What Is Your Diagnosis?

Danielle M. Babski Veterinary Teaching Hospital, College of Veterinary Medicine, University of Georgia, Athens, GA 30602.

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Sonia Crochik Veterinary Teaching Hospital, College of Veterinary Medicine, University of Georgia, Athens, GA 30602.

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Benjamin M. Brainard Veterinary Teaching Hospital, College of Veterinary Medicine, University of Georgia, Athens, GA 30602.

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 VMD, DACVA, DACVECC

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History and Physical Examination

A 3-year-old neutered male Labrador Retriever was referred for evaluation because of vomiting, lethargy, and inappetence of approximately 3 days' duration. In the 24 hours prior to referral, 2 L of isotonic crystalloid fluids had been administered IV; during this period, the dog was anuric. Abdominal radiography had been performed by the referring veterinarian prior to fluid administration and revealed a minimally distended urinary bladder and no major abnormalities. The referring veterinarian also performed a CBC and serum biochemical analysis; urine specific gravity was also measured. Normochromic, normocytic anemia (Hct, 30.9%; reference range, 36% to 60%) was detected. Abnormalities on serum biochemical analysis included high concentrations of SUN (139 mg/dL; reference range, 6 to 25 mg/dL), creatinine (12.3 mg/dL; reference range, 0.5 to 1.6 mg/dL), and phosphorus (14.3 mg/dL; reference range, 2.5 to 6.0 mg/dL) and mild hypochloremia (97 mEq/L; reference range, 102 to 120 mEq/L). Urine specific gravity determined via refractometry was 1.007 g/mL. Besides IV fluid therapy, the dog was treated with enrofloxacin, cimetidine, maropitant citrate, and sucralfate prior to referral for treatment of suspected anuric renal failure. The owners expressed concern about the possibility of the dog having been poisoned. There was no history of trauma, although the dog wandered freely on a large area of land.

On physical examination, the dog had signs of depression and had a normal heart rate of 100 beats/min, a rectal temperature of 37.7°C (99.9°F), and a respiratory rate within the reference range. No abnormalities were found on thoracic auscultation. The dog had chemosis and subcutaneous edema on the ventral aspect of its neck. The abdomen was soft; palpation did not elicit signs of pain, but it appeared distended. The urinary bladder was not palpable. Serum creatinine concentration was high (14.5 mg/dL; reference range, 0.5 to 1.5 mg/dL) and had not decreased despite fluid therapy. Abdominal radiographs were obtained (Figure 1).

Figure 1—
Figure 1—

Right lateral (A) and ventrodorsal (B) radiographic views of the abdomen of a 3-year-old neutered male dog with azotemia and a history of vomiting, lethargy, and inappetence of approximately 3 days' duration. Images were obtained after the dog received IV fluid therapy.

Citation: Journal of the American Veterinary Medical Association 240, 12; 10.2460/javma.240.12.1415

Determine whether additional imaging studies are required, or make your diagnosis from Figure 1—then turn the page

Diagnostic Imaging Findings and Interpretation

A diffuse soft tissue opacity is evident throughout the abdomen with loss of detail in the retroperitoneal space causing the kidneys to be partially obscured and ventrally displaced along with the intestines (Figure 2). These findings are consistent with a moderate to severe volume of retroperitoneal effusion. Mild loss of serosal margin detail is also present in the peritoneal cavity, suggesting mild peritoneal effusion; the urinary bladder is minimally distended.

Figure 2—
Figure 2—

Right lateral radiographic views of the abdomen of the same dog as in Figure 1. A—Same radiographic image as in Figure 1; notice the distended abdomen and the loss of serosal detail in the retroperitoneal space (wavy arrows). B—Right lateral radiographic image that had been obtained by the referring veterinarian 24 hours prior to referral and before IV fluid therapy; notice that there is no evidence of retroperitoneal effusion.

