To protect the brain yet allow room for growth, a new-born childâs skull is formed of several bony plates, linked by more flexible seams, or sutures, which harden and fuse together around two years of age. In some rare conditions such as Carpenter syndrome, this process goes awry and the skull fuses too early in development, a problem known as craniosynostosis, leading to an abnormal skull shape. Carpenter syndrome is a genetic condition, also characterised by defects in the development of fingers and toes, with most cases linked to mutations in the gene RAB23. A small signalling protein, RAB23 is involved in many processes during development, but researchers are seeking to elucidate its dramatic effect on skull fusion. By studying sutures in mice lacking RAB23 (pictured, with bone-producing osteoblasts in green), they recently identified roles for RAB23 in regulating important signalling pathways controlling skull development, suggesting new avenues to explore.
Written by Emmanuelle Briolat
Image from work by Md Rakibul Hasan and colleagues
Craniofacial Development and Malformations research group, Orthodontics, Oral and Maxillofacial Diseases, University of Helsinki, Helsinki, Finland
Image originally published with a Creative Commons Attribution 4.0 International (CC BY 4.0)
Published in eLife, July 2020
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**Major Bones & Their Development** Intramembranous Ossification * Cranial Vault * Maxilla/Mandible * Clavicles Consider that the skull bones must ossify prior to delivery of the fetus, so the brain isn't squashed during childbirth to help u
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@quarterlypony I saw this and wanted to share it with some actual facts from veterinarians who disagree with horses being ridden at 2. This might get long, depending on how far I go.. Also for my followers who donât know much about how bad it is to ride a young horse, this is for you too!
Some of these articles may have different opinions on when a horse matures, but all go in depth on skeletal development. Iâm going to go ahead and say I looked everywhere for a solid argument on why it was bad to start horses older and I found none whatsoever, the only things I could find were how younger horses were more adapted to riding because they were forced to remodel their bones to adapt to the workload. No articles I found said anything about higher risk of injuries on an older horse, or the cons of it. Just younger horses.
When is a Horse Skeletally Mature?
âThere is no such thing as an âearly maturingâ or âslow maturingâ breed of horse. Let me repeat that: no horse on earth, of any breed, at any time, is or has ever been mature before the age of six (plus or minus six months). So, for example, the Quarter Horse is not an âearly maturingâ breed â and neither is the Arabian a âslow maturingâ breed. As far as their skeletons go, they are the same. This information comes, I know, as a shock to many people who think starting their colt or filly under saddle at age two is what they ought to be doing. This begs discussion of (1) what I mean by âmatureâ and (2) what I mean by âstartingâ.
âThe longer you wait, the safer youâll be. Owners and trainers need to realize thereâs a definite, easy-to-remember schedule of fusion â and then make their decision as to when to ride the horse based on that rather than on the external appearance of the horse. For there are some breeds of horse â the Quarter Horse is the premier among these â which have been bred in such a manner as to look mature long before they actually are mature. This puts these horses in jeopardy from people who are either ignorant of the closure schedule, or more interested in their own schedule (for futurities or other competition) than they are in the welfare of the animal.â
The Schedule of Growth-Plate Conversion to Bone
Short pastern â top and bottom between birth and 6 months. Long pastern â top and bottom between 6 months and one year. Cannon bone â top and bottom between 8 months and 1.5 years Small bones of the knee â top and bottom of each, between 1.5 and 2.5 years Bottom of radius-ulna â between 2 and 2.5 years Weight-bearing portion of glenoid notch at top of radius â between 2.5 and 3 years Humerus â top and bottom, between 3 and 3.5 years Scapula â glenoid or bottom (weight-bearing) portion â between 3.5 and 4 years Hindlimb â lower portions same as forelimb Hock â this joint is âlateâ for as low down as it is; growth plates on the tibial and fibular tarsals donât fuse until the animal is four (so the hocks are a known âweak pointâ â even the 18th-century literature warns against driving young horses in plow or other deep or sticky footing, or jumping them up into a heavy load, for danger of spraining their hocks). Tibia â top and bottom, between 3 and 3.5 years Femur â bottom, between 3 and 3.5 years; neck, between 2.5 and 3 years; major and 3rd trochanters, between 2.5 and 3 years Pelvis â growth plates on the points of hip, peak of croup (tubera sacrale), and points of buttock (tuber ischii), between 3 and 4 years.
Lots of other interesting stuff from DOCTOR Deb Bennett in this articleÂ
The potential consequences of starting a horse under saddle too young.
