Interpretive summary
Sole ulcers affect dairy cow immune status by O'Driscoll et alDairy cows afflicted with sole ulcers are often clinically lame, and experience pain and impaired welfare. However little is known of the cows' stress and immune response to sole ulcers. This study demonstrated that cows that are affected with sole ulcers, and clinically lame, had a different leukocyte gene expression profile to healthy cows. They also had higher concentrations of the stress hormone, cortisol, the endogenous precursor steroid hormone -DHEA, and the various metabolites that are suggestive of systemic inflammation and stress.
ABSTRACTSole ulcers are one of the most severe lameness causing pathologies for dairy cows and are associated with abnormal behaviour and impaired production performance. However, little is known about how or whether lameness caused by sole ulcers affects the cow systemically. This study compared haematology profile, leukocyte gene expression, and physiological responses (metabolite, cortisol, the endogenous steroid hormone -DHEA, and haptoglobin concentrations) of cows with sole ulcers and healthy cows. Twelve clinically lame cows (LAME) were identified as having at least one sole ulcer, and no other disorder and matched with a cow that had good locomotion and no disorders (SOUND), using days in milk, liveweight, body condition score and diet. Blood samples were taken from all 24 cows within 24h of sole ulcer diagnosis. Leukocyte counts were obtained using an automated cell counter, cortisol and DHEA concentration by ELISA, and plasma haptoglobin (Hb), urea, total protein, creatine kinase and glucose were analysed on an Olympus analyser. Expression of 16 genes associated with lameness or stress were estimated using qRT-PCR. Data were analysed using the Mixed procedure in SAS (v 9.3). LAME cows had a higher neutrophil %, a numerically lower lymphocyte %, and tended to have a higher neutrophil:lymphocyte ratio than SOUND. Serum cortisol and DHEA concentrations were higher in LAME than in SOUND cows. LAME cows also tended to have higher haptoglobin and glucose levels than SOUND, as well as higher protein yet lower urea levels. SOUND cows tended to have higher relative expression of the gene coding for colony stimulating factor 2 than LAME, but in all other cases where differences were detected in cytokine gene expression (IL-1α, IL-1β, CXCL8 and IL-10), relative gene expression in SOUND cows tended to be, or was, lower than in LAME.Relative expression of MMP-13, GR-α, Fas, haptoglobin and CD62L were, or tended to be, higher in LAME than SOUND cows. A high neutrophil:lymphocyte ratio in combination with higher cortisol levels in cows with ulcers is indicative of physiological stress. Moreover, increased DHEA and a higher cortisol:DHEA ratio, as well as a tendency for higher haptoglobin levels and increased 5 haptoglobin mRNA expression are indicative of systemic inflammation. Increased cytokine mRNA expression indicates activation of the immune system compared with healthy cows. Increased express...