[bullmastiff]

Another thing that can help you with cutting the risk of infection or from staph is to use betadine with your injection.

Rub the area several times with alcohol and then betadine. Your skin will get yellow from the betadine but when your done, you use alcohol to clean the betadine off. Betadine is what the hospital uses when you have surgery to kill the germs.
Even with the best of sterile practices you can still get an infection, but do your best to have the best clean practice before injections and use betadine and alcohol to cut the risk of bacteria.