âToday, more and more, the big money futurities for performance horses are for three-year-olds, so in order to be competitive, these horses MUST be started as two-year-olds, and sometimes even when they are long-yearlings (18-24 months old). Because of this, many of these horses end up with bowed tendons, Navicular Syndrome, bone spavins, bone chips, stifle injuries, blown-out hocks, hairline fractures, arthritis, severe back problems, sprained necks and a myriad of other problems and conditions associated with stress and strain to young, developing bodies. Many horses will end up with debilitating problems at only four or five-years-old and already receiving anti-inflammatory medications and/or painkillers on a daily basis in their feed, or in the form of injections. Some older horses, in their teens, will develop problems that can be traced directly back to being started too young and too hard. It will take 10 or so years for the stresses they experienced when younger to appear as problematic
Even at two and a half years old a horse is still just a teenager. Heâs not physically mature, nor will he be completely mature, until heâs at least six. In spite of what many in the horse industry believe, all horses regardless of breed mature skeletally at the same rate. Even the most conscientious of horse owner concentrate their concern on a horseâs developing legs, but growth plates are not just in a horseâs knee. There is a growth plate on either end of every bone starting behind the skull, and continuing throughout the remaining skeletal areas. In the case of some bones like the pelvis there are multiple growth plates. Taking the age of final maturity which ranges between 4 â 6 years of age into consideration, as well as the rate of bone fusion in the growth plates, ideally a horse shouldnât be ridden and worked regularly until the minimal age of four. â
The Significance of Too Much Too Soon.
When trying to explain the justification and common sense of waiting until at least 3 years of age to introduce a horse to light work under saddle and incrementally increasing that workload over the next year to a competitive/ performance level by age four, I am almost always inevitably confronted with an impatient disapproving owners condescending response in notifying me that race horses have been started early for centuries and are already often competing at age two.Â
All above information came from hereÂ
Musculo-skeletal unsoundness, particularly related to bone failure and joint injury in racing, equestrian and other athletic horses, can be linked to overloading of bone structures relative to the body weight of the horse, the age at which the young horse is first worked, the speed of exercise and degree by which the bone and joint structures are able to adapt over time to additional body weight and loading forces (Ireland, 1998; Davies, 2001). After each period of exercise, even in growing horses, the bones remodel or react to increase strength, circumference and mineral density (collectively called bone mass) while internal trabecular structures adapt to withstand the increased loading forces. This is a relatively slow process, which can take up to four months to complete in a progressive remodeling process in the young horse exercising during the growth phase or in athletic training before maturity (Lawrence, 2003b).
Bone adaptation to exercise
One of the earliest studies in America on Thoroughbred and Quarterhorse weanlings concluded that bone strengthens by increasing its mineral density, principally by depositing calcium within bones (Raub et al., 1989). These researchers found that over an 111-day period the cannon bones of weanlings exercised by trotting, initially over 400 meters and increasing to over 4 km per day, accumulated 25% more bone calcium than weanlings that had been stalled overnight and turned out into pens during the day.
Numerous other studies, cited by Jeffcott (2001), Firth (2003a) and Lawrence (2003b) in a review of osteochondrosis and response to exercise in horses, have reported similar adaptive responses in foals and weanlings up to five months of age, with a lower bone density in the cortical shaft and subchondral bone mass in non-exercised compared to exercised young horses. After six months of identical exercise, the young horses in the original non-exercised group remodeled the bone, in this case the stifle joint, to establish an equal mineral density and cross-sectional area (Lawrence, 2003b).
(NOTE= Exercise =/= riding, as stated the horses can be lunged or exercised in hand)
It is important that young growing horses have access to free paddock exercise to encourage the formation of sound cartilage and subchondral bone, while over-exercise and excessive weight loading in heavy weight young horses can result in damage to the developing joint cartilage and subchondral bone in joints (Firth, 2003a).
Jeffcott (2001) and Firth (2003a) concluded that the effects of high energy:nutrient ratios, confinement to small yards and over-exercise or lack of adequate exercise, high weight loading and inadequate trace minerals and calcium balance, all adversely influence the cartilage development, bone mineralisation and maturation of the skeleton in the formative years of a horseâs life.
Avoid tight circle tracks
Do not gallop young horses around tight, compacted curves or end circles on the track too early in their training preparation. Gallop only up straights initially, then work progressively faster into corners and around end circles to allow adaptation to the centrifugal sideways strain forces, starting after 6-8 weeks of training. Avoid sudden introduction to fast work and limit speed of galloping around unbanked, relatively tight bends initially, especially on dry, compacted tracks. (AKA donât barrel race 2 year olds!)
Conclusion
The soundness of the skeletal structure in growing and exercising horses is largely dependent on providing an adequate diet with a balanced intake of bone and joint structural nutrients during the formative years of a horseâs life. Controlled exercise will assist in the skeletal development and allow remodeling in response to loading in both growing and exercising horses.
Care when formulating feeds, premixes and supplements to ensure optimum bioavailability and stability of skeletal nutrients is essential to maintain long term athletic soundness in all classes of horses.
Came from this articleÂ
References
Bailey, C.J. 1998. Wastage in the Australian thoroughbred racing industry. RIRDC Research Paper No. 98/52. Rural Industries Research and Development Corporation, Canberra, Australia pp. 16â17.
Baker, L.A. 2002. The effect of inorganic and organic forms of copper and zinc on mineral digestibility and retention in yearling geldings in training. In: Nutritional Biotechnology in the Feed and Food Industries, Proc. of Alltech 18th Annual Symposium. Nottingham University Press, UK pp. 332-338.
