Category: Glossary

Hot-blooded is a classification applied to horse breeds characterized by high energy levels, heightened sensitivity to stimuli, speed, and physical refinement. The term originates in the centuries-old practice of classifying horses by their breeding heritage and associated temperament. It refers to the horse's disposition and genetic heritage, not to its actual body temperature. Hot-blooded horses were developed in hot, arid climates and have been selectively bred for speed and endurance over cold or draft power.

Primary Hot-Blooded Breeds

• Arabian: The archetype of the hot-blooded horse; developed on the Arabian Peninsula and considered the foundation of most other hot-blooded breeds. See Arabian breed profile.
• Thoroughbred: Developed in England from Arabian, Turkoman, and Barb foundation sires crossed with native English mares. The world's racing standard. See Thoroughbred breed profile.
• Akhal-Teke: An ancient Central Asian breed from Turkmenistan, renowned for its metallic coat sheen, extreme endurance, and athletic ability over long desert distances.
• Barb: A North African breed that contributed to Thoroughbred foundation and to Iberian breeds; hardy, high-energy, and fast over short distances.

Characteristics

Hot-blooded horses are typically lean and refined in build, with thin skin that allows superficial blood vessels to show during exertion. They have a high stride frequency and efficient aerobic metabolism suited to speed and sustained effort. Their sensitivity makes them highly responsive to skilled riding and potentially challenging for inexperienced handlers. They are generally not recommended as beginner horses.

The Three Blood Classifications

Horse breeds are traditionally divided into three temperature-based categories:

• Hot-blooded: High energy, refined, speed-oriented. Arabian, Thoroughbred, Akhal-Teke.
• Cold-blooded: Heavy, calm, draft-oriented. Clydesdale, Shire, Belgian. See cold-blood.
• Warm-blooded: Sport horses combining draft substance and hot-blood refinement. KWPN, Hanoverian, Oldenburg, Trakehner. See warm-blood.

In foal is the standard equine term for a pregnant mare. The phrase appears in sales listings, breeding records, and veterinary documentation as confirmation that a mare is carrying a developing foal. A mare is confirmed in foal by a veterinary examination that may include rectal palpation, transrectal ultrasound (the most common modern method), or blood/urine hormone testing. Ultrasound confirmation is typically possible by day 14 to 16 after ovulation; a heartbeat is visible by day 25 to 28.

Gestation Length

The average equine gestation period is 340 days (approximately 11 months), with a normal range of 320 to 360 days. Individual mares tend toward consistent gestations. Foals born before day 300 are premature and have significantly reduced survival rates without intensive veterinary care. Foals born between days 300 and 320 are premature to early-term and may require additional support. The foaling season in the Northern Hemisphere is typically February through June, as horses are seasonally polyestrous and naturally cycle in spring.

In Foal in Sales Listings

A mare listed for sale as in foal to [stallion name] is being sold with a confirmed pregnancy. This is a significant value factor: the buyer receives both the mare and a foal due in the next breeding season, plus the stud fee (already paid) is effectively included in the purchase price. The listing should specify: the stallion name, breeding date or confirmed pregnancy date, the method of confirmation (ultrasound is standard), the number of days of gestation at time of sale, and whether a live foal guarantee applies. Buyers should verify the pregnancy independently via veterinary examination before completing the purchase.

Care of the In-Foal Mare

Nutritional needs increase significantly in the final trimester (months 9-11), when 80% of fetal growth occurs. Mares in late pregnancy require increased digestible energy, protein (especially lysine), calcium, phosphorus, and vitamin E. Vaccination and deworming protocols for in-foal mares follow specific timing restrictions; consult a veterinarian before administering any product to a pregnant mare. Exercise continues to be beneficial through late pregnancy unless complications arise.

See also: dam; foal; at stud; selective breeding.

At stud is a phrase used to describe a stallion that has been retired from racing or competition and is now available for breeding service. A stallion stands at stud at a breeding farm or stud farm that manages bookings, collects semen, arranges breedings with visiting mares, and handles the associated logistics. The phrase appears in breed registries, sales catalogs, bloodline research, and marketplace listings as a standard descriptor of a stallion's current status and purpose.

Types of Breeding Service

• Live cover (natural service): The mare is transported to the stallion's location and bred directly. Required by some breed registries, including the Jockey Club for Thoroughbreds. Produces 100% of registered Thoroughbred foals.
• Cooled shipped semen (AI): Semen is collected, extended in a cooling medium, and shipped overnight to the mare's location for artificial insemination within 24-48 hours. Accepted by most registries except Thoroughbred. More convenient for mare owners; allows geographic access to distant stallions.
• Frozen semen: Semen is cryogenically preserved and stored indefinitely. Allows use of a stallion's genetics after death. Accepted by many registries; conception rates are typically lower than fresh or cooled semen.

