Urinary Flashcards
What are the 2 most common bacteria in UTIs for small animals?
E. coli and Staph
What are the 2 most common bacteria in UTIs for horses?
E. coli and Strep
What are the 2 most common bacteria in UTIs for cattle?
E. coli and Corynebacterium renale
What is asymptomatic bacteriuria?
Bacteria in the urine from an individual that did not have any clinical signs
What is the recommended duration of treatment for small animals with first time UTIs?
1 week
What is the recommended duration of treatment for small animals with recurrent UTIs?
4 weeks
What is the recommended duration of treatment for small animals with prostatitis?
6 weeks
What is the recommended duration of treatment for small animals with pyelonephritis?
4-6 weeks
If the organism causing a UTI is susceptible to an antimicrobial, the urine should culture as sterile after how many days of therapy?
Urine should be sterile by 3 days of antimicrobial therapy
Name the first‐line antimicrobials used to manage uncomplicated UTIs
Amoxicillin Amoxicillin-clavulanic acid Cephalexin Trimethoprim-sulfonamide Fluoroquinolone
What is the standard first‐line antimicrobial for treating a prostatitis?
Fluoroquinolone (used for suspect prostatitis)
Broad spectrum or gram-negative:
Enrofloxacin
Chloramphenicol
TMS
Gram positive:
Clindamycin
Macrolides (erythromycin, azithromycin, clarithromycin)
What antimicrobials cross the blood‐prostate barrier?
Enrofloxacin Chloramphenicol TMS Clindamycin Macrolides (erythromycin, azithromycin, clarithromycin)
What antimicrobials are more active in acidic urine?
Beta-lactams
Methenamine
What antimicrobials are more active in basic urine?
Fluoroquinolones
Aminoglycosides
Macrolides
Discuss the pros and cons of methenamine use as a urinary tract antiseptic. Note the effect of urine pH and its suitability for cystitis versus pyelonephritis.
Methenamine is used for acidification of the urine
It is only used for cystitis
It cannot be used for pyelonephritis because the conversion of methenamine to formaldehyde is not rapid enough to occur when the urine is passing through the kidney
What antifungals are appropriate to manage a yeast/fungal UTI?
Renal aspergillosis:
You can try fluconazole
Voriconazole
Candida infections:
Fluconazole
Voriconazole
Nystatin infusions as a last resort
When treating a patient with a systemic aminoglycoside, what role do BUN or serum creatinine tests play in monitoring the patient for impending nephrotoxicity?
If these have increased, it is too late to be helpful
When treating a patient with a systemic aminoglycoside, what role do urinalysis tests play in monitoring the patient for impending nephrotoxicity?
Perform serial urinalyses and watch for:
Increasing tubular casts
Increasing protein
Possibly decreasing specific gravity and increasing glucose
When treating a patient with a systemic aminoglycoside, what role do urine GGT: urine CR ratio tests play in monitoring the patient for impending nephrotoxicity?
Perform serial urine GGT:Cr ratios
If they are increased more than 3x the baseline, caution should be taken
What procedure(s) do we perform to minimize the nephrotoxic risk of regular amphotericin B?
Increase renal perfusion
—Pretreatment with IV mannitol or
—Pre and post-treatment with IV isotonic saline diuresis
Lipid formulations avoid most of the nephrotoxic problems
Regular IV formulation diluted and give SC
What procedure(s) do we perform to minimize the nephrotoxic risk of regular cisplatin?
Slower infusion of the drug
Mannitol to increase GFR or furosemide
Pre and post-treatment with IV isotonic saline diuresis
How do the lipid formulations of amphotericin B minimize nephrotoxic risk?
The incorporation of amphotericin B into the lipid minimizes the drug contact with the renal artery so that much less vasoconstriction occurs and hence less renal toxicity
What disease or physiologic states predispose to NSAID‐induced nephrotoxicity?
Dehydration and other nephrotoxic drugs
In an NSAID overdose, what can we do to minimize the risk of nephrotoxicity?
