Susan L. Clubb, DVM, Dipl ABVP (Avian), Marcellus Buerkle, Dr. med. Vet, Lorenzo Crosta, Dr. med. Vet. (Avian), Paula G. Ciembor, DVM, PhD, Kenneth S. Latimer, DVM, PhD, Dipl ACVP, Michael M Garner, DVM, Dipl ACVP, and Branson Ritchie, DVM, PhD, Dipl ABVP (Avian)
Affiliation: From The Rainforest Clinic for Birds & Exotics, PO Box 508, Loxahatchee, FL 33470, USA (Clubb), Loro Parque, Puerto de la Cruz, Tenerife, Spain (Buerkle, Crosta), Infectious Diseases Laboratory, University of Georgia, Athens, GA 30602, USA(Ciembor), The Emerging Diseases Research Group. University of Georgia, Athens, GA 30602, USA (Ritchie, Latimer), and Northwest ZooPath, 18210 Waverly Drive, Snohomish, WA 98296, USA (Garner).
Feather damaging behavior (FDB) occurs frequently in lories and tends to be chronic. Lories have been identified as a group of parrots with an increased incidence of FDB of undetermined etiology.1 This study was designed to document the incidence and investigate possible etiologies of FBD in lories.
The lories used in this study are part of a large and stable collection of lories. They are housed in pairs in outdoor suspended breeding cages that are surrounded by plants. The diet varies among species including nectar, fruits, seeds, commercial extruded diet, and vitamin and mineral supplementation. Fresh food is offered twice daily. Despite excellent husbandry and species appropriate diets and social housing, the incidence of FBD in the collection was considered high (up to 22.5% depending on species).
Materials and Methods
Polymerase chain reaction (PCR)-based assays were used to attempt detection of circovirus nucleic acid in whole blood samples using circovirus nucleic acid primers (Institut fürVirologie, Universitat Leipzig, Leiter, IVULL, Germany) and specific psittacine circovirus 1 and psittacine circovirus 2 primer sets (University of Georgia Infectious Diseases Laboratory, IDL, Athen, GA, USA). The skin and feathers from affected areas were biopsied and evaluated for lesions consistent with psittacine circovirus and inflammatory skin disease by 2 pathologists. Biopsy samples were also evaluated using in situ hybridization with a psittacine circovirus specific DNA probe (in situ Hybridization Laboratory, University of Georgia, Athen, GA, USA). Plasma zinc levels were determined using a spectrophotometric 5-BR-PAPS assay (Laboratorios Taoro, Los Realejos, Tenerife, Spain).
The whole blood of 2 lories was positive for viral nucleic acid using a generic primer set (IVULL) on 3 separate occasions. Using variant specific primer sets, the whole blood from these 2 birds was positive for psittacine circovirus 2 and negative for psittacine circovirus 1 (IDL). Seven of 46 lories were diagnosed as blood-positive using generic primers (IVULL) that were negative using specific primers (IDL). Zinc levels were considered elevated (250–780g/dl, normal <200 g/dl) in 24 tested birds. Microscopic lesions suggestive of psittacine circovirus were not detected in any of the evaluated biopsy samples. Additionally, all birds were negative for psittacine circovirus following DNA in situ hybridization. Sixteen of 29 samples collected from visually abnormal skin had perivascular and/or perifollicular inflammation suggestive of a hypersensitivity dermatitis or cutaneous manifestation of a systemic illness with 16 birds showing lesions in samples from visually normal skin. A total of 23 of the 29 birds showed perivascular or peri-follicular inflammation.
The gross feather abnormalities in this group of lories are consistent with those described for FDB. Most were chronically affected and had feather abnormalities for years prior to a presumptive diagnosis of psittacine beak and feather disease based on gross feather lesions and detection of putative viral nucleic acid using generic PCR primers. Further evaluation indicated that the feather abnormalities were not consistent with those currently described for psittacine beak and feather disease and in situ hybridization using psittacine circovirus specific probes did not demonstrate the presence of viral nucleic acid. Zinc toxicity may have been a contributory factor in the inflammatory process; however, birds with normal plumage were not tested as controls.
The most important and consistent finding that could have resulted in the feather damaging behavior in these lories was inflammatory skin disease as characterized by perivascular and peri-follicular inflammation. These lesions are most consistent with a systemic inflammatory disease or allergy.
Acknowledgments: Study sponsored by the Loro Parque Fundacion, the MGARF Animal Health Fund, and the Infectious Diseases Laboratory.
1. Clubb SL, Elmo N, Burkle M, et al. Incidence and characterization of feather damaging behavior in a large parrot collection, Proc Annu Conf Assoc Avian Vet. 2004.
2. Garner MM. Avian noninfectious skin disorders. Proc Annu Conf Assoc Avian Vet. 2003;21–24.
3. Strunk A, Lester V, Ritchie BW, et al. Pathobiology and testing recommendations for psittacine circovirus 2 in lories. Proc Annu Conf Assoc Avian Vet. 2002;45–47.
4. Ritchie BW. Management of common avian infectious diseases. Proc West Annu Vet Conf. 2003.