The skeletal system of the horse has three major functions in the body. It protects vital organs, provides framework, and supports soft parts of the body. Horses typically have 205 bones. The pelvic limb typically contains 19 bones, while the thoracic limb contains 20 bones.

Functions of bones

Bones serve three major functions in the skeletal system; they act as levers, they store minerals, and they are the site of red blood cell

Red blood cell

Red blood cells are the most common type of blood cell and the vertebrate organism's principal means of delivering oxygen to the body tissues via the blood flow through the circulatory system...

 formation. Bones can be classified into five categories

1. Long Bones
   Long bone
   The long bones are those that are longer than they are wide. They are one of five types of bones: long, short, flat, irregular and sesamoid. Long bones, especially the femur and tibia, are subjected to most of the load during daily activities and they are crucial for skeletal mobility. They grow...
   
   : aid in locomotion, store minerals, and act as levers. They are found mainly in the limbs.
2. Short Bones
   Short bone
   The patella, together with the other sesamoid bones, are by some regarded as short bones. Many short bones break more easily than large bones due to lack of support and extensive bone marrow-References:*...
   
   : Absorb concussion. Found in joints such as the knee, hock, and fetlock.
3. Flat Bones
   Flat bone
   Flat bones are those bones which are found where the principal requirement is either extensive protection or the provision of broad surfaces for muscular attachment...
   
   : Enclose body cavities containing organs. The ribs are examples of flat bones.
4. Irregular Bones
   Irregular bone
   The irregular bones are bones which, from their peculiar form, cannot be grouped as long bone, short bone, flat bone or sesamoid bone. Irregular bones serve various purposes in the body, such as protection of nervous tissue , affording multiple anchor points for skeletal muscle attachment , and...
   
   : Protect the central nervous system. The vertebral column consists of irregular bones.
5. Sesamoids: Bones embedded within a tendon. The horse's proximal digital sesamoids are simply called the "sesamoid bones" by horsemen, his distal digital sesamoid is referred to as the navicular bone
   Navicular bone
   The navicular bone is a small bone found in the feet of both humans and horses.- Human anatomy :The navicular bone is one of the tarsal bones, found in the foot. Its name derives from the bone's resemblance to a small boat, caused by the strongly concave proximal articular surface...
   
   .

Ligaments and tendons hold the skeletal system together. Ligaments hold bones to bones and tendons hold bones to muscles. Synovial membranes are found in joint capsules, where they contain synovial fluid

Synovial fluid

Synovial fluid is a viscous, non-Newtonian fluid found in the cavities of synovial joints. With its yolk-like consistency , the principal role of synovial fluid is to reduce friction between the articular cartilage of synovial joints during movement.-Overview:The inner membrane of synovial joints...

, which lubricates joints. Bones are covered by a tough membrane called periosteum, which covers the entire bone excluding areas of articulation.

Ligaments

Ligament

Ligament

In anatomy, the term ligament is used to denote any of three types of structures. Most commonly, it refers to fibrous tissue that connects bones to other bones and is also known as articular ligament, articular larua, fibrous ligament, or true ligament.Ligament can also refer to:* Peritoneal...

s attach bone to bone, and are vital in stabilizing joints as well as supporting structures. They are made up of fibrous material that is generally quite strong. Due to their relatively poor blood supply, ligament injuries generally take a long time to heal.

Ligaments of the upper body include:

• Nuchal and supraspinous ligaments: the nuchal ligament
  Nuchal ligament
  The paxwax or nuchal ligament is a fibrous membrane, which, in the neck, represents the supraspinal ligaments of the lower vertebræ...
  
   attaches to the dorsal surface of the cervical vertebrae
  Cervical vertebrae
  In vertebrates, cervical vertebrae are those vertebrae immediately inferior to the skull.Thoracic vertebrae in all mammalian species are defined as those vertebrae that also carry a pair of ribs, and lie caudal to the cervical vertebrae. Further caudally follow the lumbar vertebrae, which also...
  
