Injury prevention in service dogs

Introduction

In 2016, we said good-bye to the last service dog that assisted with the 9/11 Ground Zero rescue operations, and at times like these we are reminded how much we rely on these canine heroes who loyally serve and protect. Working service dogs (or K-9 units) are now commonly used in search and rescue, law enforcement, military operations and other aspects of security; in North America these include the Federal Bureau of Investigation, Customs and Border Protection, Transport Security Administration, Canadian Armed Forces, and Department of National Defense. The job description for these dogs varies immensely (Figure 1), and can include patrolling, tracking, detection (explosives, firearms, ammunition, narcotics, and cadavers), apprehension, as well as search and rescue for missing individuals or during a mass casualty event. Service dogs are invaluable members of a larger team and play an incredibly important role in protecting and promoting human safety. Because of their daily duties and potential for working in high-risk scenarios, ensuring their safety, avoiding injury, and encouraging career longevity is a primary focus for preventative veterinary healthcare.

Underlying conditions & working hazards

Depending on their occupation, service dogs come in many shapes and sizes, with certain breeds (because of their conformation) being better suited to perform certain tasks. The most common service breeds include, but are not limited to, German Shepherds, Belgian Malinois (Figure 2), Labrador Retrievers, Rottweilers, and Beagles. However, this can predispose to problems. Inherited orthopedic disease such as elbow dysplasia, hip dysplasia, intervertebral disc degeneration, patella luxation and cranial cruciate ligament disease can especially affect these breeds 1. One study looked at the prevalence of musculoskeletal conditions in service and working dogs and found that a staggering 41% of these individuals had a significant underlying orthopedic disease 2.

Other hazards are also encountered. Dogs deployed to disaster locations often succumb to illnesses such as dehydration and gastrointestinal disturbances, and search and rescue dogs often incur superficial injuries (e.g., wounds, abrasions, and paw, pad and nail injuries) due to environmental hazards 3 4 (Figure 3). Military and law enforcement dogs are prone to emotional distress and possible catastrophic trauma or weapon-related injuries due to their job requirements.

Injuries

Individuals working with service dogs need to be proficient at providing not only emergency critical care but also dealing with many other problems. In addition to underlying orthopedic disease, the musculoskeletal system is involved in up to 14% of non-combat related injuries in service dogs 5 and these can further impact on a dog’s performance and career longevity. For example, retrospective surveys of agility handlers found that ~30% of competing dogs had suffered at least one sport-related injury 6 7, with the documented injuries being due to inappropriate contact with objects and uncontrolled movements such as turning, twisting, slips, and falls. Many of these were soft tissue problems, predominantly affecting the shoulder, back and neck, and it is assumed that many of these injuries are likely the result of chronic and repetitive overuse. Service dogs are expected to work in unpredictable environments with inconsistent terrain and variable obstacles, and are likely to move at high speed, and it could be anticipated that, as with agility dogs, service dogs may sustain similar injuries from chronic overuse. Certain common injuries and problems have been identified in service dogs.

Carpal injuries

Due to the demands of jumping, the carpal and shoulder joints are particularly prone to impact. Carpal hyperextension injuries are usually traumatic and result from jumping down from heights or working on uneven terrain. The carpus is a complex structure where stability is achieved by supporting ligaments, tendons, and palmar fibrocartilage, and repetitive jumping could perceivably increase the risk of degeneration of these supporting structures. It may therefore be well worthwhile introducing controlled exits when leaving service vehicles for these dogs.

Fibrotic myopathy

This is a unique soft tissue condition that causes a biomechanical lameness involving the pelvic limbs. Active working shepherd dogs appear to be most susceptible to this disease, with reports that 90% of affected dogs are German or Belgian Shepherds, with approximately 40% actively involved in protection work 8. This disease involves normal muscle tissue being replaced by fibrous, non-elastic connective tissue. The gracilis and semitendinosus muscles are predominantly affected, and it is significant that they share some common characteristics (Box 1). The result is a functional shortening of the affected muscles and a mechanical lameness from an inability to extend the stifle. Chronic, low-grade microtrauma of muscle fibers from excessive and explosive activity may be the initiating factor for this fibrotic process. The most effective treatment or intervention strategy is unknown at this time, but the possibility that this disorder is related to repeated muscle injury suggests that a targeted stretching program may be valuable in reducing the prevalence. Regular myofascial assessments may also encourage earlier detection and possibly more successful interventions in the future.

