Food Animal Urolithiasis Flashcards
What large animals have a higher incidence of urolithiasis? In wgat species is it rare?
goats and sheep +/- horses, pigs, cattle
South American camelids and Old-World camels
What is the pathogenesis of urolithiasis in food animals like?
- nutritional disease (mineral imbalances, altered water intake) causes the production of alkaline urine
- this results in the formation of supersaturated urine, which acts as a matrix for crystal precipitation
What are 5 objects in supersaturated urine that act as a matrix for crystal precipitation?
- debris
- casts
- cells
- bacteria
- mucoproteins
What are 3 causes of mucoprotein increase in the urine of food animals?
- estrogen
- low vitamin A
- high concentrate feed
What are the 5 most common types of uroliths in food animals?
- magnesium ammonium phosphate (struvite)
- calcium hydrogen phosphate
- calcium carbonate
- calcium oxalate
- silicate
What are the 2 classes of phosphatic calculi in food animal urine?
- struvite (magnesium ammonium phosphate)
- apatite (calcium phosphate)
What are 2 dietary risk factors that causes the development of phosphatic calculi? How?
- high concentrate - increased P and Mg, low Ca increases pH and P absorption and excretion
- low roughage - decreased salivation and GIT P loss results in increased urinary excretion
What are the 2 major dietary risks for the development of calcium carbonate uroliths? What may also play a role?
- high calcium diets
- clover and alfalfa - high in Ca and oxalate, low in P and Mg
water hardness
Although it is unclear what factors influence the formation of calcium oxalate uroliths, what has been hypothesized to contribute?
- low solubility of urine
- oxalate containing plants
Oxalate is normal to find in the urine. Why?
result of glycine and ascorbic acid metabolism
What is the typical presentation of silicate calculi? What causes its formation? Where is this especially common?
singular stones
ration with high Ca:P ratios (2.8:1) —> grasses of western North America and Canada
What is not correlated to the development of silicate calculi?
urine pH
What gender has higher incidence of urolithiasis? Why? What are the 4 most common sites of obstruction?
males —> smaller, longer urethra
- urethral process
- sigmoid flexure
- ischial arch
- bladder neck
What history is especially important to collect when diagnosing urolthiasis?
- diet - low roughage, high concentrate (common in feedlot cattle!)
- premature castration - hypoplastic urethra = smaller lumen
- purpose
- urination history
What are some common behaviors indicative of pain or discomfort caused by urolithiasis?
- depression
- vocalization
- bruxism - grinding teeth
- tail flagging - erect, quivering
- stranguria, pollakiuria, dysuria
What are important aspects of the physical exam in cases of urolithiasis?
- TPR - tachycardia, pyrexia with urethral rupture
- abdominal distention and contour - uroabdomen, ruminal stasis
- abdomen palpation - fluid ballottement, distended bladder, “water belly” of SQ urine
What is the abdomen of this goat like?
normal!
- fat pad common in the inguinal area, does not extend up to the abdomen
What is the abdominal contour of the goat and calf like?
swollen around prepuce and inguinal area —> uroabdomen
- more extended than the normal goat fat pad
What is the abdominal contour of the sheep and cow like?
SQ swelling and edema —> water belly
What is the abdominal contour of this sheep like?
ventral/para-sheath edema
- not uroabdomen, extends too far cranial
What can be observed in the perineal area indicative of urolthiasis?
urethral pulse seen ventral to the anus due to increased pressure —> not in sync with HR
How are the bladder, peritoneum, and kidneys affected by urolithiasis on ultrasound?
distended —> can do transabdominal in small ruminants, must be transrectal in cattle
hypo/anechoic fluid in abdomen
hydronephrosis = dilated renal pelvis (chronic)
What views are preferred for radiographing the urinary system for diagnosing urolithiasis? Which uroliths can be seen?
two LM views with legs cranial and caudal —> need to catch all of the urethra in males, can observe location and number
calcium oxalate and calcium carbonate
What are 4 things seen on serum biochemistry indicative of urolithiasis?
- azotemia - BUN (> 30 mg/dL), CREA (> 3 mg/dL)
- electrolytes - high K, low Na and Cl
- hemoconcentration
- hyperlactatemia