 bpm are common. Panting is common, especially when dogs are excited, agitated, stressed, or hyperthermic. The normal rectal temperature range is 101–103° F; skin and aural thermometry using human devices are not accurate. Venous blood collection and catheterization sites for routine blood sample, drug administration, and routine IV fluid administration are the cephalic vein on the forearm or the lateral saphenous vein on the hind leg. The external jugular vein can be used for large volume fluid delivery, central IV catheterization, or repeated blood sampling. The arterial pulse is best palpated at the proximal medial femoral artery or the dorsal pedal artery crossing the dorsal aspect of the hind paw. Heart sounds are best heard over the left lower lateral thoracic wall at the fourth to sixth intercostal space, about where the elbow crosses the sternum when the fore leg is pulled caudally. Arterial blood pressure is measured using oscillometric non-invasive techniques, with cuffs placed over the dorsal pedal artery or lower forearm; use pediatric (size 4–5) or neonatal (size 6–8) human cuffs for accurate results. Human pulse oximetry finger probes are reliable when placed on the dog’s tongue; thus, pulse oximetry can only be safely used in unconscious, sedated, or anesthetized dogs. Apply ECG adhesive electrodes to the foot pads of both fore limbs and the left hind limb, and tape in place. Canine rhythms and intervals are similar to people. Canine blood can be analyzed on instruments designed for human blood. Laboratory test results and reference ranges are similar for dogs and people. Results are reliable except for total calcium and albumin; use caution when interpreting results for these analytes. PROVIDE ANALGESIA AND ANESTHESIA One of the first things required with injured MWDs is to calm them, sedate them, or perform general anesthesia. MWDs often require heavy sedation for simple procedures like wound management or splint application. Tailored protocols are provided, based on the level of sedation or anesthesia required MWD handlers or combat medics may have given morphine, fentanyl or ketamine before transport, which may affect assessment of the MWD’s mentation; inquire about drug use before presentation. All drug combinations for the protocols are given by the intramuscular route, and are selected based on availability in theater. If used within 5 minutes, all drugs can be mixed in the same syringe without complications. Wait at least 20 minutes after administration to allow maximal effect; starting too soon after administration will result in less than optimal results. Dosages for many analgesics in dogs are significantly higher than for people. For example, the common dose for morphine is 1 mg/kg body weight, and for tramadol is 5–10 mg/kg body weight. Inadequate dosing is ineffective and may lead to “wind up” that complicates care. Dose as recommended, or consult with a veterinarian before changing doses. It is optimal to place an IV catheter once feasible for emergency drug and fluid delivery. Protocols include opioids, which typically cause vomiting in dogs, often within 5 minutes of administration; handlers should be prepared to remove muzzles if vomiting is anticipated, to reduce chances of aspiration. Use the mild sedation protocol to relax dogs for examination, handling, transport, or short minor procedures that will not cause pain. This protocol uses a combination of midazolam and either hydromorphone or morphine, and results in a calm but reactive dog that is noise sensitive. Use the deep sedation protocol for dogs that are fractious, need a procedure that may cause mild discomfort, or for procedures less than 30 minutes in duration (e.g., radiography, wound care, bandaging). This protocol uses a combination of midazolam, either hydromorphone or morphine, and ketamine. This protocol will result in a very sedate but rousable dog. If needed, an IV catheter can be placed once the dog is sedate, and propofol in incremental small IV boluses can be used to supplement sedation or allow induction of general anesthesia. General anesthesia is indicated for any dog requiring surgery or other painful procedures, advanced imaging, or prolonged wound care or bandaging. Premedicate using the deep sedation protocol. Place an IV catheter and induce with propofol to allow endotracheal intubation with a size 9–11 cuffed endotracheal tube. Maintain general anesthesia with isoflurane or sevoflurane in oxygen, titrated to effect. Use hydromorphone, morphine, or fentanyl for additional intraoperative analgesia. Scheduled analgesia is best since dogs often hide or fail to show pain. Intermittent IV or intramuscular analgesia options, and continuous rate infusion and oral analgesia protocols are provided. The key is not to wait for dogs to show signs of pain, nor to assume a quiet dog curled up in the corner of its carrier is a pain-free dog. HEMORRHAGIC SHOCK The majority of dogs managed for shock by HCPs have trauma-induced hemorrhagic