Image FR : Chevaux ES : Caballos The horse is a hoofed mammal, one of eight living species of the family Equidae. The horse has evolved over the past 45 to 55 million years from a small multi-toed creature into the large, single-toed herbivore of today. Humans began to domesticate horses around 4500 BC, and their domestication is believed to have been widespread by 3000 BC; by 2000 BC the use of domesticated horses had spread throughout the Eurasian continent. Although most horses today are domesticated, there are still endangered populations of the Przewalski's Horse, the only remaining true wild horse, as well as more common feral horses which live in the wild but are descended from domesticated ancestors. There is an extensive, specialized vocabulary used to describe equine-related concepts, covering everything from anatomy to life stages, size, colors, markings, breeds, locomotion, and behavior. Horses are anatomically designed to use speed to escape predators, and have a well-developed sense of balance and a strong fight-or-flight instinct.

Related to this need to flee from predators in the wild is an unusual trait: horses are able to sleep both standing up and laying down. Female horses, called mares, carry their young for approximately 11 months, and a young horse, called a foal, can stand and run shortly following birth. Most horses begin training under saddle or in harness between the ages of two and four. They reach full adult development by age five, and have an average lifespan of between 25 and 30 years. Horses and humans interact in many ways, not only in a wide variety of sport competitions and non-competitive recreational pursuits, but also in working activities including police work, agriculture, entertainment, assisted learning and therapy. Horses were historically used in warfare. A wide variety of riding and driving techniques have been developed, using many different styles of equipment and methods of control. Many products are derived from horses, including meat, milk, hide, hair, bone, and pharmaceuticals extracted from the urine of pregnant mares. Humans provide domesticated horses with food, water and shelter, as well as attention from specialists such as veterinarians and farriers.

Horse breeds are loosely divided into three categories based on general temperament: spirited "hot bloods" with speed and endurance; "cold bloods," such as draft horses and some ponies, suitable for slow, heavy work; and "warmbloods," developed from crosses between hot bloods and cold bloods, often focusing on creating breeds for specific riding purposes, particularly in Europe. There are over 300 breeds of horses in the world today, developed for many different uses. The English-speaking world measures the height of horses in hands, abbreviated "h" or "hh," for "hands high," measured at the highest point of an animal's withers, where the neck meets the back, chosen as a stable point of the anatomy, unlike the head or neck, which move up and down. One hand is 4 inches (10 cm). Intermediate heights are defined by hands and inches, rounding to the lower measurement in hands, followed by a decimal point and the number of additional inches between 1 and 3. Thus a horse described as "15.2 h," is 15 hands, 2 inches, or 62 inches (160 cm) in height.

The size of horses varies by breed, but can also be influenced by nutrition. The general rule for cutoff in height between what is considered a horse and a pony at maturity is 14.2 hands (58 inches (150 cm)). An animal 14.2h or over is usually considered a horse and one less than 14.2h as a pony. However, there are exceptions to the general rule. Some breeds which typically produce individuals both under and over 14.2h are considered "horses" regardless of height. Conversely, some pony breeds may have features in common with horses, and individual animals may occasionally mature at over 14.2h, but are still considered to be ponies. The difference between a horse and pony is not simply a height difference, but includes other aspects of phenotype or appearance. There are noticeable differences in conformation and temperament. Ponies often exhibit thicker manes, tails and overall coat. They also have proportionally shorter legs, wider barrels, heavier bone, shorter and thicker necks, and short heads with broad foreheads.

They often have calmer temperaments than horses and also a high level of equine intelligence that may or may not be used to cooperate with human handlers. In fact, small size, by itself, is sometimes not a factor at all. While the Shetland pony stands on average 10 hands high (40 inches (100 cm)), the Falabella and other miniature horses, which can be no taller than 30 inches (76 cm), the size of a medium-sized dog, are classified by their respective registries as very small horses rather than as ponies. Horses exhibit a diverse array of coat colors and distinctive markings, described with a specialized vocabulary. Often, a horse is classified first by its coat color, before breed or sex. Flashy or unusual colors are sometimes very popular, as are horses with particularly attractive markings. Horses of the same color may be distinguished from one another by their markings. The genetics that create many horse coat colors have been identified, although research continues on specific genes and mutations that result in specific color traits.

Essentially, all horse colors begin with a genetic base of "red" (chestnut) or "black," with the addition of alleles for spotting, graying, suppression or dilution of color, or other effects acting upon the base colors to create the dozens of possible coat colors found in horses. Horses which are light in color are often misnamed as being "white" horses. A horse that looks pure white is, in most cases, actually a middle-aged or older gray. Grays have black skin underneath their white hair coat (with the exception of small amounts of pink skin under white markings). The only horses properly called white are those with pink skin under a white hair coat, a fairly rare occurrence. There are no truly albino horses, with pink skin and red eyes, as albinism is a lethal condition in horses. Pregnancy lasts for approximately 335340 days and usually results in one foal. Twins are very rare. Colts are carried on average about 4 days longer than fillies. Horses are a precocial species, and foals are capable of standing and running within a short time following birth.

Horses, particularly colts, may sometimes be physically capable of reproduction at about 18 months. In practice, individuals are rarely allowed to breed before the age of three, especially females. Horses four years old are considered mature, although the skeleton normally continues to develop until the age of six; the precise time of completion of development also depends on the horse's size, breed, gender, and the quality of care provided by its owner. Also, if the horse is larger, its bones are larger; therefore, not only do the bones take longer to actually form bone tissue, but the epiphyseal plates are also larger and take longer to convert from cartilage to bone. These plates convert after the other parts of the bones, but are crucial to development. Depending on maturity, breed, and the tasks expected, young horses are usually put under saddle and trained to be ridden between the ages of two and four. Although Thoroughbred race horses are put on the track at as young as two years old in some countries, horses specifically bred for sports such as dressage are generally not entered into top-level competition until they are a minimum of four years old, because their bones and muscles are not solidly developed, nor is their advanced training complete.

