Clinical and histologic features of a novel polyostotic proliferative bone disease in lovebirds (Agapornis spp)

To characterize the clinical and histologic features of a novel polyostotic osteoproliferative disease in lovebirds (Agapornis spp).

Records from select avian clinical and/or pathology diagnostic services in France, Australia, and Italy (2017 to 2024) and the US (1984 to 2024) were searched for clinical and pathological data from lovebirds with polyostotic osseous proliferations. Solitary lesions and suspect cases unconfirmed by imaging or postmortem examination were excluded. When available, fixed lesions were recut for independent histopathological re-examination by 5 veterinary pathologists to confirm consistency of diagnosis. Survival was assessed with a Kaplan-Meier curve.

22 cases from Australia, France, and Italy met the inclusion criteria, including 14 females, 5 males, and 3 of unknown sex. The median age at diagnosis was 3.5 years (range, 2 to 9 years). Apart from occasional palpation of osseous masses on physical examination, clinical signs were nonspecific and highly variable, corresponding with lesion location.

Imaging revealed several expansile lesions (with the sternum, skull, and vertebrae most often affected), while hematology and biochemistry were generally nonspecific. Lesions were confirmed to be the same disease process in all histologically examined cases and showed extensive woven bone proliferation, disrupting the normal medullary and cortical architecture of affected bones. Prognosis was guarded, with a mean survival time of 68 days. The condition was termed polyostotic osteopetrosis syndrome. The cause is unknown, although an inherited disorder is suspected.

Findings will assist clinicians in diagnosis and management of polyostotic osteopetrosis syndrome and provide foundations for further research.