shock. Treatment by handlers and combat medics has typically been performed, with varying degrees of success.6 Expect dogs to arrive with pressure dressings, hemostatic gauze packed into wounds, and improvised tourniquets. Expect inadequately controlled bleeding, and suspect “hidden” hemorrhage in the chest and abdomen.5,7 When managing severe limb injuries and traumatic amputations, note that dogs have excellent collateral circulation, and major vessels can be ligated without long-term adverse consequences.5 Use TFAST and AFAST to rapidly screen for intracavitary hemorrhage;8,9 assume any intracavity fluid in a traumatized dog is due to bleeding until proven otherwise. Shock management in dogs is similar to that in people. A shock resuscitation algorithm is provided (Fig. 2). Provide immediate fluid therapy targeted to specific endpoints, provide supplemental oxygen, and identify and treat the underlying cause.10–16 Use multiple large-bore IV or IO catheters or venous cut-downs. IO catheters are reliably placed on the lateral proximal humerus or the medial proximal tibia. Crystalloid fluid challenges, as needed based on response to therapy, are better than large volume fluid administration.14–16 For simplicity, the algorithm includes predetermined bolus volumes based on body weight; reassessment over time is critical to avoid volume overload while sufficiently correcting deficits. In most cases, MWDs in shock can be successfully stabilized with 2–3 bolus challenges. FIGURE 2. Open in new tabDownload slide Shock resuscitation protocol for MWDs. Synthetic colloids and hypertonic saline (HTS) can be used in dogs with refractory shock. While very limited data suggest increased risks, dogs do not seem to develop complications seen in people, so HCPs should be aggressive with colloid use in dogs with refractory shock – the benefits are deemed to outweigh the risks in these cases.17–19 Hydroxyethyl starch can be used as a bolus.14–16,19,21,22 HTS can be used as a small volume resuscitation bolus, using 7.0–7.5% HTS.14–16,21 Synthetic colloids and HTS should be used in conjunction with crystalloid fluid therapy. Do not use human serum albumin in dogs; although some reports suggest benefit in a very specific subset of canine patients with severe hypoalbuminemia,23,24 immediate and delayed life-threatening complications are reported, and the risks outweigh the benefits in the management of shock.16 Canine blood products are not available in a timely manner for emergent HCP use.6 Dogs cannot be transfused with human blood. HCPs will have to manage hemorrhagic shock with crystalloid and colloid therapy. There is limited, but promising, data to guide use of tranexamic acid in dogs.12,25–27 Epsilon aminocaproic acid has also been evaluated in small numbers of dogs with traumatic hemorrhage,25,28 with promising results. Doses and guidelines for use of tranexamic acid and epsilon aminocaproic acid in dogs with refractory hemorrhagic shock, limb amputation, penetrating torso trauma, and ongoing severe bleeding are provided. HEAT INJURY Heat injury is the leading non-trauma cause of death in deployed MWDs (K. Mann, personal communication). Well-acclimated dogs working in hot, humid environments routinely have core body temperatures of 105°±1° F.29,30 However, with cessation of work and access to shade and water, dogs that do not develop heat injury rapidly cool to normal body temperature (101–103° F). Since dogs do not sweat significantly, panting is the most critical method for cooling, to expose the highly vascular tongue for evaporative cooling. There is no cut-off temperature that denotes heat injury; temperatures as low as 106° F have been associated with pathology. However, dogs with moderate to severe heat injury usually have sustained rectal temperatures of 107° F or higher.31–33 Most dogs develop heat injury due to heavy exertion in hot, humid environments, especially if inadequately acclimated. Rarely, dogs are treated for heat injury secondary to partial airway obstruction or inadvertent enclosure in vehicles. Heat injury in dogs is described as mild (“heat stress”), moderate (“heat exhaustion”), and severe (“heat stroke”).31,32,34,35 MWD handlers are trained to recognize and treat heat injury in the field; thus, dogs may be hypothermic on arrival if treated before presentation. Dogs with moderate to severe heat injury frequently develop multi-organ complications and have a high case fatality rate.32,34,35 Poorly managed or untreated, heat injury is a progressive process. This progression is well described.31,32,34,35 Dogs with moderate heat injury become weak, distressed, and pant uncontrollably. Distinguishing between controlled versus uncontrolled panting is a reliable means of crudely assessing severity of heat injury. Controlled panting means the dog retains some voluntary control over its breathing and will temporarily stop panting if exposed to a noxious stimulus (such as an alcohol-soaked cotton ball). A dog with uncontrolled panting will