Comparison of a new immobilization method using a reusable 3-point fixation cylinder system and bite-block type immobilization methods in veterinary radiotherapy.

In veterinary radiotherapy, highly reproducible immobilization is important for accurate irradiation. Consequently, we developed a new reusable head-immobilization method for dogs using cylinders. This study aimed to compare the accuracy of our novel immobilization method using cylinders with that of bite-block type immobilization methods. Three immobilization methods were compared: bite-block only, bite-block combined with torso immobilization, and immobilization using cylinders. Five beagles with canine teeth underwent CT five times for each of the three immobilization methods. One beagle without canine teeth underwent CT 15 times using each method. Three maxillary landmarks (maxillary incisor, frontal sinus, and occipital bone) and one mandibular landmark (mandibular incisor) were established, and the errors in each immobilization method were measured. For all head landmarks, the error in the immobilization method using cylinders was the most reproducible, with the smallest errors. No significant differences were observed in the time required for immobilization. Although there were limitations (such as the use of dogs from a single breed, a single episode of anesthesia, no disassembly of the immobilization system between scans, and the same person performing the positioning on the same day), we found our new reusable immobilization method using cylinders was the most accurate among the three compared methods. This was a proof-of-principle study to evaluate head immobilization using cylinders, and further investigations are needed to confirm its clinical utility.

Safety of alternate-day treatment with TS-1TM (tegafur/gimeracil/oteracil) in tumor-bearing dogs: a pilot study.

Tegafur is a prodrug of fluoropyrimidine 5-fluorouracil (5-FU), while TS-1TM is an oral fixed-dose combination of three active drugs, tegafur, gimeracil, and oteracil. This pilot study evaluated the safety of tegafur/gimeracil/oteracil in the treatment of cancers in dogs. Tegafur/gimeracil/oteracil was administered orally at a mean dose of 1.1 mg/kg twice daily on alternate days, Monday-Wednesday-Friday, every week to 11 dogs with tumors. Partial response and stable disease were observed in one dog each, whereas six exhibited progressive disease. Three dogs were not assessed. Adverse events, the most serious being grade 2, were noted in seven dogs. Adverse events were acceptable, and the drug was effective in some dogs. Therefore, tegafur/gimeracil/oteracil may be useful for treating malignant solid tumors in canines.