An approximately 5-month-old laboratory wether, originating from a local vendor with a closed flock and maintained on a preventative medicine plan, presented with a continuum of lesions from hemorrhagic papules, vesicles, and pustules, to multifocal necrotic scabs at the commissure of the lips, medial canthus of the left eye, and distal prepuce. A presumptive diagnosis of Orf virus (ORFV) was made and the sheep was euthanized. A full necropsy was performed, and histopathological evaluation of affected tissues revealed multifocal-to-coalescing necrotizing and proliferative cheilitis and dermatitis with eosinophilic intracytoplasmic inclusion bodies. Electron microscopy findings revealed degenerate keratinocytes containing numerous typical 200–300？nm wide cytoplasmic parapoxvirus virions, confirming the diagnosis of ORFV. We believe that this animal developed a clinical case of ORFV either due to an adverse reaction to an ORFV vaccine, or this animal had a case of preexisting ORFV which manifested after arrival at our facility. 1. Case History and Presentation On June 13, 2012, an approximately 5-month-old, 24？kg, Dorset wether (Ovis aries) was introduced to our facility from a local vendor. Upon arrival, this animal was determined to be healthy based on history, general health, and physical exam. The health certificate that accompanied the animal indicated it had been examined and was clinically free of ORFV, keratoconjunctivitis, contagious foot-rot, and scabies. The WRAIR/NMRC protocol requires all wethers to be sheared, docked, negative for Q fever and ORFV, and dewormed prior to shipment. This animal was acclimated in our vivarium. During the first four days of the acclimation period, the sheep displayed no abnormal behavioral or clinical signs. It demonstrated a healthy appetite and was fed ad libitum Rumilab diet 5508 (LabDiet supplier, Quality Lab Products, Elkridge, MD, USA), Timothy Hay (Kaytee Products, Inc., Chilton, WI, USA), and received water ad libitum. This Dorset sheep was pair-housed in a standard large animal aluminum run with polyvinyl chloride- (PVC-) coated steel mesh floor racks. The environment was maintained at 68 to 72 degrees F, with a relative humidity range of 30 to 70% and a 12？:？12-hour light？:？dark cycle. Environmental enrichment was provided in accordance with institute standard operating procedures. All animal handling and husbandry were performed by trained personnel, and the facility was maintained according to accepted animal care and use standards [1]. The sheep was procured for a protocol reviewed and approved by
References
[1]
Institute for Laboratory Animal Research, Guide for the Care and Use of Laboratory Animals, National Academies Press, Washington, DC, USA, 8th edition, 2011.
[2]
D. E. Anderson, D. M. Rings, and D. G. Pugh, “Diseases of the integumentary system,” in Sheep and Goat Medicine, D. G. Pugh, Ed., pp. 203–204, W.B. Saunders Company, Philadelphia, Pa, USA, 1st edition, 2002.
[3]
D. Deane, C. J. Mcinnes, A. Percival et al., “Orf virus encodes a novel secreted protein inhibitor of granulocyte-macrophage colony-stimulating factor and interleukin-2,” Journal of Virology, vol. 74, no. 3, pp. 1313–1320, 2000.
[4]
H. B. Gelberg, “Alimentary system and the peritoneum, omentum, mesentery, and peritoneal cavity,” in Pathologic Basis of Veterinary Disease, J. F. Zachary and M. D. McGavin, Eds., pp. 326–327, Elsevier, St. Louis, Mo, USA, 5th edition, 2012.
[5]
P. E. Ginn, J. E. K. L. Mansell, and P. M. Rakich, “Skin and appendages,” in Jubb, Kennedy, and Palmer’s Pathology of Domesic Animals, M. G. Maxie, Ed., vol. 1, pp. 664–666, Elsevier, Philadelphia, Pa, USA, 5th edition, 2007.
[6]
D. M. Haig, “Subversion and piracy: DNA viruses and immune evasion,” Research in Veterinary Science, vol. 70, no. 3, pp. 205–219, 2001.
