“Dogs in Motion – coherence of the skeleton, muscles and motor skills”
The domestication of the wolf has led to an amazing variety of breeds in size, weight, body shape and general appearance. The reasons for the wide variety of our pets, wolves in its inherent variability and the effects of thousands of years of artificial selection. The investigation also focused bred to changes in the musculoskeletal system.
With the largest global study ever on the locomotion of dogs in 327 dogs from 32 breeds, the team of Martin Fischer has studied how breeding policy affects the movement of various races, especially when you consider that, for example, a forty-fold difference in weight between the Chihuahua and a Dachshund or Dog. Or moving dogs, regardless of breed continues the same?
This seminar will extensively cover the basics of the locomotion of dogs, supported by films and animations. Particularly interesting are the videos made with the latest X-ray equipment, the movement of our dog. New discoveries concerning joint load balance during movement, activity and inactivity of certain muscles, amplitude of motion in the joints and connective tissues of tax are discussed.
The results of the entire study are presented in a book “Dogs in Motion,” in which the latest insights into the locomotion of dogs are treated extensively. Readers get comprehensive information about bones, muscles, joints, movement and acting on dynamic aspects. Through a unique visual language and a DVD with over 300 films (high-speed X-ray films and especially 3D – animations), opening the door to a new understanding of the movement of our dogs.
The book Dogs in motion is suitable for everyone, and available in English and German.
Lahmheitsuntersuchung beim Hund, is written for veterinarians and therapists and only available in German.
DOGS IN MOTION
Prof. Dr. Martin S. Fisher ©Dogsymposium Holland 2017
Most problems in human-dog relationships are a problem of understanding, not of hierarchy or command. Martin Fischer, professor of systematic zoology and evolutionary biology: ‘Dogs do hijack the human bonding system, and give us the feeling they belong to us. Each dog needs a bonding system, but we have to accept that they live in another world: dogs are not us. Endocrinology, the science of hormones is the key to instrumentalize dog behaviour. Martin Fisher’s Jena study of dogs in motion (2011-2016) explains why dogs move like they do and how this can affect their health.
Human attention changes the facial expression in domestic dogs. A recent article by Juliane Kaminski (October 2017) describes how dogs change their facial expression when they look at you trying to get your attention.
Dogs are the only mammals that can look us in the eye without getting aggressive. They make our oxytocin level rise. The oldest evidence of a human buried together with a dog was found in Ein Mallah, Israel and dates back 12.000 years ago. In the late Upper Paleolithic dog burials were prolific. The first Plaleolithic domestication of the wolf took place before the advent of sedentism, during the age of hunter-gather-societies. It is possible that domestication took place a second time, in the ‘Fertile Cresent’ region at the beginning of the Neolithic between 12.000 and 8.000 years ago. Dogs became smaller in connection with human sedentism and may have been selected on the basis of new criteria.
However, in 2009 the Belgian researcher Germonpré re-examined a skull that had been found in the 1860s in the Goyet Cave in the valley of the Samson river. It seemed this skull was 31.700 years old. The skull shows changes that can be interpreted as the result of domestication: shortening of the muzzle-region and changes in the cranium and teeth. If this skull came from a dog, it can indicate that the domestication process of dogs started earlier than 12.000-14.000 years ago.
Dogs have the same sensitive system as humans, but their view is different. They see less colours, but can see better in dawn and are able to see 80 pictures per second. Dogs are made to chase moving objects in scarce light. They live in a whole different world. Dogs ancestors, wolves, were made to move 40-50 kilometres a day. Their territory is as big as the island Elba (230 square kilometres). If a wolf doesn’t mark his territory with urine, he will lose it and another pack will kill him. That’s why wolfs depend on their family and no outsiders are tolerated. Canines are group hunters and cannot kill their prey by biting. They chase, exhaust, shake and bite their prey multiple times. This is a process of collaboration, and the reason why wolves have to be social. It’s a constraint in biology.
Because the ancestors of dogs were made to move long distances, their energy consumption had to be as low as possible. Trotting consumes least energy. A one hour walk and run will consume 5% of a dog’s energy, 2 hours will take 7-8% of a dog’s energy while trotting. Up to 90% of a dog’s daily energy consumption is needed for digestion (15-20%) and the ‘heating system’ (70%). The temperature of a dog has to be 38,5 degrees Celsius in all circumstances. The bigger a dog is, the less energy he will need.
