That zoo vet sounds promising. The best rabbit vet in my area is also a zoo vet. Sometimes they have spots available for emergencies. I would call up first thing Monday(or tomorrow if they are open) and explain the severity of your buns condition(if you didn't already relay this info when making the appt.) and see if you can get in as an emergency appt., but do make sure they make the emergency appt. with the zoo vet and not another vet(unless the other vet will consult with the zoo vet as to how best to treat your bun). Just know it may cost more to be seen as an emergency appt.
The pen g procaine isn't going to work as well as the pen g procaine/benzathine. The benzathine is long acting, so keeps the blood serum levels up to work against the bacteria. If you read that last link I posted, the person that wrote the bicillin study clarifies the details of why it's important to use bicillin(pen g procaine/benzathine) and not just pen g procaine.
1 cc syringes are going to be better to use, especially if your bun isn't very big, as only a small amount is used, and the smaller syringe is needed to get an accurate dose measured. 20g is fine to draw up from the bottle, but you will need 22-23g to give the injection. And 1/2 in. might be too difficult to get the injection where it needs to be. I wouldn't use less than 3/4 in. I buy mine online, some pharmacies will sell them without a rx, or if you see that vet you could get them there if the vet wants you to go ahead with the pen g injections.
Good luck at the vets and I'm so glad you were finally able to find one that can help your bun.
The pen g procaine isn't going to work as well as the pen g procaine/benzathine. The benzathine is long acting, so keeps the blood serum levels up to work against the bacteria. If you read that last link I posted, the person that wrote the bicillin study clarifies the details of why it's important to use bicillin(pen g procaine/benzathine) and not just pen g procaine.
1 cc syringes are going to be better to use, especially if your bun isn't very big, as only a small amount is used, and the smaller syringe is needed to get an accurate dose measured. 20g is fine to draw up from the bottle, but you will need 22-23g to give the injection. And 1/2 in. might be too difficult to get the injection where it needs to be. I wouldn't use less than 3/4 in. I buy mine online, some pharmacies will sell them without a rx, or if you see that vet you could get them there if the vet wants you to go ahead with the pen g injections.
Good luck at the vets and I'm so glad you were finally able to find one that can help your bun.