My vet told me the biggest concern with the oral meds is the risk of seizures. That’s the bad news, the good news is they’re generally avoidable. The seizures are caused by an overdose. Too much medication for the amount of dog. My dog rides the along the line between dosages at +/-50 lbs. he wants me to keep her under that weight so he can give her the lesser dosage and keep the seizure risk at a minimum.
Obviously I use the oral meds from Pet Pharmacy and haven’t had any issues. I trust my vet’s knowledge and abide by his recommendations.