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PubMed1979

Common mammary pathogens and factors in infection and mastitis.

Inflammation of the mammary gland, commonly known as mastitis, is considered a complex disease in view of its complexities of etiology, pathogenesis, sequela, therapy, and related aspects. The disease of most concern is the one produced by pathogenic microorganisms. However, as a prerequisite the pathogen must not only enter the mammary gland but also be able to survive and multiply in numbers sufficient to produce pathogenic effects. The normal bovine mammary gland is protected from such attacks by several anatomic and biologic armamenta which must be overcome by the invading pathogens. Organisms involved in causation of mastitis vary in their habitat, virulence, and susceptibility to host barriers. Similarly cows vary in their resistance to microbial entry into the mammary gland and subsequent response to overcome the infection. Only a few organisms, however, need to survive in the milieu of the mammary gland to produce mastitis. This paper is a general discussion of these aspects concerning bovine mastitis in relation to common mammary pathogens.

Animals↗
PubMed1981

Variation in Wisconsin Mastitis Test Scores of bucket milk samples and relationship to bacterial infections.

Sources of variation in the Wisconsin Mastitis Test were studied in 4739 bucket milk samples from 111 cows in one herd during 103 days. Quarters of cows were classified infected or uninfected through bacteriologic assays of quarter milk samples. Quarters were uninfected in 70.4% of the cow-quarter-days and infected with Staphylococcus aureus and Streptococcus agalactiae in 1.4 and .9% of the quarter samples. Scores of all cow-days averaged 8.5. Wisconsin Mastitis Test scores of cow-days having no pathogens averaged 5.8. Correlation of duplicate samples was .97. Repeatability of monthly tests was .67. Days within month of lactation, month within age group, cow within age, and age differed. Older cows averaged higher Wisconsin Mastitis Test scores. Scores for uninfected cow-days did not differ with age. Scores were higher by 5.5 units in cows with infected quarters than in those with no infected quarters. The increase was greater with S. aureus or S. agalactiae present than with less virulent pathogens. In a cost-utility analysis, Wisconsin Mastitis Test was inefficient in detecting infected cows with a single test.

Animals↗
PubMed1981

Application of programmable calculators to Mastitis control programs.

Three programs pertaining to subclinical mastitis losses and control are described for use in handheld programmable calculators. Subclinical mastitis losses are calculated on the basis of lost milk estimates for California Mastitis Test evaluations. A cost profile for control programs using costs of single use towels, teat dips, and dry cow treatment is described. The cost-benefit value of a mass lactating cow antibiotic treatment regimen is presented. The programs quickly calculate the magnitude of the present subclinical mastitis loss, estimate the cost of control programs, and present information to aid in deciding whether to treat all the infected cows during lactation in an effort to reduce herd infection. User instructions and program listings are included.

Animals↗
PubMed1982

Effectiveness of educational efforts in implementing mastitis control procedures in commercial dairy herds.

One hundred-fifty diarymen in north-eastern Ohio, whose herds had a history of persistently high Wisconsin Mastitis Test scores, were invited to participate in this project, with 43 agreeing to do so. These dairymen were divided into two experimental groups and one control group to determine the effectiveness of two intensities of educational effort on adoption of mastitis control procedures and to demonstrate the effectiveness of mastitis control recommendations. A teat dipping and dry cow therapy program was adopted by more herds in the group with intense educational effort than in the intermediate or control group. Percents of herds in each group utilizing this program in 1977 (start of project), 1978, and 1979 were 8, 75, and 92 for the intense group; 30, 50, and 50 for the intermediate group; and 10, 27, and 27 for the control group. Prevalence of infection declined more rapidly in the intense group with 42, 28, and 24% of cows infected; 39, 25, and 30% in the intermedia, and 56, 35, and 42% in the control group in 1977, 1978, and 1979. Those herds adopting a teat dipping and dry cow therapy program had infection prevalence of 41, 25, and 20% of cows; bulk tank Wisconsin Mastitis Test scores of 15.5, 14.7, and 11.4; and milk production per cow per day of 18.4, 18.4, and 17.5 kg in 1977, 1978, and 1979.

