Urinary tract disease

John Chitty

doi:10.22233/9781910443903.17

British Small Animal Veterinary Association , e21 (2026); https://doi.org/10.22233/9781910443903.17

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Urinary tract disease

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Author: John Chitty
From: BSAVA Manual of Guinea Pigs
Item: Chapter 17, pp 205 - 215
DOI: 10.22233/9781910443903.17
Copyright: © 2026 British Small Animal Veterinary Association
Publication Date: January 2026

Urinary tract disease is common in guinea pigs. Much of this disease affects the lower urinary tract, but renal disease also occurs and may well be underdiagnosed, as it can be difficult to diagnose. This chapter will equip the reader to approach a range of bladder and kidney diseases in guinea pigs with confidence.

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Figures

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17.1

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17.1 Urinary tract anatomy of the sow Drawn by S.J. Elmhurst BA Hons (www.livingart.org.uk) and reproduced with her permission.

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17.2

Nephrosclerosis identified by post-mortem examination in two guinea pigs. In (a) the changes were considered incidental (the animal died of heart failure) and in (b) they were considered significant; clinical signs in this animal included weight loss and oedema. The pre-mortem plasma creatinine concentrations were not increased, presumably as a result of muscle loss, although plasma urea concentrations were increased (© John Chitty) © 2026 British Small Animal Veterinary Association

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17.2 Nephrosclerosis identified by post-mortem examination in two guinea pigs. In (a) the changes were considered incidental (the animal died of heart failure) and in (b) they were considered significant; clinical signs in this animal included weight loss and oedema. The pre-mortem plasma creatinine concentrations were not increased, presumably as a result of muscle loss, although plasma urea concentrations were increased (© John Chitty)

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17.3

Radiographs of normal kidneys (arrowed) in guinea pigs. (a) The kidneys are visible, although it should be noted that they can be difficult to visualize in overweight guinea pigs. (b) The kidneys are easier to identify in an animal with gas-filled viscera (in this case, gastric dilatation and rotation). (c) In this animal, the kidneys are slightly smaller and their outlines are not smooth (© John Chitty) © 2026 British Small Animal Veterinary Association

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17.3 Radiographs of normal kidneys (arrowed) in guinea pigs. (a) The kidneys are visible, although it should be noted that they can be difficult to visualize in overweight guinea pigs. (b) The kidneys are easier to identify in an animal with gas-filled viscera (in this case, gastric dilatation and rotation). (c) In this animal, the kidneys are slightly smaller and their outlines are not smooth (© John Chitty)

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17.4

Computed tomographic images of (a, b) normal and (c) diseased kidneys (arrowed). (a, b) The renal cortex and pelvis can be identified, as can the shape and size of the kidneys. (c) Calcified regions can be identified throughout the cortices and the surface of each kidney is irregular (© John Chitty) © 2026 British Small Animal Veterinary Association

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17.4 Computed tomographic images of (a, b) normal and (c) diseased kidneys (arrowed). (a, b) The renal cortex and pelvis can be identified, as can the shape and size of the kidneys. (c) Calcified regions can be identified throughout the cortices and the surface of each kidney is irregular (© John Chitty)

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17.5

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17.5 A calcium oxalate urolith and proteinaceous calcified ‘sludge’ removed together during cystotomy (© John Chitty)

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17.6

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17.6 Urine produced by a guinea pig with haematuria (© John Chitty)

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17.7

Normal urine voided by a guinea pig in an anaesthetic chamber on induction of anaesthesia. The urine is cloudy due to the presence of crystals (© John Chitty) © 2026 British Small Animal Veterinary Association

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17.7 Normal urine voided by a guinea pig in an anaesthetic chamber on induction of anaesthesia. The urine is cloudy due to the presence of crystals (© John Chitty)

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17.8

(a) Lateral radiograph of a guinea pig showing calcified bladder contents and a thickened bladder wall. The callipers indicate the thickness of the bladder wall (0.65 cm). (b) Sludge and urolith formation (arrowed) and a thickened bladder wall are visible on this radiograph (© John Chitty) © 2026 British Small Animal Veterinary Association

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17.8 (a) Lateral radiograph of a guinea pig showing calcified bladder contents and a thickened bladder wall. The callipers indicate the thickness of the bladder wall (0.65 cm). (b) Sludge and urolith formation (arrowed) and a thickened bladder wall are visible on this radiograph (© John Chitty)

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17.9

Ultrasonographic images of bladder disease in guinea pigs. (a) The bladder wall has lost its smooth lining but is not thickened. Crystalluria is evident. (b) The bladder wall is slightly thickened and shows roughening of the lining. (c) Crystals coalescing to form a sludge. (d) A urolith is forming and the bladder wall is clearly thickened. (e) Sludging of urine associated with thickening of the bladder wall (© John Chitty) © 2026 British Small Animal Veterinary Association

