Urinary system pathology 2 Flashcards
Give 3 examples of inflammatory kidney conditions
- Glomerulonephritis
- Tubulointerstitial nephritis
- Pyelonephritis
What is glomerulonephritis?
Inflammation of glomeruli with secondary damage to other parts of the nephron
Glomerular damage produces…?
- increased permeability
- reduced perfusion of the downstream parts of the tubule
Can glomeruli compensate for damage?
They are incapable of regeneration but can hypertrophy to a limited extent
Describe the pathogenesis of glomerulonephritis
- Immune mediated
- Immune complexes deposited in glomeruli
- These cause obstruction to filtration slits
- Type III hypersensitivity reaction which damages the glomerulus
Describe the type III hypersensitivity reaction that occurs in glomerulonephritis - explain the damage caused by this reaction
- Antigen-antibody complex blocks filtration pores within the glomerulus
- They then fix complement which is attracted to the immune complex
- Neutrophils latch on and degranulate: lysosomal enzymes released from the neutrophils damage the vessel wall causing exposure of the underlying basement membrane
Following damage to the basement membrane from the type III hypersensitivity reaction, what happens to the damaged site?
Fibrin is deposited in the attempt to form a clot and stabilise the site
What are some causes of glomerulonephritis is the following species:
- dog
- cat
- pig
- cow
- infectious canine hepatitis, pyometra, neoplasia
- FeLV, FIP, neoplasia
- Classical swine fever, porcine reproductive and respiratory syndrome
- Bovine viral diarrhoea
How do the kidneys appear grossly in acute glomerulonephritis?
- swollen and reddened
- diffusely scattered over the renal cortical surface there are fine red dots of less than 1mm in diameter
How do the kidneys appear grossly in chronic glomerulonephritis?
- fibrosis and scarring
- the collagen lay down by fibroblasts contracts which leads of a pitted surface
What are 3 consequences of glomerular damage?
- increased permeability
- reduced perfusion of downstream tubules
- proteinuria
Describe post-weaning multisystemic wasting syndrome
- occurs in growing/fattening pigs
- caused by porcine circovirus 2
- necrogranulomatous hepatitis, interstitial pneumonia
Describe Porcine Dermatitis + Nephropathy Syndrome
- Caused by porcine circovirus 2
- Occurs following Post-weaning Multi-systemic Wasting Syndrome outbreaks in pig herds
How do kidneys appear in Porcine Dermatitis + Nephropathy Syndrome
Kidneys are enlarged, pale brown with petechial haemorrhages.
- systemic necrotising vasculitis of skin (over the whole body) + kidneys.
‘Multifocal to coalescing erythematous skin lesions, some progressing to dermal necrosis. Bilateral renal enlargement with multifocal cortical petechiae’
How does glomerulonephritis (e.g. Porcine Dermatitis + Nephropathy Syndrome) appear histologically?
- Intense pink staining means it is highly proteinaceous = fibrin deposited within the glomerulus
- RBCs visible in the glomerulus
- Fibroblasts within the parenchyma and inflammatory cells.
- Bowman’s space dilated by RBCs (shouldn’t be there), distorted by pink amorphous material (fibrin)
Describe the pathogenesis of tubulointerstitial nephritis
Interstitial inflammation and fibrosis results in tubular atrophy and degeneration with secondary damage to glomeruli and vessels
- Tubular damage stimulates inflammation which goes into the interstitium
=> chronic renal disease
What is the main cause of acute tubulointerstitial nephritis in dogs?
Canine leptospirosis
What is the source of infection of canine leptospirosis?
Rats
Describe how canine leptospirosis is transmitted directly and indirectly
Direct - via infected urine, bites or ingestion of infected tissues
Indirect - via exposure to contaminated water, soil, food or bedding
How do kidneys with acute tubulointerstitial nephritis appear grossly?
Swollen and reddened
How do kidneys with acute tubulointerstitial nephritis (canine leptospirosis) appear histologically?
Leptospira associate with microvilli of P/DCT => ep necrosis
Secondary interstitial inflammation with lymphocytes, plasma cells + macrophages
How does leptospirosis cause chronic tubulointerstitial nephritis?
- Leptospiras can persist in renal tubules without causing disease + excreted in urine for long periods
What is the importance of leptospirosis in cattle?
Zoonotic
What are the possible causes of suppurative interstitial nephritis?
Pyogenic organisms either haematogenously or ascending up pelvis:
- E.coli (white spot kidney in cattle)
What are the 2 causes of granulomatous interstitial nephritis?
- FIP in cats
- Mycobacteria bovis
How does FIP appear grossly and histologically?
Gross - pale yellow/tan cortex, multifocal creamy nodules in cortex and medulla, pus, increased firmness
Histological - neutrophil dominated response, macrophages, large amounts of purple stippling
What is a pyelonephritis?
Ascending LUT infection - bladder, urethra and ureters
What makes females predisposed to pyleonephritis?
Shirt, wide urethra which is more likely to get infected
What are some causes of pyelonephritis?
- Urine stasis, not passing frequently enough, retention
- Retrograde flow from the bladder back up the ureters
- Local trauma e.g. calculi
Give examples of bacterial species that can cause pyelonephritis
- E.coli
- Staphylococcus
- Streptococcus
Describe the gross appearance of a kidney with pyelonephritis
- Multifocal to coalescing areas of red/black colouration extending from the renal pelvis to the cotex
- Necrosis
Describe the histological appearance of a kidney with pyelonephritis
- purple stippling
- lots of inflammatory cells
- fibrosis
- glomerular sclerosis
Give an example of parasitic renal disease
Toxocara canis
- roundworm of dogs
- neglect
How does Toxocara canis cause renal disease?
Migration of ascarid larvae producing granulomatous nephritis – stimulate a macrophage dominated response in the kidney
