Lecture 27: Medical diseases of equine renal and urinary systems Flashcards
What is function of renal system
Excrete nitrogenous waste and control fluid and ion balances
How much water should horse consume/ day
60-65ml/kg/day- 23L or 6 gallons ~5% BW
What is the GFR per day in horse
2ml/kg/min-1400L/day- 370 gallons
What does the proximal tubule absorb
Glucose, amino acids, electrolytes and water
Urine becomes more ___in Loop of henle
Concentrated
What part of LOH is permeable to water, but impermeable to solutes
Descending limb
What part of LOH is impermeable to water, but permeable to solutes
Ascending
Where does furosemide block
NaKCC in ascending loop of henle
What does distal tubule secrete
Calcium, potassium and acid
What channel does water leave through in collecting duct and what hormone controls it
Aquaporins controlled by ADH
What is USG for hyposthenuria
<1.008, very dilute
What is USG for isothenuria
1.008-1.014
What is the USG for concentrated urine
1.025-1.050
Foals urine should be ___
Hyposthenuria
Chronic renal failure produces USG of ___
1.008-1.025
What is the normal pH of urine
7-9
Paradoxical aciduira is seen with ___
Hypokalemia, hypochloremic metabolic alkalosis
What urine protein: creatinine ratio is too high
> 2:1
Glucose should be ___in urinalysis
Negative
What test can you run for myoglobin
Ammonium sulfate precipitation
What is bilirubin associated with
Intravascular hemolysis, hepatopathy
Pyrua has a WBC > ___
10
Hematuria has a RBC > __
5
What tests do you run if PU/PD patient signlament is consistent with PPID or EMS
ACTH, insulin, glucose
What challenge/test can you run for PU/PD diagnostic, how does it work and what are some possible results
Water deprivation test
Normal renal function USG>1.045
Concentrated urine- psychogenic polydipsia
Noncentrated: run vasopressin tests
What is acute renal failure classified by
abrupt decrease in GFR associated with failure to excrete nitrogenous wastes causing azotemia, electrolyte imbalances, acid base disturbances
What are some causes of acute renal failure
- Decreased renal perfusion- hypovolemia (Pre renal, or ischemic)
- Acute tubular necrosis (NSAIDS)
- Interstitial nephritis or glomerulonephritis
- Post renal- elevated creatinine
What condition in foals can cause post-renal ARF, elevated creatinine in peritoneal fluid
Bladder rupture
What is anuria
No urine
What is oliguira
Decreased urine
What are some clinicopathologic findings associated with ARF
Increase BUN, creatinine
What % of nephrons have lost function before azotemia is noticing
75%
What test is a sensitive early maker or declining GFR
SDMA
What electrolyte imbalances are seen with ARF
Hyponatremia, hypochloremia, hypocalcemia, hyperphosphatemia, metabolic acidosis
What is tx for ARF
- Fluids- saline or balanced electrolyte solution
- Furosemide
If hypernatremic in ARF what can you give
Dextrose
What is the most important prognostic indicator for ARF
Duration of ARF and if continue oliguria
What is prognosis for creatinine <5 and >10
Less than 5- good
>10 grave
What are some characteristics of CRF
Loss of ability to concentrate urine, retain metabolic waste, alterations in electrolytes, acid-base
What are some causes of CRF
- Congenital anomalies
- Acquired: glomerulonehrphitis or interstitial nephritis caused by immune complex deposition
- Glomerular tubular injury: NSAIDs, hypoperfusion
What are some signs of CRF
Ill-thrift, weight loss, ventral edema, PU/PD, poor athletic performance, excess dental tartar, uremic breath
What is the USG of CRF
Isothenuria 1.008-1.012
What are the classic electrolyte disturbances associated with CRF
Hyponatremia, hypochloremia, hyperkalemia, hypercalcemia, hypophosphatemia
How can you manage CRF
- Short term IV fluids
- Avoid alfalfa
- Encourage appetite
- Vitamin E and C
- Omega 3 fatty acids
T or F: diuretics are useful in CRF
False
What is the expected lifespan in CRF for creatinine <5, 5-10 and >10
<5: >18 months
5-10 <18 months
>10 days to weeks
Case example: 20yr Morgan gelding presented with urine dribbling for weeks to months, 8/9 BSC what are some differentials
Neurological disease, urolithiasis/cystitis, congenital, trauma, tail injections, neoplasia
What does the pudenal nerve innervate
Striated muscle of urethra
What does hypogastric nerve supply
Sympathetic nerve supply
What does pelvic nerve supply
Parasympathetic nerve supply
Contraction of bladder is controlled by __nerve supply
Parasympathetic
What are some signs of lower motor neuron bladder
Loss of detrusor function, dribbling, large easily expressible bladder, loss of anal and tail tone
What are some signs of upper motor neuron bladder
Initially increased urethral resistance, turgid bladder (colic)
What are 2 causes of sabulous urolithiasis
- Secondary to neurogenic bladder
- Primary sabulous accumulation secondary failure to empty
What is prognosis for sabulous urolithiasis
Grave
Patients with sabulous urolithiasis usually prevent with ___
Incontinence/dribbling
What is tx for sabulous urolithiasis
Removal with 0.25% acetic acid, bethanecol, phenoxybenzamine
What does bethanecol do to tx incontinence
Improve destrusor function
What does phenoxybenzamine do to tx incontinence
Decrease urethral tone
What is the top differential diagnosis for Hematuria
Urolithiasis/cystourolithaisis- usually associated with exercise
What are some clinical signs of urolithiasis/ cystourolithiasis
Hematuria with exercise, normal renal function with chemistry and urinalysis
What urinary stones are yellow-green speculated, easily fragmented
Calcium carbonate
What urinary stones are gray white smooth, resistant to fragmentation
Calcium carbonate phosphate
Renal idiopathic Hematuria is common in what breed
Arabians
What are some signs of renal idiopathic Hematuria
Clots of blood in urine, endoscopic exam reveals clots of blood in 1 or both ureters
What is the most common urinary tract neoplasms
Urethral and external genitalia tumors
What is the tx for renal neoplasms
Remove kidney
What is the most common complaint for bladder neoplasms
Hematuria
What is the most common bladder neoplasm in horses
Squamous cell carcinoma
Pyelonephritis and ureteritis are associated with upper or lower urinary tract infections
Upper urinary tract
Which is a life threatening urinary tract infection: upper or lower
Upper
Is cystitis and urethritis associated with upper or lower urinary tract infections
Lower
What breed is genetically predisposed to renal tubular necrosis
Fresians
What is the inciting cause of renal tubular necrosis
Drugs- SMZ, antibiotics
What clinical pathologies are associated with renal tubular acidosis
Decreased bicarbonate, hyperchloremia, metabolic acidosis
What is the distal type I renal tubular acidosis
Can’t secrete H+
What is the proximal type II renal tubular acidosis
Can’t reabsorb bicarbonate
What is tx for renal tubular acidosis
Bicarbonate IV, potassium supplementation, sodium bicarbonate PO (baking soda)