Sensitivity to Anesthesia
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    Senior Member cshellenberger's Avatar
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    Sensitivity to Anesthesia


    This is written about Mastiffs, but applies to all the Giant breeds and Brachcephatic (short faced) breeds
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    Anesthesia and the Mastiff

    By Robin M. Smith, DVM

    I thought that I would talk about anesthesia concerns and the mastiff since that is the most frequently asked question I get from mastiff owners.

    First off, you MUST have a veterinarian that is willing to listen to you and who is not afraid to be questioned about their anesthesia methods and how they monitor the pet once they are under anesthesia. If they do not want to discuss this or if they have a comment like, "well, I have always done it so and so way and I am not going to change", find yourself another veterinarian. I think that the public needs to be aware of exactly what is happening to their dogs and the risks that are possible. ALL anesthesias are putting the dog at risk... BUT there are some that are much safer than others and I will discuss these.

    To start, I want to mention a few anesthesias that I would avoid if at all possible. In the past, most of these drugs were used exclusively, but with the advent of the new drugs and safer ones, they should not be used in the mastiff. Mastiffs are not just big chihauhas. The mastiff generally has a slower heart rate than smaller dogs and they also have inherently a lower blood pressure. They also, as you know, have a larger body mass. These things add to the risk of anesthetizing them.

    I never use acepromazine anymore as a pre-anesthetic or tranquilizer. Acepromazine lowers blood pressure and dilates blood vessels thereby making the blood pressure even lower. It also is metabolized (gotten rid of by the body) very slowly and tends to accumulate in fatty tissues. Therefore, larger dogs and fatter dogs usually have to be given a larger dose than normal in order to have effect, and because of this, it takes these dogs sometimes days to get back to normal. I have used it a lot in the past... In fact, it was the "gold standard" for pre- anesthetic sedation, but not anymore. Many people have used it in tablet form for tranquilization during stressful periods, i.e. thunderstorms. Again, I used to use it for this, but do not now, especially in giant breeds... It is too unpredictable. Just to let you know, I use Benadryl for thunderstorms at a dose of 1 mg./lb but not to exceed 100 mg. and find it works very well to make the dog tired and rest better.

    Xylazine (Rompun) is another drug I avoid. I haven't used it in about 5 years. It makes the heart more susceptible to the effects of epinephrine (adrenalin) that is in the body and therefore, making the dog more susceptible to heart abnormalities. It is a difficult drug to dose in giant breed dogs.

    Acepromazine and Xylazine are the two drugs that I try to avoid if possible. If your veterinarian is also a large animal (cow, not mastiff) veterinarian, he may very well use the two drugs as they are used in farm animals a lot.

    If for some reason, your veterinarian must use these two drugs, I think it is mandatory that the dog be monitored by an EKG machine during surgery and immediately post-operatively.

    Other drugs that I do not use much although they are still used are the thiopentals. These are like sodium pentathol. They work very rapidly to knock the dog down, but are very powerful and stay in the system a long time. Also if the drug gets out of the vein (like if the dogs jump) the thiopentals can irritate the surrounding area and completely slough the area (all the tissue dies).

    The drug(s) that I use the most in mastiffs are valium, ketamine, telazol, and propofol.

    A combination of valium and ketamine given intravenously will be enough to knock the dog down in order to insert the endotracheal tube. Both of these drugs are very safe and I use them a lot in the older dogs. Neither one effect the heart much.

    Telazol is very similar to valium and ketamine and also works well for anesthesia so that an endotracheal tube be place (I use .1 cc/lb and do not exceed 1.5 cc total).

    I do use propofol (deprivan) for short procedures, i.e. OFA radiographs. Propofol is a fairly new drug in the veterinary field but has been used for a long time in the human field. It is a milky solution that after opening a vial cannot be stored. It gets contaminated with bacteria very easily. Because it is expensive, the veterinarian may try to cut corners and use old leftover propofol that is sitting in the fridge. It is given to effect or in other words, it is given IV until the dog goes down and then the dog is intubated and put on gas. The GREAT thing about this drug is that as soon as the animal is taken off the gas, the dog is awake and can walk out without assistance. I have also used the drug in C-sections to sedate the dog long enough to insert the endotracheal tube. It is a very top of the line drug. I do find the dosages of propofol to be a lot lower than the manufacturers literature dosage. One added thing: Propofol can lower blood pressure so the pet needs to be monitored while on that.

    I also use oxymorphone for sedation and sometimes as the sole sedative for simple procedures like biopsy. It is an opiod and therefore it can cause respiratory depression, which means that the dog needs to be constantly monitored. There is a reversal agent called Naloxone that will reverse the effects of the drug and works quite well.