Stud Fees

A stud fee is the charge for one breeding season or one confirmed pregnancy (live foal guarantee) with a specific stallion. Fees range from under $500 for local pleasure-horse stallions to over $300,000 for elite Thoroughbred sires at major breeding farms. Most stud fees are quoted as either a flat service fee (payable at breeding) or a live foal guarantee (payable when the mare produces a live, standing foal). The fee reflects the stallion's own performance record, the earnings and quality of his offspring, and market demand for his bloodlines.

See also: stallion; sire; dam; in foal.

In equestrian terminology, a schoolmaster is a horse that has been trained to a high level in a specific discipline and is used specifically to teach a less experienced rider that same discipline. The schoolmaster's value is that it already knows the job: it carries the muscle memory, the conditioned responses, and the established way of going that allows a developing rider to feel the correct movements, responses, and timing that would otherwise take years to develop on an untrained horse.

Where the Term Is Used

The term is most common in dressage, where a horse trained to Prix St. Georges level or above can allow a lower-level rider to feel half-passes, flying changes, piaffe, and passage that would be impossible to ride on a horse that has not been trained to those movements. In show jumping, a schoolmaster is a horse with experience over difficult courses that allows a junior or developing rider to learn the approach, distances, and rhythm required at height. In eventing, a schoolmaster is a horse with cross-country mileage that allows a novice event rider to learn water, ditches, banks, and combination fences safely.

Characteristics of a Good Schoolmaster

A schoolmaster must combine high-level training with a patient, forgiving temperament. A horse trained to Grand Prix dressage that is tense, reactive, or punishing to rider error is not a schoolmaster, it is a difficult horse. The ideal schoolmaster accepts the aids of a novice rider calmly, performs the movements it knows in response to correct aids (teaching the rider what correct feels like), and tolerates the inevitable errors of a developing rider without escalating. Age is typically an asset: a horse in its late teens that has competed successfully at high level and whose competitive career is winding down is often the ideal schoolmaster, combining deep muscle memory with reduced reactivity.

Price

Schoolmasters command a premium: a Grand Prix dressage schoolmaster capable of teaching flying changes and piaffe may sell for $30,000 to $150,000 or more, despite being past competitive prime, because the teaching value is real and the supply of suitable horses is limited. For jumping, an experienced Preliminary or Intermediate event horse in its mid-teens may sell for $10,000 to $40,000 as a schoolmaster after its competitive career ends.

See also: green-broke (the beginning of the training spectrum); Thoroughbred (OTTB) for a common source of affordable schoolmasters in jumping and eventing.

In horse training terminology, green-broke describes a horse that has received only the initial, most basic training under saddle or in harness. A green-broke horse accepts a rider or driver and will walk, trot, and sometimes canter on request, but it has not been consistently schooled across different environments, does not reliably respond to aids, and is likely to be unpredictable in novel situations such as traffic, water crossings, crowds, or unusual objects. The term derives from the older usage of breaking a horse to accept training, a phrase now often replaced by starting in horsemanship circles that emphasize pressure-and-release methods over force.

What Green-Broke Means in Practice

A green-broke horse has typically experienced: being saddled and accepting a rider's weight; basic forward movement at walk and trot on a familiar surface; rudimentary steering and stopping from light rein contact. It has not experienced: consistent work across varied environments; refined response to leg, seat, and rein aids; exposure to common trail or arena hazards; or the miles and repetition that build reliable behavior. The number of rides defining “green-broke” varies by seller; a horse with 20 rides and a horse with 60 rides can both be described as green-broke. Buyers should ask specifically how many rides, by whom, in what environments, and over what time period.

Green-Broke vs. Other Training Levels

• Unstarted (unbroke): No rides; has been handled on the ground but not ridden.
• Green-broke: Initial rides only; basic acceptance of a rider or driver; unpredictable outside familiar conditions.
• Lightly started: 30-90 days of consistent work; beginning to respond to aids; still developing.
• Finished: Fully trained in a specific discipline; reliable, consistent, appropriate for its intended use.
• Schoolmaster: Experienced horse that has been highly trained in a discipline and can teach a less experienced rider. See schoolmaster.

A green-broke horse is appropriate for experienced riders who have the time and skill to continue its education. It is not appropriate for novice or beginner riders, who need a predictable, well-schooled mount. The price gap between a green-broke and a finished horse reflects this difference: the training investment required to finish a green horse adds significant value.

