The pronghorn is a species of artiodactyl mammal indigenous to interior western and central North America. Though not an antelope, it is known colloquially in North America as the American antelope, prong buck, pronghorn antelope, prairie antelope, or antelope because it resembles the true antelopes of the Old World and fills a similar ecological niche due to parallel evolution, it is the only surviving member of the family Antilocapridae. During the Pleistocene epoch, about 12 antilocaprid species existed in North America. Three other genera existed when humans are now extinct; as a member of the superfamily Giraffoidea, the pronghorn's closest living relatives are the giraffes and okapi. The Giraffoidea are in turn members of the infraorder Pecora, making pronghorns more distant relatives of the Cervidae and Bovidae, among others; the scientific name of the pronghorn is Antilocapra americana. The pronghorn is the sole extant member of the family Antilocapridae; this species was first described by American ornithologist George Ord in 1815.
The pronghorn were first seen and described by Spanish explorers in the 16th century, but were not formally recorded or scrutinised till the 1804–1806 expedition by Captain Meriwether Lewis and Second Lieutenant William Clark. The expedition, which aimed to unravel water routes in the continent for commercial purposes, led to the discovery or formal recognition of a variety of flora and fauna of North America. Following the discovery of a few subspecies of the sharp-tailed grouse and Clark came across the pronghorn near the mouth of the Niobrara River, in present-day Nebraska. Clark was the first to kill a pronghorn, described his experience as follows: I walked on shore to find an old Vulcanoe... in my walk I killed a Buck Goat of this Countrey, about the height of the Grown Deer, its body Shorter the horns, not hard and forks 2⁄3 up one prong Short the other round & Sharp arched, is above its Eyes the Color is a light gray with black behind its ears down the neck, its face white round its neck, its Sides and its rump round its tail, Short & white.
Lewis and Clark made several other observations on the behavior of the pronghorn and how the local tribes hunted them. They described the animal, which they referred to as the "Antelope" or the "Goat", as follows: Of all the animals we have seen the Antelope seems to possess the most wonderful fleetness. Shy and timorous they repose only on the ridges, which command a view of all the approaches of an enemy... When they first see the hunters they run with great velocity... The Indians near the Rocky Mountains hunt these animals on horseback, shoot them with arrows; the Mandans' mode of hunting them is to form a large, strong pen or fold, from which a fence made of bushes widens on each side. The animals are surrounded by the hunters, driven towards this pen, in which they imperceptibly find themselves enclosed, are at the mercy of the hunters. Pronghorns have distinct white fur on their rumps, breasts and across their throats. Adult males are 1.3–1.5 m long from nose to tail, stand 81–104 cm high at the shoulder, weigh 40–65 kg.
The females weigh 34 -- 48 kg. The feet have two hooves, with no dewclaws, their body temperature is 38 °C. The orbits are prominent and set high with never an anteorbital pit, their teeth are hypsodont, their dental formula is 0.0.3.33.1.3.3. Each "horn" of the pronghorn is composed of a slender, laterally flattened blade of bone that grows from the frontal bones of the skull, forming a permanent core; as in the Giraffidae, skin covers the bony cores, but in the pronghorn, it develops into a keratinous sheath, shed and regrown annually. Unlike the horns of the family Bovidae, the horn sheaths of the pronghorn are branched, each sheath having a forward-pointing tine. Males have a horn sheath about 12.5–43 cm long with a prong. Females have smaller horns that range from 2.5–15.2 cm and sometimes visible. Males are further differentiated from females in having a small patch of black hair at the angle of the mandible. Pronghorns have a musky odor. Males mark territory with a preorbital scent gland, on the sides of the head.
