Hello again Maureen, Posted your answer some ten minutes ago, here it is again ...
I am fine with the info you have given so far ... I have worked out an answer for you, please read it through and see what you think.
1. Amoxycillin would be a good antibiotic to treat UTIs in the dog and is frequently used by vets for this purpose.
2. The normal dose rate for amoxycillin which a vet might use in the dog ranges from between 5 to 12 mg per pound of your dog's bodyweight twice a day for a seven day period. For a UTI I personally would use a dose in the higher range, say 10 mg per pound.
For dogs weighing 58 pounds then this would equate as up to 580 mg twice a day.
3. Of course if Daisy does not quickly respond to antibiotics or deteriorates in any way then you should have a vet check her over without delay in any case.
4. Where I give clients information on drugs and dose rates I always try and provide a link so that they can check the accuracy of what I have said and check any contraindications etc.LINK.
I hope I have covered your question fully enough but if you would like further clarification or to talk things over a bit more then I will be on-line for the next hour or so and I will be more than pleased to continue working with you.