ST. CLOUD, Minn. —Mastitis management is considered to be most important in our lactating cows. Heifers and dry cows are sometimes overlooked, which can be detrimental to future milk production. 

Of the two groups, heifers are most often ignored when it comes to mastitis management. However, taking the time to manage your pregnant heifers for mastitis really does matter. Milk-producing tissues in the udder undergo the most development during the first pregnancy. Mastitis during this time of development can cause permanent damage and lead to reduced lifetime production.

There are several causes of mastitis in heifers. Bacteria that are present on the udder skin surface can enter through the teat orifice. If your calves suckle on each other, the bacteria from their mouths can transfer onto the teats. There is also the threat of bacteria that are present in a dirty environment — including those on biting flies which may congregate on teat ends.

When it comes to fighting bacteria, the most important thing you can do is keep the environment clean.  Regularly remove manure, change bedding, and check that the pen heifers are in is dry. Cleanliness is key for all groups of animals on your dairy, and it’s a major component in mastitis prevention. One additional thing to watch for is calves sucking on each other. If you notice it regularly or with a specific calf, take steps to prevent it from happening — such separating the problem calf from the rest of the group. 

If a heifer does come down with mastitis, you are able to treat it. Heifers can be treated during any of their three trimesters without any effect on calving. However, treatment should not be administered within 45 days of expected calving date. When treating heifers, it is best to use a non-lactating cow product. You should always consult your veterinarian before administering any sort of mastitis treatment to a heifer.

Dry cow mastitis management is just as if not more important than it is for your heifers. Fifty to 60 percent of all new infections caused by environmental pathogens occur during the dry period. In addition, over 50 percent of clinical coliform mastitis events in the first 100 days in milk originated during the dry period.  Mastitis contracted during the dry period can result in an estimated loss of $200 per cow per year.

Causes of mastitis in dry cows are similar to those in heifers. Environmental organisms can infect the cow during lactation and/or during the dry period. Included in that is the spread of mastitis-causing bacteria on biting flies that congregate on teat ends. Another cause can be contagious organisms that spread through the herd. Another risk factor could include the cow’s lactation number, if she had a high milk yield at dry off, and the method used for drying off.  Risk factors related to the udder quarter include teat end exposure to bacteria, teat end condition, and the timely formation of the keratin plug. 

There are several prevention measures for dry cow mastitis.  First, and as always, maintaining a clean environment for your dry cows is key.  Cows with known infections should be separated from the rest of the group to prevent transfer of contagious pathogens.  As flies can be a threat to udder health, using an effective fly management program can also help reduce instances of mastitis.  Lastly, maximize immune defenses with vaccinations that have gram negative core antigens. 

Many options are available for dry cow mastitis treatment.  The first is an intramammary infusion at dry off.  This will eliminate existing infections and prevent new infections early in the dry period.  However, these infusions will not prevent infections caused by resistant bacteria.  They are also not effective against infections that occur in the late dry period. 

Another option is an internal teat sealant. They are insoluble in milk and thus have excellent persistence.  Internal sealants can be hand-stripped out of the quarter after calving.  If they aren’t stripped out in time, they can be safely ingested by the calf.  Lastly, there are no antimicrobial properties or residue issues with internal teat sealants. There are also external teat sealants which can be used.  These are made of a plastic polymer and form a physical barrier around the teat.  They are easy to apply, dry quickly, and are non-irritating and non-toxic.  External sealants will shed off the teat in 3-7 days.  For full benefit, external teat sealants should be applied at dry off, and then re-applied at 10 days before calving.      

This article was submitted by University of Minnesota Extension.