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Incubation Period: Disease Timeline in Horses
Incubation is the interval between a horse’s initial exposure to an infectious agent and the appearance of the first recognizable clinical signs of disease. During this period the pathogen is replicating within the host but has not yet produced symptoms detectable by the handler or veterinarian, which is why horses in the incubation phase can…
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Lysis
Lysis is the destruction or breakdown of a cell caused by damage to its outer membrane, releasing the cell’s contents into the surrounding tissue or fluid. In equine medicine the term appears most often as a suffix identifying which cells are being destroyed, and the distinction matters because the clinical picture changes with the cell…
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Roan Horse: Coat Color, Genetics, and Variants
A roan horse has a base coat color mixed with white hairs distributed evenly across the body from birth, while the head, mane, tail, and lower legs retain the base color at full intensity. The white interspersion is not progressive; a roan horse does not lighten with age the way a grey does. The white…
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Horse Coat Color Genetics: Base Colors, Dilutions, Patterns
Every coat color a horse carries is the product of two pigments and a small number of genes that control where and how much of each pigment is made. The system is layered: base color is set first, dilution alleles lighten it, and pattern genes redistribute or suppress it. Understanding how each layer works makes…
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Aging a Horse by Its Teeth: Eruption and Galvayne’s Groove
Examining a horse’s teeth to estimate its age is one of the oldest diagnostic skills in equine practice. It works because horses’ teeth erupt on a predictable schedule, wear at a predictable rate, and change shape and angle in ways that correspond to age. The estimate is useful and often close, but it is not…
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How to Measure a Horse in Hands: Height and Withers Guide
Horse height is expressed in hands. One hand equals four inches. The system originates from the breadth of an adult human hand, standardized by Henry VIII in 1541, and it has not changed since. A horse measured at 15.2 hands stands 15 hands and 2 inches — 62 inches, or 5 feet 2 inches at…
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Horse Gestation: Length, Stages, and Foaling
Mare gestation averages 340 days, with a normal range of 320 to 370 days. Breed, season of conception, and individual variation all influence length; draft mares tend to carry slightly longer than light breeds. Gestation is divided into three trimesters. The first (days 1-114) covers embryonic implantation and early organogenesis. The second (days 115-226) is…
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Papule
A papule is a small, solid, raised elevation of the skin, typically less than one centimeter in diameter, with no visible fluid content. The elevation is produced by localized cellular proliferation, edema within the dermis, or infiltration of inflammatory cells. It is one of the primary lesion types used to classify skin abnormalities in equine…
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Melanin
Melanin is the pigment responsible for every color seen in a horse coat, mane, tail, skin, and eyes. All coat color in horses traces to a single pigment-producing cell type, the melanocyte, which manufactures melanin and deposits it into the growing hair shaft. Two chemically distinct forms exist. Eumelanin produces black and brown pigment. Phaeomelanin…
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Pruritus in Horses: Causes of Equine Itching
Pruritus is the sensation of itch that compels a horse to rub, bite, scratch, or roll against fixed objects. It is not a disease but a clinical sign of an underlying process that irritates cutaneous nerve endings in the skin and triggers the scratch reflex. In horses the most frequent cause is insect hypersensitivity, particularly…