Equine kidney disease Flashcards
What pH is equine urine normally
Alkaline
What are the isothenuric, hypothenuric and hyperthenuric ranges
Hypo = <1.008
Iso = 1.008 - 1.014
Hyper = >1.014
What is GGT:creatinine ratio used for
Sensitive marker of tubular injury/dysfunction because GGT is high when there is leakage from tubular epithelium
What counts as polydipsia
> 100ml/kg/day
What is the most common cause of polydipsia in horses
Psychogenic
When do we see an increase in creatinine in blood
When 75% of kidney function is lost
What is SDMA
Endogenous arginine released into bloodstream during protein catabolism
-Not excreted in kidney failure
- Suggested to detect kidney injury earlier than creatinine but not clear
What electrolyte abnormalities are seen in AKI
Hyponatraemia and hypochloraemia are main ones
What electrolyte abnormalities are seen in CKD
Hyperkalaemia
hypercalcaemia
Hyponatraemia
Why do we see hypercalcaemia in CKD
Lack of excretion in CKD
BUT also should investigate possibility of paraneoplastic syndrome
What effect can hypoalbuminaemia have on calcium levels in CKD
Less protein bound calcium can lead to underestimation of biologically active calcium and mask hypercalcaemia
Signs of acute kidney injury
Vague; dull, inappetant
Oliguria more common than anuria
Difference between hypovolaemia and dehydration
Hypovolaemia = loss of water from the circulation
Dehydration = loss of body water
What can be a drug related cause of internal haemorrhage
Phenylephrine administration causnig rupture of great vessels of spleen in older horses
Blood results in haemorrhagic shock
High lactate due to poor tissue perfusion
Pre-renal azotaemia due to poor renal perfusion + just small volume urine
No evidence of blood loss immediately (takes ~24hrs for protein and RBCs to drop)
Why doesn’t PCV drop for 24hrs in acute blood loss
Due to splenic reserves and catecholamine induced contraction of spleen following tissue hypoxia
What nephrotoxins can cause acute kidney injury
NSAIDs
Aminoglycosides
Bisphosphonates
Pigment
When is NSAID toxicity most likely
In sick, dehydrated horses recieving IV NSAIDs
What type of antibiotics are aminoglycosides and how can we do the dosing to avoid tubular damage
= contration dependent
Small % of every dose goes to prox tubular epithelial cells
Key = using longer dosing intervals (>24hrs) to avoid accumulation and to allow some time where tubules are not exposed
Therapeutic drug monitoring is a good idea to check that drug concentration gets down to 0
What are bisphosphonates and how can we reduce risk of kidney damage
= used to reduce osteoclastic activity in bones
Do not use if impaired renal function
Do not use concurrently with NSAIDs
Give adequate access to water
How do pigments cause kidney damage
Oxidative damage
Two types of pigment nephropathy and how might we get them
Myoglobin: muscle injuriies, hypoglycin A, myopathies
Haemoglobin: haemolysis e.g from IMHA, neonatal isoerythrolysis
If we see myoglobin pigment in urine what should we look for on the bloods
Evidence of myopathy; CK and AST
What is the most common cause of pigmenturia
Atypical myopathy
What is acute glomerular nephritis and how do we diagnose
= nephrotic syndrome; biopsy shows immune complexes
May see with other autoimmune diseases
What does biopsy of acute interstitial nephritis show
Interstitial oedema and infiltrate
Treatment for acute interstitial nephritis
Rare condition; rapid increase in urea and creatinine
Give corticosteroids but poor prognosis
Treatment principles for AKI
Get rid of risk factors e.g NSAIDs, haemorrhage
Replace and maintain fluids with IV therapy Can use furosemide to reduce metabolic demands on cell to save tubular cells (inhibits Na/K ATPase) + cause diuresis
Clinical signs of chronic kidney faliure
WEight loss, inappetance, PU/PD, oedema, lethargy,
May have uraemic syndome
Tend to look good UNTIL there is loss of protein
What are the signs and aetiology of glomerulonephritis
Immune mediated deposition of immune complexes on glomerulus BM
see haematuria and proteinuria
Poor prognosis
Differentiate chronic renal disease from acute
Urine is isothenuric (rather than concentrated)
Azotaemia often very marked
Mild anaemia
Hypoalbuminaemia
Electrolytes: high K+, low Na+/Cl-, high Ca2_
Treatment of chronic kidney disease
palatable diet highly caloric diet without starch/sugar
Very poor prognosis once thin due to low albumin
What is idiopathic renal haemorrhage and how do we treat it
= spontaneous severe haemorrhage
May respond to steroids
Consider nephrectomy if unilateral
What is oliguria
Reduced urine output