Lumbosacral disease

An increase in the prevalence of degenerative lumbosacral stenosis is a concerning trend in military working dogs, as it negatively impacts not only on career longevity but on quality of life and lifespan. One study reviewed the medical records of 927 military working dogs and found that degenerative joint disease (19.2%) and spinal cord pain/cauda equina disease (15.6%) were common reasons for euthanasia 9, whilst another study reported that 30% of military working dogs suffered spinal cord disease and was a common cause for retirement 10. Physical activity-related strain and breed-associated structural uniqueness may encourage changes to the lumbosacral region and cause degenerative lumbosacral stenosis, which can contribute to altered biomechanics, nerve-related or neuropathic pain, and neurological dysfunction 11 (Figure 4).

Conditioning programs

A significant focus in canine athletics and veterinary sports medicine has been the concept of injury prevention. Avoiding problems in service dogs is important, as injuries ultimately impact an individual’s performance and dogs may be forced into early retirement due to injuries acquired. Many dogs have been selected because they have the desired conformation and behavioral characteristics to perform their jobs effectively and efficiently. Our role is to improve their ability to perform and work without injury by influencing their physical fitness.

Fitness on both ends of the leash is required for a team to function well, and there are many benefits to a conditioning program, including encouraging high performance, reducing risk of injury and improving recovery following an injury. A program should be targeted towards the needs of each individual dog and its occupational role, as different tasks can lead to different physical demands and stresses on the body. Historically, proper conditioning of service dogs is often a challenge due to time management, but in order to achieve longevity and durability, the overall conditioning of a dog needs to exceed its drive. Ideally, conditioning should be considered an additional activity above and beyond regular skill training and work duties.

A conditioning program for individuals requiring enhanced endurance should focus on maximizing oxygen utilization, whilst a program for animals requiring strength should focus on increasing power and acceleration. A high level of endurance is important for service dogs involved in prolonged periods of activity (such as tracking) while strength is important for animals involved in short bursts of high intensity 12. Service dogs are unique athletes that require a combination of aerobic and anaerobic conditioning to advance their overall strength and endurance capacity. The prime objective of a conditioning program is to maximize a dog’s physical fitness and improve both the cardiovascular and musculoskeletal systems. The program should allow for gradual increases in duration, frequency, and intensity of exercises to allow the cardiovascular and musculoskeletal systems to accommodate and adapt. An ideal condition program incorporates endurance, strength training, balance and core strength, proprioception, stretching, warm-ups and cool-downs.

Endurance

Improving endurance in the service dog can have an impact on maximizing performance and minimizing fatigue. Exercises that lead to increased heart and respiratory rates will target endurance development, and examples of endurance activities include continuous swimming and jogging. The preferred gait when working on land for endurance training is the trot, a symmetrical 2-beat gait that exercises both sides of the body equally compared to a gallop or canter. Increasing the length or volume of training is not always the solution for making endurance gains; it has been found in highly trained human endurance athletes that performance improvement can only be achieved through high intensity interval training. In other words, a sprinting program in addition to endurance training is utilized for long distance runners 13.

A lack of conditioning can result in poor endurance, fatigue issues, and/or heat exhaustion. The prevention of overheating is a major concern for working dogs in a hot or humid environment, and endurance training encourages the body to respond with improved efficiency. Handlers cannot control environmental temperature, but an individual dog’s physical fitness impacts their thermoregulation and internal body temperature. A lack of conditioning results in an increase in body temperature, excess panting, and mouth breathing, which ultimately influences olfaction and impacts scent detection abilities. Certain medications, such as metronidazole, can also impact olfactory senses and should be avoided or used with caution in service dogs involved in detection 14.

Strength

Strength training in humans often refers to resistance training with weights or power training, which involves a combination of strength and speed (i.e., plyometrics). In canine athletes, strength training involves having the dogs move their own body weight over short distances. Agility equipment is excellent for strength training as it requires the dogs to move over, under, and through obstacles. Equipment items like tunnels force the dogs to move their bodies lower to the ground and will challenge the thoracic limb muscle groups of the shoulders, including biceps, triceps, and pectorals. Obstacle course equipment such as the catwalk, A-frame, steps, weaves, and jumps target the pelvic limbs and paraspinal musculature (Figure 5).