not stop breathing even in the face of noxious stimuli, because inherent survival mechanisms drive panting continuously. Some overheated dogs display petechiae or ecchymosis (best noted on the ear pinna, mucous membranes of the mouth, and skin over the abdomen), and vomiting or diarrhea. Dogs with severe heat injury show all of the signs of moderate heat injury, but demonstrate some degree of central nervous system involvement, collapse, and shock. Common central nervous system signs are ataxia, blindness, seizures, and stupor or coma. Dehydration frequently accompanies heat injury. The fundamental treatment for moderate to severe heat injury is to cool the dog as rapidly as possible – without causing other problems – until the rectal temperature is 105° F or lower. The best ways to emergently cool MWDs are to soak the dog to the skin with room temperature water, give room temperature IV fluids, and direct fans on the dog. Do not use cold or iced IV fluids, ice water immersion, ice water enemas, peritoneal lavage, or surface cooling with ice packs or alcohol, as these methods cause peripheral vasoconstriction and shivering that actually may increase core temperature, and dogs appear very prone to rebound hypothermia that can be extremely difficult to correct.31,32 Reduce the rate of cooling when the rectal temperature reaches 105° F; cease cooling efforts and dry the dog when the temperature reaches 103° F to prevent rebound hypothermia. Provide passive warming if the rectal temperature is less than 100° F. Monitor and manage common complications of heat injury, to include hypotension, glucose and electrolyte abnormalities, coagulopathy and thrombocytopenia, cardiac arrhythmias, and gastroenteritis. UPPER AIRWAY OBSTRUCTION While upper airway obstruction is an uncommon problem in deployed MWDs, immediate action is required. The most common causes of obstruction are laryngeal paralysis, “rewards” used by the handler (balls), and facial trauma. Dogs with upper airway obstruction present with severe respiratory distress with labored inspiration and abnormal upper airway noise (e.g., stertor, stridor). Dogs may be conscious but extremely agitated; extreme care is necessary to protect HCPs. Provide immediate oxygen therapy; however, because of the danger of working with an agitated dog, face mask or “blow by” oxygen supplementation, in which the end of the oxygen tubing from the source is held as close to the face as possible at high oxygen flow rates, may be all that is possible. These methods are not ideal, but do provide inspired oxygen concentrations from 40–70%36 until the airway is secured. Rapid sedation or general anesthesia is likely necessary for definitive management. If the obstruction can be removed, oral intubation is ideal. If the obstruction cannot be removed, emergent tracheostomy is indicated. Endotracheal Intubation Endotracheal intubation in the dog is relatively easy, compared to human intubation. If necessary, sedate and induce with propofol as previously described. Position the dog on its chest, and have the handler lift and hold the upper jaw just behind the upper canine teeth. Gently but completely pull the tongue forward and down, depressing the lower jaw to open the mouth as fully as possible. Most adult human laryngoscopes are adequate to visualize the larynx and gently depress the tissues just cranioventral to the epiglottis to open the laryngeal orifice. Most MWDs will need a size 9–11 mm endotracheal tube, preferably cuffed. Once placed, secure the tube using gauze tied around the tube and then tied around the upper jaw. Mechanical ventilation guidance is provided. Emergent Tracheostomy Perform emergent tracheostomy if airway access cannot be obtained by orotracheal intubation. In unconscious, sedated, or anesthetized dogs, position the animal in dorsal recumbency and extend the neck and place a rolled towel or sandbag under the neck to force the trachea upwards. In conscious MWDs that demand immediate action, sedate the dog, position the MWD in sternal recumbency, locally anesthetize the surgery site, and extend the head upward to expose the ventral neck. Clip the hair over the center of the ventral neck from the larynx to approximately the center of the neck, and quickly prepare the skin with surgical disinfectant. Make a full-thickness, ventral midline skin incision 2–3 finger widths below the larynx, ideally over the third to fifth cartilage rings, parallel with the long axis of the trachea. Transverse skin incisions (perpendicular to the long axis of the trachea) increase the risk of injury to adjacent vessels and nerves. Separate the muscle bellies overlying the trachea using sharp and blunt dissection. Place a small retractor to spread the muscle bellies and allow visualization of the trachea. Make a transverse incision completely through the annular ligament between the third and fourth or fourth and fifth tracheal cartilages to create the tracheostomy. — Do not extend the incision more than half the diameter