They have large eyes with a 320° field of vision. Unlike deer, pronghorns possess a gallbladder; the pronghorn is the fastest land mammal in the Western Hemisphere, being built for maximum predator evasion through running. The top speed is hard to measure and varies between individuals, it is cited as the second-fastest land animal, second only to the cheetah. It can, sustain high speeds longer than cheetahs. University of Idaho zoologist John Byers has suggested the pronghorn evolved its running ability to escape from extinct predators such as the American cheetah, since its speed exceeds that of extant North American predators. Compared to its body size, the pronghorn has a large windpipe and lungs to allow it to take in large amounts of ai
The Malayan tapir called the Asian tapir or Indian tapir, is the largest of the five species of tapir and the only one native to Asia. The scientific name refers to the species' natural habitat. In the Malay language, the tapir is referred to as cipan, tenuk or badak tampung; the animal is identified by its markings, most notably the light-colored patch that extends from its shoulders to its rear end. The rest of its hair is black, except for the tips of its ears, which, as with other tapirs, are rimmed with white; this pattern is for camouflage. Malayan tapirs grow to between 1.8 and 2.5 m in length, not counting a stubby tail of only 5 to 10 cm in length, stand 90 to 110 cm tall. They weigh between 250 and 320 kg, although some adults can weigh up to 540 kg; the females are larger than the males. Like the other types of tapir, they have long, flexible proboscises, they have four three toes on each back foot. The Malayan tapir has rather excellent hearing and sense of smell, they have a large sagittal crest, a bone running along the middle of the skull, necessary for muscle attachment.
They have unusually positioned orbits, an unusually shaped cranium with the frontal bones elevated, a retracted nasal incision. All of these modifications to the normal mammal skull are, of course, to make room for the proboscis; this proboscis caused a retraction of bones and cartilage in the face during the evolution of the tapir, caused the loss of some cartilages, facial muscles, the bony wall of the nasal chamber. Malayan tapirs have poor eyesight, making them rely on their excellent sense of smell and hearing to go about in their everyday lives, they have beady eyes with brown irises on either side of their faces. Their eyes are covered in a blue haze, corneal cloudiness thought to be caused by repetitive exposure to light. Corneal cloudiness is a condition; the cornea is necessary for the transmitting and focusing of outside light as it enters the eye, cloudiness can cause vision loss. This causes the Malayan tapir to have inadequate vision, both on land and in water, where they spend the majority of their time.
As these tapirs are most active at night and since they have poor eyesight, it is harder for them to search for food and avoid predators in the dark. A small number of melanistic Malayan tapirs have been observed. In 1924, an all-black tapir was sent to Rotterdam Zoo and was classified as a subspecies called Tapirus indicus brevetianus after its discoverer, Captain K. Brevet. In 2000, two melanistic tapirs were observed during a study of tigers in the Jerangau Forest Reserve in Malaysia; the cause of this variation may be a genetic abnormality similar to that of black panthers that appear in populations of spotted leopards or spotted jaguars. However and until, more T. i. brevetianus individuals can be studied, the precise explanation for the trait will remain unknown. The gestation period of the Malayan tapir is about 390–395 days, after which a single offspring, weighing around 15 pounds, is born. Malayan tapirs are the largest of the five tapir species at birth and grow more than their congeners.
Young tapirs of all species have brown hair with white stripes and spots, a pattern that enables them to hide in the dappled light of the forest. This baby coat fades into adult coloration between seven months after birth. Weaning occurs between six and eight months of age, at which time the babies are nearly full-grown, the animals reach sexual maturity around age three. Breeding occurs in April, May or June, females produce one calf every two years. Malayan tapirs can live up to 30 years, both in captivity. Malayan tapirs are solitary creatures, marking out large tracts of land as their territory, though these areas overlap with those of other individuals. Tapirs mark out their territories by spraying urine on plants, they follow distinct paths, which they have bulldozed through the undergrowth. Herbivorous, the animal forages for the tender shoots and leaves of more than 115 species of plants, moving through the forest and pausing to eat and note the scents left behind by other tapirs in the area.