  . Its dorsal section extends from the occipital protuberance of the skull (the poll) to the withers, then narrows to become the supraspinous ligament. It also connects the 2-7th cervical vertebrae to the 1-3rd thoracic vertebrae
  Thoracic vertebrae
  In human anatomy, twelve thoracic vertebrae compose the middle segment of the vertebral column, between the cervical vertebrae and the lumbar vertebrae. They are intermediate in size between those of the cervical and lumbar regions; they increase in size as one proceeds down the spine, the upper...
  
  . Its main purpose is to support the head and allow it to be moved upward or downward.
• Intercapital ligaments: lie between the first through eleventh ribs. Help to prevent thoracic disk herniation.

Ligaments of the legs include:

• Suspensory ligament: runs from the back of the cannon bone (between the two spint bones), then splits into two branches and attaches to the sesamoid bones at the bottom of the fetlock. Branches continue downward and attach to the extensor tendons. The main purpose of the suspensory is to support the fetlock joint, preventing it from overextending. Injury to this ligament is an important cause of lameness in performance horses. The suspensory is a modified muscle, the equine equivalent of the interosseous muscle, which contains both tendon fibers and residual muscle fibers..
• Interosseous ligaments: connect the cannon bone to each splint bone. Injury to this ligament produces the condition known as "splints
  Splints
  Splints is an ailment of the horse or pony, characterized by a hard, bony swelling, usually on the inside of a front leg, lying between the splint and cannon bone or on the splint bone itself. It may be "hot," meaning that it occurred recently and is still painful; or "cold," meaning that the...
  
  ".
• Proximal and distal check ligaments: The proximal check ligament originates from the radius and attaches to the superficial digital flexor tendon. The distal check originates from the palmar carpal ligament and attaches to the deep digital flexor tendon, approximately 2/3-way down the metacarpus.
• Plantar ligament: in the hind leg, runs down the lateral side of the tarsus, attaches to the fibular, 4th tarsal, and 3rd metatarsal bones. Injury leads to a condition known as "curb
  Curb
  Curb may refer to:* Curb , or kerb, the edge where a raised pavement/sidewalk/footpath, road median, or road shoulder meets an unraised street or other roadway.* Curb Records, a record label started by Mike Curb in 1973....
  
  ".
• Inter-sesamoidean ligaments: supporting ligaments, run between the two sesamoid bones.
• Distal sesamoidean ligaments: run from the sesamoid bones to the two pastern bones. Important in the stay apparatus.
• Impar ligament: runs between the navicular bone and the 3rd phalanx.
• Annular ligament: goes around the back of the fetlock, surrounding the flexor tendons and their tendon sheath, attaching to the sesamoid bones. It helps to support the fetlock, and provides an enclosed "pulley" for the flexor tendons to run through.
• Sacrosciatic ligament: Originates from the sacrum and coccygeal vertebrae, inserts into the pelvis.

Axial skeleton

The axial skeleton contains the skull

Skull

The skull is a bony structure in the head of many animals that supports the structures of the face and forms a cavity for the brain.The skull is composed of two parts: the cranium and the mandible. A skull without a mandible is only a cranium. Animals that have skulls are called craniates...

, vertebral column

Vertebral column

In human anatomy, the vertebral column is a column usually consisting of 24 articulating vertebrae, and 9 fused vertebrae in the sacrum and the coccyx. It is situated in the dorsal aspect of the torso, separated by intervertebral discs...

, sternum

Sternum

The sternum or breastbone is a long flat bony plate shaped like a capital "T" located anteriorly to the heart in the center of the thorax...

, and ribs. The sternum consists of multiple sternebrae, which fuse to form one bone, attached to the 8 "true" pairs of ribs, out of a total of 18.

The vertebral column usually contains 54 bones: 7 cervical vertebrae, including the atlas

Atlas (anatomy)

In anatomy, the atlas is the most superior cervical vertebra of the spine.It is named for the Atlas of Greek mythology, because it supports the globe of the head....

