Sources of Variability in the Duration of Anesthesia in Snakes Dan Preston - PowerPoint PPT Presentation

Sources of variability in the duration of anesthesia in snakes dan preston l.jpg
Download
1 / 18

  • 311 Views
  • Uploaded on
  • Presentation posted in: Pets / Animals

Sources of Variability in the Duration of Anesthesia in Snakes Dan Preston. Mentors: Dr. Robert Mason, Department of Zoology Dr. Craig Mosley, College of Veterinary Medicine Oregon State University. Why Anesthetize Reptiles?. Anesthesia facilitates invasive procedures such as surgery

I am the owner, or an agent authorized to act on behalf of the owner, of the copyrighted work described.

Download Presentation

Sources of Variability in the Duration of Anesthesia in Snakes Dan Preston

An Image/Link below is provided (as is) to download presentation

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.


- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -

Presentation Transcript


Sources of variability in the duration of anesthesia in snakes dan preston l.jpg

Sources of Variability in the Duration of Anesthesia in Snakes Dan Preston

Mentors: Dr. Robert Mason, Department of Zoology

Dr. Craig Mosley, College of Veterinary Medicine

Oregon State University


Why anesthetize reptiles l.jpg

Why Anesthetize Reptiles?

  • Anesthesia facilitates invasive procedures such as surgery

  • Veterinary Medicine

    • Reptiles are pets

  • Research

    • Experiments often involve surgical procedures

Ihooq38/flickr.com


Challenges associated with reptile anesthesia l.jpg

Challenges Associated with Reptile Anesthesia

  • Risk of Mortality

  • Unique Physiology and Anatomy

  • Difficult Drug Administration

  • Variability in Anesthetic Effect

www.snakegetters.com


Anesthetic agents used on reptiles l.jpg

Anesthetic Agents used on Reptiles

  • Cold Narcosis, Inhalants and Injectables


Brevital sodium l.jpg

Brevital Sodium

  • Barbiturate anesthetic

  • Work in the brain at GABA receptors; suppress CNS

  • Widely used in many reptile taxa

  • Intramuscular or subcutaneous administration

  • Fast acting; short induction and recovery times

  • Variable effects across individuals


Questions l.jpg

Questions

  • What factors are responsible for variability between individuals?

  • How can anesthetic protocols be improved to create more consistent results?


Red sided garter snakes thamnophis sirtalis parietalis l.jpg

Red-sided Garter Snakes (Thamnophis sirtalis parietalis)

  • Well-studied

  • Large sample sizes

  • Easily maintained

    in captivity


Potential causes of variability in duration of anesthesia l.jpg

Potential Causes of Variability in Duration of Anesthesia

  • Body temperature

    -Reptiles are ectotherms; heart rate increases with body temperature

    -High temperatures increase rates of distribution and metabolism of anesthetics


Potential causes of variability in duration of anesthesia cont l.jpg

Potential Causes of Variability in Duration of Anesthesia cont.

2. Body condition

-Barbiturates distribute from blood to viscera, lean tissue and then accumulate in adipose tissue over time

C.R.Friesen


Potential causes of variability in duration of anesthesia cont10 l.jpg

Potential Causes of Variability in Duration of Anesthesia cont.

3. Time post-feeding

- Snakes have evolved to efficiently digest large meals at infrequent intervals

- Upregulate heart, gut and liver after feeding

- Brevital sodium distributes to the gut and is metabolized hepatically


Methods anesthetic protocol l.jpg

Methods: Anesthetic Protocol

  • Anesthetize snakes with 15 mg/kg subcutaneously

  • Record loss of righting ability, beginning and end of surgical anesthesia, return of righting ability

  • Measure body temperature every 30 min.


Methods experimental designs l.jpg

Methods: Experimental Designs

1. Body Temperature

-20 males, 3 temps. (21C, 26C, 31C)

-repeated measures

2. Body Condition

-45 females, 3 body condition groups, all at 21 C

-60-70 cm SVL, 60-120 g body weight

3. Time Post-feeding

-10 males, 10 females, all at 21 C

-anesthetized 1, 3, 10 days post-feeding

-dosage based on pre-feeding masses


Results body temperature l.jpg

Results: Body Temperature

One way ANOVA:

F2,17 = 12.71

P < 0.001

Post-hoc Tukey:

21 vs 31, P < 0.001

21 vs 26, P = 0.037

26 vs 31, P = 0.042


Results body condition l.jpg

Results: Body Condition

One way ANOVA:

F2,42 = 5.026

P = 0.011

Post-hoc Tukey:

Thin vs Fat, P = 0.008

Thin vs Med., P = 0.300

Med. vs Fat, P = 0.230


Results time post feeding l.jpg

Results: Time Post-feeding

One way repeated measures ANOVA:

F2,17 = 3.091

P =0.057


Conclusions l.jpg

Conclusions

1. Body temperature has strong effect

  • Increased heart rate likely reduces anesthetic duration

    2. Body condition has moderate effect

  • Shortened anesthetic duration with brevital sodium in fatter snakes is probably due to absorption by adipose tissue

    3. Time post-feeding did not have a detectable effect

  • Physiological changes during digestion may not have clinically significant effect on anesthesia

  • Further studies may clarify whether any effect exists


Acknowledgements l.jpg

Acknowledgements

Thanks to:

Dr. Robert Mason

Dr. Craig Mosley

Dr. Kevin Ahern

Rocky Parker

Chris Friesen

Howard Hughes Medical Institute


Pharmacokinetics of barbiturates l.jpg

Pharmacokinetics of Barbiturates

Thurmon, Tranquili and Benson. 1999. Essentials of Small Animal Anesthesia and Analgesia.


  • Login