Objective—To determine an infusion rate of butorphanol
tartrate in horses that would maintain therapeutic
plasma drug concentrations while minimizing
development of adverse behavioral and gastrointestinal
Animals—10 healthy adult horses.
Procedure—Plasma butorphanol concentrations
were determined by use of high-performance liquid
chromatography following administration of butorphanol
by single IV injection (0.1 to 0.13 mg/kg of
body weight) or continuous IV infusion (loading dose,
17.8 µg/kg; infusion dosage, 23.7 µg/kg/h for 24
hours). Pharmacokinetic variables were calculated,
and changes in physical examination data, gastrointestinal
tract transit time, and behavior were determined
Results—A single IV injection of butorphanol was
associated with adverse behavioral and gastrointestinal
tract effects including ataxia, decreased borborygmi,
and decreased defecation. Elimination half-life of
butorphanol was brief (44.37 minutes). Adverse gastrointestinal
tract effects were less apparent during
continuous 24-hour infusion of butorphanol at a
dosage that resulted in a mean plasma concentration
of 29 ng/ml, compared with effects after a single IV
injection. No adverse behavioral effects were
observed during or after continuous infusion.
Conclusions and Clinical Relevance—Continuous
IV infusion of butorphanol for 24 hours maintained
plasma butorphanol concentrations within a range
associated with analgesia. Adverse behavioral and
gastrointestinal tract effects were minimized during
infusion, compared with a single injection of butorphanol.
Continuous infusion of butorphanol may be a
useful treatment to induce analgesia in horses. (Am J
Vet Res 2001;62:183–189)
Objective—To determine whether substantial interobserver
variation exists among diagnostic pathologists
for descriptions of intestinal mucosal cell populations
and whether histopathologic descriptions
accurately predict when a patient does not have clinically
evident intestinal disease.
Sample Population—14 histologic slides of duodenal,
ileal, or colonic tissue from 10 dogs and 3
Procedure—Each histologic slide was evaluated
independently by 5 pathologists at 4 institutions.
Pathologists, who had no knowledge of the tissues'
origin, indicated whether slides were adequate for
histologic evaluation and whether the tissue was normal
or abnormal. They also identified the main infiltrating
cell type in specimens that were considered
abnormal, and whether infiltrates were mild, moderate,
severe, or neoplastic.
Results—Quality of all slides was considered adequate
or superior by at least 4 of the 5 pathologists.
For intensity of mucosal cellular infiltrates, there was
uniformity of opinion for 1 slide, near-uniformity for 6
slides, and nonuniformity for 7 slides. Five dogs did
not have clinical evidence of intestinal disease, yet
the pathologists' descriptions indicated that their
intestinal tissue specimens were abnormal.
Conclusions and Clinical Relevance—Substantial
interobserver variation was detected. Standardization
of pathologic descriptions of intestinal tissue is necessary
for meaningful comparisons with published
articles. Clinicians must be cautious about correlating
clinical signs and histopathologic descriptions of
intestinal biopsy specimens. (J Am Vet Med Assoc