[7]
D. M. Haig, “Orf virus infection and host immunity,” Current Opinion in Infectious Diseases, vol. 19, no. 2, pp. 127–131, 2006.
[8]
D. M. Haig, C. J. Mcinnes, J. Thomson, A. Wood, K. Bunyan, and A. Mercer, “The orf virus OV20.0L gene product is involved in interferon resistance and inhibits an interferon-inducible, double-stranded RNA-dependent kinase,” Immunology, vol. 93, no. 3, pp. 335–340, 1998.
[9]
D. M. Haig and A. A. Mercer, “Orf,” Veterinary Research, vol. 29, no. 3-4, pp. 311–326, 1998.
[10]
A. M. Hargis and P. E. Ginn, “The integument,” in Pathologic Basis of Veterinary Disease, J. F. Zachary and M. D. McGavin, Eds., p. 1023, Elsevier, St. Louis, Mo, USA, 5th edition, 2012.
[11]
F. A. Murphy, E. P. J. Gibbs, M. C. Horzinek, and M. J. Studdert, “Poxviridae,” in Veterinary Virology, pp. 289–291, Academic Press, San Diego, Calif, USA, 3rd edition, 1999.
[12]
C. B. Navarre, M. Q. Lowder, and D. G. Pugh, “Oral-esophageal diseases,” in Sheep and Goat Medicine, D. G. Pugh, Ed., pp. 66–67, W.B. Saunders Company, Philadelphia, Pa, USA, 1st edition, 2002.
[13]
L. J. Savory, S. A. Stacker, S. B. Fleming, B. E. Niven, and A. A. Mercer, “Viral vascular endothelial growth factor plays a critical role in orf virus infection,” Journal of Virology, vol. 74, no. 22, pp. 10699–10706, 2000.
[14]
I. R. Tizard, “Regulation of adaptive immunity,” in Veterinary Immunology, p. 217, Elsevier, St. Louis, Mo, USA, 9th edition, 2013.
[15]
International Committee on Taxonomy for Viruses, “Virus Taxonomy: 2012 release (current),” http://www.ictvonline.org/virusTaxonomy.asp?version=2012&bhcp=1.
[16]
J. F. Zachary, “Mechanisms of microbial infections,” in Pathologic Basis of Veterinary Disease, J. F. Zachary and M. D. McGavin, Eds., p. 210, Elsevier, St. Louis, Mo, USA, 5th edition, 2012.
[17]
N. F. Cheville and H. Lehmkuhl, “Cytopathology of viral diseases,” in Ultrastructural Pathology: The Comparative Cellular Basis of Disease, pp. 318–327, Wiley-Blackwell, Danvers, Mass, USA, 2nd edition, 2009.
[18]
Z. Lateef, S. Fleming, G. Halliday, L. Faulkner, A. Mercer, and M. Baird, “Orf virus-encoded interleukin-10 inhibits maturation, antigen presentation and migration of murine dendritic cells,” Journal of General Virology, vol. 84, no. 5, pp. 1101–1109, 2003.
[19]
MSD Animal Health United Kingdom, “Scabivax Forte Data Sheet,” 2012, http://www.msd-animal-health.co.uk/products_public/scabivax_forte/product_data_sheet.aspx.
[20]
J. J. Esposito and F. Fenner, “Poxviruses,” in Virology, pp. 2885–2916, Lippincott Williams and Wilkins, Philadelphia, Pa, USA, 4th edition, 2001.
[21]
D. A. Henderson, T. V. Inglesby, J. G. Bartlett et al., “Smallpox as a biological weapon: medical and public health management,” Journal of the American Medical Association, vol. 281, no. 22, pp. 2127–2137, 1999.
[22]
D. J. McClain, “Smallpox,” in Textbook of Military Medicine, pp. 539–559, Office of the Surgeon General, Borden Institute, Washington, DC, USA, 1997.
[23]
J. G. Breman and D. A. Henderson, “Diagnosis and management of smallpox,” New England Journal of Medicine, vol. 346, no. 17, pp. 1300–1308, 2002.
