Severe outbreaks of bovine interdigital phlegmon (IP) have occurred recently in several free stall dairy herds in Finland. We studied the aetiology of IP in such herds, and the association of bacterial species with the various stages of IP and herds of various morbidity of IP. Nineteen free stall dairy herds with IP outbreaks and three control herds were visited and bacteriological samples collected from cows suffering from IP (n = 106), other hoof diseases (n = 58), and control cows (n = 64). The herds were divided into high morbidity (morbidity ≥50%) and moderate morbidity groups (9–33%) based on morbidity during the first two months of the outbreak. F. necrophorum subspecies necrophorum was clearly associated with IP in general, and T. pyogenes was associated with the healing stage of IP. Six other major hoof pathogens were detected; Dichelobacter nodosus, Porphyromonas levii, Prevotella melaninogenica, Treponema spp. and Trueperella pyogenes. Most of the samples of acute IP (66.7%) harboured both F. necrophorum and D. nodosus. We found differences between moderate morbidity and high morbidity herds. D. nodosus was more common in IP lesion in high than in moderate morbidity herds. Our result confirms that F. necrophorum subspecies necrophorum is the main pathogen in IP, but also T. pyogenes is associated with the healing stage of IP. Our results suggest that D. nodosus may play a role in the severity of the outbreak of IP, but further research is needed to establish other bacteriological factors behind these severe outbreaks.

Mycoplasma bovis is an important bovine pathogen. Artificial insemination (AI) using contaminated semen can introduce the agent into a naïve herd. Antibiotics, most often gentamycin, tylosin, lincomycin, spectinomycin (GTLS) combination are added to semen extender to prevent transmission of pathogenic bacteria and mycoplasmas. In a commercial AI straw production system with industrial scale procedures, we analyzed the mycoplasmacidal efficacy of GTLS and ofloxacin on M. bovis ATCC and wild type strain isolated from commercial AI straws. The strains were spiked at two concentrations (10⁶ and 10³ CFU/mL) into semen. Viable M. bovis in frozen semen straws was detected by enrichment culture and real-time PCR. We also compared different protocols to extract M. bovis DNA from spiked semen. None of the antibiotic protocols had any effect on the viability of either of the M. bovis strains at high spiking concentration. At low concentration, the wild type was inhibited by all other protocols, except low GTLS, whereas the ATCC strain was inhibited only by high GTLS. The InstaGene™ matrix was the most effective method to extract M. bovis DNA from semen. When there is a low M. bovis contamination level in semen, GTLS used at high concentrations, in accordance with Certified Semen Services requirements, is more efficient than GTLS used at concentrations stated in the OIE Terrestrial Code.

Several Finnish dairy herds have suffered from outbreaks of interdigital phlegmon (IP). In these new types of outbreaks, morbidity was high and clinical signs severe, resulting in substantial economic losses for affected farms. In our study, we visited 18 free stall dairy herds experiencing an outbreak of IP and 3 control herds without a similar outbreak. From a total of 203 sampled cows, 60 suffered from acute stage IP. We demonstrated that acute phase response of bovine IP was evident and therefore an appropriate analgesic should be administered in the treatment of affected animals. The response was most apparent in herds with high morbidity in IP and with a bacterial infection comprising Fusobacterium necrophorum and Dichelobacter nodosus, indicating that combination of these two bacterial species affect the severity of the disease.