 (C1) and axis (C2) which support and help move the skull, 18 (or rarely, 19) thoracic, 5-6 lumbar, 5 sacral (which fuse together to form the sacrum), and 15-25 caudal vertebrae with an average of 18. Differences in number may occur, particularly in certain breeds. For example, some, though not all, Arabians, may have 5 lumbar vertebrae, opposed to the usual 6, 17 thoracic vertebrae (and ribs) instead of 18, and 16 or 17 caudal vertebrae instead of 18. The withers

Withers

The withers is the ridge between the shoulder blades of a four-legged animal. In many species it is the tallest point of the body, and in horses and dogs it is the standard place to measure the animal's height .-Horses:The withers in horses are formed by the dorsal spinal processes of roughly the...

 of the horse are made up by the dorsal spinal processes of the thoracic vertebrae numbers 5 to 9.

The skull consists of 34 bones and contains four cavities: the cranial cavity, the orbital cavity, oral, and the nasal cavity. The cranial cavity encloses and protects the brain and it supports several sense organs. The orbital cavitity surrounds and protects the eye. The oral cavity is a passage way into the respiratory and digestive systems. The nasal cavity leads into the respiratory system, and includes extensive paranasal sinuses. The nasal cavity contains turbinate bones that protect the mucous membrane that lines the cavity from warm inspired air. The skull consists of fourteen major bones

1. Incisive bone (premaxillary): part of the upper jaw; where the incisors attach
2. Nasal bone: covers the nasal cavity
3. Maxillary bone: a large bone that contains the roots of the molars
4. Mandible: lower portion of the jaw; largest bone in the skull
5. Lacrimal bone: contains the nasolacrimal duct, which carries fluid from the surface of the eye, to the nose
6. Frontal bone: creates the forehead of the horse
7. Parietal bone: extends from the forehead to the back of the skull
8. Occipital bone: forms the joint between the skull and the first vertebrae of the neck (the atlas)
9. Temporal bone: contains the eternal acoustic meatus, which transmits sound from the ear to the cochlea (eardrum)
10. Zygomatic bone: attaches to the temporal bone to form the zygomatic arch (cheek bone)
11. Palatine bone: forms the back of the hard palate
12. Sphenoid: formed by fusion of the foetal basisphenoid and presphenoid bones, at the base of the skull. Can become fractured in horses that rear over backwards.
13. Vomer: forms the top of the inside of the nasal cavity
14. Pterygoid: small bone attached to the sphenoid that extends downward

Appendicular skeleton

The appendicular skeleton contains the fore and hindlimbs. The hindlimb attaches to the vertebral column via the pelvis, while the forelimb does not directly attach to the spine (as a horse does not have a collar bone), and is instead suspended in place by muscles and tendons. This allows great mobility in the front limb, and is partially responsible for the horse's ability to fold his legs up when jumping. Although the hindlimb supports only about 40% of the weight of the animal, it creates most of the forward movement of the horse, and is stabilized through attachments to the spine.

Important bones and joints of the forelimb

• Scapula
  Scapula
  In anatomy, the scapula , omo, or shoulder blade, is the bone that connects the humerus with the clavicle ....
  
   (shoulder blade): flat bone with a large area of cartilage that partially forms the withers. The shoulder length and angle is very important to horsemen when evaluating conformation
  Equine conformation
  Equine conformation evaluates the degree of correctness of a horse's bone structure, musculature, and its body proportions in relation to each other. Undesirable conformation can limit the ability to perform a specific task. Although there are several universal "faults," a horse's conformation is...
  
  .
• Humerus
  Humerus
  The humerus is a long bone in the arm or forelimb that runs from the shoulder to the elbow....
  
  : lies between the scapula and the radius, making an angle of about 55 degrees down and back. (Misspelled in the picture as "Humercus")
• Radius: extends from the elbow, where it articulates with the humerus, and travels downward to the carpus. It forms the "forearm" of the horse along with the ulna.
• Ulna: caudal to the radius, it is usually partially fused to that bone in an adult horse.
• Shoulder joint (scapulohumeral joint): usually has an angle of 120-130 degrees when the horse is standing, which can extended to 145 degrees, and flexed to 80 degrees (such as when the horse is jumping and obstacle).
• Elbow joint (humeroradial joint): hinge joint that can flex 55-60 degrees.
• Carpus
  Carpus
  In tetrapods, the carpus is the sole cluster of bones in the wrist between the radius and ulna and the metacarpus. The bones of the carpus do not belong to individual fingers , whereas those of the metacarpus do. The corresponding part of the foot is the tarsus...
  
