Puppy neural development and conditioning

Introduction

Working and performance dogs are career athletes that are subjected to a unique set of physical demands. Stakes are high for these dogs, as both their own safety and that of many people depend on their ability to carry out their duties with speed and agility. The dogs will often be called upon at a moment’s notice to engage in pursuit at sprinting speeds or to navigate varied terrain in a search exercise. Furthermore, intensive resources are involved in the training of these specialized dogs, so there is much incentive to maximizing the time at which they are at peak performance. Ensuring these dogs are appropriately conditioned is a critical aspect of their care and of preparation for any event that may call upon their services. Conditioning and functional neuromuscular training should begin in puppies bred as working and sporting dogs; based on evidence from human sports, this early start is expected to optimize performance and reduce the risk of injury.

Of course, not all puppies are destined for working status, but the same principles of conditioning that are applied to the working dog can also be applied to the puppy intended for family life. Training a puppy in the fundamentals of exercise can have a substantial pay-off when carried into adulthood. As with the benefits of exercise in humans, a foundation of conditioning helps maintain weight, contributes to a healthier metabolic profile, decreases the risk of injuries and certain chronic diseases, and facilitates pain-free movement throughout the dog’s lifetime.

Physical demands on performance dogs

To develop conditioning programs for high-level working and sporting dogs requires a thorough understanding of the physiological and biomechanical demands placed on these animals during their regular activities. Dogs participate in a range of activities from recreational pursuits to high-end athletic competitions and working dog duties. The exercise involved can fall anywhere along the spectrum from low to high intensity – a dog may be a “weekend warrior” hiker or may be a high-end performer in competitive sports, search and rescue, sprinting or long-distance running. Most of these active dogs will be required to sprint, jump obstacles, turn sharply at top speed, scale walls and fences, move on unstable surfaces, and withstand potentially severe compressive and bending forces to the spinal column at some point in their activities. Scent detection requires searching of rooms, large tracts of land, vehicles and other areas, often in places that may require crawling or navigating unstable terrain without fatiguing (Figure 1). Therefore, many physical attributes, such as strength, endurance, flexibility, proprioception and balance, are necessary for peak performance in active dogs. Several of these capabilities can be safely introduced in puppyhood, taking into account breed, age, diet, environment and other factors that influence puppy development.

Musculoskeletal injuries in performance dogs

Knowledge of the types and frequencies of injuries sustained by performance dogs during activities allows incorporation of preventive strategies into a training program. There is information in the literature with regard to musculoskeletal injuries sustained by working and sporting dogs, although some of the evidence has relied on owner or handler recall rather than documented diagnosis by a veterinarian. One study that retrospectively evaluated 245 military working dog (MWD) records to determine reasons for discharge from service found that spinal cord disease and/or degenerative joint disease (DJD) were responsible for 56.3% of discharges in dogs five years of age or older 1. Similarly, an earlier retrospective study of records from 927 MWDs reported that appendicular DJD (19.2%) and spinal cord/cauda equina disease (15.6%) were two of the top three reasons for death or euthanasia 2. A study of MWDs treated for non-combat injuries while deployed to Iraq showed that musculoskeletal injuries were the fourth most common reason for seeking veterinary care 3 and a report comparing emergency veterinary visits for police and pet German Shepherd Dogs noted that the police dogs were more likely to be seen for orthopedic injuries than the pet population 4. Significantly, handlers of police dogs in New Zealand reported normal function in only 29% of their dogs, and that functional assessment declined appreciably with age 5. Search-and-rescue dogs deployed in the aftermath of the September 11, 2001 terrorist attacks were found to have two orthopedic or spinal problem events per 1,000 dog search hours 6, whilst a retrospective web-based survey of agility dog handlers found that at least one injury was reported in 32% of training and competing dogs 7. A near-identical injury rate (33%) was reported in agility dogs with another survey of handlers 8, and noted that 58% of those injuries occurred during competition. In summary, musculoskeletal injuries and diseases appear to play a key role in medical intervention and retirement from duty or competition in performance dogs, demonstrating a critical need for the development of prevention strategies.

Programs for injury prevention and performance enhancement

Incorporation of neuromuscular training programs has been instrumental in reducing the risks of musculoskeletal injuries in youth and adolescent human athletes. Such programs varied among studies, but in general they incorporated the use of exercises that focus on balance and proprioception, plyometrics and coordination. Programs implemented for six weeks or more into the training curriculum for various youth sports have demonstrated a reduced incidence of sports-related lower extremity injuries 9 10 11, specific injuries such as anterior cruciate ligament tears 12 and ankle sprains 13, as well as an increase in balance and body awareness 14 among young athletes. Most studies to date in the body of evidence have focused on middle school and high school-aged children; injury prevention and performance improvement in younger children, and comparison of specific training programs, should be incorporated into future investigations.