Citation: Journal of the American Veterinary Medical Association 240, 12; 10.2460/javma.240.12.1415

Because laboratory results and lack of urine production suggested acute renal failure and the kidneys were radiographically obscured by retroperitoneal effusion, ultrasonography was indicated to further evaluate the kidneys. Ultrasonographically, both kidneys were severely hyperechoic with a medullary rim sign (medullary echogenic line parallel to the corticomedullary junction; Figure 3). Although not pathognomonic, the renal changes are most compatible with ethylene glycol intoxication. Similar to the radiographic findings, ultrasonography revealed that the urinary bladder was minimally distended and fluid (anechoic signal) was identified surrounding both kidneys, within the retroperitoneal space, and in the peritoneal cavity. These findings are compatible with severe bilateral perirenal effusion and mild peritoneal effusion.

Figure 3—
Figure 3—

Sagittal ultrasonographic image of the left kidney (A) and transverse ultrasonographic image of the caudal pole of the left kidney (B). A—Notice the hyperechoic renal cortex and the medullary rim sign (arrow). B—Notice the perirenal fluid (wavy arrow).

Citation: Journal of the American Veterinary Medical Association 240, 12; 10.2460/javma.240.12.1415

Comments

A presumptive diagnosis of ethylene glycol intoxication was made on the basis of laboratory and diagnostic imaging findings. Urine analysis results, reported after the diagnostic imaging, revealed many calcium oxalate monohydrate crystals, and this, combined with the ultrasonographic findings, supported the diagnosis of ethylene glycol intoxication.

Abdominal radiography performed by the referring veterinarian 24 hours prior to initial evaluation and before IV fluid therapy revealed no evidence of retroperitoneal effusion (Figure 2). We speculate that the IV administration of a large amount of fluid in the presence of acute renal failure and, more specifically, anuria contributed to the extravasation and accumulation of fluid within the retroperitoneal space and to a lesser degree in the peritoneal spaces. Patients with large effusions, also termed perirenal retroperitoneal effusions to denote their extent, may have evidence of fluid accumulation surrounding the caudal pole of the kidney that may extend beneath the hypaxial muscles caudally, outlining retroperitoneal fat.1

Renal ultrasonographic findings in dogs with ethylene glycol intoxication include hyperechoic renal cortex, medullary rim sign, and perirenal effusion, although these findings are not considered pathognomonic.1–5 Deposition of calcium oxalate crystals is believed to account for the changes observed in the kidneys.2,3

The mechanism by which fluid accumulates in the perirenal retroperitoneal space in acute renal failure is uncertain. Perirenal fluid has been described in dogs with acute renal failure, including dogs with ethylene glycol intoxication.1 Other reported causes of perirenal fluid in dogs include urine leakage, hemorrhage, abscess formation, perirenal pseudocysts, and neoplasia.1

Delays in diagnosis and treatment of dogs with ethylene glycol intoxication are associated with a high mortality rate. Prognosis is dependent on the time from ingestion until treatment is initiated; generally, dogs treated within 8 hours after ingestion have a good prognosis.6 Treatment was not pursued in this case described in the present report, and the dog was euthanized.

  • 1. Holloway A, O'Brien R. Perirenal effusion in dogs and cats with acute renal failure. Vet Radiol Ultrasound 2007; 48:574579.

  • 2. Adams WH, Toal RL, Walker MA, et al. Early renal ultrasonographic findings in dogs with experimentally induced ethylene glycol nephrosis. Am J Vet Res 1989; 50:13701376.

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  • 3. Adams WH, Toal RL, Breider MA. Ultrasonographic findings in dogs and cats with oxalate nephrosis attributed to ethylene glycol intoxication: 15 cases (1984–1988). J Am Vet Med Assoc 1991; 199:492496.

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  • 4. Biller DS, Bradley GA, Partington BP. Renal medullary rim sign: ultrasonographic evidence of renal disease. Vet Radiol Ultrasound 1992; 33:286290.

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  • 5. Mantis P, Lamb CR. Most dogs with medullary rim sign on ultrasonography have no demonstrable renal dysfunction. Vet Radiol Ultrasound 2000; 41:164166.

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  • 6. Rollings C. Ethylene glycol. In: Silverstein DC, Hopper K, eds. Small animal critical care medicine. St Louis: Saunders, 2009;330334.

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