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Biomedical subjects

P A Wilkins

Publications and source records attributed to P A Wilkins.

At least 19 recordsLinked to original sources
PubMed2007

Retrospective study of dystocia in mares at a referral hospital.

REASONS FOR PERFORMING STUDY: The period between the onset of dystocia and its resolution has an important bearing on fetal outcome. There are few published data on which to base decisions regarding optimum management of cases in practice. OBJECTIVES: To evaluate and compare the effects of a coordinated dystocia management protocol (CDMP) with that of a previous protocol of random management on time to resolution and outcome in both an emergency dystocia referral population of mares (referred emergency cases: EM) and in a population of mares residing in hospital due to high risk pregnancy (HRP) concerns that then experience dystocia at parturition. METHODS: Retrospective study performed at a university hospital referral centre of cases presenting from 1991-2004 divided into Group 1 (pre-CDMP) and Group 2 (CDMP). RESULTS: Medical records of 71 cases with dystocia were retrieved and data recorded. For referred emergency cases (EM), time from hospital presentation to resolution decreased significantly by 32 min (P = 0.03) after institution of CDMP. Survival rate of mares at discharge was 86%. Survival of EM foals was low, with 10% in Group 1 and 13% in Group 2, surviving to discharge. For EM foals delivered alive, survival to discharge was 30% and 43% in Groups 1 and 2, respectively. Median Stage II was significantly (P < 0.001) different at 71 and 282 min for EM foals delivered alive vs. those not alive at delivery, respectively. Median duration of Stage II was also significantly (P < 0.001) different between EM foals surviving and not surviving to discharge, at 44 and 249 min, respectively. Survival of HRP dystocia foals to discharge was 79%. CONCLUSIONS: Although CDMP reduced the time from presentation at the hospital to resolution significantly for EM, total duration of Stage II for EM was unchanged, as was foal outcome. POTENTIAL RELEVANCE: Very early referral of mares with dystocia to referral centres with dystocia management protocols may improve fetal outcome as increased duration of Stage II in the horse affects fetal outcome negatively.

Animals↗
PubMed2004

Congenital cystic polypoid rectal hamartoma in a newborn foal.

A neonatal foal with signs of rectal bleeding was diagnosed with an intraluminal rectal mass and intussusception on surgical exploration of the abdomen. Histologically, the mass consisted of cystic spaces lined by simple columnar epithelium with numerous goblet cells and was surrounded by thin bands of smooth muscle in a myxomatous stroma. Although the mass shared similarities with retrorectal cystic hamartoma (tailgut cyst) and juvenile polyps, described in human medicine, location and histologic findings were not entirely consistent with either condition.

Animals↗
PubMed2001

Extravascular lung water in the exercising horse.

Seven Standardbred horses were exercised on a treadmill at speeds (approximately 12 m/s) producing maximal heart rate, hypoxemia, and a mean pulmonary arterial pressure of approximately 75 mmHg. Extravascular lung water was measured by using transients in temperature and electrical impedance of the blood caused by a bolus injection of cold saline solution. Lung water was approximately 3 ml/kg body wt when standing but did not increase significantly with exertion. We conclude that any increase in fluid extravasation from the pulmonary hypertension accumulates in the lung at a level that is less than that detectable by this method. At maximal exertion, the volume of blood measured between the jugular vein and the carotid artery increased by approximately 8 ml/kg, and the actively circulating component of the systemic blood volume increased by approximately 17 ml/kg with respect to corresponding values obtained when walking before exertion. These volume increases, reflecting recruitment and dilatation of capillaries, increase the area for respiratory gas exchange and offset the reduced transit times that would otherwise be imposed by the approximately eightfold increase in cardiac output at maximal exertion.

Animals↗
PubMed2001

Clinical, pathologic, immunohistochemical, and virologic findings of eastern equine encephalomyelitis in two horses.