However, when threatened or frightened, the tapir can run despite its considerable bulk, can defend itself with its strong jaws and sharp teeth. Malayan tapirs communicate with high-pitched whistles, they prefer to live near water and bathe and swim, they are able to climb steep slopes. Tapirs are active at night, though they are not nocturnal, they tend to eat soon after sunset or before sunrise, they will nap in the middle of the night. This behavior characterizes them as crepuscular animals; the Malayan tapir was once found throughout the tropical lowland rainforests of Southeast Asia, including Cambodia, Laos, Myanmar and Vietnam. However, its numbers have decreased in recent years, today, like all tapirs, it is in danger of extinction; because of their size, tapirs have few natural predators, reports of killings by tigers are scarce. The main threat to the Malayan tapirs is human activity, including deforestation for agricultu
Bison are large, even-toed ungulates in the genus Bison within the subfamily Bovinae. Two extant and six extinct species are recognised. Of the six extinct species, five became extinct in the Quaternary extinction event. Bison palaeosinensis evolved in the Early Pleistocene in South Asia, was the evolutionary ancestor of B. priscus, the ancestor of all other Bison species. From 2 MYA to 6,000 BC, steppe bison ranged across the mammoth steppe, inhabiting Europe and northern Asia with B. schoetensacki, North America with B. antiquus, B. latifrons, B. occidentalis. The last species to go extinct, B. occidentalis, was succeeded at 3,000 BC by B. bison. Of the two surviving species, the American bison, B. bison, found only in North America, is the more numerous. Although known as a buffalo in the United States and Canada, it is only distantly related to the true buffalo; the North American species is composed of two subspecies, the Plains bison, B. b. bison, the Wood bison, B. b. athabascae, the namesake of Wood Buffalo National Park in Canada.
A third subspecies, the Eastern Bison is no longer considered a valid taxon, being a junior synonym of B. b. bison. References to "Woods Bison" or "Wood Bison" from the eastern United States confusingly refer to this subspecies, not B. b. athabascae, not found in the region. The European bison, B. bonasus, or wisent, is found in Europe and the Caucasus, reintroduced after being extinct in the wild. While all bison species are classified in their own genus, they are sometimes bred with domestic cattle and produce fertile offspring called beefalo or zubron; the American bison and the European bison are the largest surviving terrestrial animals in North America and Europe. They are typical artiodactyl ungulates, are similar in appearance to other bovines such as cattle and true buffalo, they are muscular with shaggy coats of long hair. Adults grow up to 1.8 metres in length for American Bison and up to 2.8 metres in length for European bison. American bison can weigh from 400 kilograms to 900 kg and European bison can weight from 800 kilograms to 1,000 kilograms.
European bison tend to be heavier than American bison. Bison are nomadic grazers and travel in herds; the bulls leave the herds of females at two or three years of age, join a male herd, which are smaller than female herds. Mature bulls travel alone. Towards the end of the summer, for the reproductive season, the sexes commingle. American bison are known for living in the Great Plains, but had a much larger range including much of the eastern United States and parts of Mexico. Both species were hunted close to extinction during the 19th and 20th centuries, but have since rebounded; the American Plains bison is no longer listed as endangered, but this does not mean the species is secure. Genetically pure B. b. bison number only ~20,000, separated into fragmented herds—all of which require active conservation measures. The Wood bison is on the endangered species list in Canada and is listed as threatened in the United States, though there have been numerous attempts by beefalo ranchers to have it removed from the Endangered Species List.
Although superficially similar and behavioural differences exist between the American and European bison. The American species has 15 ribs, while the European bison has 14; the American bison has four lumbar vertebrae. Adult American bison are less slim in have shorter legs. American bison tend to graze more, browse less than their European relatives, their anatomies reflect this behavioural difference. The body of the American bison is hairier, though its tail has less hair than that of the European bison; the horns of the European bison point through the plane of their faces, making them more adept at fighting through the interlocking of horns in the same manner as domestic cattle, unlike the American bison, which favours butting. American bison are more tamed than their European cousins, breed with domestic cattle more readily; the bovine tribe split about 5 to 10 million years ago into the buffalos and a group leading to bison and taurine cattle. Thereafter, the family lineage of bison and taurine cattle does not appear to be a straightforward "tree" structure as is depicted in much evolution, because evidence of interbreeding and crossbreeding is seen between different species and members within this family many millions of years after their ancestors separated into different species.
