Disposition kinetics of lactoferrin in milk after intramammary administration

Disposition kinetics of lactoferrin (Lf) purified from cheese whey was studied in the milk of Finnish Ayrshire cows after intramammary administration of 1 g of Lf into one udder quarter. Intramammary administration of 1 g of Lf increased Lf concentration in milk for several hours. Mean elimination half-life of Lf was 2.2 h and a mean maximum concentration of 6.3 g/L was reached between 1 and 4 h. After 8 h of administration, Lf concentrations in milk decreased to almost the same level as before the infusion. Forty-eight hours postinfusion, the mean Lf concentration was again higher than in the milk samples taken before the infusion of Lf, being on average 1.5 g/L. Lactoferrin caused some local tissue irritation in the udder quarter. Severity of the irritation reactions varied between cows. The udder quarters of primiparous cows reacted faster than those of multiparous cows, but irritation reactions decreased more rapidly in the older cows than in primiparous cows. The cows had no general signs such as fever or anorexia. The somatic cell count returned to baseline level 4 days after the administration.     

Interdependence and distribution of subclinical mastitis and intramammary infection among udder quarters in dairy cattle

The objective of the present study was to determine the distribution of subclincial mastitis and intramammary infection (IMI) across udder quarters and to quantify, if any, the level of interdependence between quarters. Subclinical mastitis was defined as an udder quarter somatic cell count of > or =250,000. Intramammary infection was defined as the presence of pathogens in an udder quarter. The data used in the analyses consisted 6577 test-day records from 2034 lactations with observations on subclinical mastitis and 8428 test-day records from 2575 lactations with observations on IMI; each test-day record consisted data on all four udder quarters. Records were from animals on three research herds in southern Ireland. Observed distributions of IMI were compared to expected distributions, estimated using a binomial probability distribution, assuming independence among quarters. Generally, the observed frequencies deviated significantly from the expected frequencies, indicating some level of interdependence between quarters. Intraclass correlations were estimated from a mixed model including cow and test-day record nested within cow as random effects; fixed effects in the model included herd, year of calving, month of calving, parity, days in milk at sampling and interactions. Intraclass correlations within test-day record ranged from 0.14 to 0.50 for subclinical mastitis and from 0.02 to 0.40 for IMI. Thus, substantial interdependence between quarters exists which should be accounted for when analysing data from experiments across udder quarters. Failure to do so may result in incorrect inferences from statistical tests.     

Antibiotic Treatment of Experimental Staphylococcus aureus Infections of the Bovine Mammary Gland

Experimental infections were produced in 78 quarters of 17 cows by the infusion of small numbers of a single strain of Staphylococcus aureus. In each single experiment three quarters in a cow were infected, with the fourth left as a control. At times varying from three to 60 days after the infusion of organisms, a standard intramammary antibiotic treatment was administered on a single occasion. A cure was arbitrarily defined as the absence of the organism in foremilk, from direct plating and replated incubated milk, together with return to normal somatic cell count levels as determined by an electronic counter.

With these standardized conditions the effects of a number of cow associated factors on the outcome of the therapy were determined.

Forty-three of the 78 quarters (55%) were cured by the standard treatment. Significant differences in percentages of quarters cured were found to be associated with the duration of infection before therapy, the lactation age of the cow, the length of time in lactation, somatic cell count in milk at time of treatment, the location of the quarter in the udder and individual cows. No significant effects on the outcome of the standard treatment were found associated with the number of bacteria in the secretion at the time of treatment, previous infection and cure in a quarter nor the season of the year in which treatment was given. Of the 35 quarters in which infection recurred following treatment, organisms were reisolated from 12 within four days, 18 between five and nine days, four between ten and 17 days and one after 28 days.

From these data it is apparent that if, as has been suggested, models such as described are to be used for efficacy trials, standardization of some parameters is essential.

     

Inflammatory reactions in the teat and udder of the dry cow

The inflammatory reactions in the teat and udder of the dry cow were studied by total and differential somatic cell counts (SCC) and by measuring bovine serum albumin, N-acetyl-beta-D-glucosaminidase (NAGase), plasminogen and plasmin. The teat and udder cisterns were surgically separated from each other in two udder quarters of each cow. Salmonella endotoxin was infused in one teat cistern and one udder quarter, and saline was infused in one teat cistern and one udder quarter. The inflammatory response was followed by several samplings post infusion. The reactions in the dry udder quarters were mainly in line with the results of similar studies in lactating glands. The differential SCC and the NAGase results were, however, somewhat different. The teats were capable of a strong inflammatory response. Reactions different from those seen in the glands were observed with regard to permeability changes and NAGase. The experimental model used showed promising results and is suitable for further studies of the inflammatory process.     

