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.
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.
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.
Objective—To determine whether dilution of blood samples from healthy dogs with 2 hydroxyethyl starch (HES) solutions, HES 130/0.4 and HES 200/0.5, would result in platelet dysfunction as measured by closure time (Ct) beyond a dilutional effect.
Sample—Citrated blood samples from 10 healthy dogs with a Ct within reference limits (52 to 86 seconds).
Procedures—Blood samples were diluted 1:9 and 1:3 with 6% HES 130/0.4 and 10% HES 200/0.5 solutions and saline (0.9% NaCl) solution. Dilutions at 1:9 and 1:3 mimicked 10 mL/kg and 30 mL/kg doses, respectively, ignoring in vivo redistribution. Closure time was measured with a platelet function analyzer and compared among dilutions.
Results—A dilutional effect on Ct was evident for the 1:3 dilution, compared with the 1:9 dilution, but only HES 200/0.5 increased the Ct beyond the dilutional effect at the 1:3 dilution, to a median Ct of 125 seconds (interquartile range, 117.5 to 139.5 seconds). No effect of HES or dilution on Ct was identified at the 1:9 dilution.
Conclusions and Clinical Relevance—1:3 dilution of blood samples from healthy dogs with HES 200/0.5 but not HES 130/0.4 significantly increased Ct beyond the dilutional effect, suggesting that IV administration of HES 200/0.5 in dogs might cause platelet dysfunction.
Objective—To evaluate the radial growth assay for use in in vitro susceptibility testing of Pythium insidiosum and a Lagenidium sp and to assess susceptibility of representative isolates to itraconazole, posaconazole, voriconazole, terbinafine, caspofungin, and mefenoxam.
Sample Population—6 isolates each of P insidiosum and Lagenidium sp.
Procedures—Isolates were plated in triplicate onto agar supplemented with antifungal compounds at concentrations of 0.025 to 8 μg/mL. Isolates on dimethyl sulfoxide– and water-supplemented agar served as control samples. Effect of antifungal concentration on colony diameter was assessed with a mixed linear model. Assay variability was assessed with the coefficient of variation.
Results—Colony growth was uniform (mean intra-assay and interassay coefficients of variation were < 5%). Minimal inhibition was evident with voriconazole and posaconazole at 8 μg/mL. Terbinafine at 8 μg/mL significantly reduced growth of P insidiosum and at ≥ 1 μg/mL significantly reduced growth of the Lagenidium sp. Caspofungin and mefenoxam (concentrations ≥ 1 μg/mL and ≥ 0.025 μg/mL, respectively) significantly reduced growth of both pathogens. Mefenoxam at 0.1 μg/mL caused > 50% growth inhibition in 11 of 12 isolates and at 1 μg/mL caused > 90% inhibition in all isolates.
Conclusions and Clinical Relevance—Results suggested that the radial growth assay was a simple, reproducible technique for susceptibility testing of P insidiosum and a Lagenidium sp. Azoles had limited activity, whereas terbinafine and caspofungin caused significant but minimal to moderate inhibition. Only mefenoxam had a profound effect on both pathogens at concentrations likely to be achievable in tissues.
Objective—To determine distribution of urokinase plasminogen activator-like protein and urokinase plasminogen activator receptor-like protein in urinary tract tissues of healthy dogs.
Animals—11 healthy dogs.
Procedures—Necropsy specimens from kidney, ureter, bladder, urethra, prostate, and testis were obtained from 4 sexually intact female dogs, 5 sexually intact males, and 2 castrated males; dogs ranged in age from juvenile to adult. Urokinase plasminogen activator-like protein and urokinase plasminogen activator receptor-like protein in tissue lysates from kidney, prostate, and testis were identified by use of SDS-PAGE, western blot analysis, and immunoprecipitation. Urokinase plasminogen activator-like protein and urokinase plasminogen activator receptor-like protein in kidney, ureter, urinary bladder, urethra, prostate, and testis were identified by use of immunohistochemical staining of tissue sections.
Results—Urokinase plasminogen activator-like protein and urokinase plasminogen activator receptor-like protein in the molecular-weight range published for urokinase and urokinase receptor (53 and 33 kd for urokinase and 60 to 65 kd for urokinase receptor) were identified. Distribution of the proteins identified by use of immunohistochemical staining was comparable with published information for humans and mice for the urinary tract. Staining of these proteins was detected in more tissue types than reported in healthy humans.
Conclusions and Clinical Relevance—Urokinase plasminogen activator-like protein and urokinase plasminogen activator receptor-like protein were detected in the urinary tract of healthy dogs. This information is important for further evaluation of the functions of urokinase and urokinase receptor in the canine urinary tract and the pathophysiologic features of urinary tract disease.
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 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