Abstract

Proventricular dilatation disease (PDD) is a neurologic syndrome of birds, caused by the infectious agent avian bornavirus (ABV).^4,5 Clinical disease is thought to be due to T-cell-mediated immune response to the presence of ABV within the nervous system.^2,3 Lymphoplasmacytic infiltrates can develop in the affected enteric ganglia; enteric nerve plexuses; brachial, vagus, optic, and sciatic nerves and/or the central nervous system. Treatment of PDD has thus far been unrewarding.³ Cyclosporine is an immunosuppressant drug that primarily decreases cell-mediated immune responses by inhibiting T-cell proliferation via calcineurin inhibition of growth cycles and decreased cytokine production.⁶ In avian species, cyclosporine is a proven potent immunosuppressant with T-cell-specific action and has been successfully used to induce immunosuppression in birds.^1,7 In this series of eight clinical cases of psittacine birds (two Ara chloropterus, one Ara ararauna, one Ara rubrogenys, two Cacatua alba, one Psittacus erithacus, and one Pionus) affected with ABV, use of cyclosporine was successful in treating clinical signs and preventing progression of PDD in multiple birds without severe side effects. Furthermore, a pilot study performed in ABV-infected cockatiels showed increased weight gain and lack of morbidity and mortality associated with ABV infection and cyclosporine treatment during the study period (151–153 days). While clinical trials and/or prospective studies would be necessary to further scrutinize the use of cyclosporine in psittacine birds with PDD, initial results indicate that cyclosporine is a promising option for treatment of PDD in avian patients.

Acknowledgments

The authors recognize the Schubot Exotic Bird Health Center for their contribution to this work.

Literature Cited

1.  Hill JE, Rowland GN, Latimer KS, Brown J. Effects of cyclosporine A on reovirus-infected broilers. Avian Dis. 1989;33(1):86–92.

2.  Hoppes S, Gray PL, Payne S, Shivaprasad HL, Tizard I. The isolation, pathogenesis, diagnosis, transmission, and control of avian bornavirus and proventricular dilatation disease. Vet Clin North Am Exot Anim Pract. 2010;13(3):495–508.

3.  Hoppes SM, Tizard I, Shivaprasad HL. Avian bornavirus and proventricular dilatation disease: diagnostics, pathology, prevalence, and control. Vet Clin North Am Exot Anim Pract. 2013;16:339–355.

4.  Kistler AL, Gancz A, Clubb S, et al. Recovery of divergent avian bornaviruses from cases of proventricular dilatation disease: identification of a candidate etiologic agent. Virol J. 2008;31:88.

5.  Ouyang N, Storts R, Tian Y, et al. Histopathology and the detection of avian bornavirus in the nervous system of birds diagnosed with proventricular dilatation disease. Avian Pathol. 2009;38:393–401.

6.  Plumb DC. Cyclosporine. In: Plumb DC, Davidson G, eds. Plumb’s Veterinary Drug Handbook. 7th ed. Ames, IA: Wiley-Blackwell; 2011:352–357.

7.  Russell PH, Dwivedi PN, Davison TF. The effects of cyclosporin A and cyclophosphamide on the populations of B and T cells and virus in the harderian gland of chickens vaccinated with the Hitchner B1 strain of Newcastle disease virus. Vet Immunol Immunopathol. 1997;60(1–2):171–185.