   (knee): consists of 7-8 bones placed in 2 rows to form 3 joints. The 1st carpal bone is present only 50% of the time. Which on humans is the wrist.

Important bones and joints of the hindlimb

• Pelvis: made up of the os coxae, the largest of the flat bones in a horse. It is made up of the ilium
  Ilium (bone)
  The ilium is the uppermost and largest bone of the pelvis, and appears in most vertebrates including mammals and birds, but not bony fish. All reptiles have an ilium except snakes, although some snake species have a tiny bone which is considered to be an ilium.The name comes from the Latin ,...
  
  , the ischium, and the pubis
  Pubis (bone)
  In vertebrates, the pubic bone is the ventral and anterior of the three principal bones composing either half of the pelvis.It is covered by a layer of fat, which is covered by the mons pubis....
  
  . At the junction of these three bones is a cavity called the acetabulum
  Acetabulum
  The acetabulum is a concave surface of the pelvis. The head of the femur meets with the pelvis at the acetabulum, forming the hip joint.-Structure:...
  
  , which acts as the socket of the hip joint. The pelvic cavity is larger in diameter in the mare than in the stallion, providing more room for the foal during birth.
• Femur
  Femur
  The femur , or thigh bone, is the most proximal bone of the leg in tetrapod vertebrates capable of walking or jumping, such as most land mammals, birds, many reptiles such as lizards, and amphibians such as frogs. In vertebrates with four legs such as dogs and horses, the femur is found only in...
  
  : the largest long bone in a horse. Proximally it forms a ball-and-socket joint with the pelvis to form the hip joint, and distally it meets the tibia and patella at the stifle joint. It serves as an attachment point for the deep and middle glueteal muscles, and the accessory and round ligaments.
• Patella
• Tibia
  Tibia
  The tibia , shinbone, or shankbone is the larger and stronger of the two bones in the leg below the knee in vertebrates , and connects the knee with the ankle bones....
  
  : runs from stifle to hock. The proximal end provides attachment for the patellar ligaments, meniscal ligaments, cruciate ligamnents, and collateral lligaments of the stifle. The distal end provides attachment for the collateral ligaments of the hock.
• Fibula: completely fused to the tibia in most horses.
• Hip joint : Ball-and-socket joint made up of the acetabulum of the pelvis and the femur. It is very stable.
• Stifle joint (femoropatellar joint): actually composed of three joint compartments: the femoropatellar joint, the medial femorotibial joint, and the lateral femorotibial joint, which are stabilized by a network of ligaments. The stifle has an articular angle of about 150 degrees.
• Tarsus
  Tarsus (skeleton)
  In tetrapods, the tarsus is a cluster of articulating bones in each foot situated between the lower end of tibia and fibula of the lower leg and the metatarsus. In the foot the tarsus articulates with the bones of the metatarsus, which in turn articulate with the bones of the individual toes...
  
   (hock): consists of 6 bones (of which one is made up of the fused 1st and 2nd tarsal bones) aligned in 3 rows. The largest bone in the hock, the calcaneus or fibular tarsal bone, corresponds to the human heel, and creates the tuber calcis (point of hock). It is to this point that the tendon of the gastrocnemius, portions of the biceps femoris, and portions of the superficial digital flexor attach.

Bones of the lower limb

Bones of the lower limb, present in both the front and hind legs include the cannon bone

Equine forelimb anatomy

The equine forelimb of the horse is attached to the trunk of the animal by purely muscular connections...

