PET/CT FOLLOWING INTENSITY-MODULATED RADIATION THERAPY FOR PRIMARY LUNG TUMOR IN A DOG

A primary lung tumor in a dog treated with intensity-modulated radiation therapy was imaged approximately 6 weeks and 1-year posttreatment with combined positron emission tomography (PET) and computed tomography, utilizing the radiotracers 18F-fluorodeoxyglucose and 18F-fluorothymidine. These two tracers allowed discrimination of tumor from inflammation, and demonstrated spread of tumor along airways over time after treatment. Fusion of functional imaging with anatomic imaging is a useful tool, particularly in the field of oncology, with the potential for PET markers that delineate tumor from normal or reactive tissue, and potential or actual response to therapy.     

RADIOBIOLOGICAL AND TREATMENT PLANNING STUDY OF A SIMULTANEOUSLY INTEGRATED BOOST FOR CANINE NASAL TUMORS USING HELICAL TOMOTHERAPY

Feasibility of delivering a simultaneously integrated boost to canine nasal tumors using helical tomotherapy to improve tumor control probability (TCP) via an increase in total biological equivalent uniform dose (EUD) was evaluated. Eight dogs with varying size nasal tumors (5.8-110.9 cc) were replanned to 42 Gy to the nasal cavity and integrated dose boosts to gross disease of 45.2, 48.3, and 51.3 Gy in 10 fractions. EUD values were calculated for tumors and mean normalized total doses (NTD(mean)) for organs at risk (OAR). Normal Tissue Complication Probability (NTCP) values were obtained for OARs, and estimated TCP values were computed using a logistic dose-response model and based on deliverable EUD boost doses. Significant increases in estimated TCP to 54%, 74%, and 86% can be achieved with 10%, 23%, and 37% mean relative EUD boosts to the gross disease, respectively. NTCP values for blindness of either eye and for brain necrosis were < 0.01% for all boosts. Values for cataract development were 31%, 42%, and 46% for studied boost schemas, respectively. Average NTD(mean) to eyes and brain for mean EUD boosts were 10.2, 11.3, and 12.1 Gy3, and 7.5, 7.2, and 7.9 Gy2, respectively. Using helical tomotherapy, simultaneously integrated dose boosts can be delivered to increase the estimated TCP at 1-year without significantly increasing the NTD(mean) to eyes and brain. Delivery of these treatments in a prospective trial may allow quantification of a dose-response relationship in canine nasal tumors.     

MAGNETIC RESONANCE IMAGING CHARACTERISTICS OF PERIPHERAL NERVE SHEATH TUMORS OF THE CANINE BRACHIAL PLEXUS IN 18 DOGS

Magnetic resonance imaging (MRI) examinations from 18 dogs with a histologically confirmed peripheral nerve sheath tumor (PNST) of the brachial plexus were assessed retrospectively. Almost half (8/18) had a diffuse thickening of the brachial plexus nerve(s), six of which extended into the vertebral canal. The other 10/18 dogs had a nodule or mass in the axilla (1.2-338 cm3). Seven of those 10 masses also had diffuse nerve sheath thickening, three of which extended into the vertebral canal. The majority of tumors were hyperintense to muscle on T2-weighted images and isointense on T1-weighted images. Eight of 18 PNSTs had only minimal to mild contrast enhancement and many (13/18) enhanced heterogeneously following gadolinium DTPA administration. Transverse plane images with a large enough field of view (FOV) to include both axillae and the vertebral canal were essential, allowing in-slice comparison to detect lesions by asymmetry of structures. Higher resolution, smaller FOV, multiplanar examination of the cervicothoracic spine was important for appreciating nerve root and foraminal involvement. Short tau inversion recovery, T2-weighted, pre and postcontrast T1-weighted pulse sequences were all useful. Contrast enhancement was critical to detecting subtle diffuse nerve sheath involvement or small isointense nodules, and for accurately identifying the full extent of disease. Some canine brachial plexus tumors can be challenging to detect, requiring a rigorous multiplanar multi-pulse sequence MRI examination.     

