External Radiation Dose to Owners of Canines Treated with ( 117m Sn) Radiosynoviorthesis for Osteoarthritis.

ABSTRACT: A novel device in the veterinary market uses a colloid containing radioactive 117m Sn to treat osteoarthritis in the synovial joints of canines. The technique of injecting a radioisotope to restore synovia is referred to as radiosynoviorthesis. The outpatient canine procedure uses a maximum administration of 222 MBq of 117m Sn injected into one or more joints. Due to the 13.91 d half-life and 158.6 keV gamma output of 117m Sn, abiding by the annual public dose limit of 1 mSv is of primary regulatory concern. The therapy protocol starts with a pre-screening questionnaire to establish owner and animal behavior patterns. The questionnaire is used to determine the duration of written time and distance limitations post therapy. In this study, external radiation doses to owners were measured by providing optically stimulated luminescent dosimeters (OSLD) for up to 30 d post-treatment of the pet. Twelve owners were measured over various time frames at two licensed locations independent of each other. In one location, the average (OSLD) measured 0.029 mSv over a 14-d wear period. In the second location, the average (OSLD) measured 0.057 mSv over a 30-d wear period; both values were well below the recommended annual public dose. The overall average extrapolated external radiation dose was estimated at 0.092 mSv, while the maximum dose estimate was 0.25 mSv. The (OSLD) results and extrapolated owner doses provide reasonable assurance that the public dose limits will be met.

Use of magnetic resonance imaging-guided biopsy of a vertebral body mass to diagnose osteosarcoma in a Rottweiler.

CASE DESCRIPTION A 9-year-old spayed female Rottweiler with hind limb ataxia was examined because of anorexia and an acute onset of hind limb paresis. CLINICAL FINDINGS Neurologic evaluation revealed hind limb ataxia and symmetric paraparesis with bilaterally abnormal hind limb postural reactions including hopping, hemiwalking, hemistanding, and delayed proprioception, which were suggestive of a lesion somewhere in the T3-L3 segment of the spinal cord. Thoracolumbar radiography revealed an abnormal radiopacity suggestive of a mass at T11. Two 3.5-cm-long osseous core biopsy specimens of the mass were obtained by MRI guidance. Histologic appearance of the specimens was consistent with osteosarcoma. TREATMENT AND OUTCOME The owners of the dog declined further treatment owing to a poor prognosis. The dog was euthanized within 12 months after diagnosis because of a declining quality of life. CLINICAL RELEVANCE The acquisition of biopsy specimens by MRI guidance is an emerging technique in veterinary medicine. As evidenced by the dog of this report, MRI-guided biopsy can be used to safely obtain diagnostic biopsy specimens from tissues at anatomic locations that are difficult to access. This technique can potentially be used to facilitate early diagnosis and treatment of disease, which could improve patient outcome. The MRI guidance technique described may also be useful for local administration of chemotherapeutics or radiofrequency ablation or cryoablation of various neoplasms of the vertebral column.

Influence of ketamine on the cardiopulmonary effects of intramuscular administration of dexmedetomidine-buprenorphine with subsequent reversal with atipamezole in dogs.

OBJECTIVE: To compare the cardiorespiratory effects of IM administration of dexmedetomidine-buprenorphine (DB) and dexmedetomidine-buprenorphine-ketamine (DBK) in dogs with subsequent reversal with atipamezole. DESIGN: Prospective, randomized crossover study. ANIMALS: 5 healthy dogs. PROCEDURES: Dogs were instrumented for cardiac output (CO) measurement and received DB (15 µg of dexmedetomidine/kg [6.8 µg/lb] and 40 µg of buprenorphine/kg [18.2 µg/lb]) or DBK (DB plus 3 mg of ketamine/kg [1.36 mg/lb]) in randomized order while breathing room air. Atipamezole (150 µg/kg [68.2 µg/lb], IM) was administered 1 hour later. Hemodynamic data were collected in the conscious dogs and then at 5, 10, 15, 20, 30, 45, and 60 minutes after drug administration. Lactate concentration was measured in mixed venous blood samples. Oxygen delivery (Do(2)) and oxygen consumption ([Formula: see text]o(2)) were calculated. RESULTS: Heart rate (HR), CO, and Do(2) decreased after DB and DBK administration. The [Formula: see text]o(2) did not change in the DB group but decreased in the DBK group. The HR was higher in the DBK group than in the DB group throughout the study, but the CO, Do(2), and [Formula: see text]o(2) values were similar for the 2 groups. Blood lactate concentrations remained low (< 1 mmol/L) throughout the study. Arterial hypoxemia and hypercapnea occurred in both groups. Mean arterial blood pressure and pulmonary artery wedge pressure were markedly increased in both groups, but to a greater extent in the DBK group. After atipamezole administration, HR, CO, and Do(2) returned to the baseline values. CONCLUSIONS AND CLINICAL RELEVANCE: Adding ketamine to the DB combination allowed dogs to maintain a higher HR and delayed the onset of sinus arrhythmias but failed to provide a significantly higher CO because of a reduction in stroke volume.

Evaluation of anesthetic, analgesic, and cardiorespiratory effects in dogs after intramuscular administration of dexmedetomidine-butorphanol-tiletamine-zolazepam or dexmedetomidine-tramadol-ketamine drug combinations.