    I will always put the dog on gas for a fairly short procedure. Isoforane is a gas of choice since it has fewer side effects. Halothane is still being used by some veterinarians. I do not use it since it (just like xylazine) sensitizes the heart which can cause irregular beats. But, as long as the dog is properly monitored, there should be no problem.

    Prior to ANY anesthesia in any aged animal, I require a pre-anesthetic blood work up. I get a PCV (monitors whether anemic or dehydrated), a BUN (monitors liver and kidney function), Creatinine (monitors kidney function), ALT (monitors liver function), Alkaline phosphates (monitors liver and the biliary system), Total protein (monitors the immune system and hydration status), glucose and the electrolytes (sodium, potassium and chloride). I get these as I said even in young animals... It is just good medicine to know where the dog is prior to surgery and anesthesia so we will know how they will tolerate anesthesia. It is the base line. These test also guide me to my use of anesthesia. For example, if there is kidney damage I know to avoid drugs that have to go through the kidney to be eliminated from the body. The temperature is also monitored along with the heart by an EKG.

    Atrophine was a drug that was used all the time as a pre-medication to dry up the saliva in dogs and cats and to keep the heart rate up. It is not used much anymore, or shouldn't be used in large and giant breeds. I don't use it in any breed anymore. Atrophine causes the gut to slow down and this is not good especially in the mastiff. I believe slowing the gut down predisposes the mastiff to bloating.

    Anesthetic Protocols:

    Routine spay or neuter. I hate the word ROUTINE used here because no surgery is routine. I used valium at .3 mg/kg and ketamine at 10 mg/kg IV and then I put the tube down the trachea and start the dog on isoforane gas anesthetic. I have not had problems with these in the mastiff.
    OFA radiographs. I know many of you try to get OFA radiographs while the animal is awake. An unsedated animal is very hard to position correctly, but even more importantly OFA asks you to sedate the dogs. OFA believes that by not sedating the dogs, we're not getting good representative x-rays. I believe if the OFA radiographs are done with sedation, it would be very hard to miss a dysplastic animal. Depending on if the dog is going to go right home or stay in the hospital. I will use 2 anesthetics for each case. If the dog is staying, I use the valium/ketamine mixture and if the dog is not staying, then I use the propofol and then the dog is intubated. Just another added note. I always put an IV catheter in for a quick access to the blood stream in case something does happen and I need to give drugs quickly.
    Cesearean Sections. The main goal here is to obtain the least sedation possible in the puppies. For the Ceaserain section, I utilize Propofol at a dose of 3 mg./ lb. or until I can get an endotracheal tube down the dog. If I had to choose a second choice I would give the bitch torbutrol and valium as a preanesthetic as described next and then intubate after masking down. I use torbugesic at .45 mg/kg and give it to the muscle. Then I give valium (.45 mg/kg) intramuscularly. We prep the bitch on the floor by shaving her belly and then when done, we put her on the table and mask her down. We put a large mask over her muzzle and turn the gas all the way until she is alseep enough to put the endotracheal tube in. While masking the bitch down, she may struggle since the dog thinks it is not getting oxygen, even though it is. The trick here is to get in and the puppies out ASAP. Propofol can also be used and I have had good results with it. The bitch is wide awake as soon as the last staple is in. I am comfortable with either one.
    Those are probably the three most common surgeries I do on mastiffs. Don't let the anesthesia scare you. Where there is some risk has been lowered by doing all the blood work and the pre-op exams that I mentioned above.

    If you have any questions regarding anesthesia or just anything, please feel free to contact me.


    Robin M. Smith, DVM
    Westminster Veterinary Emergency/Trauma Center
    269 W. Main St., Westminster, MD 21557
    Work 410-848-3363
    (Fax) 410-848-4959
    E-mail: [email protected]
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    Carla
    "A fool gives full vent to his anger, but a wise man keeps himself under control" Proverbs 29:11
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    Senior Member borzoimom's Avatar
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    Re: Sensitivity to Anesthesia

    VERY informative post! I have Borzois, and sighthounds also have problems with anethesia due to low body fat and fast metabolism getting them in trouble fast under anethesia.
    Thank you for the information!
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    Senior Member lovezois's Avatar
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    Re: Sensitivity to Anesthesia

    I agree with Bzoimom very informative post I too have Borzois so the same applies here.
    I have two Borzoi and two MinlH Dachshunds and last but not least Keri my Birman Cat,
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    Re: Sensitivity to Anesthesia