Methods of diagnosing subclinical mastitis in dairy cow mastitis control programs

The number of somatic cells and the isolation of the causative agents of mastitis in quarter, composite, bucket, and bulk tank samples of cow's milk was determined four times during a six-month period. The number of somatic cells in milk samples indicated a degree of mastitis infection and was influenced neither by the year season nor by the length of lactation. At a repeated examination of 28 dairy cows an increased number of somatic cells in milk was found once in 68 udder quarters and with three successive samplings only in 21 quarters. The etiological agents of mastitis were detected once in 31 quarters and three times in succession only in five quarters. The number of cows positive by the number of cells in quarter samples of milk increased from 52.9-58.8% at a single examination to as much as 100% at four examinations. The etiological agents of mastitis were isolated in a single examination in 17.6% of cows and at four examinations in 58.8% of cows. The composite and bucket samples of milk containing 200 to 300 thousand cells per ml are recommended to be considered as mastitis-positive: in 68 to 78% they came from cows having more than 500 thousand cells per ml at least in one quarter sample. The number of cells in a bulk sample was in correlation with the percentage of cows having a positive NK-test (similar to CMT) and positive isolation of S. agalactiae from quarter milk samples.(ABSTRACT TRUNCATED AT 250 WORDS)     

重组溶葡萄球菌酶对奶牛乳房炎的疗效研究

以85头患乳房炎奶牛共104个乳区为研究对象,随机分为4组,每组26个,分别用重组溶葡萄球菌酶粉低（200U／乳区）、中（400U／乳区）、高（800U／乳区）三个剂量,对照组为青霉素G钠（160万IU／乳区）,每天早晚挤奶后乳池灌注给药,共4d,研究不同剂量重组溶葡萄球菌酶对奶牛乳房炎的治疗效果。试验结果显示,低、中、高剂量重组溶葡萄球菌酶均能有效清除感染乳区的链球菌、葡萄球菌、化脓隐秘杆菌等G^＋菌,大幅降低牛奶中的白细胞数,提高日产奶量。其中低剂量组对隐性乳房炎、临床型乳房炎的有效率和治愈率略优于青霉素G钠（P〉0．05）;中、高剂量对隐性乳房炎、临床型乳房炎的有效率和治愈率显著优于青霉素G钠（P〈0．05）;中、高剂量的疗效相当（P〉0．05）。重组溶葡萄球菌酶是一种很好的治疗奶牛隐性乳房炎和临床乳房炎备选药物。     

Staphylococcus aureus exosecretions and bovine mastitis

The role of Staphylococcus aureus and coagulase-negative staphylococcal exosecretions in bovine udder infection was tested by monitoring the cows' response to in vivo inoculation of bacterial exosecretions into udder quarters. Twenty Israeli-Holstein dairy cows were included in the study; two or three of the udder quarters of each cow were intracisternally inoculated with 0.04-0.05 mg/quarter (total proteins) of the various sterile bacterial exosecretions in a sterile pyrogen-free saline. Each udder was inoculated with two or three different bacterial exosecretions or placebo (Columbia Broth). Cows were monitored for 96 h post-inoculation for rectal temperature, heart and respiratory rates, alimentary tract activity (rumen contraction), udder temperature, pain, oedema and udder size. Milk samples were examined bacteriologically and for somatic cell count, N-acetyl-D-glucosaminidase (NAGase) activity and somatic cell differentiation. No enterotoxins (beta-G) or toxic shock syndrome toxin-1 were detected in response to any of the bacteria tested. Control quarters or those inoculated with Columbia Broth, showed similar NAGase and somatic cell count values throughout the experiment. Twelve of the 18 strains tested, induced inflammation in the inoculated quarters while six did not. Of the 12 strains causing local inflammation, only six were found significantly different from the control and were considered as high response (group 1). The other six that caused a local inflammation did not differ significantly from the control, and were considered to be moderate response (group 2). The six S. aureus isolates that did not cause an inflammatory response were considered to have low response (group 3). In all quarters inoculated with S. aureus bacterial exosecretions belonging to groups 1 and 2, the polymorphonuclear cells and macrophages were proportionally increased while CD4+ and CD8+ T-lymphocyte populations decreased. One-dimensional NuPAGE (7%) Tris-acetate gel electrophoresisof the bacterial exosecretions revealed four different bands appearing between 36 and 31 kDa, marked from top to bottom as A, B, C and D. An association was found between the combinations of expressed bands and the cow responses: the majority of the cases could be linked to the expression of bands B and C.     

