Life-threatening Anemia in a Dog Caused by the Nile Leech, Limnatis nilotica (Hirudinidae) in Israel

This is the second report of a naturally occurring internal hirudiniasis due to the Nile leech (Limnatis nilotica) in a dog in Israel. A 3.5-year-old Shih Tzu dog presented with lethargy, collapse, and severe, life-threatening hemorrhagic anemia. Upon initial physical examinations, at both the referring clinic and the hospital, a sublingual hematoma was erroneously diagnosed a sublingual hematoma. Nevertheless, comprehensive oral examination under general anesthesia revealed no evidence of hematoma, while only two engorged leeches attached to the sublingual mucosa, which were removed. Hemostatic tests showed several and significant abnormalities, previously unreported in similar cases, including prolonged clotting times, hyperfibrinolysis, indicated by increased D-dimer concentration, and decreased antithrombin activity, likely reflecting the systemic impact of the anticoagulants and other bioactive molecules found in leech saliva, which can disrupt the host’s coagulation pathways beyond localized bleeding. The dog was administered a blood transfusion and supportive care, leading to full clinical recovery within three days. The final diagnosis was severe acute hemorrhagic anemia and hypoproteinemia caused by the leech infestation. This report underscores the critical importance of including leech infestation among the differential diagnoses for unexplained acute anemia in dogs, particularly in endemic areas with potential exposure to leech-contaminated water sources. It highlights that leeches might be easily misidentified as hematomas during routine physical examinations, warranting thorough oral and pharyngeal examinations, ideally under sedation or anesthesia, to ensure accurate diagnosis and timely intervention. The unique hemostatic abnormalities observed herein also warrant further investigation into the systemic hemostatic effects of leech saliva.