of the trachea. — Do not incise at the cricothyroid ligament. Using a cricothyroidotomy hook or stay sutures, retract the lower tracheal ring to open the tracheal lumen. Insert a tracheostomy tube (ideal) or endotracheal tube, using the largest tube that will fit in the trachea; 9–11 mm tubes are typical. Once the tube is inserted, place long stay sutures around the cartilage rings above and below the tracheostomy. These allow rapid control of the airway should the tube become dislodged or occluded, and facilitate tube maintenance. Secure the tracheostomy tube to the patient using umbilical tape or roll gauze, tied to the wings of the tube and passed around the neck, and tied with a quick-release knot. Do not suture the tube to the skin, as rapid removal is not possible if it obstructs. Insert the inner cannula (if provided) in the tracheostomy tube and inflate the cuff of the tracheostomy tube. GASTRIC DILATATION-VOLVULUS SYNDROME Gastric dilatation-volvulus syndrome (GDV), commonly called “bloat” by handlers, is a multifactorial, rapidly progressive, life-threatening surgical emergency, common in large breed dogs.37 Under certain circumstances, the stomach will rapidly dilate with ingested air, food, and water. This dilatation predisposes to development of a volvulus, with the stomach “flipping” on its long axis. Fermentation of food, retention of gastric secretions, and influx of fluid exacerbates the dilatation. Given the volvulus, there is no way to empty the stomach. The dilatation can progress to life-threatening shock in less than 4 hours. The dilated stomach prevents venous return from the abdomen and hind limbs, ultimately leading to decreased cardiac output.37 Figure 3 is a lateral abdominal radiograph of a dog with severe gastric dilatation that demonstrates the extent of dilatation possible. Death in the long-term period is due to the myriad complications of this extreme form of ischemic shock.38 FIGURE 3. Open in new tabDownload slide Right lateral radiograph of a dog with severe gastric dilatation-volvulus syndrome, showing massive gastric dilatation and malposition of the pylorus. The dog’s head is to the right and the pelvis is to the left. GDV was a major cause of death in MWDs for decades;39,40 however, GDV is a rare occurrence in DoD MWDs now, since performance of a prophylactic gastropexy was instituted in 2009 for all new DoD MWDs. In this procedure, a permanent surgical adhesion between the stomach and inner peritoneal wall is created during an elective procedure that prevents volvulus and has dramatically reduced the incidence of GDV and gastric dilatation in the MWD population. However, HCPs may still encounter emergently ill working dogs with GDV, because most contractor working dogs and allied working dogs are not routinely operated. GDV is a surgical emergency. Intervention is required, ideally within 4 hours of presentation, to correct the volvulus, assess gastric and splenic viability, and perform a gastropexy. A partial gastrectomy or splenectomy may be necessary.37 Initial management of canine GDV centers on initiating immediate shock therapy, followed rapidly by gastric decompression. The most rapid and effective method of gastric decompression for GDV is trocarization of the tympanic stomach using a large-bore over-the-needle catheter. Briefly, after the insertion point is identified and prepared for aseptic procedure, a 14-gauge decompression device (commonly used for needle thoracocentesis) is forcefully inserted through the skin and body wall and advanced firmly into the stomach lumen to relieve gas pressure. Decompression may need to be repeated if tympany recurs while the dog is prepared for evacuation or surgery. Multiple complications can occur, thus, intensive monitoring is necessary. BLUNT CHEST TRAUMA MWDs in respiratory distress typically have characteristic breathing patterns that help localize the problem; detailed descriptions of these patterns are provided. — Provide 100% oxygen to any dog showing signs of respiratory distress. — Use a face mask or “blow by” technique for conscious dogs. — Use orotracheal intubation or tracheostomy for unconscious, sedated, or anesthetized dogs. — Thoracic radiography and serial TFAST8 are useful in the diagnosis and treatment of pneumothorax (PTX), hemothorax (HTX), pleural effusion, pulmonary contusions, and pulmonary edema. Up to 50% of traumatized dogs have some form of thoracic injury.6,7,11,41–43 Pneumothorax and pulmonary contusions are most common. Rib cage trauma includes “flail chest,” rib fractures, intercostal muscle rupture, and penetrating wounds. Usually the defect is obvious, especially if “paradoxical” chest wall motion is noted. Adequate management involves careful handling, laying the patient with affected side down, minimizing restrictive chest bandaging, and providing analgesia. External splinting or surgical management is usually not necessary unless injury is severe or extensive or chest wall is compromised and prolonged interference