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17.9 Ultrasonographic images of bladder disease in guinea pigs. (a) The bladder wall has lost its smooth lining but is not thickened. Crystalluria is evident. (b) The bladder wall is slightly thickened and shows roughening of the lining. (c) Crystals coalescing to form a sludge. (d) A urolith is forming and the bladder wall is clearly thickened. (e) Sludging of urine associated with thickening of the bladder wall (© John Chitty)

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17.10

Radiographic diagnosis of urolithiasis in guinea pigs. (a) Calcification of the bladder lining (white arrow) and nephrolith formation (red arrow). (b) A similar situation to that shown in (a) with calcification of the bladder lining (white arrow) and nephrolith formation (red arrow) evident. Note the gastrointestinal ileus (the reason for radiography); the uroliths were incidental findings. However, both the gastrointestinal and urinary signs in this animal probably resulted from an underlying inflammatory focus – in this case, advanced middle ear disease (not shown on this radiograph). (c) Bladder uroliths (white arrow) and nephroliths (red arrows). (di) Lateral and (dii) dorsoventral radiographs of the same animal, showing urolith formation in the bladder (white arrows), ureters (arrowheads) and kidneys (red arrows). (e) Multiple small stones in the bladder and ureter. (f) A single urolith is visible in this case, and the bladder wall is markedly thickened. The author would normally manage cases similar to these medically, as the rate of recurrence of uroliths is very high. Surgery would be indicated in cases where obstruction occurred or where bladder pain could not be controlled (© John Chitty) © 2026 British Small Animal Veterinary Association

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17.10 Radiographic diagnosis of urolithiasis in guinea pigs. (a) Calcification of the bladder lining (white arrow) and nephrolith formation (red arrow). (b) A similar situation to that shown in (a) with calcification of the bladder lining (white arrow) and nephrolith formation (red arrow) evident. Note the gastrointestinal ileus (the reason for radiography); the uroliths were incidental findings. However, both the gastrointestinal and urinary signs in this animal probably resulted from an underlying inflammatory focus – in this case, advanced middle ear disease (not shown on this radiograph). (c) Bladder uroliths (white arrow) and nephroliths (red arrows). (di) Lateral and (dii) dorsoventral radiographs of the same animal, showing urolith formation in the bladder (white arrows), ureters (arrowheads) and kidneys (red arrows). (e) Multiple small stones in the bladder and ureter. (f) A single urolith is visible in this case, and the bladder wall is markedly thickened. The author would normally manage cases similar to these medically, as the rate of recurrence of uroliths is very high. Surgery would be indicated in cases where obstruction occurred or where bladder pain could not be controlled (© John Chitty)

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17.11

Lateral radiograph of a guinea pig showing a large urolith associated with urinary obstruction. Calcified sludge with smaller stones is also present in the bladder. Radiographic changes in the distal lumbar spine are evident; these are likely to be the underlying cause of urinary stasis and will require management postoperatively (© John Chitty) © 2026 British Small Animal Veterinary Association

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17.11 Lateral radiograph of a guinea pig showing a large urolith associated with urinary obstruction. Calcified sludge with smaller stones is also present in the bladder. Radiographic changes in the distal lumbar spine are evident; these are likely to be the underlying cause of urinary stasis and will require management postoperatively (© John Chitty)

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17.12

Lateral radiograph of a guinea pig showing calcification of the bladder lining after a cystotomy (arrowed). This calcification formed within 1 month of the surgery in spite of the animal receiving fluid therapy, anti-inflammatory drugs and diuretics. The animal was already showing signs of cystitis at the time this radiograph was taken and a guarded prognosis was given (© John Chitty) © 2026 British Small Animal Veterinary Association

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17.12 Lateral radiograph of a guinea pig showing calcification of the bladder lining after a cystotomy (arrowed). This calcification formed within 1 month of the surgery in spite of the animal receiving fluid therapy, anti-inflammatory drugs and diuretics. The animal was already showing signs of cystitis at the time this radiograph was taken and a guarded prognosis was given (© John Chitty)

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17.13

Lateral radiograph showing a urolith in the distal urethra/clitoral fossa of a sow. A metal probe, inserted into the vagina for orientation, can also be seen (© John Chitty) © 2026 British Small Animal Veterinary Association

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17.13 Lateral radiograph showing a urolith in the distal urethra/clitoral fossa of a sow. A metal probe, inserted into the vagina for orientation, can also be seen (© John Chitty)

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17.14

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17.15

(a, b) Removal of a urethral stone that is too large to be manually expressed. An incision is made over the stone to allow it to be removed and the wound is left to heal by secondary intention (© John Chitty) © 2026 British Small Animal Veterinary Association

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17.15 (a, b) Removal of a urethral stone that is too large to be manually expressed. An incision is made over the stone to allow it to be removed and the wound is left to heal by secondary intention (© John Chitty)