Quarter Milking for Improved Detection of Increased SCC

The aim of the present study was to investigate whether milk composition and milk yield are changed in relation to a moderate increase in milk somatic cell count (SCC) in separate udder quarters. During a period of 13 weeks, 4158 bulk quarter milk samples from 68 cows were collected and analysed for milk SCC and milk composition. The sampling was done twice weekly. The cows were in different stages of lactation and in different lactation numbers. For calculations, three groups of cows were formed according to their SCC value. Group 1 cows, where all quarters had an SCC <100,000 cells/ml at all sampling occasions, were considered to be non-affected. Group 2 cows had one udder quarter with an increased SCC >100,000 cells/ml and 1.5-fold higher than the opposite quarter at one sampling occasion. For group 3 cows, the increase in SCC remained for several consecutive sampling occasions. Data from group 1 cows revealed that front and rear quarters were similar when compared with each other. For group 3 cows, the lactose content in milk decreased significantly, simultaneously with the increase in SCC and remained decreased for two sampling occasions after the initial increase in SCC. It was concluded that deviations in lactose content within front and rear quarters, respectively, may be a useful tool for detection of moderately increased SCC in separate udder quarters.     

Physiological and morphological changes in bovine mammary glands following intramammary infusion of recombinant interferon-gamma.

Eleven lactating dairy cows were used to evaluate the response of bovine mammary glands to increasing doses of recombinant bovine interferon (rBoIFN)-gamma. Right front and rear quarters were intramammarily infused with eight different doses (10(2) U to 2 x 10(8) U/quarter) of rBoIFN-gamma; each dose was tested in at least two quarters. Left udder halves served as within animal controls in which quarters were injected with a saline placebo or were not infused at all. Milk secretion samples for compositional analysis were collected from each quarter prior to infusion and at 6, 24, 36 and 48 h following infusion. Animals were slaughtered immediately following the 48 h sampling period and mammary tissue was obtained for morphometric analyses. Milk composition was similar between control quarters and those quarters infused with up to 10(5) U of rBo-IFN-gamma during the entire sampling period. Quarters infused with 10(6) U and 10(7) U of rBoIFN-gamma had higher milk somatic cell counts (SCC) following treatment compared with preinfusion values. Changes in the composition of mammary secretion were most dramatic in quarters infused with greater than or equal to 10(8) U of rBoIFN-gamma as indicated by the significant increase in SCC and milk pH with a concomitant decrease in lactose concentration when compared with pre-infusion values or with control quarters. Morphometric analysis of tissue demonstrated an increase in stroma, a decrease in luminal area, and a marked increase in the number of infiltrating leukocytes in those quarters infused with the higher doses of rBoIFN-gamma.(ABSTRACT TRUNCATED AT 250 WORDS)     

Effect of teat dipping with a germicide barrier teat dip in late gestation on intramammary infection and clinical mastitis during the first 5 days post-partum in primiparous cows

The effect of teat dipping with a barrier teat dip prior to parturition on intramammary infection (IMI) and clinical mastitis during the first 5 days post-partum was investigated in a split udder trial in 149 Holstein-Frisian heifers. Their left front and right hind quarters were dipped three times weekly (i.e. Monday, Wednesday and Friday) with a barrier teat dip containing 0.1% polyvidon iodine from day 260 of gestation until parturition. The opposite quarters (right front and left hind quarter) served as untreated control. Bacteria were isolated from 52.2% of quarter milk samples collected immediately after parturition prior to first machine milking. Staphylococcus aureus and coagulase-negative staphylococci (CNS) were predominantly found in the samples (29.2 and 35.6% of the positive samples, respectively). At parturition 6.7% of the heifers showed signs of clinical mastitis and another 27.5% developed signs of clinical mastitis during the first five days of lactation. No significant differences were found between treated and control quarters regarding IMI and incidence of clinical mastitis. Teat dipping prior to parturition in primigravid dairy heifers did not improve udder health in this trial.     

