An effective dry cow teat sealant will provide an external physical barrier for the teat orifice during critical times in the dry period.
Bacterial populations remain elevated on the teats throughout the dry period.
Dairy cows are susceptible to new intramammary infections (IMI) at the beginning and end of the dry period.
Dairy cows are susceptible to new intramammary infections (IMI) at the beginning and end of the dry period. Cows are naturally protected against intramammary infections during the dry period by formation of a keratin plug in the teat canal. However, time of teat canal closure varies among cows. In one study, 50% of teat canals were classified as closed by 7 days after dry off, 45% closed over the following 50-60 days of the dry period, and 5% had not closed by 90 days after dry off1a. Teats which do not form a plug-like keratin seal are thought to be most susceptible to infection. Infusion of antibiotics into the udder at drying-off has been the major management tool for the prevention of IMI, as well as treatment of IMI persisting from the previous lactation.1
However, even with the use of antibiotics, 50% of new IMI occur during the dry period1. A large percentage of new infection results from environmental organisms. This may occur because teat skin bacterial populations increase greatly at dry-off. Bacterial populations remain elevated on the teats throughout the dry period. Increased bacteria numbers are thought to result from the end of milking hygiene practices (pre- & post-dipping, udder clipping, etc.). During calving, teat skin bacterial populations increase further. This is probably a combined effect of increased exposure to environmental bacteria in calving pens and leaking colostrum that may encourage bacterial growth.
The National Mastititis Council’s Recommended Mastitis Control Program suggests using a teat sealant on dry cows exposed to a high level of environmental pathogens. An effective dry cow teat sealant will provides an external physical barrier for the teat orifice during critical times in the dry period. Timms3 has shown that when used in combination with antibiotic infusion, teat sealants can provide an additional reduction in dry period mastitis in comparison to dry cow therapy alone. Timms3 demonstrated a 46.8% reduction in new IMI for cows that received a teat sealant. The efficacy of an external teat sealant has been confirmed by Leslie2 and in subsequent trials by Timms6,7. The teat sealant is applied at dry-off, after antibiotic infusion, and again 7 to 10 days prior to calving. The teat sealant functions by preventing environmental organisms from entering the udder. Duration of adherence of the sealant to the teat, and protection of the teat orifice, are critical factors in the performance of the teat sealant.
The persistence of sealant products may vary. A large multiple-herd trial in Canada had 57.4% of teat-ends covered at 4 days post-drying-off,4 compared to 85.8% in a multi-site trial conducted in France5. In a pre-calving trial in the United States, 25% of teat-ends were covered at 4 days,6 versus 66% in the French trial5. The authors have generally observed that adherence is longer after a drying-off application than after a pre-calving application. Timms7 has suggested that an external teat sealant might be an effective substitute for dry cow antibiotic therapy in the prevention of new dry period infections. In a single field trial, no difference in new intramammary infections was observed between dipping with an external teat sealant and antibiotic therapy at dry-off7.
A different approach for the prevention of intramammary infections during the dry period is to infuse material that “short circuits” the natural sealing process at dry off. A product of this type must fill the fissures and folds within the teat canal and teat sinus to produce an effective physical barrier to the entrance of bacteria8. This approach is more invasive than the external barrier teat sealants, but has been used successfully in the field. One product of this type has been used to prevent dry period intramammary infections without use of antibiotic therapy at dry off.
Intra-mammary teat sealants
Because of the growing concern about antibiotic overuse, there is increased interest in the use of intramammary teat sealants. This is a different approach to the prevention of intramammary infections during the dry period. The product is an inert salt in a paraffin base, and it is infused directly into the teat canal. A product of this type must fill the fissures and folds within the teat canal and teat sinus to produce an effective physical barrier to the entrance of bacteria8.
This form of teat sealant has been available in Europe for some time, in combination with an antibiotic treatment. In New Zealand, the product has recently been reformulated and marketed without the antibiotic (Orbeseal - Pfizer Animal Health). Studies have found this type of teat sealant to be effective in preventing new intramammary infections during the dry period, although it appears to be more effective in animals that have low cell counts at the time of application9.
1a. Williamson, J.H., M.W. Woolford, and A.M. Day. 1995. The Prophylactic Effect of a Dry-Cow Antibiotic Against Streptococcus uberis. New Zealand Veterinary Journal 43:228.
1. Nickerson, S.L. 1998. Teat end interactions with germicides. National Mastitis Council Annual Meeting Proceedings, pg. 67.
2. Leslie, K.E., D.F. Kelton, K.J. Day,et al., Milking Management in Ontario Dairy Herds (1999); National Mastitis Council Annual Meeting Proceedings, pp. 126-127.
3. Timms, L.L., Field Trial Evaluation of a Persistent Barrier Teat Dip for Preventing Mastitis During the Dry Period (1997); J. Dairy Sci. 80:Suppl. 1, 225.
4. Lim, G.H., K.E. Leslie, D.F. Kelton, et al., An Investigation of the Factors Affecting the Adherence of a Dry Cow Teat Sealant in Commercial Dairy Herds in Ontario (2000); Personal communication
5. WestAgro data
6. T. Hemling, M. Henderson. IDF Symposium on Immunology of Ruminant Mammary Glands. 2000. p. 19
7. Timms, L.L., 2001. Field Trial Evaluations of a Novel Persistent Barrier Teat Dip for Preventing Mastitis During the Dry Period and as a Potential Substitute for Dry Cow Antibiotic Therapy. National Mastitis Council Annual Meeting Proceedings, pp.262-263.
8. Williamson, J. 2001. Strategies for Protecting the Teat at Dry Off. National Mastitis Council Annual Meeting Proceedings, pp.88-94.
9. Berry, E.A. and J.E. Hillerton. 2002. The Effect of an Intramammary Teat Seal on New Intramammary Infections. J. Dairy Sci. 85:2512-2520.