OTTB is an acronym for Off-Track Thoroughbred: a registered Thoroughbred horse that has retired from racing and is being transitioned to a new career or home. The term is widely used in equine rescue, retraining, and competitive circles in North America, the United Kingdom, and Australia, wherever Thoroughbred racing operates at scale.

The United States retires approximately 25,000 racehorses per year. Most are OTTBs, though the category also includes horses that never raced (failed-to-start, breeding stock) but were raised and trained in a racing environment. OTTBs typically become available between ages three and seven, as the prime racing years end, though some older horses retire after longer careers at smaller tracks.

Why OTTBs Are Valued

A sound, well-conformed OTTB between four and eight years old represents substantial athletic value: it is already broke to ride, accustomed to bathing, clipping, shoeing, trailering, and handling, and has logged significant cardiovascular conditioning. Its price at the point of retirement, often $500 to $3,000, reflects the volume of horses entering the market, not their intrinsic worth as athletes. Many OTTBs go on to successful second careers in three-day eventing, show jumping, dressage, fox hunting, polo, and trail riding. The Retired Racehorse Project's Thoroughbred Makeover, held annually at the Kentucky Horse Park, showcases OTTBs competing across 18 disciplines after a 10-month retraining window.

Retraining Considerations

The transition from racing to a pleasure or sport horse career requires adjustment. OTTBs have been conditioned to gallop in company and to respond to race-specific cues. They must learn to accept contact and collection, slow gaits for trail or flatwork, and a calmer stable routine. Most experienced OTTB adopters describe a 60-to-90-day settling period before the horse stabilizes in its new environment. Organizations including the Thoroughbred Aftercare Alliance (TAA), CANTER USA, and New Vocations vet, retrain, and place OTTBs. See also the full Thoroughbred breed profile for health considerations specific to retired racehorses.

Further Reading: Thoroughbred Aftercare Alliance (TAA): accrediting body for OTTB adoption organizations. Retired Racehorse Project.

A Coggins test is a serological blood test used in horses to detect the presence of antibodies to Equine Infectious Anemia (EIA), a potentially fatal viral disease caused by a lentivirus in the same family as HIV. The test was developed by Dr. Leroy Coggins in the early 1970s, and his name has become the colloquial term for both the test and the official EIA test certificate it generates.

EIA has no approved vaccine and no cure. Infected horses may show acute signs (fever, anemia, weakness, edema) or remain as asymptomatic carriers capable of transmitting the virus to other horses via blood-feeding insects, primarily horseflies and deerflies. Because carriers show no clinical signs yet remain infectious for life, blood testing is the only way to identify them.

Legal Requirements

A negative Coggins test result is legally required for interstate transport of horses in the United States under USDA regulations, and individually by most states for intrastate movement to shows, competitions, trail rides, sales, or boarding facilities. Most equine events require a negative result dated within 12 months (some within 6 months). The official test uses the agar gel immunodiffusion (AGID) method; a competitive ELISA (cELISA) is approved as a screening test. Testing is performed by accredited veterinarians who collect a blood sample and submit it to a USDA-approved laboratory. Results are documented on a federally-approved certificate issued in the horse’s name and with identifying markings.

What a Positive Result Means

A horse that tests positive for EIA antibodies must by law be permanently identified (lip tattoo or microchip), quarantined from other horses, or euthanized. Sale of an EIA-positive horse without disclosure is a federal offense. The horse cannot be moved across state lines. Positive horses are reported to USDA APHIS, which maintains a national EIA database.

Further Reading: USDA APHIS Equine Infectious Anemia program.

Lameness is the clinical term for any alteration in a horse’s normal gait caused by pain, mechanical restriction, or neurological dysfunction originating in the limbs or feet. It is one of the most common reasons horses are removed from work and presented to veterinarians, and it encompasses a wide spectrum of conditions ranging from minor soft-tissue soreness to structural disease of bone and joint. The degree of lameness is graded on standardized scales, the American Association of Equine Practitioners grades from 0 (no detectable lameness) to 5 (non-weight-bearing), which allows consistent communication between clinicians and owners about severity and progression.

The hoof and pastern region account for the majority of forelimb lameness cases; in hindlimb cases, the hock is among the most commonly affected structures. A trained observer can detect forelimb lameness by watching the horse’s head: the head drops when the sound limb bears weight and rises when the lame limb contacts the ground. Hindlimb lameness is assessed by observing hip asymmetry during the trot. Flexion tests, hoof testers, nerve blocks, and imaging, including radiography, ultrasonography, and scintigraphy, are used in systematic lameness examination to localize the source.

