L5: Path of the Urinary System (Farina)

Question 1

functional unit of kidney

Answer 1

nephron

Question 2

renal dz may affect:

Answer 2

glomeruli, tubules, interstitium and/or blood vessels

Question 3

glomeruli fx

Answer 3

• selective filter for molecules based on size, charge, and shape
• mesangial cells phagocytose macromolecules and immune complexes; contract to autoregulate glomerula blood flow

Question 4

tubules fx

Answer 4

• selectively secrete or reabsorb water and organic/inorganic solutes
• can regenerate as long as BM remains intact for scaffolding for regenerating epithelial cells

Question 5

endocrine fxs of the kidney: erythropoietin

Answer 5

• stimulates erythrocyte production

- prod. by endothelial cells

Question 6

endocrine fxs of the kidney: renin

Answer 6

-released in response to Na depletion or low blood V. converts angiotensinogen to angiotensin I

Question 7

vitamin D action occurs in what organ

Answer 7

kidney

Question 8

horseshoe kidney

Answer 8

kidneys fused at one pole, roughly near midline

Question 9

polycystic kidney disease (PKD)

Answer 9

• 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

Question 10

papillary necrosis

Answer 10

• 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

Question 11

hydronephrosis

Answer 11

dilation of renal pelvis/calyces

-typically occurs 2ary to obstruction

Question 12

hydroureter

Answer 12

dilation of ureters

-typically occurs 2ary to obstruction

Question 13

glomerulonephritis path.

Answer 13

• 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

Question 14

types of glomerulonephritis (GN)

Answer 14

1) Membranous: thickened glomerular BM
2) Proliferative: inc. numbers of mesangial cells
3) Membranoproliferative: combo of 1 and 2

Question 15

conditions commonly assoc. with GN

Answer 15

Chronic Inflammatory stimuli:

• viral diseases
• chronic bacterial infections
• parasitic and protozoal diseases
• autoimmune diseases
• neoplasms

Question 16

Glomerular amyloidosis

Answer 16

• 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

Question 17

amyloid

Answer 17

• derived from serum amyloid A (SAA), an acute phase protein

- stained with Lugol’s iodine (brown) or Congo red

Question 18

Embolic nephritis/glomerulitis

Answer 18

• 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

Question 19

Acute tubular necrosis - ischemic

Answer 19

• 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

Question 20

Acute tubular necrosis - toxic

Answer 20

• 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

Question 21

tubular degeneration

Answer 21

• vacuolization of epithelial cells

- gives moth-eaten appearance

Question 22

tubular necrosis**

Answer 22

• 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

Question 23

tubular regeneration chars.**

Answer 23

• increased cytoplasmic basophilia
• piling/crowding of epithelial cells
• nuclei with an open chromatin pattern and prominent nucleoli
• mitotic figures

Question 24

Interstitial (tubulointerstitial) nephritis

Answer 24

• 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

Question 25

leptospirosis affects what areas of kidney**

Answer 25

tubules, interstitium

Question 26

pyelonephritis

Answer 26

- 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 -->

Question 27

vesicoureteral reflux

Answer 27

retrograde flow up ureters during micturition

Question 28

Causes of Parasitic renal disease

Answer 28

``` 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 ```

Question 29

Renal Neoplasia: Adenoma

Answer 29

- benign tumors from tubular epithelium** | - usually small, single nodules, incidental findings

Question 30

Renal Neoplasia: Adenocarcinoma

Answer 30

- most common primary renal tumors in sheep, cattle, dogs** | - usually well-demarcated, compress remaining renal parenchyma, located at one pole of kidney

Question 31

Renal Neoplasia: Nephroblastoma

Answer 31

- 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

Question 32

lymphosarcoma most common neoplasm to met to kidney**

Answer 32

:)

Question 33

non-urinary lesions assoc. with renal failure

Answer 33

- gastric ulcers/uremic gastritis - ulcerative glossitis/stomatitis - mineralization of intercostal pleura - uremic pneumonitis - parathyroid hyperplasia - anemia

Question 34

Congenital Abnormalities

Answer 34

- Ectopic ureter | - patent urachus (esp. foals)

Question 35

Urolithiasis

Answer 35

- calculi in urinary passages (anywhere from renal pelvis to urethra) - predisposing factors: urine pH, hereditary factors, diet, UTIs

Question 36

Cystitis

Answer 36

- 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)

Question 37

emphysematous cystitis

Answer 37

- rarely see in diabetic animals due to bacterial fermentation of urinary glucose into CO2 - E. coli most common

Question 38

enzootic hematuria

Answer 38

- 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

Question 39

neoplasia of the lower UT

Answer 39

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