Struvite in the tract as well as rememant ovarian tissue even after spaying may be the cause of the recurring UTI.
Females are particularly susceptible to UTIs.
Next Steps
urinalysis and urine culture would show a clear picture. Proper diagnostis to identify the root cause and thereby treat it with proper antibiotics and pain management for your pet.
Health Tips
If episodes of UTI occur more often and (predisposing) causes of UTI cannot be identified or corrected, long term low-dose therapy may be necessary. Consult with a vet for diagnosis and further treatment.