Urinary Pathology Flashcards
What are the top five things the kidney does?
- Formation of urine to eliminate waste
- Acid-base regulation (bicarb)
- Sodium water balance (along with P and Ca)
- Maintaining potassium
- Endocrine functions (EPO production, Renin-angiotensin, Vitamin D conversion to active form)
T/F: Dog kidneys do not have a renal pelvis
F (cows do not)
What is the function of the proximal convoluted tubule?
Resorption of Na, Cl, K, albumin, glucose (should be all of it), and water; phosphorus can be absorbed but often is not
What is the basic function of the Loop of Henle?
Concentration of urine (resorption of water)
What is the function of the distal convoluted tubule?
Resorption of osmolytes and water
What is the function of the collecting duct?
Movement of water, urea, Na, Cl, H, and bicarb
Glomerular injury leading to decreased GFR affects the rest of the nephron by way of ___
Ischemia; inflammation
T/F: End stage kidney can only result from glomerular injury
F (glomerular or tubular)
Define acute renal failure
Rapid decrease in renal function over a short period of time (kidney is pale and swollen)
Define chronic renal failure
Decline in renal function over time with replacement of nephrons with fibrosis (end stage kidney)
Define azotemia
Increase of nitrogenous waste products in the blood (urea and creatinine); increased BUN and creatinine
What helps determine if azotemia is due to kidney dysfunction?
USG
Define uremia
Retention of nitrogenous waste products leading to multisystemic lesions (neuro and GI in dog)
What is a prerenal cause of acute renal failure?
Ischemia (shock)
What are three renal causes of acute renal failure?
Tubular necrosis from infectious agents (Leptospira)
Tubular necrosis from nephrotoxic drugs (aminoglycosides)
Tubular necrosis from chemicals (ethylene glycol)
What is a postrenal cause of acute renal failure?
Obstructive nephropathy (urolithiasis)
T/F: Retention of potassium in renal failure can lead to heart failure
T
T/F: Renal failure leads to metabolic alkalosis
F (metabolic acidosis)
T/F: Renal failure can lead to pulmonary edema
T (fluid therapy, kidney cannot regulate water balance)
Reduced erythropoietin production in renal failure leads to ___ anemia
Nonregenerative
As GFR is reduced, secretion by the kidneys is reduced, leading to ___
Hyperphosphatemia
Hyperphosphatemia leads to ___
Renal secondary hyperparathyroidism
T/F: Small, pitted kidneys that are scarred and have lost most of their nephrons are called end-stage kidneys
T
T/F: Nephrons are regenerative
F
T/F: Nephrons will hypertrophy to make up for the loss of other nephrons
T
What proportion of nephrons must be lost before alteration in urine concentration is seen?
2/3
What proportion of nephrons must be lost before azotemia is seen?
3/4
T/F: Creatinine elevation is easily detected in renal failure
F (range is so broad and increase is gradual)
T/F: Etiology of end stage kidney is grossly discernable
F (end stage kidney looks the same regardless of etiology)
Histologic properties of end stage kidneys (3)
Fibrosis with lymphocytes and plasma cells
Glomerulosclerosis
Hyaline casts
Causes of end stage kidney (5)
Glomerular disease Tubular disease Vascular disease Interstitial nephritis Pyelonephritis
T/F: Large amounts of protein in the urine indicates glomerular disease
T
Glucosuria can be an indicator for ___ and can lead to ___
Diabetes mellitus
Emphysematous cystitis
Define uremia
Rapid and progressive increase in serum urea, creatinine, and phosphate AND a polysystemic toxic syndrome due to acute renal injury
T/F: Pyelonephritis is an important cause of uremia in horses
F (dogs and cats)
In dogs and cats, mineralization of the midzonal area of the gastric mucosa and necrosis of vessels are signs of ___
Uremic gastropathy
In what area in cows and horses will one find lesions similar to uremic gastropathy?
Colon
What is a common presenting clinical sign of uremia?
Vomition (may be able to smell ammonia on breath)
Four locations of mineralization in cases of uremia
Thoracic pleura (frosting)
Epicardium
Atrial endocardium
Alveolar walls in the lungs
What occurs in instances of metastatic mineralization?
Excess calcium and phosphorus circulating in the blood combine and deposit in tissues throughout the body
What occurs in instances of dystrophic mineralization?