OBJECTIVE: To compare anesthetic, analgesic, and cardiorespiratory effects in dogs after IM administration of dexmedetomidine (7.5 µg/kg)-butorphanol (0.15 mg/kg)-tiletamine-zolazepam (3.0 mg/kg; DBTZ) or dexmedetomidine (15.0 µg/kg)-tramadol (3.0 mg/kg)-ketamine (3.0 mg/kg; DTrK) combinations. ANIMALS: 6 healthy adult mixed-breed dogs. PROCEDURES: Each dog received DBTZ and DTrK in a randomized, crossover-design study with a 5-day interval between treatments. Cardiorespiratory variables and duration and quality of sedation-anesthesia (assessed via auditory stimulation and sedation-anesthesia scoring) and analgesia (assessed via algometry and electrical nerve stimulation) were evaluated at predetermined intervals. RESULTS: DBTZ or DTrK induced general anesthesia sufficient for endotracheal intubation ≤ 7 minutes after injection. Anesthetic quality and time from drug administration to standing recovery (131.5 vs 109.5 minutes after injection of DBTZ and DTrK, respectively) were similar between treatments. Duration of analgesia was significantly longer with DBTZ treatment, compared with DTrK treatment. Analgesic effects were significantly greater with DBTZ treatment than with DTrK treatment at several time points. Transient hypertension (mean arterial blood pressure > 135 mm Hg), bradycardia (heart rate < 60 beats/min), and hypoxemia (oxygen saturation < 90% via pulse oximetry) were detected during both treatments. Tidal volume decreased significantly from baseline with both treatments and was significantly lower after DBTZ administration, compared with DTrK, at several time points. CONCLUSIONS AND CLINICAL RELEVANCE: DBTZ or DTrK rapidly induced short-term anesthesia and analgesia in healthy dogs. Further research is needed to assess efficacy of these drug combinations for surgical anesthesia. Supplemental 100% oxygen should be provided when DBTZ or DTrK are used.

Hemodynamic effects in dogs after intramuscular administration of a combination of dexmedetomidine-butorphanol-tiletamine-zolazepam or dexmedetomidine-butorphanol-ketamine.

OBJECTIVE: To evaluate hemodynamic effects in dogs after IM administration of dexmedetomidine (7.5 µg/kg, butorphanol (0.15 mg/kg), and tiletamine-zolazepam (3 mg/kg [DBTZ]) or dexmedetomidine (15 µg/kg), butorphanol (0.3 mg/kg), and ketamine (3 mg/kg [DBK]). ANIMALS: 5 healthy adult mixed-breed dogs. PROCEDURES: Each dog received DBTZ and DBK in a randomized crossover study with a 48-hour interval between treatments. Anesthesia was induced and maintained with sevoflurane in 100% oxygen while instrumentation with Swan-Ganz and arterial catheters was performed. Following instrumentation, hemodynamic measurements were recorded at 3.54% (1.5 times the minimum alveolar concentration) sevoflurane; then sevoflurane administration was discontinued, and dogs were allowed to recover. Six hours after cessation of sevoflurane administration, baseline hemodynamic measurements were recorded, each dog was given an IM injection of DBTZ or DBK, and hemodynamic measurements were obtained at predetermined intervals for 70 minutes. RESULTS: DBTZ and DBK induced hypoventilation (Paco2, approx 60 to 70 mm Hg), respiratory acidosis (pH, approx 7.2), hypertension (mean arterial blood pressure, approx 115 to 174 mm Hg), increases in systemic vascular resistance, and reflex bradycardia. Cardiac output, oxygen delivery, and oxygen consumption following DBTZ or DBK administration were similar to those following sevoflurane administration to achieve a surgical plane of anesthesia. Blood l-lactate concentrations remained within the reference range at all times for all protocols. CONCLUSIONS AND CLINICAL RELEVANCE: In healthy dogs, both DBTZ and DBK maintained oxygen delivery and oxygen consumption to tissues and blood lactate concentrations within the reference range. However, ventilation should be carefully monitored and assisted when necessary to prevent hypoventilation.

Evaluation of dexmedetomidine and ketamine in combination with various opioids as injectable anesthetic combinations for castration in cats.

OBJECTIVE: To compare the efficacy and cardiorespiratory effects of dexmedetomidine-ketamine in combination with butorphanol, hydromorphone, or buprenorphine with or without reversal by atipamezole in cats undergoing castration. DESIGN: Prospective, randomized, split-plot, blinded study. ANIMALS: 30 healthy male cats. PROCEDURES: Cats were assigned to receive dexmedetomidine (25 ?g/kg [11.4 ?g/lb]) and ketamine (3 mg/kg [1.4 mg/lb]) with butorphanol (0.2 mg/kg [0.09 mg/lb]; DKBut; n = 10), hydromorphone (0.05 mg/kg [0.023 mg/lb]; DKH; 10), or buprenorphine (30 ?g/kg [13.6 ?g/lb]; DKBup; 10). Drugs were administered as a single IM injection. Supplemental isoflurane was administered to cats if the level of anesthesia was inadequate for surgery. At the conclusion of surgery, half the cats (5 cats in each treatment group) received atipamezole (250 ?g/kg [113.6 ?g/lb], IM) and the remainder received saline (0.9% NaCl) solution IM. All cats received meloxicam (0.2 mg/kg, SC) immediately prior to the conclusion of surgery. RESULTS: All drug combinations induced lateral recumbency, and intubation was achievable in 13 of 30 (43%) cats at 10 minutes after injection. Supplemental isoflurane was needed for the surgery in 1 of 10 of the DKBut-, 2 of 10 of the DKH-, and 7 of 10 of the DKBup-treated cats. Cats that received atipamezole had a significantly shorter recovery time. CONCLUSIONS AND CLINICAL RELEVANCE: DKBut and DKH combinations were suitable injectable anesthetic protocols for castration in cats commencing at 10 minutes after injection, but cats receiving DKBup may require additional time or anesthetics for adequate anesthesia.