Urinary Pathology Flashcards
What are mesangial cells?
- phagocytose macromolecules and immune complexes
- contract to autoregulate glomerular blood flow
What are examples of non-urinary lesions associated with renal failure?
- gastric ulcers/uremic gastritis
- ulcerative glossitis/stomatitis
- mineralization of intercostal pleura - ‘uremic frosting’
- uremic pneumonitis - pulm edema/mineralization
- parathyroid hyperplasia
- anemia
Why does parathyroid hyperplasia occur with renal failure?
- phosphate retention –> decr ionized Ca++ –> PTH release
Describe polycystic kidney disease in cats
- autosomal dominant, defect of PKD1 gene
- Persians predisposed
- can dx @ 10 mo via U/S
- cysts can arise from any segment of nephron
Describe polycystic kideny disease in other species
- congenital PKD w/ an unknown inheritance can occur in all domestic mammals
- animals are typically stillborn or die of renal failure in first few weeks of life
- enlarged kidneys w/ numerous 1-5 mm diameter cysts
- can have concurrent biliary and/or panc cysts
Describe papillary necrosis
- common in horses (esp in dehydrated horses treated w/ bute)
- NSAIDs inhibit COX–>decr PGE2 production
- PGE2 maintains vasodilation in arterioles, loss of this –> ischemia and subsequent necrosis
Describe hydronephrosis/hydroureter
Hydronephrosis- dilation of renal pelvis/calyces
Hydroureter - dilation of ureters
- typically occurs secondary to obstruction
What is glomerulonephritis?
- alteration of structure of glomerulus involving one or more of the following: basement membranes, mesangial matrix, mesangial cells, immune complex deposition
- end result: alter the filtration barrier–> protein loss, decr GFR –> renal failure
Characterization of glomerulonephritis is dependent on what?
- which parts of the glomerulus are affected
- whether there is immune complex deposition
- where immune complexes are deposited
What is the pathogenesis of immune complex glomerulonephritis?
- circulating immune complexes deposited in/adjacent to glomerular b.m. or antibodies formed against the glomerular b.m.
- immune complexes may be deposited subendothelially, in the b.m. or subepithelially
- complement fixation, leukocytic infiltration and production of inflammatory mediators by mesangial cells may contribute glomerular injury
- filtration barrier becomes compromised –> protein loss
What are some conditions commonly associated with immune complex glomerulonephritis?
- viral dz
- chronic bacterial infections
- parasitic and protozoal dz
- autoimmune dz
- neoplasms
What might you see histologically with glomerulonephritis?
- thickened basement membranes
- increased #s of mesangial cells
- synechiae - adhesions b/t the glomerular tuft and the capsule
What are the clinical features of acute renal failure?
- good body condition
- smooth, enlarged kidneys (+/- painful)
- PCV normal to incr
- K+ normal to incr
- more severe metabolic acidosis
- relatively severe clinical signs relative to bloodwork
What are the clinical features of chronic renal failure?
- poor body condition
- small irregular kidneys
- nonregenerative anemia
- K+ normal to decr
- less severe metabolic acidosis
- relatively mild clinical signs relative to bw
- longstanding PU/PD
What is the clinicopathologic finding the most suggestive of glomerular disease?
proteinuria in the absence of hemorrhage or inflammation
*most sensitive way to measure is the urine protein to urine creatinine ratio
Describe glomerular amyloidosis
- often reactive systemic amyloidosis
- assoc w/ chronic inflammation
- common in Shar Peis and Abyssinian cats
- extensive glomerular amyloid deposition leads to compromise of the filtration barrier and proteinuria
- develop progressive renal insufficiency and proteinuria
Describe embolic nephritis
- bacteria lodge mainly in glomerular and peritubular capillaries
- Horses: Actinobacillus equuli
- Pigs: Erysipelothrix rhusiopathiae
- Cattle: Trueperella pyogenes
What might you see histologically with tubular degeneration?
vacuolation of epithelial cells
Waht might you see histologically with tubular necrosis?
- loss of cellular detail
- nuclear karyorrhexis, karyolysis, pyknosis
- incr cytoplasmic eosinophilia
- sloughing of epithelial cells
What might you see histologically with tubular regeneration?
