Term
| What innervates the detrusor muscle? |
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Definition
Parasympathetics from pelvic nerve (S1-S3) contract detrusor.
Sympathetics from hypogastric nerve (L1-L4) synapsing in the caudal mesenteric ganglion supply the detrusor via beta 2 adrenergics, which cause bladder relaxation upon stimulation. |
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Term
| What innervates the internal urethral sphincter? |
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Definition
| Sympathetics (alpha 1 adrenergic): stimulation results in contraction, keeping sphincter closed. |
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Term
| What innervates the external urethral sphincter? |
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Definition
Sympathetics (alpha adrenergic) supply the striated muscle of the external sphincter, keeping it closed.
Somatic innervation comes from pudendal nerve (S1-S3): stimulation contracts. |
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Term
| What signs are associated with lower motor neuron lesions of the bladder? |
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Definition
Easy to express manually, reduced sphincter tone.
"Atonic bladder": loss of pelvic nerve or sacral spinal segments result in inability to contract detrusor.
Dribbling of urine with bladder remaining full ("overflow incontinence"). |
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Term
| What signs are associated with upper motor neuron lesions of the bladder? |
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Definition
Difficult to express manually, increased sphincter tone.
"Automatic bladder": results from nonvoluntary micturition when threshold bladder capacity is reached.
Reflexive destrusor contraction is incomplete and urethral sphincter is spastic, resulting in incomplete emptying. |
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Term
| How can you evaluate the pudendal nerve in an exam? |
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Definition
Perineal reflex.
Also bulbospongiosus reflex (squeezing distal penis or edges of vulva, should result in anal sphincter contraction) evaluates both pudendal and sacral spinal segments. |
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Term
| In a normal animal, what should be the maximum residual volume left in the bladder after micturition? |
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Definition
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Term
| What is detrusor-urethral dyssynergia? |
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Definition
| Initiation of detrusor reflex is followed by involuntary contraction of urethral sphincter (either smooth or striated - different conditions). Can result from lesions of the reticulospinal tract or caudal mesenteric ganglion. |
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Term
| Is hormone-responsive incontinence mainly a disorder of older or younger animals? Males or females? |
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Definition
| Older (mean age = 8 yrs). Has occurred in animals as young as 8 mos. Mainly spayed female dogs. |
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Term
| What is the main role of estrogens in urethral competence? |
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Definition
| Increased responsiveness to alpha adrenergics. |
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Term
| What characterizes "Urge Incontinence"? |
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Definition
| Detrusor hyperreflexia: involuntary detrusor contractions resulting in frequent voiding of small amounts of urine. Often associated with an inflamed bladder; sometimes with spinal tract/cerebellar problem. |
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Term
| What is detrusor atony from overdistension? |
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Definition
| Bladder overdistends due to a mechanical or functional (i.e. neurogenic) outflow obstruction. Tight junctions of detrusor muscle are separated. Subsequently, detrusor can no longer effectively contract. |
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Term
| What are ectopic ureters? |
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Definition
| Failure of ureters to open at trigone or tunneling through trigone to urethra (males and females), (or uterus, vagina in females). |
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Term
| What is the difference between intramural and extramural ectopic ureters? |
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Definition
| Intramural ectopic ureters tunnels between the muscularis and submucosa, and have zero, one, or more openings. Extramural ectopic ureters bypass the bladder and open at a distant site. |
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Term
| Signs of ectopic ureter(s): |
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Definition
Soaked perineal (female) or preputial (male) area.
Continuous or postural incontinence.
In females, discharge of urine into vestibulovaginal urethra, or incompetence of urethral sphincter, results in continuous incontinence. |
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Term
| What is a pelvic bladder? |
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Definition
| Neck of bladder is displaced caudally in pelvic canal (limits bladder distension) and urethra is shortened or displaced. Most often assoc. with incontinence in young, female, intact dogs. |
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Term
| What drugs are used to treat hormone-responsive incontinence? |
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Definition
Diethlystilbestrol or conjugated estrogen (Premarin) is used in females, and testosterone cypionate in males. These increase responsiveness to alpha 1 adrenergics.
Alpha agonists are also used to increase urethral tone. Phenylpropanolamine is first choice with alternate ephedrine. Contraindicated in animals with glaucoma, diabetes, hypertension.
Imipramine is an antidepressant which inhibits NE uptake; used in concert with sex hormones and/or alpha agonists. |
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Term
| What drugs are used to treat detrusor hyperspasticity? |
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Definition
| Anticholinergic drugs such as propantheline, flavoxate, oxybutynin, dicyclomine (more selective than atropine). Contraindicated with glaucoma, hyperthyroidism, cardiac dz, prostatic dz. |
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Term
| What drug can be used to treat detrusor atony? |
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Definition
| Cholinergic agent: bethanechol (more selective than methacholine, physostigmine). Contraindicated if urethral obstruction is present (duh!) |
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Term
| What drugs can be used to treat urethral spasticity? |
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Definition
| If due to smooth muscle (internal sphincter) hypertonicity, can use alpha adrenergic antagonist: phenoxybenzamine, prazosin, terazosin. If due to striated muscle hypertonicity (external sphincter), can use skeletal muscle relaxant (diazepam, dantrolene, baclofen). |
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Term
| What is an ACE inhibitor? |
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Definition
First-line therapy for arterial hypertension.
