- Definition
- Pathophysiology
- Systems Affected
- Genetics
- Incidence/Prevalence
- Geographic Distribution
- Signalment
- Signs
- Causes
- Risk Factors
BASICS
- Most commonly ascending infections secondary to stasis of urine flow (as with bladder paralysis) and vesiculoureteral reflux (retrograde flow of urine into ureters) or damage to renal parenchyma (i.e. polycystic disease and medullary necrosis)
- Less commonly a result of neonatal septicemia
- Usually a consequence of abnormal urine flow (anatomic or functional), especially bladder paralysis
- Frequently accompanied by urolithiasis
- Halicephalobus gingivalis (deletrix) infection (rare) can be life-threatening owing to central nervous system involvement. Large granulomatous lesions full of rhabditiform nematodes usually are found in the kidneys. Renal involvement typically is inapparent but may cause hematuria
- Dioctophyma renale. Typical hosts are carnivorous species, but horses can ingest the intermediate host (annelid worm) while grazing or drinking natural water. The parasite may live 1–3 years in the kidney, shedding eggs in the urine. The renal parenchyma is completely destroyed, and death of the parasite leads to fibrosis of the kidney
- Occasionally, hydronephrosis or renal hemorrhage may be a serious complication of parasitic infection
- Infection with the coccidian parasite Klossiella equi is common, but clinically benign, and thus an incidental finding
Recumbent foals on broad-spectrum antibiotics may develop secondary Candida spp. cystitis.
- Renal/urologic—infection and failure (with bilateral upper UTI)
- Nervous—with H. gingivalis infection
- Dermatologic—urine scalding of hindlimbs
- Bacterial UTIs are uncommon
- Clinically significant renal nematode infections are rare, despite necropsy surveys revealing that up to 20% of equine kidneys have evidence of Strongylus vulgaris migration
- One necropsy survey found K. equi in 12% of horses examined
- Foals <30 days of age are at greater risk for septic nephritis associated with septicemia
- Critically ill neonates receiving broad-spectrum antibiotic treatment may develop ascending UTI with Candida spp.
- Upper UTI—usually weight loss or fever of undetermined origin; less commonly, hematuria or pyuria. Occasionally, recurrent colic when associated with urolithiasis
- Lower UTI—dysuria (e.g. pollakiuria, stranguria, hematuria). Urinary incontinence and skin scalding may be observed with either bladder paresis or pollakiuria
- Lethargy, fever, partial anorexia, intermittent colic, and mild dehydration
- Rectal examination may reveal enlarged ureters and kidneys
- Occasionally, obstructing ureteroliths can be palpated
- Dysuria with or without urine scalding, but general health usually is good
- Rectal examination—thickened bladder wall; cystoliths or other bladder masses may be detected if bladder is not full. Assess for bladder paresis (i.e. large atonic bladder with incontinence produced by compressing bladder) versus a small bladder usually present with pollakiuria
- Bacterial ascending infections—Escherichia coli, Proteus mirabilis, Klebsiella spp., Staphylococcus spp., Enterobacter spp., Corynebacterium spp., and Pseudomonas aeruginosa. Mixed infections may be seen
- Less commonly, hematogenous infection—Rhodococcus equi, Actinobacillus equuli, and other Gram-negative bacteria
- Parasitic infection (see Pathophysiology)
- Ascending infections
- Organisms similar to those causing upper UTIs
- Chronic antibiotic treatment or instrumentation of the urinary tract (indwelling bladder catheters, ureteral stents) may cause UTI with Enterococcus spp. or other antibiotic-resistant microbes
- Yeast infection (see Pathophysiology)
- Outbreaks of cystitis described with eating hybrids of Sorghum spp. (Johnson grass, sudangrass) in the southwestern USA, likely a complication of bladder paralysis
- Outbreak of cystitis, manifested by hematuria more than UTI or incontinence, in western Australia. A fungal toxin produced by Pithomyces chartarum was suspected
- Vesiculoureteral reflux, which may develop with bladder paresis or partial obstruction, predisposing for ascending upper UTI
- Abnormal urine flow, especially with bladder paralysis, increases risk for lower UTI
- Use of indwelling catheters is a significant risk factor, but routine instrumentation of the urinary tract (bladder catheterization, cystoscopy) is relatively low risk
- Dystocia and subsequent trauma to the lower urinary tract may allow ascending infections
DIAGNOSIS
TREATMENT
MEDICATIONS
FOLLOW-UP
MISCELLANEOUS