Urinary Tract Disease Flashcards
Define: azotemia
abnormal increase in the concentration of non-protein nitrogenous wastes in blood
How much must GFR decrease before azotemia develops?
25%
How much of the nephron population must be non-function for renal failure to occur?
75%
What general signs are associated with renal disease?
o PU/PD, dehydration, melena/hematemesis/vomiting
o Anorexia / GI signs / weight loss (uremia causes GI ulceration)
o Pale mucous membranes (EPO not produced)
o Lethargy
o Blindness (angiotensin II —> vasoconstriction —> high BP)
o Distended abdomen
Define: uremia
the clinical signs and biochem abnormalities associated with critical loss of functional nephrons
Differentiate gross hematuria, occult hematuria, and pseudohematuria.
Gross (macroscopic) - sufficient blood to be apparent to the naked eye
Occult (microscopic) - present but not visible to the naked eye
Pseudo - red to brown urine w/o intact RBC, instead d/t hemoglobin, myoglobin, or chemicals
What is the gold standard measurement of GFR?
What indirect measurement is most commonly used?
Clearance of radioisotopes with renal scintigraphy
Serum creatinine
What are the 4 limitations of using creatinine as a measure of GFR?
- does not tell you why GFR has fallen
- does not discriminate between causes of azotemia, ARF/CRF, or reversible/irreversible renal failure
- severity of CS are not directly proportional to magnitude of increase
- cannot prognosticate magnitude of azotemia
What parameters (5) are evaluated on a urine dipstick?
Protein pH Blood Glucose Ketones
What is considered ‘normal’ SpGr of urine in the dog and cat?
Dog >1.030
Cat >1.035
What is assessed with fractional excretion of electrolytes?
Which electrolyte is most commonly analyzed?
Assessment of tubular dysfunction
Na-fractional excretion (compared to Cr) differentiates prerenal (1%) disease
How is proteinuria detected?
What are the parameters to diagnose proteinuria in cats and dogs?
What condition might give a false positive in this test?
UPC
Cats >0.4 (0.2-0.4 borderline)
Dogs >0.5 (0.2-0.5 borderline)
LUTD causes false positive
What are 5 main ddx for renomegaly?
- Neoplasia
- Renal inflammation
- Amyloidosis
- Hydronephrosis
- Portosystemic shunts
- Polycystic kidney disease
Which renal tumors are more common in dogs?
Describe the CS, Dx, Tx, and prognosis.
Adenocarcinoma
♣ CS: few early on (only affects one kidney), hematuria, weight loss, unilateral renomegaly, rarely azotemia, polycythemia (paraneoplastic), hypertrophic osteopathy (paraneoplastic)
♣ Dx: renal US with FNA
♣ Tx: nephrectomy
♣ Prog: MST 16 months with treatment, ~50% have metastases at diagnosis
Which renal tumors are more common in cats?
Describe the CS, Dx, Tx, and prognosis.
Lymphoma
♣ Usually affects both kidneys
♣ CS: renomegaly, weight loss, inappetence, PU/PD, renal azotemia, tends to spread to CNS
♣ Low to moderate association with FeLV infection
♣ Dx: renal US with FNA
♣ Tx: multi-agent chemotherapy (COP or CHOP), may resolve the azotemia
♣ Prog: 60% complete remission, MST 91 days with treatment
Is acute kidney injury considered reversible?
Yes
What parameters are assessed in IRIS staging of acute renal failure?
Blood Cr concentration
Non-oliguric / oligoanuric
Describe the first (initial) phase of acute renal failure
- Initial (onset)
- no clinical signs
- usually triggered by an ischemic event
- definable by a decrease in urine output or increase in creatinine
Describe the second (extension) phase of acute renal failure
- Extension
- continued hypoxia and inflammation, damaging to PT and LOH
- compromised Na/K pumps leads to cell swelling and death
- increased cytosolic calcium
- loss of brush border or apical and basal cell surfaces
Describe the third (maintenance) phase of acute renal failure
- Maintenance
- 1-3 weeks duration
- urine output may be increased or decreased
- urine is ultrafiltrate
Describe the fourth (recovery) phase of acute renal failure
- Recovery
- heralded by polyuria and extreme Na loss
- may take months
What are the risk factors for ARF?
dehydration hypovolemia anesthesia hypoxia SIRS
What is normal urine output?
What is considered abnormal?
1-2 ml/kg/hour
Abnormal
What is normal CVP?
0-10 cmH2O
What fluid bollus should be given to patients at risk for ARF?