For endurance riding competition, horses are not deemed mature enough to compete until they are a full 60 calendar months (5 years) old Fetlock - definition of fetlock by The Free Dictionary Fetlock - definition of fetlock by The Free Dictionary Related to fetlock: fetlock joint fet·lock n. 1. a. A projection on the lower part of the leg of a horse or related animal, above and behind the hoof. b. A tuft of hair on such a projection. 2. The joint marked by such a projection. [Middle English fitlok; see ped- in the Appendix of Indo-European roots.] fetlock fetterlock n 1. (Zoology) a projection behind and above a horse's hoof: the part of the leg between the cannon bone and the pastern 2. (Zoology) Also called: fetlock joint the joint at this part of the leg 3. (Zoology) the tuft of hair growing from this part [C14 fetlak; related to Middle High German vizzeloch fetlock, from vizzel pastern + -och; see foot] fet•lock (ˈfɛtˌlɒk) n. 1.

the projection of the leg of a horse behind the joint between the cannon bone and great pastern bone, bearing a tuft of hair. 2. the tuft of hair itself. 3. Also called fet′lock joint`. the joint at this point. [1275–1325; Middle English fitlok, akin to Middle High German viz(ze)loch, ultimately derivative of Germanic *fet-, a gradational variant of *fot- foot ] ThesaurusAntonymsRelated WordsSynonymsLegend: fetlock joint horse's foot - the hoof of a horse articulatio , joint , articulation - (anatomy) the point of connection between two bones or elements of a skeleton (especially if it allows motion) 2. fetlock - projection behind and above a horse's hoof horse's foot - the hoof of a horse appendage , outgrowth , process - a natural prolongation or projection from a part of an organism either animal or plant; "a bony process" Translations 1. (Zool) (= joint) → espolón m 2.

(= hair) → cernejas fpl n → Fessel f; (joint) → Fesselgelenk nt fetlock Want to thank TFD for its existence? Tell a friend about us , add a link to this page, or visit the webmaster's page for free fun content . Link to this page: hoofed mammal References in classic literature ?

Pickwick, Sir:- I address you upon the subject of sin the sinner I mean is a man named Winkle who makes trouble in his club by laughing and sometimes won't write his piece in this fine paper I hope you will pardon his badness and let him send a French fable because he can't write out of his head as he has so many lessons to do and no brains in future I will try to take time by the fetlock and prepare some work which will be all commy la fo that means all right I am in haste as it is nearly school time View in context They found the prairies saturated with the heavy cold rains, prevalent in certain seasons of the year in this part of the country, the wagon wheels sank deep in the mire, the horses were often to the fetlock, and both steed and rider were completely jaded by the evening of the 12th, when they reached the Kansas River; a fine stream about three hundred yards wide, entering the Missouri from the south.

View in context Horrock, at a question from Fred about his horse's fetlock, turned sideways in his saddle, and watched the horse's action for the space of three minutes, then turned forward, twitched his own bridle, and remained silent with a profile neither more nor less sceptical than it had been. cannon bone - Memidex dictionary/thesaurus cannon bone Definition: a greatly developed metatarsal or metacarpal bone in the shank or cannon part of the leg in hoofed mammals Class: Wikipedia: Limbs of the horse structures made of dozens of bones, joints, muscles, tendons and ligaments that support the weight of the equine body. They include two apparatuses: the suspensory apparatus, which carries much of the weight, prevents overextension of the joint and ...

Collins Dictionary: cannon bone a bone in the legs of horses and other hoofed animals consisting of greatly elongated fused metatarsals or metacarpals (19 of 373 words, 4 usage examples) Merriam-Webster: cannon bone a bone in hoofed mammals that extends from the knee or hock to the fetlock ; especially, the enlarged metacarpal or metatarsal of the third digit of a ... (28 of 47 words) Oxford Dictionary: cannon bone a long tube-shaped bone in the lower leg of a horse or other large quadruped, between the fetlock and the knee or hock (23 of 43 words) American Heritage Dictionary: cannon bone A supporting bone of the leg in some hoofed mammals, analogous to the metacarpus of the hand or the metatarsus of the foot in humans. (25 of 28 words) The brain is situated within the cranium - a box-like posterior part of the skull. The brain is connected to the spinal cord through a large hole, the foramen magnum.

The foramen magnum is flanked by two large knobs or occipital condyles that form a joint with the first cervical vertebra of the neck. The skulls of meat animals are damaged in the frontal bone region if animals have been stunned by concussion. Sinuses or spaces are present between the inner and outer cranial walls. Young pig There are considerable differences in the size and shape of the skull in different breeds of farm mammals, particularly in pigs where a long narrow skull is a feature that is often associated with a relatively large amount of fat in the carcass. The major muscles used in chewing are attached to the coronoid process which is a large expansion of the lower jaw or mandible. Mature pig skull showing: C, condyle of mandible; ca, canine teeth; F, frontal bone; i, incisor teeth; M, mandible; mo, molar teeth; MX, maxilla, N, nasal bone; O, occipital bone; P, parietal bone; PM, premaxilla; pmo, premolar teeth; PP, paramastoid process; and Z, zygomatic arch. The coronoid process is located medially to the zygomatic arch, between the eye and the ear.

The coronoid process allows muscle leverage to be exerted onto the mandible. The joint between the skull and the lower jaw is formed by a mandibular condyle. In cattle and sheep, the mandibular condyle is relatively flat and allows considerable movement in a horizontal plane. Lateral movement is important in animals whose teeth work with a grinding action. The jig-saw pattern of suture joints on the skull surface indicates that the whole skull is formed by the fusion of a number of individual bones. A saw cut made transversely through the facial region of the skull reveals delicate rolls of the turbinate bones in the nasal cavity. The turbinate bones support a large area of nasal epithelium to warm and moisten the air travelling to the lungs, and to provide a large area for the sense of smell. Skeleton of the neck Atlas (on left) and axis of sheep. The vertebral column or backbone is the main axis of the skeleton and it protects the spinal cord. The spinal cord is located in a neural canal formed by a long series of neural arches, each contributed by a different vertebra. The neural arch of each vertebra is supported on the body or centrum of the vertebra.

In some types of vertebrae, the neural arch extends dorsally as a prominent spine that may be called a dorsal spine, a neural spine or a spinous process. Where movement between vertebrae is possible, the centra are separated by cartilaginous intervertebral discs. In mammals, the anterior and posterior faces of the centra are almost flat. The names and numbers of the different types of vertebrae in meat animals are variable. NAME--------REGION---------BEEF----------PORK------------LAMB Thoracic-----Ribcage-----------13------------13 to 17-----------13 to 14 Lumbar-------Loin-------------6-------------5 to 7------------6 to 7 Sacral ------Sirloin-------------5-------------4-----------------4 Caudal-------Tail------------18 to 20----------20 to 23----------16 to 18 Meat animals, like most other living mammals, usually have seven cervical vertebrae in the neck region. However, sheep sometimes have only six cervical vertebrae, and as few as five cervical vertebrae have been reported in pigs.

