Pathology of kidneys & lower UTI Flashcards
What are the 2 pathways an infection of the kidney can follow?
Haematogenous (descending)
Urinary (ascending)
Give examples of causes of infectious diseases of the kidney
Viral: Canine herpesvirus 1, Canine Adenovirus 1, Ovine Herpesvirus 2
Bacterial: Leptospira interrogans, Actinobacillus equuli, Escherichia coli, Corynebacterium renale
Parasitic: Toxocara canis, Halicephalobus gingivalis, Encephalitozoon cuniculi, Leishmania spp
What are the 2 types of nephritis?
Non-suppurative tubulointerstitial nephritis
- Lympho-histiocytic inflammation
Suppurative interstitial nephritis
- Embolic nephritis (Haematogenous)
- Pyelonephritis (Ascending) (Inflammation in both pelvis & renal parenchyma)
What are the main causes of non-suppurative tubulointerstitial nephritis?
Leptospira interrogans, Escherichia coli, Maedi-Visna virus, FIP virus, Canine herpesvirus 1, Canine Adenovirus 1, Ovine Herpesvirus 2, Encephalitozoon cuniculi
How do kidneys appear in acute and chronic non-suppurative tubulointerstitial nephritis?
Acute nephritis:
Swollen, pale tan kidneys.
Random gray mottling on capsular surface.
Chronic nephritis:
Fibrotic kidneys
What are the histological features of acute and chronic non-suppurative tubulointerstitial nephritis?
Acute:
Interstitial oedema, mononuclear infiltration, tubular degeneration & necrosis
Chronic:
Mononuclear cell infiltration (lymphocytes, plasma cells, histiocytes).
Interstitial fibrosis & tubular atrophy
What is suppurative embolic nephritis and what causes it?
Septic emboli lodge in glomerular/peritubular capillaries, leading to microabscesses
- larger emboli lodge in arteries & cause septic infarcts
Common causes:
Actinobacillus equuli (foals)
Erysipelothrix rhusiopathiae
Trueperella pyogenes
What are the main causes of pyelonephritis?
Endogenous bacteria of bowel & skin:
- Escherichia coli, Staphylococci, Streptococci, Enterobacter, Proteus, Pseudomonas
Specific pathogens of urinary tract:
- Corynebacterium renale (cattle)
- Actinobaculum suis (swine)
How does pyelonephritis develop?
Ascending infection → Bacteria ascend from lower urinary tract due to vesicoureteral reflux
Establishes infection in renal pelvis & spreads into medulla
What are the gross lesions of pyelonephritis?
Pelvic mucosa: Inflamed, thickened, exudate-coated
Papillae: Ulcerated, necrotic
Renal medulla: Irregular red or grey radial streaks extending from pelvis
What are the microscopic features of pyelonephritis?
Transitional epithelium: Necrotic, sloughed, covered in debris, fibrin, neutrophils & bacterial colonies
Medullary tubules: Dilated, filled with neutrophils & bacterial colonies
Chronic lesions: Severe fibrosis
What are the main pathways of lower urinary tract infections?
Descending (originating from nephritis or pyelonephritis)
Ascending (originating from urethra)
What are the 3 most common lower urinary tract infections?
Ureteritis (usually secondary to cystitis)
Cystitis (Most common, affects the bladder)
Urethritis (Often due to urinary obstruction or urethral plugs)
What are the common bacterial causes of cystitis?
Escherichia coli, Proteus vulgaris, streptococci, staphylococci, enterococci
Bacteria ascend from urethra, usually from rectal or cutaneous flora
What are the predisposing factors for cyctitis?
Urine stagnation (obstruction, incomplete bladder emptying)
Urothelial trauma (uroliths, catheterization, vaginoscopy)
Urinary incontinence, diabetes mellitus, antibiotic/corticosteroid use, hyperoestrogenism, immunodepression
Gender (shorter urethra in females)
Comorbidities (e.g., pyometra, prostatitis)
What are the defense mechanisms of the bladder against infection?