This crossbreeding was not sufficient to conflate the different species back together, but it has resulted in unexpected relationships between many members of this group, such as yak being related to American bison, when such relationships would otherwise not be apparent. A 2003 study of mitochondrial DNA indicated four distinct maternal lineages in tribe Bovini: Taurine cattle and zebu Wisent American bison and yak and Banteng and gayalHowever, Y chromosome analysis associated wisent and American bison. An ear
Laminitis is a disease that affects the feet of ungulates and is found in horses and cattle. Clinical signs include foot tenderness progressing to inability to walk, increased digital pulses, increased temperature in the hooves. Severe cases with outwardly visible clinical signs are known by the colloquial term founder, progression of the disease will lead to perforation of the coffin bone through the sole of the hoof or being unable to stand up requiring euthanasia; the bones of the hoof are suspended within the axial hooves of ungulates by layers of modified skin cells, known as laminae or lamellae, which act as shock absorbers during locomotion. In horses, there are about 550–600 pairs of primary epidermal laminae, each with 150–200 secondary laminae projection from their surface; these interdigitate with equivalent structures on the surface of the coffin bone, known as dermal laminae. The secondary laminae contain basal cells; the basement membrane is attached to the coffin bone via the connective tissue of the dermis.
Laminitis means inflammation of the laminae, while it remains controversial whether this is the primary mechanism of disease, evidence of inflammation occurs early in some instances of the disease. A severe inflammatory event is thought to damage the basal epithelial cells, resulting in dysfunction of the hemidesmosomes and subsequent reduction in adherence between the epithelial cells and the basement membrane. Normal forces placed on the hoof are strong enough to tear the remaining laminae, resulting in a failure of the interdigitation of the epidermal and dermal laminae between the hoof wall and the coffin bone; when severe enough, this results in displacement of the coffin bone within the hoof capsule. Most cases of laminitis occur in both front feet, but laminitis may be seen in all four feet, both hind feet, or in cases of support limb laminitis, in a single foot; the mechanism is the subject of much research. Three conditions are thought to cause secondary laminitis: Sepsis/endotoxemia or generalized inflammation Endocrinopathy Trauma: concussion or excessive weight-bearingInflammationInflammatory events that are associated with laminitis include sepsis, retained placenta, carbohydrate overload, enterocolitis and contact with black walnut shavings.
In these cases, there is an increase in blood flow to the hoof, bringing in damaging substances and inflammatory cells into the hoof. EndocrinopathyEndocrinopathy is the result of improper insulin regulation, is most seen with pituitary pars intermedia dysfunction and equine metabolic syndrome, as well as obesity and glucocorticoid administration. In cases of EMS, most episodes occur in the spring. TraumaMechanical laminitis starts when the hoof wall is pulled away from the bone or lost, as a result of external influences. Mechanical laminitis can occur when a horse habitually paws, is ridden or driven on hard surfaces, or in cases of excessive weight-bearing due to compensation for the opposing limb, a process called support limb laminitis. Support limb laminitis is most common in horses suffering from severe injury to one limb, such as fracture, resulting in a non-weight bearing state that forces them to take excessive load on the opposing limb; this causes decreased blood flow to the cells, decreasing oxygen and nutrient delivery, thus altering their metabolism which results in laminitis.
