Dry cow products - antimicrobial infusions
Only approved commercial antibiotic products formulated specifically for dry cow therapy in single-dose containers for intramammary infusion should be used. These products contain high levels of one or more antibiotics in a slow-release base which will maintain therapeutic levels in the dry udder for a significant length of time. Further, they have been tested in field studies, meet the guidelines of the regulators, and are guaranteed to be prepared aseptically. Home remedies should not be used.
All syringes used must be for single infusion only. Unapproved products and nonstandard methods may lead to the infusion product becoming contaminated during mixing and through multiple use, and they may spread resistant organisms. Products used for dry cow therapy should be stored in accordance with good dairy farming practices and discarded when the expiration date is reached. Outdated intramammary antibiotics may have little antibacterial activity.
Most dry cow therapy products are designed to eliminate existing infections by Gram-positive bacteria, particularly Staphylococcus aureus and streptococcal infections at drying off, and to prevent new S. aureus and streptococcal infections in the early dry period. Many producers have already eliminated Streptococcus agalactiae and dramatically reduced the level of S. aureus infection in their herds.
Continued use of dry cow treatment will help to maintain a good herd udder health status. In many herds and especially where dairy cattle confinement has become more intense, a higher percentage of new infections during the dry period are caused by environmental bacteria. Most dry cow therapy products are reasonably effective against environmental streptococci, especially Streptococcus uberis, but they lack activity against Gram-negative environmental bacteria, especially the coliforms. The length of effective protection varies between products, often according to the type of antibiotic or the dose. In Europe and Australia, dry cow products providing protection up to 54 days are available. The herd veterinarian should be consulted to determine which dry cow product should be used.
Dry cow products - internal sealant infusions
Sealing of the teat canal by the natural keratin plug that forms during the dry period is the primary natural component protecting against new intramammary infection in the late dry period. Potential damage to that protection is one reason why repeated infusions are not recommended. It has been documented that a significant proportion of quarters experience long delays or outright failure to form a complete keratin plug during the dry period, putting these quarters at increased risk for experiencing new mastitis infections. One study has reported that this risk is increased in cows producing high levels of milk at dry off.