Dry cow therapy (DCT), an infusion of antibiotics into the mammary gland at the end of lactation, is
widely used for the control of intra-mammary infections (IMI) in the dairy cow. However, increased public
health concerns about the use of antibiotics, has led to the search for alternatives to the routine use of
antibiotics during drying off. In the present study the effects of three dry cow treatments, two types of
DCT and a teat-sealant, on the development of new IMI and clinical mastitis were investigated in 240
cows belonging to two herds (Herd A and Herd B). In Herd A, 60 cows were given one type of DCT (Cloxacillin)
and the other 60 cows were given another type of DCT (Framycetin). In Herd B, 60 cows were
given teat-sealant and the other herd were not given any treatment. There were significantly more
new IMI at calving in control cattle compared to those given teat-sealants (p < 0.001) and there were
more cases of clinical cases of mastitis in the control group. The number of clinical cases detected in cows
given teat-sealant in Herd B were not significantly different from those detected in cows in Herd A given
Cloxacillin or Framycetin.