 (3rd metacarpal/3rd metatarsal), splint bone

Equine forelimb anatomy

The equine forelimb of the horse is attached to the trunk of the animal by purely muscular connections...

s (2nd and 4th metacarpal/metatarsal), proximal sesamoid bones, long pastern (proximal or 1st phalanx), short pastern (middle or 2nd phalanx), coffin bone

Equine forelimb anatomy

The equine forelimb of the horse is attached to the trunk of the animal by purely muscular connections...

 (distal or 3rd phalanx), and navicular bone

Navicular bone

The navicular bone is a small bone found in the feet of both humans and horses.- Human anatomy :The navicular bone is one of the tarsal bones, found in the foot. Its name derives from the bone's resemblance to a small boat, caused by the strongly concave proximal articular surface...

 (distal sesamoid). There are usually slight differences in these bones when comparing the front and the hind. The 3rd metatarsal is about 1/6 longer than the 3rd metacarpal. Similarly, the 2nd and 4th metatarsals are longer in length when compared to their front-end counterpart. In the hindlimb, the 1st phalanx is shorter and the 2nd phalanx is longer than in the frontlimb. In addition, the 2nd and 3rd phalanx are narrower in the hind limb. The angle created by these three bones in the hindleg is steeper by about 5 degrees, therefore making the pastern

Pastern

The pastern is a part of the leg of a horse between the fetlock and the top of the hoof. It incorporates the long pastern bone and the short pastern bone , which are held together by two sets of paired ligaments to form the pastern joint...

 angle steeper behind than in front.

Skeletal system disorders

• Arthritis (horse)
  • Degenerative joint disease (DJD), such as bone spavin
    Bone spavin
    Bone spavin is a bony growth within the lower hock joint of horse or cattle. It is caused by osteoarthritis, and the degree of lameness that results can be serious enough to end a horse's competitive career.-Description of bone spavin:...
    
    , ringbone
    Ringbone
    Ringbone is exostosis in the pastern or coffin joint of a horse. In severe cases, the growth can encircle the bones, giving ringbone its name...
    
    , omarthritis
  • Inflammatory joint disease such as Carpitis (sprained knee), osselets
• Bucked shins
• Curb
  Curb (horse)
  Curb is defined in older literature as enlargement secondary to inflammation and thickening of the long plantar ligament in horses. However, with the widespread use of diagnostic ultrasonography in equine medicine, curb has been redefined as a collection of soft tissue injuries of the distal...
  
  
• Degenerative suspensory ligament desmitis (DSLD), and sprains of the suspensory ligament
• Fractures
• Locked kneecap (delayed patellar release or intermittent upward fixation of the patella)
• Navicular disease
  Navicular Disease
  Navicular Disease is a soundness problem in horses, more accurately called "navicular syndrome" as opposed to "disease." It most commonly describes an inflammation or degeneration of the navicular bone and its surrounding tissues, usually on the front feet...
  
  
• Osteochondrosis (horse)
• Sesamoiditis
• Splints
  Splints
  Splints is an ailment of the horse or pony, characterized by a hard, bony swelling, usually on the inside of a front leg, lying between the splint and cannon bone or on the splint bone itself. It may be "hot," meaning that it occurred recently and is still painful; or "cold," meaning that the...
  
  

Joint issues

Performance horses, like human athletes, place a high amount of stress on their bones and joints. This is especially true if the horse jumps, gallops, or performs sudden turns or changes of pace, as can be seen in racehorses, show jumpers, eventers, polo ponies, reiners, and western performance horses. A high percentage of performance horses develop arthritis, especially if they are worked intensely when young or are worked on poor footing.

One of the goals for management for these horses often involve caring for the joints to reduce the progression of arthritis. This usually includes a close monitoring of the animal's schedule to determine how to reduce the amount of joint concussion he experiences. Examples of this tactic include reducing the number of days the horse jumps to the absolute minimum to still keep him at optimum performance, altering the conditioning schedule so that the horse is not worked on extremely hard ground, and conditioning and training the horse in such a way that he "peaks" before a competition rather than keeping him in intense work year-round. This tactic can help increase the useful working life of the horse.

