Osteomyelitis of the pelvis caused by Rhodococcus equi in a two-year-old horse

Skeletal scintigraphy in the horse: Current indications and validity as a diagnostic test

Gamma scintigraphy is a well established imaging modality, which in equine practice is predominantly used in the investigation of lameness and suspected musculoskeletal problems. Whilst there is a growing literature on the indications for scintigraphy in the horse, there has been little emphasis so far on identifying the validity of scintigraphy as a diagnostic test. In particular, to what extent can the results of a scintigraphic examination be trusted? In this opinionated review the current indications for skeletal scintigraphy in the horse are considered and its validity as a diagnostic test reviewed. It is concluded that in the majority of published studies, inherent biases in study design make it difficult to assess accurately the validity of skeletal scintigraphy in the horse. Further well designed, prospective studies are required to assess the validity of skeletal scintigraphy as a diagnostic tool, particularly in horses with subtle alterations in radiopharmaceutical uptake.

Intracranial abscess caused byRhodococcus equiinfection in a foal

CASE DESCRIPTION

A 4-month-old Missouri Fox Trotter colt was examined for a 5-week history of head tilt after treatment for suspected pulmonary Rhodococcus equi infection.

CLINICAL FINDINGS

Computed tomography revealed osteolysis of the occipital, temporal, and caudal portion of the parietal bones of the left side of the cranium. A soft tissue mass compressing the occipital region of the cerebral cortex and cerebellum was associated with the osteolytic bone.

TREATMENT AND OUTCOME

A rostrotentorial-suboccipital craniectomy approach was performed to remove fragmented occipital bone, debulk the intracranial mass, and obtain tissue samples for histologic examination and bacterial culture. All neurologic deficits improved substantially within 3 days after surgery. Bacterial culture of the resected soft tissue and bone fragments yielded R equi.

CLINICAL RELEVANCE

Intracranial surgery in veterinary medicine has been limited to dogs and cats; however, in select cases, extrapolation of surgical techniques used in humans and small animals can assist with intracranial procedures in horses.

Non-skeletal scintigraphy of the horse: indications and validity

Gamma scintigraphy is an established imaging modality in the horse and is principally utilised to investigate skeletal disease using bone-seeking radiopharmaceuticals. However, depending on the radiopharmaceutical and imaging sequence, scintigraphy can be used to investigate disease in virtually any organ system. In this article the indications and validity of scintigraphy as a clinical diagnostic tool to investigate non-skeletal disease in the horse are reviewed. These indications include: investigation of dental disease, identification of inflammatory foci, vascular lesions, muscle and tendon pathology, assessment of physiological function of the lungs, gastrointestinal tract and other organs. Some of the techniques described for use in the horse have not been validated fully and as a result non-skeletal scintigraphy requires further investigation and validation using well-designed prospective studies. Such information can be used by clinicians to make informed decisions regarding the clinical and economic issues associated with a specific scintigraphic technique and may help when interpreting the results.