Hello, my name isXXXXX a veterinary surgeon and I'd be happy to answer your question.
Cephalexin concentrates well in the urine, however it is best for a class of bacteria known as "gram positive"
I don't have a culture
Gram positive bacteria are predominantly in the skin. The most common cause of urinary tract infections are fecal contaminants. These are mostly gram negative.
So long story short, cephalexin is not the best antibiotic for UTI's, but could still help.
Her vet is not open and she has blood in her urine. I hate to wait until Monday
You could certainly start her on it pending a culture. It may treat the UTI just fine, it just wouldn't be a first choice if you had access to others. How much does Maggie weigh and what size of capsules do you have?
She weighs about 14 pounds and they are 250 mgs. They were prescribed for her for a previous skin infection.
She should be fine with one capsule twice daily. Be sure to see a vet as soon as you can though. It'd be a good idea to make sure her diabetes is well managed. There's a chance glucose in her urine is causing this UTI.
Does that make sense? Do you have any other questions?
Is there anything else I can do for you?
No. Glad you were available.
It's a pleasure. I hope she feels better. I know UTI's can be very uncomfortable and hard to watch in your dog. I wish you all the best.