Natural eastern equine encephalitis alphavirus (EEEV) infection was diagnosed in two adult horses with anorexia and colic, changes in sensorium, hyperexcitability, and terminal severe depression. Myocardium, tunica muscularis of stomach, intestine, urinary bladder, and spleen capsule had coagulative necrosis and perivascular lymphocytic infiltrate. Central nervous system (CNS) lesions were diffuse polioencephalomyelitis with leptomeningitis characterized by perivascular T lymphocyte cuffing, marked gliosis, neuronophagia, and multifocal microabscesses. Lesions were more prominent within cerebral cortex, thalamus, hypothalamus, and mesencephalon. EEEV was identified in the cytoplasm of cardiac myocytes and smooth muscle cells of spleen, stomach, intestine, urinary bladder, blood vessels, and dendritic cells. In the CNS, EEEV-positive cells included neurons, astrocytes, oligodendrocytes, microglia, and neutrophils. EEEV was isolated from the CNS of both horses. The detailed description of the encephalic and spinal EEEV localization and the findings of EEEV in extraneural tissues contribute to the understanding of this important multisystemic zoonotic disease.

Animals↗
PubMed2000

Listeria monocytogenes septicemia in a Thoroughbred foal.

Listeria monocytogenes septicemia was diagnosed in a 6-day-old Thoroughbred foal. Primary clinical signs included fever, depression, diarrhea, and respiratory distress. Hematologic abnormalities included leukopenia, neutropenia, degenerative left shift, and hyperfibrinogenemia. Clinical chemistry and blood gas abnormalities included metabolic acidosis, hypoxemia, hypocapnia, hypoglycemia, and hyponatremia. Despite aggressive therapeutic intervention and intensive care, the foal died within 12 hours of admission. A postmortem examination was performed, and the primary gross lesion was bilaterally severe, focally extensive bronchopneumonia. Histopathology revealed severe subacute multifocal suppurative bronchopneumonia with necrotizing vasculitis and intralesional coccobacilli. Cultures of blood collected at admission and immediately prior to death were positive for L. monocytogenes, as were cultures obtained from lung and liver at necropsy. Immunohistochemical examination of formalin-fixed tissues revealed abundant intra- and extracellular L. monocytogenes antigen within the lung and intravascularly in multiple organs.

Animals↗
PubMed2000

Fatal nonneurological EHV-1 infection in a yearling filly.

A case of fatal nonneurological equine herpesvirus 1 (EHV-1) infection in a yearling filly is described. Gross lesions included extensive pulmonary edema, prominent laryngeal lymphoid follicles, and congestion and edema of the dorsal third ventricle choroid plexus. Histologically, there was vasculitis, hemorrhage, and edema in the lungs and dorsal third ventricle choroid plexus as well as mild intestinal crypt necrosis with occasional intranuclear inclusion bodies. The perivascular and vascular inflammatory infiltrates were comprised mainly of T lymphocytes and macrophages. EHV-1 antigen was identified within the nucleus and cytoplasm of endothelial cells, dendritic-like cells of the pharyngeal lymphoid follicles, pharyngeal glandular epithelium, crypt enterocytes, and monocytes. Attempted virus isolation was negative. Weak seroconversion for EHV-1 was observed. Herpesvirus-like particles were identified within pharyngeal endothelial cells by transmission electron microscopy. Polymerase chain reaction amplified 369 and 188 base-pair fragments specific for EHV-1. The scarcity of pathognomonic viral inclusions and lesions in this case suggests that this disease may not be recognized, particularly in situations when ancillary laboratory procedures are limited.

Animals↗
PubMed1999

Clinical, haematological and biochemical findings in foals with neonatal Equine herpesvirus-1 infection compared with septic and premature foals.

