Allele

A version of a gene. Each gene may have several different possible versions. New versions are created when a mutation occurs in an existing allele. In genes that are not on sex chromosomes, one allele for each locus is inherited separately from each parent.

Artificial Insemination

A breeding where the sperm is collected from the male and manually inserted in a female.

Autosomal

Pertaining to any chromosome that is not a sex chromosome. A trait or disease that is autosomal (inherited on the autosomes) will affect males and females equally.

Autosome

A chromosome that is not a sex chromosome.

Backcross

Breeding a crossbred animal back to a purebred animal that is the same breed as one of the crossbred animal's parents. For example, breeding a Morab to an Arabian.

Bilateral Cryptorchid

Male that has retained a single testicle.

Breed

Classically breed is defined as a group of animals which has common ancestors, and through selection has developed consistent, distinguishable traits. However defining when a group becomes an actual breed is much more vague.

Breeding Terms

Generally referred to the terms which are placed in an agreement when a stallion/mare is sold for breeding purposes.

Broodmare

A female horse used for breeding purposes.

Chromosomes

The self-replicating genetic structures of cells containing the cellular DNA that bears in its nucleotide sequence the linear array of genes.

Coefficient Of Inbreeding

This is a measure of how likely an individual is to have both alleles for any given gene be identical and inherited from a single common ancestor. It is expressed as a percent.

Coggins Test

Test for detecting Equine Infectious Anemia.

COI

Coefficient of Inbreeding.

Colt

A male horse under four years of age.

Conformation

The overall form and structure of the horse. In the In-Hand/Halter classes at a show, the judge will examine each horse and make his decision as to which one comes closest to the breed standard.

Cowhocked

A cow-hocked horse will have hocks that turn in while causing the toes and stifles to face outward.

Crabbing

A type of movement when the horse moves his body at an angle, not straight on in the line of travel. Some will refer to this as side winding.

Crossbred

The progeny of a mating between animals from two different breeds.

Cryptorchid

This is used to describe an adult male horse that hasn't had both testicles drop into the scrotum. The retained testicle can often be found in the flank, the thigh or even up inside the abdomen.

Culling

The removal of inferior specimens from the breeding pool, through sterilization or other means.

Dam

A horse's mother.

Dock

a) To shorten a horse's tail by cutting off a portion. b) The base of the tail.

Dominant

A mutation is said to be dominant if it expresses its phenotype even when paired with an alternate allele.

Epistatic

The ability of a gene to suppress the action of another gene. The E locus can suppress the action of the A and K loci. A and K are hypostatic to E.

Equine Infectious Anemia

EIA is a viral disease spread by horseflies for which there is no vaccine and no cure. Most horses that contract this disease die, however some live and are asymptomatic carriers. Prior to the availability of testing, thousands of horses died each year from EIA.

Eumelanin

One of two major forms of pigment found in hair and skin. Normally very dark brown, the eumelanin can produce varying shades from pale cream to black depending on how it is modified. In horses, dogs, and people for example (as well as other species,) the wild type E allele must be present to have eumelanin in the hair.

False Pregnancy

A condition where the mare may show many of the signs of pregnancy, including milk production, but does not actually produce a foal.

Feathering

Long fringes of hair on the legs of some horses.

Filly

A female horse under four years of age.

Flank

The hollowed out looking area between the last rib and the hipbone.

Foal

A young horse of either gender that is under one year of age.

Foaling

The procedure during which a mare gives birth

Gait

The movement of a horse at various rates of speed. A judge watching the gait will be looking for patterns in the footsteps and leg movements during each speed observed.

Gene

A segment of DNA consisting of hundreds or thousands of base pairs that controls the production of a protein. An unit of inheritance that controls a characteristic.

Genetic

Traits that are inherited by a combination of genes from the horse's parents.

Genetic Diversity

A population is regarded as genetically diverse if a substantial proportion of the genes are polymorphic. A polymorphic gene is one for which the most common allele has a frequency of less than 0.95.

Genotype

The genetic constitution of an organism. See phenotype.

Gestation

The period of pregnancy. In horses, the average gestational period is eleven months with the normal range being ten to thirteen months.

Grade

A horse that is not eligible for registration. Horses whose parentage is unknown, are from unregistered parents, are purebred but unregsiterable, or that are not purebred.

