I created a brief video on approaching the abdomen in a male dog. This is an essential approach to know if performing abdominal surgery on a male dog e.g. cryptorchid castration (go midline approach!)
My tip for approaching the caudal abdomen in a male, is to simply push the prepuce to the side then just stay on midline in the subcutaneous and rectus sheath (linear) layers. Prepare the prepuce in advance by flushing with dilute chlorhex so you can drape it in without concern. Do not veer off midline! The prepuce/ penis/ urethra are movable in this region, so there is no need to perform anything off midline. If you approach the abdomen off-centre and via the abdominal musculature you are more likely to encounter increased bleeding and this can reduce your exposure (especially if you do not have cautery) and increase surgical time. In the worst case scenario it can result in the surgeon making an error.
My other tip - before you start stand at the end of the surgical table and ensure the patient is straight. This will save you a lot of time, as once the drapes are on, it is not as clear where midline is, thus it is easy to go off-centre.