Accuracy of transcranial magnetic stimulation and a Bayesian latent class model for diagnosis of spinal cord dysfunction in horses

Background: Spinal cord dysfunction/compression and ataxia are common in horses. Presumptive diagnosis is most commonly based on neurological examination and cervical radiography, but the interest into the diagnostic value of transcranial magnetic stimulation (TMS) with recording of magnetic motor evoked potentials has increased. The problem for the evaluation of diagnostic tests for spinal cord dysfunction is the absence of a gold standard in the living animal. Objectives: To compare diagnostic accuracy of TMS, cervical radiography, and neurological examination. Animals: One hundred seventy-four horses admitted at the clinic for neurological examination. Methods: Retrospective comparison of neurological examination, cervical radiography, and different TMS criteria, using Bayesian latent class modeling to account for the absence of a gold standard. Results: The Bayesian estimate of the prevalence (95% CI) of spinal cord dysfunction was 58.1 (48.3%-68.3%). Sensitivity and specificity of neurological examination were 97.6 (91.4%-99.9%) and 74.7 (61.0%-96.3%), for radiography they were 43.0 (32.3%-54.6%) and 77.3 (67.1%-86.1%), respectively. Transcranial magnetic stimulation reached a sensitivity and specificity of 87.5 (68.2%-99.2%) and 97.4 (90.4%-99.9%). For TMS, the highest accuracy was obtained using the minimum latency time for the pelvic limbs (Youden's index = 0.85). In all evaluated models, cervical radiography performed poorest. Clinical Relevance: Transcranial magnetic stimulation-magnetic motor evoked potential (TMS-MMEP) was the best test to diagnose spinal cord disease, the neurological examination was the second best, but the accuracy of cervical radiography was low. Selecting animals based on neurological examination (highest sensitivity) and confirming disease by TMS-MMEP (highest specificity) would currently be the optimal diagnostic strategy

Chronic lameness caused by vascular compression of the iliac artery and vein by a malignant melanoma in the pelvis of a grey Spanish gelding

An 11‐year‐old grey Spanish gelding was presented with chronic lameness of the right hindlimb, with abduction of the limb during the swing phase. Based on a comprehensive lameness examination, the problem was localised to the pelvic region. Rectal and ultrasonographic examinations revealed a mass in the pelvic region in close association with the iliac artery and vein, and ultrasonographic indications of vascular compression. Considering the clinical presentation of a grey middle‐aged horse with multifocal melanoma‐like nodules at the level of the perineum, tail base, preputium and penis, a malignant melanoma with secondary vascular or neurological compression was suspected. Post‐mortem and histological examination confirmed the diagnosis of malignant melanoma with vascular compression of the iliac artery and vein and infiltrative growth in the iliac vein

Multifocal osteomyelitis and abdominal abscessation in a warmblood foal

To the authors' knowledge, this is the first report, in which a simultaneous occurrence of Salmonella-associated multifocal osteomyelitis and intra-abdominal abscessation in a foal presenting with weight loss, diarrhea and fever is described. No evidence of failure of passive immune transfer had been present at birth. Radiographic examination revealed multifocal type P osteomyelitis. Bacterial culture of synovial fluid revealed a Salmonella spp. Antibiotic treatment was adjusted based on the sensitivity results; however without clinical improvement. The foal developed abscess formations within the left femoral region, and finally a Salter Harris type I fracture of the left femur. Euthanasia was elected based on this finding. Post-mortem computed tomography revealed a large mass within the caudal abdomen that extended into the left pelvic and hind limb region, as well as multifocal osteomyelitis. Pathological examination identified the mass as a large abscess with multiple fistula tracts. Salmonella spp. was additionally cultured postmortem