10-15 ml/kg crystalloids
2-5 ml/kg colloid
What 5 diagnostic parameters are indicators of ARF?
- Reduced urine output (abnormal 1%
- Renal tubular biomarkers
o GGT(:Cr) present on the brush border in the tubule - increased GGT (compared to Cr) indicates tubular damage
o N acetyl glutamate (NAG:Cr) found inside cells of proximal tubules - acute injury/swelling/rupture of cells indicates tubular damage
What fluid administration is appropriate to treat ARF?
- Correct shock: over 60 minutes, 15 minute interval boluses
♣ 60-90ml/kg (canine) / 45ml/kg (feline) - Correct dehydration: over 6-12 hours, crystalloids (LRS, normosol R) or 0.9% NaCl (if hyperK+)
♣ % dehydration x 10 x BW = …mL
♣ Reduce sodium content once hydrated 0.45% NaCl + 2.5% dextrose - Ongoing fluid requirements: maintenance usually around 60ml/kg/day, but in ARF urinary losses vary
♣ Insensible fluid loss = 22ml/kg/day
♣ Ongoing fluid losses = estimate vomiting, diarrhea, etc.
♣ Urinary losses = monitored directly (usually ~44ml/kg/day)
What is the shock dose of fluids in the dog and cat?
Dog 60-90ml/kg
Cat 45ml/kg
How are dehydration replacement fluids calculated?
% dehydration x 10 x BW = … mL
How much fluid is lost “insensibly”?
22ml/kg/day
How is mannitol used to treat oliguria?
When is it contraindicated?
Osmotic diuretic, increases circulatory volume
Contra: anuria, dehydration
How is furosemide used to treat oliguria?
When is it contraindicated?
Loop diuretic, inhibits Na/K/2Cl symporter in LOH and decreases Na/K/ATPase pump
Renoprotective d/t increased urine production without increased GFR
Contra: dehydration, lethargy, tachycardia, ototoxicity
How is dopamine used to treat oliguria?
When is it contraindicated?
May convert to non-oliguria
Only benefit as a pressor when ARF secondary to CO failure or severe hypertension
Contra: cats
How are Ca-channel blockers used to treat oliguria?
When is it contraindicated?
Pre-glomerular vasodilation
Renoprotective
What is extracorporeal renal replacement therapy (ERRT) and when is it indicated?
Artificial porous membrane with artificial hydrostatic and solute concentrations to prevent solute loss
Indications: ♣ Fluid overload with pulmonary edema ♣ Hyperkalemia ♣ Progressive azotemia ♣ Acute toxicity
What is the specific therapy for ARF caused by ethylene glycol?
4-methylpyrazole
What is the specific therapy for ARF caused by NSAIDs?
misoprostal
What is the specific therapy for ARF caused by leptospirosis?
penicillins and doxycycline
What is the specific therapy for ARF caused by pyelonephritis?
culture
fluoroquinolones or TMS (4-6 weeks)
What is the specific therapy for ARF caused by aminoglycoside toxicity?
ticarcillin IV
3rd gen penicillin, binds with gentamycin
What is the specific therapy for ARF caused by TMS toxicity?
urinary alkalinazation
How is hyperkalemia secondary to ARF managed?
insulin followed by dextrose
calcium gluconate
How is acidosis secondary to ARF managed?
HCO3 administration IV
calculated by base deficit x BW x 0.3
How is hypocalcemia secondary to ARF managed?
calcium gluconate 10%
How is hypercalcemia secondary to ARF managed?
diuresis / ERRT
furosemide / glucocorticoids
calcitonin
biphosphates
How is hyperphosphatemia secondary to ARF managed?
protein restriction diet
aluminum hydroxide/carbonate
Why is hypertension a complication of ARF?
How is hypertension secondary to ARF managed?
Secondary to RAAS activiation and fluid overload
amlodipine (Ca-channel blocker)
hydralazine (smooth muscle vasodilator)
How are GI symptoms secondary to ARF managed?
uremic gastropathy
-omeprazole, pantoprazole
prokinetics
-ondansteron, metoclopramide
antiemetics
-metoclopramide, maropitant
What is the progression of chronic kidney disease, including when urine concentrating ability is impaired and when azotemia develops?
CKD nephron disease and loss >66% loss =urine concentration impaired >75% loss = azotemia further progression, uremia
Describe the (6) secondary effects of CKD and their etiologies.
