Gregory D. Roberts

Imaging techniques for avian lower respiratory diseases

Radiography is the most frequently used imaging technique to assess avian lower respiratory disease. The unique architecture of the avian respiratory system results in variations of radiographic appearances that are markedly different from the traditional pulmonary patterns frequently seen in mammals such as alveolar, bronchial, or interstitial. Alveolar lung disease, the hallmark of pneumonia in mammalian imaging, is not identified in avian lungs because the terminal airways consist of interconnecting bronchi and parabronchi without well-developed smaller compartments. Pathological changes of avian lungs are most commonly recognized radiographically as increased soft-tissue opacity with loss of the normal reticulated pattern. Avian lungs are relatively noncompliant and firmly adhered to the thoracic wall; thus, total lung volume is relatively constant throughout respiration, and conditions such as atelectasis do not occur. This review will address the common radiographic findings associated with avian lower respiratory disease. In addition, the potential applications of computerized axial tomography (CT) and magnetic resonance imaging (MRI) in avian respiratory disease will be discussed.

THORACIC VERTEBRAL CHORDOMA IN A DOMESTIC FERRET {MUSTELA PUTORIUS FURO)

Abstract A castrated adult male 1.0-kg domestic ferret (Mustela putorius furo) was referred for evaluation of a mass of >5 mo duration that was associated with the thoracic spine. The ferret had motor dysfunction and no conscious proprioception or pain perception in either hind limb. Segmental reflexes were present. Survey radiography, myelography, and magnetic resonance imaging showed a mass involving the ninth and 10 thoracic vertebrae and compressing the spinal cord. Decompressive surgery was performed, but clinical signs persisted. A diagnosis of chordoma was made using histopathology and immunohistochemistry. This is the first reported case of a chordoma involving the thoracic vertebrae in a domestic ferret.

Evaluation of the biliary and brain distribution of technetium Tc 99m sestamibi in healthy dogs with the ABCB1 wildtype genotype before and after treatment with spinosad

OBJECTIVE To determine whether the reported drug-drug interaction between the flea medication spinosad and ivermectin is attributable to inhibition of P-glycoprotein by spinosad. ANIMALS 6 healthy adult dogs with the ABCB1 wildtype genotype. PROCEDURES The study was conducted as a prospective, masked, randomized crossover design. Six dogs were allocated to 2 groups; each dog served as its own control animal. Dogs in one of the groups received spinosad at the manufacturers recommended dose; the other group received no treatment. Forty-eight hours later, scintigraphic imaging of the head and abdomen were performed with the radiolabeled P-glycoprotein substrate methoxy-isobutyl-isonitrile (sestamibi) in both groups of dogs. After a washout period of 60 days, the dogs in each group received the alternate treatment, and scintigraphic imaging again was performed 48 hours later. Gallbladder-to-liver and brain-to-neck musculature ratios of technetium Tc 99m sestamibi were calculated for each dog and compared between treatments. RESULTS No significant differences in gallbladder-to-liver or brain-to-neck musculature ratios were found between treatments. CONCLUSIONS AND CLINICAL RELEVANCE Results provided evidence that spinosad did not inhibit P-glycoprotein function 48 hours after spinosad was administered at the manufacturers recommended dose. Further investigations will be necessary to elucidate the mechanism of the reported toxic interaction between spinosad and ivermectin.