To compare the speed of onset and analgesic effect of mepivacaine deposited within or immediately outside the neurovascular bundle at the base of the proximal sesamoid bones in horses.
6 horses with naturally occurring forefoot-related lameness.
In a crossover study design, horses were randomly assigned to receive 1 of 2 treatments first, with the second treatment administered 3 to 7 days later. Trotting gait was analyzed with an inertial sensor–based motion analysis system immediately before treatment to determine degree of lameness. Afterward, ultrasound guidance was used to inject 2% mepivacaine hydrochloride around the palmar digital nerves of the affected forelimb at the level of the base of the proximal sesamoid bones either within the subcircumneural space or outside the circumneural sheath. After injection, gait was reevaluated at 5-minute intervals for 45 minutes.
Mepivacaine deposition outside the circumneural sheath did not resolve lameness in any horse; for 3 horses, the mean time to 70% reduction of initial vertical head movement was 13.3 minutes, and the remaining 3 horses had no such reduction at any point. Mepivacaine deposition within the subcircumneural space resulted in a mean time to 70% reduction of initial vertical head movement of 6.7 minutes and mean time to resolution of lameness of 21.7 minutes.
CONCLUSIONS AND CLINICAL RELEVANCE
Results suggested that when peripheral nerves of horses lie within a sheath, local anesthetic solution should be deposited within the sheath for an effective nerve block. If local anesthetic solution is deposited outside the sheath, the nerve block may yield erroneous results.
Objective—To evaluate the elimination kinetics of
chlorhexidine in milk when used as an intramammary
infusion to stop lactation in cows.
Procedure—The study was performed in 2 phases.
Three cows were studied in each phase. All cows were
treated with chlorhexidine suspension by infusion into a
mastitic mammary gland quarter after 2 milkings 24
hours apart. Foremilk samples (100 mL) were collected
from treated and untreated (controls) mammary gland
quarters of each cow. Chlorhexidine was extracted from
raw milk, and residue concentrations were quantified by
use of high-performance liquid chromatography.
Foremilk samples from days 2, 5, and 8 were analyzed
in phase I, and samples from time 0 and days 3, 7, 14,
21, 28, 35, and 42 were analyzed in phase II.
Results—In phases I and II, there was no quantifiable
transference of chlorhexidine to milk in untreated
mammary gland quarters. Measurable chlorhexidine
residues were found in milk from treated mammary
gland quarters of 2 cows throughout the 42-day sample
period in phase II. Estimated mean elimination
half-life for chlorhexidine in milk was 11.5 days.
Conclusions and Clinical Relevance—On the basis of
the long elimination half-life of chlorhexidine in milk
from treated mammary gland quarters, the lack of
human dietary exposure data to suggest a food tolerance
for chlorhexidine in food products, and the Food
and Drug Administration's published zero tolerance for
chlorhexidine in uncooked edible calf tissues, we do not
recommend extralabel use of chlorhexidine suspension
as a treatment to stop lactation in mastitic mammary
gland quarters of cows. (J Am Vet Med Assoc 2003;
OBJECTIVE To determine brain region affinity for and retention of gadolinium in dogs after administration of gadodiamide and whether formalin fixation affects quantification.
ANIMALS 14 healthy dogs.
PROCEDURES 13 dogs received gadodiamide (range, 0.006 to 0.1 mmol/kg, IV); 1 control dog received a placebo. Dogs received gadodiamide 3 to 7 days (n = 8) or 9 hours (5) before euthanasia and sample collection. Brain regions were analyzed with inductively coupled mass spectrometry (ICP-MS) and transmission electron microscopy. Associations between dose, time to euthanasia, and gadolinium retention quantities (before and after fixation in 5 dogs) were evaluated.
RESULTS Gadolinium retention was seen in all brain regions at all doses, except for the control dog. Exposure 3 to 7 days before euthanasia resulted in 1.7 to 162.5 ng of gadolinium/g of brain tissue (dose-dependent effect), with cerebellum, parietal lobe, and brainstem affinity. Exposure 9 hours before euthanasia resulted in 67.3 to 1,216.4 ng of gadolinium/g of brain tissue without dose dependency. Transmission electron microscopy revealed gadolinium in examined tissues. Fixation did not affect quantification in samples immersed for up to 69 days.
CONCLUSIONS AND CLINICAL RELEVANCE Gadodiamide exposure resulted in gadolinium retention in the brain of healthy dogs. Cerebellum, parietal lobe, and brainstem affinity was detected with dose dependency only in dogs exposed 3 to 7 days before euthanasia. Fixation had no effect on quantification when tissues were immersed for up to 69 days. Physiologic mechanisms for gadolinium retention remained unclear. The importance of gadolinium retention requires further investigation.
