title: Efficacy of a novel internal dry period teat sealant containing 0.5% chlorhexidine against experimental challenge with Streptococcus uberis in dairy cattle.
abstract: The incidence of clinical mastitis and infection status at calving was assessed in quarters treated with 1 of 2 internal teat sealants at the time of dry off. Two contralateral quarters per cow (n=63 cows) were treated with a sealant that contained 0.5% chlorhexidine; the other quarters were treated with a commercial teat sealant. Ten cows were untreated (controls). On d 2, 4, and 16 after dry off, cows were challenged with Streptococcus uberis S210 strain. Cows were examined daily for 34 d after drying off and cases of clinical mastitis were recorded. Milk samples were collected for culture from any quarters that developed clinical mastitis during the first 34 d after drying-off and from all quarters on d -5 and 0 relative to treatment and at the first and twentieth milking after calving. The incidence of clinical mastitis during the examination period was lower in treated quarters (n=7/252; 1.5%; lower incidence for those treated with chlorhexidine-containing teat sealant n=3/126; 1.2%) than in untreated quarters (n=13/40; 26.8%). The protection against intramammary infection after calving, adjusted for the effect of cow, was higher in quarters treated with the novel teat sealant (89/105; 15.2%; 95% CI=9.6-23.4) than in those treated with the commercial teat sealant (71/104; 31.7%; 95% CI=23.5-41.3) and untreated controls (6/28; 78.6%; 95% CI=59.8-90.0), respectively. Quarters treated with teat sealants were less likely to have an intramammary infection after calving and had a lower incidence of clinical mastitis during the early dry period than did untreated controls in this challenge study.
authors.affiliation: Institute of Veterinary, Animal and Biomedical Sciences, Massey University, Private Bag 11222, Palmerston North 4442, New Zealand. k.r.petrovski@massey.ac.nz
authors.forename: K R
authors.initials: KR
authors.lastname: Petrovski
authors.forename: A
authors.initials: A
authors.lastname: Caicedo-Caldas
authors.forename: N B
authors.initials: NB
authors.lastname: Williamson
authors.forename: N
authors.initials: N
authors.lastname: Lopez-Villalobos
authors.forename: A
authors.initials: A
authors.lastname: Grinberg
authors.forename: T J
authors.initials: TJ
authors.lastname: Parkinson
authors.forename: I G
authors.initials: IG
authors.lastname: Tucker
mesh_terms: D000818:Animals; D000900:Anti-Bacterial Agents / Q000627:therapeutic use*; D002417:Cattle; D002710:Chlorhexidine / Q000627:therapeutic use*; D005260:Female; D008321:Mammary Glands, Animal / Q000382:microbiology / Q000502:physiology; D008414:Mastitis, Bovine / Q000453:epidemiology / Q000517:prevention & control*; D049590:Postpartum Period; D013290:Streptococcal Infections / Q000453:epidemiology / Q000517:prevention & control / Q000662:veterinary*; D013291:Streptococcus / Q000145:classification / Q000187:drug effects*
chemical_list: D000900:Anti-Bacterial Agents; D002710:Chlorhexidine