Tissues are damaged by uremic toxins, undergo necrosis, and mineralize
Phosphorus inhibits the enzyme that activates vitamin D, which in turn helps animals absorb calcium; this condition is called ___
Secondary hypoparathyroidism
Decreased serum calcium (hypocalcemia) leads to the production of PTH, leading to bone resorption and ___
Fibrous osteodystrophy (with enlarged parathyroid glands)
Describe fibrous osteodystrophy histologically
Resorption of bone by osteoclasts with replacement by fibrous tissue
Why are renal infarcts common? (2)
Anastamoses
Primary function of the kidney is blood filtration
Components of the glomerulus (3)
Endothelial lined capillaries
Epithelial cells
Mesangial cells and mesangial matrix
Important components of the filtration barrier (3); they filter based on size of the particle and charge
Fenestrations in the endothelium
Basement membrane
Podocytes (epithelium)
Functions of mesangial cells (4)
Contract to alter capillary perfusion
Phagocytosis
Make collagen
Produce cytokines
The hallmark of glomerular disease is ___
Proteinuria
A normal protein:creatinine ratio is ___
A protein:creatinine ratio of 1-3 indicates ___
Tubular disease
A protein:creatinine ratio of >5 indicates ___
Glomerular disease
Sequelae of glomerular disease (5)
Protein losing nephropathy Nephrotic syndrome Renal failure Procoagulant state Pulmonary thrombosis and edema (if severe)
Components of nephrotic syndrome (4)
Proteinuria
Hypoproteinemia
Edema
Hypercholesterolemia
T/F: Glomerular disease is discernible based on gross lesions
F
Ways glomerular disease can be seen grossly (3)
Pinpoint red dots in the cortex Pinpoint white/tan cortical dots Pitted appearance (tubulointerstitial nephritis can look this way, too)
Types of glomerular disease (5)
Exudative glomerulitis Membranous glomerulonephritis Proliferative glomerulonephritis Membranoproliferative glomerulitis Amyloidosis
Actinobacillus equuli in horses typically results in exudative ___
Glomerulitis
T/F: Glomerulitis is inflammation affecting ONLY the glomeruli
T
___ refers to an immune mediated group of diseases that affect the glomerulus
Glomerulonephritis
In membranous glomerulonephritis, thickening of the ___ occurs
Basement membrane
In ___ glomerulonephritis, there is an increase in the number of mesangial cells and matrix
Proliferative
___ is when the glomerulus is shrunken and hyalinized, leaving only fibrosis and increased mesangial matrix
Glomerulosclerosis
Membranous glomerulonephritis, membranoproliferative glomerulonephritis, and proliferative glomerulonephritis are all caused by ___ mediated glomerular disease
Immune complex
How do immune complexes get into the glomerulus? (2)
Preformed complexes become trapped
Antibodies complex with an antigen already present in the glomerulus
What is the mechanism of Preformed antibody deposition?
Complexes call in N0, N0 release enzymes and free radicals, BM and podocyte foot processes are damaged, protein escapes
Type of reaction observed in glomerulonephritis depends on ___
Where immune deposits are located
Diseases in dogs that can lead to immune complex glomerulonephritis (11)
Infectious canine hepatitis Pyometra Pyoderma Prostatitis Lyme disease Heartworm disease Systemic lupus erythematousus Polyarteritis Autoimmune hemolytic anemia Hereditary C3 deficiency Neoplasia
Diseases in cats that can lead to immune complex glomerulonephritis (5)
Feline leukemia virus Feline infectious peritonitis virus Feline immunodeficiency virus Neoplasia Progressive membranous glomerulonephritis (idiopathic)
Diseases in horses that can lead to immune complex glomerulonephritis (2)
Equine infectious anemia
Streptococcus spp. infections
What is an important tool in visualizing immune complexes?
TEM; one can see effacement of the podocyte foot processes
What is amyloid?
A protein that can be deposited extracellularly in tissues throughout the body that can lead to dysfunction of an organ dt accumulation
How do amyloid laden organs appear grossly? Histologically?
Enlarged, pale, and waxy
Eosinophilic, homogenous, hyaline substance filled
What is the ideal stain for detectin amyloid?
Congo red
Where in the kidney can amyloid be deposited?
Glomerulus
Medullary and papillary interstitium
The hallmark of glomerular disease is ___
Proteinuria
T/F: Proteinuria is appreciated in interstitial deposition of amyloid
F; amyloid in the interstitium is a breed related disease and does not lead to glomerular disease
Name of the protein in the ascending loop and first portion of distal tubule that helps prevent water loss to the interstitium
Tamm Horsfall
When protein is lost through the glomeruli, Tamm Horsfall protein ___
Precipitates to form hyaline casts
Most important cause of acute renal failure
Acute tubular necrosis
In acute renal failure, one will appreciate ___ or ___ (pertaining to urine)
Oliguria
Anuria
Causes of oliguria and anuria in acute renal failure (2)
Tubular ultrafiltrate leaks back into the interstitium (less excretion)
Necrotic tubular epithelial cells plug up tubular lumens, leading to obstruction
Hyaline casts are an indicator of ___ leakage
Protein
Granular casts are an indicator of ___ necrosis
Tubular
What are granular casts made of?
