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?
