What does pre-renal functional problems cause?
Compromised renal perfusion - Reduced RBF leading to Renal Ischemia
What does functional problems intrarenally cause?
Compromised kidney function
What does post-renal functional problems cause?
Obstruction of urine outflow
When does acute renal failure occur?
When over 75% of renal function is abruptly impared
What are the main signs of acute renal failure?
Azotaemia - Cardiac dysrrythmia (due to to K retention) - Muscle tremors and coma (due to phosphate retention) - Metabolic acidosis (due to failure of pH control) - Hypertension - Oliguria
What is chronic renal failure characterised by?
Prolonged signs of uraemia
Define azotemia. How is it caused?
Retention of nitrogenous metabolites - Insufficient glomerular filtration
What are the clinical signs of chronic renal disease?
Polyuria - Isosthenuria - Polydipsia - Halitosis - Dribbling - Lank coat - Weight loss
Urea in the blood
Give the progression of normal renal function to uraemia
1- Diminished renal reserve, GFR 50% of normal 2- Renal reserve, GFR 20-50%, azotaemic and polyuric 3- Renal failure, 20-25%, kidneys can't maintain homeostasis = uraemia 4- End-stage renal disease, 5%, terminal stages of uraemia
What are the systemic effects of uraemia?
Causes retention of electrolytes (esp Ca) - Plasma protein loss - Hyperphosphataemia - Secondary renal hyperparathyroidism - Reduced erythropoietin - Hypertension
How does uraemia cause Secondary renal hyperparathyroidism?
Reduced GFR - inadequate secretion of phosphate - Precipitation of ionised calcium concentration - Reduced activation of Vit D - Reduced Ca absorption - PTH stimulated - Osteoclastic bone resorption
How does uraemia cause non-renal lesions?
Endothelial degeneration and necrosis = vasculitis and secondary thrombosis Large amounts of ammonia/bacteria in saliva
What are the portals of entry for infection into the kidney?
Haematogenous - Glomerular infiltrate - Ascending ureter - Direct penetration
What are the defence mechanisms within the kidney?
Urine flow flushes out bacteria - pH of urine - basement membrane
What are the categories of renal disorders?
Glomerular - Tubular - Interstitial - Vascular system
What condition is affecting these kidneys?
What is the pathogenesis of hydronephrosis?
Obstruction of outflow tract - Increased pressure in renal pelvis - Tubules undergo necrosis and atrophy - Interstitial fibrosis - Pale radiatiing rays
What is the condition of this cows kidney? What are the gross problems?
Pyelonephritis - Renal calyces contain supprative exudate bordered by red rim of haemorrhage
What infectious agents are involved in pyelonephrotitis in cows?
E. coli - Arcanobacterium pyogens - Cornyebacterium renale
When are cows most likely to get pyelonephrititis? What other species is susceptible?
Post-partum period - Sows
What is this condition called? What are the microscopic features of this disease?
Acute tubular necrosis - Diffuse degeneration and necrosis of epithelial cells of convoluted tubules
What can cause acute tubular necrosis?
Ischaemia - Nephrotoxins - Inflammation - Certain infectious agents
What causes chronic renal failure?
This is a histological section of a cat's pancreas - What has happened and what could cause it?
Vacuolated beta cell islets consistent with hydropic degeneration - Type 2 diabetes
This is the bladder of a cat with type 2 diabetes - what has caused this?
Glycosuria in diabetes mellitus enhances bacterial growth
What is the common name for this disease? What can cause it?
Renal infarction - Blockage of artery (neoplasia, embolism), damage of vasculature (toxins)
Describe the gross appearance of this kidney
Multifocal small pale/white nectrotic foci
Describe what is in these microscopic images of the kidney with multifocal white/red lesions. What is this condition know as?
Microabscesses centered on glomeruli - Bacterial, neutrophils and necrotic debris - Suppurative glomerulitis (embolic nephritis)
What causes supprative glomerulitis?
Bacterial invasion - Haematogenous route and lodge in capillaries of glomeruli - Replicate and induce necrosis & inflammation
How can immune mediated glomreulonephritis occur?
Formation of antibodies against entrapped nonspecific antigens withing the glomerular basement membrane
What is glomerular amyloidosis commonly associated with? Why?
Chronic inflammatory disorders, systemic infectious diseases or neoplasia - Acute phase proteins cause amyloid deposits in glomeruli
How can you diagnose that there is amyloid deposition in the kidney?
Stain with congo red - Amyloid is apple green when viewed under polarised light
What is acute supprative glomerulitis also known as?
Bacterial or embolic nephritis
What is seen in the kidney during acute suppurative glomerulitis?
Formation of microabscesses throughout the cortex
What is glomerulosclerosis?
Reduction in number of functional glomeruli
What is the most common cause of tubular disease?
What is the response of tubules to injury?
Degeneration - Necrosis - Apoptosis - Cells slough into lumen forming cellular casts - Compensatory hypertrophy
Why is it detrimental if the basement membrane undergoes necrosis as well as the tubule?
Nephrons don't regenerate
Name 3 congenital disorders of renal tubular function
Primary renal glycosuria (reduced glucose reabsorption) - Fanconi syndrome (reduced protein, glucose, phosphate and amino acid reabsorption) - Cystinuria (calculus formation & obstruction in male dogs)
What is the most important cause of acute renal nacrosis? What causes it?
Acute tubular necrosis - Nephrotoxic or ischemic injury
Why can muscle damage cause acute tubular necrosis?
Myoglobinuric nephrosis released from damaged muscle cells - Amplifies effects of toxins in combination with ischemia
Give examples of toxins that can cause acute tubular necrosis
Heavy metal - Pharmaceutical agents (NSAIDs) - Fungal and plant toxins - Ethylene glycol (antifreeze) - Vitamin D - Bacterial toxins
What is the renal interstitium?
Fibrovascular stroma that surrounds the nephron
What can cause renal interstitial disease?
Ascending infection (pylonephritis) - Haematogenous (E. coli, Leptospira, Canine adenovirus) - Secondary to injury of vasculature/tubules/glomeruli
What are the responses to interstitial injury?
Oedema - Haemorrhage - Inflammation - Fibrosis
Why is any disease or damage to the renal vascular system detrimental?
Arterial blood supply to the cortex is terminal (no anastomoses) so will have a knock on effect to nephron blood supply
What is the difference between hyperaemia and congestion?
Hyperaemia is an active processs where arterial dilation causes increased blood flow (inflammatory response) - Congestion is a passive process where blood accumulates in venous system (secondary to hypovolaemic shock/cardiac insufficiency/hypostatic)
What is Virchow's triad?
Major determinants of thrombosis - Endothelial injury, Dynamics of blood flow, Hypercoagulability of blood
What is disseminated intravascular coagulation? What can cause it?
Serious manifestation of abnormal coagulation, generation of excess thrombin - Complication of any condition associated with widespread thrombin activation
Whata re the main diseases of the renal pelvis?
Hydronephrosis - Pyelonephritis - Papillary necrosis
What is the main cause of hydronephrosis?
Obstruction of urine outflow
What has occured on this photo?
What is pyelonephritis?
Bacterial infection of the renal pelvis
What has occured on this photo?