Sloughed epithelial cells stuck together with Tamm Horsfall protein or serum
T/F: toxic damage to renal tubules leads to necrosis of renal tubular epithelium and basement membrane
F; basement membrane remains intact
T/F: ischemia of renal tubules leads to necrosis of renal tubular epithelium and basement membrane
T
T/F: toxic damage to the renal tubules is reversible
T; the basement membrane is still intact
In irreversible damage to the kidney, renal tubules are replaced by ___
Fibrosis
Toxic and ischemic damage is most severe in the ___
Proximal tubules (they are very metabolically active)
Why are kidneys so susceptible to toxic damage?
They receive a high amount of cardiac output and can concentrate toxins
Plants that cause tubular damage (8)
Easter, tiger, and other lilies (cats) Daylilies (cats) Oak leaves and acorns (herbivores) Pigweed (herbivores) Oxalate plants (rhubarb, sorrel, greasewood) Red maple leaves (hemolysis) Onions (hemolysis) Raisins and grapes (dogs)
Therapeutic drugs that can cause tubular damage (3 listed)
Doxorubicin
Aminoglycosides
Cisplatin
Etc.
What is the mechanism for ethylene glycol toxicosis?
Serum hyperosmolality and metabolic acidosis -> metabolization by the liver to glycolate and oxalate -> oxalate precipitates with calcium -> Calcium oxalate monohydrate and dihydrate crystals -> blockage of tubules and tubular epithelial damage -> anuria, renal azotemia -> renal failure; similar mechanism to melamine/cyanuric acid toxicosis
Causes of renal ischemia (3)
Lack of perfusion (dehydration/hypovolemia/shock)
Severe anemia
Vascular obstruction
Nephrotoxic pigments (2)
Hemoglobin
Myoglobin
How to distinguish hemoglobinuria, myoglobinuria, and hemorrhage
Hemorrhage will clear when centrifuged, as RBCs are intact, hemoglobin and myoglobin will not
If plasma is clear, it is myoglobin
If plasma is red, it is hemoglobin
___ causes the kidney to have dark red streaks or look blue-black diffusely; microscopically, we can see red-orange or red-brown casts within tubular lumens
Pigmentary nephrosis
Hemolytic diseases leading to pigmentary nephrosis (7)
Incompatible blood transfusions Neonatal isoerythrolysis Chronic copper toxicity in sheep Leptospirosis in cattle Babesia in cattle and dogs Red maple leaf toxicosis in horses Autoimmune hemolytic anemia in dogs
Myoglobin releasing diseases leading to pigmentary nephrosis (2)
Capture myopathy
Azoturia in horses (Monday morning disease)
This lesion is observed grossly as a tan or brown color and is often seen as an incidental lesion in horses with NSAID toxicosis
Renal papillary necrosis
What is the mechanism of renal papillary necrosis?
NSAIDS inhibit COX 1 and COX 2 -> prostacyclin vasodilator inhibition -> renal vasculature vasoconstriction -> renal papillary ischemia -> renal papillary necrosis
Nephritis found just in the glomeruli is called ___ or ___
Embolic nephritis
Purulent glomerulitis
Inflammation of the kidney that involves the tubules is called ___
Tubulointerstitial nephritis
Inflammation that involves the renal pelvis is called ___
Pyelonephritis
This type of nephritis appears as white, pinpoint spots in the renal cortex
Embolic nephritis
Bacteria that are associated with embolic nephritis (3)
Actinobacillus equuli in foals
Erysipelothrix rhusiopathiae in pigs
Trueperella pyogenes in adult cows
T/F: Causes of tubulointerstitial nephritis are typically infectious
T
Bacterial causes of tubulointerstitial nephritis (3)
Leptospira interrogans
E. coli (white spotted kidney in calves)
Salmonella spp.
Viral causes of tubulointerstitial nephritis (5)
FIP Malignant catarrhal fever virus Canine herpes virus Infectious canine hepatitis virus Equine viral arteritis
Fungal causes of tubulointerstitial nephritis (5)
Aspergillus spp. Prototheca spp. Cryptococcus neoformans Candida albicans Histoplasma capsulatum
Parasitic causes of tubulointerstitial nephritis (5)
Toxocara canis larvae Toxoplasma gondii Micronema deletrix Stephenarus dentatus Encephalitozoan cuniculi
Pathogenesis of canine leptospirosis
Leptospiremia -> localization to renal interstitial capillaries -> migration to renal tubules -> migration to lumen and association with epithelial microvilli -> necrosis and degeneration of tubules -> N0 infiltration -> lymphocytes and plasma cells invade interstitium
Renal lesion of little clinical significance in calves caused by E. coli
White spotted kidney
Renal lesion that usually results from ascending UTI
Pyelonephritis
Causes of urinary stasis leading to pyelonephritis (3)
Pregnancy
Urolithiasis
Prostatic hyperplasia
What is vesicoureteral reflex?
