CASE DESCRIPTION 4 dogs were examined because of pleural effusion and ventricular tachycardia, coughing and supraventricular tachycardia, appendicular osteosarcoma, and syncopal episodes.
CLINICAL FINDINGS In all 4 dogs, a heart base tumor was identified by means of thoracic CT.
TREATMENT AND OUTCOME In all 4 dogs, the heart base tumors were treated by means of stereotactic body radiation therapy. Dogs were anesthetized, and neuromuscular blockade was achieved with atracurium or vecuronium. A circle rebreathing system with 15 m (50 feet) of anesthetic tubing coursing through the vault wall was used to connect the patient to the anesthesia machine, which was located in the control room. After a brief period of hyperventilation, an inspiratory breath was held at 20 cm H2O for the duration of beam delivery. Each beam delivery lasted between 30 and 100 seconds. Immediately following the breath hold, assisted ventilation was resumed. Mean treatment delivery time for each patient was 26 minutes; mean total anesthesia time was 89 minutes. All patients recovered without complications. There was no evidence of hemoglobin desaturation or hypercapnia during the anesthetic procedure.
CLINICAL RELEVANCE The technique allowed for control of the respiration cycle from outside the radiation vault and a short overall treatment time. No adverse effects were encountered. This procedure should be considered when delivering radiation to structures within the thoracic cavity.
Objective—To evaluate effects of maropitant, acepromazine, and electroacupuncture on morphine-related signs of nausea and vomiting in dogs and assess sedative effects of the treatments.
Design—Randomized controlled clinical trial.
Procedures—Dogs received 1 of 6 treatments: injection of saline (0.9% NaCl) solution, maropitant citrate, or acepromazine maleate or electroacupuncture treatment at 1 acupoint, 5 acupoints, or a sham acupoint. Morphine was administered after 20 minutes of electroacupuncture treatment or 20 minutes after injectable treatment. Vomiting and retching events and signs of nausea and sedation were recorded.
Results—Incidence of vomiting and retching was significantly lower in the maropitant (14/37 [37.8%]) group than in the saline solution (28/37 [75.7%]) and sham-acupoint electroacupuncture (32/37 [86.5%]) groups. The number of vomiting and retching events in the maropitant (21), acepromazine (38), 1-acupoint (35), and 5-acupoint (34) groups was significantly lower than in the saline solution (88) and sham-acupoint electroacupuncture (109) groups. Incidence of signs of nausea was significantly lower in the acepromazine group (3/37 [8.1%]) than in the sham-acupoint group (15/37 [40.5%]). Mean nausea scores for the saline solution, maropitant, and sham-acupoint electroacupuncture groups increased significantly after morphine administration, whereas those for the acepromazine, 1-acupoint electroacupuncture, and 5-acupoint electroacupuncture groups did not. Mean sedation scores after morphine administration were significantly higher in dogs that received acepromazine than in dogs that received saline solution, maropitant, and sham-acupoint electroacupuncture treatment.
Conclusions and Clinical Relevance—Maropitant treatment was associated with a lower incidence of vomiting and retching, compared with control treatments, and acepromazine and electroacupuncture appeared to prevent an increase in severity of nausea following morphine administration in dogs.
Objective—To determine and compare the effects of caffeine and doxapram on cardiorespiratory variables in foals during isoflurane-induced respiratory acidosis.
Animals—6 clinically normal foals (1 to 3 days old).
Procedures—At intervals of ≥ 24 hours, foals received each of 3 IV treatments while in a steady state of hypercapnia induced by isoflurane anesthesia (mean ± SD, 1.4 ± 0.3% endtidal isoflurane concentration). After assessment of baseline cardiorespiratory variables, a low dose of the treatment was administered and variables were reassessed; a high dose was then administered, and variables were again assessed. Sequential low- and high-dose treatments included doxapram (loading dose of 0.5 mg/kg, followed by a 20-minute infusion at 0.03 mg/kg/min and then 0.08 mg/kg/min), caffeine (5 mg/kg and 10 mg/kg), and saline (0.9% NaCl) solution (equivalent volumes).
Results—Administration of doxapram at both infusion rates resulted in a significant increase in respiratory rate, minute ventilation, arterial blood pH, PaO2, and arterial blood pressure. These variables were also significantly higher during doxapram administration than during caffeine or saline solution administration. There was a significant dose-dependent decrease in PaCO2 and arterial bicarbonate concentration during doxapram treatment. In contrast, PaCO2 increased from baseline values after administration of saline solution or caffeine. The PaCO2 value was significantly lower during doxapram treatment than it was during caffeine or saline solution treatment.
Conclusions and Clinical Relevance—Results indicated that doxapram restored ventilation in a dose-dependent manner in neonatal foals with isoflurane-induced hypercapnia. The effects of caffeine on respiratory function were indistinguishable from those of saline solution.
Objective—To compare cardiac output (CO) measured by lithium arterial pressure waveform analysis (PULSECO) and CO measured by transpulmonary pulse contour analysis (PICCO) in anesthetized foals, with CO measured by use of lithium dilution (LIDCO) considered the criterion-referenced standard.
Sample Population—6 neonatal (1- to 4-day-old) foals that weighed 38 to 45 kg.
Procedures—Foals were anesthetized and instrumented to measure direct blood pressure, heart rate, arterial blood gases, and CO. The CO was measured by use of PULSECO, PICCO, and LIDCO techniques. Measurements were converted to specific CO (sCO) values for statistical analysis. Measurements were obtained during low, intermediate, and high CO states.
