2016 Zoetis Clinical Challenges: GI Considerations in Anesthesia Symposium Proceedings

2016 Zoetis Clinical Challenges: GI Considerations in Anesthesia Symposium Proceedings

The following are the speaker responses to questions from the audience during the Symposium sponsored by Zoetis held Tuesday, March 8, 2016 at WVC in Las Vegas, NV.

The opinions expressed in these answers are those of the speakers and do not necessarily reflect the official label recommendations and point of view of the company or companies that manufacture and/or market any of the pharmaceutical agents, products, or services mentioned.

Session 1: Keys to Patient-Centered Orthopedic Care: It’s NOT All in the Operating Room!

Todd Tams, DVM, DACVIM (SAIM)
VCA, Los Angeles, CA

David C. Twedt, DVM, DACVIM (SAIM)
Colorado State University, Fort Collins, CO

Ross Palmer, DVM, MS, DACVS
Colorado State University, Fort Collins, CO

Ralph C. Harvey, DVM, MS, DACVAA
University of Tennessee, Knoxville, TN

No questions

Session 2: Chronic Vomiting in the Chronically Ill Dog & Cat

Todd Tams, DVM, DACVIM (SAIM)
VCA, Los Angeles, CA

David C. Twedt, DVM, DACVIM (SAIM)
Colorado State University, Fort Collins, CO

  1. Which diets with low copper do you recommend for dogs with chronic hepatitis?
    I recommend Royal Canin Veterinary Diet® Canine Hepatic™, Hill’s Prescription Diet® l/d®, or homemade diets. I believe all other commercial diets contain too much copper for dogs with chronic hepatitis.
  2. What is the primary cause for copper deposition in the liver? Is it diet related?
    In some dogs the cause is genetic, such as the Bedlington terrier, Dobermans, and Dalmatians. A recent study shows that Labradors likely have genetic aspects and then when fed a high-copper diets they accumulate copper. Following chelation, these dogs are maintained on low-copper diets. Other breeds and mixed breeds also accumulate copper and diet plays a significant role. We don’t know why some can handle it and others can’t. 
  3. When administering maropitant (Cerenia®) intravenously, should it be given slowly or does the rate matter? 
    Give slowly over a minute. We found that when Cerenia is administered as a rapid bolus dogs developed transient hypotension.
  4. Do you use Denamarin® for liver support? 
    Denamarin [S-adensosylmethionine (SAMe) and silybin] is a good product for liver support. I consider antioxidants such as vitamin E, milk thistle, or SAMe. Others can be used; however, I have limited experience with other liver antioxidants.
  5. Do all laboratories run copper levels on tissue or do you need a special lab? 
    Some diagnostic labs do their own copper analysis while others send them to other labs that do. Colorado State University does run liver copper analysis and some labs send their samples to us. 
  6. Do you regularly give mirtazapine for cats with chronic renal disease every 48 hours? 
    A pharmacokinetic study by Quimby found that dosing every 24 hours maintains blood levels in normal cats but recommends dosing every 48 hours in cats with chronic renal or liver disease. (Quimby JM, Lunn KF. Mirtazapine as an appetite stimulant and anti-emetic in cats with chronic kidney disease: a masked placebo-controlled crossover clinical trial. Vet J. 2013;197(3):651-655)
  7. When do you give Cerenia if using it preoperatively, and at what dose? 
    In many of my cases I give preoperative Cerenia at 1 mg/kg 30 minutes or so before induction. We find it prevents narcotic-associated vomiting and nausea and also improves postoperative recovery and results in a more rapid return to normal appetite.

