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WHAT IS BONE?
Bone is a dynamic tissue matrix of collagen and minerals and consists of about 50% water. It exists in a constant state of flux or remodelling, in which bone – destroying cells (osteoclasts) cause the breakdown (resorption) of bone, while bone – forming cells (osteoblasts) cause bone synthesis. Calcium availability significantly affects the dynamics of bone remodelling.
Bone is a constantly changing tissue with fluctuating demands for calcium replenishment. However, calcium is also important for many other metabolic functions.
Many of us are guilty of thinking of our greyhounds’ bones in terms of having been formed and set up for life before the dog ever reached the track.
This is far from the case as the bones like every other part of the body are continually being rebuilt. The nutrition received from 0 to 18 months is vital but it does not stop there.
Bone remodelling is the ability of bone to thicken and gain strength when regularly placed under stress. The stress of going around bends – always in the same direction – is probably the most important stress that the racing greyhound has to encounter.
It is a reversible state with changes detectable within weeks, not months.
Many leading greyhound veterinarians now consider that efficient bone re-modelling can have a highly significant role in injury prevention. The vital point to consider is this: if, at key stages in the strengthening of bones, there is a delay in the supply chain of vital nutrients, the consequences could prove significant.
1) Significant numbers of serious bone injuries are caused by micro damage accumulation
2) To maintain optimum condition, bone and cartilage requires a carefully balanced intake of vitamins, minerals and proteins.
There is negligible specific research demonstrating that inadequate nutrition plays a significant role in causing serious injury in the racing greyhound. However, we believe that the combination of these two irrefutable scientific facts, can only lead to one conclusion.
POINT 1: Most Bone Injuries Don’t ‘Just Happen’
Modern research is confirming what greyhound trainers have known for a long time; that greyhounds are particularly prone to certain forms of bone fracture. In the scientific journal ‘Calcified Tissue International’, a team of scientists recently looked into the greyhound injury situation.
They did so not because they were particularly interested in greyhounds and their injuries but because they view the racing greyhound as a good research and investigation model of what is happening with short distance running athletes. They are a good study model for investigating fatigue fracture and adaptation of foot bones subjected to cyclic loading.
The researchers (Tomlin, Lawes, Blunn, Goodship and Muir) found greyhounds to have a high incidence of certain types of bone fracture that are not associated with overt trauma. The scientists speculated that these types of injuries were occurring because of an accumulation of fatigue micro-damage. They further postulated that bone from racing dogs would show site-specific microdamage accumulation, causing predisposition to structural failure.
Subsequent examination of greyhound injuries showed their postulations to be correct – that these types of injuries don’t just suddenly happen, they are the result of progressive accumulation and coalescence of branching arrays of fatigue micro-cracks, the formation of which appears to be predisposed to adapted bone.
Greyhound trainers and vets are fully familiar with the fact that a greater percentage of these types of injuries occur to the dog’s right side limbs. This is because these limbs are subject to asymmetric cyclic compressive loading. This induces site-specific bone adaptation. These bones are the ones that appear to be predisposed to injury.
This research is of great interest to anyone involved in greyhound racing.
It is now understood that the rest periods between circular runs are extremely important for allowing micro-cracks to heal. This means that many of the old hands at the game are spot on with their insistence on giving dogs long breaks between circular runs at the schooling stage in particular. It also means that seasonal breaks from racing are a very good idea.
POINT 2: Optimum bone health demands correct nutrition
The scientific study that has gone into examining the relationship between nutrition and bone health is staggering – thousands of studies – millions of words. Our knowledge is being extended virtually on a weekly basis.
In the medical journal ‘Current Opinion on Clinical Nutrition and Metabolic Care’ in July 2005, the authors Cederholm and Hedstrom reviewed the current research into nutritional aspects of bone injury treatment and concluded that the correct nutrient supply is of vital importance to the bone repair process.
Experts in this field point to the importance of a correct supply of Calcium, Vitamin D, Vitamin K, Boron, Zinc, Magnesium, Copper and Manganese. (Australian Formula contains all these plus chrondroitin sulphates and other vitamins and minerals that are required in trace amounts.)
In the Journal of Sports Science and Medicine, numerous authors, including Wohl et al 2000, stressed the importance of dietary factors in maintaining bone health, in particular the importance of a correct calcium supply and adequate protein in the repair process associated with bone remodelling which is a potent example of tissue repair requiring the correct nutrient flow that can only be derived from optimum nutrition.
A Brazilian study into low protein levels concluded “The low protein diet resulted in significantly lower tensile strength and stiffness of calluses compared to the other three dietary regimens, this despite adequate caloric intake. In addition, the low protein diet resulted in a callus with ‘rubbery’ mechanical properties compared to the “rigid” calluses of the other three groups”
Anybody wishing to read this type of information can readily obtain the data with an internet search. However, we understand that most greyhound trainers have neither the time nor patience to embark on such a mammoth trawl. So we have therefore tried to summarise the most important facts into a series of myth busting statements:
The myths:
1) ‘Bone health doesn’t concern adult greyhounds.’ This is the first and most serious error of judgement. It is a commonly held belief that correct nutrition is only important to pups and saplings. In reality, a greyhound’s skeleton is a live, constantly changing structure that needs on-going replenishment of vital nutrients.
2) ‘Calcium is the only nutrient that bones require.’ Another major error. Many people assume that if you get enough calcium into the dog, even with added vitamin D, then you will build and keep a good skeletal system. Sadly it is not that simple. Firstly you need a mesh for the micro fibres to cling onto. This mesh is called the osteoid and is made up of proteins, collagen, elastin and various glucosamine polymers. To build these proteins, the dog also needs vitamin C, vitamin B6, copper and zinc. To make glucosamine polymers the dog needs glucosamine and manganese. To activate the whole matrix you need vitamin K.
3) ‘A feed must contain all the important nutrients or they wouldn’t be allowed to sell it.’ Yes, we’ve heard that one! Sadly the law relating to the sale of animal feeds just isn’t that strict. If it were, there would be a lot less cheap foods on the market. Sure, vitamins are comparatively cheap, even if their quality is low and there is reduced bio-availability to the dog. Quality fats are not cheap and they are vital in the transportation and absorption of vitamins. High quality minerals and supplements don’t come cheap either.
But then, neither do good greyhounds or vets bills!
