This important article, by veterinarian Nancy Loving, is a must read! Originally posted in the Horse magazine.
Bone was once considered an inert material with its structure defined by genetics. But it turns out there’s a lot more at work, explained Larry Bramlage, DVM, MS, Dipl. ACVS: “Selective breeding dictates the initial skeleton, but adaptive training in response to exercise modifies it further.” He and other racehorse surgeons are striving to better understand the balance between tolerable and excessive damage—the adaptive kind that occurs naturally and the type that sidelines animals or ends their careers.
During his presentation at the 2013 American Association of Equine Practitioners’ Convention, held Dec. 7-11 in Nashville, Tenn., Bramlage, of Rood & Riddle Equine Hospital, in Lexington, Ky., explained that bone is the only tissue capable of entirely reconstituting itself. With this capacity to change, he noted, there are several ways long bones strengthen themselves in response to training, including modeling and remodeling. Modeling is the process in which bone adds to itself, both inside and out, while remodeling is how existing bone tissue alters itself.
Bramlage started by describing the dynamic nature of bone activity on a cellular level. Two types of bone cells are involved in bone modeling and remodeling: osteoblasts and osteoclasts. Osteoblasts become trapped in the bone and become osteocytes, which are key to sensing biomechanical loads on the skeleton during exercise and directing bone tissue response accordingly. As they detect mechanical loads, they prompt additions to (formation) or reductions in (dissolution) bone mass, to achieve correct bone density for current athletic demands. Osteoclasts then tunnel through and cut canals into the bone, with osteoblasts following to make new bone. Continue reading
©2005 By Deb Bennett, Ph.D.
TIMING AND RATE OF SKELETAL MATURATION IN HORSES,
All Horses of All Breeds Mature Skeletally at the Same Rate
There is no such thing as an ‘early maturing’ or ‘slow maturing’ 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 “early maturing” breed – and neither is the Arabian a “slow maturing” 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 “mature” and (2) what I mean by “starting”.
When is a Horse Skeletally Mature?
Just about everybody has heard of the horse’s “growth plates”, and commonly when I ask them, people tell me that the “growth plates” are somewhere around the horse’s knees (actually the ones people mean are located at the bottom of the radius-ulna bone just above the knee). This is what gives rise to the saying that, before riding the horse, it’s best to wait “until his knees close” (i.e., until the growth plates convert from cartilage to bone, fusing the epiphysis or bone-end to the diaphysis or bone-shaft). What people often don’t realize is that there is a “growth plate” on either end of every bone behind the skull, and in the case of some bones (like the pelvis, which has many “corners”) there are multiple growth plates.
So do you then have to wait until all these growth plates convert to bone? No. But the longer you wait, the safer you’ll be. Owners and trainers need to realize there’s a definite, easy-to-remember schedule of fusion – 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 – the Quarter Horse is the premier among these – 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.
It’s a little hard to see, but this diagram shows how the skeleton of a horse matures.
The fascial system connects each muscle fiber to another. Every muscle is connected to other muscles through the fascia. Muscles are connected to bone, and skin is attached to muscle through the fascia. It is every where! An injury in one area can create stress in a far away part of the body because of the network of fascia, or connective tissue.
There are several ways to deal with myofascial contraction. I try one, and if there is not a noticeable change, I move on to the next. Massage is a creative endeavor which requires knowledge, sharp eyes, and instinct. It is imperative to tune in to the feelings of tension and subsequent looseness when the release works. I have been lucky enough to have learned from some very expressive horses who let me know when I’m on the right track.
Did you know that the skull of a newborn foal is made up of 34 bones connected by cartilage? And that it takes 8 years for the skull to solidify and become unyielding? Until then many of the bones are only loosely connected.