Animals↗
PubMed1983

Mastitis control: a discussion.

Methods of mastitis control that are effective against Streptococcus agalactiae and Staphylococcus aureus have been developed and proven successful. These control procedures, however, are not as effective against the environmental pathogens. Environmental pathogens are predominantly the coliform bacteria and species of streptococci other than Streptococcus agalactiae. The total extent of their present involvement in mastitis is not well documented, and this is due in part to differences in the nature of infection by environmental pathogens compared to Streptococcus agalactiae and Staphylococcus aureus infections. Concern regarding the importance of environmental pathogens in mastitis is increasing. This concern is based, first, on current trends of dairy cattle housing and management that increase exposure to teat ends to environmental pathogens and, second, on a reduction of prevalence of Streptococcus agalactiae and Staphylococcus aureus infected quarters. The latter is a result of the effectiveness of postmilking teat end disinfection and dry cow therapy. Development of equally effective control methods for the environmental pathogens will be an important area of future mastitis research.

Animal Husbandry↗
PubMed1985

Comparison of electrical conductivity of milk with other indirect methods for detection of subclinical mastitis.

Efficacy of detecting subclinical mastitis by electrical conductivity of milk was compared with that of other indirect methods including chloride, sodium, potassium, lactose, bovine serum albumin, and somatic cell count of milk. Quarter samples of foremilk, strippings, and bucket milk were obtained from 75 cows at the afternoon milking over 8 wk. Infection of quarters was ascertained by bacteriological analysis. Electrical conductivity, chloride, and sodium content of milk were more accurate for predicting infection status of quarters than were other variables. Most variables were more accurate in predicting infection when measures were in strippings rather than in foremilk or bucket milk. For measures in strippings, misclassifications by electrical conductivity were 11.2 and 15.5% for false positives and false negatives. The accuracy of the electrical conductivity of milk for detection of subclinical mastitis compared favorably with all indirect methods. Accuracy of detection and adaptability to both manual and automatic cow-side mastitis detection systems indicate that the method has considerable potential as a screening test for subclinical mastitis.

Animals↗
PubMed1988

Genetic parameters for clinical mastitis, somatic cell counts, and milk production estimated by multiple-trait restricted maximum likelihood.

Heritabilities and genetic correlations for mastitis, SCC, and milk production in first lactation were calculated using data from the Swedish disease recording system. Genetic parameters were estimated from sire components of variance and covariance obtained from a multiple-trait restricted maximum likelihood procedure. Data were stratified into three subsets according to breed and AI stud. The numbers of cows were 46,431, 25,373, and 25,201, respectively. Heritabilities of mastitis and SCC averaged .014 and .080, but breed differences were seen. Genetic correlations between mastitis and SCC were moderately high, averaging .6. Milk production showed a slightly unfavorable genetic correlation with mastitis and SCC.

Animals↗
PubMed1989

Prevention of bovine mastitis by a postmilking teat disinfectant containing chlorous acid and chlorine dioxide in a soluble polymer gel.

A natural exposure study was conducted in a herd of 150 lactating dairy cows for 18 mo to determine the effectiveness of chlorous acid and chlorine dioxide in a soluble polymer gel as a postmilking teat disinfectant for the prevention of bovine mastitis. Right quarters of cows were dipped in the experimental teat dip after milking machine removal. Left quarters were not dipped and served as within-cow negative controls. The experimental teat dip reduced Staphylococcus aureus infections 67.4%, Streptococcus dysgalactiae infections 63.8%, and Streptococcus uberis infections 27.8%. Overall efficacy of the chlorous acid and chlorine dioxide teat dip against major mastitis pathogens was 52.2%. The experimental teat dip reduced Corynebacterium bovis infections and coagulase-negative staphylococcal infections also by 45.8 and 38.7%, respectively. Overall efficacy against minor mastitis pathogens was 43.4%. Under conditions of this trial, the experimental teat dip containing chlorous acid and chlorine dioxide was effective in preventing new intramammary infections against a variety of mastitis pathogens.