- Failure of excretion of nitrogenous wastes –> uremia
- Failure of urine concentration –> PU/PD
- Failure to synthesize calcitriol –> hypoCa and renal secondary hyperPTH
- Failure to synthesize EPO –> anemia
- Failure to catabolize peptide hormones (eg. gastrin) –> uremic gastritis
- Production of renin to increase GFR –> systemic hypertension
What is the general ‘clinical picture’ of a CKD patient?
PU/PD (+nocturia) and general NDR
Poor body condition
Pale mm
Small kidneys on palpation
What is expected on urinalysis of a CKD patient?
Isosthenuria (1.008-1.030 in cats, 1.008-1.022 in dogs)
Possible concurrent UTI
Proteinuria
What is expected on the biochemistry of a CKD patient? (5 components)
- Azotemia
- Hyperphosphatemia
- may not be apparent in stage I and II d/t compensation to increase phosphate loss - Hypokalemia
- reduced intake and increased loss - Calcium changes
- iCa often low
- hyperCa can occur secondary to renal failure or cause renal failure
- high Ca and P = metastatic calcification - Metabolic acidosis
- reduced excretion of H+
What is expected on hematology of a CKD patient?
What is the cause and what is the result of this abnormality?
Non-regenerative, normocytic, normochromic anemia
Cause (multifactorial):
- EPO deficiency
- decreased life span of RBC
- effect of PTH on bone marrow
- anemia of chronic dz
- GI hemorrhage
Effect:
-lethargy, inappetance, hypoxia
What factors affect how blood pressure is measured? (type of measurement, size of cuff)
Oscillometric - large patient
Doppler - small patient
cuff size 30-40% of circumference
What are the general goals of management of CKD by IRIS staging?
Stage I: identify primary dz and start specific therapy
Stages II-III: renoprotective therapy to slow progression
Late stage III-IV: symptomatic
How is pyelonephritis (UTIs) secondary to CKD treated?
Abx 4-6 weeks, must have renal excretion and UUT penetration
eg) amoxicillin, cephalosporins, TMS, fluoroquinolones
How is dehydration secondary to CKD treated?
Control losses (vomiting/diarrhea)
Short term: fluids (IV/SQ)
Long term: oral/SQ fluids, feeding tube placement
How is anorexia secondary to CKD treated?
Appetite stimulants:
cyproheptadine (cats)
mirtazapine (cats and dogs)
At what IRIS stage of CKD is a renal diet indicated for dogs / cats?
Dogs - stage III
Cats - stage II
How is anemia secondary to CKD treated?
What treatment should NOT be used?
EPO therapy (rHuEPO or darbopoeitin-alpha) indicated for symptomatic animals with PCV
How is hypertension secondary to CKD treated in dogs / cats?
Dogs: ACE inhibitors (benazepril)
Cats: Ca channel blockers (amlodipine)
Angiotensin receptor blocker (Telmisartan) also licensed for reduction of proteinuria associated with CKS in cats
What is ‘acute on chronic’ kidney disease?
How is it managed?
CKD + inciting cause of AKD
Identify and treat underlying cause
Treat dehydration and optimize GFR with IV fluids
Monitor urea, Cr, P, and electrolytes
What is the prognosis for dogs / cats with CKD?
Dogs: up to 1-2 years
Cats:
-IRIS stage II MST 2 years
-IRIS stage IV MST 1 month
What are the 3 component of a glomerulus?
- Juxtaglomerular cells: release renin
- Mesangial cells: endothelial cells holding capillary beds together
- Bowman’s capsule: parietal layer of epithelial cells + podocytes surrounding capillary beds
What are the causes of proteinuria?
Physiological - strenuous exercise, seizures, fever, stress
Pre-renal - abnormal concentrations of proteins presented to kidney
Renal - defected renal function or inflammation (glomerular/tubular)
Post-renal - inflammation of the ureter, bladder, urethra, or prostate
What is the first diagnostic test that will pick up proteinuria?
Urine dipstick
Which protein is the urine dipstick most sensitive to?
What can give false negatives and positives?
Albumin
False positive:
alkaline urine
contamination
False negative:
acidic urine
Bence-Jones proteins (multiple myeloma)
How is proteinuria quantified?
What value is considered proteinuria in dogs /cats?
24-hr urine protein measurement (gold standard, but rarely done)
UPC (can only evaluate if urine sediment negative)
Dogs: >0.5
Cats: >0.4
What UPC values generally indicate PLNs (glomerular pathology)?
UPC 2.0-8
What is the main pathology in glomerulonephritis?
Immune complexes deposited in the glomeruli
What are the 4 etiologies for glomerulonephritis?