Sessions 3 and 4:Preemptive Sedation – Making the Fear Disappear/Sedation and Anesthesia Protocols: Individualized Medicine

Ralph C. Harvey, DVM, MS, DACVAA
University of Tennessee, Knoxville, TN

  1. How do you deal with clients that do not want to pay the extra cost of sedation for procedures like x-rays?
    Dr. Harvey: Many clients and potential clients “shop around” for lower cost options. Most consumers desire “value” more than just lower costs. If and when our hospitals have the opportunity for conversation, clients will often embrace the added value that we can add by doing our best. They will agree to go with better options as we instruct them. Each practice in each demographic market must determine over time how they will choose to sustainably and profitably improve the standard of care in their hospital
  2. What is your favorite sedative for a dyspneic cat or dog?
    Dr. Harvey: A sedative with relatively little respiratory depression is acepromazine. Vasodilatation and hypotension are commonly caused by acepromazine, and we generally have used less acepromazine as other options have become available and the science and experience have guided the evolution of our practice. Butorphanol causes limited respiratory depression, and a combination of acepromazine and butorphanol provides even more sedation. Dexmedetomidine at lower doses can also be useful.
  3. Do you give cats intravenous (IV) dexmedetomidine? If so, at what dose?
    Dr. Harvey: I do use dexmedetomidine by either intramuscular (IM) or IV administration, generally at reduced doses. My most typical dose of dexmedetomidine in cats is 5‒10 micrograms per kilogram. The FDA-approved dose is 40 micrograms per kilogram.
  4. I am a shelter vet looking for a good protocol for older cats when screening is not an option.
    Dr. Harvey: I consulted my favorite shelter veterinarian, my wife. She uses the popular “TTD” cocktail (Telazol®/Torbugesic®/Dexdomitor®), followed by endotracheal intubation and isoflurane.
  5. I would love to get some guidance on trazodone use. Can it be given at home prior to a hospital visit for fearful or aggressive dogs? At what dose? When should it be given?
    Dr. Harvey: Yes, and we use it at 5 mg/kg. Clients will administer it either in the morning or both the evening before and the morning of the visit before bringing the patient to the hospital. Aggressive animals should never be assumed to become “safe” after any medication. Indeed, any medicated animal may respond atypically, and there is always the potential for undesirable behavior.
  6. What anesthetic fluid rate would you recommend for cats with chronic kidney disease?  Still 3 mL/kg?
    Dr. Harvey: We would like to have these animals well hydrated before anesthesia rather than relying just on intraoperative fluids. Then we would still use fluid rates lower than were popular in recent years. I refer you to the AAHA Fluid Therapy Guidelines
    https://www.aaha.org/professional/resources/fluid_therapy_download_center.aspx
  7. What is used for squirting in the mouth of cat for sedation?  Will this work with aggressive dogs?
    Dr. Harvey: One of our methods is to use a Luer-lock syringe with either an open-ended tomcat catheter or a needle as a device to squirt in the mouth of a hissing cat a mixture of ketamine, dexmedetomidine, and butorphanol. This synergistic combination is typically dosed at ketamine 2‒4 mg/kg, dexmedetomidine 10‒20 micrograms/kg, and butorphanol 0.2‒0.4 mg/kg for this oral route. It will work for some, but not all, aggressive dogs. Our favorite for aggressive dogs is a quick IM injection of Telazol at 4 mg/kg with butorphanol at 0.4 mg/kg. As always, please be careful out there!
  8. Can one use Simbadol™ (buprenorphine) and Onsior® (robenacoxib) together preoperatively followed by Onsior the next day?
    Dr. Harvey: Yes, and that will provide a balanced combination of opioid and NSAID, further complemented for a surgical procedure through the use of a local/regional anesthetic block.
  9. In the anesthetic protocols you discussed with dexmedetomidine with opioid and 2 mg/kg ketamine, do you use atropine as a premed?
    Dr. Harvey: No, we do not.
  10. Can you combine atropine with an opioid and dexmedetomidine at a 1 microgram/kg dose?
    Dr. Harvey: We would avoid use of the atropine, and instead try to take advantage of the bradycardia. Many good things happen during diastole!
  11. What is the “reduced dosage” of dexmedetomidine for agitated patients postoperatively?
    Dr. Harvey: We have been very pleased with the extra-label use of dexmedetomidine at 1 microgram/kg IV.