Animals↗
PubMed1990

Preinfection functions of blood polymorphonuclear leukocytes and the outcome of experimental Escherichia coli mastitis in the cow.

The relationship between preinfection functions of blood neutrophils and outcome of experimental Escherichia coli mastitis was studied in 11 cows. Random migration, chemotaxis, phagocytosis, and chemiluminescence by neutrophils were determined in white blood cell suspensions, and in purified neutrophil suspensions. The course of E. coli mastitis (10(4) E. coli 0:157 in rear quarters) was monitored using clinical parameters, counts of E. coli in mastitic secretion, and milk production. Regressions were calculated for areas under curves of these parameters and preinfection activities of neutrophils. Chemiluminescence by nonstimulated neutrophils in white blood cell suspensions was negatively correlated with counts of E. coli in secretion and with losses in milk production. The chemotactic differential in white blood cell suspensions minus the chemotactic differential in purified suspensions of neutrophils referred to as delta varied from -.66 to +.50, indicating, respectively, inhibition and stimulation of chemotactic activity of neutrophils in white blood cell suspensions. Delta correlated negatively with counts of E. coli in mastitis secretion, inhibition of the amplitude of rumen contractions, and losses in milk production. We hypothesize that a factor in white blood cell suspensions may be involved in the down-regulation of the migratory response of neutrophils during E. coli mastitis.

Animals↗
PubMed1990

Interaction between the respiratory burst activity of neutrophil leukocytes and experimentally induced Escherichia coli mastitis in cows.

The respiratory burst activity of neutrophil leukocytes from bovine peripheral blood was studied before and during an experimentally induced Escherichia coli mastitis. The competence of neutrophils to generate reactive oxygen species following stimulation with opsonized particles prior to infection was negatively correlated with severity of subsequently induced E. coli mastitis. In the presence of the soluble activator, phorbol myristate acetate, no such correlation was obtained. However, combination of blood neutrophil numbers with phorbol myristate acetate induced respiratory burst competence, called reactive oxygen species-generating capacity, displayed a negative correlation with the intensity of a subsequent inflammation of the bovine mammary gland. At the onset of mastitis, a concomitant reduction in blood neutrophil numbers, a strong shift in cell types, and a substantial decrease in production of reactive oxygen species occurred. Reestablishment and even enhancement of the respiratory burst activity coincided with the reappearance of mature neutrophils. Possible stimulatory effects on neutrophil superoxide generation are discussed. Data suggest that generation of reactive oxygen species by mature neutrophils may be of primary importance for microbial killing during the onset and recovery from mastitis.

Animals↗
PubMed1990

Lymphocyte blastogenesis inhibition by milk whey as an indicator of mastitis.

Sixty milk whey samples prepared from quarters of five cows with a history of mastitis were tested for their ability to inhibit DNA synthesis in mitogen-stimulated lymphocytes. The inhibitory activity was compared with milk SCC, electrical conductivity, pH, and the number of colony-forming bacteria in the milk. Milk whey contained factors that inhibited DNA synthesis in cultured lymphocytes. Inhibition of mitogen-induced DNA synthesis increased with the clinical severity of mastitis and with increased values of indirect indicators of mastitis. The increases in inhibition and electrical conductivity were delayed past the increases in SCC. Milk whey (10 microliters) from quarters with clinical mastitis and from quarters with SCC greater than 900,000 inhibited 96 to 100%, 84 to 100%, and 69 to 100% of DNA synthesis in 3-d cultures of lymphocytes stimulated with Concanavalin A, phytohemagglutinin P, and pokeweed mitogen, respectively. The numbers of colony-forming bacteria correlated least with the inhibitory activity.

