Efficacy of chlorhexidine as a postmilking teat disinfectant for the prevention of bovine mastitis during lactation

A natural exposure trial was conducted for 12 mo in a herd of 150 lactating Jersey cows to determine efficacy of a .35% chlorhexidine teat dip containing a glycerine emollient for the prevention of bovine intramammary infections. Right teats of cows were dipped in the experimental teat dip after milking machine removal and left teats were not dipped. The herd was free of Streptococcus agalactiae and had a low prevalence of Staphylococcus aureus. Most new major pathogen intramammary infections resulted from Streptococcus species, primarily Streptococcus uberis and Streptococcus dysgalactiae. New infections by Streptococcus species were significantly lower in teats dipped in chlorhexidine than in undipped teats. Overall efficacy of the chlorhexidine teat dip against major mastitis pathogens was 50%. The experimental teat dip also reduced coagulase-negative Staphylococcus species infections 49.0% and Corynebacterium bovis infections 65.2%. Overall efficacy against minor mastitis pathogens was 54.0%. No irritation or chapping of teats dipped in the experimental teat dip was observed.     

Evaluation of a chlorous acid-chlorine dioxide teat dip under experimental and natural exposure conditions

A postmilking teat dip containing chlorous acid-chlorine dioxide was evaluated by experimental challenge and in two herds under natural exposure. The test product had an efficacy of 78.9% against Staphylococcus aureus and 52.5% against Streptococcus agalactiae in the experimental challenge trial. The product was compared with a 1% iodine product in a 15-mo natural exposure study. Post-dipping with chlorous acid-chlorine dioxide reduced incidence of udder infection by major mastitis pathogens 36.1% when data were combined from the two herds. The 1% iodine and the chlorous acid-chlorine dioxide products were not equivalent for major mastitis pathogens; the test product was more effective. Incidence of udder infection by environmental mastitis pathogens was reduced 36.8% in both herds combined. Efficacy of the two teat dips was equivalent for environmental pathogens.     

Efficacies of chlorine dioxide and lodophor teat dips during experimental challenge with Staphylococcus aureus and Streptococcus agalactiae

We tested two postmilking teat dips for efficacy against Staphylococcus aureus and Streptococcus agalactiae using experimental challenge procedures recommended by the National Mastitis Council. The chlorine dioxide teat dip that contained 0.7% sodium chlorite reduced the number of new intramammary infections (IMI) caused by Staph. aureus by 86.6% and reduced new IMI caused by Strep. agalactiae by 88.4%. The 0.5% iodophor teat dip reduced the number of new IMI caused by Staph. aureus by 92.9% and reduced the number of new IMI caused by Strep. agalactiae by 43.4%. Teat skin and teat end conditions were evaluated before and after the study, and no deleterious effects were noted among dipped quarters compared with undipped control quarters for either teat dip.     

Evaluation of a postmilking teat disinfectant containing a phenolic combination for the prevention of mastitis in lactating dairy cows

A trial was conducted for 12 months in a herd of 120 Holstein cows in order to determine the efficacy of a teat disinfectant, which contained a phenolic combination, for the prevention of bovine intramammary infections during lactation. Postmilking teat disinfection was compared to a negative control using a split-udder experimental design. The percentage of quarters newly infected by mastitis pathogens was 45% lower in mammary glands with teats that had been dipped in the experimental teat disinfectant after milking than it was in undipped controls. New infections caused by Streptococcus uberis, Staphylococcus aureus, coagulase-negative Staphylococcus species, and Corynebacterium bovis were significantly lower in mammary glands with teats that had been dipped in the experimental teat disinfectant than in undipped controls. No statistical differences in the incidence of clinical mastitis between treatment groups were observed. No irritation or chapping of teats dipped in the experimental teat disinfectant were observed. The results of this study suggest that the experimental teat disinfectant containing a phenolic combination is an effective postmilking teat disinfectant for use in the prevention of new intramammary infections by both contagious and environmental mastitis pathogens.     

