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