The body surface of a big dog is less in volume compared to a small dog. Dogs that weigh 0-20 kilograms need more energy than dogs that weigh 20-60 kilograms. So: the bigger a dog is, the lesser food he needs. Nowadays most dogs are overweight, this not only causes problems evaporating the heat, but is hurting a dog in many other ways. Overweight dogs are prone to diabetes, cancer and are likely to have problems with their moving system. If you can’t see the body shape, a dog definitely is overweight.
Dogs in motion
The Jena study of dogs in motion was one of the most extensive studies into dog locomotion ever undertaken. Between 2006 and 2011 Fischer and his team studied 327 dogs from 32 regular breeds. Does a 2 kilogram dog move in the same way as a 68 kilogram dog? Which gait is most common for which breed? And what is the impact of body mass on locomotion? To record locomotion, different high frequency techniques were used: videography, marker based movement analysis and biplanar X-ray videography.
A gait is defined as a regularly repeated sequence of limb movements. The walk, trot and pace are classed as symmetrical gaits, in terms of rhythm and in terms of movement. The limbs of one side of the body do the same as the limbs on the other side of the body, although not at the same time.
The symmetrical gaits form a continuum, which means that the pace-like walk and the trot-like walk are equally possible. Gallop is just an umbrella term for various galloping gaits. The canter is the slowest form, diagonal and rotary are the two rapid gallops. The model gait of a dog, that is build in a wolf like manner, is a ‘perfect trot’: moving his 4 legs independently from each other, like a cat.
The centre mass, the balance point of a dog, lies between the sixth and seventh rib. During the walk, phases of two legged support alternate with phases of three legged support, though the phases of two legged support are very short. The advantage of this is that the body’s centre of mass almost always is located within the support triangle on the ground.
During the trot the body of a dog is supported by one diagonal limb pair at a time. Ideally, during the trot the body’s centre of mass remains at all times on the support line formed by the two limbs in contact with the ground. The ‘follow-leader-principle’ guaranteed that the hindlimb touches down on safe terrain. That is, if the dog is build in a wolf like manner, like a German Shepherd. A French Bulldog, for instance, has a round body. While moving, the centre of mass will go from left to right, up and down. This ‘drunken sailor gait’ costs a lot of energy. Most dogs prefer the trot, if they have to move long distances. It even costs less energy at a higher speed than walking.
The canter, the slowest form of gallop does not involve a flight phase: one legged support alternates with three legged support. During the diagonal gallop the touchdown of the leading hindlimb is followed by the touchdown of the forelimb diagonal to it. The trailing fore and hindlimbs are located on the same side of the body.
During the rotary gallop the limbs are placed on the ground either in a clockwise or an anticlockwise pattern. Touchdown of the leading hindlimb is followed by that of the trailing forelimb on the same side.
Out of balance
If a dog is pacing, his body is out of balance. During the pace, the body is supported by the fore and hindlimbs of the same side of the body. The centre of gravity shifts from one side tot the other and is usually not located above the line of support, and causes the slightly ‘rolling air’ of the pacing gait. Long time this gait was considered a pathological gait. But if dogs are pacing from the beginning, it isn’t pathological. These are considered rather intelligent dogs, because they have a broader repertoire of gaits. Similar to the Islandic so-called ‘gaited’ horses.
Horses with the ability to perform comfortable gaits (ambling or pacing) have been highly valued by humans, especially for long distance travel. Recently, the causative mutation for gaitedness in horses has been linked to a substitution causing a premature stop codon in the DMRT3 gene. In mice, DMRT3 is expressed in spinal cord interneurons and plays an important role in the development of limb movement coordination. Research done by Saskia Wutke and her team (2016), genotyping the position in 4396 modern horses from 141 breeds, revealed that nowadays the mutated allele is distributed worldwide with an especially high frequency in gaited horses and breeds used for harness racing. Dogs do have this mutation and therefore are able to develop a broader repertoire of gaits. It is said that a dog pacing on regular ground, is relaxing his back. But this has to be considered speculation, it’s not scientifically proven. However, when dogs start pacing at 4, 5 or 6 years, it is an indication of something pathological.
Markers and position of pivots
The rolling of the body, when a dog is moving, is a result of the way dogs are placing their feet. During the Jena study on dog locomotion, 22-30 markers were placed on each of the 327 dogs by Karin E Lilje, who worked on this project for five years. Because the markers were placed on the skin, the movement measured by the standard X-ray technique (2000 frames per second), did not indicate the movement of the bones, but movements of the skin. Results became more accurate using new X-ray videography up to 5000 frames per second. This software, also used in the Jurassic Park movie, produced rather fascinating 3D-animations that indicate the skeletons used in vet schools are wrong.