In cattle and sheep, but to a lesser extent in pigs, the neck is very mobile, and the cervical vertebrae have a series of interlocking articular and tranverse processes that limit excessive bending of the neck to protect the spinal cord. The first cervical vertebra, the atlas, articulates with the skull and is greatly modified in shape to form a joint that enables the animal to nod its head up and down. Rotation or twisting of the head occurs from the joint between the atlas and the next cervical vertebra, the axis. The ligamentum nuchae is a very strong elastic ligament in the dorsal midline of the neck, and it relieves the animal of the weight of its head. Were it not for the ligamentum nuchae, the head of the standing animal would droop between its forelimbs. Plan of neck in beef, showing:1, ligamentum nuch; 2, atlas; and 3, axis. The ligamentum nuchae is pale yellow with a thick cord-like or funicular part and a flat sheet-like or lamellar part.

Once the head is removed at slaughter, the elasticity of the ligamentum nuchae causes the neck of the carcass to curve dorsally. Beef and pork carcasses usually are split into right and left sides soon after slaughter and the series of vertebral centra that are now exposed is called the chine bone. Ribcage Sheep The number of vertebrae in pork carcasses is rather variable, particularly in certain breeds. The heritability of the number of vertebrae is about 0.74. Each extra vertebra adds about 15 mm to the length of the carcasses at slaughter weight. The number of thoracic vertebrae, each bearing left and right ribs, ranges from 13 to 17. Breeds with a large size when mature and with heavy bone development tend to have more thoracic vertebrae than lighter breeds. Sometimes the ribs on extra thoracic vertebrae are only partially formed, but usually they are complete. The minimum number of lumbar vertebrae is generally found in cacasses with the maximum number of thoracic vertebrae.

However, the variability of vertebral numbers frequently leads to an increase in the total number of vertebrae, so that the phenomenon is not due simply to the substitution of one type of vertebra for another. Lamb carcasses usually have either 13 or 14 thoracic vertebrae and a corresponding number of pairs of ribs. Experimental studies suggest that the number of vertebrae in an animal is determined by the number of somites that develop along the length of the spinal cord. By definition, in mammals, the vertebrae that bear ribs are identified as thoracic vertebrae. In the embryo there are ossification centers on each side of the developing vertebrae. In vertebrae that do not normally develop ribs, these lateral ossification centers contribute their bone tissue to the centra of adjacent vertebrae. In the thoracic vertebrae, however, this laterally derived bone tissue remains separate from the centra and forms the ribs. Thus, the numbers of pairs of ribs and the numbers of thoracic vertebrae are determined by the developmental mechanism that controls the fate of the tissue which is derived from the lateral ossification centers.

The cage formed by thoracic vertebrae, ribs and sternum is an essential component of the respiratory system. Thoracic vertebrae are distinguished by their tall dorsal spines, many of which point towards the hindquarter and are known as the feather bones. The ribs are joined to the vertebral column dorsally so that the head of each rib articulates with the bodies of two adjacent vertebrae. Rib showing : 1, head; 2, neck; 3, tubercle; and 4, costal cartilage.Each rib has a tubercle that articulates with the transverse process of the more posterior of its two vertebrae. Ventrally, the anterior ribs articulate with the sternum and are termed sternal ribs. The more posterior ribs are called asternal ribs and they only connect to the sternum indirectly via costal cartilages. The most posterior ribs have only small costal cartilages that do not reach all the way to the sternum. Some of the costal cartilages are very hard and may appear more like bones than typical cartilage. The sternum is formed by a number of closely joined bones, the sternebrae.

When split through the midline, the interior structure of the sternebrae resembles that found in the centra of the vertebrae. But in an isolated cut of meat, the distinction between sternebrae and vertebral centra may be made by the presence or absence of a neural canal. A neural canal is seen in the vertebrae of carcasses that have been symmetrically separated into right and left sides. The structure of the ribcage is rather variable in lamb carcasses. Carcasses have been found with as few as 12 ribs on one side, and left and right sides of the ribcage may differ in their number of ribs. In lambs, rib length is determined mainly by age while the plane of nutrition determines rib thickness.

-----------------------BEEF---------PORK------------LAMB Total pairs of ribs-------------13----------13 to 17-----------13 to 14 Pairs of sternal ribs-------------8-----------7-----------------8 Pairs of asternal ribs------------5-----------7 to 8-------------5 to 6 Number of sternebrae-----------7-------------6--------------6 to 7 The skeleton of the loin, sirloin and rump Sheep pelvis In a live animal, the lumbar vertebrae act like a suspension bridge to support the weight of the abdomen. The lumbar vertebrae have flat, wing-like transverse processes that broaden the abdominal cavity dorsally to provide a strong attachment for the muscles of the abdominal wall that carry the weight of the viscera. Plan of kumbar region in hanging beef carcass showing: 1, ilium; 2, sacrum;3, last lumbar vertebra;4, first lumbar vertebra; and 5, last rib. The propulsive thrust generated by the hindlimb during locomotion is transmitted to the sacral vertebrae by the pelvis. To strengthen the sacral vertebrae, they are fused together to form the sacrum.

Plan of the sacral region in a hanging beef carcass showing:1, ischium; 2, femur;3, sacrum; and 4, ilium. Fusion of the sacral vertebrae to form the sacrum is incomplete in young animals and provides an important clue to animal age in the dressed carcass. The pelvis is formed by three bones on each side. The most anterior bone on each side is the ilium. The shaft of the ilium expands anteriorly to form a flat wing attached to the sacrum. This joint is called the slip joint. When seen in a sirloin steak, the ilium may appear either as a small round bone or a large flat bone. The anterior edges of the ilia form the hooks of the live animal. The most posterior bone of the pelvis on each side is the ischium. The pelvis and the sacrum form a ring of bone completed ventrally by the pubes. The left pubis is separated from the right pubis by fibrocartilage which, at parturition, may soften to allow movement between the bones of the pelvis.

The pubes are separated when carcasses are split into left and right sides in the abattoir. Plan of the pelvis in a hanging beef carcass showing:1, lesser sciatic notch; 2, ischiatic spine; 3, greater sciatic notch; 4, psoas tubercle; 5, obturator foramen; 6, symphysis pubis;7, ischium; and 8, ilium. The pubic bone exposed on a carcass is called the aitch bone. The aitch bone is curved in steer and bull carcasses, is moderately curved in heifers, but is straight in cow carcasses. Another plan of the both sides of the pelvis in a hanging carcass showing: 1, tiber coxae; 2, acetabulum; 3, acetabular ramus of ischium; 4, tuber ischii; 5, symphysis pubis; 6, ilium; 7, pibis; and 8, ischium. Only two caudal or coccygeal tail vertebrae are left on a commercial beef carcass.