The incidence of mastitis treated with antibiotics in large-scale Hungarian Holstein-Friesian dairy farms

Treated mastitis episodes at large Hungarian dairy farms were studied to determine the distribution of mastitis treated with antibiotics among quarters of the udder. Data were detailed records of all mastitis episodes that occurred during 1976 lactations in Farm A infected with Staphylococcus aureus (from May 1995 through July 1998) and 808 lactations in Farm B free from S. aureus (from January 1999 through March 2001). The distribution of treated quarters was compared with mathematical expectations based upon a random distribution in the case of Farm A. Results on mastitis incidences for different lactation stage groups showed an increasing incidence within subsequent lactation stage groups in Farm A. In contrast, in Farm B the mastitis incidence for lactation stage group between 35 and 100 days was the highest, but beyond 100 days the incidence decreased and reached the lowest value. Results gave strong evidence that the four quarters within the udder are not distributed randomly with respect to naturally occurring episodes of treated mastitis. More episodes than expected occurred in which only one or all four quarters were treated. Fewer episodes than expected with two or three treated quarters were observed. In both farms, the mastitis rate for rear quarters was higher than for front quarters, and the incidence of right quarter mastitis episodes was higher than that of left quarter mastitis episodes.     

The Use of Induced Mammary Infections for Evaluating Dry Cow Treatment Products II. Trial of a Proposed Method to Compare Three Levels of Novobiocin

Infections were induced at the end of lactation in all udder quarters of 19 cows by the infusion of 0.2 mL of a 10^-4 dilution in milk of a six hour milk culture of Staphylococcus aureus, strain 305 (A.T.C.C No. 29740). Two right or two left udder quarters were infected at 15 days and the opposite two five days before the last milking of lactation. Following the last milking all four udder quarters of eight cows were treated with 400 mg novobiocin in 10 mL of 2% aluminum monosterate in peanut oil, gelled. All udder quarters of eight other cows were treated with 50 mg novobiocin in the same vehicle and the udder quarters of three cows were treated with the vehicle only.

At calving, eight of 32 quarters treated with 400 mg novobiocin were still infected, as were 18 of 32 treated with 50 mg of novobiocin and all those quarters treated with vehicle only. Results were identical from udder quarters infected 15 and five days before drying off.

No significant differences were found between quarters in milk yield on the last day of lactation, nor the length of the dry period. An increasing number of udder quarters were infected at calving with increase in lactation age of the cow, although the small number of cows would not allow a firm conclusion. A significant difference in results was found between front and hind udder quarters, only five of 32 front quarters were infected at calving as compared to 21 to 32 hind quarters.

The method proposed was found to give essentially the same results as those from a large field trial using the same antibiotic. It should therefore be useful in evaluation trials of new antibiotic products for dry cow treatment.

     

Field trials on the prophylaxis of intramammary infections in pregnant heifers

The study was carried out in 5 farms on 174 pregnant heifers. Clinical examination of the udder and bacteriological tests of quarter secretion were performed between the 8th and 3rd week before parturition, and then the animals were divided into a control group (64 heifers) and 3 experimental groups and immediately treated. A group of 32 experimental heifers was injected once with antioxidants (Vitamin A--600,000 i.u.; Vitamin D3--200,000 i.u.; Vitamin E--1.5 mg/kg b.w., Selenium--0.022 mg/kg b.w., i.m.). The next group (26 heads) was intramammary infused with antibiotic DC product (cloxacillin). Heifers from last experimental group (52) were injected with lysosyme dimer in a single dose of 0.02 mg/kg b.w. Clinical and bacteriological examinations were made during the first week after calving. The presence of bacteria was found in secretion of 22.6-38.9% udder quarters in 56.2-71.2% of pregnant heifers. The number of infected quarters (cows) did not change distinctly in the first week after calving except the lysozyme dimer group, where a decrease by 30% was noted. The percentage of quarters with elevated somatic cell count was higher in antibiotic DC group and closely similar in the other groups. None of examined methods showed an acceptable prophylactic effect. Clinical mastitis cases during first week after parturition were mostly caused by Escherichia coli, Staph. chromogenes, Staph. simulans, Staph. aureus, Staph. hyicus, Str. uberis, Str. acidominimus and Enterococcus faecalis.     

