An unusual case of spontaneous kidney rupture secondary to nematode larvae diagnosed with contrast-enhanced ultrasonography in a dog

AIM OF THE STUDY : To describe the utility of contrast-enhanced ultrasonography (CEUS) for revealing early evidence of an ongoing hemorrhage in a dog with spontaneous kidney rupture and the unusual presence of nematode larvae within the renal parenchyma. MATERIAL & METHODS : A 9 month old male Boxer dog was examined because of acute onset of hypovolemic shock. There was no known trauma. Venous blood for complete blood count, chemistry tests and coagulation profile was obtained. Subsequently, abdominal ultrasound, analysis of the peritoneal fluid and CEUS were scheduled, followed by laparotomy with nephrectomy of the right kidney. Histological examination and PCR for 18S gene were performed, along with urinalysis and serial fecal tests. After surgery, the dog had been examined regularly up to 1 year. RESULTS : Physical examination revealed pale mucous membranes, tachycardia with weak peripheral pulse, generalized weakness, abdominal distension and pain on palpation. Laboratory findings were consistent with hemorrhage. Abdominal ultrasonography revealed free fluid and a mass in the cranioventral pole of the right kidney. Fluid removal by abdominocentesis was consistent with free blood. The early arterial phase of CEUS study was characterized by a small area in the renal cortex without enhancement and by multiple septa with strong enhancement extending from the renal cortex into the center of the mass. In the late corticomedullary phase, kidney enhancement was homogeneous without filling defects. Laparotomy confirmed the ruptured kidney. The postoperative course was uncomplicated. A histological diagnosis of severe, interstitial hemorrhage, mesangiosclerosis with endocapillary hypercellularity, and mild multifocal interstitial granulomatous nephritis associated with nematode larvae was posed. PCR resulted negative. No parasite ova in the urine or feces nor clinicopathological abnormalities were detected at follow-up examinations. CONCLUSIONS : The CEUS findings of this dog were compatible with an acute hematoma or hemangiosarcoma (1). An abscess, although possible, was ruled out because of hyperechoic septa which, instead, were suggestive of an active hemorrhage (2). With regard to nematode larvae, Angiostrongylus vasorum was considered a possibility based on the histological lesions and literature (3). Furthermore, asymptomatic cases, acute bleeding and false negative fecal tests have been recorded (3), as in this case. However, because PCR results were negative, a definitive diagnosis could not be confirmed and remains speculative at best. BIBLIOGRAPHY : 1. Haers H et al Contrast harmonic ultrasonographic appearance of focal space-occupying renal lesions. Vet Radiol Ultrasound 2010; 51:516-522 2. Poletti PA et al Blunt abdominal trauma: does the use of a second-generation sonographic contrast agent help to detect solid organ injuries? Am J Roentgenol 2004; 183:1293-1301 3. Denk D et al Disseminated angiostrongylosis with fatal cerebral hemorrhages in two dogs in Germany: a clinical case study. Vet Parasitol 2009; 160: 100-108