Retrograde flow of urine from the bladder into the ureters (can occur with micturation or manual expression of the bladder); puppies are predisposed
What does pyelonephritis look like grossly?
Necrosis and hemorrhage of the renal crest and medulla; if chronic, fibrosis originating from the renal pelvis radiating into the cortex
Bacteria that cause pyelonephritis (5)
E. coli Staph Enterobacter Proteus Pseudomonas
Important cause of bovine pyelonephritis
Corynebacterium renale
Loss of nephrons (or an entire kidney) leads to ___
Compensatory hypertrophy
These conditions cause small, pitted kidneys in young animals (4)
Hypoplastic kidneys (rare)
Progressive juvenile nephropathy
Fibrosis
Renal dysplasia
T/F: Singular cysts are a significant renal finding
F
What breeds are predisposed to polycystic kidneys? (2)
Cairn terriers
Persian cats
This renal lesion looks like “Swiss cheese.”
Polycystic kidney
T/F: Single renal cysts can be congenital or acquired
T
T/F: Primary renal tumors are common in domestic animals
F (very rare)
Most common primary renal tumor and species it affects most
Renal carcinoma
Older dog
T/F: Metastatic lymphoma in cats and cattle often involves the kidney
T
What feline illness results in lesions that appear similar to renal lymphoma?
Dry form of feline infectious peritonitis
Primary epithelial renal tumors (4)
Renal adenoma
Renal adenocarcinoma
Embryonal nephroma (nephroblastoma)
Transitional cell carcinoma
Primary mesenchymal renal tumors (4)
Fibroma
Fibrosarcoma
Renal interstitial cell tumors
Hemangiosarcoma
These bilateral multifocal renal tumors are hereditary in German Shepherd dogs and is associated with nodular dermatofibrosis
Renal cystadenocarcinoma
T/F: Nephroblastomas are typically bilateral
F (unilateral); they can metastasize though
T/F: Urinary calculi can be found ANYWHERE along the urinary tract
T
The initial step in forming a urolith is a ___
Nidus (exfoliated cells, precipitated crystalloid, bacteria, etc.)
Things that predispose to renal calculi (6)
Renal papillary necrosis Cystitis Liver failure Dehydration Diet Urine pH
Precipitation of uric acid in the renal medulla and papilla - grossly seen as white streaks in the papillae - is seen in ___
Dehydrated piglets
What species has an inherited problem with metabolism of uric acid, leading to calculi?
Dalmations
Dogs with portosystemic shunts often have high levels of circulating ammonia, leading to formation of ___
Ammonium biurate crystals
What is the name of the common condition that causes obstruction in male cats?
Feline lower urinary tract disease
Bladder rupture will lead to ___
Azotemia
Compressive force during parturition can lead to ___ in male foals
Bladder rupture
Obstruction of a ureter can cause backup of urine, parenchymal atrophy, and dilation of the renal pelvis; this is called ___
Hydronephrosis
Predisposing factors to bacterial cystitis (4)
Female anatomy
Stagnant urine
Mucosal trauma
Glucose in the urine
Glucose in the urine can lead to ___ cystitis
Emphysematous
___ grossly appears as many white, raised, mucosal nodules surrounded by a red rim
Follicular cystitis
These proliferations from the bladder mucosa are sometimes confused with transitional cell carcinoma
Polypoid cystitis
Chemical cystitis can occur in horses due to ingestion of cantharidin from ___
Blister beetle ingestion
Most common bladder malformation in which the apex of the bladder and the umbilicus is still open
Patent urachus
Animals with ectopic ureters are more susceptible to ___
Pyelonephritis
Bladder diverticula predisose to cystitis and calculi because of ___
Urine stasis
Most common bladder tumor
Transitional cell carcinoma (usually in the trigone)
Epithelial urinary bladder tumors (5)
Transitional cell carcinoma Transitional cell papilloma Squamous cell carcinoma Adenocarcinoma Undifferentiated carcinoma
Mesenchymal urinary bladder tumors (5)
Fibroma/fibrosarcoma Leiomyoma/leiomyosarcoma Rhabdomyoma/rhabdomyosarcoma Lymphosarcoma Hemangioma/hemangiosarcoma
Cattle can develop a tumor called hemorrhagic cystitis (enzootic hematuria) from ingesting ___
Bracken fern