The shape of the symphysis pubis seen on a side of beef is a useful guide to the sex of the carcass: 1, steer; 2, heifer; and 3, cow, where x shows the position of the pizzle eye. Forelimb skeleton Scapula The most proximal bone of the forelimb is the blade bone or scapula . This is the shape of the blade bone in beef. The scapula is not fused to the vertebral column (like the pelvis in the hindlimb), and this allows muscles that hold the scapula to the ribcage to function as shock absorbers during locomotion. The scapula has a distal socket joint for the next bone in the forelimb, the humerus. This socket joint is called the glenoid cavity . The glenoid cavity is wide and shallow, unlike the ball and socket joint in the hindlimb which is narrow and deep. Along the dorsal edge of the scapula, the bone merges with flexible hyaline cartilage. On the lateral face of the scapula is a prominent ridge of bone called the spine of the scapula.

In beef carcasses, the scapular spine is extended distally as a prominent acromion process. Humerus Proceeding distally down the forelimb, the bone that articulates with the scapula is the humerus . Proximally, the humerus has a relatively flat knob or head to fit into the glenoid cavity of the scapula. Two well defined condyles on the distal end of the humerus contribute to the hinge joint at the elbow. Radius & Ulna Beef shankbones showing: 1, distal end of humerus; 2, olecranon fossa; 3, olecranon process;, 4,radius; 5, ulna; and 6, carpal bones. The radius is joined to the ulna and is the shorter and more anterior bone of the pair. Beef and lamb carcasses have a set of six compact carpal bones remaining on the carcass after slaughter. Before slaughter, the forefeet of cattle and sheep have a large cannon bone located distally to the carpal bones.

A large plan of the pork foot compared to a small plan of beef, showing: AC, accessory carpal; RC, radial carpal; and UC, ulnar carpal. Beef cannon bones are removed with the feet at slaughter since there is virtually no meat on them. Cannon bones sometimes are left on lamb carcasses in the abattoir to prevent the meat contracting proximally up the limb. Each forelimb cannon bone in ruminants is derived by the enlargement and fusion of the third and fourth metacarpal bones. In the human hand, the metacarpal bones lie in the flat part of the hand, between the wrist and the knuckles. If the human hand is placed flat on a desk and is slowly lifted from the wrist, the thumb (digit 1) is the first digit to leave the desk, followed by the index finger and the little finger (digits 2 and 5, respectively). The third and fourth fingers remain on the desk. This demonstrates how the feet of meat animals may have evolved from an original basic plan with five digits. In pigs, digits 3 and 4 on each foot bear most of the body weight and are larger than the lightly loaded digits 2 and 5.

The first digit is absent in pigs. The evolutionary trend towards lifting of the foot and reduction of digits is even more extensive in cattle and sheep. Cattle and sheep have cursorial limbs, long limbs adapted for running. Digits 2 and 5 are reduced to dew claws behind the fetlock. Weight-bearing digits 3 and 4 are enlarged, and their metacarpals are fused to form a long cannon bone. The small bones in the toes of both fore and hind feet are called phalanges. The feet remain on pork carcasses when they are shipped from the abattoir in shipper's style (unsplit carcasses with head plus perirenal or leaf fat) or in packer's style (split sides with leaf fat and head but not jowls removed). However, in a Wiltshire side for bacon production, the feet are removed, together with the head, pelvis, vertebral column and psoas muscles. Hindlimb skeleton Femur The proximal bone of the hindlimb is the femur or round bone. exitThe articular head of the femur is deeply rounded and it bears a round ligament that holds it into the acetabulum.

Another distinctive feature of the femur is the broad groove between the two trochlear ridges located distally. The patella or knee cap slides in this groove. The tension generated by muscles above the knee is transmitted over the knee or stifle joint by the patella to avoid having an important tendon in a vulnerable position over the anterior edge of a joint. In beef and lamb carcasses there is a single major bone, the tibia or shank bone, located distally to the femur. In the corresponding position in a pork carcass there are two parallel bones, a large tibia and a more slender fibula. Tibia and fibula of the pork carcass drawn to the same height and showing: 1, medial condyle, 3, tibia, and 4, fibula. The presence of parallel bones suggests that, at some point in an animal's evolutionary past, rotation of the limb about its axis was possible. For example, rotation of the human wrist involves a partial crossing of the widely spaced ulna and radius but limb rotation is reduced as animals develop cursorial limbs. In cattle and sheep, one of the parallel bones, the fibula, has lost its shaft.

Only a remnant of the head of the fibula may be found. In pigs, the fibula retains its shaft and the bone is mobile at birth. After a few years, however, the fibula becomes fused to the tibia. Distal to the tibia are the tarsal bones of the hock. The structure of the tarsals, metatarsals and phalanges of the hindlimb is similar to that of the carpals, metacarpals and phalanges in the forelimb. Pork carcasses normally are suspended by a gambrel or hooked bar placed under the tendons of the hind feet. Beef carcasses normally are suspended by a hook under the fibular tarsal bone. This bone projects posteriorly and has a rough knob, the tuber calcis, for the insertion of the Achilles tendon at the hock. Poultry skeleton The skeletons of poultry are radically different from those of the farm mammals. Not only is the avian skeleton adapted for flight, but birds and mammals are only distantly related zoologically. The skull has very large eye orbits and a small cranial cavity.

The long double curved neck contains 14 cervical vertebrae, and the ring-like atlas articulates to the skull with only a single occipital condyle. The axis has a large odontoid process that projects anteriorly. There are 7 thoracic vertebrae, but numbers 2 to 5 are fused. Thoracic vertebrae 6 can move freely, but the last thoracic vertebra is fused to the synsacrum. The synsacrum is a fused length of the vertebral column that contains thoracic vertebra 7, 14 lumbo-sacral vertebrae, and the first coccygeal or caudal vertebra, but skeletal fusion in the vertebral column does not occur for many weeks after hatching. There are six caudal vertebrae that, apart from the first, are free and mobile. However, only numbers 2 to 5 are normal vertebrae, since the last one is formed into a three sided pyramidal bone called the pygostyle. There are seven ribs: the first two are free while the last five are attached to the sternum. There are no costal cartilages.

