Pathology of kidneys and lower UTI Flashcards
What are the 2 sources of infectious diseases of the kidneys?
Haematogenous (descending)
Urinary (ascending)
What are the possible causes (aetiology) of infectious kidney disease?
Viral e.g., canine herpesvirus, canine adenovirus
Bacterial e.g., leptospira interrogans
Parasitic e.g., toxocara canis
What are the histopathological classifications of infectious kidney disease?
Non-suppurative tubulointerstitial nephritis
Suppurative interstitial nephritis
What are the types of non-suppurative tubulointerstitial nephritis?
Acute interstitial nephritis
Chronic interstitial nephritis
Describe the appearance of acute interstitial nephritis
Swollen, pale kidneys with random grey mottling of the capsular surface
Lympho-histiocytic inflammation:
- interstitial oedema
- mononuclear infiltration
- tubular degeneration and necrosis
Describe the appearance of chronic interstitial nephritis
fibrotic kidneys
Lympho-histiocytic inflammation:
- mononuclear cells infiltration (lymphocytes, plasma cells, histiocytes)
- Interstitial fibrosis
- generalised tubular atrophy
Give examples of aetiologies of non-suppurative tubulointerstitial nephritis
leptospira interrogans
Escherichia coli
Feline infectious peritonitis virus
Canine herpesvirus
What are the classifications of suppurative interstitial nephritis?
Embolic nephritis (Haematogenous)
Pyelonephritis (Ascending)
Describe suppurative embolic nephritis
Bacteraemia => showers of septic emboli that lodge in capillaries (predominantly glomerular and peritubular capillaries) and produce variably sized abscesses.
Larger emboli lodge in arteries, producing uni or bilateral septic infarcts (tissue death)
Give examples of aetiologies of suppurative embolic nephritis
actinobacillis equuli
trueperella pyogenes
Describe the pathogenesis of pyelonephritis
Ascending, due to vesicoureteral reflux
begins with establishment of infeciton in the lower urinary tract
Describe the gross appearance of pyelonephritis
Pelvic mucosa can be inflamed, thickened and coated with exudate
Papillae are often ulcerated and necrotic
Renal involvement is notable by irregular, radially orientated, red or grey streaks involving the medulla
Describe the microscopic appearance of pyelonephritis
transitional epithelium is necrotic and sloughed, covered by debris and fibrin, neutrophils and bacterial colonies
Medullary tubules are dilated and the lumina contain neutrophils and bacterial colonies
Chronic lesions have severe fibrosis
Give examples of aetiologies of pyelonephritis
E. coli
Staphylococci
Streptococci
enterobacter
proteus
pseudomonas
What are the 2 sources of lower urinary tract infection?
descending (nephritis or pyelonephritis)
Ascending
What are the different types of lower urinary tract infections?
Ureteritis (rare in absence of cystitis)
Cystitis (bladder)
Urethritis (usually associated with obstruction by a calculus or urethral plug)
Describe the aetiology of cystitis
Bacteria ascending from the urethra - normally rectal or cutaneous flora
Most common:
- E. coli
- proteus vulgaris
- streptococci
- staphylococci
- enterococci
What are the predisposing factors of cystitis?
Stagnation of urine due to obstruction or incomplete bladder emptying
urothelial trauma (uroliths)
catheterisation
vaginoscopy
urinary incontinence
vaginitis
diabetes mellitus
antibiotics or corticosteroids
hyperoestrogenism
immunodepression
gender (shorter urethra in females)
malformations
comorbidities e.g., pyometra
What are the defence mechanisms to cystitis?
urothelial barrier
pH
urine osmolality
IgA + IgG
Shedding of urothelium
Tamm-Horsfall mucoprotein
Describe the gross pathology of acute cystitis
haemorrhagic
catarrhal (inflammation of mucous membranes)
Fibrinopurulent
Necrotising
ulcerative
Describe the gross appearances of chronic cystitis
Associated with chronic bacterial infection and/or urolithiasis:
- diffuse
- polypoid
- follicular
Associated with glycosuria:
- emphysematous (gas accumulates in wall of bladder)
Describe the histopathology of acute cystitis
Acute ulcerative cystitis:
- ulceration
- inflammatory infiltration
- hyperaemia (increased blood)
Describe the histopathology of chronic follicular cystitis
aggregate of proliferating lymphocytes forming a lymphoid follicles
Describe the histopathology of chronic polypoid cystitis
polyp (villus-like projection) is covered in epithelium over a core of proliferated connective tissue densely infiltrated by inflammatory cells, haemorrhage and hemosiderin (brown, iron containing pigment)
Give examples of non-infectious cystitis
Dog and cat: sterile haemorrhagic cystitis (caused by cyclophosphamide)
HOrse: cantharidin toxicity (ingestion of blister beetle)
Cattle: enzootic haematuria (brackern fern)
Feline interstitial cystitis (multifactorial)
