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Biomedical subjects

E M Milne

Publications and source records attributed to E M Milne.

At least 19 recordsLinked to original sources

Observations on the interstitial cells of Cajal and neurons in a recovered case of equine dysautonomia (grass sickness).

This paper describes the histopathological and immunohistochemical changes in the central, autonomic and enteric nervous systems in a well-documented case of equine dysautonomia (ED), after the animal had recovered without significant residual clinical signs. Evidence of neuronal degeneration, such as neuronal chromatolysis, glial scars or a decrease in density of neurons, was not observed in the midbrain, pons, medulla oblongata or spinal cord, including the nuclei of cranial nerves III, V, VII, X and XII. In addition, no evidence of muscle denervation or re-innervation, such as group atrophy of clusters of cells or grouping of cells of similar size in the triceps muscle, was observed. These findings support the hypothesis that the chromatolytic motor neurons may not progress to cell death in ED. The autonomic ganglia showed evidence of previous neuronal loss. In the myenteric and submucosal plexuses of the ileum there was significant loss of enteric neurons. However, in the ileum, a continuous network of interstitial cells of Cajal (ICC) was observed by means of immunohistochemical techniques. It is possible that recovery without significant residual clinical signs was associated with lack of damage to, or more likely recovery of, the ICC, which have a pacemaker function in the intestinal tract.

Animals↗

Evaluation of urinalysis as an aid in the diagnosis of equine grass sickness.

To determine whether urinalysis can aid the diagnosis of equine grass sickness, samples of urine from 15 horses with acute grass sickness, eight horses with subacute grass sickness, 17 co-grazing horses and 17 stabled control horses were analysed. The samples from all of the horses with grass sickness had a significantly higher specific gravity, higher protein and creatinine concentrations and a significantly lower pH; the samples from the horses with acute grass sickness also had significantly higher glucose concentrations. These differences may support a diagnosis of grass sickness but they are not pathognomonic for the disease.

Acid-Base Equilibrium↗

Liver and biliary system pathology in equine dysautonomia (grass sickness).

Hepatocellular and hepatobiliary damage was assessed in equine acute, subacute and chronic grass sickness cases (AGS, SAGS, CGS). Histopathological analysis showed that even in some early AGS cases enlarged hepatocytes, hepatocyte vacuolation indicative of lipid accumulation (steatosis), intrahepatocyte, canalicular and periportal deposition of pigments, frequent leucocyte infiltration and cholangitis occurred. Analysis of serum indicated significantly increased levels of unconjugated bilirubin in all groups and conjugated bilirubin in AGS and SAGS groups, increased levels of bile acids in some individuals from each group and significantly increased levels of glutamate dehydrogenase (GLDH) in AGS and SAGS cases. Conjugated bilirubin was significantly elevated in urine of AGS and SAGS cases. The evidence suggests that abnormal liver function involving moderate hepatocellular pathology in conjunction with steatosis and cholestasis may contribute to the pathogenesis of GS.

Acute Disease↗

Heparin, platelet aggregation, neutrophils, and cardiopulmonary bypass.

UNLABELLED: Cardiopulmonary bypass (CPB) is associated with both neutrophil activation and failure of platelets to form large stable aggregates. We aimed to determine the effects of heparin and of neutrophil activation on platelet aggregation in whole blood. Fourteen patients undergoing routine aortocoronary bypass grafting and NSAID-free for over 7 days were studied before and after heparinisation, and at end-CPB. Whole blood, anticoagulated with rHirudin, was stirred for 3 minutes, and macroaggregation in response to collagen (0.6 microg. mL(-1)) or the neutrophil stimulant fMLP (10(-7)M) was determined by whole blood impedance aggregometry. Microaggregation was measured by counting unaggregated single platelets (corrected for haemodilution). The blood of volunteers was studied in vitro. PATIENTS: Before CPB, heparin effectively abolished platelet macroaggregation induced by collagen (20.5 to 1.4 Ohms) or fMLP (3.9 to 0 Ohms (p<0.0001). CPB had no additional effect. Heparinisation also reduced the platelet count from 127 (110-170) to 95 (64-117). The inhibition of macroaggregation could not be reversed by ex vivo heparinase. VOLUNTEERS: In vitro, the same heparin concentration, as measured in vivo (4 micromL(-1)), inhibited collagen-induced macroaggregation (20.3 to 14.7 Omega), but this effect was less than that observed ex vivo and was reversed by heparinase. In vitro heparin promoted fMLP macroaggregation (2.9 to 8.6 Omega). The inhibition of macroaggregation resulted from heparinisation, per se, rather than CPB and was insensitive to heparinase. There was less inhibition by in vitro heparin, which was reversible by heparinase, indicating a direct effect of heparin in vitro. The disparate findings are suggestive of an indirect action by heparin in vivo on macroaggregation, although heparin had a small direct stimulatory action on microaggregation.

Anticoagulants↗

Clinicopathological features of equine primary hepatic disease: a review of 50 cases.

