I am also wondering what medication is being injected. Wick had 25 days of shots, and concurrently had an oral antibiotic as well (details below):
For my Wick, his syphilis treatment in 2018 was penicillin injections (Penicillin G 300,000 iu/ml per ml) AND azithromycin (an oral antibiotic; Zithromax/Azithromycin 40mg/mL). From what I discussed with the vet, it is unusual to do to both the shots and oral antibiotic, but Wick, for a separate reason, actually had penicillin shots before (prior to us knowing about his syphilis), so we decided to do both treatments, in case his syphilis was penicillin-resistant. His shots started 10/15/2018 through 11/08/18, so that was 25 days of shots. Azithromycin started on 10/13/2018 thru 11/09/2018 (this started a few days earlier because we were given the wrong syringes for the penicillin, so we couldn’t start until we got new ones).
If your vet is using blood tests to determine your rabbit being in the clear, notably, before starting treatment, we did a treponema (syphilis) panel, which showed a weak positive [0.364; range is 0.299 – 0.4)]. Right after treatment, we took another blood sample for a new panel, it was a stronger positive (0.519). The panel tests for antibodies, not the infection itself (is my understanding). We did the panel 6 months later, and it was 0.508… so still positive. That being said, since treatment, Wick has had no symptoms, so we are running under the assumption that he is not positive.
The answers provided in this discussion are for general guideline purposes only. The information is not intended to diagnose or treat your pet. Seek the advice of your veterinarian or a qualified behaviorist.