Short communication: disinfectant containing a complex of skin conditioners

The efficacies of 2 new teat dip formulations were tested against experimental challenge by contagious mastitis pathogens Staphylococcus aureus and Streptococcus agalactiae over a 12-wk period. Formulations contained an iodine complex (0.5 or 1.0% iodine) and skin conditioning agents (propylene glycol, polyvinylpyrridone, glycerine, lanolin, allantoin, and aloe). Percentage reduction (dipped vs. control mammary quarters) in new contagious mastitis pathogen intramammary infections for the 0.5 and 1.0% iodine dips was 65.4 and 84.5, respectively. Both dips were significantly effective in reducing new contagious intramammary infections. Teat skin scores and teat end scores varied over time but were virtually identical for both treated and control teats, for both treatments. Thus, both dips were effective in reducing new contagious mastitis infections without untoward effects on teat skin condition.     

Efficacy of two acidified chlorite postmilking teat disinfectants with sodium dodecylbenzene sulfonic acid on prevention of contagious mastitis using an experimental challenge protocol

Two acidified sodium chlorite postmilking teat disinfectants were evaluated for efficacy against Staphylococcus aureus and Streptococcus agalactiae by using National Mastitis Council experimental challenge procedures. The effect of these teat dips on teat skin and teat end condition was also determined. Both dips contained 0.32% sodium chlorite, 1.32% lactic, and 2.5% glycerin. Dips differed in the amount of sodium dodecylbenzene sulfonic acid (0.53 or 0.27%) added as a surfactant. Both dips significantly reduced new intramammary infection (IMI) rates compared with undipped controls. The dip containing 0.53% dodecylbenzene sulfonic acid reduced new IMI by Staph. aureus by 72% and Strep. agalactiae by 75%. The dip containing 0.27% dodecylbenzene sulfonic acid reduced new IMI by Staph. aureus by 100% and by Strep. agalactiae by 88%. Changes in teat skin and teat end condition for treatment and control groups varied in parallel over time. Teats treated with either teat dip had higher mean teat skin and teat end scores than control teats at some weeks. However, teat skin and teat end condition did not tend to change from the start to the completion of the trial. Application of the two new postmilking teat dips was effective in reducing new IMI from contagious mastitis pathogens. (Key words: teat dip, contagious mastitis, chlorous acid)     

Reduction of mastitis caused by experimental challenge with Staphylococcus aureus and Streptococcus agalactiae by use of a quaternary ammonium and halogen-mixture teat dip

A teat-dip formulation containing sodium dichloro isocyanuric acid, bronopol, and quaternary ammonium was tested for efficacy against Staphylococcus aureus and Streptococcus agalactiae intramammary infections (IMI) using an experimental challenge model. Sixty-two Jersey cows from the Hill Farm Research Station (Homer, LA) were used in an 8-wk controlled infection trial to evaluate the teat dip. During the afternoon milking, Monday through Friday for 8 wk, all teats of each cow were immersed to a depth of approximately 25 mm in a challenge suspension containing approximately 5 x 10(7) cfu of Staphylococcus aureus and approximately 5 x 10(7) cfu of Streptococcus agalactiae immediately after milking machines were removed. Immediately after challenge, the distal 25 mm of two contralateral teats were dipped with the experimental teat dip; the remaining two teats served as undipped controls. The experimental teat dip reduced the number of new Staph. aureus IMI by 70.9% and reduced the number of new Strep. agalactiae IMI by 60.0%. Teat end and teat skin condition were characterized as normal and without irritation at the completion of the study. The combination of the three germicides in this experimental teat dip is unique and an effective formulation without adverse effects on condition of teat ends or teat skin.     

Germicidal teat dip in a herd with low prevalence of Streptococcus agalactiae and Staphylococcus aureus mastitis

Effectiveness of an iodophor teat dip in reducing new intramammary infection and clinical mastitis was tested in a herd free of Streptococcus agalactiae and with a low prevalence of Staphylococcus aureus infections. In this 6-mo study with an average of 152 lactating cows on trial on sampling dates, right rear and left front teats were dipped after each milking while right front and left rear teats were undipped controls. Teat dipping significantly reduced new infections by Staphylococcus aureus, streptococci (other than Streptococcus agalactiae), coagulase-negative staphylococci, and Corynebacterium bovis and reduced clinical cases caused by infections established during the trial. However, the dip did not reduce new infections or clinical mastitis caused by coliform bacteria. Therefore, use of a germicidal dip is recommended for herds with a low prevalence of Streptococcus agalactiae and Staphylococcus aureus, but the practice should not be expected to control coliform mastitis.     

