Glomerular filtration rate determination by computed tomography in two pet rabbits with renal disease

Abstract

CASE DESCRIPTION A 3-year-old and a 7-year-old spayed female rabbit (Oryctolagus cuniculus) were evaluated because of digestive stasis associated with renal asymmetry. CLINICAL FINDINGS Neoplasia of the right kidney was diagnosed via cytologic analysis in the 3-year-old rabbit. Ureterolithiasis of the left kidney was diagnosed via abdominal ultrasonography in the 7-year-old rabbit. To evaluate whether unilateral nephrectomy was indicated, evaluation of glomerular filtration rate by dynamic CT (CT-GFR) was performed on both rabbits. On the basis of the functional and morphological CT-GFR results, radical nephrectomy was recommended for the rabbit with renal neoplasia whereas a more conservative approach was recommended for the other rabbit. TREATMENT AND OUTCOME The rabbit with renal neoplasia underwent radical nephrectomy without complication. The rabbit with ureterolithiasis underwent ureteral stent placement, and the renal pelvic dilatation resolved. Both rabbits maintained unremarkable serum urea and creatinine concentrations after surgery. CLINICAL RELEVANCE GFR is a highly useful and reliable variable for the evaluation of renal function but is difficult to assess with routine clinical laboratory tests. The CT-GFR technique described here was quickly performed, was technically suitable for rabbits, and provided clinically relevant information. Studies are required to establish reference values for CT-GFR in rabbits.

Description of digital fluoroscopic excretory urography in healthy New Zealand rabbits (Oryctolagus cuniculus)

“…For example, if a nephrostomy or nephrectomy is necessary, the DFEU may provide some qualitative information about the function and patency of the contralateral kidney and ureter. However, renal scintigraphy 23 or CTEU, 4 which are described in rabbits, allow for assessment of renal function as well as evaluation of the GFR in each kidney and are preferred over DFEU due to the more subjectivity of this test. Another technique described in rabbits for the assessment of GFR is the clearance of gadolinium‐based contrast medium monitored via MRI, but this technique has disadvantages such as being more expensive and requiring prolonged anaesthesia 24 25 …”

“…3 More than 70 per cent of geriatric rabbits present renal lesions at necropsy. 4 This high prevalence may be related to conditions such as infectious nephritis caused by Encephalitozoon cuniculi 5 or nephrolithiasis secondary to metabolic imbalances, such as those resulting from a high dietary calcium intake or insuicient water provision. 6 Congenital defects, primary or metastatic renal neoplasia, and other conditions such as pyelonephritis and amyloidosis are identiied less commonly.…”

“…6 Congenital defects, primary or metastatic renal neoplasia, and other conditions such as pyelonephritis and amyloidosis are identiied less commonly. 4 Evaluation of the renal function using ancillary routinely tests may be of limited value for rabbits. Glucosuria and proteinuria can be a normal inding ater physical exercise or stress; the high susceptibility of rabbits to stress can, therefore, hide urinary changes associated with earlier stages of kidney dysfunction.…”

Placement of ureteral stents in three rabbits for the treatment of obstructive ureterolithiasis

“…In Case 1, glomerular filtration rate evaluated by dynamic CT scan (CT‐GFR) was considered reduced in both kidneys (Glomerular filtration rate (GFR) in the right kidney: 1.02 mL/min/kg; GFR in the left kidney: 0.62 mL/min/kg), compatible with subclinical renal insufficiency (feline reference values: 2.5 mL/min/kg) (Zoller et al . 2017).…”