with gas exchange and ventilation are evident. Pain can substantially interfere with gas exchange and ventilation. Alleviate pain once the patient is stabilized to improve oxygenation and ventilation, using systemic and local analgesia. Dogs are generally not overly sensitive to the respiratory depressant effects of opioids. Local nerve blocks and intrapleural analgesia administration work well and are readily accomplished. Pleural space trauma includes open, closed, and tension PTX, HTX, and diaphragmatic hernia. Open PTX requires immediate action. Rapidly clip hair from around the wound, and apply an occlusive seal over the wound. Apply a chest bandage to secure the seal. Delay wound closure until the MWD is stable. The presence of decreased lung sounds in a trauma patient with signs of respiratory distress, or rapid clinical deterioration in an MWD with respiratory distress is sufficient justification for needle thoracocentesis. — Use an 18-gauge, 1–1.5 inch hypodermic needle attached to sterile tubing, attached to a stopcock that is attached to large syringe to aspirate air and fluid. — Do not use needle decompression devices used in humans (e.g., 3.25-inch over-the-needle catheters) or insert the needle deep into the chest. Dogs have narrow thoracic cavities and use of these devices or deep insertion markedly increases the risk of internal major vessel and cardiac injury. — With the dog in lateral or sternal recumbency, insert the needle on the mid-lateral thorax in the sixth to seventh or seventh to eighth intercostal space. — Count forward from the last rib (#13) to locate the insertion site. In dogs, the intercostal artery, vein, and nerve run on the caudal aspect of each rib; thus, best thoracocentesis is obtained by inserting the needle or catheter in the center of the intercostal space or at the cranial aspect of a rib. The mediastinum in dogs is thin and typically ruptures; therefore, always tap both sides of the chest, even if a positive tap is achieved on one side of the chest, as air pockets and fluid can migrate. Repeated thoracenteses may be required to stabilize the patient. A negative chest tap does not always mean there is not an abnormal accumulation of air or fluid in the pleural space. A thoracostomy tube is indicated if negative pressure cannot be achieved with needle thoracocentesis, if large amounts of blood are aspirated, or if repeated thoracocenteses are required to maintain negative pleural pressure. For most MWDs, use fenestrated tubes that are 24–36 Fr. As dogs are flattened laterally, compared with people, chest tubes are generally inserted through the skin high on the lateral chest wall at the 9th–11th intercostal space, tunneled cranioventrally toward the point of the elbow, and passed through the chest wall 2–3 intercostal spaces cranial to the skin insertion site. The chest tube will ideally be oriented cranioventrally in the pleural space, to maximize removal of air and fluid. Consider deep sedation or anesthesia, local anesthesia, intercostal nerve blocks, and intrapleural analgesia. Patients with chest tubes in place MUST be monitored continuously! Consider continuous suction or intermittent aspiration. Emergent thoracotomy may be necessary, keeping in mind the caveats discussed previously. Thoracotomy in dogs is generally best done through a lateral thoracic wall approach, generally at the fourth to fifth or fifth to sixth intercostal space to afford optimal visualization. A median approach is more difficult and has higher incidence of post-operative complications. Pulmonary contusions are common. Auscult the chest for decreased lung sounds, which suggest either fluid (blood) or air in the pleural space, or pulmonary contusions. A patchy distribution of altered lung sounds may be noted, which helps differentiate parenchymal injury from pleural space trauma. A negative thoracocentesis suggests the presence of pulmonary contusions. Radiographic signs (mixed interstitial-alveolar infiltrates) may lag by 12–24 hours. Hemoptysis, especially of arterialized blood suggests significant pulmonary vessel trauma that typically carries a very guarded prognosis. Management of pulmonary contusions in dogs involves minimizing stress, providing oxygen supplementation, cautious intravenous fluid administration to prevent progression of contusions and/or development of pulmonary edema, and addition of colloids to fluid therapy plans to decrease the amount of lung water that may accumulate during shock resuscitation. Diuretics and steroids are not indicated in treatment of pulmonary contusions. Severe, life-threatening major pulmonary vessel hemorrhage may require resuscitative thoracotomy, as discussed. Ventilatory support may be required for animals that fail to respond to correction or stabilization of the primary respiratory problem and supplemental oxygen support. ABDOMINAL TRAUMA Suspect significant intra-abdominal injury in any MWD that presents with abdominal rigidity or sensitivity to palpation, increasing