Food Animal Drugs

Pregnant animal anesthesia

Pregnant animals have physiological changes that alter the anesthesia protocol and risks. Consider the following when developing your plan:

  • the fetus gets extra blood flow and oxygen; maternal cardiac output needs to meet the demand
    • pre/post oxygenate!
    • assist ventilation
  • maternal blood pressure is decreased by ~ 10% and circulating blood volume is increased by ~30%
  • animals placed in dorsal recumbency may have uterine compression of the aorta and vena cava
    • elevate the right hip to minimize the impact
  • maternal decreased functional lung capacity and maternal+fetal increased oxygen consumption
  • increased risk of maternal reflux and aspiration; hepatic function tests increased due to liver compression
    • secure airway; have suction available
  • maternal kidneys have increased blood flow and filtration rate
  • maternal decreased epidural space, CSF volume and increased sensitivity to local anesthetics
    • be extra careful in small ruminants
  • most anesthetic drugs get to the fetus
    • Epidural useful to decrease need

Drug impacts in the pregnant animal:

  • Acepromazine – safe in low doses, long acting, no reversal agent
  • Benzodiazepenes – tetraogenic in first trimester; “floppy baby syndrome” near term, nice in low doses, antagonist available
  • Alpha-2s – NOT recommended, lots of side effects
  • Opioids- fetal depression > maternal, nice in low doses, antagonist available
    • fentanyl is hard on baby, morphine is slower to cross placenta, limited buprenorphine goes to baby but no reversal available
  • Ketamine – higher neonatal mortality in puppies, increased uterine tone, no reversal; not recommended in small animals
  • Propofol, alfaxalone – safe
  • Inhalants -safe
  • GG- safe





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Large Animal Surgery - Supplemental Notes Copyright © by Erin Malone, DVM, PhD is licensed under a Creative Commons Attribution-NonCommercial 4.0 International License, except where otherwise noted.