Most infectious diseases of the urinary system in small animals are aerobic bacterial infections (see figure Bacterial species prevalence, dogs and cats; 1, 2, 3, 4, 5, 6, 7). Fungal, viral, and parasitic diseases of the urinary tract occur but are uncommon.
Infections can occur at any site within the urinary tract, including the urinary bladder (eg, bacterial cystitis). Bacteria that ascend from the lower urinary tract can cause an infection of the kidney (pyelonephritis) or prostate (bacterial prostatitis).
Courtesy of Dr. William Whitehouse.
Leptospirosis is a bacterial disease that causes injury to the kidneys and some other organs. Acute interstitial nephritis (also known as tubulointerstitial nephritis) in dogs is caused most often by Leptospira spp. Clinical leptospirosis is uncommon in cats; however, exposure and shedding may be similar in cats and dogs.
Most other infectious diseases affecting the kidneys cause glomerulonephritis through immune complex deposition (ie, immune-complex glomerulonephritis), so these are not true urinary tract infections. Renal biopsy is needed to diagnose the type of glomerular disease.
Toxoplasmosis can cause pyogranulomas in the kidneys or elsewhere in the urinary system. Systemic infectious diseases that cause vasculitis in cats or dogs (eg, feline infectious peritonitis, Rocky Mountain spotted fever) can also cause kidney disease.
Urinary tract infections can cause a urinary storage disorder leading to urinary incontinence, which must be distinguished from urinary incontinence from voiding disorders. In brief, disorders of urine storage are characterized by inappropriate leakage of urine due to urethral incompetence, anatomical defects, or instability of the detrusor muscle, whereas voiding disorders may involve inappropriate leakage of urine secondary to a functional or mechanical outflow obstruction (eg, overflow incontinence).
Key Points
Leptospirosis is an important cause of acute kidney injury in dogs.
Gram-negative bacteria are the most common organisms causing urinary tract infections in dogs and cats.
Immune-complex glomerulonephritis is associated with many infectious diseases, and renal biopsy is required for a definitive diagnosis.
For More Information
Sykes JE, Francey T, Schuller S, Stoddard RA, Cowgill LD, Moore GE. Updated American College of Veterinary Internal Medicine (ACVIM) consensus statement on leptospirosis in dogs. J Vet Intern Med. 2023;37(6):1966-1982.
Littman MP, Gerber B, Goldstein RE, Labato MA, Lappin MR, Moore GE. American College of Veterinary Internal Medicine (ACVIM) consensus update on Lyme borreliosis in dogs and cats. J Vet Intern Med. 2018;32(3):887-903.
Littman MP, Daminet S, Grauer GF, Lees GE, van Dongen AM; IRIS Canine GN Study Group Diagnosis Subgroup. Consensus recommendations for the diagnostic investigation of dogs with suspected glomerular disease. J Vet Intern Med. 2013;27(s1)S19-S26.
Goldstein RE, Brovida C, Fernandez-Del Palacio MJ, et al; IRIS Glomerular Disease Study Group. Consensus recommendations for treatment for dogs with serology positive glomerular disease. J Vet Intern Med. 2013;27(s1)S60-66.
References
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Wong C, Epstein SE, Westropp JL. Antimicrobial susceptibility patterns in urinary tract infections in dogs (2010-2013). J Vet Intern Med. 2015;29(4):1045-1052. doi:10.1111/jvim.13571
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Teichmann-Knorrn S, Reese S, Wolf G, Hartmann K, Dorsch R. Prevalence of feline urinary tract pathogens and antimicrobial resistance over five years. Vet Rec. 2018;183(1):21. doi:10.1136/vr.104440
Litster A, Moss SM, Honnery M, Rees B, Trott DJ. Prevalence of bacterial species in cats with clinical signs of lower urinary tract disease: recognition of Staphylococcus felis as a possible feline urinary tract pathogen. Vet Microbiol. 2007;121(1-2):182-188. doi:10.1016/j.vetmic.2006.11.025
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