Intraocular and Cardiopulmonary Effects of Low-dose Mannitol in the Dog

Fatal complications have been reported during anesthesia in dogs that received a standard (1–2 g/kg IV) dose of mannitol during intraocular surgery. A lower dose (0.25 g/kg IV), which had been shown to reduce intracranial pressure in humans, was evaluated during halothane anesthesia in dogs. There were no significant changes in intraocular pressure (IOP) or cardiovascular variables. This lower dose (0.25 g/kg IV) did not reduce IOP and would not be of benefit in dogs undergoing intraocular surgery.     

Bacterial Isolates From Plaque and From Blood During and After Routine Dental Procedures in Dogs

Objective — This study evaluates the association between dental procedures and bacteremia in dogs, including a comparison of bacteria isolated from plaque and blood, severity of the bacteremia versus the severity of dental disease, and the longevity of bacteremia.
Study Design — Bacteria cultured from the blood over time were compared with those isolated from the plaque and crevicular fluid and in relation to severity of dental disease.
Animals or Sample Population — Twenty adult greyhounds.
Methods — Blood samples were collected for culture before induction of general anesthesia, immediately after intubation, 20 minutes after initiation of the dental procedure, and at 10-minute intervals until 10 minutes after the dental procedure was completed. Samples of plaque were taken for microbiological culture.
Results — Sixty to ninety percent of the bacterial genera isolated from the plaque were present in the blood. Dogs classified according to severity of dental disease showed no difference in the total number of different species or number of different Gram-negative, Gram-positive, or anaerobic bacteria isolated from plaque or blood (P <.05). Bacteremia was present in all of the dogs studied, within 40 minutes from the initiation of the dental procedure, regardless of the severity of oral disease.
Conclusions — Gram-negative, Gram-positive, and anaerobic bacteria are present in blood during dental procedures; the bacteremia can persist beyond the dental procedure, and is not associated with the severity of dental disease.
Clinical Relevance — The nature and extent of bacteremia occuring during routine dental procedures is important in understanding a potential risk to dogs.     

Medial Plating for the Repair of Middle and Distal Diaphyseal Fractures of the Humerus in Dogs

Six middle and distal humeral shaft fractures in dogs were repaired by the application of a bone plate along the medial shaft of the humerus. In all animals, clinical and radiographic evidence of normal bone healing was observed. The bone plate and ancillary implants were removed from five dogs by 10 months. In none of the six dogs were any untoward effects of placing the bone plate along the medial shaft of the humerus detected nor were there any difficulties encountered with the medial humeral soft tissues.     

Placement of Multiple Full Pins for External Fixation Technique and Results in Four Dogs

A technique using a third bar and guide clamp was developed to permit reduction and stabilization of distal limb fractures with full pins and two connecting bars, one on each side of the bone. The system uses only single Kirschner clamps. Four distal limb fractures were stabilized using this technique. Closed reduction was used in three dogs to avoid devitalization of fragments and avoid contamination of a closed fracture. The fracture site stability achieved with this configuration allowed early return to weight bearing and rapid bone healing.     

Is There a Trade and Defense Perimeter? The Regional Impacts of Trade and Defense Spending in the United States, 1978-1986

Using an expanded shift share technique to impute international trade-related industrial job change, the extent to which structural changes in trade and defense spending appear to explain state economic performance differentials is explored. The findings show there is limited support for the “trade perimeter” argument, but strong support for the hypothesized relationship between military procurement spending and state trade performance. To the extent that defense commitments, especially to private sector procurement and R & D, have operated as an informal industrial policy, particularly by guaranteeing strong domestic sales, they have enabled a significant number of states peripheral to the traditional industrial heartland to build a strong international trade posture. The conclusion offers observations on the economic development implications of these findings.     

Are We Moving Back to the City? Examining Residential Mobility in the Washington,DC Metropolitan Area

This research assesses the extent to which there is evidence of population re‐centralization or back to the city moves by tracking the historical trend of household and income mobility in the Washington, DC metropolitan area. County‐to‐county migration data and four migration efficiency measures are used to investigate net flows of households and income in the region. The results show a nascent tendency of back to the city movement; however, the redistribution of households and income in the metropolitan area is more complex. While the region's core may be starting to gain households and income, there are still significant flows into the region's most distant suburbs. The results of this research have implications for transportation, housing, and economic development policy making in Washington, DC and other regions. The study also offers a unique example of how to study household and income redistribution within U.S. metropolitan areas.