Objective—To determine whether moderate
hypothermia during 4 hours of anesthesia with isoflurane
substantially affects serum concentrations of
transdermally administered fentanyl in the perianesthetic
period in cats.
Animals—7 healthy mature cats.
Procedure—A fentanyl patch (25 µg/h) was applied to
the shaved thorax 24 hours before induction of anesthesia.
Anesthesia was induced at time 0. Each cat
received 2 treatments in a random order. Treatments
were isoflurane anesthesia with normothermia and
isoflurane anesthesia with hypothermia. Cats were
intubated, connected to a nonrebreathing circuit, and
maintained at 1.3X minimum alveolar concentration
for 4 hours. Cats in the hypothermia treatment groups
were actively cooled to 35°C following the induction
of anesthesia. Serum fentanyl analysis was performed
at –24, –12, 0, 1, 2, 3, 4, 4.5, 5, 6, 7, 8, 9, 10,
12, and 24 hours.
Results—Mean ± SEM serum fentanyl concentration
(SFC) for the hypothermia treatment group (0.598 ±
0.3048 ng/mL) was significantly lower than the baseline
concentration (1.834 ± 0.6393 ng/mL) at 1 hour.
This significant reduction persisted for the duration of
anesthesia for the hypothermia treatment group.
Serum fentanyl concentrations returned to baseline
values within 1 hour of the end of anesthesia, regardless
of body temperature.
Conclusions and Clinical Relevance—Hypothermia
during inhalant anesthesia induced a significant
reduction in SFC obtained with transdermal administration.
The impact of this reduction in SFC on the
contribution of transdermally administered fentanyl to
any reduction in the need for inhalant anesthesia
remains to be determined. (Am J Vet Res 2003;64:1557–1561)
To describe a technique for circumferential esophageal hiatal rim reconstruction and to report outcomes in brachycephalic dogs with persistent regurgitation treated with the technique.
29 client-owned brachycephalic dogs.
Dogs that had undergone circumferential esophageal hiatal rim reconstruction between January 1, 2016, and December 31, 2019, for treatment of persistent regurgitation were identified through a search of the medical record database of The Animal Hospital at Murdoch University. Circumferential esophageal hiatal rim reconstruction involved apposition of the medial margins of the left and right pars lumbalis dorsal to the esophagus (reconstructing the dorsal margin) and ventral to the esophagus (reducing the ventral hiatal aperture and completing the circumferential reconstruction). Data collection from the medical records included preoperative, intraoperative, and postoperative (short- and long-term outcomes [≤ 14 days and ≥ 6 months, respectively]) data.
In all dogs, substantial laxity of the left and right pars lumbalis and failure of dorsal coaxial alignment were observed, and circumferential esophageal hiatal rim reconstruction and esophagopexy were performed. Results of short-term follow-up indicated reduced regurgitation frequency; however, 7 of 29 dogs continued to have mild regurgitation, which was attributed to esophagitis and resolved with medical management. Long-term follow-up information was available for 19 dogs: regurgitation had resolved in 16 dogs and occurred once weekly in 3 dogs. No ongoing medication was required for any dog.
CONCLUSIONS AND CLINICAL RELEVANCE
Circumferential hiatal rim reconstruction combined with esophagopexy substantially reduced regurgitation frequency in dogs of the present study, and we recommend that this procedure be considered for brachycephalic dogs presented with a history of regurgitation unresponsive to medical management.
OBJECTIVE To measure changes in interleukin-8 (IL-8), interleukin-1β (IL-1β), and tumor necrosis factor-α (TNF-α) concentrations in stored canine packed RBCs (PRBCs) over time and assess the effect of leukoreduction on these cytokine concentrations.
ANIMALS 12 anesthetized healthy Greyhounds.
PROCEDURES 1 unit of whole blood from each dog was processed into PRBCs. Half of each PRBCs unit was passed through a leukoreduction filter to produce a leukoreduced unit, and the remaining blood was kept as a nonleukoreduced unit. All units had a CBC performed on day 0 (day of collection) and were stored at 2° to 6°C. Samples were collected from leukoreduced and nonleukoreduced units on days 0, 10, 20, 30, and 37 and centrifuged; the supernatant was stored at −80°C until analysis. Canine TNF-α and IL-8 concentrations were assessed with a multiplexed genomic and proteomic biomarker analyzer, and canine IL-1β concentration was measured by ELISA.
RESULTS Leukocyte counts were decreased by ≥ 99.9% in all leukoreduced units. Median TNF-α and IL-1β concentrations were not significantly different between leukoreduced and nonleukoreduced units and did not change significantly during storage; median IL-8 concentration was significantly higher in nonleukoreduced versus leukoreduced units on all days, and was greater at all time points after ≥ 10 days of storage than on day 0. Median IL-8 concentration in leukoreduced units did not increase during storage.
