Answer: When the humans brought me in and the vet diagnosed me with a UTI, the conversation was more focused on treatment options going forward. However, you raise a good question, so we will do our best to answer it!
We should point out that there are actually a few similar, related urinary tract conditions that are relatively common problems for guinea pigs:
A Urinary Tract Infection (UTI) is when the urinary tract gets infected, most commonly by E. Coli, but sometimes from other viruses and fungi. For guinea pigs, the reason this usually happens is a combination of our short legs and contact with wet bedding and droppings.
Bladder stones are hard accumulations of calcium carbonate (90%+ of the time) or calcium oxalate that form in the bladder. Stones can be especially dangerous in male piggies because they can block the flow of urine more easily than they do for females. The cause of bladder stones is not well-understood, but factors that contribute to bladder stones include:
- Bad diet - A good diet of grass hay, fresh vegetables, and reasonable servings of low-calcium pellets are important. Too much calcium and oxalates may lead to stones.
- Insufficient water - Drinking plenty of water can dilute the urine and prevent stone formation.
Sometimes stones and sludge are found alongside infections, and sometimes not. Stones and sludge might lead to a UTI, but we've never heard anyone suggest that UTIs can lead to stone or sludge.