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For horse specific karyotyping information, please see Horse Karyotyping.
Mammalian genes are found in cell nuclei on linear structures called chromosomes. Every species has a characteristic number and array of chromosomes which are necessary for the precise control of development, metabolic function and reproduction. Included in the array of chromosomes are those which determine sex; the female contributes a chromosome called X and the male either an X or a Y.
Occasionally, chromosomal material is lost or rearranged during the formation of gametes or during cell division of the early embryo. Usually such changes are so detrimental to normal development and the maintenance of life that either the resulting gametes fail to form a zygote or growth stops in early embryonic stages and the pregnancy is terminated by miscarriage or resorption. Rarely, if the chromosomal rearrangement or loss is relatively minor, the resulting embryo completes development, but subsequently may have abnormal patterns of growth, maturation and reproduction.
Karyotyping test is recommended for animals that present reproductive problems (infertility or subfertility), ambiguous external genitalia or poor development and growth. Detection of chromosomal abnormalities can save breeders time and money by identifying animals that are poor performance and breeding risks.
Blood Sample (Sodium Heparin green top tubes)
Karyotyping can be performed from peripheral blood lymphocytes isolated from a whole blood sample (Sodium Heparin green top tube) which has been sent to the laboratory by overnight courier. Lymphocytes are cultured for several days under conditions that stimulate them to divide and then harvested. Nuclei of cells are treated to expose chromosomes which are then stained and photographed. Chromosomes are examined for number and structure. The procedure typically takes from 3-5 weeks to complete.
Skin biopsies are also a source of cells for karyotyping tests. Arrangements need to be made with the laboratory for submission of samples other than blood.