Objective—To compare antibody responses, feedlot morbidity and mortality rates, feedlot performance, and carcass value for calves vaccinated with 1 of 2 vaccination strategies and for unvaccinated control calves.
Design—Randomized controlled clinical trial.
Animals—451 beef steers and heifers.
Procedures—Calves were vaccinated with a modified-live infectious bovine rhinotracheitis virus (IBRV), bovine viral diarrhea virus types 1 (BVDV1) and 2 (BVDV2), parainfluenza type 3 virus, and bovine respiratory syncytial virus vaccine and Mannheimia haemolytica and Pasteurella multocida bacterin-toxoid at approximately 67 and 190 days of age (group 1; n = 151) or at approximately 167 and 190 days of age (group 2; 150) or were not vaccinated (control; 150). Serum antibody titers were measured at approximately 2, 67, 167, 190, and 232 days of age. Morbidity and mortality rates, feedlot performance, and carcass value were recorded for 361 calves shipped to feedlots.
Results—Percentages of calves seroconverting to IBRV, BVDV1, and BVDV2 were significantly higher for groups 1 and 2 than for the control group. Mean treatment costs were significantly lower for vaccinated than for control calves, and mean mortality rate was significantly higher for control calves than for group 1 calves. Feedlot performance and carcass value did not vary significantly among groups.
Conclusions and Clinical Relevance—Results suggested that vaccination of beef calves with a 5-antigen modified-live virus vaccine at 67 and 190 days of age was as effective in terms of immunologic responses as was vaccination at 167 and 190 days of age.
Objective—To determine whether heavy (≥ 680 kg [≥ 1,500 lb]) draft horses undergoing surgical treatment for acute signs of abdominal pain were at a greater risk for anesthetic and postoperative complications and lower postoperative survival rates than light (< 680 kg) draft horses.
Design—Retrospective case series.
Animals—72 draft horses.
Procedures—Medical records of draft horses that underwent exploratory celiotomy for signs of acute abdominal pain from October 1983 to December 2002 were reviewed. Medical records of draft horses in which a celiotomy was performed for correction of reproductive abnormalities were not included in the study.
Results—When compared with light draft horses, heavy draft horses had longer durations of anesthesia, more postoperative complications, and lower survival rates. Seventy-six percent of horses that recovered from anesthesia had postoperative complications. Postoperative complications associated with low survival rates included myopathy and neuropathy, ileus, diarrhea, and endotoxemia. All horses with postoperative myopathy and neuropathy died or were euthanized. The short-term survival rate for horses that recovered from anesthesia was 60%. Horses undergoing small intestinal surgery had a worse prognosis for short-term survival than those undergoing large intestinal surgery. The survival rate for horses for which long-term (> 1 year) follow-up information was available was 50%.
Conclusions and Clinical Relevance—Draft horses weighing > 680 kg that underwent surgery because of acute signs of abdominal pain had longer durations of anesthesia, more postoperative complications, and higher mortality rates than draft horses weighing < 680 kg.
Objective—To evaluate sensitivities at the herd level
of test strategies used in the Voluntary Johne's
Disease Herd Status Program (VJDHSP) and alternative
test strategies for detecting dairy cattle herds
infected with Mycobacterium paratuberculosis.
Design—Nonrandom cross-sectional study.
Sample Population—64 dairy herds from
Pennsylvania, Minnesota, Colorado, Ohio, and
Wisconsin. Fifty-six herds had at least 1 cow shedding
M paratuberculosis in feces; the other 8 herds
were free from paratuberculosis.
Procedure—For all adult cows in each herd, serum
samples were tested for antibodies to M paratuberculosis with
an ELISA, and fecal samples were submitted
for bacterial culture for M paratuberculosis. Sensitivities
at the herd level (probability of detecting infected herd)
of various testing strategies were then evaluated.
Results—Sensitivity at the herd level of the testing
strategy used in level 1 of the VJDHSP (use of the
ELISA to test samples from 30 cows followed by confirmatory
bacterial culture of feces from cows with
positive ELISA result) ranged from 33 to 84% for
infected herds, depending on percentage of cows in
the herd with positive bacterial culture results. If follow-
up bacterial culture was not used to confirm positive
ELISA results, sensitivity ranged from 70 to
93%, but probability of identifying uninfected herds
as infected was 89%.
Conclusions and Clinical Relevance—Results suggest
that the testing strategy used in the VJDHSP will
fail to identify as infected most dairy herds with a low
prevalence of paratuberculosis. A higher percentage
of infected herds was detected if follow-up bacterial
culture was not used, but this test strategy was associated
with a high probability of misclassifying uninfected
herds. (J Am Vet Med Assoc 2002;220: 1053–1057)