    With all due respect, I believe Dr. Smith needs to take a CE class in anesthesia or scan the anesthesia/analgesia board on VIN. I notice that she is not a member of the college of veterinary anesthesiologists, surgeons, dentists, or practitioners so she does not have any advanced anesthesia training. I have to disagree with a few of her points:
    Propofol has absolutely no pain control so I would hope that it is given to a c-section with a reversable opiate or epidural both of which are safe in c-sections. Locals should also be used.
    Oxymorphone is horrible as a sedative and often needs to be combined with a sedative such as valium, domitor, or even ace which at the proper dosages is very safe and used by many veterinary anesthesiologists.
    Thiopental is sodium pentothal and, again, in combination with other drugs and in the right situation can the proper induction agent. At 2-2.5% solution which most use it rarely causes sloughing.
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    Re: Sensitivity to Anesthesia

    My 2 cents:

    Seems to me that the original post has some good information on anesthesia, by a general practitioner who has taken some time to work out an anesthetic protocol that's safe and effective in large breeds. All of his/her points are valid and make pretty good sense to me.

    All of vabird's points, in the reply, seem petty and questionable, and I wonder what his/her credentials are that qualify him/her to offer advice on this topic. Board certified veterinary anesthesiologist? General practitioner? Certified vet tech? Lay person? In the interest of full disclosure, I'm a canine / feline veterinarian in general practice. It apears to me that Dr. Robin Smith is perfectly qualified to offer opinions on anesthesia even if she isn't a Boarded specialist.

    Dr. Jeff Perret
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    Re: Sensitivity to Anesthesia

    Dr. Jeff:
    I didn't mean to sound petty towards Dr. Smith. I don't know when she wrote that article or for what purpose. There isn't any publication info or studies listed. I think you will agree with me that there is quite a bit of misinformation on the web regarding all aspects of veterinary medicine. I have seen 13 year-old articles brought forward as the way to go for anethesia protocols. I have seen many questionable ideas repeated and spread throughout the blogosphere without studies to back them up.

    As to my credentials: I have been an LVT for 25 years, only practicing anesthesia. 5 of those years was spent as an anesthesia technician at a top-level veterinary school small animal hospital teaching vet students clinical anesthesia. I have taken countless CE hours in anesthesia every year and have kept up with the current knowledge. I am published. I have anesthetized dogs, cats, pet birds, raptors, rabbits, ferrets, hamsters, apes, snakes, siberian tigers, lions, land tortoises, etc; used most of the drugs (only on the animals, not myself!) and equipment currently on the market; and performed techniques such as epidurals and acupuncture. I would hold my anesthesia knowledge and experience against any small animal practioner. Now if you can get a board-certified vet or vet tech specialist to counter anything I've said, I will gladly accept their opinions. Well, and yours too. I would be happy to engage in a professional discussion, point by point, on the merits and problems associated with the drugs named above. That's what forums are for.

    I think it is a very big problem when someone goes to their vet and says you have to use "such and such" or you can't use "such and such" because of what I've read on the web. I have always said that the safest protocol is the one your vet is comfortable with and that if you have a concern about any drug you should voice that concern with your vet. If you don't like their answer then maybe that isn't the vet you should be seeing.
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    Senior Member BoxMeIn21's Avatar
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    Re: Sensitivity to Anesthesia

    Quote Originally Posted by vabird View Post
    I think it is a very big problem when someone goes to their vet and says you have to use "such and such" or you can't use "such and such" because of what I've read on the web. I have always said that the safest protocol is the one your vet is comfortable with and that if you have a concern about any drug you should voice that concern with your vet. If you don't like their answer then maybe that isn't the vet you should be seeing.
    Why is it a big problem for owners to educate themselves on what their dogs are sensitive to depending on the breed? I am glad I knew about ACE, 3 out of the 4 vets I questioned in regards to neutering my boxer would have used ACE - ACE has a documented cardiac effect on boxers. Unfortunately my friend did not know, neither did her vet, they used ACE and now her boxer is dead.

    "Please allow me to adjust my pants, so that I may dance the good time dance.
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    Re: Sensitivity to Anesthesia

    It is not wrong to educate yourself about your breed and related problems. You need to know where that info came from, though, and how old the info is. You have to realize that the practice of anesthesia is very complicated and very hard to minimize into a brief summary of drugs and protocols. It is constantly changing and being refined as we find out more about pain and the drugs we use. Instead of asking vets if they used ace in boxers and then said "bye, bye". Don't you think it would have been better to say "I have a really big concern about ace in boxers. Let's talk about it?"

    Here's the deal with ace in boxers: there isn't any evidence proving that boxers are sensitive to ace. There is anecdotal evidence that some boxers have had trouble with it. There is some strong acecdotal info about ace being a problem in a specific line of British boxers. There was one line in a veterinary book that warned of using ace in boxers. That line has since been removed in later editions. UC Davis 10 years ago put out a memo about 3 cases they had trouble with on ace. Was it the fact that they were boxers or just a coincidence that these individuals had a difficult time with the sedation for one reason or another? Soooo even with this knowledge many anesthesiologists, even some who own boxers, are still comfortable using it. Some are not. I know that ace is not used in the same way it was 10 years ago. There are some situations where ace is the best drug. If anyone else has any more info or knows about studies done, I would love to hear about it.