Maintain adequate hydration
Avoid other nephrotoxic drugs
Misoprostol used to prevent/treat NSAID GI ulcers may also protect the kidney
Possibly use COX-2 selective NSAIDs
Under what conditions would the risk of crystalluria be an issue for sulfonamides? What about potentiated sulfonamides?
This is only a problem with new sulfas if the animal is dehydrated
Explain the concept of “ion trapping” as it relates to management of toxicities
Traps the toxin in its ionized for in the urine where it can be excreted
What are the effects of urine pH with DL methionine?
Acidifier
What are the effects of urine pH with ammonium chloride?
Acidifier
What are the effects of urine pH with potassium citrate?
Alkalizer
What are the effects of urine pH with sodium bicarbonate?
Alkalizer
What are the contraindications for ammonium chloride administration?
Contraindicated in liver disease, kidney disease, or metabolic acidosis
The efficacy of cranberry extract in preventing recurrent UTIs is not established. What is the proposed mechanism of benefit based on ex vivo studies?
Ex vivo studies indicate proanthocyanidins (PACs) or condensed tannins in cranberry juice extract had no bacteriostatic or bactericidal affect, but inhibited bacterial adherence to canine uroepithelial cells
Discuss the appropriate management of urate urolithiasis in a Dalmatian
Alkalize the urine to decrease the risk of urate stones
Diet modification to be low in purines (Purines produce xanthine oxidase which turns xanthine to uric acid)
Allopurinol inhibits xanthine oxidase (Dietary protein and purine intake must be reduced with this)
What immunosuppressive drug does allopurinol interact with such that severe bone marrow suppression can result?
Azathioprine
Allopurinol has antiprotozoal activity against what organism?
Leishmania
What are the receptors activated and the utility of a dopamine at low CRI disage?
D1 dopamine receptor stimulation vasodilates renal and splanchnic vessels
What are the receptors activated and the utility of a dopamine at medium CRI disage?
Beta-1 receptor stimulation to increase inotropy of heart
What are the receptors activated and the utility of a dopamine at high CRI disage?
Alpha-1 receptor stimulation causes vasoconstriction
How does fenoldopam differ from dopamine?
Fenoldopam is a selective DA-1 agonist with no α or β effects
Fenoldopam has a higher affinity for feline dopamine receptor than dopamine
It improves RBF, GFR, and urine production
- Why are ACE inhibitors useful in the management of protein‐losing nephropathies?
Preferentially vasodilate efferent arterioles of the glomerulus and decrease filtration pressure
Decrease proteinuria
—Reabsorption of filtered proteins can injure the interstitium of the kidney by activating intracellular events and the release of vasoactive and inflammatory mediators
Why is it recommended to check the BUN/Cr of a patient recently placed on an ACE‐inhibitor?
To check for prerenal azotemia from hypertension, not nephrotoxicity
What is the site of action of osmotic diuretics? Example?
Glomerulus
Example: Mannitol
What is the site of action of carbonic anhydrase inhibitors? Example?
Proximal renal tubule
Examples: Acetazolamide oral; Dorzolamide and brinzolamide topical ophthalmic
What is the site of action of loop diuretics? Example?
Works in the thick ascending loop of Henle by blocking the Na, K, and Cl symporter
Examples: Furosemide; Torsemide
What is the site of action of thiazide diureitcs? Example?
Works in the distal convoluted tubule to block Na, Cl symporter
Examples: Chlorothiazide
What is the site of action of potassium sparing diuretics? Example?
Acts on the distal parts of the nephron from the late distal tubule to the collecting duct
Example: Aldosterone antagonists- spironolactone
Of the classes of diuretics, which is the most intense such that it can continue to cause diuresis in the face of severe dehydration?
Loop diuretics such as furosemide
What are the renal and nonrenal uses of mannitol?
Renal:
Protective effect in renal hypoperfusion
Oliguric renal failure
Nonrenal: Cerebral edema (osmotically draws fluid from the tissue into the blood) Acute glaucoma (osmotically draws fluid from the tissue into the blood)
What are the contraindications for administering mannitol?
