Objective—To determine whether ischemia and flunixin
affect in vitro lipopolysaccharide (LPS) absorption
in samples of the jejunum of horses.
Procedure—Horses were anesthetized, a midline
celiotomy was performed, and the jejunum was located.
Two 30-cm sections of jejunum (60 cm apart)
were selected. One segment was designated as control
tissue; ischemia was induced in the other segment
for 120 minutes. Horses were then euthanatized.
Mucosa from each jejunal segment was mounted
on Ussing chambers and treated with or without
flunixin. Tissues from 6 horses were used to assess
permeability to radiolabeled LPS; mucosal samples
from the remaining 6 horses were incubated with
fluorescent-labeled LPS (FITC-LPS) and examined histologically.
Production of tumor necrosis factor-α (TNF-α) and production of LPS-binding protein (LBP) were
assessed as indicators of mucosal response to LPS.
Results—Ischemia significantly increased mucosal
permeability to LPS, but by 180 minutes, the mucosa
was not more permeable than control tissue. Flunixin
treatment adversely affected intestinal barrier function
throughout the experiment but did not result in
increased mucosal permeability to LPS. Compared
with control tissues, LBP production was increased
by ischemia and reduced by exposure to LPS. In
ischemic tissue, FITC-LPS entered the lamina propria
but TNF-α was produced on the mucosal side only,
indicating little response to the absorbed LPS.
Conclusions and Clinical Relevance—Ischemia
increased LPS passage across equine jejunal mucosa.
Flunixin delayed mucosal recovery but did not exacerbate
LPS absorption. Evaluation of the clinical importance
of flunixin-associated delayed mucosal recovery
requires further in vivo investigation. (Am J Vet Res
Objective—To examine whether a zinc l-carnosine compound used for treatment of suspected gastric ulcers in dogs ameliorates acid-induced injury in canine gastric mucosa.
Sample—Gastric mucosa from 6 healthy dogs.
Procedures—Mucosa from the gastric antrum was harvested from 6 unadoptable shelter dogs immediately after euthanasia and mounted on Ussing chambers. The tissues were equilibrated for 30 minutes in neutral Ringer's solution prior to incubation with acidic Ringer's solution (HCl plus Ringer's solution [final pH, 1.5 to 2.5]), acidic Ringer's solution plus zinc l-carnosine compound, or zinc l-carnosine compound alone. Tissues were maintained for 180 minutes in Ussing chambers, during which permeability was assessed by measurement of transepithelial electrical resistance. After the 180-minute treatment period, tissues were removed from Ussing chambers and labeled with immunofluorescent anti–active caspase-3 antibody as an indicator of apoptosis.
Results—Permeability of the gastric mucosa was significantly increased in a time-dependent manner by addition of HCl, whereas control tissues maintained viability for the study period. Change in permeability was detected within the first 15 minutes after acid application and progressed over the subsequent 150 minutes. The zinc l-carnosine compound had no significant effect on this increase in permeability. Apoptosis was evident in acid-treated tissues but not in control tissues. The zinc l-carnosine compound did not protect against development of apoptosis.
Conclusions and Clinical Relevance—Addition of HCl caused a dose-dependent increase in gastric permeability over time and apparent induction of apoptosis as determined on the basis of immunofluorescence. However, there was no significant protective effect of a zinc l-carnosine compound. Nonetheless, results suggested the utility of this method for further studies of canine gastric injury.
Objective—To assess expression of cyclooxygenase (COX)-1 and -2 in naturally occurring squamous cell carcinomas (SCCs) and the analogous normal tissues in horses.
Sample Population—Tissue samples collected from 3 conjunctival, 2 vulvar, 4 preputial, and 5 penile SCCs during surgical excision in 14 horses and from corresponding body regions (conjunctiva [n = 5 horses], vulva , prepuce , and penis ) in 5 horses euthanized for reasons unrelated to neoplasia.
Procedures—Tissue samples were snap frozen in liquid nitrogen and stored at −80°C until analysis. Protein was extracted from the frozen tissues, and western blot analyses were performed. Nonneoplastic and abnormal tissues from each body region were run on the same blot, and blots were run in triplicate. Molecular-weight markers and COX-1 and 2 ovine standards (positive control samples) were run concurrently on the gels; negative control samples were not used.
Results—All tissues, including the nonneoplastic and SCC tissues, expressed both COX-1 and -2 proteins.
Conclusions and Clinical Relevance—Results indicated that the expression of COX proteins in both nonneoplastic and SCC-affected tissues in horses is markedly different from that in other species. The reason for the potential benefit of COX-2 inhibitors in horses and other species is unknown. Further research needs to be performed to evaluate the efficacy of COX-2 inhibitors as cancer treatments in horses. Investigation of the mechanisms of tumor development in horses should be performed to increase understanding of this disease and ascertain how the mechanisms differ from those in other animals.
Objective—To determine prevalence and risk factors
for development of ileus of the large intestine after
surgery in horses, identified by reduced postoperative
fecal output (RPFO).
Animals—37 horses that developed RPFO after
undergoing general anesthesia for reasons unrelated
to the gastrointestinal tract.
Procedure—Fecal output was obtained from medical
records as number of defecations per 24-hour period
after surgery; RPFO was defined as ≤ 3 defecations
per 24-hour period after surgery. The reference population
included 48 horses that defecated ≥ 4 times
during the same period. Demographic, clinical, and
surgical variables were evaluated for their association
with development of RPFO by use of logistic regression
Results—Ten (12%) horses, all of which had RPFO,
developed signs of colic after surgery. Horses ≥ 5
years old that underwent orthopedic procedures of >
60 minutes’ duration and that did not receive
phenylbutazone after surgery were at significant risk
for developing RPFO.