Grading

Mating of purebred males of a given breed to non-purebred females, and the resultant female offspring in successive generations.

Heat

A female horse's estrus cycle during which time she may be bred. Influenced by length of daylight hours.

Heterozygous

Containing two different alleles of the same gene. See homozygous.

Hindquarters

The entire rear area of the horse including the pelvis, thighs, hocks, pasterns, and back feet.

Hock

The collection of bones in the rear leg that form the joint between the second thigh and the metatarsus.

Homozygous

Containing two copies of the same allele at the same gene. See heterozygous.

Inbred Line

Line of animals produced by mating related animals.

Inbreeding

Mating of animals more closely related to each other than the average relationship within the breed or population concerned.

Incross

Progeny resulting from the mating of animals from different inbred lines within a breed.

Incrossbred

Progeny resulting from the mating of animals from inbred lines of different breeds.

Lethal White Overo Syndrome

A genetic condition caused by being homozygous for the Frame Overo allele in which the foal's intestines do not properly function resulting in the death of the foal. This condition is 100% fatal.

Linebreeding

Method of breeding in which one crosses animals that are related to one specific common ancestor.

Loci

Plural form of locus.

Locus

Location (of a gene or mutation) on a chromosome.

Mare

A female horse over four years of age.

Monorchid

A male that has developed only one testicle.

Outbreeding

Mating of animals less closely related to each other than the average relationship within the breed or population concerned.

Outcross

Mating of two unrelated animals, usually within a breed.

Parrot mouth

A greatly overshot bite.

Pedigree

It is a written record of the horse's parents, grandparents and so forth (a family tree) for a minimum of three generations.

Phaeomelanin

One of two major form of pigment found in hair and skin. Normally yellow or red, the phaeomelanin can produce varying shades from pale cream to nearly black depending on how it is modified. In horses, dogs, and people for example (as well as other species,) the e allele mutation in homozygous form will prevent eumelanin from entering the hair shaft.

Phenotype

The physical appearance/observable characteristics of an organism. See genotype.

Points

The points of a horse are the legs, mane, tail, and edges of the ears.

Polygenetic

Traits which are caused by the interaction of more than one gene.

Purebred

A horse whose parents are of the same breed.

Purse

The money offered as prizes at an event. The total purse is often divided among the top finishers in the event or in each class/race of a multiple class/race event.

Reabsorption

The process where the pregnant mare may absorb fetus(es) back into her body, possibly due to deformity of the fetus, disease or stress.

Recessive

A mutation that is expressed only when it is present in two copies, or if the other copy is missing. See dominant.

Sex Chromosome

Chromosomes that determine the sex of the organism. In horses they have a single pair of chromosomes which are the XX/XY system. Females have two X chromosomes while males have one X and one Y chromosome. X chromosomes are different in size and shape than Y chromosomes.

Sex-linked

A trait that is linked to the sex of the organism due to being inherited on either the X or the Y chromosome. In horses Factor VIII/Hemophilia A is inherited on the X chromosome. The X Factor (large hearts) is theorized to be inherited on the X chromosome.

Sire

Father of a foal.

Spotting Characteristics

Horses that are Spotted have common characteristics caused by the Leopard Complex gene. These characteristics include white sclera, striped or depigmented hooves, mottled or depigmented skin.

Stallion

A male horse over four years of age.

Stifle

The knee, the joint between the first and second thigh on the hindleg.

Structure

The physical construction of a horse. May vary from breed to breed.

Stud

A facility at which horses are kept for breeding purposes

Stud Service

The use of a male for breeding purposes usually for renumeration.

Topcross

Progeny resulting from the mating of animals belonging to different family lines within a breed.

Topcrossbred

Progeny resulting from the mating of inbred males to non-inbred females of another breed.

Topincross

Progeny resulting from the mating of inbred males to non-inbred females of the same breed.

Two-breed Cross

Progeny resulting from the mating of males of one breed to females of another breed.

Unilateral Cryptorchid

Male that has retained both testicles.

Weaning

The gradual process where the foal is changed over from mother's milk to solid foods.

Weanling

A foal that has been weaned from its dam.

Withers

The area that is the highest point over the shoulders.

Yearling

A young horse of either gender that is between 12 and 24 months of age.