Evaluation of experimental teat dip containing sodium chlorite and lactic acid by excised teat assay

An experimental teat dip containing sodium chlorite and lactic acid, diluted in water, was evaluated by excised teat protocol. The teat dip was tested against 21 microorganisms. Included were: Staphylococcus aureus, Streptococcus agalactiae, Streptococcus dysgalactiae, Streptococcus uberis, Escherichia coli, Klebsiella oxytoca, Klebsiella pneumoniae, and Pseudomonas aeruginosa. Numerous strains were tested for strain differences. Environmental bacteria were included because of their increasing importance as a cause of bovine mastitis. All excised teats were dipped in a bacterial suspension containing about 1 X 10(8) cfu/ml. Negative control teats were not dipped in a germicidal compound. Positive controls were dipped in 1% iodophor. Effectiveness of the experimental teat dip was expressed as the percent reduction in mean log of bacteria recovered from dipped teats as compared to numbers recovered from control teats. The sodium chlorite - lactic acid dip caused a greater percent log reduction than iodophor for 14 of 21 strains tested. However, differences were generally slight. The experimental teat dip appeared effective against Gram-negative bacteria. Some differences in percent log reduction were observed between strains of the same species. Lowest effectiveness and greatest strain variation were observed with Staphylococcus aureus for both dips tested.     

Effects of a 1.94% sulfonic acid teat dip and a 1% iodophor teat dip on teat canal infections in lactating dairy cows

Sixty-three cows were used in a natural exposure trial for 1 yr to determine the effects of a 1.94% linear dodecyl benzene sulfonic acid and a 1% iodophor teat dip on teat canal and intramammary infections. Overall, total teat canal infections increased 28.9% and total intramammary infections increased 30% in quarters dipped with the linear dodecyl benzene sulfonic acid compared with a 14.3% increase in teat canal infections and a 17.4% decrease in intramammary infections for the iodophor group. Higher frequencies were observed for teat canal and intramammary infections caused by Staphylococcus epidermidis in the linear dodecyl benzene sulfonic acid group. Staphylococcus hyicus was the predominant organism isolated from teat canal and intramammary infections in the iodophor group. No difference was observed between the two teat dips in the persistence of Staphylococcus aureus teat canal infections. A greater number of S. hyicus teat canal infections persisted in the iodophor group, whereas teat canal infections produced by S. epidermidis and Staphylococcus xylosus persisted longer in the sulfonic acid group. Results of this study indicated that use of a linear dodecyl benzene sulfonic acid teat dip for 1 yr was not associated with increased S. aureus teat canal infections and intramammary infections. However, linear dodecyl benzene sulfonic acid appeared to affect the distribution of coagulase-negative staphylococci isolated from teat canal infections and intramammary infections.     

Evaluation of 1.6% phenol as a premilking and postmilking teat dip in preventing new bovine intramammary infections

We evaluated the effectiveness of a 1.6% phenol-based teat dip using both a teat skin assay and natural exposure field trial. A teat skin assay was conducted to ascertain the concentration of phenol + phenate to be used in the field study. One percent and 0.5% iodine, and 0.5, 1.1, and 1.6% phenol + phenate were compared using Escherichia coli and Staphylococcus aureus. Logarithmic reductions for S. aureus were 2.2 and 2.8 for 0.5 and 1% iodine, and 1.3, 2.1, and 2.8 for 0.5, 1.1, and 1.6% phenol + phenate, respectively. Logarithmic reductions for E. coli were 3.3 and 3.8 for 0.5 and 1% iodine, and 1.2, 1.9, and 2.6 for 0.5, 1.1, and 1.6% phenol + phenate, respectively. A concentration of 1.6% phenol + phenate was chosen as experimental teat dip, and 0.5% iodine served as control. The field study was conducted at Beltsville (n = 185) and Clarksville (n = 100) dairy herds using a split herd design. Teat dips were used premilking and postmilking for 12 mo. The number of new intramammary infections (IMI) for the Beltsville herd in iodine and phenol + phenate teat dipped cows were: 29 and 35 for major pathogens, and 81 and 72, for minor pathogens. For the Clarksville herd, number of new intramammary infections in iodine and phenol + phenate teat dipped cows was 9 and 10 for major pathogens, and 50 and 60 for minor pathogens. Rates of IMI per quarter day per lactation were not different for either herd or when herd data were combined. The number of clinical mastitis cases per 100 cows per month were similar in both treatments. The incidences of new IMI and clinical mastitis were similar using both dips.     