- Chronic antigenic stimulation (inflammation, infection, neoplasia)
- Idiopathic
- Familial
- X-linked hereditary PLN of Samoyeds
- Alport syndrome of cocker spaniels - Amyloid depositis
(In addition to history, PE, and MDB) What is involved in the workup for glomerulonephritis?
(4 components)
- Systolic blood pressure
- low protein, edema
- high protein, end-organ damage - 4Dx (Borrelia, Dirofilaria, Ehrlichia, Leishmania)
- Screen for neoplasia
- Hypercoagulability test
- thromboelastography (direct)
- PLT, antithrombin, fibrin, d-dimers (indirect)
What is nephrotic syndrome?
Kidney disease characterized by edema and loss of protein from the plasma into urine d/t increased glomerular permeability
- Proteinuria
- Hypoalbuminemia
- Ascites
- Hypercholesterolemia
Often systemic hypertension
How is glomerulonephritis treated?
What considerations should be made regarding the tx?
Immunosuppresive therapy
- Mycophenolate (DOC)
- Glucocorticoids
Indicated when proteinuria is confirmed to be glomerular in origin and a biopsy confirms ICGN
Contraindicated with pancreatitis, bone marrow suppression, DM
How is hypercoagulability secondary to glomerulonephritis treated?
Aspirin
Clopidogrel
What are the 4 outcomes possible with urethral obstruction?
- Acute unilateral (clinically silent)
- Acute bilateral (uncommon, emergency)
- Big kidney-little kidney (past obstruction causing one kidney to become fibrotic, subsequent obstruction of contralateral)
- Bilateral CKD + ureteral obstruction (most guarded prognosis)
What signalment is associated with ureteral obstruction?
Cats > 7 years
What clinical signs are associated with ureteral obstruction?
Acute uremia
Anorexia, depression
Vomiting
Oligo/anuria
What diagnostic tests can be used in ureteral obstruction cases?
Rads (don’t confuse with normal renal pelvic calcification)
US (hydronephrosis)
CT
How is ureteral obstruction managed (4 options)
- Medical (20-30% resolve within 3-4 days)
- fluids and pain management
- mannitol for oliguria
- prazosin and amitryptilline (ureteral relaxants) - Lithotripsy (excellent in dogs, poor for cats)
- Ureteral stents (standard of care!)
- SUB
What are 3 etiologies for urethral obstruction?
- Idiopathic cystitis/urethritis
- Cystic calculi
- Decreased luminal diameter (stricture, idiopathic urethritis, urethrospasm)
How is urethral obstruction diagnosed?
- Enlarged bladder (esp. male cats)
- Signs of forced urination
- Difficulty in manually expressing urine
- Resistance during passage of urethral catheter
What initial stabilization and testing should be done with urethral obstruction?
Heat Fluids ECG (hyperK common) BUN/Cr, lytes, acid/base Therapeutic cystocentesis
How is hyperkalemia treated in an emergency?
4 options
- Shock rate fluids
- Calcium gluconate for cardioprotection
- IV insulin
- Bicarbonate (not required unless severely acidotic)
How is urethral obstruction managed?
Preparation:
- anesthetize
- cytocentesis
- penile extrusion
- catheterization
- Retrograde flushing
- Penile/rectal massage
What clinical signs are associated with non-obstructive LUT disease?
Dysuria, pollakiuria, periuria, stranguria, pigmenturia
Incomplete voiding
Urinary incontinence
What does yellow/orange urine indicate?
Red urine?
Yellow/orange: bilirubin
Red: hematuria, hemoglobin, myoglobin
DDx for hematuria (source of blood)
Renal
LUT
Reproductive (prostatic, vaginal, uterine)
Systemic dz (bleeding disorder, hypertension, hyperviscocity)
What two bacterial types are most commonly found in UTIs?
E. coli, gram+ cocci
How are uncomplicated UTIs treated?
Amoxicillin, cephalosporins, TMS
10-14 days
HDSD of enrofloxacin
What is a reinfection UTI and how is it treated?
New or different organism found >7 days after tx course
Nitrofurantoin good choice
- bedtime admin at 30-50% original dose
- culture q4 weeks during tx -q1 month for 3 months after tx
- q3 months for 1 year
What is a superinfection?
New or different organism found at day 7 after beginning tx
What is a relapse infection?
Same organism found 7 days after tx course
T/F, crystalluria = urolithiasis
False, it may indicate urolithiasis or may simply indicate urine has been supersaturated
What signalment and predisposing factors are associated with struvite crystals?