The clinicopathological features of 50 cases of equine hepatic disease were reviewed. There was a wide range of clinical signs and at least 50 per cent of the animals exhibited either dull demeanour, anorexia, abdominal pain, cerebral dysfunction and/or weight loss. Life-threatening complications of hepatic failure recorded were: gastric impaction in 10 cases, bilateral laryngeal paralysis in seven cases and coagulopathy in five cases. All the cases had high activities of gamma-glutamyl transferase (GGT) and most had high activities of glutamate dehydrogenase (GLDH) and high concentrations of bile acids. Fewer of the horses had abnormal concentrations of bilirubin, albumin and globulin. The horses that were euthanased or died had significantly higher concentrations of GGT, GLDH and bile acids than the survivors. There were biochemical data for 18 cases with signs of hepatic encephalopathy, all of them had plasma ammonia levels greater than 90 micromol/litre but this was not significantly correlated with the clinical severity of the condition. Half of the cases with hepatic encephalopathy were hyperglycaemic, none was hypoglycaemic, and none had abnormally low levels of plasma urea.

Abdominal Pain↗

Long-term prospects for horses with grass sickness (dysautonomia).

Responses to questionnaires were received from 31 owners of horses or ponies treated for chronic grass sickness (dysautonomia). Contrary to previous opinions the respondents indicated that the majority of the animals were capable of strenuous work, had regained the weight they had lost and, apart from a few residual problems such as difficulty in coping with dry fibrous food, had returned to a normal life. They had recovered slowly and had involved the owners in considerable extra work, but all the owners indicated that they considered the effort to have been worthwhile.

Animals↗

A case-control study of grass sickness (equine dysautonomia) in the United Kingdom.

A case-control study was performed to investigate the epidemiology of grass sickness in the United Kingdom from 1992 to 1995. Data were collected by means of postal questionnaire when cases of grass sickness were identified. Sets of three questionnaires were posted to owners of, or veterinary surgeons attending, cases of grass sickness, with a request to provide information on the case, on one healthy animal on the same premises as the case and on another healthy animal on other premises. Controls were matched to cases by date of onset. After univariate analyses, the probability of grass sickness in horses was modelled using conditional logistic regression techniques. Young animals were found to be at increased rick of grass sickness and females were less likely to become affected, as were animals that had a history of contact with previous cases of the disease. The probability of grass sickness was higher in animals that were on premises where grass sickness had previously occurred, particularly if this was recent. Animals were at particular risk of disease if they changed fields within the previous 2 weeks; the risk thereafter reduced with time. The disease had a seasonal pattern, with a peak from April to June. More than 95% of cases had access to grazing, and 66% occurred after 2 week periods of predominantly dry weather.

Animals↗

An evaluation of the use of cisapride in horses with chronic grass sickness (equine dysautonomia)

A clinical trial was carried out to determine the effect of cisapride on rate of passage of digesta and clinical parameters in horses with chronic grass sickness. Sixteen horses were given intramuscular cisapride (0.1 mg kg-1 three times daily) (group I), and 15 received oral cisapride (0.8 mg kg-1 three times daily) (group O). A liquid-phase marker (cobalt-EDTA) and a solid-phase marker (polystyrene pellets) were given by stomach tube at the beginning of each of three consecutive 7 day periods, i.e., before, during and after cisapride therapy. Seven horses in each group completed the rate of passage trial; the remainder provided clinical data only. The rate of passage was found to be significantly faster after cisapride therapy than before. Comparison with data from 20 normal animals showed a trend towards normal rates of passage after therapy. In cases that died during the trial, the caecum and large colon were the main sites of pellet retention. Dry matter intake was significantly higher after therapy than before in group O and dry matter output was higher after treatment than before in both groups. Gut auscultation score increased in both groups in the periods during and after cisapride administration but heart rate was unaffected. Diarrhoea and colic occurred in each group but its occurrence was not associated with cisapride therapy. The results suggest that by increasing gut motility, cisapride is of benefit in the management of selected cases of chronic grass sickness.

Animals↗

Recovery of horses from dysautonomia (grass sickness).

The outcome for 35 horses with chronic dysautonomia which were kept in the hospital at the Royal (Dick) School of Veterinary Studies and subsequently returned to their owners is recorded. They constituted 42.7 per cent of the 82 chronic cases seen between 1991 and 1994; the other 47 horses were euthanased while in hospital. Of the 35 animals returned to their owners four died and 27 were available for follow up; of these 27, 12 were working competitively and six were being trained for future competitive work. It takes at least a year before it is clear whether a horse can compete successfully again but all the surviving animals were capable of being ridden. Some of the horses suffered excessive sweating, had difficulty in swallowing some foodstuffs, or had coat changes for long periods after returning to a normal weight.

Animals↗

The equine enteric nervous system--neuron characterization and distribution in adults and juveniles.

A study of myenteric and submucosal plexuses was undertaken in the jejunum and ileum of horses and ponies in which no clinical or pathological evidence of intestinal abnormality was apparent. Complete transverse sections of the intestine, stained by a modified haematoxylin and eosin method, were examined using up to 20 sequential sections per animal. Information was gathered from adult, juvenile and fetal equidae. In adults, the longitudinal muscle layers were thinner than the circular muscle layers and the ileum had thicker layers compared to the jejunum. In adults, the submucosal plexus had more neurons per section than the myenteric plexus by mean ratios of 1:3 in the jejunum and 1:1.9 in the ileum. In juveniles, the ratios were respectively 1:1.8 and 1:1.5 and in the fetus 1:2.5 and 1:1.3. The three-dimensional distribution of neurons in both plexuses varied from animal to animal and no consistent pattern was observed. Groups of neurons contained between one and 42 cells per section examined and their length in a cranio-caudal direction varied from 10 to over 100 microns. There were few statistical differences observed between the cranial, middle and caudal portions of either the jejunum or the ileum when neuron groups or neuron numbers per section were examined in 10 adult animals.

Aging↗