Mastitis control in bred heifers: Use of dry cow therapy and teat sealant for curing existing intramammary infections and preventing new ones

Presence of mastitis in pregnant as well as unbred dairy heifers can adversely affect the development of milk-producing tissues, leading to less than maximal milk production and increased SCC during their first lactation. Use of nonlactating cow therapy or teat sealants have been beneficial in curing existing IMI and preventing new IMI from developing. When used together, the combination of the two products may be more effective than either alone in controlling mastitis in these young dairy animals. To examine this, 4 quarters of each of 76 pregnant heifers were treated randomly 30 to 60 days prepartum as follows: 1) untreated control, 2) dry cow therapy, 3) teat sealant, or 4) dry cow therapy + teat sealant. Results demonstrated that compared to the spontaneous cure rate in untreated controls (55.2%), treatment with dry cow therapy (100%), teat sealant (85.7%), or dry cow therapy + teat sealant (96.1%) resulted in greater (P < 0.001) cure rates in quarters infected prepartum with Staphylococcus aureus or CNS. The reason for the 85.7% cure rate in teat sealant-treated quarters remains unclear. Additionally, SCC 3 d after calving were lower (P < 0.05) in quarters previously infected and cured, that were treated with dry cow therapy (914 x 10 3 /mL), teat sealant (587 x 10 3 /mL), and dry cow therapy + teat seal (534 x 10 3 /mL), compared with untreated controls (1638 x 10 3 /mL). Although the prevention rate against new IMI was similar for control quarters (95.9%) and those receiving dry cow therapy (92.2%), teat sealant (97.9%), and the combination of dry cow therapy + teat sealant (95.9%), it is recommended to implement an udder health program that incorporates treating all quarters with dry cow therapy to cure existing IMI plus a teat sealant to prevent new IMI.