A Necropsy Guide to Serpentes

Key Points

  • The postmortem exam is a key diagnostic tool in understanding the reasons for a snake’s morbidity and mortality. Necropsies can provide valuable information to provide a risk assessment for other animals in a population or collection and can help provide closure for a grieving owner.
  • Conduct necropsies in a systematic, thorough manner to ensure all pertinent tissues are evaluated and collected.
  • Make every effort to maintain sterility to ensure culture results on fresh tissue are accurate and do not reflect contamination.
  • For tiny patients, open the coelom, examine coelomic contents, take fresh samples, and submerge the entire animal in formalin, using a 10:1 ratio of formalin-to-tissue.
  • If the snake is venomous, carefully  disarticulate the head and transfer it into a non-compressible, formalin-filled container.
  • To begin the internal examination, place the snake in dorsal recumbency and begin a midline incision at the cloaca.
  • After evaluating the fat bodies and coelomic cavity, identify organs that are often difficult to find or that are easily “lost” during the necropsy procedure, such as the thymus, thyroid, and parathyroid glands.
  • The ophidian lung is a hollow sac that can be divided into a cranial respiratory portion and a caudal saccular portion. In many snakes, except for boas and pythons, the left lung is vestigial or significantly smaller than the right lung.
  • Normal ophidian kidneys are multilobular, with a dark brown, “stack of coins” appearance.
  • In males, the sexual segment of the nephron is a portion of the distal convoluted renal tubules.  The size of this segment is variable by season and reproductive activity, and may be grossly appreciated as pale tan, linear, streaks, and thus will require histopathology to rule out a pathologic change.
  • The gallbladder, spleen, and pancreas are closely associated in snakes in an arrangement that is often referred to as the “triad”. Some snakes possess a fused spleen and pancreas, also known as a splenopancreas.

The postmortem exam is a key diagnostic tool in understanding the reasons for a snake's morbidity and mortality. Necropsies can provide valuable information to provide a risk assessment for other animals in a population or collection and can help provide closure for a grieving owner. This manuscript reviews the snake necropsy in a systemic, thorough manner, describing normal anatomy and proper collection technique from head to tail . . .


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References


1. Farris SC, Squires MA, Ridgley F, et al. Necropsies of reptiles: recommendations and techniques for examining invasive species. UF IFAS Extension, University of Florida. December 2016. Available at edis.ifas.ufl.edu/pdffiles/UW/UW38200.pdf. Accessed July 29, 2019.


2. Funk RS, Bogan JE. Snake taxonomy, anatomy, and physiology. In: Divers SJ, Stahl SJ (eds). Mader’s Reptile and Amphibian Medicine and Surgery. St. Louis: Elsevier; 2019.


3. Garner, MM. The reptile necropsy: Collection and submission of pathologic samples. Proc North American Veterinary Conference, Jan. 8-12, 2005, Orlando, Florida. Available at ivis.org/proceedings/navc/2005/SAE/537.pdf?LA=1. Accessed July 29, 2019.


4. Gottdenker N, Yau W. Necropsy. In: Divers SJ, Stahl SJ (eds). Mader’s Reptile and Amphibian Medicine and Surgery. St. Louis: Elsevier; 2019.


5. Hanley CS, Hernandez Divers S. Practical gross pathology of reptiles. Semin Avian Exotic Pet Med 12(2):71-80, 2003.


6. McAloose D, Colegrove KM, Newton AL. Wildlife necropsy. In: Terio K, McAloose D, St. Leger J (eds). Pathology of Wildlife and Zoo Animals. San Diego; Academic Press; 2018: 1-9, 11-19.


7. Melidone R, Gibson CJ. Necropsy techniques in reptiles Part 2: Snakes. UK Vet Companion Animal. Vol 15, No 6, July 2010. Available at doi.org/10.1111/j.2044-3862.2010.tb00500.x. Accessed July 29, 2019.


8. Ossiboff RJ. Serpentes. In: Terio K, McAloose D, St. Leger J (eds). Pathology of Wildlife and Zoo Animals. San Diego; Academic Press; 2018: 897-916.


9. Schilliger L, Girling S. Cardiology. In: Divers SJ, Stahl SJ (eds). Mader’s Reptile and Amphibian Medicine and Surgery. St. Louis: Elsevier; 2019.


10. Sever DM. Ultrastructure of the reproductive system of the black swamp snake (Seminatrix pygaea). VI. Anterior testicular ducts and their nomenclature. J Morphol. 271(1):104-115, 2010. doi: 10.1002/jmor.10784


11. Sever DM, Freeborn LR. Observations on the anterior testicular ducts in snakes with emphasis on sea snakes and ultrastructure in the yellow-bellied sea snake, Pelamis platurus. J Morphol. 273(3):324-336, 2012. doi: 10.1002/jmor.10784.


12. Stahl SJ, DeNardo DF. Theriogenology. In: Divers SJ, Stahl SJ (eds). Mader’s Reptile and Amphibian Medicine and Surgery. St. Louis: Elsevier; 2019.


13. Terrell SP, Stacy BA. Reptile necropsy techniques. In: Jacobson ER (ed). Infectious Diseases and Pathology of Reptiles. Boca Raton: CRC Press Taylor & Francis Group; 2007: 219-256.

Further reading

Girling JE. The reptilian oviduct:  a review of structure and function and directions for future research. J Exp Zool 293(2):141-170, 2002.

Jensen B, Moorman AF, Wang T. Structure and function of the hearts of lizards and snakes. Biol Rev Camb Philos Soc 89(2):302-336, 2014.

Martinson S. Reptile pathology:  Necropsy techniques. University of Prince Edward Island web site. Available at http://people.upei.ca/smartinson/Reptile_necropsy_techniques_2018.pdf. Accessed March 12, 2020.

Martinson S. Reptile pathology:  Noninfectious diseases. University of Prince Edward Island web site. Available at http://people.upei.ca/smartinson/Reptile_Pathology_Course_-_Noninfectious_Disease_2018.pdf. Accessed March 12, 2020.

To cite this page:

Elbert J, Comolli J. A necropsy guide to serpentes. LafeberVet Web site. May 2, 2020. Available at  https://lafeber.com/vet/a-necropsy-guide-to-serpentes/