Micturition Disorders (Byron) Flashcards
the action of urinating
Micturition
What are the three major nerves involved in the neurologic control of micturition?
- Pudendal nerve (Somatic)
- Hypogastric nerve (Sympathetic)
- Pelvic nerve (Parasympathetic)
Neurologic Control of Micturition Storage:
Nicotinic cholinergic receptors stimulate skeletal muscle contraction in the urethra
Somatic: Pudendal nerve
Neurologic Control of Micturition Storage:
β-Receptors trigger detrusor relaxation
α-Receptors trigger urethral sphincter contraction
Sympathetic: Hypogastric nerve
Neurologic Control of Micturition Emptying:
Muscarinic cholinergic receptors trigger
detrusor contraction
Parasympathetic: Pelvic nerve
What are important factors for Continence?
- Smooth muscle of urethra
- Urethral mucosa - sealing
- Vasculature - possibly up to 30%
- Connective tissue - support
- Pelvic floor - Guarding reflex
What would be the most common urine storage disorder?
Urethral Sphincter Mechanism Incompetence (USMI)
(T/F) USMI is 7x more likely in large breed neutered females (> 15 kg)
True
The role of estrogen:
Low e2 leads to ____________ (increased/decreased) urethral muscle tone, urethral vascular atrophy, and glandular atrophy
decreased
What are some medical treatments for USMI?
- Alpha 1a Agonists (Phenylpropanolamine)
- can get hypertension - Estrogen Compounds
If the patient fails medical therapy for USMI, we move on to surgery such as:
- Artificial Urethral Sphincter
- Injectable Bulking Agents
- Incontinent since birth, before neutering
- Females more than males (maybe we aren’t seeing?)
- Incontinence may be intermittent or constant
- Breeds: Siberian Husky, Labrador, Golden Ret., Newfoundland, West Highland White Terrier, English Bulldog, Soft-Coated Wheaton Terrier, others
Ectopic Ureters
What is the most difficult urine storage disorder to diagnose in dogs, and why?
Detrusor Hyperreflexia (Instability), They can’t tell us they have an urgency
*Low compliance of the dutrusor muscle
*Contraction of the detrusor during the filling-phase of micturition
*May occur with USMI
*10% of poorly responsive incontinent dogs
Detrusor Hyperreflexia
A 6-year-old female spayed Labrador mix is brought to your clinic for ‘accidents’ in the house. The owner notes that they keep finding wet spots in the dog’s bed in the morning and she is licking her vulva more than normal. This has been going on for about 3 months and is now happening more often. The owner also suspects that the small drips they find on the floor are from the dog as well, since they have seen the dog drip urine once in the house.
While all information about the health of the dog is important, some points are most needed in this case. What key question is needed to determine if this dog has urinary incontinence (and likely USMI)?
Is the dog aware of it when she is dripping urine in the house?
(T/F) If a dog has a protein-losing nephropathy, hypertension is a real risk with that disease. Since the side effect of Phenylpropanolamine is hypertension, you will want to avoid it if possible
True
The treatment for Detrusor Hyperreflexia is to give:
Anticholinergic drugs
- Oxybutynin
- Imipramine
- Dicyclomine
The following clinical signs are related to what?:
*Straining to urinate
*Pain in urination
*Poor urine stream
*Inability to empty bladder
Disorders of Voiding
(T/F) Male dogs will have more problems related to storage disorders
False, more related with disorders of emptying
What must you do before diagnosing USMI in a male dog?
rule out DUD
Staining to Urinate
Mechanical Obstruction
* Calculi
* Stricture
* Neoplasia
Functional Obstruction
* Reflex Dyssinergia
We will see a _______________
Large Bladder
Straining to Urinate
Inflammation
*UTI
*Calculi
*Polypoid Cystitis
*Urethritis
*Neoplasia
We will see ______________
Small Bladder
Treatment options for DUD: α1-antagonists
* Non-specific α1-antagonist
* Hypotension risk (1st dose effect, start low)
* Q 8 h dosing
* Hypotension limits dose escalation
Prazosin
Treatment options for DUD: α1-antagonists
* Less effective than prazosin
* Hypotension risk
* Q 6 – 8 h dosing
* $$$
Phenoxybenzamine
Treatment options for DUD: α1-antagonists
* More urethra/ureter-specific α1-antagonist
* Less risk of hypotension
* Q 12 h dosing
* Very wide SAFETY MARGIN
Tamsulosin
Treatment options for DUD: Other smooth muscle relaxants
*Also anxiolytic
*Well tolerated
*Inexpensive
*Dose titration to effect
*Some risk of hypotension
Acepromazine
Treatment options for DUD: Skeletal muscle relaxants
*Most commonly used skeletal muscle relaxant
*Give 30 min before urinating
*Wide safety range
Diazepam
Treatment options for DUD: Anti-anxiety Rx
*Has smooth muscle relaxant properties
*Wide safety range
Acepromazine
Treatment options for DUD: Anti-anxiety Rx
*Fast acting
*Can add to acepromazine
Trazadone
Treatment options for DUD: Anti-anxiety Rx
*May take several weeks/months for full effect
*Do not stop suddenly (must taper)
Fluoxitine
Treatment Option: Overactive bladder (OAB)
- Anti-muscarinic and spasmolytic effects
Oxybutinin
