Enlarged lymph nodes in dogs and how fine-needle tests help diagnose

Abstract

Lymphadenomegaly is the enlargement of the lymph node/nodes, due to various nonneoplastic or neoplastic processes, observed mainly in dogs, rarely in other animal species. The first step of a diagnostic procedure in cases of lymph nodes enlargement, apart from physical examination and morphological blood analysis, should be a cytological examination of an enlarged lymph node/nodes. The aim of the present study was to determine the character and the cause of the lymph node/nodes enlargement in dogs and to evaluate the usefulness of fine-needle cytology in a diagnosis of lymphadenomegaly. The study was performed on dogs submitted to consultation in the Small Animal Clinic of Department of Clinical Sciences, Warsaw University of Life Sciences, due to generalized or local lymphadenomegaly, and in which fine-needle biopsy was made. A signalement, general state of dog, the presence and duration of clinical signs, the character (generalized vs. localized) and intensity (mild, moderate or severe) of lympadenomegaly were recorded during physical examination. The average age of dogs examined was 8 years, 64 were males and 36 were females of various breeds; however the majority of them were greater than 25 kg in weight. The cytological diagnosis including most often lymphoma and reactive hyperplasia, more seldom metastatic neoplasm and lymphadenitis were recognized, some of the samples were considered nondiagnostic/nondefined. On the basis of the present results it can be concluded that cytological examination of good quality samples allows to obtain final diagnosis in over 90% of lymphadenomegaly. Higher incidence of canine lymphomas in males is suggested.