Pathology of neph/uro system Flashcards
What is different about cat kidneys (gross pathology)
Normally pale due to fat content of the tubular epithelia
What is different about dog kidneys (gross pathology)
Have pale streaks in the inner dortex on cut surface - fat in collecting ducts
What is different about rabbit urine?
Excrete excess calcium in their urine in the form of calcium carbonate (cloudy urine)
What is different about bovine kidneys (gross pathology)
No renal pelvis
What is different about equine kidneys (gross pathology)
Renal pelvis has mucus glands and may be cloudy due to calcium carbonate crystals
Which species have multi-lobar kidneys?
Cattle
Otters
Whales
Size of kidneys in various pathologies
Acute inflammation often causes enlargement
Chronic inflammation causes scarring (reduction in size)
Renal blood supply
Renal -> interlobar -> arcuate -> interlobular -> afferent artery -> efferent artery
Homeostatic functions of the kidney
Excretion of nitrogenous waste products, e.g. urea, creatinine
Conservation of water (loop of Henle, ADH)
Acid-base regulation (bicarbonate)
Electrolyte regulation (potassium, sodium, phosphate)
Endocrine roles (erythropoietin, renin, prostaglandins, Vitamin D)
When will renal failure occur?
Inadequate perfusion (pre-renal) e.g. dehydration, shock, cardiac failure
Inadequate processing (renal) e.g. infections, nephrotoxicity, neoplasia, fibrosis
Inadequate discharge (post-renal) e.g. obstruction, urinary bladder rupture or dysfunction
Four stages of progression to uraemia
Diminished renal reserve - asymptomatic
Renal insufficiency - azotaemic
Renal failure - uraemia
End stage renal disease - terminal stages
What is optimal renal function reliant on?
Adequate perfusion
Sufficient functional nephrons
Normal elimination of urine
GFR equation
GFR = (BP - OP) -IRP
BP= blood pressure
OP = osmostic pressure
IRP = intra-renal pressure
What effect does increased plasma albumin concentration have on GFR?
Decreases GFR as it increases osmotic pressure
Azotaemia
Elevated blood biochemical parameters
Increased concentrations of urea and creatinine
○ Pre-renal azotaemia: hypoperfusion
○ Post-renal azotaemia: urinary obstruction
Uraemia
Clincial signs and pathology associated with azotaemia in animals with renal dysfunction (chronic end-stage renal disease)
Multisystemic toxicosis
Clinical signs of acute renal failure
Oliguria or anuria
Vomiting
Anorexia
Clinical signs of chronic renal failure
polydipsia and polyuria, as well as the clinical signs associated with uraemia.
Pathology of animals that have died of uraemia
Necrosis of oral mucosa (ammonia excretion)
Haemorrhagic erosion of GI mucosa (haematemesis, melaena)
Necrosis of left atrial endocardium (necrotising endocarditis)
Necrosis and dystrophy and metastatic calcification of intercostal muscles & pleura
Uraemic pneumonitis
Uraemic pneumonitis
Firm glassy cut surface
Pulmonary oedema
Mineralisation of alveolar walls
Degeneration of blood vessels
Dystrophic mineralisation
Occurs in areas of necrosis
Dead and dying cells can no longer regulate cytoplasmic calcium influx, and calcium accumulates in the mitochondria
Metastatic mineralisation
Occurs in normal tissue
Secondary to hypercalcaemia
Calcium ions precipitate on organelles, particularly mitochondria
Juxtaglomerular cells
Modified smooth muscle
Renin secretion in response to altered renal blood flow & sympathetic nerve activity
Macula densa
Specialised distal tubular epithelial cells
Renin secretion in response to altered [Na+]
Extraglomerular mesangial cells
Function unknown
Sequelae of reduced renal blood flow
Renin release from juxtaglomerular apparatus
-> aldosterone release from adrenals
-> Na retention in convoluted tubules
-> water retention
-> increased blood volume
-> increased blood pressure
-> renin acts on circulating angiotensinogen
-> angiotensin
-> increased peripheral resistance in small blood vessels
-> increased blood pressure
Pathological effects of sustained hypertension
Hypertrophy of the left ventricular myocardium
Damage to small blood vessels
Results of hypertension on the kidney
Results in nephrosclerosis with obliteration of glomeruli and atrophy and replacement fibrosis of the collecting tubules served by the efferent glomerular arteriole.
What is hypertensive retinopathy usually associated with?
Chronic renal failure
At least 60% of dogs with CRF are hypertensive
Fibrous osteodystrophy
A non-renal lesion of renal failure
Extensive bone resorption accompanied by proliferation of fibrous tissue & poorly mineralised, immature bone.
Due to persistent elevation of plasma PTH - primary or secondary hyperparathyroidism e.g. chronic renal failure
Can bend the mandible because it is so rubbery and flexible