Angiotensin-converting enzyme (in the lungs) converts ATI to ATII...which then causes peripheral vasoconstriction and stimulates aldosterone release from the adrenal gland (which results in Na+ and water retention, increasing blood pressure and volume). So, ACE inhibitors prevent those effects and dilate efferent renal arterioles, decreasing glomerular (and systemic) blood pressure and thus proteinuria. |
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Term
| What drugs are ACE inhibitors? Side effects? |
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Definition
| Enalapril, benezapril. Can cause decreased renal perfusion, resulting in tubular necrosis and renal failure. Hyperkalemia possible. Vomiting, myelosuppression, seizures. |
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Term
| What are calcium channel blockers? |
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Definition
| Anti-hypertensive agents. Minimize renal damage by stopping Ca++ regulated catabolic and lysosomal enzyme systems (????) |
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Term
| What drugs are calcium channel blockers? |
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Definition
| Amlodipine, diltiazem, nefedipine. |
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Term
| How do adrenergic receptor antagonists work to treat hypertension? |
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Definition
Beta blockers (propanolol) stop renin release and reduce CO (which reflexively decreases peripheral resistance).
Alpha 1 blockers (prazosin) inhibit vasoconstriction by stopping the effect of alpha 1 stimulation on vasculature. |
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Term
| When can propanolol be used? |
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Definition
| To treat hypertension by blocking beta receptors. Should not be used in asthmatic cats (can induce bronchospasm). Can cause bradycardia, hyperkalemia, insulin resistance. |
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Term
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Definition
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Term
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Definition
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Term
| What drug can be used in a hypertensive crisis? |
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Definition
| Sodium nitroprusside relaxes both arteries and veins. Use only if closely monitoring blood pressure. |
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Term
| What conditions can be treated with the use of diuretics? |
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Definition
| pulmonary edema, ascites, hypertension, glaucoma, cerebral edema, oliguric/anuric renal failure. |
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Term
| How does an osmotic diuretic work? What are examples of osmotic diuretics? |
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Definition
| Filtered by glomerulus but not reabsorbed by the tubules, osmotic diuretics result in water being pulled into the filtrate (or prevented from leaving). Mannitol (25%), urea (30%), hypertonic dextrose can all be used. |
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Term
| How do xanthines work? Some examples? |
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Definition
| Inhibit tubular reabsorption of Na+ and Cl- and increase RBF. "Filtration diuretics." Theophylline, Aminophylline, Glucophylline. |
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Term
| How do carbonic anhydrase inhibitors work? An example drug? |
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Definition
| Reduces availability of H+ so increases excretion of Na+ and K+. Results in acidosis and hypokalemia. Acetazolamide. |
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Term
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Definition
| Inhibit reabsorption of Na+ and Cl- in distal tubule. Chlorthiazide, Hydrochlorothiazide. |
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Term
| How do loop diuretics work? Indications? Drug examples? |
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Definition
Inhibit Na+ and Cl- absorption by inhibiting Na/H/2Cl transporter at luminal membrane on thick ascending LOH.
Indicated for acute pulmonary edema, hypercalcemia (increases Ca++ excretion), cerebral edema. Furosemide, bumetanide. |
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Term
| Potassium-sparing diuretics: how do they work? |
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Definition
| Spironolactone and eplerenone are aldosterone antagonists (decrease Na+ absorption and K+ excretion). Triamterene and amiloride are not aldosterone-antagonists but spare K+. |
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Term
| What are some renoprotective agents? |
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Definition
Dopamine (increases RBF).
Fenoldopam is a DA-receptor agonist. |
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Term
| What drugs are used to treat bladder atony and spasticity? |
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Definition
| Cholinergic and anticholinergics, respectively. Detrusor is more under parasympathetic control than sympathetic. |
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Term
| Alpha agonists are indicated for which micturition disorder? |
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Definition
| Hormone-responsive incontinence (repro hormones increased responsiveness to alpha agonists). |
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Term
| Which category of drug is used to relax smooth muscle of the urethra? |
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Definition
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Term
| Which category of rug is most commonly-prescribed antihypertensive drug in dogs? |
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Definition
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Term
| Which category of rug is most commonly-prescribed antihypertensive drug in cats? |
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Definition
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Term
| What are the indications for diuretics? |
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Definition
| Hypertension, pulmonary edema, cerebral edema, glaucoma |
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Term
| What is the side effect to be most concerned with during prolonged therapy with thiazide or loop diuretics? |
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Definition
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Term
| Name a K+ sparing diuretic. |
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Definition
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Term
| How does renal insufficiency affect therapeutic approach to drug choice and dosage (generally)? |
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Definition
Avoid drugs metabolized or excreted unchanged by the kidney. Adjust dose or dosage interval according to:
Df = Dn/Cs or Tf = Tn x Cs where Cs is serum creatinine concentration. |
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