Ribs 2 to 6 each have an uncinate process which overlaps the next posterior rib. The sternum is extremely large. It has a conspicuous ventral ridge in the midline, the CARINA, which increases the area available for attachment of the flight muscles. The dorsal surface of the expanded sternum is concave and forms the floor of a continuous thoracic and abdominal cavity. The bones of the fore limb are greatly modified to form the wing. Plan of wing bones showing: 1,2 and 3, digits; 4, carpometacarpus; 5, radius; 6, ulna; and 7, humerus. (The image at the top corresponds to the distal part of the plan view) Distal to the humerus are the widely spaced radius and ulna. The carpals, metacarpals and digits are reduced to form a stiff skeletal unit for the anchorage of the primary flight feathers. The three digits of the wing are equivalent to digits 2, 3, and 4 in other animals.

The wing articulates with the body at the glenoid cavity which is strengthed by the convergence of three bones, the scapula, the coracoid and the clavicle. Plan view showing: 4, clavicle; and 7, carina of sternum. In birds the coracoid is a separate bone, whereas in mammals it has been reduced to a small integral part of the scapula. The clavicles of right and left sides are fused ventrally to form the furcula or wishbone. Although many mammals have a pair of clavicles, they are absent in cattle, sheep and pigs. The clavicle functions as a strut to support the shoulder joint in animals which have complete mobility of the shoulder joint. Since cattle, sheep and pigs have cursorial limbs with a restricted fore and aft movement, they do not need clavicles. In poultry, the distal end of the coracoid is braced against the sternum. In flight, the body of a bird hangs from its wings at the shoulder joint, hence the more elaborate support for the glenoid cavity. In poultry, the legs show many cursorial adaptations.

Distal to the femur, the fibula is reduced to leave the tibia as the major bone. Plan of poultry leg showing: 1,2,3, and 4, digits, 7, fibula; and 8, femur. In the embryo this occurs as a result of the differential growth and translocation of the distal part of the fibula to become part of the tibia. The proximal tarsal bones are fused to the distal end of the tibia to increase its length, and the whole skeletal unit may be called the tibiotarsus. The distal tarsal bones are incorporated into the proximal end of a single bone, the tarsometatarsus, which also includes the fused metatarsals 2, 3 and 4. Of the four digits which form the bird's claw, digit 1 is directed posteriorly while digits 2, 3 and 4 are anterior. This adpatation enables the bird to perch. The ilium is fused to the synsacrum. Instead of being fused in the midline, the pubic bones are separate, and they project backwards as thin rods.

Plan of poultr pelvis (anterior to the left) showing: 1, obturator foramen; Horse Anatomy - Skeleton & Anatomy Diagram Of A Horse You are here: Home / Horse Anatomy Horse Anatomy ADVERTISEMENT Horses have, on average, a skeleton of 205 bones. A significant difference in the bones contained in the horse skeleton, as compared to that of a human, is the lack of a collarbone. Their front limb system is attached to the spinal column by a powerful set of muscles, tendons and ligaments that attach the shoulder blade to the torso. The horses legs and hooves are also unique, interesting structures. Their leg bones are proportioned differently from those of a human. For example, the body part that is called a horses ‘knee’ is actually the carpal bones that correspond to the human wrist. Similarly, the hock contains the bones equivalent to those in the human ankle and heel. The lower leg bones of a horse correspond to the bones of the human hand or foot.

The fetlock (incorrectly called the ‘ankle’) is actually the proximal sesamoid bones (bones that are typically found in locations where a tendon passes over a joint) between the cannon bones (a single equivalent to the human metacarpal (the intermediate part of the hand skeleton) or metatarsal bones (five long bones of the foot)) and the proximal phalanges (bones found in the limbs of most vertebrates), located where one finds the ‘knuckles’ of a human. A horse also has no muscles in its legs below the knees and hocks, only skin and hair, bone, tendons, ligaments, cartilage and the assorted specialized tissues that make up the hoof. The skeleton gives support for the muscles, protection for the internal organs, and possesses the necessary mobility of its parts for the horse to move at various speeds or lie down or graze. Below is a diagram of the some of the most important bones within a horse: Below is a diagram of a horses body parts – the numbers on the diagram correspond with the body part names: 1. muzzle 2. cheek 3. face 4. forehead 5. poll 6. neck 7.

crest 8.jaw 9. withers 10. heart girth 11. back 12. loin 13. coupling 14. croup 15. thigh 16. point of buttock 17. quarters 18. gaskin 19. hock 20. cannon 21. fetlock joint 22. pastern 23. stifle 24. rear flank 25. under line 26. ribs 27. fore flank 28. elbow 29. forearm 30. knee 31. cannon 32. fetlock joint 33. pastern 34. foot 35. arm 36. breast 37. point of shoulder 38. shoulder 39. throat latch Search the Animals Body Parts of the Horse Please be sure to visit our sponsor, Horse and Country Singles Let them know you appreciate their support of these articles! Be sure to visit our sponsor, TrailMaster Saddles , Let them know you appreciate their support of these articles!

To Evaluate a horses conformation you must know several common names associated with horse anatomy. Points of a Horse This chart can be used to review or learn some body parts of the horse. First look at the number and see where the line is indicating on the horses body. Now name that part yourself. THEN place the mouse over the number to see the name of the part, for further information, click on that number to read a description of the body part. NOTE: Mouse over Function will not work in older browsers. Works Best with NETSCAPE For a free download, BOOKMARK page to get back! 1) Poll; The poll is the bony prominence lying between the ears. Except for the ears, it is the highest point on the horses body when it is standing with its head up. 2) Crest; Moderately lean in mares but inclined to be more full in stallions. Curved topline of the neck. 3) Forehead; The forehead should be broad, full and flat. 4) Nostrils ; The nostrils should be capable of wide dilation to permit the maximum inhalation of air, yet be rather fine.

5) Muzzle; The head should taper to a small muzzle, the lips should be firm and the lower lip should not have the tendency to sag. 6) Point of Shoulder ; The point of shoulder is a hard, bony prominence surrounded by heavy muscle masses. 7) Breast; The Breast is a muscle mass between the forelegs, covering the front of the chest. Back to Top 8) Chest; An ideal chest is deep and contains the space necessary for vital organs. A narrow chest can lead to interference with the front legs. Chest muscles should be well developed and form an inverted "V". The prominence of chest muscling depends on the breed. 9) Forearm; The forearm should be well muscled, it extends from the elbow to the knee. 10) Knee; The knee is the joint between the forearm and the cannon bone. 11) Coronet; The coronet is the band around the top of the hoof from which the hoof wall grows. 12) Hoof; The hoof refers to the horny wall and the sole of the foot. The foot includes the horny structure and the pedal bones and navacular bones, as well as other connective tissue.

