PRACTICAL: Pathology of the urinary tract Flashcards
Pathogenesis - hydronephrosis
- urine outflow obstruction increases pressure in renal pelvis –> compression of delicate tissue
- interstitial BVs collapse and RBF decreases –> hypoxia and ischaemic necrosis
- tubules degenerate and/or atrophy and necrosis –> replaced by interstitial fibrosis –> pale radiating columns/ rays
What does bilateral hydronephrosis suggest?
blockage affects both ureters or was at level of bladder neck or urethra. More serious than unilateral as causes renal failure.
Factors leading to hydronephrosis?
Obstructionofurineoutflowcausedby:
- intraluminal occlusion of urinary tract (calculi, mucous plugs, blood clots, neoplasia, inflammatory cells)
- external compression (neoplasia, inflammation, circumferential fibrosis, vaginal and/or uterine prolapse)
- congenital abnormalities (ureter aplasia, ectopic ureters)
- trauma
- bladder paralysis
What do indistinct pale striations in the inner zone of the cortex represent?
tubular degeneration and necrosis
What can polarised light show inside cells?
intratubular crystals (e.g. caused by antifreeze containing ethylene glycol)
Pathogenesis - antifreeze toxicity
- EG absorbed from GIT
- oxidised in liver (by alcohol dehydrogenase) to toxic metabolites including glycolic acid and oxalate
- these are filtered by glomeruli and directly cuase acute tubular necrosis
- formation and precipitation of calcium oxalate crystals in renal tubular lumens, tubular epithelial cells and the interstitium causes intrarenal obstruction and mechanical damage
How may herbivores succumb to similar condition as EG toxicity?
by consumption of oxalate-containing plants
Gross appearance - bovine pyelonephritis
renal calyces contain suppurative exudate bordered by red rim of haemorrhage
Pathogenesis - bovine pyelonephritis
- ascending infection (bladder)
- trauma during parturition
- stresses of parturition, peak lactation and a high-protein diet (latter increases urine pH which is conducive to bacterial colonisation of urinary tract)
Which infectious agents are associated with pyelonephritis in cattle?
- E. coli
- A. pyogenes
- C. renale
- Others (opportunisitc and environmental possible, including Staph and Strep)
What is urease?
- produced by E.coli and C. renale
- causes hydrolysis of urea releasing excessive ammonia which damages urinary tract mucosa and increases urine pH
Which spp are commonly affected by post-partum pyelonephritis?
- cattle
- sows
What is acute tubular necrosis?
necrosis of the tubular epithelial cells without reactive inflammation or scar tissue indicating recent death of cells
Causes - acute tubular necrosis
- ischaemia
- nephrotoxins
- inflammation
- certain infectious agents
T/F: tubular BMs are retained more consistently after toxic than ischaemic insults and are necessary for repair of necrotic tubules
True
How can cysts form in kidneys?
where fibrous CT compresses tubules causing dilation proximal to the obstruction
What is the toxic syndrome associated with chronic renal failure?
uraemia
Name lesions associated with chronic renal failure
- ulcerative stomatitis, gastritis, colitis
- mineralisation of gastric mucosa, intercostal parietal pleura and pulmonary parenchyma
- uraemic pneumonitis
- fibrous osteodystrophy
- parathyroid hyperplasia
- non-regenerative anaemia
What happens to glucose molecules in the bladder of DM animals?
- glucose split by bacteria (E.coli and C.perfringens) with release of CO2 into bladder lumen and subsequent absorption into bladder lymphatics
Which cystitis syndrome are cats particularly prone to?
- feline urologic syndrome (fine struvite crystals (sand) in a mucoid protein matrix fill the urethra and can cause obstructive urolithiasis
Define anisokaryosis
variation in nucleus size
Define anisocytosis
abnormal variation in size of RBCs
What might a TCC mass do if enlarged obstructing urine outflow?
- urine retention
- cystitis
- hydroureter
- hydronephrosis
- pyelitis
- pyelonephritis
What can infarcts occlude?
interlobar, arcuate or interlobular arteries –> obstructing blood supply to local parenchyma –> coagulative necrosis consequent to peracute ischaemia
What might precipitate renal infarcts?
thromboemboli could have formed from vegetative endocarditis affecting the mitral or aortic valves of the heart.
Gross appearance - suppurative glomerulitis or embolic nephritis
multifocal small pale white or red necrotic foci randomly scattered throughout the capsular surface and cortical surface
What are the necrotic foci in suppurative glomerulitis/ embolic nephritis?
microabscesses centered on glomeruli comprising bacteria, neutrophils and necrotic debris
What can cause microabscessation in foals, pigs and small ruminants?
- FOALS: Actinobaciullus equuli
- PIGS: Erysipelothrix rhusiopathie
- SMALL RUMINANTS: Corynebacterium pseudotuberculosis
Pathogenesis - suppurative glomerulitis or embolic nephritis
- causative bacteria enter the kidney via vasculature (bacteraemia) and lodge in capillaries of glomeruli, replicate, induce necrosis and inflammation
- in young animals, environmental bacteria could enter and disseminate from umbilicus or in lambs, from docking or castration wounds
- bacterial thromboemboli could form in any animal from bacterial endocarditis
If animal survives microabscessation of kidney, what will happen to the kidney?
microabscesses persist or gradually replaced by chronic inflammation (lymphocytes, PCs, macrophages) and eventually fibrous CT.
