Problem Based Approach to UT Abnormalities in LA Flashcards
define pathologic polydipsia in large animals
more than 100 ml/kg/day
2x maintenance
could looks like 50-60L/day
13-16 gallons
or
>3 20L buckets per day
describe water balance in the brain
- thirst results from hypertonicity [serum Na+] and results in ADH release from supraoptic nuclei in hypothalamus with the goal of conserving water
- ADH prevents diuresis
- kidneys: maintain plasma osmolarity and water balance
-macula densa senses reduced GFR and triggers RAAS, resulting in formation and release of angiotensin II which causes ADH release from brain
-collecting ducts: AQUAPORINS inserted in response to ADH
-CONSERVE WATER
what are physiologic causes of polyruria and polydipsia in large animals?
polydipsia: lactation, hot weather, sweating, salt consumption
polyuria: iatrogenic (alpha-2), diuretic, corticosteroids, glucose, IVFT
where do the mechanisms for polyuria/polydipsia come from?
brain:
-psychogenic: bored and drink bc nothing else to do (common cause! esp in pigs)
-neurogenic: lack of ADH/vasopressin release
kidney:
-CKD
-nephrogenic diabetes insipidus (lack of response to ADH/vasopressin
other illness/systemic disease: most common!
-pituitary pars intermedia dysfunction!! (common cause, esp in older horses!)
-endotoxemia
describe the diagnostic approach to PU/PD
- confirm PU/PD: measure urine output or water intake
- if signs of hypertrichosis: PPID
- if increases serum creatinine and isosthenuria: CKD
- if hyposthenuric: figure out if psychogenic or truly nephrogenic diabetes insipidus
-look at USG after water deprivation
-if become well concentrated = psychogenic
-if USG still hyposth = DI; need to figure out if neurogenic or nephrogenic by measuring vasopressin levels in patient or response to exogenous vasopressin
-if vasopressin increases when dehydrated, is not neurogenic!
what is the difference between water deprivation and modified water deprivation test?
- water deprivation: restrict water for 24 hours, measure sCr and USG every 6 hours
-usually true DI horses will get dehydrated by 12 hours - modified: reduce water intake to 40ml/kg/day, offer small amount every 4 hours, monitor
-a little safer, can continue test for up to 3 days
both: signs of dehydration: USG >1.020
describe management for common PU/PD diseases
- psychogenic: water restriction, slow feeder, reduce boredom
- PPID (>15 years of age): pergolide mesylate (prascend)
- CKD: see previous lectures
- neurogenic DI/central DI: desmopressin acetate (V2 receptors on collecting tubules)
-exogenous compound to minic ADH/vasopressin - nephrogenic DI: no medication
when the problem is dysuria/stranguria, what part of UT is the issue?
LUT! urethra or bladder
can indicate: pain, infection, inflam, partial obstruction
can be congenital (urachal diverticulum) or acquired (urinary sediment, clot, stone, patent urachus)
what are ascending infection risk factors?
can result in urethritis, cystitis, ureteritis, pyelonephritis
- female (shorter urethra)
- breach of mucosa
- abnormal flow of urine: obstruction, abnormal bladder function, dehydration
- abnormal vulvar conformation
- catheterization
- contagious: pathogenic bacteria (corynebacterium renale)
- alkaline urine
describe corynebacterium renale
- gram +; affects males and females
- genitourinary tract infection!!
- enzootic posthitis (foreskin inflam), cystitis, and/or pyelonephritis
- CONTAGIOUS
- alkaline urine enhances bacterial adherence and pili function
- virulence factors: ureolysis and ammonium production to enhance colonizations of the epithelium
- infection results in a serum antibody response which is rarely curative and NOT protective
- treatment: urinary acidification and antibiotics
-beta lactam penicillins are the prototype!!
