Biliary Atresia Basic Information Definition In horses, biliary atresia is a rare congenital absence of the common bile duct. Epidemiology Species, Age, Sex Considered a congenital disease; the signalment is…

Back Pain (Thoracolumbar Dysfunction) Basic Information Definition Abnormal function of the thoracolumbar region caused by pain, muscle hypertonicity, or stiffness. Severe cases include neurologic deficits. Synonym(s) • Thoracolumbar hyperesthesia •…

Biliary Obstruction Basic Information Definition Large colon displacement and cholelithiasis are the most common causes of acute biliary obstruction in adult horses. Rarely, foals may develop biliary obstruction secondary to…

Atonic/Hypotonic Bladder Basic Information Definition Dysuria or incontinence caused by sensory and motor deficits of the nervous system Synonym(s) Atonic or paralytic bladder, lower motor neuron bladder, spastic bladder, upper…

Arsenic Toxicosis Basic Information   Definition Arsenic toxicosis is the syndrome caused by exposure to injurious amounts of inorganic arsenic (trivalent arsenic, pentavalent arsenate) or organic arsenic (aliphatic, aromatic, and phenylarsenic…

Ascariasis Basic Information   Definition Mange caused by a variety of mites, including the chorioptic (leg mange) and psoroptic families Synonym(s) Mange Epidemiology Genetics and Breed Predisposition Chorioptic mange typically affects…

Anthrax Basic Information   Definition Anthrax is an infectious disease caused by ingestion of spores of a bacterium that multiplies upon inoculation or ingestion and secretes lethal toxins. A spore is…

Atrioventricular Block, First Degree Basic Information Definition Delayed conduction of the supraventricular impulse at the level of the atrioventricular (AV) node, resulting in a prolonged PQ interval. Synonym(s) First-degree AV…

Anemia, Immune-Mediated Basic Information Definition Anemia resulting from a loss of erythrocytes caused by increased destruction by autoantibodies and complement. Synonym(s) • Autoimmune hemolytic anemia • Immune-mediated hemolytic anemia (IMHA)…

Aflatoxin Toxicosis Basic Information Definition Aflatoxins are hepatotoxic mycotoxins (mold toxins) produced by various Aspergillus spp. and other fungi, most commonly A. flavus and A. parasiticus. Aflatoxin can contaminate a…