- increased cytoplasmic basophilia
- piling/crowding of epithelial cells
- nuclei with an open chromatin pattern and prominent nucleoli
- mitotic figures
Describe acute tubular (ischemic) injury
Due to hypotension; mild - degeneration/necrosis of primarily tubules; prolonged ischemia- renal cortical necrosis, affects all cortical structures; disruption of b.m can occur —> no scaffolding for tubular epithelial regeneration
Describe acute tubular toxic injury
Histologic lesions: extensive necrosis of predominantly proximal tubules, distal tubules sometimes; b.m may be preserved (scaffolding)
List some examples of nephrotoxic substances
Animal venom, antimicrobials, chemo, cantharadin, contrast media, ethylene glycol, heavy metals, plants, mycotoxins
Describe oxalate necrosis
Can be d/t ethylene glycol or oxalate containing plants (ie halogeton, greasewood, rhubarb, sorrel)
Describe ethylene glycol toxicosis
Major component of antifreeze; fluorescein dye added to it to help detect a radiator leak - urine of animals with acute toxicosis might fluoresce w/ black light; calcium oxalate crystals precipitate in renal tubules and cause tubular necrosis
What is pigment nephrosis?
Myoglobin and hemoglobin can cause tubular injury - myoglobin from mm damage and hemoglobin from hemolytic anemias; cannot distinguish Hb and Mb casts in kidney on light microscopy
Describe interstitial (tubulointerstitial) nephritis
acute cases - edema, leukocyte infiltration, focal tubular necrosis; chronic cases - leukocytic (usually lymphoplasmacytic) infiltrate, interstitial fibrosis, tubular atrophy
What causes “white-spotted kidney” disease in calves?
Thought to be due to a prior bacteremia, usually E. Coli; nonsuppurative interstitial nephritis w/ fibrosis
Describe the pathogenesis of leptospirosis
Caused by serovars of L. Interrogans, contact w/ infected fluid (often urine), bacteria can enter via mucous membranes or wet skin —> abortion, stillbirth, hepatitis, nephritis, meningitis, septicemia; renal failure most common in dogs, pigs - extensive interstitial nephritis (not renal failure); histo: tubular degeneration/necrosis, interstitial/tubulointerstitial nephritis
Describe canid herpesvirus 1
- often fatal for newborn puppies, can also cause abortion and stillbirth
- puppies generally need to be exposed before 2 wks of age - die within 2d of showing signs
- C/S: anorexia, vomiting, abd pain
- Gross lesions: foci of hemorrhage and necrosis in mult. organs, esp kidney
Describe pyelonephritis
- inflammation of the renal pelvis and parenchyma
- usually results from ascending infection from lower urinary tract, so patients typically have concurrent ureteritis and cystitis
- vesiculouerteral reflux - retrograde flow up ureters during micrturition
What are two parasites involved in renal disease?
-
Stephanurus dentatus - kidney worm in swine that encyst in perirenal tissue
- these cysts communicate w/ the renal pelvis to allow for passage of eggs
-
Dioctophyma renale - giant kidney worm, usually in piscovorous mammals (mink, dogs, cats); adults live in renal pelvis and are very destructive
- cause progressive destruction of renal parenchyma
What are examples of renal neoplasms?
- Adenomas: benign tumors of tubular epithelium
- Adenocarcinomas: most common primary renal tumors in horses, cattle and dogs; usually well-demarcated, compress remaining renal parenchyma, located at one pole
- Nephroblastomas: most common primary renal tumor of pigs and chickens, usually occurs in young animals
- Histo: primitive glomeruli, tubules and mesenchyme, may contain cartilage, bone or fat
- Metastatic lymphoma very common
What are a few examples of congenital urinary tract abnormalities?
- Ectopic ureters - ureters can empty into bladder neck, urethra, vagina, vas deferens or seminal vesicles; may be uni- or bilateral; certain predisposed breed
- Patent urachus - failure of closure of the urachal lumen results in dribbling of urine from the urachus; most common in foals
Describe urolithiasis
- calculi in urinary passages, may be located from renal pelvis to urethra
- calculogenic substances must be present in sufficient concentration
- predisposing factors:
- urine pH (precipitation)
- water intake
- hereditary factors (dalmatians)
- dietary factors
- UTIs
- male sex
Describe bacterial cystitis
- bacteria from ascending infection from urethra, almost always rectal flora
- predisposing factors:
- female
- loss of normal voiding mechanisms
- loss of acidic urine pH (carnivores)
- glucosuria
- proteinuria
- mucosal trauma
What is emphysematous cystitis?
- seen rarely in diabetic animals d/t bacterial fermentation of urinary glucose into carbon dioxide; E. coli most common
What are some neoplasms of the lower urinary tract?
Papilloma - covered by well-differentiated transitional epithelium, May undergo malignant transformation to TCC in dogs; transitional (urothelial) cell carcinoma - most often in bladder neck or trigone, 50% met.; botyroid rhabdomyocsarcoma - young (usually <18 mo) large or giant breed dogs