Matrix metalloproteinasesOne of the newest theories for the molecular basis of laminitis involves matrix metalloproteinases. Metalloproteinases are enzymes that can degrade collagen, growth factors, cytokines to remodel the extracellular matrix of tissues. To prevent tissue damage, they are regulated by tissue inhibitors of metalloproteinases. In cases of laminitis, an underlying cause is thought to cause an imbalance of MMPs and TIMPs, favoring MMPs, so that they may cleave substances within the extracellular matrix and therefore break down the basement membrane. Since the basement membrane is the main link between the hoof wall and the connective tissue of P3, it is thought that its destruction results in their separation. MMP-2 and MMP-9 are the primary enzymes thought to be linked to laminitis. Theories for developmentThere are multiple theories as to; these include: Enzymatic and inflammatory theories: The enzymatic theory postulates that increased blood flow to the foot brings in inflammatory cytokines or other substances to the hoof, where they increase production of MMPs, which subsequently break down the basement membrane.
The inflammatory theory states that inflammatory mediators produce inflammation, but recognizes that MMP production occurs later. Therefore, this is a 2-step process, beginning with inflammation and leading to MMP production and subsequent laminitis. Vascular theory: Postulates that increases in capillary pressure, constriction of veins, shunting of blood through anastomoses to bypass the capillaries, causes decreased blood and therefore decreased oxygen and nutrient delivery to lamellae; the end-result would be ischemia, leading to cellular breakdown between the lamellae. Subsequently, increased vascular permeability leads to edema within the hoof, compression of small vessels, ischemia. Vasoactive amines may be to blame for changes in hoof blood flow. Metabolic theory: Insulin affects multiple processes within the body, including inflammation, blood flow, tissue remodeling. Change in insulin regulation may lead to laminitis. Hyperinsulinemia has been shown to cause increase
The European roe deer known as the western roe deer, chevreuil, or roe deer or roe, is a species of deer. The male of the species is sometimes referred to as a roebuck; the roe deer is small and grey-brown, well-adapted to cold environments. The species is widespread in Europe, from the Mediterranean to Scandinavia, from Scotland to the Caucasus, east to northern Iran and Iraq, it is distinct from the somewhat larger Siberian roe deer. Within Europe, the European roe deer occurs in most areas, with the exception of northernmost Scandinavia and some of the islands, notably Iceland and the Mediterranean Sea islands. Scottish roe deer were introduced to the Lissadell Estate in Co. Sligo in Ireland around 1870 by Sir Henry Gore-Booth, Bt; the Lissadell deer were noted for their occasional abnormal antlers and survived in that general area for about 50 years before they died out. According to the National Biodiversity Data Centre, in 2014 there was a confirmed sighting of roe deer in County Armagh. There have been other, sightings in County Wicklow.
In England and Wales, roe have experienced a substantial expansion in their range in the latter half of the 20th century and continuing into the 21st century. This increase in population appears to be affecting woodland ecosystems. At the start of the 20th century, they were extinct in Southern England, but since have hugely expanded their range for no apparent reason and in some cases with human help. In 1884, roe were introduced from Württemberg in Germany into the Thetford Chase area, these spread to populate most of Norfolk and substantial parts of Cambridgeshire. In southern England, they started their expansion in Sussex and from there soon spread into Surrey, Wiltshire and Dorset, for the first half of the 20th century, most roe in southern England were to be found in these counties. By the end of the 20th century, they had repopulated much of Southern England and had expanded into Somerset, Cornwall, Gloucestershire, Warwickshire and South Yorkshire, had spread into mid-Wales from the Ludlow area where an isolated population had appeared.
