JUVENILE CANINE DRUG-INDUCED ARTHROPATHY - CLINICO-PATHOLOGICAL STUDIES ON ARTICULAR LESIONS CAUSED BY OXOLINIC AND PIPEMIDIC ACIDS

Oxolinic acid and pipemidic acid [generally used as urinary antibacterial agents] were administered orally to young beagle dogs for 14 days. Dogs receiving oxolinic acid were hyperactive throughout the study and showed transient hindlimb stiffness on day 12. Dogs treated with pipemidic acid exhibited marked suppression of spontaneous activity and by day 4 were unable to stand and ambulated painfully. Both compounds induced gross alterations of the articular cartilage in major synovial joints, including solitary or multiple vesicles and erosions. Histopathologically, these changes were characterized by cartilage matrix rarefaction, cavitations, cartilage fibrillation and chondrocyte clustering predominantly in the intermediate zone. Hemorrhagic synovitis was a coincident finding in pipemidic-acid-treated dogs. Using lesion incidence and a scoring system which provided an overall estimation of both gross and microscopic findings, the arthropathic index was higher in dogs receiving pipemidic acid, demonstrating the greater arthropathogenic potential of this chemical. Lowered serum alkaline phosphatase values paralleled the arthropathies in each group. [Available reports indicate that alkyl pyridone carboxylic analogs used as urinary antibacterial agents damage the articular cartilage of immature animals.].