Pathology of neph/uro system

Question 1

What is different about cat kidneys (gross pathology)

Answer 1

Normally pale due to fat content of the tubular epithelia

Question 2

What is different about dog kidneys (gross pathology)

Answer 2

Have pale streaks in the inner dortex on cut surface - fat in collecting ducts

Question 3

What is different about rabbit urine?

Answer 3

Excrete excess calcium in their urine in the form of calcium carbonate (cloudy urine)

Question 4

What is different about bovine kidneys (gross pathology)

Answer 4

No renal pelvis

Question 5

What is different about equine kidneys (gross pathology)

Answer 5

Renal pelvis has mucus glands and may be cloudy due to calcium carbonate crystals

Question 6

Which species have multi-lobar kidneys?

Answer 6

Cattle
Otters
Whales

Question 7

Size of kidneys in various pathologies

Answer 7

Acute inflammation often causes enlargement

Chronic inflammation causes scarring (reduction in size)

Question 8

Renal blood supply

Answer 8

Renal -> interlobar -> arcuate -> interlobular -> afferent artery -> efferent artery

Question 9

Homeostatic functions of the kidney

Answer 9

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)

Question 10

When will renal failure occur?

Answer 10

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

Question 11

Four stages of progression to uraemia

Answer 11

Diminished renal reserve - asymptomatic

Renal insufficiency - azotaemic

Renal failure - uraemia

End stage renal disease - terminal stages

Question 12

What is optimal renal function reliant on?

Answer 12

Adequate perfusion

Sufficient functional nephrons

Normal elimination of urine

Question 13

GFR equation

Answer 13

GFR = (BP - OP) -IRP

BP= blood pressure
OP = osmostic pressure
IRP = intra-renal pressure

Question 14

What effect does increased plasma albumin concentration have on GFR?

Answer 14

Decreases GFR as it increases osmotic pressure

Question 15

Azotaemia

Answer 15

Elevated blood biochemical parameters

Increased concentrations of urea and creatinine
○ Pre-renal azotaemia: hypoperfusion
○ Post-renal azotaemia: urinary obstruction

Question 16

Uraemia

Answer 16

Clincial signs and pathology associated with azotaemia in animals with renal dysfunction (chronic end-stage renal disease)

Multisystemic toxicosis

Question 17

Clinical signs of acute renal failure

Answer 17

Oliguria or anuria

Vomiting

Anorexia

Question 18

Clinical signs of chronic renal failure

Answer 18

polydipsia and polyuria, as well as the clinical signs associated with uraemia.

Question 19

Pathology of animals that have died of uraemia

Answer 19

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

Question 20

Uraemic pneumonitis

Answer 20

Firm glassy cut surface

Pulmonary oedema

Mineralisation of alveolar walls

Degeneration of blood vessels

Question 21

Dystrophic mineralisation

Answer 21

Occurs in areas of necrosis

Dead and dying cells can no longer regulate cytoplasmic calcium influx, and calcium accumulates in the mitochondria

Question 22

Metastatic mineralisation

Answer 22

Occurs in normal tissue

Secondary to hypercalcaemia

Calcium ions precipitate on organelles, particularly mitochondria

Question 23

Juxtaglomerular cells

Answer 23

Modified smooth muscle

Renin secretion in response to altered renal blood flow & sympathetic nerve activity

Question 24

Macula densa

Answer 24

Specialised distal tubular epithelial cells

Renin secretion in response to altered [Na+]

Question 25

Extraglomerular mesangial cells

Answer 25

Function unknown

Question 26

Sequelae of reduced renal blood flow

Answer 26

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

Question 27

Pathological effects of sustained hypertension

Answer 27

Hypertrophy of the left ventricular myocardium Damage to small blood vessels

Question 28

Results of hypertension on the kidney

Answer 28

Results in nephrosclerosis with obliteration of glomeruli and atrophy and replacement fibrosis of the collecting tubules served by the efferent glomerular arteriole.

Question 29

What is hypertensive retinopathy usually associated with?

Answer 29

Chronic renal failure At least 60% of dogs with CRF are hypertensive

Question 30

Fibrous osteodystrophy

Answer 30

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