BACKGROUND: Infectious and noninfectious causes of lameness result in economic losses in the dairy industry. Digital dermatitis (DD), interdigital necrobacillosis (IDNB) and heel erosion (HE) are considered as the most important infectious causes of lameness. OBJECTIVES: Current study was done in order to evaluate annual incidence of infectious causes of lameness in four different dairy farms in Charmahal & Bakhtiari, Esfahan, Khorasan Razavi and Mazandaran provinces of Iran. METHODS: Records of 71896 hoof trimming and inspections during 2012-2013 on 10100 dairy cows were recorded and analyzed. All information was recorded by professional hoof trimmers and veterinarians during study. RESULTS: Heel erosions (HE) were recorded between 0-13, DD between 0-145 and IDNB between 0-47 cases in each month in different dairy farms that were significantly different. Digital dermatitis (DD) in spring (8.62 percent), IDNB in winter (2.79 percent) and HE in spring (0.68 percent) show the highest seasonal incidence; however, seasonal incidence of infectious causes of lameness were significantly different. Total incidence of 19.18 and 17.45 percent were recorded in 2012 and 2013 that was significantly different for DD. Distribution of infectious lesions were different among different dairy farms as annual incidence of DD was recorded as 32.97 and 30.1 in farm 3 and 0.93 and 0.68 in farm 2 in 2012 and 2013 respectively. CONCLUSIONS: The present survey showed that overall, 20 percent incidence of infectious lesions plays a very important role in financial losses of large dairy farms and needs special attention.

At an abattoir, lesion specimens from 140 condemned sheep livers were collected for bacteriologic culture and for pathologic examination. Grossly, 23 lesions were abscesses; from 9 of which, Fusobacterium necrophorum biovar A (3 in pure culture and 6 in mixed culture) was isolated and from 14 of which, biovar B (6 in pure culture and 8 in mixed culture) was isolated. Escherichia coli was the predominant facultative anaerobic bacterium and Clostridium perfringens was the predominant obligate anaerobic bacterium isolated from the 14 lesions with mixed bacterial infection. Histologically, these lesions had a core of coagulation necrosis, encircled by a zone of necrotic phagocytic cells and bacteria with cellular characteristics of F necrophorum biovars A or B, and a connective tissue capsule. Of the 117 lesions without F necrophorum, 49 were culture-positive (for other organisms) and 69 were culture-negative. These 117 lesions were fibrous and were smaller than the 23 abscesses. A variety of gram-positive and gram-negative facultative anaerobic and obligate anaerobic bacteria was isolated from the culture-positive lesions, but always in low numbers. Eleven culture-negative and 18 culture-positive lesions were examined and had histologic characteristics of parasite-induced granulomas, with numerous eosinophils and epithelioid giant cells. Results of the study indicated that the histologic appearance of ovine hepatic lesions with F necrophorum was similar to bovine liver abscesses caused by F necrophorum, but unlike bovine liver abscesses, F necrophorum biovar B was isolated more frequently than was biovar A and often in pure culture. Most of the lesions in the condemned livers were parasite-induced granulomas.