Bovine Cystitis and Pyelonephritis

Bovine cystitis and pyelonephritis are inflammatory conditions of the urinary bladder and kidneys in cattle, primarily resulting from ascending bacterial infections.

Etiology and Pathogenesis

Historically, the Corynebacterium renale group—including C. renale, C. pilosum, and C. cystitidis—were the predominant pathogens causing these conditions. Currently, other bacteria such as Escherichia coli, Staphylococcus spp., Proteus spp., Streptococcus spp., and Trueperella pyogenes are more frequently isolated from affected cows. These organisms are ubiquitous in the environment and commonly inhabit the vagina and prepuce.

Infections typically ascend from the bladder to the ureters and kidneys, especially when the ureteral mucosa's defense mechanisms are compromised. Factors contributing to this compromise include traumatic events like parturition, vaginal deformities, peak lactation stress, and high-protein diets that elevate urine pH, facilitating bacterial colonization. Additionally, the use of nonsterile catheters can transmit Corynebacterium spp. between cows. Merck Veterinary Manual

Clinical Findings and Lesions

Initial signs may include hematuria in an otherwise healthy cow. As the infection ascends, symptoms can progress to frequent urination attempts, anorexia, mild fever, decreased milk production, colic, restlessness, tail switching, polyuria, hematuria, and pyuria. Chronic cases might present with colic, diarrhea, polyuria, polydipsia, stranguria, and anemia. Pathological findings often reveal a thickened and inflamed bladder, dilated ureters filled with purulent exudate, and kidneys exhibiting multiple small abscesses extending into the cortex and medulla. Merck Veterinary Manual

Clinical Laboratory Findings

Laboratory tests play a pivotal role in diagnosing bovine cystitis and pyelonephritis. Key findings include:

• Urinalysis:

  • Presence of white blood cells (pyuria) and bacteria (bacteriuria) in the urine sediment.

  • Positive dipstick tests for proteinuria and hematuria.

  • Potential alkaline urine pH, especially in cases involving Corynebacterium spp., due to their urease activity.

• Urine Culture:

  • Quantitative cultures to identify and determine the bacterial load, guiding antimicrobial therapy.

• Hematology:

  • Possible leukocytosis with a left shift, indicating an inflammatory response.

  • Anemia may be observed in chronic cases due to prolonged infection.

• Serum Biochemistry:

  • Elevated blood urea nitrogen (BUN) and creatinine levels in cases with significant renal involvement, indicating compromised kidney function.

These laboratory findings, in conjunction with clinical signs and imaging studies, facilitate a comprehensive diagnosis. Merck Veterinary Manual

Diagnosis

Diagnosis is based on clinical signs, hematuria, recent parturition history, and physical examination findings such as an enlarged, painful left kidney with loss of lobulation. Diagnostic tools include ultrasonography of the urinary tract, endoscopic inspection of the bladder, microscopic urine examination for white blood cells and bacteria, dipstick tests for proteinuria and hematuria, and quantitative urine cultures to identify causative organisms. It's important to note that the right kidney is generally not palpable per rectum, except for the caudal pole in certain breeds like Jersey cows and heifers. Merck Veterinary Manual

Treatment

Early and sustained antimicrobial therapy is essential for successful treatment. For infections caused by Corynebacterium spp., procaine penicillin is recommended at 22,000 IU/kg intramuscularly every 12 hours, or 44,000 IU/kg intramuscularly every 24 hours, for 3 to 4 weeks. Alternatively, trimethoprim-sulfadoxine can be administered at 16 mg/kg intramuscularly every 12 hours for the same duration. For E. coli infections, antimicrobial susceptibility testing guides appropriate therapy. Ceftiofur at 1.1–2.2 mg/kg intramuscularly or subcutaneously every 24 hours for 2 to 3 weeks, or gentamicin at 5–6 mg/kg intramuscularly every 24 hours for 5 to 7 days, have been used successfully. However, due to prolonged tissue depletion times, aminoglycosides like gentamicin are rarely indicated in food-producing animals. Manipulating urine pH may theoretically aid treatment, as E. coli thrives in acidic urine (pH < 7), while Corynebacterium spp. prefer alkaline urine (pH > 7). In cases where pyelonephritis is confined to one kidney and the animal is non-azotemic, unilateral nephrectomy may be beneficial. Affected animals should be isolated to prevent environmental contamination, and in herds with multiple cases, artificial insemination may be considered to reduce transmission risk. Merck Veterinary Manual

Key Points

• Bovine cystitis and pyelonephritis commonly occur postpartum in cattle.

• Clinical signs include hematuria, pyuria, and stranguria.

• Prolonged antimicrobial therapy (2–4 weeks) is typically effective in acute cases.