Department of Veterinary Science

Department of Veterinary Science > Animal Genetic Testing & Research Laboratory

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Traditional Bloodtyping

Consists of testing blood samples for 7 blood group and 10 biochemical marker systems.  Uses of bloodtyping include: 

• parentage verification
• paternity testing
• identification of individual horses in drug testing cases or cases where horses with similar color and markings may have been switched.

Traditional bloodtyping is used by the majority of breed organizations.  Bloodtyping consists of testing genetic differences for nearly 40 different factors, including red cell antigens and serum proteins.  The sample required consists of two tubes of blood - one collected in anticoagulant, and one serum tube. 

Red Cell Typing
Unlike the relatively simple human ABO system, the horse has 7 systems, each of which contain a number of specific “factors”.   Because of the variety of possible combinations, red cell typing is very informative for parentage determination.  For each “factor” or red cell antigen that we test for, we must develop our own specific “reagent” or antibody to detect that factor.  Our panel of reagents is screened exhaustively for specificity and reliability in our tests.

Biochemical Polymorphisms
Both serum proteins and red cell proteins are tested for variation (polymorphisms) by several gel electrophoretic techniques.  Ten different systems are tested with these methods, and when combined with the results of the red cell laboratory, provide a profile of an individual horse that can be compared to the bloodtypes of its sire and dam.  When there are no discrepancies between the factors possessed by the sire, dam and foal, we say that the “Parentage Qualifies”.

Bloodtyping submission form

list of services

Hemolytic Disease Prevention (Neonatal Isoerythrolysis, NI)

Hemolytic disease of the newborn, also known as neonatal isoerythrolysis (NI), is a serious problem in newborn foals whose red cell type is incompatible with their dams’.  A foal which inherits a red cell factor from its sire that the dam does not possess, is at risk for this condition which results in the destruction of the foal’s red cells after the foal is born and nurses the mare’s colostrum.  There is no in utero effect, since the antibodies against the foal’s red cells cannot cross the placenta.  However, the colostrum is rich in antibodies, and in mares that are sensitized to a red cell factor, the colostrum can be deadly instead of protective.  The Bloodtyping lab offers a serum screening service for mares with a history of NI.  A serum sample is submitted within 30 days prior to the mare’s due date.  If antibody levels to one of several “high risk” factors are elevated, it is essential to prevent the foal from nursing its dam's colostrum, and provide it with a substitute colostrum.  In addition, mares with a known history of NI can be crossmatched to a stallion that does not have the red cell factor to which the mare has become sensitized. That way, the foal cannot inherit the factor from the sire, and will not be susceptible to the mare’s antibodies.

Our NI testing program can prevent this problem by:  

• crossmatching stallion and mare bloodtypes or
• testing serum from the mare 30 or less days before foaling

NI Testing submission form

list of services

DNA Testing

DNA testing is available to generate DNA types and perform parentage testing. We use a panel of 13 microsatellite markers for standard testing. DNA can be extracted from hair, blood or any tissue. DNA types and Bloodtypes are NOT interchangeable. We cannot perform a parentage analysis on a foal that has been DNA typed but whose parents have been bloodtyped. However, DNA types can be generated from stored serum samples of horses that were previously bloodtyped.

DNA Testing submission form

list of services

Color Testing

Prediction of color can be important to breeders.  We offer 7 tests: Tobiano, E Locus (red gene), Cream gene, Agouti, Sabino, Silver Dapple (Z), Champagne.

Tobiano
The lab offers testing to determine homozygosity for the Tobiano (spotted) gene. Since the tobiano color pattern is valued and is dominant, horses that possess two copies of the gene (homozygous) are of special value to breeders, as ALL their offspring will inherit the tobiano color pattern. We no longer perform the serum protein test based on bloodtypes due to its low reliability.  Instead, the University of Kentucky Animal Genetic Testing Lab is proud to offer the most reliable test for the Tobiano spotting pattern yet developed.  Dr. Samantha Brooks of the University of Kentucky discovered an inversion on chromosome 3 that appears to be 100% concordant with the presence of the tobiano pattern.  This test replaces the former double marker test previously offered.  Please be advised that Tobiano testing reports will reflect this change.

E locus (red gene)
The Extension locus is another gene related to color, and determines whether a horse has black “points” as in the bay coat color pattern (the mane, tail, legs and tips of the ears are black).  The allele responsible for this pattern is designated as E, the capital letter indicating it is dominant.  The alternative allele, e, is recessive, and when a horse has two copies of this allele, as in ee, the horse lacks black pigment in the extremities, as in chestnut horses.  For owners of a bay or black horse that want to know if that horse is homozygous for the Extension locus, and thus will always have offspring with black points, a DNA-based test is available.

Cream (Dilution) Gene
The cream gene, designated Cr, is a dominant dilution gene that causes a reduction in red pigment in the body hair and mane and tail hair. It acts on any base color- therefore a sorrel horse that inherits one copy of the Cr allele is palomino (ee, Cr/cr), a sorrel that inherits a Cr from each parent is Cr/Cr and is a cremello (ee, Cr/Cr). A bay horse that inherits a Cr allele from one parent is a buckskin (E/-, Cr/cr), while one that is homozygous for Cr is a perlino (ee, Cr/Cr). True black horses can mask the presence of the Cr gene, so it is possible for a black horse to produce palominos or buckskins. Cream is a different gene than Dun, which is also a dilution gene. In general, dun horses have a dorsal stripe. WHY TEST- Owners of a black horse with a palomino or buckskin parent may want to determine if the horse carries an unexpressed Cr allele. Horses carrying the champagne gene may be confused with horses carrying the Cr gene-this test will verify if the horses indeed possess the Cr allele. It will also determine if a dun or gray horse may also possess a Cr allele.

