L5: Path of the Urinary System (Farina) Flashcards
functional unit of kidney
nephron
renal dz may affect:
glomeruli, tubules, interstitium and/or blood vessels
glomeruli fx
- selective filter for molecules based on size, charge, and shape
- mesangial cells phagocytose macromolecules and immune complexes; contract to autoregulate glomerula blood flow
tubules fx
- selectively secrete or reabsorb water and organic/inorganic solutes
- can regenerate as long as BM remains intact for scaffolding for regenerating epithelial cells
endocrine fxs of the kidney: erythropoietin
- stimulates erythrocyte production
- prod. by endothelial cells
endocrine fxs of the kidney: renin
-released in response to Na depletion or low blood V. converts angiotensinogen to angiotensin I
vitamin D action occurs in what organ
kidney
horseshoe kidney
kidneys fused at one pole, roughly near midline
polycystic kidney disease (PKD)
- autosomal dominant**
- ~38% of Persian cats affected
- also see hepatic cysts in a few cases
- kidney dysfx at 3-10yo
- 98% cases can be diagnosed at U/S at 10mo
- arise from any segment of the nephron
papillary necrosis
- common in horses (esp. in dehydrated horses treated with bute)
- NSAIDs** inhibit prostaglandin synthase –> dec. production of PGE2, (which maintains vasodilation in juxtamedullary nephrons) –> ischemia and subsequent necrosis
hydronephrosis
dilation of renal pelvis/calyces
-typically occurs 2ary to obstruction
hydroureter
dilation of ureters
-typically occurs 2ary to obstruction
glomerulonephritis path.
- circulating immune complexes deposited in or adjacent to glomerular BM or Ab formed against glomerular BM
- immune complexes may be deposited subendothelially, in the BM, or subepithelially
- IC best formed in conditions with slight Ag excess
- complement fixation, leukocytic infiltration and prod. of inflamm. mediators by mesangial cells may contribute to glomerular injury
- filtration barrer becomes compromised –> protein loss to urine
types of glomerulonephritis (GN)
1) Membranous: thickened glomerular BM
2) Proliferative: inc. numbers of mesangial cells
3) Membranoproliferative: combo of 1 and 2
conditions commonly assoc. with GN
Chronic Inflammatory stimuli:
- viral diseases
- chronic bacterial infections
- parasitic and protozoal diseases
- autoimmune diseases
- neoplasms
Glomerular amyloidosis
- usually reactive systemic amyloidosis
- can be assoc. with chronic inflamm. or idiopathic origin
- Shar Peis, Abyssinian cats
- extensive amyloid deposition –> compromise of the filtration barrier –> proteinuria
- progressive renal insufficiency and proteinuria
amyloid
- derived from serum amyloid A (SAA), an acute phase protein
- stained with Lugol’s iodine (brown) or Congo red
Embolic nephritis/glomerulitis
- bacteria lodge mainly in glomerular and peritubular capillaries –> microabscess
- usually limited to cortex
- horse: Actinobacillus equuli most common cause
- pig: Erysipelothric rhusiopathiae
- cattle: Trueperella pyogenes
Acute tubular necrosis - ischemic
- due to hypotension (shock)
- focal necrosis along nephrons, esp. proximal tubules
- distal tubules may also be affected
- glomeruli usually unaffected
- disruption of tubular BM –> no scaffolding for tubular epithelial regeneration
Acute tubular necrosis - toxic
- tubules, esp. proximal tubules, very susceptible to a variety of toxins due to high metabolic activity and exposure to agents in large volume of ultrafiltrate they resorb**
- leads to necrosis of proximal tubules +/- distal tubules
- BM PRESERVED
tubular degeneration
- vacuolization of epithelial cells
- gives moth-eaten appearance
tubular necrosis**
- loss of cellular detail
- nuclear karyorrhexis (nuclei small and dark), karyolysis (nucleus breaking apart), pyknosis (can’t see nucleus anymore)
- inc. cytoplasmic eosinophilia
- sloughing of epithelial cells
tubular regeneration chars.**
- increased cytoplasmic basophilia
- piling/crowding of epithelial cells
- nuclei with an open chromatin pattern and prominent nucleoli
- mitotic figures
Interstitial (tubulointerstitial) nephritis
- chronic form common in older animals; cause usually not evident in these cases
- acute cases: edema, leukocyte infiltration, focal tubular necrosis
- chronic cases: leukocytic infiltrate, interstitial fibrosis, tubular atrophy
leptospirosis affects what areas of kidney**
tubules, interstitium
pyelonephritis
- inflamm. of renal pelvis and parenchyma
- usually results from ascending infection from the lower urinary tract, so usually concurrent ureteritis and cystitis
- infectious agents similar to those that cause lower UTI
- vesicoureteral reflex –>
vesicoureteral reflux
retrograde flow up ureters during micturition
Causes of Parasitic renal disease
Stephanurus dentatus (kidney worm in pigs) --> encyst in perirenal tissue, communicate with renal pelvis for passage of eggs Dioctophyma renale (giant kidney worm; minks, dogs, cats after eating fish) --> progressive destruction of renal parenchyma
Renal Neoplasia: Adenoma
- benign tumors from tubular epithelium**
- usually small, single nodules, incidental findings
Renal Neoplasia: Adenocarcinoma
- most common primary renal tumors in sheep, cattle, dogs**
- usually well-demarcated, compress remaining renal parenchyma, located at one pole of kidney
Renal Neoplasia: Nephroblastoma
- most common primary renal tumor of pigs and chickens** (also in fish)
- usually in young animals
- histo: primitive glomeruli, tubules and mesenchyme; may contain cartilage, bone, fat
lymphosarcoma most common neoplasm to met to kidney**
:)
non-urinary lesions assoc. with renal failure
- gastric ulcers/uremic gastritis
- ulcerative glossitis/stomatitis
- mineralization of intercostal pleura
- uremic pneumonitis
- parathyroid hyperplasia
- anemia
Congenital Abnormalities
- Ectopic ureter
- patent urachus (esp. foals)
Urolithiasis
- calculi in urinary passages (anywhere from renal pelvis to urethra)
- predisposing factors: urine pH, hereditary factors, diet, UTIs
Cystitis
- bacteria from ascending infection from urethra (almost always rectal flora)
- predisposing factors: loss of normal voiding mech, loss of acidic pH, glucosuria, proteinuria, mucosal trauma
- females predisposed (wide/short urethra)
emphysematous cystitis
- rarely see in diabetic animals due to bacterial fermentation of urinary glucose into CO2
- E. coli most common
enzootic hematuria
- mature cattle w/ persistent hematuria w/ hemorrhage and/or neoplasms in lower UT
- chronic ingestion of toxic bracken fern
- neoplasms include TCC, SCC, papilloma, fibroma/sarcoma, hemangioma/sarcoma, leiomyosarcoma
neoplasia of the lower UT
Papilloma
-may become malignant TCC in dogs
TCC
-most often in bladder neck or trigone**; 50% met
Botyroid Rhabdomyosarcoma
-young large or giant breeds
-forms in skeletal m., which isn’t present in BL of adult dogs
