Urinary Pathology

Question 1

What are mesangial cells?

Answer 1

• phagocytose macromolecules and immune complexes
• contract to autoregulate glomerular blood flow

Question 2

What are examples of non-urinary lesions associated with renal failure?

Answer 2

• gastric ulcers/uremic gastritis
• ulcerative glossitis/stomatitis
• mineralization of intercostal pleura - ‘uremic frosting’
• uremic pneumonitis - pulm edema/mineralization
• parathyroid hyperplasia
• anemia

Question 3

Why does parathyroid hyperplasia occur with renal failure?

Answer 3

• phosphate retention –> decr ionized Ca++ –> PTH release

Question 4

Describe polycystic kidney disease in cats

Answer 4

• autosomal dominant, defect of PKD1 gene
• Persians predisposed
• can dx @ 10 mo via U/S
• cysts can arise from any segment of nephron

Question 5

Describe polycystic kideny disease in other species

Answer 5

• 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

Question 6

Describe papillary necrosis

Answer 6

• 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

Question 7

Describe hydronephrosis/hydroureter

Answer 7

Hydronephrosis- dilation of renal pelvis/calyces

Hydroureter - dilation of ureters

• typically occurs secondary to obstruction

Question 8

What is glomerulonephritis?

Answer 8

• 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

Question 9

Characterization of glomerulonephritis is dependent on what?

Answer 9

• which parts of the glomerulus are affected
• whether there is immune complex deposition
• where immune complexes are deposited

Question 10

What is the pathogenesis of immune complex glomerulonephritis?

Answer 10

• 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

Question 11

What are some conditions commonly associated with immune complex glomerulonephritis?

Answer 11

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

Question 12

What might you see histologically with glomerulonephritis?

Answer 12

• thickened basement membranes
• increased #s of mesangial cells
• synechiae - adhesions b/t the glomerular tuft and the capsule

Question 13

What are the clinical features of acute renal failure?

Answer 13

• 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

Question 14

What are the clinical features of chronic renal failure?

Answer 14

• 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

Question 15

What is the clinicopathologic finding the most suggestive of glomerular disease?

Answer 15

proteinuria in the absence of hemorrhage or inflammation

*most sensitive way to measure is the urine protein to urine creatinine ratio

Question 16

Describe glomerular amyloidosis

Answer 16

• 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

Question 17

Describe embolic nephritis

Answer 17

• bacteria lodge mainly in glomerular and peritubular capillaries
  
  • Horses: Actinobacillus equuli
  • Pigs: Erysipelothrix rhusiopathiae
  • Cattle: Trueperella pyogenes

Question 18

What might you see histologically with tubular degeneration?

Answer 18

vacuolation of epithelial cells

Question 19

Waht might you see histologically with tubular necrosis?

Answer 19

• loss of cellular detail
• nuclear karyorrhexis, karyolysis, pyknosis
• incr cytoplasmic eosinophilia
• sloughing of epithelial cells

Question 20

What might you see histologically with tubular regeneration?

Answer 20

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

Question 21

Describe acute tubular (ischemic) injury

Answer 21

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

Question 22

Describe acute tubular toxic injury

Answer 22

Histologic lesions: extensive necrosis of predominantly proximal tubules, distal tubules sometimes; b.m may be preserved (scaffolding)

Question 23

List some examples of nephrotoxic substances

Answer 23

Animal venom, antimicrobials, chemo, cantharadin, contrast media, ethylene glycol, heavy metals, plants, mycotoxins

Question 24

Describe oxalate necrosis

Answer 24

Can be d/t ethylene glycol or oxalate containing plants (ie halogeton, greasewood, rhubarb, sorrel)

Question 25

Describe ethylene glycol toxicosis

Answer 25

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

Question 26

What is pigment nephrosis?

Answer 26

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

Question 27

Describe interstitial (tubulointerstitial) nephritis

Answer 27

acute cases - edema, leukocyte infiltration, focal tubular necrosis; chronic cases - leukocytic (usually lymphoplasmacytic) infiltrate, interstitial fibrosis, tubular atrophy

Question 28

What causes “white-spotted kidney” disease in calves?

Answer 28

Thought to be due to a prior bacteremia, usually E. Coli; nonsuppurative interstitial nephritis w/ fibrosis

Question 29

Describe the pathogenesis of leptospirosis

Answer 29

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

Question 30

Describe canid herpesvirus 1

Answer 30

* 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

Question 31

Describe pyelonephritis

Answer 31

* **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

Question 32

What are two parasites involved in renal disease?

Answer 32

* **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

Question 33

What are examples of renal neoplasms?

Answer 33

* 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

Question 34

What are a few examples of congenital urinary tract abnormalities?

Answer 34

* 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_

Question 35

Describe urolithiasis

Answer 35

* 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

Question 36

Describe bacterial cystitis

Answer 36

* 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

Question 37

What is emphysematous cystitis?

Answer 37

* seen rarely in diabetic animals d/t bacterial fermentation of urinary glucose into carbon dioxide; E. coli most common

Question 38

What are some neoplasms of the lower urinary tract?

Answer 38

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