Agouti Gene
The A locus can be thought of as the gene that determines if a horse is bay or black, although other genes come into play. A horse that has at least one dominant "A" allele will be bay if it also possesses at least one "E" allele. A horse that is homozygous recessive for "a", that is "aa", will be black if it also possesses a "E" allele. All black horses are "EE or Ee and aa". WHY TEST- If a horse is homozygous for "e", it will have a sorrel or chestnut base coat regardless of what genes it carries at the A locus. Thus a chestnut horse may be able to produce blacks if it carries an "a" allele and is bred to another horse carrying the "a" allele and a "E". If a person has a black horse and wants to know if a breeding to a chestnut horse will produce a black, the black horse needs to tested for the E locus and the chestnut horse needs to be tested for the A locus. A black horse that tests homozygous for "a" must also be homozygous for "E" to produce 100% blacks/bays/buckskins.

Sabino
Sabino is a Paint color pattern that is variably expressed and can range from white stockings and a blaze to white leg and face markings and extensive white spreading up from the belly into the body area. The mutation we detect is indicative of the Sabino1 gene. Homozygous sabinos may have more extensive white than heterozygous horses. There is more than one sabino gene so that a horse that appears to have the sabino pattern may test negative for the Sabino1 gene. So far all horses that test positive for Sabino1 have the sabino pattern.

Silver Dapple (Z)

The Silver Dapple mutation results in a chocolate colored horse that has a lighter mane and tail.  It is most commonly found in pony breeds and gaited horse breeds such as the Rocky Mountain Horse.  The mutation requires the presence of at least one E allele to be expressed.  Therefore genetically black or bay horses alone express it if they carry one or two Z alleles.  A chestnut horse (ee) may carry a Z allele, but there is no effect on color. It is thought that horses homozygous for the Z allele have a whiter mane and tail than the heterozygotes.

Champagne

We now offer the test for the mutation responsible for the Champagne factor in horses.  The mutation was discovered here at the University of Kentucky.  The Champagne gene is a dilution gene often confused with the Cream dilution gene.  Unlike horses carrying a single Cream gene, Champagne horses have pink skin which becomes mottled in exposed areas such as the muzzle.  Also Champagne foals are born with blue eyes that later darken to hazel or brown.  A true black horse can mask the presence of the Cream gene, but a black horse carrying the Champagne gene is generally a chocolate color.  There is no added effect if a horse carries two copies of the Champagne gene, whereas the homozygotes for the Cream gene create a more dilute horse with pink skin (cremellos and perlinos).  Therefore the ability to test for the Champagne gene can distinguish homozygotes from heterozygotes, as well as more clearly determine the genotype of dilute pigmented horses.

Color Testing submission form

Guide to Color Gene Testing

list of services

Disease Mutation Testing

We offer 2 tests: Junctional Epidermolysis Bullosa (JEB) and Overo Lethal White Syndrome (OLWS).

Junctional Epidermolysis Bullosa (JEB)

JEB is a condition found in American Saddlebreds and certain other light breeds of horses. It results in a lethal skin condition in affected foals.  The foals must inherit the mutation from both parents.  A test to identify carriers is now available. The mutation was discovered at the University of Kentucky Animal Genetic Testing Lab with support from the American Saddlebred Horse Association.  The mutation for the Saddlebred form of JEB is different than that for the Belgian Horse JEB.  We offer only the Saddlebred JEB test.  Carriers can be safely bred as long as they are not bred to another carrier.  Cost: $50 from blood or hair samples.

JEB affected foal.
Photo courtesy of the American Saddlebred Horse Association.

Overo Lethal White Syndrome (OLWS)

This is so named because affected foals are all white or near white at birth and have improperly formed rectal tissue resulting in death or requiring euthanasia at a few days of age.  It is caused by a mutation that in the heterozygous form results in a frame overo pattern.  Therefore the color pattern is very desirable for Paint or Pinto horse breeders.  There are no health effects for carriers.  However if two carriers are bred 25% of the foals on average will be homozygous for the mutation and will be affected.  Although most common in Paint horses and Quarter horses, the mutation has been found in Tennessee Walking Horses as well.

Disease Mutation testing submission form

Research

The research lab also has an active research program dedicated to genetic research of the horse.  Revenues generated by service contracts help fund: 

• important research on genetic diversity of rare breeds
• development of a genetic map of the horse
• identification of genetic markers for heritable problems in the horse

Canine DNA genotyping and parentage testing is available using the new ISAG (International Society for Animal Genetics) panel of microsatellite markers. Samples may be submitted as blood or cheek swabs.  Testing is for $40 per dog.  Discounts are available for litter typing and additional sire testing.  Please contact Dr. Graves at 859-257-2510 or ktgraves@uky.edu.

Contact us

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The lab is located in the Dimock Animal Pathology Building. 

Directions from I-75:

• Take Exit 115 toward Lexington (South) on Newtown Pike (922).
• Go to Main Street and turn left (cemetary monument businesses are on each corner and Salvation Army across street on left).
• Stay in right hand lane and turn right onto Broadway.
• Stay on Broadway to a large intersection (St Joe’s Hospital across street on left) and turn left onto Waller Avenue. 
• Stay on Waller across railroad tracks to second light which is Nicholasville Road.
• Go straight to NEXT light (Commonwealth stadium will be on the far right corner)and turn left onto University Drive, a split 4-lane road.
• Take the second left (turn lane) onto a short road at the end of which is a Stop sign and the Veterans Hospital. 
• Turn right onto VA Road.  Go past the Veterans Hospital, then past the Peter Bosomworth Bldg and then the very next building on the left is the Animal Pathology Building.  There is no sign.  There are 4 meter parking spots behind the building.