Boemo, C.M. 1998. Injuries of the metacarpus and metatarsus. In: Canine Sports Medicine and Surgery. (Bloomberg, Dee and Taylor, eds). Saunders. pp 150â157.
Boston, R.C. and D.M. Nunamaker. 2000. Gait and speed as exercise components of risk factors associated with onset of fatigue injury of the third metacarpal bone in two year old thoroughbred racehorses. American J. Vet. Res. 61: 6102-604.
Davies, H.M.S. 2001. The relationship between surface strain and measurements of bone quality, quantity and shape. Proc. 4th Int. Workshop. Anim. Locomotion (1WAL2000) Vienna 22-28 May, 2001. Equine Vet. J. 33:16â20.
Davies, H.M.S. 2003. The prediction and prevention of musculoskeletal injury using radiographic measurement of bone shape in thoroughbred racehorses during training. Aust. Equine Veterinarian 22(2):76-80.
Davies, H.M.S. and R.N. McCarthy. 1994. Strain in the yearling equine metacarpus during locomotion. Equine Vet. J. 17:25.
Dunnet, C.E. 2003. Antioxidants in physiology and nutrition of exercising horses. In: Nutritional Biotechnology in the Feed and Food Industries, Proc. of Alltech 19th Annual Symposium. Nottingham University Press, UK pp. 344.
Firth, E.C. 2003a. Recent advances in osteochondrosis research. In: Proc. 2003 Equine Nutrition Conference. Growth and Development of the Equine Skeleton. Kentucky Equine Research, Sydney, Australia pp. 95-101.
Firth, E.C. 2003b. Methods of assessing bone growth and development in young horses. In: Proc. 2003 Equine Nutrition Conference. Growth and Development of the Equine Skeleton. Kentucky Equine Research, Sydney, Australia pp. 175-190.
Ireland, B.W. 1998. Race track biomechanics and design. In: Canine Sports Medicine and Surgery. (Bloomberg, Dee and Taylor, eds). W.B. Saunders pp. 391â396.
Jeffcott, L. 2001. Osteochondrosis in young horses â a major industry problem. International Horse Industry Symposium Proc 342 Post. Grad. Foundation In Vet. Science, University of Sydney, 4-6 July 2001, Sydney pp. 325-334.
Kohnke, J.R., 2002. Integration of nutrition and health: implications for equine performance. In: Nutritional Biotechnology in the Feed and Food Industries, Proc. of Alltech 18th Annual Symposium. Nottingham University Press, UK pp. 343-349.
Lawrence, L.A. 2003a. Principals of bone development in horses. In: Proc. 2003 Equine Nutrition Conference. Growth and Development of the Equine Skeleton. Kentucky Equine Research, Sydney, Australia pp. 69-73.
Lawrence, L.A. 2003b. Effects of exercise and training on skeletal development in horses. In: Proc. 2003 Equine Nutrition Conference. Growth and Development of the Equine Skeleton. Kentucky Equine Research, Sydney, Australia pp. 210-217.
Nunamaker, D.M., C.M. Butterweck and M.T. Provost. 1990. Fatigue fractures in thoroughbred racehorses. Relationship with age, peak bone strain and training. J. Orthopedic Res. 8:604-605.
Raub, R.H., S.G. Jackson and J.P. Baker. 1989. The effect of exercise on bone growth and development in weanling horses. J. Anim. Sci. 67:2508.
To construct a building from scratch, you might first build a basic shell or scaffold, then replace that with the permanent structure. Building new bone is similar. An intermediate cartilage structure is established first, only to be converted to solid bone subsequently. This process is supported by a dense network of blood vessels, but exactly how they help is unclear. A new study has found that a particular type of these vessels, known as type H (yellow in the bone section pictured, with vessels stained green and red), help replace the cartilage when itâs time. Specifically, the vessels steer bone growth direction, and endothelial cells lining them lead the cartilage breakdown. Excessive cartilage damage is a hallmark of arthritis, and improving bone repair would benefit countless injured patients, so the next step is asking whether we can control and harness this important function of blood vessels.
Written by Anthony Lewis
Image from work by Sara G. Romeo and colleagues
MRC London Institute of Medical Sciences, London, UK
Image copyright held by the original authors
Research published in Nature Cell Biology, April 2019
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Starting with the right nutrition from a trusted retail feed store in Visalia, California, sets the foundation.
Ensuring young animals develop strong bones is crucial for their long-term health and vitality. Starting with the right nutrition from a trusted retail feed store in Visalia, California, sets the foundation. These stores offer a variety of feeds formulated with essential nutrients like calcium, phosphorus, and vitamin D, which are vital for bone development in young animals.
Cowâs milk has been a daily staple for many people for millennia. While milk is a popular food, new research suggests it may be damaging to the body. However, other evidence indicates that dairy has health benefits.
So, what really is the truth? Continue reading to learn about the benefits and drawbacks of milk, as well as some alternatives to consider if you canât tolerate milk or choose not toâŚ