Active CNS hemorrhage
Congestive heart failure
Use cautiously in renal failure
Why is active CNS hemorrhage a contraindication for administering mannitol?
In active bleeding in the brain, mannitol is incorporated into the hematoma and continues to draw fluid to it, increasing intracranial pressure
Why is congestive heart failure or pulmonary edema a contraindication for administering mannitol?
Volume overload
Why should mannitol be used cautiously in renal failure?
Volume overload if not excreted by the kidney
Give 2 or fewer test doses to establish effectiveness
Do not readminister if unresponsive to test doses as hyperosmolality will result
Which diuretics promote potassium loss?
Loop diuretics
Thiazide diuretics
Which diuretics promote potassium retention?
Potassium sparing diuretics
Which diuretics promote calcium loss?
Loop diuretics
Which diuretics promote calcium retention?
Thiazide diuretics
Which diuretics promote magnesium loss?
Loop diuretics
Thiazide diuretics
Which diuretics promote bicarbonate loss?
Carbonic anhydrase inhibiting diuretics
What is the appropriate diuretic treatment of choice for glaucoma?
Carbonic anhydrase inhibiting diuretic: dorzolamide and brinzolamide topical ophthalmic
What is the appropriate diuretic treatment of choice for equine hyperkalemic periodic paralysis?
Carbonic anhydrase inhibiting diuretic: acetazolamide oral
What is the appropriate diuretic treatment of choice for cerebral edema?
Osmotic diuretic: mannitol
What is the appropriate diuretic treatment of choice for acute congestive heart failure (first choice)?
Osmotic diuretic: mannitol
What is the appropriate diuretic treatment of choice for congestive heart failure that is diuretic refractory?
Potassium-sparing diuretics: sprinolactone
What is the appropriate diuretic treatment of choice for hypercalcemia due to vitamin D rodenticide or hypercalcemia of malignancy?
Loop diuretics: furosemide
What are the supposed advantages of torsemide over furosemide as a loop diuretic?
Torsemide has longer and smoother diuretic action and is less prone to diuretic resistance
What is the basis for the most common cause of urinary incontinence in the spayed bitch?
Most common reason for incontinence in the dog is hormone-responsive urinary incontinence in the spayed bitch
What are 2 drugs that treat hormone-responsive urinary incontinence?
Estrogens (estriol, Incurin)
Phenylpropanolamine (Proin)
How do estrogens work when treating hormone-responsive urinary incontinence?
Upregulates alpha receptors in the internal urethral sphincter
Loading doses given daily 1-2 weeks then tapered to lowest dose controlling signs
How does phenylpropanolamine work when treating hormone-responsive urinary incontinence?
Alpha agonist acting on internal urethral sphincter
Given orally 1-3 times daily
What do the terms “upper motor neuron bladder” and “reflex dysnergia” describe relative to urethral tone and bladder contraction?
Decrease urethral sphincter tone
Causes the detrusor muscle of the bladder to contract
What drugs do we give, and on what receptors do they act, to relax the internal versus external urethral sphincters?
Internal sphincter:
Prazosin or phenoxybenzaomine orally as an alpha-1 receptor antagonist
Acepromazine is also effective
External sphincter:
Diazepam or other benzodiazepine
How does bethanechol act to stimulate the bladder detrusor muscle?
Bethancehol causes the detrusor muscle to contract as it is a muscarinic agonist
What side effects are seen with bethanechol?
This drug affects the GI tract, salivation and defecation are common
How would you treat an accidnetal overdose of bethanechol?
When treating an overdose, you can give atropine to reverse it
Atropine is a muscarinic antagonist
Why does chronic overstretching of the bladder impact its ability to contract?
The impulse that causes contraction of the bladder spreads through the tight junctions of the detrusor muscle. If you overstretch the muscle, the tight junctions are in apposition and the impulses don’t propagate as they normally should
What is oxybutynin used for?