Animals↗
PubMed1991

N-acetyl-beta-D-glucosaminidase, etiologic agent, and duration of clinical signs for sequential episodes of chronic clinical mastitis in dairy cows.

This study examined effects of repeated episodes of clinical mastitis in chronically infected quarters on milk N-acetyl-beta-D-glucosaminidase activity and duration of clinical signs. Milk samples were collected at each clinical onset from 49 chronic mastitis cases on a 1700-cow Michigan dairy farm. There were 49 first episodes of clinical mastitis, 49 second episodes, and 13 episodes of third or more. Agents isolated were Staphylococcus aureus (18.4%), Staphylococcus (7.3%), no growth (20.2%), environmental pathogens (streptococci other than agalactiae, Escherichia coli, Klebsiella spp., Enterobacter spp., and Citrobacter spp.) (22.0%), other pathogens (Serratia spp., Bacillus spp., diphtheroids [Corynebacterium spp. and Actinomyces pyogenes], Pseudomonas spp., and Nocardia spp.) (11.9%), mixed pathogens (two agents isolated) (12.8%), and contaminated samples (7.3%). Etiologic agents, duration of clinical signs, and NAGase did not differ by episode number. The correlation between log of NAGase and log of time until clinical recovery was .34. The relationship between NAGase and duration of clinical signs was strongest for second episodes, and weakest for third and greater episodes of chronic mastitis.

Acetylglucosaminidase↗
PubMed1992

High cortisol concentrations and mediation of the hypogalactia during endotoxin-induced mastitis.

A series of experiments was conducted to define the role of cortisol in the hypogalactia during endotoxin-induced mastitis. In the first experiment, three of six nonmastitic cows were given a continuous infusion of trilostane, a 3 beta-hydroxysteroid dehydrogenase inhibitor that blocks enhanced cortisol synthesis. Trilostane had no effect in these cows. In the second experiment, six midlactation cows were given 10 micrograms of endotoxin in each of two homolateral quarters to induce mastitis. Three of these cows also received trilostane. Increased serum cortisol following endotoxin infusion was blocked by trilostane treatment, whereas serum glucose and rectal temperatures were unaffected. Preventing the cortisol increase failed to reduce hypogalactia in endotoxin-infused or uninfused quarters. Decreases in milk production and increases in measures of mammary inflammation were greater in trilostane-treated cows, indicating that endogenous cortisol may moderate the cow's inflammatory response. In the third experiment, three of six nonmastitic cows were injected intramuscularly with 150 IU of ACTH. Serum cortisol concentration exceeded 70 ng/ml for at least 3 h in cows receiving ACTH. This cortisol concentration, comparable with concentrations found during endotoxin mastitis, did not inhibit milk production. Together, these data demonstrate that the acute cortisol increase does not mediate the hypogalactia associated with endotoxin-induced mastitis.

Animals↗
PubMed1993

Prevention of bovine mastitis by a premilking teat disinfectant containing chlorous acid and chlorine dioxide.

The objective of this study was to evaluate the efficacy of a premilking teat disinfectant for the prevention of mastitis in dairy cows under natural exposure conditions. Predipping was compared with a negative control using a split udder experimental design. All teats were dipped after milking with the same teat dip. Percentage of quarters newly infected by major mastitis pathogens was 34% lower in quarters with teats predipped and postdipped than in quarters with teats postdipped only. New IMI by Streptococcus uberis and Staphylococcus aureus were significantly lower in quarters with teats predipped and postdipped than in quarters with teats postdipped only. Differences in incidence of clinical mastitis between treatment groups approached significance. Predipping and postdipping were no more effective against Gram-negative bacteria, coagulase-negative Staphylococcus species, and Corynebacterium bovis than postdipping only. No chapping or irritation of teats was observed, and no adverse effects were noted using the test product as a premilking and postmilking teat disinfectant. Results of this study suggest that predipping and then postdipping with the test product was a more effective procedure against major mastitis pathogens than postdipping only.

Animals↗
PubMed1994

Workshop: genetic improvement of resistance to mastitis of dairy cattle with special emphasis on somatic cell count.