  12. What is the “Kitty Magic” cocktail?
    Dr. Harvey: It is the popular and useful combination of ketamine, dexmedetomidine, and butorphanol. There is a nice synergistic interaction, with each of these providing complementary receptor actions. Typical rather arbitrary doses are 0.1 to 0.2 cc of each of these given as an IM injection for a large cat. For a 5 kg cat, the doses would then be ketamine at 2‒4 mg/kg, dexmedetomidine at 10‒20 micrograms/kg, and butorphanol at 0.2‒0.4 mg/kg. This will typically provide deep sedation/light anesthesia and can serve as a prelude to general anesthesia with a GABA agonist, such as propofol or alfaxalone, and/or an inhalant anesthetic.
  13. Are the protocols of the Veterinary Anesthesia Support Group (VASG) website acceptable?
    Dr. Harvey: I can’t give a blanket approval for anyone’s collection of protocols or recommendations, not even my own without further discussion! Patients are never “uniform” and they all deserve individual consideration. But kudos to Dr. Bob Stein as founder and Executive Director of the VASG. It is a wonderful resource for us all. (http://www.vasg.org/)
  14. What about alfaxalone in an aggressive patient?
    Dr. Harvey: I am not aware of a significant body of literature specifically on this, but as a component of a combination or cocktail approach, it can be useful as a GABA agonist contributing to useful sedation. As an example, alfaxalone has been reported to be very useful in combination with a mixture of an opioid and dexmedetomidine. With the drug concentration of 10 mg/mL and a typical conservative dose of 1‒2 mg/kg in such combinations, the volume is a limiting factor for IM injections in larger patients.
  15. What about using low dose dexmedetomidine for stable, low-grade heart murmur patients for sedation (for example, wound management)?
    Dr. Harvey: The patient with an undefined heart murmur is a considerable unknown. Opioids are the mainstay of cardiac anesthesia and can be generally recommended. Alpha-2 agonists, including dexmedetomidine, are relatively contraindicated in dogs with valvular disease, myocardial infarction/tricuspid insufficiency, and ventricular dysfunction.
  16. What dose of dexmedetomidine do you use for sedation?
    Dr. Harvey: A useful resource for dosing in dogs is the Dexdomitor Dosing Chart: 
    https://www.zoetisus.com/products/pages/dexdomitor/PDFs/Dexdomitor-Dosing-Chart-Canine.PDF. Dosing is scaled to body surface area in dogs, typically with smaller dogs needing a higher dose per unit of body weight and larger dogs needing a lower dose per unit of body weight. The listed FDA-approved doses are higher than we typically use, particularly since we almost always combine the Dexdomitor with an opioid. Our most frequently used doses are about ½ of the listed 125 micrograms/meter2 dose that is derived from the chart. The dose in cats is not scaled to body surface area, but is listed as 40 micrograms/kg. Our typical dose in cats is 5‒10 micrograms/kg.
  17. What dose of dexmedetomidine do you use for postsurgical delirium?
    Dr. Harvey: The dose we use for postanesthetic delirium is 0.5 to 1.0 microgram/kg by IV injection. This is an off-label application that we find highly valuable and far better than our previous approach to delirium using acepromazine.
  18. What does of dexmedetomidine do you use as a premed?
    Dr. Harvey: See comments above.
  19. Can you give dexmedetomidine postop to a dog that was given acepromazine in its premed?
    Dr. Harvey: Yes.
  20. For healthy patients that are under anesthesia for 20 minutes or less, would you use a higher fluid rate?
    Dr. Harvey: Not necessarily. Patients should be well hydrated before anesthesia and surgery, but it is possible—and not uncommon—for current fluid rates to be a bit too high. Please refer to the AAHA Fluid Therapy Guidelines and Toolkit: <https://www.aaha.org/professional/resources/fluid_therapy_toolkit.aspx>
  21. A feral cat wakes up from ovariohystectomy dysphoric and thrashing following induction with Telazol and dexmedetomidine (IM), hydromorphone IM at prep, and an NSAID. What can be used to calm the cat?
    Dr. Harvey: There may be some important dosing data and other background unspecified in any hypothetical situation and therefore this question, but the first things to consider are keeping the situation safe for personnel and patient, quick determination of adequate pain management, and consideration of sedation with either acepromazine or dexmedetomidine. We work with many feral cats and they are often challenging patients.
 

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