Udder health implications of premature bovine mammary regression. II. Collateral intramammary reactions in quarters milked normally during 168-hour milk stasis in opposite quarters

This investigation has shown that collateral intramammary reactions (CIR's) occur when secretory disturbances in one quarter lead to corresponding changes in one or more of the other, unperturbed, quarters of the same udder. Compared with normal baseline values, the mean values and variations of bovine serum albumin (BSA), beta-N-acetyl-D-glucosaminidase (NAG), mannose (MAN), galactose (GAL) and glucose (GLU) showed slight increases under CIR conditions. Fluctuations of the carbohydrates preceded changes of somatic cell counts (SCC), BSA and NAG in milk. SCC and NAG showed significant negative correlations with MAN, GAL and GLU, the latter being the only parameter significantly correlated with each of the other parameters. The data suggest that the cow's stress control system responded to the milk stasis in the unmilked quarters, by initiating a form of general stress that affected the whole udder. This aggravated regressive conditions in the unmilked quarters and provoked CIR's in the normally-milked quarters. The CIR's amounted to a transient, regressive, compensatory re-adjustment of lactational homeostasis under conditions of acute general stress. CIR's similar to those investigated could also occur in close association with other local and general stressful conditions, disturb the natural defence of the udder and account for fluctuating mammary resistance to bacterial infection.     

A small episode of single quarter conform infections in lactating dairy cows kept at pasture

For a period of 150 days, an Escherichia co/; infection in a single quarter of the udder of 13 cows occurred on average every 9 days, in a herd of 120 cows kept at pasture under temperate environmental conditions. Most cases were clinically mild, affecting cows in lactations 1 to 10 and at all stages of lactation; none were evident at calving. Samples of secretion from infected quarters sometimes had few demonstrable organisms. Eleven different serotypes in 8 (0) groups were recovered; one isolate was multiply resistant to antibiotics and one infection persisted for 120 days. A precise explanation for this episodic exacerbation of the new infection rate was not established, but probable contributing factors were recognised.     

An intramammary implant in the prevention of infectious mastitis in cows

A sterile polyethylene device was introduced in the milk cistern of two mammary quarters of forty dairy cows. The cows were divided into three groups according to the length of exposure of the device in the cistern (3 days, 14 days, 365 days). The somatic cell counts were studied for a year in the first 10 ml fraction of milk and an increase in the somatic cell counts was found in the quarters having the intramammary device, as compared with the control quarters (having no devices). This difference was marked during lactation and prior to the onset of drying off. For the reduction in the frequency of occurrence of new natural intramammary infections, the activity of the device against S. aureus was limited and no activity against S. agalactiae was proved. The proportions of polymorphonuclears, round-cell elements and macrophages were histologically studied and compared for the udder quarters with and without the intramammary body in correlation with the time of exposure of the device to the milk cistern milieu. The most marked differences in favour of the udder quarters with the intramammary device were recorded in the alveoli containing more cells with a significant proportion of polymorphonuclear leucocytes. Small differences were found in the interstitial and subepithelial zone of the milk cistern. The activity of acid and alkaline phosphatase and adenosine triphosphatase was histochemically determined in the tissue structures of the udder and was found not to change under the influence of the device. Leucocytes and macrophages adhering to the surface of the body were observed under scanning electron microscope.     

The contribution of mammary infections by coagulase-negative staphylococci to the herd bulk milk somatic cell count

Quarter foremilk samples were taken at 2–3 weekly intervals for several years in a experimental herd comprising about 45 cows. The samples were submitted to bacteriological analysis and somatic cell counting. The most prevalent quarter infections from 1982 to 1988 were by coagulase-negative staphylococci (15–20% of all the quarters sampled). Most of these (75.6%) persisted until drying-off Dry cow therapy eliminated 86.5% of these infections. Comparison of udder quarters within cows, involving 775 samples from pairs of non-infected quarters and quarters infected by coagulase-negative staphylococci, yielded geometric means of somatic cell counts of 210 000 and 420 000 cells/ml, respectively. The correlation (r=0.87) between the herd bulk milk somatic cell count (SCC) and its estimation from the quarter milk somatic cell count performed on the same day allowed us to evaluate the contribution of the different categories of quarters, according to their infection status, to the herd bulk milk SCC. Quarters infected by a major pathogen (8.5% of samples) gave rise to 46.6% of the total number of cells, while quarters infected by coagulase-negative staphylococci (17.8% of samples) gave rise to 18.1%. Although coagulase-negative staphylococci represented only a secondary source of somatic cells as compared to major pathogens, they were not a negligible source considering the threshold of 300 000 somatic cells advocated for herd milk of good quality.     