Conclusions and Clinical Relevance—Results suggest
that after surgery unrelated to the gastrointestinal
tract in horses, there is an intermediate clinical
phase characterized by reduced fecal output preceding
overt signs of colic. Recognition of RPFO may
reduce morbidity and mortality of such horses. (J Am
Vet Med Assoc 2001;218:414–420)
Objective—To determine whether treatment of horses with firocoxib affects recovery of ischemic-injured jejunum, while providing effective analgesia.
Procedures—Horses (n = 6 horses/group) received saline (0.9% NaCl) solution (1 mL/50 kg, IV), flunixin meglumine (1.1 mg/kg, IV, q 12 h), or firocoxib (0.09 mg/kg, IV, q 24 h) before 2 hours of jejunal ischemia. Horses were monitored via pain scores and received butorphanol for analgesia. After 18 hours, ischemic-injured and control mucosa were placed in Ussing chambers for measurement of transepithelial resistance and permeability to lipopolysaccharide. Histomorphometry was used to determine denuded villus surface area. Western blots for cyclooxygenase (COX)-1 and COX-2 were performed. Plasma thromboxane B2 and prostaglandin E2 metabolite (PGEM) concentrations were determined.
Results—Pain scores did not significantly increase after surgery in horses receiving flunixin meglumine or firocoxib. Transepithelial resistance of ischemic-injured jejunum from horses treated with flunixin meglumine was significantly lower than in saline- or firocoxib-treated horses. Lipopolysaccharide permeability across ischemic-injured mucosa was significantly increased in horses treated with flunixin meglumine. Treatment did not affect epithelial restitution. Cyclooxygenase-1 was constitutively expressed and COX-2 was upregulated after 2 hours of ischemia. Thromboxane B2 concentration decreased with flunixin meglumine treatment but increased with firocoxib or saline treatment. Flunixin meglumine and firocoxib prevented an increase in PGEM concentration after surgery.
Conclusions and Clinical Relevance—Flunixin meglumine retarded mucosal recovery in ischemic-injured jejunum, whereas firocoxib did not. Flunixin meglumine and firocoxib were effective visceral analgesics. Firocoxib may be advantageous in horses recovering from ischemic intestinal injury.
Objective—To examine the effects of flunixin meglumine
and etodolac treatment on recovery of ischemicinjured
equine jejunal mucosa after 18 hours of reperfusion.
Procedure—Jejunum was exposed to 2 hours of
ischemia during anesthesia. Horses received saline
(0.9% NaCl) solution (12 mL, IV, q 12 h), flunixin meglumine
(1.1 mg/kg, IV, q 12 h), or etodolac (23 mg/kg, IV,
q 12 h). Tissue specimens were obtained from
ischemic-injured and nonischemic jejunum immediately
after ischemia and 18 hours after recovery from
ischemia. Transepithelial electric resistance (TER) and
transepithelial flux of tritium-labeled mannitol measured
mucosal permeability. Denuded villous surface
area and mean epithelial neutrophil count per mm2
were calculated. Western blot analysis for cyclooxygenase
(COX)-1 and -2 was performed. Pharmacokinetics
of flunixin and etodolac and eicosanoid concentrations
Results—Ischemic-injured tissue from horses treated
with flunixin and etodolac had significantly lower TER
and increased permeability to mannitol, compared with
that from horses treated with saline solution. Epithelial
denudation after ischemia and 18 hours after recovery
was not significantly different among treatments. Both
COX-1 and -2 were expressed in ischemic-injured and
nonischemic tissues. Ischemia caused significant
upregulation of both COX isoforms. Eicosanoid concentrations
were significantly lower in tissues from flunixin
and etodolac-treated horses, compared with that
from horses treated with saline solution.
Conclusions and Clinical Relevance—Flunixin and
etodolac treatment retarded recovery of intestinal
barrier function in jejunal mucosa after 18 hours of
reperfusion, whereas tissues from horses treated
with saline solution recovered baseline values of TER
and permeability to mannitol. (Am J Vet Res
OBJECTIVE To characterize epithelial cells of the small intestine and colon in horses without clinical gastrointestinal abnormalities with an emphasis on the stem cell niche constituents.
SAMPLE Mucosal biopsy specimens from small and large intestines obtained from 12 horses euthanized for reasons unrelated to gastrointestinal disease or systemic disease.
PROCEDURES Intestinal biopsy specimens were collected by sharp dissection immediately following euthanasia. Specimens were prepared for immunohistochemical, immunofluorescence, and transmission electron microscopic imaging to detect and characterize each epithelial cell type. Antibodies against protein biomarkers for cellular identification were selected on the basis of expression in other mammalian species.
RESULTS Intestinal epithelial cell types were identified by means of immunostaining and morphological characterization with transmission electron microscopy. Some differences in biomarker expression and antibody cross-reactivity were identified in equine tissue, compared with other species. However, each known type of mucosal epithelial cell was identified in equine tissue.
CONCLUSIONS AND CLINICAL RELEVANCE The methodology used can enhance detection of stem cells and progenitor cells as well as postmitotic cell lineages in equine intestinal tissues. Results may have relevance to regenerative potential of intestinal mucosa and survival in horses with colic.