Summary The histology from rectal biopsy specimens taken 1980–1990 on 131 occasions from 116 horses, age 1–18 years, with clinical signs of intestinal disease was evaluated and classified retrospectively. In 40 horses, autopsy results were studied for comparison. Biopsy specimens (21 horses) and post mortem rectal tissue (9 horses) from 30 healthy horses, age 4–22 years, were used as controls. In 105 clinical cases, a biopsy was performed on only one occasion, while repeat biopsy was performed in 11 cases. Specimens showed pathological changes in 60 horses. The findings were classified into acute, chronic or chronic active simple proctitis, granulomatous enteritis, eosinophilic granulomatosis/gastroenteritis, eosinophilic‐proctitis, erosive/ulcerative proctitis, pseudomembranous proctitis, proctitis with vasculitis and malignant lymphoma. Mild scattered neutrophil infiltration in the lamina propria was found in controls, but neutrophils in crypt or surface epithelia were abnormal findings. Depletion or hyperplasia of goblet cells sometimes accompanied inflammation. Simple proctitis occurred in association with malignant lymphoma and various inflammatory disorders of the gastrointestinal tract apparent at autopsy. Eosinophilic granulomatosis/gastroenteritis and granulomatous enteritis were diagnosed from biopsy specimens in 6 of 12 and 4 of 9 cases, respectively, of these diseases confirmed at autopsy. Reduction of acid mucins in goblet cells was a prominent feature of eosinophilic granulomatosis. Rectal biopsy was found to be a useful adjunct for evaluation of intestinal disease in the horse.

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Summary The interrelationships between clinical, clinicopathological and morphological findings were studied in 17 cases of equine granulomatous enteritis (GE) and 19 cases of equine eosinophilic granulomatosis (EG) in order to define criteria for clinical diagnosis and to elucidate pathophysiological events in these disorders. Both diseases were marked by progressive wasting and hypoalbuminaemia. They occurred sporadically and showed a predilection for 1‐ to 4 year‐old standardbreds. Excessive protein loss into the gastrointestinal tract was demonstrable by 51Cr‐albumin in both disorders. Serum immunoglobulin levels varied greatly. Significant deviations of mean levels included low IgG(T) in both groups, low IgM in GE and low IgG in EG. D‐xylose absorption was poor in GE, reflecting the villous atrophy of the small bowel in the disease, whereas it was quantitatively unimpaired but tended to be delayed in EG. Diarrhoea was common in EG (14 out of 19 cases) and less frequent in GE (4/17), a difference partly explained by differing major disease sites in the gut (large bowel in EG, small bowel in GE). Marked cholangitis and cholangiohepatitis often occurred in EG, being reflected in some animals by high levels of gammaglutamyltranspeptidase and the appearance of a bile duct isoenzyme of alkaline phosphatase in the serum. Several horses in the EG group showed severe dermatopathy, often including coronitis and loss of chestnuts, whereas severe skin lesions were only occasionally found in the GE series. Anaemia was often present in GE (11/17) but rare in EG (1/19). The study indicated that, although clinical and laboratory findings in EG and GE show much overlap, several features that help to distinguish between the two disorders in the live animal do exist. The results are discussed in the light of possible pathophysiological and pathogenetic mechanisms. Zusammenfassung Klinische und pathophysiologische Merkmale der granulomatösen Enteritis und der eosinophilen Granulomatose beim Pferd Die wechselseitigen Beziehungen zwischen klinischen, klinisch‐pathologischen und morphologischen Befunden wurden in 17 Fällen von equiner granulomatöser Enteritis (GE) und in 19 Fällen von equiner eosinophiler Granulomatose (EG) untersucht, um Kriterien für die klinische Diagnose zu definieren und um die pathophysiologischen Abläufe bei diesen Störungen zu klären. Beide Krankheiten waren gekennzeichnet durch eine progressive Verschlechterung und Hypoalbuminämie. Sie traten sporadisch auf und zeigten eine Prädilektion für ein bis vier Jahre alte Traber. Mit Hilfe von 51Cr‐albumin ließ sich bei beiden Störungen ein exzessiver Proteinverlust in den Gastrointestinaltrakt nachweisen. Die Serumimmunglobulinkonzentrationen variierten erheblich. Signifikante Abweichungen von durchschnittlichen Konzentrationen betrafen in beiden Gruppen die erniedrigten IgG(T), sowie die niedrigen IgM bei der GE und die niedrigen IgG bei der EG. Die schlechte d‐Xylose‐Absorption bei der GE widerspiegelt die Atrophie der Darmzotten im Dünndarm. Bei der EG war di...

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Summary Eight horses (mean weight 438 kg) with chronic obstructive pulmonary disease (COPD) were studied for clinical signs, ventilation/perfusion relationships (V̇A/Q̇) and lung morphology. Four horses were killed and necropsied after the study. In horses with COPD, minute ventilation was almost twice as high as normal, whereas PaO2 was significantly decreased. Cardiac output was normal, but pulmonary artery pressure and pulmonary vascular resistance were significantly increased. The V̇A/Q̇ distribution was abnormal with an increased scatter of V̇A/Q̇ ratios. However, shunt (V̇A/Q̇=0) was increased in one horse only. Ventilation of dead space and high V̇A/Q̇ regions (V̇A/Q̇>10) were increased markedly and comprised 74 per cent of minute ventilation. On lung biopsy, all horses showed chronic bronchiolitis with epithelial hyperplasia and metaplasia. Diffuse acinar hyperinflation also was evident at necropsy. There was a significant inverse correlation between the respiratory rate and the fractional ventilation of normal V̇A/Q̇ regions. Also, there was a significant agreement between the extent of bronchiolar epithelial hyperplasia in necropsy specimens of lungs and the degree of ventilation of high V̇A/Q̇ regions and dead space. The findings suggest that hyperinflation of the lung due to obstructed airways may be the common denominator of increased ventilation of high V̇A/Q̇ regions and dead space ventilation and of elevated pulmonary artery pressure in horses with COPD from chronic bronchiolitis.