13) Pastern; The pastern extends from the fetlock to the top of the hoof. 14) Sesamoid; 15) Flexor Tendons; The flexor tendons run from the knee to the fetlock and can be seen prominently lying behind the cannon bone, when it runs parallel to the cannon bone it constitutes the desired "flat bone". Back to Top 16) Fetlock; The fetlock is the joint between the cannon bone and the pastern. The fetlock joint should be large and clean. 17) Cannon; The cannon bone lies between the knee and fetlock joint, and is visible from the front of the leg. It should be straight. 18) Underline; 19) Hock; The hock is the joint between the gaskin and the cannon bone, in the rear leg. The bony protuberance at the back of the hock is called the point of hock. 20) Gaskin; The gaskin is the region between the stifle and the hock. 21) Stifle; The stifle is the joint at the end of the thigh corresponding to the human knee.

22) Flank; The flank is the area below the loin, between the last rib and the massive muscles of the thigh. 23) Loin; The loin or coupling is the short area joining the back to the powerful muscular croup ( rump). 24) Croup; The croup (rump) lies between the loin and the tail. When one is looking from the side or back, it is the highest point of the hindquarters. 25) Back; The back extends from the base of the withers to where the last rib is attached. Back to Top 26) Withers; The withers is the prominent ridge where the neck and the back join. At the withers, powerful muscles of the neck and shoulders attach to the elongated spines of the second to sixth thoracic vertebrae. The height of a horse is measured vertically from the withers to the ground, because the withers is the horse's highest constant point. 27) Throat Latch; The neck should be fine at the throat latch to allow the horse ease of flexation. 28) Neck; Lightweight horses should have reasonably long necks for good appearance and proper balance.

It should blend smoothly into the withers and the shoulders and not appear to emerge between the front legs. 29) Shoulder; Shoulders should be overlain with lean, flat muscle and blend well into the withers. 30) Barrel; The barrel should be narrower at the shoulders and widen at the point of coupling (loins). 31) Girth; This is the point that a horses should be measured to determine the heart girth which can be used to determine the horses weight. 32) Elbow; The elbow is a bony prominence lying against the chest at the beginning of the forearm. 33) Hindquarters; The hindquarters give power to the horse. They should be well muscled when viewed from the side and rear. Conformation, Keeping it all in Balance. Althought a horses basic body conformation will vary by breed, all horses should have basic "athletic" structural attributes. A horses conformation determines how well it can perform the functions asked of it. When the Bone Breaks | TheHorse.com When the Bone Breaks Newsletters They shoot horses, don't they? We all know about the rather depressing traditional "cure" for a horse with a broken leg.

But there's good news--they "shoot" them a lot less often these days. The reason is that remarkable advances in equine fracture repair now mean that many horses which in years past could not have been saved, are not only recovering from their injuries, but are going on to successful performance careers, even on the racetrack. Alicia Bertone, DVM, PhD, Diplomate ACVS, an equine orthopedic surgeon at The Ohio State University, attributes the change in prognosis for fracture patients to a combination of factors. "Certainly," she says, "the equipment we're using has improved, and we have more accredited surgeons now who are better trained in the techniques needed for fracture repair. But we also have better anesthesia techniques and recovery facilities. It's the assembly of the team for managing these injuries that has improved so much. "As owners become more aware that many fractures are now repairable, they're requiring their veterinarians to become more educated as to how to manage a fracture injury and get the horse to a surgical center in better condition.

The cleaner and more immobile the fracture site when the horse arrives, the easier it is to repair the damage." Most racetracks now have equine ambulances and trained emergency technicians equipped with sedatives and commercially available splints like the Kimzey leg saver (designed specifically for catastrophic injuries of the fetlock) and the Farley boot (which resembles a ski boot). Equipment like this can be a tremendous boon in immobilizing a fractured limb before the horse does further damage to the ends of the bone, the skin, and the surrounding blood vessels, and can vastly improve his chances for recovery. "A fracture is a catastrophic injury," Bertone affirms, "and nine out of 10 cases should have some surgical intervention to assure correct healing. But bone is one of the fastest-healing tissues in the body--it heals faster than tendons or ligaments, and study after study has demonstrated that it heals to 100% of its previous strength.

With correct care, most fractures heal within four months, and horses are often back up to their previous athletic potential within a year." Bertone, who has been doing orthopedic surgeries for more than 15 years, notes that Ohio State has one of the longest histories in the country for dealing with equine fractures. Albert Gabel, DVM, now retired from OSU, was a pioneer in fracture repair, and Larry Bramlage, DVM, Diplomate ACVS, now considered one of the pre-eminent equine orthopedists in the United States, trained under Gabel and was based for many years at the university, where he was instrumental in making fracture repair a viable alternative. "I consider myself part of the next generation of orthopedists here," she says. "For us, fracture repair is now mainstream; OSU even hosts the annual international fracture fixation course for both large and small animals." Fracture Hows And Whys A fracture might be the result of a single, violent event--such as being kicked by another horse--or it might be the end result of repeated wear and tear that outstrip the body's attempts at repair.

"Microfractures" in the bone structure are a common response to exercise stress, and if the horse is allowed sufficient recovery time between high-stress efforts, his system will repair these tiny fissures in the bone, reinforcing and remodeling the matrix so it can better cope with repeated stresses. (This process can go on for years--studies examining cross-sections of cannon bones taken from British steeplechase horses have indicated that bone thickening and remodeling can continue until the horse is 10 or more years of age.) If the bone is subjected to enough force before the body has had time to mend these microfractures, they can multiply, until finally the bone cracks or shatters. (In addition to stress fractures and those that are the result of sudden trauma, horses can suffer "chip" fractures of the knee, fetlock, or hock joint. Chips sometimes are the result of subchondral bone cysts stemming from developmental orthopedic disease, and often are easily dealt with by arthroscopic surgery.) Diagnosis of fractures is remarkably similar in the vast majority of cases. Most people report hearing a loud popping or cracking noise when the injury occurs.

Soon after, swelling and significant pain occur at the site, along with the inability of the horse to bear weight on the limb. These factors, in addition to radiographic confirmation, all point to a fracture. Among major fractures, Bertone names several types as being common in racehorses (generally considered the most highly stressed equine athletes). Racing Injuries "Breakdown fractures are the classic racehorse fractures," says Bertone. "A breakdown occurs when the support structures of the fetlock give way, tearing the suspensories and fracturing the sesamoid bones on the back of the ankle as they hit the ground surface." Typically occurring in Thoroughbreds, breakdown fractures are repairable if the joint is immobilized before the horse does more damage to it. Often, the problem is that the horse continues to gallop on it for a few strides before his rider can pull him up, each stride grinding together bone fragments and damaging the blood supply and the surrounding skin, essentially making hamburger of the area and causing too much injury for the surgeon to repair. Temporary splints like the Kimzey leg saver, however, have improved the chances of saving horses with this type of injury.

