Urinary medicine (Yr4) Flashcards
what causes pre-renal acute renal failure?
haemodynamic cause…
hypovolaemia, volume redistribution (effusions), decreased cardiac output, altered vascular resistance (endotoxaemia)
what cause post-renal acute renal failure?
uncommon… only really seen with neonates that rupture there bladder as blockages are uncommon
what are the renal causes of acute renal failure?
ischaemia or nephrotoxin exposure (less commonly glomerulonephritis)
what are some nephrotoxic substances?
antibiotics - aminoglycosides, tetracyclines
endogenous substances - haemoglobin, myoglobin
NSAIDs, heavy metals…
what should be monitored in horses on nephrotoxic drugs?
serum creatinine
what is the most nephrotoxic aminoglycoside?
neomycin
where do aminoglycosides accumulate?
proximal tubular cells (they are freely filtered at the glomerulus then reabsorbed by proximal tubular cells)
why are aminoglycosides (such as gentamicin) only given once daily?
reabsorption in the kidneys is time rather than dose dependant, so less toxic to give one large dose
what can you pre-treat horses with before giving gentamicin (aminoglycosides) to reduce the nephrotoxicity?
calcium
what will be a significant finding on urinalysis if there is pre-renal azotaemia?
maximally concentrated urine (>1.035)
how is acute renal failure treated?
IV fluids (Hartmans)
diuretics (furosemide)
stop nephrotoxic drugs
what fluid rate would you put a horse with acute renal failure on?
twice maintenance (60ml/kg/hr)
what diuretics can be used for treating acute renal failure?
furosemide
dopamine
what are the main causes of chronic renal failure?
glomerular disease
interstitial nephritis (from tubular necrosis)
renal neoplasia
amyloidosis
what clinical signs can be seen with chronic renal failure?
chronic weight loss
lethargy, PUPD, poor coat, poor performance
halitosis, oral ulceration
(possible ventral oedema but this is inconsistent)
how is chronic renal failure diagnosed?
persistent isosthenuria (1.008-1.014)
mild anaemia and hypoalbuminaemia
electrolyte abnormalities (hypercalcaemia, hyponatraemia…)
how can chronic renal failure be treated?
one;y palliative…
ensure water and salt available
lower protein (manage BUN)
decrease calcium
what is a good prognostic indicator for chronic renal failure?
creatinine (higher creatinine indicates a shorter survival time)
what is polyuria defined as?
urine output exceeding 50ml/kg/day
what is polydipsia defined as?
fluid intake exceeding 100ml/kg.day
what is dysuria?
abnormal urination
what are some possible causes of PUPD?
renal failure
PPID
psychogenic polydipsia
excessive salt consumption
diabetes
sepsis/endotoxaemia
iatrogenic
what age horses does PPID effect?
older
why does PPID cause PUPD?
PPID causes increased ACTH, cortisol antagonism of vasopressin on the collecting ducts meaning less reabsorption of water
how common is psychogenic PUPD seen in horses?
one of the most common causes (boredom, change environment, diet….)
why does diabetes insipidus cause PUPD?
there is a decreased volume of vasopressin, and also decreased sensitivity of the renal collecting ducts to vasopressin
why does diabetes mellitus cause PUPD?
hyperglycaemia leads to glycosuria causing an osmotic polyuria (and hence polydipsia)
what is the value for hyposthenuria in horses?
<1.007
what are the top difference if a horse has PUPD with hyposthenuria but no azotaemia?
psychogenic polydipsia
diabetes insipidus
what test can be done to distinguish between diets insipidus and psychogenic polydipsia?
water deprivation test
how can the water deprivation test differentiate between diabetes insipidus and psychogenic polydipsia?
if USG increases to >1.025 in less than 24 hours it is psychogenic polydipsia
if it stays hyposehtnuric its diabetes insipidus
how is a water deprivation test carried out?
empty bladder and get a baseline bodyweight
deprive horse of water access and measure USG, bodyweight and urea periodically
(stop if horse becomes azotaemic, dehydrated or loses 5% bodyweight)
what is a modified version of the water deprivation test?
medullary washout
how is the medullary washout done?
restrict water to 40ml/kg/day for 3-4 days
USG >1.025 at the end of this indicates psychogenic polydipsia
what are the two types of diabetes insipidus?
neurologenic
nephrogenic
how can you differentiate between neurogenic and nephrogenic?
neurogenic… USG increases >1.020 following ADH or vasopressin administration
nephrogenic… no change ion USG following ADH or vasopressin
how can you differentiate between haematuria and haemoglobinuria?
centrifuge the samples, haematuria will separate haemoglobin/myoglobinuria won’t
what is the pathogenesis of why myoglobinuria occurs?
muscle cells rupture releasing myoglobin (rhabdomyolysis)
what can cause myoglobinuria?
sporadic/recurrent exertional rhabdomyolysis
polysaccharide storage myopathy
atypical myopathy
post-anaesthetic myositis
how is myoglobinuria diagnosed?
clinical signs (urinalysis)
increased creatinine kinase
what are some causes of haemoglobinuria?
immune mediated haemolytic anaemia
neonatal isoerythrolysis
infectious causes (babesia, EIA…)
what can cause haematuria?
urinary tract infection
urolithiasis
neoplasia
if there is haematuria throughout the entire urination, where can you localise the lesion to?
kidney
ureters
bladder
if there is haematuria at the start of urination, where can you localise the lesion to?
distal urethra
if there is haematuria at the end of urination, where can you localise the problem to?
proximal urethra and bladder neck
what are some causes of haematuria?
urinary tract infections (pyelonephritis, cystitis)
urolithiasis
what horses are predisposed to urolithiasis?
males (shorter urethra)
older horses
what are some predisposing factors to urolithiasis?
urine retention, UTI, genetics
alkaline urine
what is sabulous cystitis?
crystalloid sediment build up in the ventral bladder secondary to bladder paralysis or emptying problems
what is the prognosis for sabulous cystitis?
poor (needs regular bladder emptying and secondary UTI control)