Poor conditioning appears to be a major risk factor for sports-related injuries in young human athletes, and many working dogs are surprisingly inadequately conditioned despite the physical demands required by their duties. Some injuries sustained by human athletes have similar counterparts among working dogs, and analogous intervention strategies incorporated at the puppy stage are therefore likely to reduce injuries sustained during duty performance in these dogs. These programs, such as exposure to novel surfaces, obstacles and interaction with people, are expected to confer additional benefits to working dog puppies including navigation ability, confidence, body awareness and proprioception. To the authors’ knowledge there are no published evaluations or designs of programs that safely and effectively align with periods of puppy growth. Development of neuromuscular training programs at appropriate stages of growth requires an understanding of puppy neural development; this can be related to the stages of development in children.

Human neural development and impact on athletic performance

Children appear to develop neuromotor skills in a cephalocaudal (head towards lower extremities) and proximodistal (trunk toward distal extremities) direction. They are in a reflexive movement phase for the first year of their lives, during which they learn more about their body and the world around it; this influences neural networking between the body and brain. Initially primitive reflexes, such as rooting and suckling, are present. Postural reflexes then begin to develop in preparation for voluntary movements that will be conducted later. These include the righting reflex, which assesses balance, the crawling reflex, which will give way to voluntary locomotion, and the palmar grasp reflex. Throughout the first year of life the infant learns to gain control of the head and neck for stabilization and initiates unrefined voluntary movements. These movements begin to be controlled at around one year of age, which allow more directed movements of extremity segments and intentional manipulations of objects and the environment.

Within the “fundamental movement” phase, which occurs at 3 to 7 years of age, children explore bodily motion and the potential for movement in increasingly complex ways. Actions are initially uncoordinated and tend to be exaggerated, with gradual improvement in control and precision during the emerging stages at 3 to 5 years of age. This includes development of actions such as running and jumping, balancing on a beam or on one foot, and – by the latter stage of this phase – throwing and catching objects. This period of growth invites manipulation of a variety of fundamental skills required for athletic performance. This is critical, as environmental stimuli greatly influence the development of the fundamental movements during this timeframe. In fact, some adults may remain in these emerging stages for certain activities if they are not practiced and refined by external manipulation. At 7 years of age and beyond, children will improve simple skills for activities involved in daily living, but depending on environmental, cultural and inherent influences, they will also continue to develop increasingly complex and very precise movement sequences required for specific sports by age 13. At age 14 and beyond, the “lifelong learning” phase, children practice and utilize skills that will ultimately impact the distinction of elite athletes from other individuals, along with genetic variations. There is tremendous potential here for improvement of skill development, and most of the research in young athletes is targeted at this age group. Attempting to develop specialized skills at inappropriate stages of maturation appears to be of limited benefit 15.

Puppy neural development

As expected, a puppy’s central nervous system develops considerably more rapidly than those of humans. Puppies achieve spinal cord maturity at six weeks of age and have a mature brain with 96% adult-like brain function by four months of age 16. However, the direction and sequence of neuromotor development appears to progress similarly to that of humans. Puppies are born with intact vestibular function so that they can appropriately position to nurse. They are not born with muscle coordination or limb support, but will develop an upright posture at 10 to 14 days of age (Figure 2). Initial supported stepping with thoracic limbs is observed at 5-6 days after birth, followed by supported stepping with the pelvic limbs at 7-10 days. By two weeks of age, puppies are able to support weight on both thoracic and pelvic limbs and at 18-21 days they are able to ambulate with an uncoordinated gait. Spinal and myotatic reflexes can be initiated within a few days of life, but are weak and difficult to interpret until 3 weeks of age, when muscle tone is more developed. Tactile placing of limbs (thoracic first) becomes consistent at 5 weeks of age, while by around 6-8 weeks (although some breed variation exists) adult posture and balancing will be demonstrated, including postural reactions of the thoracic, followed by pelvic, limbs 17.

Behavioral development of puppies includes the sensitive period of socialization, which ends at 13 weeks of age. Manipulation of the environment and exposure of working dog puppies to a variety of visual, auditory and tactile stimuli are critical during this timeframe. Appropriate exposure of puppies to kennels, home environments and people has been shown to result in a significant reduction in stress and altered behavioral outcomes (Figure 3), leading to improved performance in working dogs 18.