describe pyelonephritis hematogeneous route of infection
UNCOMMON; signs of systemic infection as opposed to dysuria/stranguria; most commonly seen in small ruminants post sx for urolithiasis
- bacteremia:
-neonatal sepsis
-actinobacillus
-colitis
-mastitis
-liver failure - septic embolic disease: infective endocarditis
compare and contrast features of upper (pyelonephritis) versus lower (cystitis) UT infection in large animals
incidence:
pyelo: uncommon!! uni > bilateral
cyst: infrequent relative to small animal
clin signs:
pyelo: colic, reduced appetite, pain on palpation per rectum
cyst: dysuria/stranguria, eating and drinking normally
fever:
pyelo: YES
cyst: no
CBC/fibrinogen:
pyelo: abnornal
cyst: normal
urine sediment
both abnormal
urine culture: indicated for both
diagnostic imaging:
pyelo: renal ultrasound, endoscopy
cyst: yes to determine predisposing causes
treatment:
antimicrobials, supportive care, trimethoprim-sulfamethoxazole for both
prognosis:
-pyelo: fair to good
cysto: excellent to poor dependent on underlying cause
describe nephrectomies in large animals
indications:
-unable to achieve medical cure
-(nephroliths can be impossible to cure)
describe treatment/management for urinary tract infections
- address predisposing factors whenever possibke
- appropriate antimicrobial medications
-stewardship, C/S, drugs with renal excretion will exceed plasma concentrations!
-treat through resolution of clinical signs, normal UA, repeat culture for pyelonephritis cases (10-14 days post finish treatment) - pain management:
-NSAIDs with care (until stranguria and dysuria improve)
-phenazopyridine: topical bladder anesthetic; give orally, kidneys excrete into urine, causes local anesthesia of bladder epithelium
describe incontinence
functional: bladder dysfunction
-neurogenic
-traumatic
-idiopathic: sabulous (sandy/gritty) cystitis
-toxic
structural:
-congenital: ectopic ureter (uncommon)
-prior surgery: marsupialization in goat
-neonate with patent urachus: dribble urine from urachus
describe localization of incontinence
UMN bladder (lesion S1 or rostral)
-UNCOMMON, will not have without other SEVERE neuro signs
-clinical syndrome: short spurts of urine, spastic bladder, turgid, distended bladder, difficult to express (EUS retains tone), overtime becomes atonic
-Ddx: EHV-1 myeloencephalitis (EHM), EPM, CVSM, trauma (C1-C, T3-S1)
LMN bladder (lesion S2-S4)
-most common
-clinical syndrome: continuous urine dribbling, +/- reduced perineal reflex, bladder paralysis, large flaccid bladder, easily expressed, decreased tone to urethra
-Ddx: polyneuritis equi/cauda equina syndrome, EHM, EPM, idiopathic bladder paralysis (most common reason!!), sacral trauma
KEY: with a neurogenic bladder expect to have other neuro deficits
describe diagnostic approach to incontinence (6)
- minimum database
-expect to see: not many abnormalities unless infectious (usually normal) - neuro exam +/- musculoskeletal exam
-+/- lumbosacral spinal tap even if bladder paralysis is the only abnormality
-MAY be reluctant to get into urination stance/posture if back pain or other (especially since males > females for idiopathic bladder paralysis) - rectal palpation: how distended and large is bladder, some info about bladder wall thickness
-long standing paralysis = inflammation. and irritation (feels like sandbag) - ultrasonography of urinary tract (kidneys)
- bladder endoscopy/cystoscopy: anatomical abnormalities or just inflamed from not voiding completely?
- urinalysis and culture
describe treatment and management of cystitis
stagnant urine, sediment, mucoprotein, and bladder mucosal damage can result in an established bacterial infection (ascending route) and inability to empty the bladder = risk of recurrence
short term management strategy: bladder mucosal healing!
1. frequent urinary catheterization, lavage to remove the debris
2. local and systemic anti-inflammatory
3. systemic antibiotics
describe prognosis of incontinence
- guarded for idiopathic bladder paralysis
- fair for return of function with treatable neurologic disease (EHM or EPM)
- palliative care
- can be managed for months (rarely years)
