COMPOSITION OF THE BACTERIAL-FLORA OF THE EQUINE CECUM AND POSSIBLE IMPLICATIONS FOR THE PATHOGENESIS OF TYPHLOCOLITIS

Typhlocolitis is a severe problem in equine practice. It is often a se quel to surgically treated diseases of the gut that in the horse go al ong with colic symptoms. Such intestinal diseases as well as typhlocol itis itself are supposedly caused or followed by a disruption of the n ormal intestinal microflora. This study tries to characterise the alte rations concerning the bacterial composition in the caecal contents of 10 horses exhibiting colic symptoms and 5 horses with typhlocolitis a s compared to the findings in 6 healthy horses. Horses with colic symp toms or typhlocolitis showed a 10 to 100-fold rise in aerobically cult ured bacteria, especially in Enterbactericeae, compared to healthy ani mals. Colony counts for gramnegative anaerobes in horses with colic we re remarkably low (lg 4,6(+/-2,0/g) compared to horses with typhlocoli tis (lg 6,9 (+/-1,9/g). The most prominent finding in comparison to he althy horses, however, was the frequency with that clostridia were iso lated in high numbers from sick horses especially from animals with ty phlocolitis. Colony counts for clostridia reached more than lg 6/9 int estinal contents in 5 horses with colic and in all horse with typhloco litis while from the 10 healthy horses only Clostridium (Cl.) perfring ens could be cultured once in low numbers of less than lg 1/g. Isolati on rates and species variations for clostridia were highest in patient s with typhlocolitis. Considering the nature of the lesions seen in ty phlocolitis the potentially pathogenic species Cl. perfringens and Cl. difficile are most notable among the isolated clostridia. Cl, perfing ens was regularly cultured from horses with typhlocolitis and with the exception of one animal was detectable in high numbers of approximate ly lg 6/g. Cl. difficle was isolated from three horses with typhlocoli tis. Colony counts for this clostridial species were once as high as l g 6/g and two times below lg 1/g. All three isolates produced cytotoxi n in vitro, while in the caecal contents toxin was only detectable in the horse with high colony counts. In this animal with necrotising typ hlitis and erosive colitis high numbers of Cl. difficile and Cl, perfr ingens were cultured at the same time with more than lg 7 colony formi ng units of Salmonella Typhimurium var. Copenhagen/g caecal contents.