Comparison of teat dips with differing iodine concentrations in prevention of mastitis infection

Six commercial dairy herds were used to test the relative efficacy of three concentrations of iodine as a teat dip over 12 mo. Concentrations were .1, .25, and 1% iodine with free iodine contents of 3.5, 4.0, and 1.0 ppm. Two concentrations were compared in each herd. The greatest number of new infections (71) occurred in approximately 120 cows whose teats were dipped with the 1% iodine dip, and the fewest (52) occurred in a similar number of cow quarters dipped in .1% iodine; however, differences were not significant. Clinical mastitis was highest in the 1% group. If all clinical mastitis were the result of infection, even if bacteria were not isolated from the pretreatment sample or from samples collected at the start of the study and those quarters were added to the totals, then reduction of new infection with the .1% product would be significant.     

Evaluation of linear dodecyl benzene sulfonic acid as a teat dip in a commercial dairy

A postmilking teat dip containing 1.94% linear dodecyl benzene sulfonic acid was evaluated for approximately 6 mo on a commercial dairy farm that milked an average of 75 cows. Sixteen Staphylococcus aureus infections were diagnosed, 12 in the undipped control quarters and 4 in the dipped. Incidence of intramammary infection with Staphylococcus aureus was reduced 68.1%. Seventy-five infections were diagnosed as micrococci, 42 in control and 33 in the dipped group, a 23.6% reduction. A total of 37 Corynebacterium sp. infections were diagnosed, 21 and 16 in control and dipped groups, a 25.8% reduction. Teat skin condition did not change during the study.     

Use of latex teat dip with germicide during the prepartum period

The efficacy of an acrylic latex barrier teat dip with germicide on new infections at parturition was tested on 113 cows and heifers during the prepartum period. A split udder design was used in which right quarters were undipped controls and left quarters were dipped with latex dip once daily for approximately 14 d prior to parturition. Distal streak canal swabs were taken from all quarters prior to the beginning of dipping, and all cows were quarter sampled in duplicate at drying off, parturition, and the first 5 consecutive wk of lactation. All quarters received antibiotic therapy at drying off. Excluding infections detected by distal streak canal swabs, the number of new infections at parturition in control and dipped quarters was 32 and 36. New infections at parturition in control and dipped quarters were Staphylococcus aureus, 2 and 2; coagulase-negative staphylococci, 8 and 9; stretptococci, 10 and 12; coliforms, 8 and 8; and others, 4 and 5. Differences were not significant. These results suggest no benefit to use of prepartum latex teat dip with germicide on new infections at parturition.     

Efficacy of a latex teat sealer

In the first of two experiments, efficacy of a latex teat sealer product was tested under field conditions on 32 cows that had one side of the udder dipped with the test product and the other left as the control. Number of new coliform, staphylococcal, or streptococcal infections in treated quarters was not reduced from controls. In a second experiment, effectiveness of this product as a protective sealer was investigated on six cows dip challenged with a broth containing 1 million Escherichia coli/ml. On sealed teats the challenge was applied on top of the dried film. The challenge organism was recovered from 33% of treated quarters and 42% of control quarters 6 h after exposure. Organisms were recovered from none of the quarters by 31 h postchallenge.     

Efficacy evaluation of two new teat dip formulations under experimental challenge

Two new teat dip formulations were evaluated against Streptococcus agalactiae and Staphylococcus aureus in half-udder, experimental challenge studies. The first product contained a combination of 1.9% linear dodecyl benzene sulfonic acid - .55% iodophor. Incidence of infection was reduced 52.7 and 70.7% for Streptococcus agalactiae and Staphylococcus aureus in dipped quarters compared to undipped controls. The second formulation was a barrier-type product consisting of milk protein solubilized with lauryl sulfate, a surface active detergent and 4.8% glycerin. Rates of infection were reduced 60.3 and 67.9% for Streptococcus agalactiae and Staphylococcus aureus.     

Efficacy of a new premilking teat disinfectant containing a phenolic combination for the prevention of mastitis.

