Case Study

Pyelonephritis and a left renolith in a 10 year old FS DSH cat

A 10-year-old FS DSH was presented for vomiting, lethargy, and anorexia. On physical examination, the patient was bright, alert and responsive, but had evidence of weight loss and dehydration. Also, the cat’s mucus membranes were pale pink, and there was a possible fluid wave in the abdomen. Urinalysis showed alkaline urine with normal specific gravity, 3+ proteinuria, 3+ hematuria, and leukocyturia. Urine culture yielded no growth. CBC was within normal limits. Blood chemistry showed azotemia, hypophosphatemia, and mild hyperglycemia.

DX

Left renolith, acute-on-chronic pyelonephritis suspected

Sonographic Differential Diagnosis

Probable acute on chronic pyelonephritis with calculi. Possible emerging renal lymphoma.

Image Interpretation

The kidneys revealed significantly irregular contour with cortical infarctions and perinephric fat inflammation. A calculus was present in the medulla of the left kidney. Mixed echogenic changes were noted in the renal cortices with some ill defined corticomedullary and pelvic definition. This is most consistent with acute on chronic pyelonephritis with the possibility of emerging lymphoma.

Outcome

A guarded prognosis was given. Renal diet was added to the treatment regimen. On follow up assessment 2 weeks later, the patient was doing well, had an excellent BCS but there had only been a minimal improvement in the azotemia. Antibiotics and Azodyl were added to the treatment plan. A month later, physical examination remained unchanged, but the azotemia and hyperphosphatemia had worsened and thrombocytopenia had developed. Urine was clear, yellow and exhibited low-normal specific gravity (1.015) and a trace of proteinuria. Urine culture yielded no growth. Patient was treated with I.V. fluids, gastroprotectants, antibiotics, and appetite stimulants. However, due to lack of improvement and poor prognosis, the cat was euthanized.

Clinical Differential Diagnosis

Ascites – transudate, modified transudate, exudate. Azotemia – pre-renal (dehydration), renal (primary glomerular disease, chronic renal failure, pyelonephritis, neoplasia), post-renal (ureterolith, obstructive neoplasia). Hematuria – sterile cystitis, neoplasia.

Sampling

Fine needle aspirates were performed of the left kidney cortex and submitted for cytology review to rule out lymphoma and evaluate for the presence of acute-on-chronic inflammatory disease. US-guided FNA from the kidney revealed mild nephritis.