Urinary stones (uroliths) are a common and painful problem in guinea pigs, often caused by excess dietary calcium. Signs include blood in urine, straining, and crying when urinating. Most cases require surgery, and identifying the problem early dramatically improves outcomes.
Last reviewed: June 2026
Why Guinea Pigs Get Urinary Stones
Guinea pigs are obligate herbivores with a unique calcium metabolism — they absorb dietary calcium indiscriminately from the gut, in contrast to most other mammals that regulate intestinal absorption to match needs. This means high-calcium diets rapidly produce hypercalciuria (excessive calcium in the urine) and calcium carbonate or calcium oxalate precipitates in the bladder or urethra. As described in Quesenberry & Carpenter's Ferrets, Rabbits and Rodents, urolithiasis is one of the most common reasons guinea pigs are presented for emergency care, and affected animals are often in significant pain by the time signs become apparent. The AEMV Pet Care Guides, 2024 recommend avoiding high-calcium vegetables as a primary preventive measure in all adult guinea pigs.
Signs of Urinary Stones
- Blood in urine (hematuria) — often bright red, or urine that stains pink on white bedding
- Straining to urinate, producing only drops or nothing
- Crying or vocalizing while attempting to urinate
- Hunched posture during and after urination
- Wet fur around the genital area and inner thighs
- Reduced or absent urine output
- Weight loss and reduced appetite as the pain becomes chronic
- Gritty white "sand" visible in dried urine spots on cage floor — calcium carbonate crystalluria
Female guinea pigs are affected more commonly than males, though male guinea pigs are at higher risk of urethral obstruction due to their narrower urethra, as described in Quesenberry & Carpenter.
Diagnosis and Treatment
Diagnosis is confirmed by abdominal x-rays, which readily reveal radiopaque calcium stones. Ultrasound helps assess the bladder wall and identify smaller stones. Blood work evaluates kidney function and calcium levels.
Treatment depends on stone size and location. Cystotomy (surgical removal of bladder stones) is the standard treatment for stones that cannot pass spontaneously. Small urethral plugs may be hydropulsed back into the bladder under anesthesia before surgical removal. Medical dissolution is generally not effective for calcium carbonate stones in guinea pigs. Post-operatively, dietary modification is essential to prevent recurrence — switching to lower-calcium vegetation dramatically reduces recurrence rates.
When to See a Vet
Call your vet today if:
- You notice blood in your guinea pig's urine
- Your guinea pig is straining to urinate or vocalizing during urination
- Fur around the genitals appears consistently wet
- You see white gritty deposits in the urine or on bedding
Go to the ER immediately if:
- Your guinea pig has produced no urine in 12 or more hours
- Your guinea pig is completely limp, cold, or unresponsive
- Straining is severe and continuous with obvious distress
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Frequently Asked Questions
What vegetables should guinea pigs avoid to prevent bladder stones?
Avoid or strictly limit high-calcium vegetables: kale, spinach, collard greens, parsley (high calcium despite high vitamin C), and dandelion greens in large quantities. Good lower-calcium daily vegetables include romaine lettuce, red leaf lettuce, cucumber, zucchini, and red bell pepper. Timothy hay (lower calcium than alfalfa hay) should be the dietary base for adult guinea pigs.
How much does guinea pig bladder stone surgery cost?
Exotic vet visit and x-rays typically cost $200–400. Cystotomy surgery under general anesthesia runs $600–1,500 at exotic-experienced facilities. Anesthesia in guinea pigs carries higher risk than in dogs/cats, contributing to overall cost. Post-operative monitoring and rechecks add $150–300. Total for uncomplicated surgery: $800–2,000.
Can urinary stones in guinea pigs be treated without surgery?
Surgery is almost always required for true bladder stones in guinea pigs. Very fine crystalline sludge (not discrete stones) may respond to dietary modification and increased water intake, but stones visible on x-ray need surgical removal. Delaying surgery allows stones to grow larger and worsens pain and kidney damage.
How can I get my guinea pig to drink more water to prevent stones?
Provide fresh, clean water daily in both a water bottle and a heavy ceramic bowl — some guinea pigs prefer bowls. Water intake increases naturally with higher fresh vegetable portions. Mild flavoring with a tiny amount of unsweetened juice is sometimes used but is not necessary if fresh vegetables are provided daily.
Can urinary stones come back after surgery?
Yes — recurrence is common without dietary change. Guinea pigs that return to a high-calcium diet after surgery frequently develop new stones within 12–24 months. Strict dietary management (low-calcium vegetables, unlimited timothy hay, fresh water) is the most effective long-term prevention strategy.
Still Not Sure if Your Guinea Pig Needs a Vet?
When you're not sure if this is wait-and-see or call-tonight, Voyage AI Vet triages in under 2 minutes. Describe what you're seeing in chat, share a photo of any blood in the urine or the urine spots on bedding, or a video of your guinea pig's urination attempts, or hop on a live video call if you want a second pair of eyes. Every answer comes with citations to the actual veterinary literature it's pulling from — so you see exactly where the guidance comes from, not just a chatbot's word.