Common underlying causes include laminitis, a hoof abscess, arthritis of the coffin or fetlock joint, navicular disease, soft-tissue injuries to tendons and ligaments, and fractures. The fetlock and cannon bone area are frequent sites of strain-related lameness in performance horses. Management depends entirely on the diagnosis: rest and anti-inflammatory medication suffice for many soft-tissue conditions, whereas structural joint disease may require intra-articular therapy, corrective shoeing, or surgical intervention. Early detection, guided by regular observation and consistent movement assessment, significantly improves prognosis across most lameness conditions.

Further Reading

• equine lameness (Wikipedia)
• For the clinical examination and differential diagnosis framework: overview of lameness in horses: Merck Veterinary Manual

Lice are small, wingless, dorsoventrally flattened insects of the order Phthiraptera that live their entire life cycle on the body surface of a host animal, feeding on skin debris, secretions, or blood depending on species. In horses, infestation with lice (pediculosis) is most common during winter and early spring when horses are kept in close contact, have longer coats, and reduced grooming. Heavy infestations cause intense pruritus (itching), hair loss, skin irritation, and restlessness, and can lead to weight loss in severe cases due to the metabolic cost of chronic stress and reduced feed intake.

Two species primarily infest horses: Damalinia equi (also called Werneckiella equi), a biting or chewing louse that feeds on skin scales and debris, and Haematopinus asini, a sucking louse that pierces the skin to feed on blood. The biting louse is more common and is found in the mane, forelock, tail base, and along the topline; the sucking louse favors the head, neck, and inner legs where skin is thinner. Both species attach their eggs (nits) firmly to individual hair shafts, distinguishing an active infestation from simple debris or dandruff. The mane and forelock should be checked during routine grooming by parting the hair and inspecting the skin surface.

Lice are host-specific and do not infest humans, so the zoonotic risk is negligible, but lice spread readily between horses through direct contact or shared grooming equipment, blankets, and tack. Diagnosis is by direct visualization; lice and nits are visible to the naked eye on close inspection. Treatment involves topical insecticides (pyrethrin, permethrin, or organophosphate-based products), applied twice fourteen days apart to catch eggs that were not killed by the first treatment. All horses in contact should be treated simultaneously. New horse owners should include a lice check in their quarantine protocol alongside a fecal parasite baseline and vaccination review.

Further Reading

• louse (Wikipedia)
• For diagnosis, treatment, and prevention of equine pediculosis: lice of horses: Merck Veterinary Manual

Laminitis is an inflammatory condition of the sensitive laminae, the interdigitating tissue layers that bond the coffin bone to the inner hoof wall inside the hoof capsule. When blood flow to the laminae is disrupted or overwhelmed, the tissue becomes ischemic, inflamed, and structurally weakened. In severe cases the coffin bone loses its lamellar attachment and rotates or sinks within the hoof capsule, a condition called founder. Laminitis is one of the most serious and potentially career-ending conditions in horses and is a leading cause of equine euthanasia when severe rotation occurs.

The condition most commonly affects the forefeet, which bear approximately 60 percent of the horse’s body weight, though all four feet can be involved. Acute episodes present as intense pain in the feet, the horse adopts a characteristic “sawhorse” stance, shifting weight back onto the hindlimbs to relieve pressure on inflamed forefeet, and is reluctant to move or turn. The digital pulse at the pastern and fetlock region is often bounding and elevated. The frog may feel warm compared to surrounding structures. Diagnosis is confirmed by clinical signs, hoof tester response, and radiographs showing the degree of coffin bone displacement relative to the hoof wall.

Triggers include excessive carbohydrate intake from lush pasture or grain overload, systemic illness such as colitis or retained placenta, Equine Metabolic Syndrome, Pituitary Pars Intermedia Dysfunction (PPID), prolonged weight-bearing on a contralateral limb due to an existing soundness problem, and administration of certain corticosteroids. Management in the acute phase centers on removing the inciting cause, strict box rest on deep soft bedding, cold therapy applied to the feet, and non-steroidal anti-inflammatory medication. Long-term management involves a skilled therapeutic farrier to realign the coffin bone and redistribute load, dietary restriction of soluble carbohydrates, and regular radiographic monitoring. Horses on pasture prone to laminitis should have body condition assessed regularly, as obesity is a major predisposing factor.

Further Reading

• laminitis (Wikipedia)
• For pathophysiology, grading, and treatment of equine laminitis: laminitis in horses: Merck Veterinary Manual