Schnauzer, Lassa apso, cocker spaniel, shit tzu, bisson friesse
Dogs: UTIs with urease-producing bacteria and high urine pH
Cats: alkalinizing agents in diet
How are struvite crystals treated?
Dietary (Hills s/d) to acidify
What signalment and predisposing factors are associated with calcium oxalate crystals?
Schnauzer, Lassa apso, mini poodle, yorkies, shit tzu, bisson friesse
Male dogs
Obesity
Acidic urine
Hyperparathyroid (hyperCa in urine)
How are CaOx crystals treated and prevented?
Tx: surgical
Px: Diet (Hills U/d) with potassium citrate
Thiazide diuretics (hydrochlorothiazide)
Potassium citrate
What breeds are associated with cysteine crystals?
Australian cattle dogs, Daschnunds, Newfoundlands, bulldogs
How are cysteine crystals treated?
Alkalinize urine (Hills u/d) Thiol drugs to bind cysteine
What signalment and predisposing factors are associated with urate crystals?
dalmatians, black Russian terrier, bulldog
Hepatic dz
Genetic tubular defects
Male dogs
Acidic urine
How are urate crystals treated?
Tx hepatic dz
Hills u/d
Xanthin oxidase inhibitors for Dalmatians (allopurinol)
What are the risk factors for FLUTD?
Age 2-6 years Litter box use Dry cat food Inactivity and obesity Stress Spring / winter
What are the clinical signs of FLUTD?
Hematuria, stranguria, pollakiuria, inappropriate urination
Palpable large firm bladder
Inability to urinate or periuria
What is expected in a FLUTD urinalysis?
Protein, blood, crystals
Negative bacterial culture
How is FLUTD treated?
Environmental enrichment
Dislodge obstructions
Opioids as needed
What types of neoplasia are found in the LUT?
TCC (most common)
-Scotties predisposed
Leiomyoma/sarcoma SCC Adenocarcinoma Fibrosarcoma Hemangiosarcoma
What treatment is indicated for TCCs?
Surgical if small and does not involve trigone
Chemo (mitoxane +/- piroxicam)
Photodymanic therapy
Urine diversion
Describe the urinary cycle
Passive phase of filling (reservoir)
o Innervated by L1-4 (hypogastric)
♣ Activate beta-receptors to allow stretching
♣ Activates a1-receptors of the trigone and proximal urethra
♣ Blocks PSNS outflow
Active phase (voiding)
o Reflex: stretch receptors pelvic n. spinal cord brain stem PSNS outflow (pelvic n. S1-3)
o Contraction of muscle fibers of bladder wall
o Inhibition of pudendal n. decreased urethral sphincter tone
♣ Can be overridden by the cerebrum
How does UMN disease cause micturition disorders?
How is this dx and tx?
Detrusor areflexia with sphincter hyperreflexia
Dx: bladder difficult to express
Tx: baclofen (antispasmotic)
How does LMN disease cause micturition disorders?
How is this dx and tx?
Detrusor areflexia and sphincter areflexia
Dx: bladder easily expressed, constant leakage
Tx: bethanecol + manual expression
How does detrusor-sphincter reflex dyssergia cause micturition disorders?
How is it tx?
Initiation of detrusor contraction causes urethral sphincter spasms
Tx: alpha-adrenergic blockers (phenoxybenzamine)
How does detrusor atony cause micturition disorders?
How is this dx and tx?
Occurs d/t overfill (obstruction)
Dx: large flaccid bladder, normal neuro exam
Tx: manual expression, will resolve 7-10 days
How does detrusor instability/hyperreflexia cause micturition disorders?
How is this dx and tx?
Contraction during storage of urine or low compliance of detrusor m.
Dx: cystometrography
Tx: anticholinergic drugs (oxybutynin, dyclomine)
What disease causes 85% of incontinence cases?
Urinary Sphincter Mechanism Incompetence (SMI)
Intravesicular pressure (within bladder) > urethral pressure
Describe the two etiological theories for urinary SMI
Pressure transmission theory
-when urethral neck not in abdominal cavity it is not subjected to the same pressures as the intra-abdominal bladder
Hammock theory
-anatomical structures maintaining the position of the bladder and urethra are abnormal
How is urinary SMI diagnosed?
Urethral pressure profiles (if available)
CS, signalment, r/o other causes
How is urinary SMI treated?
alpha-1 agonists (ephedrine, PPE)
Estriol - increases striated m. in sphincter
Collagen injection at cranial urethra
Surgical: artificial urethral sphincter placement
