Final Exam - Urolithiasis Flashcards
what is required for crystals to deposit on?
nidus!!!!
what urine type enhances stone formation? what stones specifically?
alkaline urine
carbonate & phosphate
what is the pathophysiology of urolithiasis?
ionized crystals become deposited around a nidus (desquamated epithelial cells, mucoproteins, etc)
urine is supersaturated with ionized minerals which exhausts the ability of urine crystallization inhibitors
alkaline urine enhances PO4 & CO3 stones - silicate polymers bind urine mucoproteins
what are some examples of things that can serve as a nidus for urolithiasis formation?
desquamated epithelial cells, necrotic tissues, precipitation of solutes, concretion of precipitated salts, & urinary mucoprotein
what are some risk factors for urolithiasis?
high Ca:P ratio, high magnesium, low fiber, low urine output, alkaline urine, UTI, diets low in vitamin A, & high estrogen intake
food animals fed alfalfa (hay, pellet feeds) are predisposed to what urolith type?
calcium carbonate stones
what are the main types of uroliths seen in food animals?
struvite, apatite, calcium carbonate, silicate, & calcium oxalate
what are some early signs associated with urolithiasis in food animals? what are some late signs?
early - anorexia, depression, bloat, restless, swishing tail, bruxism, stranguria, or anuria
late - recumbency, bradycardia, colic signs, vocalization, rectal prolapse, pendulous abdomen, ventral edema, & stranguria/anuria
what are the number 1 & number 2 spots for where urolith obstructions occur?
- urethral process
- sigmoid flexure
how does age at time of castration affect food animals later down the line with urolithiasis?
earlier castration makes a smaller urethra - especially in sheep
lambs, 5 months vs. 2 weeks = 3x wider if done at 5 months
kids - not as significant, but will be wider if older
what is the recommended time of castration for lambs & kids?
recommended to be done at 3 months or older
what are the principles of therapy for food animals with urolithiasis?
get them to pee & keep them peeing!!!
deal with the blockage -> relax the urethra -> flush the kidneys -> flush the urethra -> reduce chances of repeat occurrence
how do we relax the urethra in food animals?
can’t use prazosin (doesn’t work for these guys)
acepromazine, sedation, & appropriate analgesia can help!
what is a treatment option for urolithiasis that is only useful for small ruminants? what happens if it doesn’t work?
urethral process amputation
if they don’t start peeing after amputation, they are still blocked!!!!!!
what medical management is used for food animals with urolithiasis?
sedation, anti-spasmodics, & acidifying agents
walpole’s solution (sodium acetate, acetic acid, water) is infused into the bladder to acidify the urine with the hopes of unblocking - struvite only
cystocentesis can be used to administer walpole’s solution & to provide a temporary relief of pressure - this leaves a small defect in the lumen, so urine can leak if it continues to distend!!!
how are tube cystotomies used to correct urinary obstruction due to urolithiasis?
either placed laparoscopically or percutaneously - larger hole in bladder is formed, so an adhesion must form for us to remove it later in 10-14 days!
when is a cystotomy recommended for food animals with a urinary obstruction due to urolithiasis?
indicated for abdominal lavage & to repair a ruptured bladder - need to examine the bladder, remove stones, & catheterize them
when is penile amputation used for urolithiasis?
on feedlots - penis is amputated & a stump is left tied to the skin
not a permanent solution
how is a PU surgery done for food animals with urolithiasis? what is the prognosis?
urethra is split & sutured directly to the skin to create a stoma - allows them to urinate until the urethra strictures!!!
52% alive at 150 days post-op, MST is 46, stricture occurs
what is this? what is it used for? what are the advantages & disadvantages?
bonanno catheter
smaller diameter multi-species catheter that is used for obstructive urolithiasis
advantages - doesn’t require adhesion before pulling, works well for a few days, good for temporary stabilization & fluid therapy
disadvantages - can plug or slip out of the bladder, so you must think about where the bladder will rest in the body when it is empty!
what is a better surgical option than a PU for obstructive urolithiasis in food animals? how is it done?
vesicopreputial anastomosis - bladder is placed into the prepuce so that urine drains into the prepuce
mucosa to mucosa has less of a chance of stricture formation
prevents urine scald, so they won’t dribble as badly - better QOL
what is bladder marsupialization? what are the risks of it?
bladder is attached to the abdominal body wall
they will eventually get ascending cystitis leading to eventual pyelonephritis
they will leak urine all of the time, so there will be a lot of urine scald
what food animal has the best prognosis if affected by urolithiasis?
intact young males with normal body conditions that present early in the disease course!!!
average is 40% survival to discharge, 50% with tube cystotomy
T/F: recurrence of obstruction due to urolithiasis is guaranteed unless management changes are made
true