Balance and core strength

The core muscles in the dog include the abdominal and paraspinal muscles, which play an important role in stabilizing the body during movement. Improving strength in these powerhouse muscles enhances functionality and the ability to perform agile movements. There is a significant amount of stress placed on the back with the sort of movements performed by service dogs, and without core strength the back is not appropriately supported and can be injured with rotational torque and explosive types of activities (Figure 6). It has been found that dogs with degenerative lumbosacral stenosis have paraspinal muscle atrophy, which is also a common finding in humans with chronic lower back pain 15. Working on core strength is invaluable when dealing with breeds or conformations that are predisposed to spinal cord disease, and studies are currently under way to determine what role a conditioning program can have on increasing the mass of paraspinal muscles in dogs with mild or moderate lumbosacral pain. Many exercises performed on inflatable equipment focus on balance and will encourage the development of core strength (Figure 7).

Proprioception

Proprioception refers to the concept of spatial awareness, i.e., the body’s ability to sense movement and acknowledge where the limbs and joints are in space. Proprioception is required for everyday functioning but is even more critical for the performance of coordinated and complicated sporting movements. The proprioceptive system is made up of special nerves that relay information, and this system can be challenged with training, which can have a positive impact on coordination, agility, stability and balance, as well as reducing the risk of injury. Enriching the training environment by working on a variety of terrains, inflatable equipment, cavalettis, and agility or obstacle course equipment are easy ways to challenge a dog’s spatial awareness.

Stretching

Stretching involves placing a small amount of tension on a muscle and is effective at increasing not only muscle flexibility but also joint mobility. In addition to minimizing muscle injury, a regular stretching program in humans can increase the force and velocity of muscle contractions, resulting in more muscle power. There is a lack of consensus in human studies regarding the use of “pre-event” stretching to reduce the risk of injuries. It is thought that stretching immediately before an event may actually reduce muscle performance by decreasing the velocity and force of muscle contractions 16. The main benefit with improving muscle flexibility is to reduce the risk of micro-tear injuries. It may be beneficial to initiate a regular hamstring stretching program in breeds that are at high-risk for developing fibrotic myopathy (Figure 8a) (Figure 8b) (Figure 8c). The greatest gains in flexibility are achieved when stretching occurs on a regular basis over time. Ideally a stretching routine should be performed on muscles that are warm, as there is an increase in extensibility and compliance of the tissue. A stretching program to the muscles that contribute to rapid busts of power should be considered for canine athletes, performed on alternate days.

Warm-ups

An active warm-up session results in an increase in muscle temperature and ensures an adequate supply of oxygen to the muscles. This allows them to contract more powerfully and improves muscle extensibility, thereby reducing the risk of injury. Working muscles receive a greater proportion of the bloodflow which can assist in the removal of lactic acid, a common by-product of muscle contractions which may play a role in fatigue. A simple 5-10 minute warm-up, consisting of low impact actives such as walking and trotting, can help prepare the dog’s muscles for future training and work challenges. Ideally, warming-up prior to exercises, conditioning, or work-related activities when time permits will assist with improving performance and preventing injuries 17. Consider adjusting the length of warm-up relative to the environment temperature (i.e., longer warm-ups in cooler weather and shorter in hot/humid weather) 18.

Cool down

The cool-down period can be just as important as the initial exercise or activity. The main goal during this time is to bring the respiratory rate, heart rate, and body temperature slowly back to normal. As noted above, a common end-product of vigorous muscle contractions is lactic acid, which can cause a reduction in pH and may result in muscle fatigue and discomfort. Cooling down over a 5-10 minute period with light trotting followed by walking allows the blood supply to redistribute and can help remove excess metabolic by-products. This cool-down routine also provides “high-drive” service dogs an opportunity to unwind emotionally prior to being confined or returned to a vehicle.

Injury & rehabilitation

Injuries are bound to occur due to the nature of the work required by service dogs. Muscle injuries are extremely common in both human and canine athletes and can be acute or chronic in nature. They may be the result of poor flexibility, inadequate warm-up, fatigue, sudden forceful contractions, strength imbalances, and over-training. Acute muscle injuries are a consequence of muscle fibers tearing suddenly, while chronic injuries are an accumulation of minor tears that have never healed appropriately due to constant overuse (Figure 9).

