Pyelonephritis

From Dog
Pyelonephritis in a dog resulting in retroperitoneal abscess and regional cellulitis, causing ventral displacement of the descending colon[1]

Pyelonephritis is an inflammatory response of the kidney due to bacterial infections and frequently results in acute or chronic renal disease.

If the conditions continues, pyonephrosis may occur, characterized by elevated pressure (similar to hydronephrosis) and suppurative destruction of the parenchyma of the kidney with complete or nearly complete loss of renal function[2].

The majority of cases are infections limited to the renal pelvis and caused by ascending infections from the bladder due to cystitis.

Secondary causes of pyelonephritis include congenital diseases such as:

Infectious agents implicated in the development of pyelo­nephritis include:

- Escherichia coli[8]
- Staphylococcus hyicus
- Streptococcus β-haemolyticus
- Enterococcus spp
- Proteus spp
- Klebsiella spp
- Leptospira spp
- Pasteurella spp
- Pseudomonas spp
- Corynebacterium spp
- Salmonella spp[9]
- Mycoplasma spp
- Cryptococcus spp[10]

Pyelonephritis may be unilateral (ascending UTI) or bilateral (ascending UTI, hematogenous infection).

Clinical signs of pyelonephritis are varied or may be absent altogether, making diagnosis a challenge.

Anorexia, fever, renal pain and haematuria may be ascertained from clinical and laboratory examination but some dogs are asymptomatic and only diagnosed after chronic renal disease has established, with signs of uremia, hyperkalemia and polyuria/polydipsia.

Ultrasound imaging may reveal renomegaly and renal pelvic dilatation[11].

Polycythemia has been reported as a rare side-effect associated with necrotizing pyelonephritis in the dog, presumably due to increased erythropoietin levels[12].

Urine culture may return a positive bacterial growth but whether this is renal or urinary bladder origin is debatable.

A differential diagnosis would include renal lymphoma and hyperadrenocorticism.

Treatment is based on culture and sensitivity testing of urine and response to therapy. Cephalosporins or amoxycillin/clavulanate are first drugs of choice.

in cases of severe infections with secondary pyonephrosis, percutaneous ultrasound-guided drainage of the renal pelvis and flushing with povidone iodine solutionmay be required.

References

  1. Hylands R (2006) Veterinary diagnostic imaging. Retroperitoneal abscess and regional cellulitis secondary to a pyelonephritis within the left kidney. Can Vet J 47(10):1033-1035
  2. Szatmári V et al (2001) Ultrasound-guided percutaneous drainage for treatment of pyonephrosis in two dogs. J Am Vet Med Assoc 218(11):1796-1799
  3. Crawford JT & Adams WM (2002) Influence of vestibulovaginal stenosis, pelvic bladder, and recessed vulva on response to treatment for clinical signs of lower urinary tract disease in dogs: 38 cases (1990-1999). J Am Vet Med Assoc 221(7):995-999
  4. Abraham LA et al (2003) Renal dysplasia and urinary tract infection in a Bull Mastiff puppy. Aust Vet J 81(6):336-339
  5. Patel VR et al (2006) Comparison between ureteral replacements using a transverse tubularized colonic tube or ileal ureter: experimental study in dogs. J Pediatr Surg 41(4):799-803
  6. Pozzi A et al (2006) Colonic seromuscular augmentation cystoplasty following subtotal cystectomy for treatment of bladder necrosis caused by bladder torsion in a dog. J Am Vet Med Assoc 229(2):235-239
  7. Jamieson PM & Chandler ML (2001) Transient renal tubulopathy in a Labrador retriever. J Small Anim Pract 42(11):546-549
  8. Yuri K et al (2000) Pathogenicity of Escherichia coli from dogs with UTI in relation to urovirulence factors. J Vet Med Sci 62(11):1197-1200
  9. Crow SE et al (1976) Pyonephrosis associated with Salmonella infection in a dog. J Am Vet Med Assoc 169(12):1324-1326
  10. Newman SJ et al (2003) Cryptococcal pyelonephritis in a dog. J Am Vet Med Assoc 222(2):180-183
  11. D'Anjou MA et al (2011) Clinical significance of renal pelvic dilatation on ultrasound in dogs and cats. Vet Radiol Ultrasound 52(1):88-94
  12. Kessler M (2008) Secondary polycythaemia associated with high plasma erythropoietin concentrations in a dog with a necrotising pyelonephritis. J Small Anim Pract 49(7):363-366