- Can be absolute or lack of expected urine output given fluid therapy
What is pollakiuria
Increased frequency of urination
- Must differentiate infcreased frequency from increased VOLUME with polyuria causing higher freq
What other things could cause apparant strnguria
GI pain e.g from ulcers, meconium impaction
What does hyposthenuric urine show
Active water secretion since more dilute than plasma
= indicative of CKD, psychogenic PD, diabetes insipidus
What drugs can cause urine to appear isosthenuric
Sedatives (may have been used during catheterisation)
What can intermittent haematuria e.g after strenuous exercise be a sign of
Calculus
How common are primary UTIs
rare
Because normal flora is protective+ bladder has protective mucous
What things can predispose to secondary cystitis
Urethral damage e.g from breeding, parturtion, iatrogenic
Abnormal anatomy
Urolithiasis
Bladder paralysis
Bladder neoplasia
Sterile inflammatory cystitis leading to opportunistic infection
What is a good first line antibiotics for UTIs
TMPS since this is concentrated in the urine
What counts as proof of infection in urine
Quantitive culture from catheter showing >10 leukocytes/hpf
Haematuria possible causes (renal, bladder, urethra)
- Renal: idiopathic haemorrhage, neoplasia, cystic structures
- Bladder: stones, idiopathic haemorrhagic cystitis, bacterial cystitis, neoplasia
- Urethra: neoplasia, colliculus seminalis inflammation in geldings
+ haemolysis; not true haematuria
If blood coming from both kidneys rather than one on endoscopy what does this suggest
Due to haemolytic condition
If haematuria coming from just one ureter what are the likely causes
neoplasia, kidney stone, idiopathic renal haemorrhage, cystic change
Where are uroliths found in horses
Bladder (very rare to be urethral or ureteral)
3X more likely in geldings
Are uroliths related to UTIs
Doesn’t seem likely since geldings most predisposed to stones but mares get more UTIs
Are uroliths diet induced
NO - all have forage and excrete clacium via kidneys
What clinical signs might a horse with nephroliths show
[normally asymptomatic]
Can show pain when ridden, biting signs
May try blocking kidney to see if it removes the pain before removing kidney
When would we consider nephrectomy for neprholith
If causing signs and animal NOT azotaemia
Clinical signs of cystoliths
Haematuria after exercise
Concurrent UTI signs
Stranguria/dysuria
Treatment of cystoliths in horses
Need surgery = perineal urethrotomy and cystoscopy guided stone removal
What infectious cause of urinary incontinence must we consider/rule out
EHV-1 myeloencephalopathy
What are the common causes of incontinence
Related to neurological dysfunction or idiopathic
POssible causes of urinary incontinence
- Sabulous cystitis
- Sacrococcygeal injury; trauma
- Bladder calculi
- EHV myeloencephalitis/opathy
- Polyneuritis equi
- Sacral abscessation
- Sacral neoplasia
What do we tend to find with incontinence due to sacral trauma
Issue is LMN supply to bladder; feel atonic distended bladder with incomplete emptying and overflow dribbling
What do we look for when trying to work out if urinary incontinence could be EHV-1 myeloencephalopathy
Ask about vaccination, travel etc
Look for cauda equina signs and ataxia e.g weak anal tone, poor perineal sensation, pelvic limb ataxia, gluteal atrophy
What is equine sabulous cystitis
When calcium crystals accumulate as seidment in the ventral spect of bladder
Can become so heavy it pulls the bladder over the pelvic brim
See thick yellow sludge of protein, bacteria, ammonia WBCs, RBCs, mucus, chalk
Diagnosis and treatment of equine sabulous cystitis
Diagnosis = cystoscopy
Treatment = repeated bladder lavage, treat inflammation and secondary infections
NB: poor prognosis
At what urine concentration is it worth investigating suspected PU/PD further
<1.012
What medical diseases can we check for that may be causing PU/PD and how
Liver via GGT
PPID via ACTH test
Diabetes mellitus via fasted glucose test
Chronic kidney failure via urea/creantinine
When do we want to avoid water deprivation test
If chance horse may be in chronic kidney failure
If horse is able to concentrate urine during water deprivation test what does it have
Psychogenic polydipsia
If horse cannot concentrate urine during water deprivation test and becomes dehydrated what does it have
Diabetes insipidus
What tumours of the penis are common
Squamous cell carcinoma; starts as papilloma then neoplastic transformtaino
Melanoma = pigmented solid mass
Treatment for equine genital squamous cell carcinoma
Early resection, remove lots of penis and do perineal urethrostomy
Can try local chemo?….