CONCLUSIONS AND CLINICAL RELEVANCE Results indicated that leukoreduction was effective for the removal of leukocytes from canine PRBCs and prevented significant increases in IL-8 concentration during storage. Further studies are needed to evaluate whether leukoreduction reduces cytokine-associated complications of transfusion.
Procedure—Dogs received each of 4 treatments in random order. Following induction of anesthesia, normothermia was maintained in dogs that were treated with a fentanyl patch (F-NORM) or sham patch (C-NORM), or hypothermia was maintained in dogs that were treated with a fentanyl patch (F-HYPO) or sham patch (C-HYPO). The appropriate patch was applied 24 hours prior to induction of anesthesia. Anesthesia was induced with isoflurane in oxygen; the dogs were intubated and mechanically ventilated. Target esophageal temperatures were maintained within 1°C of baseline values (normothermia) or at 34.5°C (94.1°F; hypothermia) for 1 hour prior to starting MAC determinations. Supramaximal stimulation was achieved with an electrical stimulator attached to needle electrodes placed in the buccal mucosa of the lower jaw of the dog.
Results—Mean MAC ± SEM of isoflurane during C-NORM, C-HYPO, F-NORM, and F-HYPO treatments were 1.20 ± 0.17, 0.89 ± 0.18, 0.76 ± 0.10, and 0.81 ± 0.17, respectively. The mean MAC during C-NORM was significantly higher than values for the other treatments. There was no significant difference in mean MAC among the C-HYPO, F-NORM, and F-HYPO treatments.
Conclusions and Clinical Relevance—Data suggest that transdermal administration of fentanyl significantly reduces isoflurane requirements in normothermic dogs. The isoflurane MAC-sparing effects of transdermal fentanyl are not apparent in hypothermic dogs.
To describe the application and owner experience of tube cystostomy for management of upper motor neuron urinary bladder dysfunction secondary to intervertebral disk extrusion (IVDE) or ischemic myelopathy, and to report complications associated with cystostomy tube management.
Medical records of dogs with IVDE or ischemic myelopathy cranial to the L3 spinal cord segment that underwent tube cystostomy placement via a short, caudal ventral midline celiotomy were reviewed. Days from tube placement to hospital discharge, days from placement to tube removal, and complications were recorded. An owner questionnaire was distributed to ascertain ease of use and perceived time commitment.
58 dogs were diagnosed with IVDE, and 3 dogs were diagnosed with ischemic myelopathy. The modal neurologic grade at cystostomy tube placement was 4 (range, 3 to 5). The median number of days from cystostomy tube placement to hospital discharge was 1 (range, 0 to 3). Follow-up data was available for 56 dogs. The median number of days from cystostomy tube placement until removal was 19 (range, 3 to 74). Fifteen minor and 6 severe postoperative complications were reported, mainly inadvertent removal (n = 11) and peristomal urine leakage (6). Twenty-seven owners responded to the questionnaire and primarily reported that cystostomy tube use was easy (22/27) and perceived time commitment was low or minimal (20/27).
Tube cystostomy facilitates early hospital discharge and allows at-home, extended urinary management in dogs recovering from upper motor neuron urinary bladder dysfunction secondary to IVDE or ischemic myelopathy. This technique is simple for owners to use.
Objective—To characterize the in vitro effects of
oxytocin, acepromazine, xylazine, butorphanol,
detomidine, dantrolene, isoproterenol, and terbutaline
on skeletal and smooth muscle from the
Animals—14 adult horses without digestive tract disease.
Procedure—Circular and longitudinal strips from
the skeletal and smooth muscle of the esophagus
were suspended in tissue baths, connected to
force-displacement transducers interfaced with a
physiograph, and electrical field stimulation was
applied. Cumulative concentration-response curves
were generated for oxytocin, acepromazine,
xylazine, detomidine, butorphanol, isoproterenol,
terbutaline, and dantrolene. Mean maximum twitch
amplitude for 3 contractions/min was recorded and
compared with predrug-vehicle values for the
skeletal muscle segments, and area under the
curve (AUC) for 3 contractions/min was compared
with predrug-vehicle values for the smooth muscle
Results—No drugs caused a significant change in
skeletal muscle response. In smooth muscle, isoproterenol,
terbutaline, and oxytocin significantly
reduced AUC in a concentration-dependent manner.
Maximum reduction in AUC was 69% at 10–4M for
isoproterenol, 63% at 10–5M for terbutaline, and
64% at 10–4M for oxytocin.
Conclusions and Clinical Relevance—Isoproterenol,
terbutaline, and oxytocin cause relaxation of the
smooth muscle portion of the esophagus. The clinical
relaxant effects on the proximal portion of the esophagus
reported of drugs such as oxytocin, detomidine,
and acepromazine may be the result of centrally mediated
mechanisms. (Am J Vet Res 2002;63:1732–1737)
Objective—To compare effects of oxytocin, acepromazine
maleate, xylazine hydrochloride-butorphanol
tartrate, guaifenesin, and detomidine hydrochloride
on esophageal manometric pressure in horses.
