Refractory shock, hypercoagulability, and multiorgan thrombosis associated with hypertrophic osteodystrophy in a dog

To describe the clinical findings and case progression in a dog presenting with severe systemic inflammatory response, refractory shock, progressive metabolic acidosis, and respiratory failure that was ultimately diagnosed with hypertrophic osteodystrophy (HOD).

A 4-month-old male intact Mastiff presented with a 24-hour history of lethargy and generalized ostealgia. On examination, the dog was recumbent, febrile, and tachycardic with pain on palpation of the abdomen, right femur, and mandible. Appendicular joint radiographs showed changes consistent with osteochondrosis and ulnar-retained cartilaginous cores, with no overt evidence of HOD. Initial treatment included IV fluid therapy, multimodal analgesia, and broad-spectrum antimicrobials. Vasopressor therapy was initiated following hemodynamic decompensation. Synovial fluid cytological analysis and culture revealed nonseptic suppurative inflammation and no bacterial growth, respectively. Blood and urine cultures also yielded no growth. Viscoelastic testing was consistent with hypercoagulability. The dog initially had a metabolic acidosis with appropriate respiratory compensation that progressed to a mixed metabolic and respiratory acidosis despite aggressive therapies that included antimicrobials, vasopressors, positive inotropes, and corticosteroids. Humane euthanasia was elected approximately 32 hours after admission. Necropsy yielded a diagnosis of HOD.

This is the first report detailing the occurrence of refractory shock and hypercoagulability associated with HOD in a dog without evidence of another identified comorbidity. HOD should be considered in any young, large-breed dog with generalized ostealgia and signs of systemic illness, even in the absence of classic radiographic abnormalities. Further investigation of coagulation status in dogs with HOD and a secondary systemic inflammatory response is warranted.