These models have a hip joint placed at the level of the shoulder. The anatomy model used by the Fédération Cynologique Internationale is based on one breed: the German Shepherd, which is a trotter. The longer they stride, the more impressive it looks. In order to achieve longer strides the dog’s hip had to be lowered, a misunderstanding. If this was true, dogs should have a rather deformed hindlimb.
The 3D-animation of a dog moving shows that this is impossible: a red dot placed where the dark lines of the shoulder blades meet, stays absolutely horizontal passing right through the hip joint, when the dog is moving. Dogs don’t move their shoulder while moving their forelimbs, they move their forelimb at the point of the shoulder blade – which is higher. It’s a pendulum mechanism, which helps the dog to save energy while walking in a straight line. But: a dog moving freely is never walking in a straight line. He is stopping, turning, running, resting etcetera.
The shoulder blade
The length of a dogs step is regulated by the degree of rotation of the shoulder blade. The movement of the forelimbs comes from the rotation of the shoulder blade, which is – unlike humans – not fixed to the body, but attached to it by three muscles above and below. Therefore the shoulder joint is a force driven joint, moved by muscles, and has no breed-specific locomotion. This is illustrated by 3D-animations of four different breeds moving, seen from the side: a Bulldog, a Beagle, a Malinois and a Whippet. The animations show that the position of the shoulder blade matches that of the hip, and the first segment of each limb matches that of the third. It remains parallel throughout the entire movement, especially at touchdown. When animals are landing after jumping, they do have a stiff forelimb, their muscles coordinate landing and make it possible to bend their feet up to 90 degrees. Knowing this, you can imagine the more body mass a dog has, the more relatively weak he will be on the forelimbs. That is why agility with dogs over 15-20 kg is not a good idea.
From side to walking towards you
Up till now we have been looking at dogs walking a straight line and examining them from the side. This research indicates the movements of hip and shoulders are the same for most breeds. But when we start examining dogs that are approaching us, we will discover differences in movements between breeds and differences in movements in one breed.
To be able to examine the rotation of a dogs joints, markers were not only placed on the joint, but also directly on the limb. The markers have a T shape, which gives better accuracy when the limb turns away from (abduction) or towards the dogs body (adduction). Different kind of breeds rotate their knees in another way, while the lower leg remains in place. This explains why several breeds are more susceptible to ruptures in cruciate ligaments. In humans most ruptures are almost always traumatic, caused by an accident. In dogs 95% of the ruptures in cruciate ligaments are degenerated, not traumatic.
The cruciate ligaments are mechanically destroyed.
© Amir Andikfar, www.andikfar-cgsociety.org
The recent NIH Dog Genome Project by Heidi Parker, Dayna L. Dreger and their team (2017) shows the Basenji is the most primitive dog, the French Bulldog is the least primitive. The least primitive dogs have more difficulties moving and therefore are more prone to ruptures in cruciate ligaments. Physical traits, the body shape and size of a dog, are determined by the genes of a dog. The majority of traits develop as a result of interaction between various genes (polygenic inheritance). In numerous cases, a change in one gene affects several traits at once (pleiotropy = polyphenism). There are also master genes which are responsible for the regulation of other genes.
The gene sequences responsible for the formation of quantitative traits are known as QTL’s (quantitative trait loci). Genetic studies by Chase et al (2002), Carrier et al (2005), Parker & Ostrander (2005), Lark et al (2006) have explored the connection between such traits, kinship, and correspondence between gene sequences. Almost all the anatomical traits of the 330 Portuguese Waterdogs in this research, were found to depend on body size and sex. But the studies also revealed some unexpected connections between pelvic shape, limb bones and skull shape, which are genetically coupled. The same connection was found in domesticated silver foxes (Truth et al, 2006). It appears that in canines, there is a basic regulatory mechanism which selects for ‘speed’ or ‘strength’. They differ in skull and pelvis shape, ribcage shape, position of limbs, distribution of body weight across the fore and hindlimbs and in the cross-sectional profile of their long bones.
©2002 National Academy of Sciences, U.S.A.
