We all know that Mastiffs are not built like a typical dog. Because of their huge chest cavities and slower circulation due to their sheer size, many Mastiffs have a specific inability to metabolize drugs in the normal time frame that other dogs do. Below I have compiled a very specific list of anesthesias that I personally consider unsafe or safe (or we’ll say ‘safer’) to use on Mastiffs. Please remember that any time you put any dog under anesthesia there is a risk, but hopefully if your vet is willing to do a little research and listen to you as a client, that risk can be minimized. It is your job to be the advocate for your pet, if you vet is unwilling to listen to your concerns or wants to use an anesthesia you aren't comfortable with, in my book that's the only indicator I need to find a new vet fast!
I wanted to note that much of this information was in summary taken from Dr. Robin M. Smith, DVM’s article Anesthesia and the Mastiff; however some is from my own personal experience or experiences of other Mastiff owners I am in communication with. Here's a link to Dr. Smith's full article if you are interested: Anesthesia and the Mastiff
Anesthesia’s not to be used on Mastiffs
· Acepromazine (Ace) - lowers blood pressure and dilates blood vessels, making blood pressure even lower. It also metabolizes very slowly and accumulates in fatty tissues.
· Xylazine (Rompum) - difficult to dose in giant breeds and makes dog susceptible to heart abnormalities.
· Sodium Penthathol (or any of the Thiopentals) - stays in the system a very long time, if leaks from vein it can irritate or kill the tissue.
· Halothane (gas) - sensitizes the heart and can cause irregular heartbeats - if used, closely monitor dog.
· Atrophine - causes gut to slow down and predispositions dog to bloat.
Anesthesia’s that are safer alternatives for Mastiffs
· Valium - not much effect on heart, can be used in conjunction with Ketamine.
· Ketamine - not much effect on heart, can be used in conjunction with Valium.
· Telazol - similar to Valium and Ketamine, but don't exceed a dose of 1.5cc total. (Some Mastiffs have recently had issues with this drug, so it may be moved to my ‘unsafe’ list soon)
· Propofol – generally safe, used for quickly knocking dog out. Dog recovers as soon as gas is removed. Can sometimes lower blood pressure though, so dog needs to be constantly monitored.
· Oxymorphone - can cause respitory depression in some dogs, so dog needs to be constantly monitored (Naloxone is the drug used to reverse Oxymorphone and seems to works well).