Colibacillosis refers to any localized or systemic infection caused entirely or partly by avian pathogenic Escherichia coli (APEC). Colibacillosis in mammals is most often a primary enteric or urinary tract disease, whereas colibacillosis in poultry is typically a localized or systemic disease occurring secondarily when host defenses have been impaired or overwhelmed by virulent E. coli strains. The purpose of this study was to investigate the antimicrobial drug resistance pattern of Escherichia coli isolated from broiler chickens farms with colibacillosis infection. Dead birds from commercial broiler chicken farms showing signs of colibacillosis were necropsied and swab samples were collected from internal organs and blood aseptically for the isolation of Escherichia coli. Pure colonies of the bacteria were isolated on solid media and the isolates were identified as E. coli based on morphological and biochemical characteristics. For determination of susceptibility to antibacterial agents, the disc diffusion method on Muller-Hinton agar was used. The following antimicrobial agents were tested: gentamycin, oxytetracyline, colistin, ciprofloxacin, doxycycline, nalidixic acid, co-trimoxazole (trimethoprim-sulfamethoxazole), norefloxacin, lincospectin and cefuroxime. The drug resistance patterns of the organisms were determined as a percentage and reported at three levels: susceptible, intermediate and resistant. All the isolates of Escherichia coli showed resistance to several antibiotics and a pattern of multiple drug resistance was observed. The highest rate of resistance was observed against nalidixic acid (100%) and the least rate of resistance was observed against gentamycin (17%). According to the results of this research care must be taken to avoid secondary infection (colibacillosis) in chicken farms and also avoid in careless antimicrobial consumption in food animals including chickens.

External parasites or ectoparasites, are arthropods that live on or in the skin or feathers, using the host as both shelter and food source. Ectoparasites can have significant impacts on animal health and productivity. The aim of this research was to estimate the prevalence and ectoparasites diversity in pigeons of Zabol, southeast of Iran. A total of 264 pigeons were selected randomly (175 males and 89 females) to evaluate the presence of different ectoparasites. Ectoparasites were collected from different parts of the body and from walls and seams of cubbyholes, using hand lens, forceps, and flashlights to increasing the see sight. The samples were preserved in 70 % alcohol and cleared in lactophenol. The overall prevalence of external parasites in pigeon was 78.40 % [female (33.3 %) and male (66.7 %)]. There was no significant difference of infestation of ectoparasites between male and female (P [ 0.05). Prevalence was higher in adult pigeons (84.11 %) than pipers (54.0 %). Two species of ectoparasites were identified: Argas reflexus and Columbicola columbae.