scott@vtx-cpd.com
Forum Replies Created
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Replying to Jane Sedgewick 09/05/2025 - 09:59
Hi Jane,
There does seem to be a growing default toward using long courses of broad-spectrum antibiotics for any dog with struvite uroliths, especially when stones are still present or dissolution is being attempted. The rationale is usually that infection must be the root cause, and that as long as the stones are there, they must be harbouring bacteria and therefore need treatment. But I share your concern. This approach often lacks evidence and risks unnecessary antimicrobial use.
The ACVIM consensus guidelines (2023) and earlier guidance from the Minnesota Urolith Center are both quite clear that infection-induced struvites should be confirmed by urine culture, and that medical dissolution is highly effective when paired with short, culture-guided antibiotic therapy. Most infection-induced struvite uroliths dissolve within two to five weeks, and sterile struvites may dissolve even more quickly. The consensus recommends treating sporadic urinary tract infections with a three- to seven-day course of antibiotics, guided by culture and sensitivity. In dogs undergoing medical dissolution of infection-induced struvites, antibiotics should be continued until the stones have fully dissolved and the infection is cleared, ideally confirmed by follow-up urine culture. However, this does not mean multiple weeks of antibiotics are needed in all cases, with effective diet and proper monitoring, the total duration may still be shorter than what is commonly prescribed empirically.
One important nuance from the ACVIM statement is that routine urinalysis and pH measurement are not sufficient substitutes for aerobic bacterial urine culture, particularly when trying to differentiate sterile from infection-driven stones. That said, in environments where repeated cultures are difficult to justify, such as charity settings, monitoring urine pH and sediment can still offer useful indirect information. If the dog is on an appropriate urinary diet such as Hill’s c/d or Royal Canin Urinary SO and the pH remains low (under 6.5), the urine is less likely to support struvite precipitation or urease-producing bacterial growth. That alone isn’t diagnostic, but it does support the idea that the current management strategy is controlling the key risk factors.
To summarise, unless there is confirmed bacteriuria with a urease-producing organism like Staph pseudintermedius or Proteus, I would not recommend prolonged antibiotic use. If culture is not feasible, monitoring pH and sediment, together with radiographic follow-up to track dissolution, can guide decision-making. A persistent acidic urine and reduction in stone size over time are both strong indicators that you’re on the right track.
Hope that helps!
Scott 🙂