Joint medications

In addition, most owners usually augment this good management with proper nutrition, joint supplements, and joint injections. Commonly used substance are listed below. It is important for owners to check with their various equestrian organizations to be sure that the substances they use are not banned from competition, as they will have to plan their administration schedule around the animal's competitive career.

Hyaluronic Acid/Sodium hyaluronate

Hyaluronic acid (HA) naturally occurs, and is identical, in all animals. It is made by chondrocytes and the synovial lining of a joint, and being an unsulfonated glycosaminoglycan, it is a type of proteoglycan

Proteoglycan

Proteoglycans are proteins that are heavily glycosylated. The basic proteoglycan unit consists of a "core protein" with one or more covalently attached glycosaminoglycan chain. The point of attachment is a Ser residue to which the glycosaminoglycan is joined through a tetrasaccharide bridge...

 (chemicals that make up cartilage, the synovial lining, and joint fluid). HA helps to alleviate arthritis by reducing inflammation within the joint, allowing it to produce better synovial fluid, and may help to heal the joint by supporting the connective tissue. HA was originally injected into the joint of the horse, but one product is labeled for intravenous use. Before injecting intra-articularly, some veterinarians drain some of the excess joint fluid.

Although HA may be expensive, it is considered very safe to use and it has proven to be a very successful drug.

Brand names include Legend, Hyalovet

Polysulfated glycosaminoglycans

Polysulfated glycosaminoglycan

Glycosaminoglycan

Glycosaminoglycans or mucopolysaccharides are long unbranched polysaccharides consisting of a repeating disaccharide unit. The repeating unit consists of a hexose or a hexuronic acid, linked to a hexosamine .-Production:Protein cores made in the rough endoplasmic reticulum are posttranslationally...

s (PSGAGs) may be injected either intra-muscularly or intra-articularly, although they should not be used within infected joints. PSGAGs are chemically similar to the main component of joint fluid and cartilage—glycosaminoglycans (GAGs)—and are also thought to reduce the inflammation in the joint, as well as protect the cartilage. This occurs because PSGAGs inhibit prostaglandin

Prostaglandin

A prostaglandin is any member of a group of lipid compounds that are derived enzymatically from fatty acids and have important functions in the animal body. Every prostaglandin contains 20 carbon atoms, including a 5-carbon ring....

 as well as the enzymes which destroy cartilage, and also have anti-inflammatory effects. In addition, polysulfated glycosaminoglycan restores the synovial fluid

Synovial fluid

Synovial fluid is a viscous, non-Newtonian fluid found in the cavities of synovial joints. With its yolk-like consistency , the principal role of synovial fluid is to reduce friction between the articular cartilage of synovial joints during movement.-Overview:The inner membrane of synovial joints...

, which acts as a lubricant to enhance joint movement.

After IM injection, PSGAGs take 2 hours to move into all tissues and are at their highest levels 48 hours following IM injection, but last for 72 hours. Although they move into all tissues within the horse, they are found in highest concentrations in inflamed joints.

Examples of PSGAGs include Adequan and Chondroprotec.

Corticosteroids

Corticosteroid

Corticosteroid

Corticosteroids are a class of steroid hormones that are produced in the adrenal cortex. Corticosteroids are involved in a wide range of physiologic systems such as stress response, immune response and regulation of inflammation, carbohydrate metabolism, protein catabolism, blood electrolyte...

s (glucocorticoids) are naturally produced by the adrenal gland

Adrenal gland

In mammals, the adrenal glands are endocrine glands that sit atop the kidneys; in humans, the right suprarenal gland is triangular shaped, while the left suprarenal gland is semilunar shaped...

 to control metabolism, as well as reduce inflammation. The latter effect is the main reason they are used in the joints: intra-articular injections of corticosteroids decrease the inflammation associated with arthritis, partially by reducing the production of prostaglandin. Additionally, it is thought that they may increase the production of glucose, although this is still debated by veterinarians.

