Fig 1.
Ear tip necrosis lesion scoring chart.
Photos obtained during a clinical outbreak.
Fig 2.
Heatmap of (Right and Left) ear necrosis scores throughout the experimental period of trial 1, using Staphylococcus hyicus as the inoculum.
Fig 3.
Post-inoculation rectal temperature from pigs inoculated (n = 10) with F. necrophorum and sentinels (n = 2) in Trial 2.
Horizontal bars depict group average, dotted line shows the fever threshold for pigs at this age.
Fig 4.
Representative photos depicting lesion progression from Trial 2 (F. necrophorum).
A- Control ear sham inoculated, 8 hours post-inoculation. B- Inoculated ear 24 hours post-inoculation showing subcutaneous haemorrhage. C- Inoculated ear 2 days post-inoculation showing haemorrhage and early necrosis. D and E- Inoculated ears 4 days post-inoculation, showing progressive tissue dehydration and necrosis. F- Inoculate ear 6 days post-inoculation with tissue loss, sloughed necrotic tissue.
Fig 5.
Heatmap of (Right and Left) ear necrosis scores throughout the experimental period of Trial 2, using Fusobacterium necrophorum as the inoculum delivered to the left ear of inoculated pigs (n = 10).
Score 0) no visual abnormalities; 1) edema and hyperemia visible, initial lesions, no epithelial erosion or ulceration; 2) the initial swelling erodes through the skin surface to form a scab; 3) necrotic tissue is present; 4) healed lesions with loss of ear tissue.
Fig 6.
Histopathology from ear samples collected post-mortem from pigs in Trial 2 (F. necrophorum).
A- Representative H&E stained section of the ear from a pig that developed necrosis and lost a section of the ear. Loss of epithelial coverage and ulceration is observed (black arrows), as well as granulation tissue. B- Higher magnification within the same section stained with Warthin-Faulkner revealed filamentous structures within and around the ulcerated sections, suggestive of F. necrophorum (red arrows).
Fig 7.
Post-inoculation rectal temperature from pigs inoculated (n = 9) with F. necrophorum and sentinel pigs (n = 3) from Trial 3.
Horizontal bars show group average for a given sampling point, dotted line represents the fever threshold for nursery pigs.
Fig 8.
Heatmap of (Right and Left) ear scores during the experimental period of Trial 3, with Fusobacterium necrophorum inoculated to the right ear of inoculated pigs (n = 9).
Score: 0) no visual abnormalities; 1) edema and hyperemia visible, initial lesions, no epithelial erosion or ulceration; 2) the initial swelling erodes through the skin surface to form a scab; 3) necrotic tissue is present; 4) healed lesions with loss of ear tissue.
Fig 9.
Representative lesions of porcine ear necrosis identified in Trial 3, using F. necrophorum as inoculum.
A- Inoculated ear 3 days post challenge depicting a necrotic area with inflamed borders where viable tissue is still present. B, C and D- Inoculated ear 5 and 6 days post-challenge, with necrotic tissue partially separated from viable tissue.