Abstract

Hyperviscosity syndrome (HS) in people is caused by many conditions, ranging from inflammation to cyanosis to plasma cell dyscrasias.^2,4,6 It most commonly occurs due to elevations in gammaglobulins, either monoclonal in malignant disease, or polyclonal due to inflammatory conditions such as rheumatism.² Clinical signs of HS in people include altered mentation, visual impairment, and bleeding.^4,6 Hyperviscosity in domestic animals is usually a paraneoplastic syndrome, and has been reported with erythrocytosis and hypergammaglobulinemia secondary to hematopoietic neoplasia.⁵ Clinical signs in domestic animals can include erythematous mucus membranes, and neurologic and cardiovascular signs.¹ Hyperviscosity-like syndrome (HLS) in reptiles was first described in Kirtland’s snakes (Clonophis kirtlandii) with proliferative thyroid disease.³ In this Northwest ZooPath archival study, HLS was diagnosed in snakes and fewer lizards from a wide variety of taxonomic families. Females were more commonly diagnosed with HLS than males, and animals ranged from juvenile to 17 yr old. The most common clinical presentation was acute death without premonitory signs. Blood work was only available in a few cases, which had hyperglobulinemia. Common gross lesions included coelomic effusion, pulmonary edema, and hemorrhage. Histologically, animals consistently had deeply amphophilic fluid in the vasculature and interstitium (proteinaceous edema) in various organs, most commonly the lungs, heart, liver, and kidney. In the majority of cases, HLS was the most substantial finding and considered the most likely cause of death. A minority of cases had substantial concurrent disease, including gout, bacterial infection, neoplasia, and yolk coelomitis. Possible predisposing factors to HLS include hypothermia, sepsis, and endocrine abnormalities.

Acknowledgments

The authors thank institutions and individuals for contributing case material to this study, including Arizona Sonoran Desert Museum, Buffalo Zoo, Central Florida Zoo, Cleveland Metroparks Zoo, Columbus Zoo, Dallas Zoo, El Paso Zoo, Gladys Porter Zoo, Henry Doorly Zoo, Indianapolis Zoo, Jacksonville Zoo, Los Angeles Zoo, Louisville Zoo, Louisiana State University, Memphis Zoo, Micanopy Animal Hospital, Mobile Veterinary Services, Oklahoma City Zoo, Phoenix Zoo, Seneca Park Zoo, Stowers Institute, and Toledo Zoo. Additionally, the authors thank Christie Buie and Cathy Minogue of Northwest ZooPath for data retrieval and Leroy Brown of Histology Consultation Services for slide preparation.

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