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Dog, mixed breed, female, 2.5 months
Diagnosis: Dog, septal cusp of the tricuspidal valve, haemocyst
Comments: Haemocysts on the atrioventricular valves are common lesions in calves, but occur rarely in other species. They are lined by epithelium and arise from clefts normally present in the substance of the valves in intrauterine life. They can reach 1 cm in diameter and involute during the first months of life. A similar process is known in Beagles and termed valvular telangiectasis.
Photo and author: Alexander Weiss, Department of Veterinary Pathology, Freie Universität Berlin, Germany