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  • Author or Editor: Anthony Blikslager x
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Abstract

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 [2], prepuce [3], and penis [3]) 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.

Full access
in American Journal of Veterinary Research
in Journal of the American Veterinary Medical Association

Abstract

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).

Design—Retrospective study.

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 analysis.

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)

Full access
in Journal of the American Veterinary Medical Association
in Journal of the American Veterinary Medical Association

Abstract

Objective—To identify factors associated with development of small colon impaction in horses and with selection of medical versus surgical treatment and to determine the prognosis for affected horses following medical or surgical management.

Design—Retrospective case series.

Animals—44 horses with primary impaction of the small colon.

Procedures—Medical records were reviewed for signalment, history, clinical findings, treatment (medical vs surgical), hospitalization time, and outcome. For comparison purposes, the same information was collected for 83 horses with primary impaction of the large colon.

Results—Diarrhea was the only factor found to be associated with development of small colon impaction. Horses with small colon impaction were 10.8 times as likely to have diarrhea at the time of initial examination as were horses with large colon impaction. Abdominal distension was the only factor associated with use of surgical versus medical treatment. Horses with small colon impaction that were treated surgically were 5.2 times as likely to have had abdominal distension at the time of admission as were horses with small colon impaction that were treated medically. Overall, 21 of 23 (91%) horses treated medically and 20 of 21 (95%) horses treated surgically survived to discharge.

Conclusions and Clinical Relevance—Results suggest that diarrhea may be a risk factor for development of small colon impaction and that horses with small colon impaction that have abdominal distension at the time of initial examination are more likely to require surgical than medical treatment.

Full access
in Journal of the American Veterinary Medical Association

Abstract

Objective—To examine the effects of flunixin meglumine and etodolac treatment on recovery of ischemicinjured equine jejunal mucosa after 18 hours of reperfusion.

Animals—24 horses.

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 were determined.

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 2004;65:761–769)

Full access
in American Journal of Veterinary Research

Abstract

Objective—To determine whether treatment of horses with firocoxib affects recovery of ischemic-injured jejunum, while providing effective analgesia.

Animals—18 horses.

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.

Full access
in American Journal of Veterinary Research

Abstract

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.

Full access
in American Journal of Veterinary Research
in Journal of the American Veterinary Medical Association

Abstract

OBJECTIVE

To describe a case of tracheal injury secondary to gunshot trauma in a rhinoceros.

ANIMALS

5-year-old female white rhinoceros (Ceratotherium simum).

CLINICAL PRESENTATION, PROGRESSION, AND PROCEDURES

The rhinoceros was found alive with an apparent bullet entry wound cranial to the left shoulder. The rhinoceros was agitated and had bilateral epistaxis and increased respiratory noise. Immobilization of the animal facilitated closer examination and initiation of medical therapy. Radiographs obtained of the neck region at this first examination were nondiagnostic. Subsequent immobilization events allowed for further diagnostics and treatment.

TREATMENT AND OUTCOME

Initial treatment included a broad-spectrum antibiotic and a corticosteroid. Five days following the injury, the rhinoceros was considered stable, and the animal was immobilized to investigate the cause of the epistaxis and respiratory signs. Tracheoscopy revealed a full-thickness penetrating wound in the mid to caudal region of the trachea, and the surface of a metallic projectile was viewed within the wound. Medical treatment was continued and the rhinoceros was managed conservatively. At 14 days, radiographs of the neck made with a more powerful unit revealed tissue emphysema dorsal to the trachea. A subsequent tracheoscopy 54 days after injury revealed a granulated wound. Follow-up at 4 years after injury determined that the rhinoceros was reported to be behaving normally and had successfully calved.

CLINICAL RELEVANCE

Gunshot wounds associated with poaching are a prevalent problem in rhinoceros in Africa. Although more aggressive therapy including surgery may likely be considered in zoo or domestic animals, limited conservative treatment was successful in this wild-managed rhinoceros.

Full access
in Journal of the American Veterinary Medical Association