The anuric ram

Question 1

What is urolithiasis?

Answer 1

The presence of calculi, or uroliths, in the urinary tract.

Question 2

What can the clinical consequences be of urolithiasis?

Answer 2

Partial or complete urethral obstruction
Inability to pass urine 
Bladder distension and eventually rupture 
Abdominal pain 
Ulceration of the urethra or bladder
Cystitis 
Urethritis
Nephritis
Hydronephrosis
Severe azotaemia
Electrolyte imbalances
Hyperkalaemia due to reduce renal excretion
Death due to septicaemia from perforation of the bladder or urethra

Question 3

What are the most common sites of urolithiasis in the ram?

Answer 3

Vermiform appendage or urethral process

Sigmoid flexure

Question 4

What is the most common site for urolithiasis in the dog?

Answer 4

Base of the os penis

Question 5

What is the most common site for urolithiasis in the bull?

Answer 5

Sigmoid flexure or ischial arch

Question 6

What are the six different types of uroliths?

Answer 6

Struvite
Ureate 
Sillica
Calcium carbonate 
Calcium oxalate
Cysteine

Question 7

Why is urolithiasis more common in males than females?

Answer 7

Females do not have a sigmoid flexure of the ureter

Males have long, thin ureters whereas females have shorter, more stout urethras

Question 8

Why are castrated males more likely to develop urotlithiasis than entire males?

Answer 8

Castration causes the urethra to narrow

Question 9

What is the most common type of urolith found in ruminants?

Answer 9

Calcium oxalate, struvite, silica

Question 10

What is the most common type of urolith found in small animals?

Answer 10

Struvite

Question 11

What predisposes ruminants to developing uroliths?

Answer 11

High concentrate, low forage diet
Grazing in areas that have a high content of silica or oxalate
Diet with a low Ca:P ratio
Diet high in magnesium

Question 12

Why would an animal suffering with uroliths present with tachycardia and pyrexia?

Answer 12

Tachycardia:
Pain, infection, pyrexia

Pyrexia:
Infection

Question 13

How would you diagnose urolithiasis in the ram?

Answer 13

US perineum to try and determine location of obstruction
Abdominal palpation, feeling for distended bladder, hypersensitivity in the region of the sigmoid flexure, tender testes and over lumbar vertebra
Swelling around penis and surrounding tissues
Rectal (cattle) or abdominal palpation (sheep) finding a distended bladder or no bladder at all if bladder has burst
Uroperitoneum on abdominocentesis
US exam of the abdomen to reveal fluid filled abdomen if bladder has burst

Question 14

Struvite uroliths have the appearance of _____, whereas calcium carbonate and calcium oxalate are distinct _____ _____

Answer 14

Sand

Round stones

Question 15

Which uroliths are visible on radiographs?

Answer 15

Calcium carbonate

Calcium oxalate

Question 16

How could urolithiasis be treated?

Answer 16

Surgery to remove uroliths/blockages
US to break down crystals but mostly done in human medicine
Cystostomy tube
Correction of acid-base imbalance
Correction of dehydration
Treat ruminants with antispasmodics and muscle relaxants to promote relaxation of the retrator penis muscle to straighten the sigmoid flexure
Gentle manipulation and removal of uroliths from the urethral process in small ruminants
Perineal urethrostomy (making a new hole for the urethra in the perineum

Question 17

What is the most effective way to prevent formation of uroliths?

Answer 17

Alter diet so has a Ca:P ratio of at least 2:1
If on a high concentrate diet, ensure adequate Ca supplementation
Decrease urinary pH
Increase urinary excrection of Cl
Ensure adequate access to water
Give anionic supplement if small ruminant
Feed urinary diet (small animals)