It is an anticholinergic agent with most of its effects on the bladder as a smooth muscle antispasmodic and it may have some local anesthetic effect
It is used in humans to treat symptoms of urge incontinence, urgency, and frequency arising from the overactive bladder
For what purpose is phenazopyridine used in humans and why is seldom used in dogs or cats?
It is an oral azo dye that is excreted in the urine having an analgesic effect in humans
It has a low therapeutic index in dogs and cats
—Cats: high risk of Heinz body anemia and methemoglobinemia
—Dogs: extremely high incidence of KCS suspected
How is fluid therapy used to manage acute oliguric renal failure?
The first step is to volume load when warranted
After rehydration, attempts can be made to increase urine production by fluid diuresis at about 6-8 ml/kg over a 4 hour period
If this is not successful, this therapy should be stopped to avoid overhydration
Which diuretics may be of use when managing acute oliguric renal failure and how do they work?
Mannitol: should be infused at 0.5-1 g/kg IV over 20 minutes
If there is good urine production after one bolus, this can be repeated up to 4 times, but it anuria persists, hypovolemia and osmotic kidney damage may develop and so additional doses should not be given
Furosemide: must undergo glomerular filtration to work, which restricts its impact on anuria. However, it is commonly used at high doses, often as CRI
How do you improve renal perfusion other than fluid therapy when managing acute oliguric renal failure?
Dopamine agonist will help perfuse the renal artery
Use dopamine or fenoldopam
How do you manage hyperkalemia when managing acute oliguric renal failure?
Volume loading to dilute high potassium Drive potassium back into the cell ---Sodium bicarbonate to correct acidosis ---IV dextrose ---Insulin with dextrose
What are the dietary modifications for managing chronic renal failure?
Lower protein, phosphorus, and sodium
Increased potassium, omega-3 fatty acids, B vitamins and fat content, and are alkalinizing
Most effective treatment in CKF/CRF to manage signs and improve survival
What is the proposed mechanism for benefit of the nutraceuticals AminVast and Azodyl?
AminAvast: proprietary combination of amino acids and peptides said to slow kidney injury
Azodyl: “enteric dialysis” aimed at reducing azotemia by selecting for bacteria that promote intraluminal nitrogen utilization and reduce colonic absorption
What evidence supports AminVast?
It is hard to do research on this because it is proprietary (won’t tell you what is in it)
What evidence supports Azodyl?
Evidence shows that it fails to alter azotemia in cats with chronic kidney disease when sprinkled onto food
What is the fluid therapy used when managing chronic renal failure?
Subcutaneous fluid therapy to treat chronic dehydration, especially in cats
Owners can give SQ fluids at home on a regular basis to prevent this cycle
How do you manage hypertension from chronic renal failure?
Cat: amlodipine +/- ACE inhibitor
Dog: Ace inhibitor +/- amlodipine
How do you manage proteinuria from chronic renal failure?
Benazepril
How do you manage hyperphosphatemia from chronic renal failure?
Phosphate binding agents are added to the food:
Aluminum hydroxide
How do you manage Hypocalcemia from chronic renal failure?
Give calcitriol as the active form on an empty stomach to help raise calcium
How do you manage anemia from chronic renal failure?
Recombinant human erythropoietin to supplement EPO
- –Epopoetin (origina)
- –Darbepoietin (longer half-life, less antigenic)
Iron supplementation
Parenteral iron dextran IM
Oral iron supplements
What are the associated risks with parenteral iron dextran IM?
High incidence of anaphylactoid reactions
Risk of iron overload
What are the associated risks with oral iron supplements?
Tend to be safer, but can cause GI problems in some animals
How do you manage acidosis from chronic renal failure?
A renal diet provides some alkalinization, additional therapy may be needed
Sodium bicarbonate oral
Potassium citrate (also provides K)
How do you manage hypokalemia from chronic renal failure?
Oral supplements potassium gluconate or potassium citrate is commonly used
Degree of IV potassium supplementation is based on individual severity
—Standard dogma is IV K should be infused no faster than 0.5 mEq/kg/hr
How do you manage uremic gastroenteritis from chronic renal failure?
Use antiemetic and gastric protectants