Bertone says that through the use of a technique called fetlock arthrodesis, plates and screws can be attached to the bone to help stabilize the joint and eventually fuse it. The result is usually a horse which is sound only for breeding, not performance, but which will be comfortable on the limb. Condylar Fracture Another typical injury for Thoroughbred racehorses is the condylar fracture of the cannon bone. Typically seen in the left front leg, a condylar fracture shows up on radiographs as a crack that goes laterally up the cannon from the fetlock joint and out the side of the bone, essentially "knocking a corner" off the cannon bone--a piece sometimes up to six inches long. Condylar fractures also are seen in Standardbreds, typically as a left front lateral injury, or on the right hind cannon in a medial position. "The hind cannon fractures tend to spiral and go higher up the cannon bone," Bertone notes, "which is unique to harness racing athletes." Most condylar fractures are the direct result of repeated racing stress.

"Condylar fractures can be incomplete and non-displaced, meaning that the bone fragment hasn't broken away from the cannon and is still in its original position," says Bertone, "or they can be complete and displaced, which is the worst-case scenario. If the fracture is complete and displaced, it's often visible under the skin as a painful bump--and when we incise the area for repair, there will be bleeding and hemorrhage." Repair for a condylar fracture involves using multiple stainless steel screws inserted in a lag fashion, which compresses the bone fragment up against the parent bone as snugly as possible. "The goal is to stabilize the fetlock joint for fast healing," says Bertone, "and to align the fetlock correctly so that there are no protruding bits of bone which could later contribute to arthritis." Even if the fracture is incomplete, Bertone recommends the use of screws as the best method of repair. Depending on the degree of displacement and the amount of damage to the surrounding blood vessels (which are crucial points to healing), condylar fractures usually resolve fairly well, and the prognosis is often good for a return to performance the following year.

Sagittal Fracture Sagittal fractures of the P1 (long pastern bone) are another serious fracture common to Thoroughbreds and Standardbreds. "This is a fracture straight down the front of the P1 bone," Bertone says. "Just like the condylar fracture, this injury can be either incomplete and non-displaced, or complete and displaced." A sagittal fracture can also be "comminuted" or in many pieces. A comminuted fracture usually is the result of the bone's shattering during a burst of peak speed. Repairing a sagittal fracture also is done by inserting screws lag fashion, squeezing the bone fragment up tightly against the parent bone to leave little or no gap, and aligning the joint as smoothly as possible. "If a fragment is displaced," explains Bertone, "we have to do what's called 'reducing' the fracture, which means we try to replace the fragment exactly where it belongs so that the joint can work correctly when it's healed." With a badly comminuted fracture, she continues, "you can't always put all the fragments back where they belong, but you do the best you can." Some fragments might have to be removed.

Then the injury is usually fitted with a cast to stabilize it. Bertone estimates that 85% of horses with sagittal P1 fractures can return to their racing careers--an encouraging prognosis. Cortical Fractures Dorsal cortical fractures are stress fractures of the front of the cannon bone--bucked shins taken to their injurious extreme. On X rays, a crack on the cannon bone usually will be clearly visible, most often in the middle or the upper third of the bone. "That area of the bone takes a lot of stress," Bertone says, "and the bone tries to respond by becoming stronger and thicker." But if the stresses are greater than the time available for healing, something has to give. Dorsal cortical fractures are one of the few types of equine fractures in which the horse might be willing to bear some weight on the injured leg, but the bump on the front of the bone usually is easy to feel with the fingers. One or more screws generally are used to repair this type of fracture, and the prognosis generally is very good for a full return to athletic performance.

Splint Fractures Splint bone fractures are another common injury associated with the cannons; they can occur on either the distal (lower) or proximal (upper) portions of the splint bone, with the former being far more common. Although many distal fractures will resolve on their own with four to six months of stall rest, the large bump that results prompts many owners to opt for removal of the fractured portion of the bone instead. This is an uncomplicated surgery with a good prognosis for a full return to work. Cannon Fractures Much more catastrophic are cannon bone fractures that shatter the bone across the middle. "In these cases, you see a loose, dangling leg," says Bertone. But she assures us that some of these injuries, despite their shocking looks, are repairable. "It depends on how much damage has been done to the arteries and the skin of the leg. If the horse keeps galloping on it, the blood supply will be damaged and the leg will be left open to infection, making for a poor prognosis. But some of these injuries are repairable with plates and screws, and sometimes the horse even returns to full soundness if the injury doesn't involve any joints.

The best results occur when this sort of injury happens to a foal, because the limb has to bear less weight while it heals." Performance Horse Injuries In addition to all of these fracture types which occur in racehorses, there are several others that are more likely to show up in performance horses. One is a fracture of the P2 (short pastern bone), which tends to occur in working Quarter Horses which are asked to perform sliding stops. The hind pasterns are most often involved. In the case of a P2 fracture, arthrodesis is the treatment of choice. "We do that because if you just fix the fracture, you always get significant arthritis in the pastern joint later," says Bertone. "Instead, we use plates and screws to help fuse the joint. The pastern is a low-motion joint, so you can fuse it and not change the gait of the horse; in fact, this surgery is about 80% successful. "What limits it is whether the coffin joint is involved.

It's difficult to work with coffin joint fractures because access is limited--you have to work from above, and it's difficult to get the alignment of the joint just right or get a screw exactly where you want it to be." Coffin Fractures Fractures of the coffin bone (P3) itself are tackled slightly differently. Bertone says she has seen this injury in virtually every type of horse, from jumpers to draft horses, and that the cause is often unclear. She conjectures, however, that extremely sharp turns, or chance circumstances like landing on a rock, could be to blame for at least some coffin bone fractures. There actually are two types of coffin bone fractures: the sagittal type, which Bertone describes as "straight down the middle" (most often seen in jumpers and event horses), and "wing" fractures, in which a section from the inside or outside "wing" of the bone cracks or snaps off. "This is more commonly seen as a racing injury," she says, "as a result of galloping on turns.