A scientific workshop was held with specific emphasis on genetic improvement of resistance to mastitis based on SCC. The first objective was to present current knowledge of physiological and genetic aspects of resistance to mastitis. The second objective was to provide a forum for discussion of various strategies for genetic improvement of resistance to mastitis with particular emphasis on use of genetic evaluations for SCC. Contributions covered physiological, immunological, and genetic aspects of resistance to mastitis and SCC, as well as developments in genetic evaluation for SCC.

Animal Husbandry↗
PubMed1994

A field trial with an experimental vaccine against Staphylococcus aureus mastitis in cattle. 1. Clinical parameters.

A total of 108 heifers were included in a placebo-controlled multicenter study on the use of an experimental Staphylococcus aureus mastitis vaccine containing whole, inactivated bacteria with pseudocapsule, alpha and beta toxoids, and a mineral oil as adjuvant. The heifers were injected in the area of the supramammary lymph nodes twice before calving and were observed and sampled throughout the first lactation. None of the vaccinated cows suffered from clinical Staph. aureus mastitis, and only 8.6% suffered from subclinical Staph. aureus mastitis, but a total of 16.0% of the control cows suffered from clinical or subclinical Staph. aureus mastitis. Mean SCC in vaccinated and control cows were the same throughout the lactation. Local swellings at the injection site were palpable in a substantial proportion of the vaccinated cows. In the statistical analyses, when cow was used as the unit of concern, no significant differences occurred between groups. However, when all parameters on udder health were considered together, the results indicated a potential protective effect of this vaccine during the entire lactation.

Animals↗
PubMed1995

A knowledge-based system for diagnosis of mastitis problems at the herd level. 2. Machine milking.

A knowledge-based system for the diagnosis of mastitis problems at the herd level must search for possible causes, including malfunctioning milking machines or incorrect milking technique. A knowledge-based system on general mechanisms of mastitis infection, using hierarchical conditional causal models, was extended. Model building entailed extensive cooperation between the knowledge engineer and a domain expert. The extended knowledge-based system contains 12 submodels underlying the overview models. Nine submodels were concerned with mastitis problems arising from machine milking. These models are briefly described. The knowledge-based system has been validated by other experts after which the models were adjusted slightly. The final knowledge-based system was validated to data collected at 17 commercial dairy farms with high SCC in the bulk milk. Reports containing the farm data were accompanied by recommendations made by a dairy farm advisor. This validation showed good agreement between the knowledge-based system and the dairy farm advisors. The described knowledge-based system is a good tool for dairy farm advisors to solve herd mastitis problems caused by a malfunctioning milking machine or incorrect milking technique.

Animals↗
PubMed1995

Financial analysis of alternative treatments for clinical mastitis associated with environmental pathogens.

For two large California dairy herds with twice daily milking, 171 infected quarters of lactating cows with mild clinical mastitis were randomly assigned to one of three treatment groups. Group A (50 cows) was treated with 62.5 mg of intramammary amoxicillin every 12 h for three milkings. Group C (50 cows) was treated with 200 mg of intramammary cephapirin every 12 h for two milkings. Group O (71 cows) was treated with 100 U of intramuscular oxytocin every 12 h for three milkings. Clinical cure rates did not differ among treatment groups. The cost per episode of clinical mastitis was higher ($54.47) for group C than for groups A ($38.53) or O ($34.88). Group O had a higher incidence of relapse (41%), and a greater percentage of group O cows (65%) experienced an additional mastitic event in the enrolled lactation than did cows in groups A and C. Treatment had no effect on the mean number of nonsalable milkings (24.7) associated with mastitis in the lactation interval subsequent to enrollment on the trial. Twenty-two percent of the cows accrued more than 30 nonsalable milkings and produced 55% of the total nonsalable milkings associated with mastitis. There was no treatment effect on total milk production, fat production, or time to removal of the enrolled cows from the herd.

Amoxicillin↗