Objective—To evaluate bispectral index (BIS), spectral
edge frequency 95% (SEF), and median frequency
(MED) in relation to a visual analogue scale (VAS)
as indicators of anesthetic depth for various concentrations
of sevoflurane and isoflurane in pigs.
Procedure—Pigs were randomly allocated to 8 groups
(4 pigs/group). An electroencephalogram (EEG) was
recorded in each conscious pig. Pigs were then anesthetized
by use of sevoflurane (n = 16) or isoflurane
(16). Agents were administered in oxygen at minimum
alveolar concentrations (MACs) of 1, 1.25, 1.5, and 1.75
MAC in a randomized order. End-tidal sevoflurane and
isoflurane concentrations were maintained for 30 minutes,
after which an EEG was recorded for 5 minutes;
BIS, SEF, and MED were then calculated. Anesthetic
depth was evaluated by use of the VAS. Cardiovascular
and EEG responses to nociceptive stimuli were evaluated
for each anesthetic agent.
Results—BIS decreased significantly for the various
concentrations of each anesthetic. At equivalent
MACs, BIS values were significantly higher during
sevoflurane-induced anesthesia than during isoflurane-
induced anesthesia. Values of MED and SEF
decreased significantly from basal values to 1 MAC of
sevoflurane and isoflurane. For both agents, there
was good correlation between VAS scores and BIS
values and between VAS scores and SEF values.
Conclusions and Clinical Relevance—BIS was useful
for predicting changes in anesthetic depth at clinical
dosages of inhalant anesthetics. Values of BIS,
SEF, and MED were significantly higher during anesthesia
induced by administration of sevoflurane than
during anesthesia induced by administration of isoflurance
at equivalent MACs. (Am J Vet Res 2003;64:866–873)
Objective—To identify epidemiological trends in cutaneous neoplasms affecting equids in central North America and compare them with previously reported trends.
Design—Retrospective case series.
Sample—3,351 cutaneous biopsy specimens from 3,272 equids with a neoplastic diagnosis.
Procedures—Diagnostic reports from 2 diagnostic laboratories (Colorado State University and Prairie Diagnostic Services Inc) were reviewed for frequency of specific lesions and epidemiological trends. Variables included in analyses (if known) were age, sex, breed, geographic location, date of diagnosis, location of neoplasm on the body, and presence or absence of ulceration.
Results—Sarcoid, squamous cell carcinoma (SCC), and melanoma were the 3 most common tumors diagnosed. Tumors associated with UV radiation (SCC, SCC in situ, hemangioma, hemangiosarcoma) were 2.3 (95% confidence interval [CI], 1.8 to 3.0) times as common in biopsy specimens received by Colorado State University than in specimens received by Prairie Diagnostic Services Inc. Appaloosa horses and American Paint horses, respectively, were 7.2 (95% CI, 5.6 to 9.2) and 4.4 (95% CI, 3.6 to 5.4) times as likely as other breeds to have tumors associated with UV radiation. Thoroughbreds were predisposed to cutaneous lymphoma, whereas Arabians were more likely to have melanomas. Draft and pony breeds were 3.1 (95% CI, 1.9 to 5.1) times as likely as other breeds to have benign soft tissue tumors. Morgans and pony breeds more commonly had basal cell tumors. Tumors in the perianal region were significantly more likely to be SCC or melanoma while tumors on the limbs were more likely to be giant cell tumor of soft parts.
Conclusions and Clinical Relevance—Signalment, anatomic location of the mass, and geographic location of the horse can be used to help equine practitioners formulate differential diagnoses for cutaneous masses. Further research is necessary to identify the biological basis for the development of many equine cutaneous neoplasms.