: Pasteurella multocida; infection; ostrich.Pasteurella multocida is a significant cause of fowlcholera and affects both domestic and wild avianspecies (Rimler & Glisson, 1997) resulting in severeeconomic losses among poultry populations(Samuel et al., 1997; Dunbar et al., 2000). Outbreaksof fowl cholera are often associated with intensivepoultry production, climatic stress, and possiblepredation in free range. The severity of infection isusually controlled by strict sanitation and biosecuritymeasures as well as by vaccination (Rimler & Glisson,1997).The diagnosis of P. multocida is usually made bybacteriological and serological tests (Rimler, 1992).Most of the bacteriological tests rely on microbialisolation and biochemical characterization (Snipeset al., 1990; Fegan et al., 1995). Although microbialisolation is the ‘gold standard’ in the identificationof a new isolate, the morphologic features ofP. multocida are not characteristic enough to differ-entiate it from other gram-negative coccobacilli.Therefore, some key biochemical features, includingpositive indole reaction and ornithine decarboxylase(ODC) activity, are used in the identification ofPasteurellae (Rimler & Glisson, 1997). The applica-tion of key biochemical reactions coupled with theisolation methods had successfully identified out-breaks of fowl cholera in turkeys (Blackall et al.,1995). Despite the worldwide distribution ofP. multocida infections in domestic and wild birds,reports of pasteurellosis in ostriches are rare. To ourknowledge, there is only one report of an outbreakin Kano Zoo, Nigeria (Okoh, 1980).In this communication, efforts were made todiagnose septicaemic pasteurellosis in three-to-ninemonth old ostriches that died suddenly of fulminantrespiratory distresses. Out of a total of 486 birdsraised in a commercial breeding farm in centralSaudi Arabia, 180 were affected and 75 died. Earlysigns included inappetence, runny nose, salivation,neck dropping, and shivering. The prodromes ofthese signs continued for one-to-two days followedby complete anorexia, wing dropping, shivering,and recumbency with obvious respiratory distress.Autopsies were performed on the 75 birds that died.At post mortem, the observed lesions were conjunctivaland pharyngeal oedema (100%; Figs 1 and 2), hae-morrhagic tracheitis (100%; Fig. 3), haemorrhageson the heart (100%; Fig. 4), stomach (90%), intes-tines (85%), and kidneys (75%), and congestion ofthe spleen (95%), pancreas (85%), and liver (80%).The lungs of most autopsied birds were normal andno typical pneumonic lesions were detected exceptfor minor congestion (20%).At autopsy, lesion swab specimens were collectedaseptically from deep tissues after the surface hadbeen burnt following standard microbiologicaltechniques (Miller, 1996). All specimens were cul-tured on 5% sheep blood agar and eosin methyleneblue agar (Difco Laboratories) and incubated at