abdominal size over time, visible bruising of the abdominal wall, or failure to respond to or deterioration in face of aggressive trauma resuscitation. Wounds involving more than the skin and superficial subcutaneous tissues dictate detailed examination to determine if the body wall was penetrated. Most working dogs with blunt abdominal trauma can be managed without surgery. Urgent exploratory surgery is recommended for MWDs with penetrating abdominal trauma or ruptured viscus organs. Perform an AFAST exam during the initial evaluation phase of every MWD presented for care with a history of trauma or acute collapse or weakness. AFAST is extremely reliable in detecting free abdominal fluid and can be performed rapidly during resuscitation.9 Examine four quadrants, just as in humans; the technique is detailed. Perform serial FAST exams every 4–6 hours and compare results: exploratory surgery may be necessary for MWDs with progressive fluid accumulation, failure to respond, or clinical deterioration. Additional diagnostic tests that are helpful in differentiating abdominal injuries include abdominocentesis, diagnostic peritoneal lavage, computed tomography, and detailed ultrasonography; these are discussed. The usual organs in MWDs subjected to blunt trauma are the spleen, liver, and urinary bladder, in this order of frequency.7,41–43 Most hemoperitoneum cases in MWDs are due to splenic and hepatic fractures, which can vary markedly in severity, with a significant difference in quantity of blood lost into the abdomen. The majority of MWDs with blunt abdominal trauma and intra-abdominal hemorrhage that survive to admission can be successfully managed conservatively.9 Monitor the MWD closely; some will require exploratory laparotomy and surgical correction of hemorrhage. Do not apply an abdominal counterpressure bandage on a MWD. Patients with massive intra-abdominal bleeding need surgery to find the site of bleeding and surgically correct the loss of blood. There may be instances in which emergent laparatomy is necessary by HCPs to afford a chance at patient survival. Urinary bladder rupture, with uroperitoneum, is fairly common.7,41–43 Repair of acute urologic injuries must wait until the patient stabilizes. Urologic injury may not apparent for several days after trauma; ultrasound and excretory urography studies may be necessary. In patients with known urologic tears and urine leakage, use abdominal drains if surgery is delayed for several days. The removal of urine will minimize chemical peritonitis and electrolyte and acid–base imbalances. Fluid therapy to correct or prevent electrolyte and acid–base imbalances is often necessary. Patients with a ruptured gastrointestinal viscus are candidates for emergent exploratory surgery. Broad-spectrum antibiotic therapy is vital, especially against anaerobic and gram negative bacteria; drugs and doses are provided. Shock management is of special importance. Every attempt must be made to stabilize the patient as much as possible, with URGENT evacuation to a veterinary facility for definitive repair. Exploratory laparotomy as a diagnostic and therapeutic modality is clearly indicated in trauma patients if penetrating trauma is highly suspected or known, and if the patient’s status deteriorates despite aggressive resuscitation attempts and major organ hemorrhage is suspected or known. Surgical management includes an approach through the ventral midline under general anesthesia, with the dog in dorsal recumbency, to expose the abdominal cavity. A complete abdominal exploratory is necessary to define all injuries. Routine exploratory techniques used for humans are appropriate for dogs. Surgical management will depend on the injuries noted. Repair of injuries in the dog is essentially the same as repair in human casualties. Abdominal wall closure is in three layers: 0 non-absorbable simple continuous linea alba closure; 2–0 absorbable simple continuous subcutaneous closure; routine skin closure. Dogs are prone to seroma formation, so careful closure of subcutaneous “dead space” is important. OTHER MEDICAL CONSIDERATIONS The full CPG discusses diagnostic imaging guidelines and protocols, and management of mesenteric torsion, long bone fractures, wounds, traumatic brain and spinal cord injury, and canine post-traumatic stress disorder. Additional information is provided for management of blast, burn, and crush injuries, snake and scorpion envenomation, ocular injuries, and toxicoses. Guidance is provided for humane euthanasia. REFERENCES 1 Fletcher DJ , Boller M, Brainard BM, et al. : RECOVER evidence and knowledge gap analysis on veterinary CPR. Part 7: clinical guidelines . 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TI - Trauma Management of Military Working Dogs
JF - Military Medicine
DO - 10.1093/milmed/usy119
DA - 2018-09-01
UR - https://www.deepdyve.com/lp/oxford-university-press/trauma-management-of-military-working-dogs-ZrPy0niwRU
SP - 180
EP - 189
VL - 183
IS - suppl_2
DP - DeepDyve
ER -