Animals—8 healthy adult horses.
Procedure—A nasogastric tube, modified with 3
polyethylene tubes that exited at the postpharyngeal
area, thoracic inlet, and distal portion of the
esophagus, was fitted for each horse. Amplitude,
duration, and rate of propagation of pressure waveforms
induced by swallows were measured at 5, 10,
20, 30, and 40 minutes after administration of oxytocin,
detomidine, acepromazine, xylazine-butorphanol,
guaifenesin, or saline (0.9% NaCl) solution.
Number of spontaneous swallows, spontaneous
events (contractions that occurred in the absence of
a swallow stimulus), and high-pressure events (sustained
increases in baseline pressure of > 10 mm
Hg) were compared before and after drug administration.
Results—At 5 minutes after administration, detomidine
increased waveform amplitude and decreased
waveform duration at the thoracic inlet. At 10 minutes
after administration, detomidine increased waveform
duration at the thoracic inlet. Acepromazine administration
increased the number of spontaneous events
at the thoracic inlet and distal portion of the esophagus.
Acepromazine and detomidine administration
increased the number of high-pressure events at the
thoracic inlet. Guaifenesin administration increased
the number of spontaneous events at the thoracic
inlet. Xylazine-butorphanol, detomidine, acepromazine,
and guaifenesin administration decreased the
number of spontaneous swallows.
Conclusions and Clinical Relevance—Detomidine,
acepromazine, and a combination of xylazine butorphanol
had the greatest effect on esophageal motility
when evaluated manometrically. Reduction in spontaneous
swallowing and changes in normal, coordinated
peristaltic activity are the most clinically relevant
effects. (Am J Vet Res 2002;63:1738–1744)
Objective—To describe the pharmacokinetics of
cyclosporine (CyA) in healthy dogs after oral administration
alone or in combination with orally administered
Animals—10 healthy adult Beagles.
Procedure—Dogs were randomly assigned to
receive CyA alone or CyA in combination with cimetidine.
After a washout period of 2 weeks, dogs then
received the alternate treatment. The CyA plus cimetidine
treatment required administration of cimetidine
(15 mg/kg of body weight, PO, q 8 h) for 8 days and
administration of CyA (5 mg/kg, PO, q 24 h) on days
6 through 8. The CyA treatment alone required
administration of CyA (5 mg/kg, PO, q 24 h) for 3
days. On the third day of CyA administration during
each treatment, blood samples were collected immediately
before (time 0) and 0.5, 1, 1.5, 2, 2.5, 3, 5, 7,
9, 11, 13, 15, 21, and 24 hours after initiating CyA
Results—Time until maximum CyA concentration
was significantly longer for CyA in combination with
cimetidine. Assessment of estimated pharmacokinetic
variables revealed a significantly faster rate of
change in the distribution phase for CyA in combination
with cimetidine. Maximum CyA concentration
differed significantly among dogs but did not differ
significantly between treatments.
Conclusions and Clinical Relevance—Analysis of
our data suggests that cimetidine may affect absorption
of orally administered CyA, but overall, it does
not affect the pharmacokinetics of CyA. There is considerable
variability in the maximum concentration of
CyA among dogs, and monitoring of blood concentrations
of CyA during treatment is advised. (Am J Vet
Objective—To assess the relationship between body weight and gastrointestinal transit times measured by use of a wireless motility capsule (WMC) system in healthy dogs.
Animals—31 healthy adult dogs that weighed between 19.6 and 81.2 kg.
Procedures—Food was withheld overnight. The following morning, a WMC was orally administered to each dog, and each dog was then fed a test meal that provided a fourth of the daily energy requirements. A vest was fitted on each dog to hold a receiver that collected and stored data from the WMC. Measurements were obtained with each dog in its home environment. Regression analysis was used to assess the relationship between body weight and gastrointestinal transit times.
Results—Gastric emptying time (GET) ranged from 405 to 897 minutes, small bowel transit time (SBTT) ranged from 96 to 224 minutes, large bowel transit time (LBTT) ranged from 427 to 2,573 minutes, and total transit time (TTT) ranged from 1,294 to 3,443 minutes. There was no positive relationship between body weight and gastrointestinal transit times. A nonlinear inverse relationship between body weight and GET and between body weight and SBTT best fit the data. The LBTT could not be explained by this model and likely influenced the poor fit for the TTT.
Conclusions and Clinical Relevance—A positive relationship did not exist between body weight and gastrointestinal transit times. Dogs with the lowest body weight of the cohort appeared to have longer gastric and small intestinal transit times than did large- and giant-breed dogs.