Urothelial barrier
Urine pH and osmolality
IgA, IgG, Tamm-Horsfall mucoprotein
Shedding of infected urothelial cells
What are the gross pathological forms of cystitis?
Acute:
Haemorrhagic, catarrhal, fibrinopurulent, necrotizing, ulcerative
Chronic:
Diffuse, follicular, polypoid (often associated with chronic infection or urolithiasis).
Emphysematous (associated with glycosuria)
What are the histological features of acute ulcerative cystitis?
Ulceration, inflammatory infiltrate and hyperaemia
What are the histological features of chronic follicular cystitis?
Aggregate of proliferating lymphocytes designing a lymphoid follicle.
What are the histological features of chronic polypoid cystitis
polyp (villus-like projection) covered by epithelium over core of proliferated connective tissue densely infiltrated by inflammatory cells, haemorrhage & hemosiderin
Note epithelial down-growth that appears round in cross section
What are some common non-infectious causes of cystitis in different species
What are the main categories of urinary tract pathology?
Tubulointerstitial nephritis
Neoplasia
Lesions secondary to renal failure
What is tubulointerstitial nephritis
Diseases involving primarily the interstitium and tubules
What are the main types of tubulointerstitial nephritis?
Non-suppurative (haematogenous or ascending)
Embolic suppurative (haematogenous, bacterial septic emboli)
Pyelonephritis (mostly ascending infection)
What is embolic suppurative nephritis?
Caused by bacterial emboli in bloodstream
Leads to multiple small abscesses or larger abscess formation
Fill in the table with most common agents causing embolic suppurative nephritis in different species
Describe the gross & histological appearance of embolic suppurative nephritis
Gross:
- disseminated lesion on surface of kidney
- when we section kidney, see slightly bulging microabscesses
Why?
- Because histologically, there are bacteria stuck in glomerulus which trigger inflammatory response dominated by
fibrin oxidation & neutrophilic influx
What are the risk factors of pyelonephritis
Female gender (short urethras, urethral trauma during pregnancy or parturition)
Urine stasis/obstruction/urolithiasis
Others: Diabetes, hyperestrogenism, congenital malformations (ureteral ectopia, urinary bladder aplasia)
What are the most common renal tumors?
Renal carcinoma
- Common in dogs, cattle & horses
- highly malignant with common metastasis
Nephroblastoma
- common in pigs & chickens
Lymphoma
- Common in cattle and cats
- metastatic
Describe the gross & histological appearance of renal carcinomas
Gross:
- kidney is effaced & infiltrated by multifocal, haemorrhagic & necrotic neoplastic growth, obscuring normal architecture
Histologically:
- typical epithelial growth pattern, characterized by tubular structures or anastomosing cellular arrangements
- neoplastic cells exhibit moderate mitotic activity, with nuclear pleomorphism & prominent nucleoli
- Some cells display vascular nuclei, while mid-stage mitoses are also observed
Describe the gross & histological appearance of renal lymphoma
Gross:
- multinodular masses that are bulging, well-demarcated & white with glistening, fatty-like appearance
- Generally well-defined but some margins appear blurred due to infiltrative growth
Histologically:
- dense sheets of round cells, which are tightly packed & efface normal parenchyma
- typical round-cell growth pattern
What is the most common lower urinary tract neoplasm?
Epithelial tumours like Urothelial cell carcinoma
Mostly in the urinary bladder
Uncommon overall (Dogs > Cats»_space; Other species)
What are some common systemic changes associated with chronic renal failure
Parathyroid hyperplasia
Fibrous osteodystrophy
Metastatic mineralisation (stomach, lung, pleura, kidneys)
Ulcerative & haemorrhagic gastritis & glossitis/stomatitis
Pulmonary oedema & fibrinous pericarditis
Atrial and vascular thrombosis
Anaemia
What causes these systemic changes associated with chronic renal failure
What systemic change is this
Glossitis
What systemic change is this
Metastatic mineralisation
What systemic change is this
Fibrous osteodystrophy