A retrospective multicentre study comparing historical, clinical, haematological, acid-base and biochemical findings of foals with Equine herpesvirus-1 (EHV-1) infection, septicaemia or prematurity was performed to determine if early diagnosis of EHV-1 foals was possible. Fifty-three foals were studied and were assigned to one of 2 groups: herpes positive (n = 14) or herpes negative (n = 39). The latter group included 20 septic, 11 premature, and 8 premature and septic foals. The presence of herpes antigen was confirmed by immunoperoxidase histochemical staining of tissues from necropsied foals. A nonparametric statistical analysis followed by a backwards elimination logistic regression was performed to establish a model at a P value of <0.05. All herpes positive foals died, while 47% (9/19) of the septic foals survived. Based upon our analysis, herpes positive foals were more likely to have total white blood cell counts less than 3 x 10(9)/l and to be icteric as compared to the septic and premature foals. Despite profound hepatic necrosis in the herpes positive foals, liver enzymes were not elevated and were not significantly different from the controls.

Acid-Base Equilibrium↗
PubMed1997

Equine viral arteritis in newborn foals: clinical, pathological, serological, microbiological and immunohistochemical observations.

Clinical, pathological, immunohistochemical, serological and microbiological findings are described for 2 geographically and temporally distinct equine arteritis virus (EAV) epidemics in newborn foals. Outbreak A occurred at a commercial Standardbred breeding facility; Outbreak B began in a group of research animals. Clinical signs were severe and primarily referable to the respiratory tract. Fever and leucopenia and/or thrombocytopenia were observed in foals surviving for more than 24 h. The most common gross pathological findings were limited to the respiratory tract. Common histopathological findings included interstitial pneumonia, lymphocytic arteritis and periarteritis with fibrinoid necrosis of the tunica media. Renal tubular necrosis was noted in 2 foals. Immunoperoxidase histochemistry combined with virus isolation was diagnostic in all cases.

Animals↗
PubMed1994

Measurements of blood flow and xanthine oxidase activity during postischemic reperfusion of the large colon of ponies.

To assess right colic artery blood flow and relevance of xanthine dehydrogenase/xanthine oxidase after experimentally induced strangulation obstruction and reperfusion of the colon, 5 ponies were subjected to 2.5 hours of complete ischemia of the left dorsal and ventral colons, allowed to recover from surgery, and monitored during a 48-hour reperfusion period. Five ponies were subjected to sham surgery and served as controls. All ponies had a Doppler ultrasound blood flow monitor implanted on the right colic artery near the pelvic flexure 10 to 14 days prior to the ischemic period. Colic artery blood flow was monitored prior to, during, and for 4 hours after surgery. Blood samples from the right colic artery and vein distal to the obstruction site were collected during surgery (prior to ischemia, after 1 and 2 hours of ischemia, and after 10 and 60 minutes of reperfusion) for determination of arterial and venous blood gas tensions and electrolytes. Prior to surgery, blood selenium and plasma vitamin E (alpha-tocopherol) concentrations and blood glutathione peroxidase (GPX) activity were determined to assess the status of endogenous antioxidants. Combined xanthine dehydrogenase (XDH) plus xanthine oxidase (XO) activity, and XO activity alone (nanomoles per minute per gram of tissue) were determined, using a dual-spectrophotometric technique. Xanthine dehydrogenase and oxidase activities were determined prior to ischemia, after 1 and 2 hours of ischemia, and at 1 and 48 hours after reperfusion. Median blood flow in the experimental and control groups (156 ml/min and 110 ml/min, respectively) was not statistically different before surgery, and was significantly (P < 0.02) lower in the experimental (4 ml/min) vs the control group (72.5 ml/min) during the ischemic period. Experimental ponies had significantly (P < 0.03) lower right colic artery blood flow during the 4 hours immediately after recovery from anesthesia. Significant difference was not observed in right colonic venous bicarbonate concentration between groups at any time. Median right colonic venous PCO2, pH, and standard base excess were different (P < 0.001) between groups during the ischemic period only. Median venous oxygen saturation and median venous PO2 were significantly (P < 0.001) lower in the experimental ponies at the end of 2 hours of ischemia, but were significantly (P < 0.05) increased during the reperfusion phase. Median venous potassium concentration was significantly (P < 0.01) higher in experimental ponies during the ischemic and reperfusion phases. Vitamin E and GPX values were within normal limits for all ponies.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1994

A herd outbreak of equine leukoencephalomalacia.