Udder health in beef cows and its association with calf growth

Background

Studies outside the Nordic countries have indicated that subclinical mastitis (measured by milk somatic cell count or the California Mastitis Test), intramammary infections (IMI), or blind quarters in beef cows may have negative effects on beef calf growth. Knowledge on prevalence of such udder health problems in Swedish beef cows is scarce. Therefore, the main aim of this study was to investigate subclinical mastitis, IMI and udder conformation in a number of beef cow herds. Production of β-lactamase in staphylococci was also investigated. Associations between certain cow factors and subclinical mastitis and IMI, and associations between cow and calf factors and 200 day calf weaning weight were also studied. The herds were visited once within a month after calving and once at weaning. Udder examination and quarter milk sampling, for somatic cell count and bacteriology, were performed in 8 to 12 cows per herd and occasion.

Results

Approximately 50%, 40% and 10% of the cows had subclinical mastitis, IMI, and at least one blind quarter, respectively, but the prevalence varied markedly between herds. Intramammary infections (mainly due to staphylococci) were identified in 13-16% of the milk samples. Less than 5% of the staphylococcal isolates produced β-lactamase. Approximately 11% of the cows sampled twice had the same IMI (mostly Staphylococcus aureus) at both samplings. Cow factors of importance for subclinical mastitis and/or IMI were teat and udder shape, breed, parity, presence of blind quarters, and cow hygiene. No significant associations were found between udder health parameters studied and calf weaning weights.

Conclusions

Subclinical mastitis and IMI, but not blind quarters, were common in beef cows, but the prevalence varied markedly between herds. Most IMI were caused by staphylococci and more than 95% of those were sensitive to penicillin. Cows with large funnel-shaped teats or pendulous udder after calving, and cows with blind quarters were at risk of having subclinical mastitis and/or IMI. Poor hygiene was also a risk factor for udder health problems. No significant associations were found between udder health and calf weaning weight. More studies on risk factors are warranted to improve advisory services on awareness and prevention of mastitis in beef cows.     

Effect of intramammary devices on the outcome of induced Escherichia coli infection of bovine mammary quarters

Eighteen Holstein cows, free of intramammary infection, were fitted with smooth (n = 9) or abraded (n = 9) intramammary devices (IMD) in 2 diagonally opposed quarters within 4 weeks after calving. The 2 other quarters of each cow were used as controls. Three to 6 weeks after IMD insertion, depending on when milk somatic cell counts returned to a base-line value of less than 4 X 10(5)/ml, all cows were subjected to bacterial challenge exposure in the front or rear quarters by intracisternal injection of about 30 colony-forming units of Escherichia coli/quarter. Challenge exposure was done immediately after milking. Three weeks after the initial bacterial exposure, the other quarter pairs were similarly challenge exposed. Quarter bacteriologic status, concentration of milk somatic cells, and clinical observations (rectal temperature, milk appearance, udder palpation, and general condition of the cow) were monitored. Infection developed in 14 of 16 (88%) quarters with smooth IMD vs 16 of 16 (100%) control quarters and in 7 of 17 (41%) quarters with abraded IMD vs 17 of 17 (100%) control quarters. The difference in infection frequency between quarters with smooth IMD and quarters with abraded IMD was significant (P less than 0.05). Protection against establishment of infection was associated with somatic cell counts greater than 8.0 X 10(5)/ml in milk collected immediately after milking (7 of 12 quarters) or 4 hours later (11 of 12 quarters). In 10 quarters (59%) of cows fitted with abraded IMD, secretory abnormalities appeared before bacterial challenge inoculation. Abnormal milk or visible blood was observed over periods varying from 2 weeks after insertion through the entire lactation.     

Nocardia mastitis in cattle. 1. Clinical observations and diagnosis in 7 particular cases

Lately reports of nocardial mastitis have been increasing. Therefore the clinical aspects of 7 individual cases were investigated. Pathologic-anatomical changes of the udder were registered and bacteriological examination of tissue and milk probes were performed. All of the cows had a mastitis during previous lactation periods which had to be treated with antibiotics. The infected quarters recovered in no cases. Shortly after parturition 6 cows had a severe acute mastitis. The cows were treated intramammarily and parenterally with various antibiotics during several days. The infected quarter became indurated and strongly enlarged. These changes were not influenced by therapy, and the cows lost weight. 14 days after the outbreak of the illness, all 6 cows were culled. One cow had a chronic Nocardia mastitis with involution of the affected quarter. Though treated several times, this cow did not recover either. The histopathological examination of the affected quarters revealed an acute to chronic, necrotic to granulomatous mastitis. Nocardia asteroides was histologically and bacteriologically proven to be the causative agent. The reason for the frequent infections with Nocardia and the way of infection is not clear yet. Therapy with antibiotics brought no recovery in any cases. The infected cows should be removed from the herd or culled.