Whip-Like Heterophil Projections in Reptiles: Art, Artifact, or Supportive of Inflammation?
American Association of Zoo Veterinarians Conference 2017
Nicole I. Stacy1,3, DVM, Dr med vet, DACVP; Terry M. Norton2, DVM, DACZM; Daniel Fredholm2, MS, DVM, DACZM; Carlos Rodriguez2, DVM, DACVP; Lidia Castro2; Craig Pelton1, DVM; John W. Harvey4, DVM, PhD, DACVP
1Department of Large Animal Clinical Sciences, College of Veterinary Medicine, University of Florida, Gainesville, FL, USA; 2Georgia Sea Turtle Center, Jekyll Island Authority, Jekyll Island, GA, USA; 3Disney’s Animals, Science, and Environment, Disney’s Animal Kingdom, Bay Lake, FL, USA; 4Department of Physiological Sciences, College of Veterinary Medicine, University of Florida, Gainesville, FL, USA
Heterophil morphologic changes in reptiles are well characterized regarding their clinical significance, including toxicity, left shifting, artifacts (e.g., from storage or drying), and presence of infectious agents.2 An unusual heterophil morphology was observed in 182 blood films representing 11 reptile species (150 chelonians, 31 snakes, 1 lizard) from 8 zoological institutions. As documented in one of these cases,1 this morphology was characterized by prominent, variably thick, curvilinear, whip-like cytoplasmic projections, which were the same color as heterophil granules. They were present in various proportions of total heterophils with a length of approximately one to three times the heterophil diameter. Most heterophils exhibited one long projection, but some cells had two or more projections trailing into opposite directions. The objective of this study was to evaluate blood films with heterophil projections for evidence of inflammation in the leukogram, and review the clinical history in order to determine the potential clinical significance of this morphologic change. Thirty-nine chelonians with repeat blood films exhibited heterophil projections over time during treatment. Artifacts from sample handling or blood film preparation techniques were excluded as a cause of the projections. The majority of cases (152/182) had concurrent heterophilia, heterophil left-shifting, and/or toxicity, and clinical history of conditions with underlying inflammatory disease; however, the remaining 30 blood film sets were from apparently healthy snakes. Although their cause and significance is unknown, considerations for heterophil projections include an artifact, activation of cells in vitro, or a cellular response to microbes or products of systemic inflammation in vivo.
The authors would like to thank all animal care professionals involved with medical care of the animals included in this study.
1. Stacy NI, Fredholm DV, Rodriguez C, Castro L, Harvey JW. Whip-like heterophil projections in consecutive blood films from an injured gopher tortoise (Gopherus polyphemus) with systemic inflammation. Vet Q. 2017;doi.org/10.1080/01652176.2017.1325538.
2. Strik NI, Alleman AR, Harr KE. Circulating inflammatory cells. In: Jacobson ER, ed. Infectious Diseases and Pathology of Reptiles: A Color Atlas and Text. Boca Raton, FL: CRC Press; 2007:167–218.