15 year-old male Boa Constrictor!

Species: Snake
Breed: Boa constrictor
Age: 15y
Gender: MALE

Source/History: Peripheral blood. No history provided.

Click here for the IDEXX Pathology Report on this case.

Microscopic Description:
The erythrocyte density appears adequate. There is a moderate leukocytosis, lymphocytosis, increased azurophils, eosinophils and basophils. Occasional erythrocytes, heterophils, few thrombocytes, and many lymphocytes are noted containing 1-2 small round to oval to elongate homogenous basophilic to glassy intracytoplasmic inclusions. In lymphocytes, these often displace the nucleus to the periphery of the cell. Thrombocyte clumps are observed; thrombocyte numbers appear adequate. No overtly neoplastic cells are seen.


Cytologic Interpretation/Comments:
The intracytoplasmic inclusions noted in the lymphocytes, heterophils, thrombocytes,
and erythrocytes are consistent with inclusion body disease (IBD) of boid snakes. This is a common and contagious disease seen in Boidae and Pythonida snakes. The etiologic agent has been identified as an arenavirus (genus Reptarenavirus). Common clinical signs include neurologic deficits and regurgitation; some snakes remain asymptomatic for long periods of time. Lymphoproliferative disorders have also been reported in boas with IBD. Boa constrictors appear to have a higher viral load, more inclusions, but less clinical signs and inflammation compared to ball pythons. Inclusions can also be seen in tissue sections of the CNS, lymphoid organs, and epithelial cells as eosinophilic inclusions. Although the reptarenavirus produces inclusions associated with IBD, inclusions do not indicate disease, and the disease does not require inclusions.


  1. Banajee K et al. What is your diagnosis? Blood film from a boa constrictor. Vet Clin Pathol. 2012(41/1);158-9.
  2. Chang L, Jacobson ER. Inclusion body disease, a worldwide infectious disease of boid snakes: a review. J Exotic Pet Med. 2010(19/3);216-25.
  3. Stenglein MD et al. Differential disease susceptibilities in experimentally reptarenavirus-infected boa constrictors and ball pythons. J Virol. 2017(91/15);1-14.

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