Equine leukoencephalomalacia (ELEM) affected 6 of 10 pleasure horses in adjacent paddocks at a boarding facility. Four of the 6 affected horses died or were euthanized. Two of 3 horses presented for treatment survived with complete resolution of clinical signs. Treatment was primarily supportive. Dimethyl sulfoxide, dexamethasone, flunixin meglumine and thiamine were administered as anti-inflammatory agents and to decrease or prevent cerebral edema. Fusarium monileforme was cultured from ear corn fed the affected horses. Fumonisin B1, B2 and B3 were isolated.

Animal Feed↗
PubMed1994

Efficacy of intravenous plasma to transfer passive immunity in clinically healthy and clinically ill equine neonates with failure of passive transfer.

The efficacy intravenous plasma to transfer passive immunity to clinically healthy colostrum-deprived and clinically ill foals with failure of passive transfer was investigated. Efficacy of transfer was evaluated by the elevation of serum IgG per gram of IgG administered as a function of body weight. Colostrum deprived healthy foals had a significantly greater increase in serum IgG than did clinically ill foals with failure of passive transfer. Knowledge of the IgG content of plasma to be administered and the health status of a foal with failure of passive transfer should allow more accurate prediction of an individual foal's response to treatment.

Animals↗
PubMed1993

Technique for long-term right dorsal colon fistulization in ponies.

Right dorsal colon fistulas, 2.5 cm in diameter, were created in 2 healthy ponies, using a 2-stage surgical procedure. The first stage consisted of resection of portions of the 16th and 17th ribs on the right side, followed by surgical creation of a 6- to 8-cm-diameter adhesion between the right dorsal colon and the body wall. Fistulas were created approximately 2 weeks after the first surgery by sharp dissection through the adhesion into the lumen of the colon. The fistulas have been satisfactorily maintained for > 2 years by de Pezzer catheters (45 F). Ponies with fistulas have been used for gastrointestinal experiments.

Animals↗
PubMed1991

Xanthine oxidase formation during experimental ischemia of the equine small intestine.

We hypothesized that xanthine oxidase plays a role in the postischemic reperfusion injury in the equine small intestine. Under anesthesia, four horses and two ponies underwent ischemic strangulating obstructions of segments of the proximal jejunum, mid-jejunum and ileum. Prior to vascular occlusion, and at 1 h and 2 h of ischemia, full-thickness intestinal biopsies were collected for histopathological evaluation and for determination of combined xanthine dehydrogenase (XDH) plus xanthine oxidase (XO) activity, and XO activity alone. The level of XO activity was expressed in percentage according to the ratio of XO/(XDH + XO). We found a nearly threefold increase in the combined level of XDH plus XO activity from ileum to duodenum (p less than 0.04). However, the preischemic level of % XO activity did not vary significantly (p = 0.61) between segments of jejuno-ileum. Likewise, no significant difference was noted between intestinal segments after ischemia. Therefore, the data from all intestinal segments were pooled for each time and analyzed using Wilcoxon's signed rank test (one-tailed). Compared to the pre-ischemic level of % XO activity (median 27%), the % XO activity increased after 1 h of ischemia (median 37.0%), reaching statistical significance (p = 0.016). There were no statistical differences between the preischemic % XO activity and the % XO activity in non-ischemic bowel at the end of the anesthetic period. During ischemia, % XO activity increased, which lends credence to the importance of xanthine oxidase in previously-documented reperfusion injury in the equine small intestine.

Animals↗