Each pet's needs are individual and should be individually evaluated in regards to the need of pre-medications.The general description of how the procedure is performed is discussed on the Overview section and on the Understanding Euthanasia section.Injectable anesthetics now each have their specific reversal agents and the gas anesthetics we use are quickly reversed by ventilation as your pet breaths them out of it's system.These agents have dramatically reduced the risk to your pet.Many of the drugs that we use for anesthesia at one dose are sedatives at a lesser dose.
It is currently recommended that sedatives be used to calm an extremely fearful pet, those prone to severe separation anxiety and overactive pets.
In these situations, sedatives can work wonders to reduce the potential for the self-injury. Even nervous pets, once they are in a carrier in a quiet dark place, typically calm down and most even go to sleep.
The primary disadvantage of sedating pets for air travel is that there is no one to check on them nor offer medical care if problems arise. The most profound and potentially life threatening problem associated with sedation is the effect on blood pressure.
While there is always an exception to the rule, appropriate sedation is my preference for handling these patients, hands down! before radiographs, IV catheter, thoracocentesis, echocardiogram, etc.
Obviously I would prefer for the dyspneic patient to receive oxygen before, during, and after all interventions, but you've probably noted that some patients will struggle even if you are trying to blow some oxygen in their face; they may need sedation before you can even examine them.