Urinary Flashcards
what is acute renal failure?
abrupt and sustained decrease in GFR resulting in azotaemia and fluid/electrolyte disturbance
is acute renal failure reversible?
yes, in the early stages
what is the main cause of post-renal azotaemia in horses?
neonates with bladder rupture
what pre-renal factors can lead to acute renal azotaemia?
hypovolaemia
volume redistribution (effusions…)
decreased cardiac output
altered vascular resistance (sepsis…)
what is the main renal factor that causes acute renal failure?
acute tubular necrosis secondary to ischaemia or nephrotoxin exposure
what are some possible nephrotoxins?
antibiotics - ahminoglycosides, tetracyclines…
endogenous - haemoglobin, myoglobin…
others - NSAIDs, heavy metals…
what commonly exacerbates the effect of nephrotoxic drugs?
dehydration
what should be monitored in horses being given potentially nephrotoxic drugs?
serum creatinine
what is the most nephrotoxic aminoglycoside?
neomycin
what part of the kidney are aminoglycosides toxic to?
proximal tubular epithelial cells (reabsorbed and accumulates in these which interferes with function)
what can possible be done to reduce the nephrotoxicity of aminoglycosides before they are administered?
treat with calcium
what causes NSAIDs to be nephrotoxic?
medullary crest and papillary necrosis
sloughing of tubular epithelial cells
how can acute renal failure be differentiated from pre-renal azotaemia?
pre-renal azotaemia should be rapidly reversible with fluid therapy
what electrolyte changes are seen with acute renal failure?
hyponatraemia
hypochloraemia
hypocalcaemia
hyperphosphataemia
when is hyperkalaemia seen with acute renal failure?
if the horse is oliguric
what should be done to treat acute renal failure?
IV fluids
stop nephrotoxic drugs
what fluids should be given to horses with acute renal failure?
hartmanns (maintaining twice maintenance if polyuric)
when is diuretic therapy needed for acute renal failure treatment?
if the animal is oliguric
what diuretic therapy is given to horses with acute renal failure and oliguria?
furosemide and dopamine (synergistic)
why is dopamine given as part of diuretic therapy for horses with acute renal failure and oliguria?
potent renal vasodilator acting specifically on arteriole receptors
why is chronic renal failure rare in horses?
massive reserve capacity
what are the clinical signs of chronic renal failure?
weight loss, lethargy, poor coat, PUPD
oral ulceration, gastroenteritis, halitosis
ventral oedema
how is chronic renal disease diagnosed?
persistent isosthenuria with azotaemia and clinical signs
how is chronic renal disease treated?
palliative
always need water/salt available
lower protein nutrition
decrease calcium if high in diet
what is classed as polyuria?
> 50ml/kg/day
what is classed as polydipsia?
> 100ml/kg/day
what is dysuria?
abnormal urination - pollakiuria, stranguria, haematuria, pyuria
what are some possible causes of PUPD?
renal failure
PPID
excessive salt consumption
diabetes
sepsis/endotoxaemia
iatrogenic
why does PPID cause PUPD?
hyperadrenocorticism causes increased cortisol which is a vasopressin antagonist so decreases vasopressin production/release
why does diabetes mellitus cause PUPD?
hyperglycaemia leads to glycosuria cause osmotic polyuria and hence polydipsia
what is a water deprivation test used for?
distinguish between diabetes insidious and psychogenic polydipsia
what are some contraindications for performing water deprivation tests?
if animal is azotaemic or dehydrated
how is a water deprivation test carried out?
empty bladder and get baseline body weight
deprive water of water access
measure USG, body weight and urea periodically
if USG increases >1.025 within 24 hours then they have psychogenic polydipsia
what are the 3 main causes f red/brown urine?
blood
haemoglobin
myoglobin
if you spin red/brown urine and it separates what can be diagnosed?
haematuria
if you spin red/brown urine and it doesn’t separate what can be diagnosed?
haemoglobinuria
myoglobinuria
how can red/brown urine due to myoglobin and haemoglobin be differentiated?
myoglobin will have increased creatine kinase and AST on serum biochemistry
what are some causes of rhabdomyolysis?
sporadic/recurrent exertional
polysaccharide storage myopathy
atypical myopathy
post-anaesthetic myositis
what are some possible causes of haemolysis?
immune mediated haemolytic anaemia
neonatal isoerythrolysis
infectious - babes, EIA
if haematuria occurs throughout urination where can it be localised to?
kidney, ureter or bladder
if haematuria occurs at the start of urination where can ut be localised to?
distal urethra
if haematuria occurs at the end of urination where can it be localised to?
proximal urethra and bladder neck