Rehabilitation is an appropriate standard of care when dealing with any underlying orthopedic disease or musculoskeletal injury to assist with recovery, minimize risk of re-injury, and encourage return to work in a service dog. Most tissues undergo similar stages of healing, i.e., inflammation, repair, and maturation. It is during the repair phase that rehabilitation can ultimately guide healing to maximize tissue strength (Figure 10). Typical stages of rehabilitation include an acute phase, an intermediate phase, an advanced strengthening phase, and a return to sport or work-specific training. Proprioceptive abilities will often be deficient following an injury and can result in subtle changes to muscle control. Improving proprioception through specific exercises can help return to a competitive level.

During any prolonged medical illness or following abdominal surgery (e.g., gastric dilatation / volvulus, foreign body removal, splenectomy), it is important to acknowledge that the body undergoes a state of deconditioning. There is loss of both cardiovascular fitness and musculoskeletal integrity when exercise restrictions are in place. A structured rehabilitation program focuses on the concept of gradual return to activity to ensure that the dog is physically ready, regardless of its mental determination to return to work.

Early injury detection

Comprehensive screening to ensure a solid orthopedic foundation and regular musculoskeletal examinations or “sports assessments” for service dogs will encourage earlier identification of musculoskeletal issues (Box 2) (Figure 11). These musculoskeletal conditions can predispose this patient population to performance issues due to underlying pain or earlier progression of a disease process from excessive wear and tear.

The combination of drive and adrenaline in service dogs often masks the early signs of an injury. Mild injuries can be a challenge to detect, as there are minimal tissue changes on physical examination. In humans with mild strains, the description of discomfort is often the key factor in diagnosis. It is important for handlers to routinely perform a quick “5-minute evaluation” of their dogs after strenuous work shifts (Box 3). With regular palpation, a better understanding of what is “normal” for a dog can be developed, and this increases the chances of detecting an initial minor change (Figure 12). The ability to identify an injury in its early stages is invaluable for both successful intervention and in preventing a minor injury from progressing or escalating to a more chronic performance-altering condition.

Long-term joint health

Encouraging ideal body condition in service dogs is paramount for both long-term joint health and overall performance. Dogs that are in shape can perform job-related tasks better, whilst excess weight contributes to thermoregulation difficulties and impacts on scent detection. As the body condition score escalates, the shear force on the joints increases, as does the susceptibility to injury. Obesity increases not only the occurrence but also the severity of osteoarthritis. It is often quoted that 20% of adult dogs are impacted by osteoarthritis, but a recent study revealed a prevalence of 37% in dogs greater than one year of age 19. The number of overweight dogs is rapidly increasing and evidence suggests an association between lifespan and body condition score 20; it has been shown that dogs fed a limited calorie diet developed osteoarthritis later in life and had a longer life expectancy in comparison to dogs on an ad lib diet. 21 22 23 24

Arthritis is the number one cause for pain in companion animals, and the pain from arthritis can directly impede performance in canine athletes and service dogs. Due to their job demands, service dogs are at an increased risk for excessive wear and tear on their joints. Degenerative joint disease causes alterations in movement which results in overcompensation by other joints and muscles. These changes can cause muscle fatigue and increase the susceptibility to injury. Focusing on the prevention of arthritis, early arthritis identification, and the implementation of a multi-modal arthritis plan (Box 4) is paramount for extending the career life of service dogs.

It must also be emphasized that nutrition plays a significant role in not only providing an appropriate fuel source but also by mitigating disease risk and progression. There are many different nutritional supplements and diets available with the primary goal of supporting long-term joint health. As part of a multi-modal arthritis plan, it is common to utilize chondroprotective agents to slow down the progression of osteoarthritis. Frequently used products include, but are not limited to, omega 3 fatty acids from fish oils (EPA & DHA), avocado soybean unsaponifiables (ASU), curcumin, green tea extract, green-lipped mussels, glucosamine, and chondroitin sulfate.

Preventative health care has come a long way with regards to physical examinations, dentistry, laboratory screening, nutrition, parasite control, and vaccinations for service dogs. The emerging field of sports medicine focuses on influencing the physical fitness of these animals and promoting career longevity, which ultimately fosters the bond between handlers and working dogs, and with a good knowledge base the veterinary healthcare team can play a vital role by implementing appropriate strategies to maximize injury prevention.