Clinical and xeroradiographic lymphangiography studies of acute and chronic Brugia pahangi infections in dogs.

Xeroradiographic lymphangiography was carried out at approximately monthly intervals on five dogs during the first 18 weeks following infection with 400 Brugia pahangi infective larvae in the left rear paw. Clinical signs, body temperatures and microfilaria counts were also monitored during this time. Similar observations were made on nine dogs with chronic infections (one to five years duration) of 200 infective larvae in unilateral inguinal sites. Standard thoracic radiography was conducted on all dogs. Surgical occlusion of the major afferent ducts to the popliteal lymph nodes of the infected and noninfected limbs of a chronically infected dog was performed to study oedema induction and resolution. This non-invasive lymphangiographic technique demonstrated marked differences in lymphatic changes among individual dogs. The severity of lymphatic pathology correlated with clinical signs of limb oedema and low microfilaria counts. Chronically infected dogs also demonstrated a variety of pathological manifestations: two dogs presented lymphatic cording and another showed transient lymphadenitis with fever and pulmonary arterial opacities. Surgical occlusion of major lymphatic ducts in an uninfected limb resulted in short-term oedema, while occlusion caused by B. pahangi in acutely infected dogs resulted in more persistent oedema. Surgical occlusion of a major duct in a chronically infected limb did not result in oedema. Xeroradiographic lymphangiography revealed a spectrum of lymphatic pathology in Brugia pahangi-infected dogs and demonstrated the value of this animal model for the study of the pathogenesis of chronic lymphatic filariasis.