Changes

==Introduction==

==Introduction==

Urolithiasis is the main cause of obstruction in the lower urinary tract.  Although it occurs in both males and females, urolithiasis is '''more common in males''' due to their long, narrow urethra.

Urolithiasis is the main cause of obstruction in the lower urinary tract.  Although it occurs in both males and females, urolithiasis is '''more common in mammalian males''' due to their long, narrow urethra.

Common sites of obstruction in the different species include:

Common sites of obstruction in the different species include:

In '''birds''', the condition arises during breeding or following egg incubation. Some birds sit very tight on their eggs and fail to void their cloacal contents regularly. Urates can precipitate in the cloaca and lead to the formation of a urolith.

In '''birds''', the condition arises during breeding or following egg incubation. Some birds sit very tight on their eggs and fail to void their cloacal contents regularly. Urates can precipitate in the cloaca and lead to the formation of a urolith.

===Types of uroliths===

 

===Types of Uroliths===

'''Struvite'''  

'''Struvite'''  

most common urolith in small animals

:most common urolith in small animals commonly associated with infection by urease producing organisms such as [[:Category:Staphylococcus species|''Staphylococcus'']] or ''[[Proteus]]''

 

:more common in females due to increased susceptibility to urinary tract infections

commonly associated with infection by urease producing organisms such as ''Staphylococcus'' or ''Proteus''

:formation enhanced by the presence of alkaline urine

 

more common in females due to increased susceptibility to urinary tract infections

 

formation enhanced by the presence of alkaline urine

'''Calcium oxalate'''

'''Calcium oxalate'''

form due to supersaturation of urine with calcium

:form due to supersaturation of urine with calcium

 

:often have spine-like projections

often have spine-like projections

'''Urate'''

'''Urate'''

Dalmations predisposed, urolith of birds

:Dalmations predisposed, urolith of birds

'''Cystine'''

'''Cystine'''

occurs with cystinuria

:occurs with cystinuria

'''Calcium carbonate'''

'''Calcium carbonate'''

occurs in horses

:occurs in horses

'''Silica'''

'''Silica'''

occurs in pastured ruminants

:occurs in pastured ruminants, development may be related to diet

 

development may be related to diet

==Clinical signs==

==Clinical Signs==

Clinical signs are due to the macroscopic uroliths in the lower urinary tract which interfere with the flow of urine or irritate the mucosal lining. This leads to signs such as: '''dysuria, stranguria and haematuria'''.

Clinical signs are due to the macroscopic uroliths in the lower urinary tract which interfere with the flow of urine or irritate the mucosal lining. This leads to signs such as: '''dysuria, stranguria and haematuria'''.

'''Nephroliths''' are often asymptomatic unless pyelonephritis develops or the stone passes into the ureter.

'''Nephroliths''' are often asymptomatic unless [[pyelonephritis]] develops or the stone passes into the ureter.

'''Ureteroliths''' may present as pain which is difficult to detect, or signs of vomiting, lethary, especially if there is distension of the renal capsule and developing hydronephrosis. Clinical signs may not be apparent unless both ureters are affected, there is contralateral chronic kidney disease, or a renal infection develops.

'''Ureteroliths''' may present as pain which is difficult to detect, or signs of vomiting, lethargy, especially if there is distension of the renal capsule and developing [[hydronephrosis]]. Clinical signs may not be apparent unless both ureters are affected, there is contralateral chronic kidney disease, or a renal infection develops.

'''Urethral obstruction''' may occur suddenly or may develop over days or weeks. There will be dysuria and stranguria, and complete obstruction leads to: depression, anorexia, vomiting, dehydration, coma and death.

'''Urethral obstruction''' may occur suddenly or may develop over days or weeks. There will be dysuria and stranguria, and complete obstruction leads to: depression, anorexia, vomiting, dehydration, coma and death.

'''Contrast studies''' include: excretory urogram for nephroliths and ureteroliths, double contrast radiography for bladder stones, retrograde urethrogram for urethroliths.

'''Contrast studies''' include: excretory urogram for nephroliths and ureteroliths, double contrast radiography for bladder stones, retrograde urethrogram for urethroliths.

'''Urinalysis''', including examination of urine, '''urine culture and sensitivity''' and cristal identification on microscopic exmination, is also indicated.

'''Urinalysis''', including examination of urine, '''urine culture and sensitivity''' and crystal identification on microscopic examination, is also indicated.

Urethral obstruction is diagnosed by palpating a distended, hard and painful bladder.

Urethral obstruction is diagnosed by palpating a distended, hard and painful bladder.

Syme, H. (2009) '''Urogenital system: urolithiasis''' ''RVC student notes''

Syme, H. (2009) '''Urogenital system: urolithiasis''' ''RVC student notes''

[[Category:Lower Urinary Tract - Pathology]]

[[Category:Lower Urinary Tract - Pathology]]

[[Category:To Do - Urinary]]

[[Category:Urological Diseases - Birds]]