At the same time, the surviving population in Scotland and the Lake District had pushed further south beyond Yorkshire and Lancashire and into Derbyshire and Humberside. Roe can now be found in most of rural England except for south east Kent and the greater part of Staffordshire and Cheshire, although the expansion is continuing to the extent that before the end of the 21st century, anywhere in the UK mainland suitable for roe may have a population. Not being a species that needs large areas of woodland to survive, urban roe are now a feature of several cities, notably Glasgow and Bristol, where in particular they favour cemeteries. In Wales, they are less common, but have been seen as far south west as Cardigan and as far north west as Bangor, they are reasonably well established in Powys and Monmouthshire. German colonial administrators introduced roe deer to the island of Pohnpei in Micronesia, they are hunted by locals in steep and vegetated terrain. The meat is sold in markets and restaurants in Kolonia, the capital city of Pohnpei and the Federated States of Micronesia.
The roe deer is distinct from the somewhat larger Siberian roe deer found from the Ural Mountains to as far east as China and Siberia. The two species meet at the Caucasus Mountains, with the European species occupying the southern flank of the mountain ranges and adjacent Asia Minor, the Siberian species occupying the northern flank of the mountain ranges, it is known. The roe deer is a small deer, with a body length of 95–135 cm, a shoulder height of 65–75 cm, a weight of 15–35 kg. Bucks in good conditions develop antlers up to 20–25 cm long with two or three even four, points; when the male's antlers begin to regrow, they are covered in a thin layer of velvet-like fur which disappears on after the hair's blood supply is lost. Males may speed up the process by rubbing their antlers on trees, so that their antlers are hard and stiff for the duels during the mating season. Unlike most cervids, roe deer begin regrowing antlers immediately after they are shed; the roe deer is crepuscular quick and graceful, lives in woods, although it may venture into grasslands and sparse forests.
They feed on grass, leaves and young shoots. They like young, tender grass with a high moisture content, i.e. grass that has received rain the day before. Roe deer will not venture into a field that has had or has livestock in it because the livestock make the grass unclean. A pioneer species associated with biotic communities at an early stage of succession, during the Neolithic period in Europe, the roe deer was abundant, taking advantage of areas of forest or woodland cleared by Neolithic farmers; the roe deer attains a maximum lifespan of 10 years. When alarmed, it will flash out its white rump patch. Rump patches differ between the sexes, with the white rump patches heart-shaped on females and kidney-shaped on males. Males may bark or make a low grunting noise. Females make a high-pitched "pheep" whine to attract males during the rut in August; the female goes looking for a mate and lures the
Domestic sheep are quadrupedal, ruminant mammals kept as livestock. Like most ruminants, sheep are members of the even-toed ungulates. Although the name sheep applies to many species in the genus Ovis, in everyday usage it always refers to Ovis aries. Numbering a little over one billion, domestic sheep are the most numerous species of sheep. An adult female sheep is referred to as a ewe, an intact male as a ram or a tup, a castrated male as a wether, a younger sheep as a lamb. Sheep are most descended from the wild mouflon of Europe and Asia. One of the earliest animals to be domesticated for agricultural purposes, sheep are raised for fleeces and milk. A sheep's wool is the most used animal fiber, is harvested by shearing. Ovine meat is called lamb when from younger animals and mutton when from older ones in Commonwealth countries, lamb in the United States. Sheep continue to be important for wool and meat today, are occasionally raised for pelts, as dairy animals, or as model organisms for science.
Sheep husbandry is practised throughout the majority of the inhabited world, has been fundamental to many civilizations. In the modern era, New Zealand, the southern and central South American nations, the British Isles are most associated with sheep production. Sheepraising has a large lexicon of unique terms which vary by region and dialect. Use of the word sheep began in Middle English as a derivation of the Old English word scēap. A group of sheep is called a herd or mob. Many other specific terms for the various life stages of sheep exist related to lambing and age. Being a key animal in the history of farming, sheep have a entrenched place in human culture, find representation in much modern language and symbology; as livestock, sheep are most associated with pastoral, Arcadian imagery. Sheep figure in many mythologies—such as the Golden Fleece—and major religions the Abrahamic traditions. In both ancient and modern religious ritual, sheep are used as sacrificial animals; the exact line of descent between domestic sheep and their wild ancestors is unclear.