Different body types: speed and strength
A Greyhound (build for speed) has a long skull, slender, slim pelvis and elliptic shaped bones. A Bull Terrier, on the other hand, is build for guarding cows and bulls, and therefore has to be able to manoeuvre in many directions: turn around and kick in the face. He has a shorter skull, rounder pelvis and round shaped bones. These specific body shapes and sizes do have advantages, but also can have severe disadvantages. For instance, the flat snout of a French Bulldog takes off the cooling system. The bone material is blocking the respiration flow that is being pushed outside while inhaling, therefore they cannot cool the incoming air. All other structures (tongue, teeth, soft tissue) have the same size, but are squeezed in as snouts tend to get shorter. These French Bulldogs cannot breath properly and are not allowed to do any exercises when the temperature goes up to 25 degrees Celsius. This breed not only has problems breathing, but also is known as a very unstable dog that can suffer from ruptures in cruciate ligaments, hip and elbow dysplasia.
Joints and cartilage
Dogs are not made to move in a straight line, they need to turn, stop and move in various ways. It’s important to develop muscles and keeping the joints healthy. A joint is defined as the flexible connection between two or more skeletal elements. Diarthroses, ‘true joints’, are joints which possess an intra-articular space (joint cavity) between two cartilage-covered articular surfaces. Synarthroses are fusions of bone that are found in the sacrum, of cartilage (breastbone) or connections of taut connective tissue such as observed in the sacroiliac joint. Forces in true joints are transmitted as compressive and tensile strain, in synarthroses forces are transmitted through transverse or shear strain. Rotational axis in true joints are relatively fixed, in synarthtroses the rotational axis moves according to the forces at play. Articular cartilage is a soft, visco-elastic material with numerous pores. Only 10% of the total volume of cartilage is actually made of cartilage cells.
Joint cartilage is the only body part that is only been nourished from fluid of the joint (senovia). And only those surfaces in contact are being nourished. In a joint there is a small amount of fluid: the so-called synovial fluid, which has a mechanical function (dampening impact) and a nourishing function. The bone of a joint is fed by the vascular system and gets nutrients from the blood. Between the bone and the cartilage is an area known as the tidemark. Anything above the tidemark, like the cartilage, does not get its nutrients from the blood. It gets them from the synovial fluid.
When the joint is loaded with the animal’s weight, then released, the fluid moves into and out of the cartilage.
You can imagine that the bones of a dog that is constantly walking in a straight line, or is running next to a bicycle, are not being nourished. In trot there is less ‘bone-contact’ than in walk. That is why most guard dogs develop arthrosis when they are 5-6 years of age. The lower layers of the bone become calcified, the upper layer breaks. Instead of arthritis which develops due to inflammation, arthrosis develops due to degeneration; the cartilage starves – a process that can never recover.
The hip joint is a very crucial joint: all the motion and rotation in a dogs body comes from this joint. it is the hip joint that moves the hind leg. The hind foot makes contact with the ground, pushes up via the hip joint and the sacroiliac joint, and the hip joint then pushes the body forward. A dog that is suffering from hip dysplasia is an extreme indication of immobility and can be in a lot of pain, he sometimes will not even be able to scratch himself. To prevent cartilage of starving, especially in the hip joint, it is important that a dog can make different kind of movements on various terrain.
Mobility and motion
Another important factor in mobility is the fascia of a dog. When a dog trots there is a damping mechanism active. This ‘elastic energy’ comes from the fascia. The whole body of a dog is penetrated by this strong interwoven tissue. It looks like a thin white membrane and consist of 100% collagen. The molecule that makes up fascia, is helical (spiral). This is why it always returns to its original shape, like a gummy bear. Mobility and motion both depend on fascial release. It serves as power transmission, conducts lymph, possess different types of receptors, has numerous free nerve endings, and acts on the vegetative (autonomic) nervous system.
When we have muscular pain, it is not the muscle cell itself giving off the pain; it is the connective tissue, with its high number of receptors. Pain is a sensory feedback from the somatosensory system. It is a learning process: pain eventually will generate more pain and block motion. Stress and tension will influence the autonomous nervous system and cannot be released without motion. When the fascia is in balance it is self-generating and reinforcing itself. If a dog is not able to make various movements, it’s not. That’s why Martin Fischer can’t stress enough the importance of a total and complete spectrum of motion. It will keep your dog balanced and healthy.
© Images, not mentioned under the photo: Prof. Dr. Martin S. Fischer & Karin E. Lilje, Dogs in Motion, VDH, Germany, 2011.