Serial radiographic and ultrasonographic evaluation of discospondylitis in a cat: A case report of progressive vertebral lysis despite clinical improvement

A 10-year-old castrated male Korean Shorthair cat was presented with a 5-day history of lethargy and nonambulatory paraparesis. Neurological examination revealed delayed postural reactions in both pelvic limbs. Initial radiography of the lumbar spine revealed narrowing of the L7–S1 intervertebral disc space with ventral bony proliferation. Magnetic resonance imaging revealed collapse of the L7–S1 intervertebral disc space with heterogeneous T2-weighted hyperintensity and ventral contrast enhancement of the affected disc, as well as contrast enhancement of the adjacent paraspinal musculature. These findings suggested the presence of discospondylitis. Coccoid bacteria detected in both urine and splenic fine-needle aspirate indicated hematogenous spread. The cat was treated with broadspectrum antibiotics and corticosteroids. It showed neurological improvement within 1 month and complete resolution by 6 months. However, serial radiographs revealed progressive L7 vertebral endplate lysis and vertebral body shortening despite clinical improvement. In contrast, serial ultrasonography more clearly delineated the resolution of paravertebral soft tissue changes and the disappearance of perilesional fat edema, which correlated with clinical remission. Serial radiographic follow-up of feline discospondylitis is rarely reported. This case documents progressive vertebral lysis in a cat despite clinical recovery, demonstrating that radiographic severity may not correlate with clinical status in cats with discospondylitis and underscoring the complementary role of ultrasonography in monitoring paraspinal pathology.