The most common hypothesis states. Sheep were among the first animals to be domesticated by humankind. C in Mesopotamia; the rearing of sheep for secondary products, the resulting breed development, began in either southwest Asia or western Europe. Sheep were kept for meat and skins. Archaeological evidence from statuary found at sites in Iran suggests that selection for woolly sheep may have begun around 6000 BC, the earliest woven wool garments have been dated to two to three thousand years later. Sheep husbandry spread in Europe. Excavations show that in about 6000 BC, during the Neolithic period of prehistory, the Castelnovien people, living around Châteauneuf-les-Martigues near present-day Marseille in the south of France, were among the first in Europe to keep domestic sheep. From its inception, ancient Greek civilization relied on sheep as primary livestock, were said to name individual animals. Ancient Romans kept sheep on a wide scale, were an important agent in the spread of sheep raising.
Pliny the Elder, in his Natural History, speaks at length about wool. European colonists spread the practice to the New World from 1493 onwards. Domestic sheep are small ruminants with a crimped hair called wool and with horns forming a lateral spiral. Domestic sheep differ from their wild relatives and ancestors in several respects, having become uniquely neotenic as a result of selective breeding by humans. A few primitive breeds of sheep retain some of the characteristics of their wild cousins, such as short tails. Depending on breed, domestic sheep may have no horns at all, or horns in both sexes, or in males only. Most horned breeds have a single pair. Another trait unique to domestic sheep as compared to wild ovines is their wide variation in color. Wild sheep are variations of brown hues, variation within species is limited. Colors of domestic sheep range from pure white to dark chocolate brown, spotted or piebald. Selection for dyeable white fleeces began early in sheep domestication, as white wool is a dominant trait it spread quickly.
However, colored sheep do appear in many modern breeds, may appear as a recessive trait in white flocks. While white wool is desirable for large commercial markets, there is a niche market for colored fleeces for handspinning; the nature of the fleece varies among the breeds, from dense and crimped, to long and hairlike. There is variation of wool type and quality among members of the same flock, so wool classing is a step in the commercial processing of the fibre. Depending on breed, sheep show a range of weights, their rate of growth and mature weight is a heritable trait, selected for in breeding. Ewes weigh between 45 and 100 kilograms, rams between 45 and 160 kilograms; when all deciduous teeth have erupted, the sheep has 20 teeth. Mature sheep have 32 teeth; as with other ruminants, the front teeth in the lower jaw bite against a hard, toothless pad in the upper jaw. These are used to pick off vegetation the rear
Frog (horse anatomy)
The frog is a part of a horse's hoof, located on the underside, which should touch the ground if the horse is standing on soft footing. The frog is triangular in shape, extends mid way from the heels toward the toe, covering around 25% of the bottom of the hoof; the frog acts as a shock absorber for the foot when it makes impact with the ground, decreasing the force placed on the bones and joints of the leg. The frog is an important part of the horse's circulatory system — it pumps blood up the horse's leg each time the frog makes contact with the ground; the blood flows down the horse's leg into the digital cushion, a fibrous part of the inner hoof located just above the frog which contains a network of blood vessels. The horse's weight compresses the frog on the ground, squeezing the blood out of the digital cushion, pushing it back up the horse's legs. Therefore, farriers keep the frog as large and ground-covering as possible when they trim or shoe the feet; when a horse has certain types of lameness, the farrier may use the frog for support, using specialized shoes that help keep correct pressure on the frog so that less force is transmitted to the wall and sole of the foot or to the navicular bone, coffin bone, deep digital flexor tendon.
The frog may decrease in size if it does not receive constant pressure, which can occur if the heels of the horse become contracted. Thrush: In horses, thrush is a bacterial infection by Fusobacterium necrophorum that affects the frog, which can cause lameness in severe cases. Note that thrush in humans is an unrelated fungal infection due to Candida albicans. Equine anatomy Horse hoof Horseshoe