A teat disinfectant containing a phenolic combination was evaluated in a natural exposure study in two dairy research herds. Premilking teat disinfection was compared with a negative control using a split-udder experimental design. In both herds, premilking and postmilking teat disinfections with the phenolic combination were significantly more effective in preventing new intramammary infection (IMI) than was postmilking teat disinfection only. Clinical mastitis and new IMI by Streptococcus uberis, Streptococcus dysgalactiae, Gram-negative pathogens, and coagulase-negative Staphylococcus species were significantly lower in quarters of cows with teats predipped and postdipped than in quarters with teats postdipped only. No chapping or teat skin irritation was observed. Premilking teat disinfection with the phenolic combination in association with good udder preparation and postmilking teat disinfection can further reduce the occurrence of new IMI by numerous mastitis pathogens during lactation.     

Evaluation of the efficacy of an internal teat sealer during the dry period

The efficacy of an internal dry period teat sealer containing bismuth subnitrate (Product A; Teatseal, Cross Vetpharm Group Ltd, Ireland) was compared with a long-acting antibiotic preparation containing cephalonium (Product B; Cepravin Dry Cow, Schering-Plough Ltd, UK), by assessing the number of new intramammary infections (IMI) acquired during the dry period and the number of cases of clinical mastitis during the first 100 d of lactation. Selection of study animals was based on historical data. No cases of clinical mastitis and all routine cow level somatic cell counts <200,000 cells/ml during the previous lactation were used to select cows likely to be uninfected with a major pathogen at drying off. Compared with the antibiotic tube, quarters that received the teat sealer acquired significantly fewer new IMI caused by Escherichia coli, all Enterobacteriaceae, and all major pathogens combined. There was no significant differences in the number of IMI caused by any other major pathogen. There was no significant difference in the severity or number of quarter or cow cases of clinical mastitis between product groups. Sixty quarters (3.2%) were infected with major pathogens at drying off, 27 (2.9%) in teat sealer and 33 (3.5%) in antibiotic tube cows. The dry period cure rate was not significantly different (63% product A, 70% product B). This is the first controlled study to demonstrate the efficacy of an internal bismuth teat sealer in protecting quarters against new dry period IMI caused by major mastitis pathogens, particularly environmental organisms, under UK field conditions.     

Intramammary infections and teat canal colonization with coagulase-negative staphylococci after postmilking teat disinfection: species-specific responses

Coagulase-negative staphylococci (CNS) are the most common pathogens associated with intramammary infections (IMI) in dairy cows. We hypothesized that postmilking teat disinfection would reduce microbial colonization of the teat canal and thus reduce the prevalence of IMI caused by certain CNS species. The efficacy of iodine postmilking teat dip was tested against CNS colonization of the teat canal, and incidence of IMI was measured. Using an udder-half model, 43 Holstein cows at the Washington State University Dairy were enrolled in the trial; postmilking teat dip was applied to one udder-half, treatment (TX), and the remaining half was an undipped control (CX). Teat canal swabbing and mammary quarter milk samples were taken in duplicate once a week for 16 wk for microbial culture. Isolates from agar cultures were presumptively identified as CNS and then speciated using PCR-RFLP and agarose gel electrophoresis. Colonization of the teat canal and IMI by CNS were assessed. Thirty CNS IMI were diagnosed and the number of new IMI in CX quarters (21) was significantly greater than that in TX mammary quarters (9). The majority of CNS IMI were caused by Staphylococcus chromogenes (30%) and Staphylococcus xylosus (40%), and the latter were appreciably reduced by teat dip. Except for S. xylosus, an association was observed between teat canal colonization and IMI by all CNS species in this study, in which the majority of IMI were preceded by teat canal colonization. The total number of CNS IMI was greater for CX group cows compared with TX group cows. However, the effect of disinfection on IMI did not appear to be the same for all CNS species.     

Control of new intramammary infection at calving by prepartum teat dipping

Cows were subjected to teat dipping in a commercial iodophor germicide twice daily for at least 7 days immediately before calving to assess efficacy of the practice in reducing new intramammary infection at calving. In a cold season and in a warm season, groups of about 35 cows successively calving were treated and were compared with similarly sized and selected control groups. There were no advantages for teat dipped over control cow groups for incidence of new intramammary infections at calving, for new infections that persisted for longer than 14 days after calving, or for new infections that required antibiotic therapy. Incidence of new infection in warm weather (27.3% of quarters) was twice that in cool weather (13.6%). The most frequently isolated pathogens were coagulase-negative staphylococci and Streptococcus uberis. Staphylococcus aureus infections were most likely to persist into the new lactation (83%) than were infections by other pathogens (38 to 57%).