They're trickier because they often involve the joint." Most coffin bone fractures are treated not with plates or screws, but by immobilizing the foot initially with a cast, then replacing the cast in one to two weeks with a heavy support shoe and thick leather sole pads. Multiple clips, or a metal rim that goes all the way around the wall of the hoof, help the shoe restrict the natural expansion and elasticity of the hoof, essentially acting as a cast. A horse shod in this fashion and rested for about five months, then shod with a lighter shoe that often includes bar support for the sole, has a good prognosis, but coffin bone injuries are slow to heal, and sometimes never resolve entirely. "Some of these horses have to wear bar shoes all their lives," says Bertone. "I've had better outcomes for (coffin bone fractures) in young animals--from weanlings up to about 2-year-olds. When I see it in a 15-year-old jumper, I have to say the prognosis isn't quite as good." Some sagittal coffin bone fractures can be repaired with screws.

A hole is drilled laterally in the hoof wall to gain access to the bone, and the screw is placed behind the hoof wall--almost as you would countersink a screw in wood. "The coffin bone is about an inch into the middle of the hoof," Bertone explains, "so you don't see anything once the screw is in place. Pink granulation tissue will quickly fill the hole in the hoof wall, and, as the hoof grows down, you lose the hole and the screw is buried in the center of the hoof. It's tricky, though, because there is a risk of fluid buildup." Immediate attention to immobilizing the hoof is critical with a coffin bone fracture. Unfortunately, because there is no swelling or obvious fracture site, this injury often is mistaken for any of a number of other types of lamenesses. A bounding digital pulse, an inability to bear weight on the foot, and a sore reaction to hoof-testers usually tell the tale.

Olecranon Fracture A break common to foals and weanlings is a fracture of the olecranon (the point of the elbow), often the result of a kick during rambunctious play, or of falling over backwards, something to which foals are more prone than adult horses. "Many people don't even see it happen," says Bertone. "They just discover the result--a foal who has a classic 'dropped elbow' stance, and won't bear weight on the limb. It's repairable with plates and screws, and the prognosis is good in young horses," with many going on to exhibit no signs of the injury as adults. Using screws and plates on the bones of a young growing horse can be a tricky procedure because placement across the growth plates can contribute to abnormalities as the horse matures. "We try not to place the plates so that they interfere with the growth plates if at all possible," says Bertone, who notes that if this is accomplished correctly, the plates need not be removed as the horse grows.

Other Common Fractures Two more common injuries of pleasure and performance horses include fractures of the long bones of the upper limbs (the humerus in the forelegs, and the femur behind), and fractures of the tuber coxae, often called a "knockdown hip" or "dropped hip." Fractures of the long bones, usually caused by some catastrophic event such as being hit by a car, a trailer accident, or a violent kick by a pasture-mate, generally demonstrate what Bertone describes as "massive swelling," and unfortunately have a poor prognosis in adult horses, since these bones are crucial to weight-bearing. (Bertone noted that horses suffering from this sort of injury often suffer laminitis in the opposite, supporting limb.) In foals, the outlook is a bit more promising, although the risk of problems with the "good" leg remains along with the risk of long-term growth deformities. A knockdown hip, on the other hand, often heals on its own. Usually the result of the horse's banging a hip on a doorframe and fracturing the ilium of the pelvis, a knockdown hip is easy to spot, since the bone fragment tends to sink in and down in the flesh.

The injury is non-weight-bearing at first, but since it doesn't affect the hip joint itself, the prognosis is generally good for a return to light athletic work. (Because the major gluteal muscles do originate at the ilium, however, Bertone suspects that a horse affected by this injury would be unlikely to have enough power in his hindquarters for a successful return to racing.) The hip might take as much as six months to heal, however, and the area will never look normal--the depression is permanent. Naturally, there are a number of other potential sites for fractures, with varying prognoses for recovery. But the techniques for repairing these injuries are, for the most part, very similar--although there is something of an art to placing screws in living bone at exactly the right angles to best encourage correct healing of a fracture. Methods Of Repair Bertone says that the fracture repair team at OSU works almost exclusively with specially designed stainless steel screws. "They're well-designed for the purpose," she says, "and we have had good success with them." In some cases, the screws are placed permanently, while in other instances, the screws are removed once the fracture is resolved.

"In condylar fractures," she says, "the screws are sometimes removed--depending on the severity of the original injury and how well it has healed. I rarely remove them for sagittal P1 fractures. And in dorsal cortical fractures--which are sometimes treated with a combination of screws and a technique called osteostyxsis, in which small holes are drilled into the bone's marrow cavity to encourage the development of new blood vessels and healing cells--I usually remove the screws eventually." When plates are involved in a fracture repair, their removal depends on the horse's eventual use. "I might remove a plate for a top athlete, because extreme exercise might cause pain at the site. But for a pleasure horse who's only being used lightly, I'd probably leave it in there," says Bertone. Removal of screws or plates might require a second full surgery, but the OSU team has found that many screws can be removed with the horse standing, with the help of sedatives--a far less stressful procedure. Screws are most often removed if an infection has developed, or when they have worked themselves loose and cause irritation and pain.

As long as they remain tightly in place, they should cause no problems within the bone, despite the fact that they are considerably stronger and more rigid than the bone tissue surrounding them. Two new products offering promise for certain types of fracture repair are the lactic acid bioabsorbable screws detailed in last month's issue, and titanium screws, which have the potential to be less corrosive, and more flexible, than their stainless steel counterparts--in short, more compatible with the natural properties of bone. "I haven't used them (titanium screws) myself," says Bertone, "but they are supposed to interface better with the bone. They are still rather experimental, though, and they're pricey ($300 or more per screw, as compared to about $25 per screw for stainless steel)." A horse which has undergone surgery for fracture repair might or might not receive a cast to help immobilize the injury. "We sometimes put a cast on just for recovery (from the anesthesia), sometimes for a bit longer, and some surgeries are fine with just a light support bandage over the sutures," Bertone explains.

"We cast only if necessary to establish weight-bearing on the limb, which needs to happen as soon as possible so that the horse doesn't develop laminitis in the opposite leg." The casting material of choice for horses is a light fiberglass resin, which is waterproof and fast-drying. A new development is a casting foam that molds to the horse's leg and stays soft and malleable. Used under the fiberglass cast, it improves the comfort of the apparatus and helps immobilize the injury site at the same time. Fracture repair is a field that has grown by leaps and bounds in the last 20 years, and new research is improving the prognosis for horses every day. The best part is that these injuries, which once were death sentences for a horse, now are routinely repaired, saving careers and lives. About the Author

Question: In which part of an animal is the cannon bone?
Answer: Leg