    I am very sorry about your friend's dog but there can be many reasons why a dog may not survive anesthesia.
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    Senior Member BoxMeIn21's Avatar
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    Re: Sensitivity to Anesthesia

    Quote Originally Posted by vabird View Post
    Instead of asking vets if they used ace in boxers and then said "bye, bye". Don't you think it would have been better to say "I have a really big concern about ace in boxers. Let's talk about it?"
    I didn't just say bye, bye - I had conversations regarding my concerns about the ABC's anouncement regarding ACE - and it was met with mixed results - one said it was a question of dosage, the other a complete myth, the third hadn't heard about it either way. My vet, thankfully, has seen a couple of incidences involving ACE and won't use it at all, on any breed.
    Quote Originally Posted by vabird View Post
    I am very sorry about your friend's dog but there can be many reasons why a dog may not survive anesthesia.
    Oh she made it through anesthesia just fine - it's when they got her home and she was listless, then later collapsed - she went into respiratory arrest then cardiac...all the the things the "anecdotal" evidence points to.

    Quote Originally Posted by vabird View Post
    Here's the deal with ace in boxers: there isn't any evidence proving that boxers are sensitive to ace.
    I didn't think we would find any scientific evidence proving that. LOL - would YOU volunteer your boxer for testing out anasthetics likely to kill him? Not many others around who would either. Not sure that anyone undertaking such a study could do so ethically either. But the fact remains that there have been enough incidences with ACE to have printed warnings in the Handbook of Veterinary Drugs, where the Acepromazine section states "Prolonged effects of the drug may be seen in older animals. Giant breeds, as well as greyhounds, appear quite sensitive to the clinical effects of the drug, yet terrier breeds appear more resistant. Boxer dogs, on the other hand, are predisposed to hypotensive and bradycardic effects of the drug."
    And then the ABC's warning here - by a vet.
    http://www.americanboxerclub.org/ace_boxers.html

    I also belong to an all boxer forum - there have been a number of members who have either lost their dog or nearly lost their dog to ACE. On top of that pretty much the whole boxer community warns against the use of ACE. So wouldn't it be prudent of vets not to use it at all? Especially since there are several safe - and more effective - alternatives (of course I don't know what they are offhand - valium, I think, and maybe isoflourane).
    Just two more of my cents

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    Re: Sensitivity to Anesthesia

    I'm not arguing with you. You have researched this topic in depth. Most, however, don't and jump to conclusions about drugs they really don't know.

    I do want to correct you on a few points, however.

    Especially since there are several safe - and more effective - alternatives (of course I don't know what they are offhand - valium, I think, and maybe isoflourane
    Yes, there are alternatives to ace but all drugs have their pluses and minuses so there are times when ace really is the only drug to use. Valium is not a good alternative since it isn't very dependable when given IM which is how ace is normally given. Ace is normally part of a preop. Isoflurane is used as a maintenance drug, never as a preop, and is a pretty horrible induction drug when used by itself.

    My vet, thankfully, has seen a couple of incidences involving ACE and won't use it at all, on any breed
    .
    I think just about every vet there is has drug they don't like. Ketamine, propofol, morphine, Domitor. You can find someone who doesn't like one of these for one reason or another. Usually because they used the wrong dosage for a particular situation. Personally, I don't care for Domitor which probably is the most substituted drug for ace but that doesn't mean I don't use it. It too has its strengths and weaknesses and times when it is the best drug for the job.

    would YOU volunteer your boxer for testing out anasthetics likely to kill him? Not many others around who would either.
    A retrospective study can be done where they look at the anesthesia records of cases done in the past and see if there are any patterns. I sure wish someone would.

    But the fact remains that there have been enough incidences with ACE to have printed warnings in the Handbook of Veterinary Drugs, where the Acepromazine section states "Prolonged effects of the drug may be seen in older animals. Giant breeds, as well as greyhounds, appear quite sensitive to the clinical effects of the drug, yet terrier breeds appear more resistant. Boxer dogs, on the other hand, are predisposed to hypotensive and bradycardic effects of the drug."
    I am fairly certain that this line has been removed from more recent editions but I will have to check to make sure.

    With all that being said and all the points you brought up there are board certified veterinary anesthesiologists who still say that ace is fine in boxers but at a lower dose. There are also some who prefer not to use it in boxers.
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