Morphological and functional aspects of oxytetracycline administration to conventional rats

Abstract

1. Studies were performed with female rats to examine the effect of various levels of orally administered oxytetracycline on body-weight, weight of various portions of the intestinal tract, weight of mesenteric lymph nodes, distribution pattern of the tissue elements in the terminal portion of the ileum, and on the susceptibility to invasion bySalmonella typhi-murium.2. There was no growth promotion resulting from any antibiotic treatment. A consistent finding was the decrease in the wet weight of mesenteric lymph nodes in the rats given antibiotic.3. In the bacteriological test, no differences between antibiotic-fed and control groups were observed in isolations from the liver, spleen or intestinal tissue. It was concluded that there were no effects of oxytetracycline administration on invasive capacity of orally administeredS. typhi-murium.

Effects of dietary levels of oxytetracycline on the growth and organ weights of guinea fowl (Numida meleagris)

“…Vo et al (1985) also recorded a growth promoting effect of oxytetracycline on guinea fowl keets at the only inclusion level (50 mg/kg) they examined. Antibiotic use may be described (Ruitenberg et al 1973) as growth promoting (< 20 mg/kg diet), prophylactic (20-100 mg/kg diet) or therapeutic (over 100 mg/kg diet). By this definition, therefore, the 50 mg/kg diet used by Vo et al (1985) is prophylactic.…”

“…This might be due to quantitative or qualitative changes in the microflora of the intestine. Ruitenberg et al (1973) have speculated that such changes could lead to alterations not only in the intestines but in other visceral organs. In the present study a signficant reduction in intestinal wet weight occurred only at the oxytetracycline level of 20 mg/kg diet.…”