Micturition Disorders Flashcards
What is the normal residual volume?
< 0.2 - 0.5 mL/kg
What normally occurs during the storage phase of micturition?
- SNS pathway causes increased urethral tone and relaxation of detrusor muscle to allow filling and prevent urination
What normally occurs during the voiding phase of micturition?
- PNS pathway causes Ach release from pelvic nerve to contract detrusor muscle and relax urethral sphincter to allow urination
What is the drug of choice for promoting voiding by increasing detrusor muscle activity?
Bethanechol
What is the drug of choice to increase the tone of the urethral sphincters and promote urinary storage and filling phase of micturition?
Phenylpropanolamine (PPA) (Proin)
(to help with urinary leakage and incontinence)
What is the drug of choice to decrease the tone of the urethral sphincters and promote voiding and urination?
- Prazosin
- Phenoxybenzamine
- Tamsulosin
(Skeletal muscle relaxants like Diazepam IV, Aceprom and methocarbamol help too)
What clinical signs can be seen with an UMN bladder?
- Firm, distended bladder that is difficult to express
- CS of urinary retention!!
- History of IVDD, spinal trauma, neoplasia, FCE (lesions cranial to S1-S3)
What is the treatment protocol for a patient presenting with signs consistent with an UMN bladder?
- Reduce urethral tone with Prazosin or Phenoxybenzamine
- Stimulate bladder contractility with Bethanechol
- Treat underlying cause (ex: spinal cord lesion)
What is the treatment protocol for a patient presenting with signs consistent with an LMN bladder?
Increase urethral sphincter tone with Phenylpropanolamine (PPA / Proin)
What clinical signs can be seen with a LMN bladder?
- Flaccid bladder that is easily expressed
- Tail paralysis
- Loss of sensation to perineum
- Fecal incontinence
- Seen with lesions affecting S1-S3
What is detrusor urethral dyssynergy?
- Incoordination between detrusor muscle contraction and sphincter relaxation
- Results in an interruption in urine stream during peeing and incomplete voiding
What clinical signs can be seen with Detrusor urethral dyssynergy?
- Normal initiation of urination followed by a stop in urine stream
- Results in incomplete voiding followed by dribbling
- Seen in middle aged, large breed males
(Note: these patients have normal sacral reflexes and bladder tone, no nerve deficits)
How can Detrusor urethral dyssynergy be diagnosed?
- Measure residual urine volume!! Dyssynergy if > 20 mL/kg
- Presumptive diagnosis made based on interrupted urine pattern, large residual urine volume, and easy passage of catheter
What is the treatment plan for a dog with Detrusor urethral dyssynergy?
- Reduce urethral tone with Prazosin, Phenoxybenzamine, or Tamsulosin
What is USMI?
Urethral sphincter mechanism incompetence
What signmalment in dogs is a risk factor for Urethral sphincter mechanism incompetence (USMI)?
- Large breed spayed females (Due to lack of Estrogen which is normally protective)
- Dobermans , Schnauzers, Sheepdogs, Rotties, Boxers
- Increased risk if spayed < 3 months old or after 1st heat
- History of hooded vulva
- Short urethra (females)
- Obesity
List non neurogenic disorders of micturition resulting in an inability to store urine
- USMI
- Ectopic ureters
- Detrusor hyperreflexia (cystitis)
List non neurogenic disorders of micturition resulting in an inability to completely void urine
- Obstructive FIC (urethral plugs, stones, etc)
- Detrusor muscle atony from over distention
What history and presenting complaints do patients with USMI come in with?
- Incontinence when animal is relaxed, asleep, or after exertion
- Increased grooming
What is the treatment protocol for a female dog with USMI?
- Synthetic Estrogen: DES or Estriol (Incurin)
- PPA / Proin to increase sphincter tone and decrease incontinence
(Beware of BM toxicity with estrogen!!)
What is the treatment protocol for a male dog with USMI?
- Testosterone IM for 4-6 weeks
- Can also use PPA / proin to increase sphincter tone and decrease incontinence
What signalment can be consistent with ectopic ureters?
- YOUNG females < 1 yr old
- Golden Retrievers
- History of leaking urine without conscious awareness
A 4 year old female spayed dog is presenting after the owner found the dog this morning sleeping in a puddle of pee on her bed. The owner notes she urinates normally throughout the day. What do you suspect and how do you treat?
Suspect USMI treat with Phenylpropanolamine (PPA / Proin)
What dog breeds are predisposed to ectopic ureters?
- Golden retrievers
- Huskies
- Labs
(Young dogs!! < 1 yr old)