Final Exam - Urolithiasis

Question 1

what is required for crystals to deposit on?

Answer 1

nidus!!!!

Question 2

what urine type enhances stone formation? what stones specifically?

Answer 2

alkaline urine

carbonate & phosphate

Question 3

what is the pathophysiology of urolithiasis?

Answer 3

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

Question 4

what are some examples of things that can serve as a nidus for urolithiasis formation?

Answer 4

desquamated epithelial cells, necrotic tissues, precipitation of solutes, concretion of precipitated salts, & urinary mucoprotein

Question 5

what are some risk factors for urolithiasis?

Answer 5

high Ca:P ratio, high magnesium, low fiber, low urine output, alkaline urine, UTI, diets low in vitamin A, & high estrogen intake

Question 6

food animals fed alfalfa (hay, pellet feeds) are predisposed to what urolith type?

Answer 6

calcium carbonate stones

Question 7

what are the main types of uroliths seen in food animals?

Answer 7

struvite, apatite, calcium carbonate, silicate, & calcium oxalate

Question 8

what are some early signs associated with urolithiasis in food animals? what are some late signs?

Answer 8

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

Question 9

what are the number 1 & number 2 spots for where urolith obstructions occur?

Answer 9

1. urethral process
2. sigmoid flexure

Question 10

how does age at time of castration affect food animals later down the line with urolithiasis?

Answer 10

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

Question 11

what is the recommended time of castration for lambs & kids?

Answer 11

recommended to be done at 3 months or older

Question 12

what are the principles of therapy for food animals with urolithiasis?

Answer 12

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

Question 13

how do we relax the urethra in food animals?

Answer 13

can’t use prazosin (doesn’t work for these guys)

acepromazine, sedation, & appropriate analgesia can help!

Question 14

what is a treatment option for urolithiasis that is only useful for small ruminants? what happens if it doesn’t work?

Answer 14

urethral process amputation

if they don’t start peeing after amputation, they are still blocked!!!!!!

Question 15

what medical management is used for food animals with urolithiasis?

Answer 15

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!!!

Question 16

how are tube cystotomies used to correct urinary obstruction due to urolithiasis?

Answer 16

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!

Question 17

when is a cystotomy recommended for food animals with a urinary obstruction due to urolithiasis?

Answer 17

indicated for abdominal lavage & to repair a ruptured bladder - need to examine the bladder, remove stones, & catheterize them

Question 18

when is penile amputation used for urolithiasis?

Answer 18

on feedlots - penis is amputated & a stump is left tied to the skin

not a permanent solution

Question 19

how is a PU surgery done for food animals with urolithiasis? what is the prognosis?

Answer 19

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

Question 20

what is this? what is it used for? what are the advantages & disadvantages?

Answer 20

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!

Question 21

what is a better surgical option than a PU for obstructive urolithiasis in food animals? how is it done?

Answer 21

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

Question 22

what is bladder marsupialization? what are the risks of it?

Answer 22

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

Question 23

what food animal has the best prognosis if affected by urolithiasis?

Answer 23

intact young males with normal body conditions that present early in the disease course!!!

average is 40% survival to discharge, 50% with tube cystotomy

Question 24

T/F: recurrence of obstruction due to urolithiasis is guaranteed unless management changes are made

Answer 24

true

Question 25

how is urolithiasis prevented in food animals?

Answer 25

diet - decreased Ca:P ratio, decreased Mg in the diet, fiber content is increased, avoid grain, reduce concentrates in the diet, & encourage forage eating

increase urine output - temperature, palatability, & salt in the diet

pH - Cl containing ionic salts & acidifying feeds, but long term supplementation will wear off, so pulse therapy is indicated or given when pH is high (vitamin C is used for pigs to acidify the urine)