Genetic attributes such as body composition influence performance in non-human species as well, but these capabilities can be dramatically enhanced with appropriate environmental manipulations such as neuromuscular training. One study in horses 19 showed that only about 35% of speed performance could be explained by genetics, while the remaining 65% was due to environmental factors such as nutrition, training and management. Whilst little has been studied in this area in dogs, early conditioning may, to some degree, overcome suboptimal genetic attributes in the canine species. Exercising working dog puppies five days a week in a controlled environment has been shown to yield improved drive and confidence scores, as well as better performance on a number of tasks required for detection canines in the United States Transportation Security Administration 20. These puppies were compared to those that exercised formally for one hour per week, so it is unknown whether there is a critical minimum frequency that would deliver the desired performance results. Customs dogs in Australia demonstrated capabilities that predicted their performance as adults to some extent by three months of age 21, and positive reinforcement was correlated with increased success, suggesting that interventions that impact neural development may benefit puppies under 12 weeks of age.

Puppy neuromuscular training

Early puppy socialization is critical for development of the human-animal bond, resilience and appropriate communication with people, whether as working and performance dogs or as companions. Socialization programs consist of exposing puppies to an extensive variety of novel stimuli, including humans, animals and different environments. The impact of such programs is even more significant for puppies raised in a professional breeding establishment or a working dog kennel. Puppies in their first weeks of immobility are sensitive to limited tactile, thermal and locomotor stimuli, so handling and other physical stimuli should therefore be integrated into the puppy’s experience bank within the first three weeks of life 22. A program was assessed in a population of working dog puppies that involved application of stimuli between the third and sixteenth day after whelping. Manipulations were conducted once daily for 3-5 seconds at a time, and included changing of head and body position, application of interdigital tactile stimulation, and thermal stimulation (by setting the puppies momentarily on a refrigerated, damp towel). Puppies that received these interventions were found to be more exploratory and active, more assertive in competitive situations, and calmer with fewer distress signals and errors in a problem-solving scenario 23

Puppy conditioning programs should focus on balance and stability, basic functional fitness and – eventually – skills targeted to specific activities. As puppies enter their third week of life and begin uncoordinated movement, more specific interventions in motor learning can be implemented. Supported, static balance can be introduced by placing the puppy in a standing position on a slightly unstable surface such as a foam cushion. As the puppy begins walking and improving its coordination (from three to six weeks of age) balance activities can become more dynamic – for example, allowing the puppy to walk across an undulating surface such as foam pads or a mattress. After tactile placing emerges at five weeks of age, small obstacles and variations in terrain can be introduced for the puppy to navigate.

Proprioceptive training is critical, particularly for the pelvic limbs, as untrained dogs typically have insufficient body awareness in the hindlimbs for safe and coordinated obstacle navigation. At 12 to 16 weeks puppies can be asked to undertake more demanding tasks, such as stepping in and out of a box, walking across a moderately unstable surface using balance discs or other inflatable equipment, and turning around as they ambulate, introducing abduction, adduction and rotational movements into the training (Figure 5). Low-impact cardiovascular training can be implemented; brief, 30-second bouts of swimming or wading in water to chase toys are particularly beneficial (Figure 6). From 4 to 6 months of age puppies can be introduced to more complex functional tasks, such as position transitions (stand-sit-stand, stand-down-stand) on unstable surfaces (Figure 7), and gaining recovery from extreme positions. Combination movements such as turning while stepping over obstacles, and turning while crawling, can also be implemented. Task-directed and problem-solving activities such as navigating obstacles for a reward should be included, and swimming sets can be lengthened in duration (to 1-2 minutes at a time). Puppies from 6 to 12 months of age can be introduced to more specific and fine movement skills – e.g., stepping on ladder rungs, searching on unstable surfaces, ascending and descending ramps, walking with forelimbs on a rolling chair. This stage should also include refinement of fine motor movements in previously introduced functional skills. At 12 months of age highly specific skills training can be refined and targeted to maximize performance for definitive duty or athletic requirements; this includes the gradual building of complex agility movements and fast-paced, high-impact or explosive propulsion-based activities 16.

Safe conditioning programs should be implemented in puppies that correspond with their level of neuromotor development and that minimize risk of injury to structures such as open physes, which are among the most easily damaged structures in skeletally immature adolescents 24. In most large breeds the growth plates of extremities remain open until about 12 months of age, so whilst plyometric training is incorporated into many adolescent human sports programs, exercises that involve repetitive, high-impact forces (e.g., jumping down from a height, prolonged running) should be avoided in skeletally immature puppies.

The conditioning activities in this article are targeted to improving performance and reducing risk of injury in working dogs. However, these progressive manipulations of environmental stimuli are designed to benefit all puppies, from household pets to professional athletes. Dogs can be instilled with problem-solving capabilities, improved confidence and better performance during basic activities of daily living as well as complex functional tasks. Practitioners who understand the stages of canine neural development and motor learning, and utilize that knowledge to apply progressive functional training, can assist in developing puppies with stronger human-animal bonds, reduced risk of injury, and an overall higher quality of life in any capacity.