Results—sCO ranged from 75.5 to 310 mL/kg/min. Mean ± SD PICCO bias varied significantly among CO states and was −51.9 ± 23.1 mL/kg/min, 20.0 ± 19.5 mL/kg/min, and 87.2 ± 19.5 mL/kg/min at low, intermediate, and high CO states, respectively. Mean PULSECO bias (11.0 ± 37.5 mL/kg/min) was significantly lower than that of PICCO and did not vary among CO states. Concordance correlation coefficient between LIDCO and PULSECO was significantly greater than that between LIDCO and PICCO. The proportion of observations with a relative bias < ± 30% was significantly lower with the PULSECO method than with the PICCO method.
Conclusions and Clinical Relevance—Values for the PULSECO method were more reproducible and agreed better with values for the LIDCO method than did values for the PICCO method and were able to more accurately monitor changes in CO in anesthetized newborn foals.
PROCEDURES Baseline rectal temperature, heart rate, and respiratory rate were recorded prior to premedication with buprenorphine (0.02 mg/kg, IM) and acepromazine (0.05 mg/kg, IM). Anesthesia was induced with midazolam or diazepam (0.25 mg/kg, IV) plus ketamine (5 mg/kg, IV; n = 11) or propofol (4 mg/kg, IV; 12) and maintained with isoflurane in oxygen. Rectal temperature was measured at hospital intake, prior to premedication, immediately after anesthetic induction, and every 5 minutes after anesthetic induction. Esophageal temperature was measured every 5 minutes during anesthesia, beginning 30 minutes after anesthetic induction. After anesthesia, dogs were covered with a warm-air blanket and rectal temperature was measured every 10 minutes until normothermia (37°C) was achieved.
RESULTS Dogs in both treatment groups had lower rectal temperatures within 5 minutes after anesthetic induction and throughout anesthesia. Compared with dogs that received a benzodiazepine plus ketamine, dogs that received a benzodiazepine plus propofol had significantly lower rectal temperatures and the interval from discontinuation of anesthesia to achievement of normothermia was significantly longer.
CONCLUSIONS AND CLINICAL RELEVANCE Dogs in which anesthesia was induced with a benzodiazepine plus propofol or ketamine became hypothermic; the extent of hypothermia was more profound for the propofol combination. Dogs should be provided with adequate heat support after induction of anesthesia, particularly when a propofol-benzodiazepine combination is administered.
Objective—To evaluate the use of the anesthetic
combination tiletamine, zolazepam, ketamine, and
xylazine (TKX) for anesthesia of feral cats at largescale
Animals—7,502 feral cats.
Procedure—Cats were trapped by their caretakers
for a feral cat neutering program from July 1996 to
August 2000. The anesthetic combination TKX was
injected IM into cats while they remained in their
traps. Each milliliter of TKX contained 50 mg of tiletamine,
50 mg of zolazepam, 80 mg of ketamine, and
20 mg of xylazine. Females were spayed by veterinarians,
whereas males were castrated by veterinarians
or veterinary students. Yohimbine (0.5 mg, IV)
was administered at the end of the procedure. Logs
were kept of the individual drug doses, signalment of
the cats, and any complications encountered. These
data were analyzed retrospectively (1996 to 1999)
and prospectively (2000).
Results—Of the 5,766 cats for which dosing records
were complete, 4,584 (79.5%) received a single
dose of TKX. The mean initial dose of TKX was 0.24
± 0.04 ml/cat, and the total mean dose of TKX was
0.27 ± 0.09 ml. Overall mortality rate was 0.35%
(26/7,502) cats, and the death rate attributable solely
to potential anesthetic deaths was 0.23% (17/7,502)
Conclusions and Clinical Relevance—The use of TKX
for large-scale feral cat neutering clinics has several
benefits. The TKX combination is inexpensive, provides
predictable results, can be administered quickly and
easily in a small volume, and is associated with a low
mortality rate in feral cats. (J Am Vet Med Assoc 2002;
Objective—To evaluate the effect of cold compression therapy (CCT) on postoperative pain, lameness, range of motion of the stifle joint, and swelling following tibial plateau leveling osteotomy (TPLO) in dogs.
Animals—34 client-owned dogs with unilateral deficiency of a cranial cruciate ligament undergoing TPLO.
Procedures—Dogs were assigned to 2 groups. Group 1 (n = 17 dogs) received CCT in the 24-hour period following TPLO. Group 2 (n = 17 dogs) received no CCT. Degree of lameness, range of motion, and circumference of the stifle joint were measured before surgery and 1,14, and 28 days after surgery. A modified composite Glasgow pain scale, visual analogue scale, and pain threshold score were used to evaluate signs of pain before surgery and 1,14, and 28 days after surgery. Logistic regression and linear regression analysis were used to compare the measured variables.
Results—No complications were observed, and all dogs tolerated CCT. Use of CCT resulted in lower values for the visual analogue scale and Glasgow pain scale and lower pain threshold scores; lower lameness scores; less swelling; and an increased range of motion 24 hours after surgery. At 14 days after surgery, there were no significant differences between groups. At 28 days after surgery, too few data sets were available for comparison.
Conclusions and Clinical Relevance—CCT decreased signs of pain, swelling, and lameness and increased stifle joint range of motion in dogs during the first 24 hours after TPLO.