Corticosteroids can have very bad side effects if given chronically. Additionally, injections within the joint will still "leak" corticosteroids into the surrounding tissues and circulate throughout the body. It is therefore best to perform radiographs of the intended joint beforehand, and have a qualified veterinarian assist in determining the proper dosages for the horse. Possible side effects include a decrease of immune response within the injected joint (which makes it more likely to infection), laminitis

Laminitis

Laminitis is a disease that affects the feet of ungulates. It is best known in horses and cattle. Symptoms include lameness, and increased temperature in the hooves...

, and suppression of natural production of corticosteroids by the horse. Additionally, they should not be used in horses with Cushing's disease.

Corticosteroids are banned in certain circumstances from use by many equestrian organizations, partially because they can change the animal's temperament.

Nutraceuticals and oral joint supplements

Many owners supplement their joint health program by feeding supplements containing various nutraceutical

Nutraceutical

Nutraceutical, a portmanteau of the words “nutrition” and “pharmaceutical”, is a food or food product that reportedly provides health and medical benefits, including the prevention and treatment of disease. Health Canada defines the term as "a product isolated or purified from foods that is...

 substances which are thought to benefit the joint, including oral glycosaminoglycans (glucosamine

Glucosamine

Glucosamine is an amino sugar and a prominent precursor in the biochemical synthesis of glycosylated proteins and lipids. Glucosamine is part of the structure of the polysaccharides chitosan and chitin, which compose the exoskeletons of crustaceans and other arthropods, cell walls in fungi and...

 and chondroitin sulfate

Chondroitin sulfate

Chondroitin sulfate is a sulfated glycosaminoglycan composed of a chain of alternating sugars . It is usually found attached to proteins as part of a proteoglycan. A chondroitin chain can have over 100 individual sugars, each of which can be sulfated in variable positions and quantities...

), methylsulfonylmethane

Methylsulfonylmethane

Methylsulfonylmethane is an organosulfur compound with the formula 2SO2. It is also known by several other names including DMSO2, methyl sulfone, and dimethyl sulfone. This colorless solid features the sulfonyl functional group and is considered relatively inert chemically...

 (MSM), and, most recently, hyaluronic acid (HA). Effectiveness of these substances in oral form is hotly debated. On one side, a number of consumer-based tests suggest they can be effective. Many anecdotal reports testify to the effectiveness of various formulas, particularly those with high dosages of glucosamine. On the other side, organizations such as the American Association of Equine Practitioners (AAEP) point out that very few independent studies using a truly scientific model have been performed on oral joint supplements, and thus, the extent of their positive effects is debatable. Because nutraceuticals are not regulated by the U.S. Food and Drug Administration, there are also considerable tremendous variations in quality from one manufacturer to another.
e

Omega 3 fatty acids

Omega 3 fatty acids, used in the past to improve hair coat shine, have recently become popular for use in horses as a way to reduce joint inflammation. They are added as oral supplements into the horse's diet, most commonly as ground flaxseed, or commercially-prepared products based on flaxseed and containing other ingredients, particularly rice bran. Studies are currently underway to determine effectiveness.

NSAIDs

Non-steroidal anti-inflammatory drug

Non-steroidal anti-inflammatory drug

Nonsteroidal anti-inflammatory drugs, usually abbreviated to NSAIDs or NAIDs, but also referred to as nonsteroidal anti-inflammatory agents/analgesics or nonsteroidal Anti-inflammatory medicines , are drugs with analgesic and antipyretic effects and which have, in higher doses, anti-inflammatory...

s (NSAIDs) help to reduce inflammation by inhibiting prostaglandins and other chemicals, and also provide pain relief. However, they do not cure the underlying problem or speed the rate of recovery, and can therefore mask potential problems. Owners should not keep their horses on prolonged NSAID use without the permission of their vet, due to serious side-effects. It is therefore not to be used as a "daily supplement."

Phenylbutazone

Phenylbutazone

Phenylbutazone, often referred to as bute, is a non-steroidal anti-inflammatory drug for the short-term treatment of pain and fever in animals. In the United States, it is no longer approved for human use.-In humans:...

("bute") is one of the most common NSAIDs given for joint pain.