Brumbies, or the feral horses in Australia, came over in the ‘first fleet’ and by the 1880’s occurred in most areas of Australia. Established and thriving in the environment, there are now 1.2 million brumbies with the only true limiting factor to the population being drought, and culling. In very recent years the population has increased due to good rainfall with numbers rising above the normal “20% rule”. These are horses that have bred to survive, with over 250 years of natural selection producing strong horses capable of withstanding extreme environmental conditions. Early breed influences include the arab and the thoroughbred but later imported ponies, saddle draught and harness horses all had an impact. Early studies concluded that brumbies are not genetically different to the domestic horse which was important to establish before more detailed investigations took place.
Brian talked about the 6 main areas of study, 5 in Australia and 1 in New Zealand. These areas varied from alpine mountain to sandy desert; hard substrate to soft substrate, rocky to smooth, flat to mountainous, plentiful lush grazing to sparse tough forage, frequent water sources to intermittent watering holes miles apart.
The GPS tracking gave vital data to the movements of these horses in these different areas. A ‘low’ distance covered per day was less than 5 kilometres, moderate 5 to 10 kilometres and high more than 10 kilometres. Feeding grounds and watering locations had a direct impact on these distances travelled. Subsequent work indicated that a 40 acre field is considered to be the optimal size for maximum movement in domestic horses. Furthermore a study of mares and foals showed that at 3 days old a foal’s movement was similar to the mares, between 3 to 5 weeks the mare moved more than the foal but the foal’s movements were faster and considered to be important for development. Therefore it would be fair to suggest that ‘boxing up foals’ in early weeks is not recommended and the management of our domestic youngstock needs further consideration.
The effects of low mileage or, ‘limited exercise’ are well documented and can be readily seen in both the feral and domestic horses. Overweight horses are insulin resistant and at risk of, if not victim of, laminitis.
Brian’s more recent research has concentrated on the palmar foot and sole and their role in the absorption of concussion and support. Frequently Brumby’s showed some calcification (no longer flexible or with a good blood supply), more often on the lateral side indicating landing laterally (but mainly loading centrally). Measurements of the soft tissue volume in the palmar foot demonstrated that the horse’s foot is not symmetrical and therefore should not be treated as such. The medial and lateral side operate differently. A comparison of the soft tissue volume with other research indicated that the Brumby’s have a 12.5% bigger digital cushion – a reflection of the mileage and substrate covered. Sole depth changed throughout the foot – more on the inside and outside, less in the centre and less in between - and was thicker overall in horses from hard substrate.
The measurement of sole depth in the live horse is one subjected to a number of methods; collateral groove depth, ‘cup’ depth and sole hardness to name a few. Measurements taken before and after dissection indicated that groove depth at the heels gave a reasonably good correlation and this was applicable in both feral and domestic horses.
Within the 6 main study areas, 6 different foot types were not
ed however some commonalities that may be important included the angle of the coronary band at 20 degrees (compared with Strasser’s measurement of 30 degrees) and the medial and lateral wall angles are very similar (no significant different between the left and the right foot therefore is domestication an important influence?).
Horses were also taken from one study area to another – a swap in environment. 4 months later, 1000km travelled later and the horses that were moved from soft to hard substrate (good nutrition to poor nutrition) doubled their hoof wall growth. Those that were moved from hard to soft reduced their growth rate. There were no significant genetic differences on the horses but the substrate hardness (and abrasiveness) in addition to the distance travelled accounted for the differences noted.
The Square Toe
Throughout Brian’s research square toes were evident in a number of scenarios. For example - in young stallions travelling particularly large distances (confirmed by GPS) looking for mares; in an area of sand dunes horses drag toes and dig for water; and in an area where water sources are occupied by crocodiles, horses dig for water back from the water’s edge for safety. These apparent ‘reasons’ for the appearance of a squared off toe was deemed to be unnatural and not part of the ‘normal horses foot shape’.
The hoof wall is thicker at the toe and thins out to the heel quarter. The heel quarters need flexibility and this is also reflected in the lamellar pattern. The tubules on the outside of the hoof wall are weight bearing and appear to change according to the environment. The feral horse has the same rate of wear as growth.
Brian’s studies have shown that the wild horse foot is not pathology free in fact quite the opposite. Studies have found laminitis, flares, calcification, hoof wall cracks and splits to name but a few. Of particular interest is that no laminitis was found in the desert areas but this was also the area of increased hoof wall depth; coronary stretching and lamellar strengthening. Calcified lateral cartilage was found in those horses on rocky substrate travelling greater distances and the comparisons continue in relation to the different environments.
Interestingly an examination into hoof moisture content in 3 different environments revealed that each had the same hoof moisture content as each other at approximately 30% - the hoof gets it’s moisture from the inside not the outside. The outside periople of the hoof is more or less waterproof. A comparison of ‘soaked sole’ to ‘unsoaked sole’ revealed more of a difference in the ability to absorb moisture from the environment when in contact with the ground compared to the hoof wall. Most of the work farriers do is in the first few millimetres from the ground which may require further consideration.
From the work that Brian and his team have done what we can we apply to domestic foot care? The horses foot has been considered as an adaptation to the environment, it is not, it is a consequence of the environment. ‘Natural’ is not necessarily normal nor is the horse stuck with the foot that he or she is born with. In the simplest form, the ‘take home message’ was not to over trim. We know that the hoof wall is thicker at the toe than at the heel and the toe has an increased wear rate. We know that the foot is less rigid at the back to allow for movement yet more rigid at the front to give support to the structure. The foot should be trimmed on its merits. Moving forward, Brian recognises that further work is needed now in the application of these findings in the complex environments in which the domestic horse exists to improve foot health and care.
This presentation was both thought provoking and interesting gaining more than a few questions and instigating discussions from the floor! The scale of this research backed up by hard scientific methods makes the findings very difficult to ignore. Brian and his team are unbelievably dedicated and we all should hope that the research continues for years to come as we all have a lot to gain from it. Brian has a practical and realistic approach to the horse along with a natural understanding and appreciation of the environment and we thank him for sharing his incredible work with us. For those wishing to read more please visit the ABRU website www.wildhorseresearch.com
Special thanks also to Mark Caldwell FWCF for providing an interesting introduction to the work that he and his team are carrying out at Myerscough into the hoof capsule proportions as a model for dynamic equilibrium.
Yet another successful clinic; educational and inspiring. Billy and Lucy Crothers would like to thank everyone who attended over the weekend and to the staff at Handmade Shoes for their hard work in the run up to, during, and after the clinic. The autumn clinic with Dave Duckett is pencilled in the diary for October; we hope to see you there!