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1.
Ewes treated by intramammary infusion of cephapirin benzathine at the end of lactation were less likely to develop new intramammary infections by early in the next lactation. A controlled clinical trial involving 135 treated ewes and 145 untreated control ewes evaluated the prophylactic and treatment efficacy of intramammary antibiotic treatment of ewes at the time of weaning lambs. Milk samples for bacteriologic examination and identification of intramammary infections were collected at weaning of lambs and 1 to 3 weeks into the subsequent lactation. Untreated ewes were 2.6 times more likely than treated ewes to develop new intramammary infections between sampling times. Existence of an intramammary infection in one mammary gland significantly increased the risk of the other mammary gland becoming infected. Treatment also appeared to be associated with a higher cure rate of existing infections.  相似文献   

2.
The nonlactating mammary gland was experimentally inoculated with Escherichia coli. During the first half of the nonlactating period, 32% of 34 inoculated glands were temporarily infected. All intramammary infections were eradicated by the cow without therapy and no signs of mastitis were observed. During the 30 days before parturition occurred, 88% of 42 inoculated glands in the cows became infected. Twenty-three intramammary infections were eradicated by the cow and infection in 14 glands persisted after parturition occurred. Peracute toxic mastitis occurred in those cows with infected glands.  相似文献   

3.
Detection of ovine intramammary infection with the California mastitis test   总被引：1，自引：0，他引：1  
The overall sensitivity of the California mastitis test (CMT) for detecting intramammary infection (the likelihood of a positive CMT score in the presence of intramammary infection) was 69.3%. The specificity of the CMT (likelihood of a negative test in the absence of intramammary infection) was 76.5%. When only infections by major ovine mastitis pathogens were considered, the sensitivity increased to 100% and the specificity decreased to 71.1%. Bacterial cultural examination and CMT scores were recorded for 526 samples of milk obtained from 106 brood ewes. Positive CMT scores were recorded for all samples from udder halves infected with major ovine mastitis pathogens (coagulase-positive staphylococci, Escherichia coli, and Pasteurella haemolytica). The CMT scores for samples from udder halves infected with coagulase-negative staphylococci were variable.  相似文献   

4.
Streptococcus uberis is an important cause of mastitis in dairy cows throughout the world, particularly during the dry period, around the time of calving, and during early lactation. Strategies for controlling S. uberis mastitis have not received adequate research attention and are therefore poorly defined and inadequate. Objectives of the present study were to evaluate the efficacy of extended therapy regimens with pirlimycin for treatment of experimentally induced S. uberis intramammary infections in lactating dairy cows during early lactation and to evaluate the usefulness of the S. uberis experimental infection model for evaluating antimicrobial efficacy in dairy cows. The efficacy of extended pirlimycin intramammary therapy regimens was investigated in 103 mammary glands of 68 dairy cows that became infected following experimental challenge with S. uberis during early lactation. Cows infected with S. uberis in one or both experimentally challenged mammary glands were randomly allocated to three groups, representing three different treatment regimens with pirlimycin, including 2-day (n = 21 cows, 31 mammary quarters), 5-day (n = 21 cows, 32 quarters), and 8-day (n = 26 cows, 40 quarters). For all groups, pirlimycin was administered at a rate of 50 mg of pirlimycin hydrochloride via intramammary infusion. A cure was defined as an experimentally infected mammary gland that was treated with pirlimycin and was bacteriologically negative for the presence of S. uberis at 7, 14, 21, and 28 days after treatment. Experimental S. uberis intramammary infections were eliminated in 58.1% of the infected quarters treated with the pirlimycin 2-day regimen, 68.8% for the 5-day regimen, and 80.0% for the 8-day regimen. Significant differences (P <.05) in efficacy were observed between the 2-day and 8-day treatment regimens. The number of somatic cells in milk decreased significantly following therapy in quarters for which treatment was successful in eliminating S. uberis. However, there was no evidence to suggest that extended therapy with pirlimycin resulted in a greater reduction in somatic cell counts in milk than the 2-day treatment. The S. uberis experimental infection model was a rapid and effective means of evaluating antimicrobial efficacy during early lactation at a time when mammary glands are highly susceptible to S. uberis intramammary infection.  相似文献   

5.
Locally immunising the non-lactating ovine mammary gland by infusing killed Staphylococcus aureus enhances neutrophil accumulation in mammary secretion during subsequent staphylococcal infection. Immunological factors influencing this increased neutrophil response were studied in the present experiments. Glands locally immunised with killed Brucella abortus supported a greater neutrophil response to staphylococcal infection than did glands immunised with killed S. aureus. An enhanced neutrophil response to staphylococcal infection was recorded in 3 of 7 ewes locally immunised with zymosan. Passive immunisation by intramammary infusion of secretions from immunised glands conferred an enhanced neutrophil response during staphylococcal infection. Absence of haemolytic complement in secretions of immunised glands suggested complement was not implicated in the response. Secretions of immunised glands contained elevated concentrations of mononuclear cells. When exudates rich in mononuclear cells were established by infusion of endotoxin into non-immunised glands there was no increase in the neutrophil response to subsequent staphylococcal infection. However, when the mononuclear cell concentration was elevated by intramammary infusion of staphylococcal antigens in systemically immunised ewes there was an increase in the neutrophil response to subsequent infection. Thus humoral and cellular characteristics of the locally immunised mammary gland influence the kinetics of the neutrophil influx during staphylococcal infection.  相似文献   

6.
A field investigation of subclinical mastitis in sheep in southern England   总被引：3，自引：0，他引：3  
The prevalence, aetiology and epidemiological features of subclinical mastitis were investigated in 358 lowland ewes in seven flocks in southern England. Milk samples (2092) were collected at 3-weekly intervals; those which were both bacteriologically and Whiteside test positive were deemed to have originated from glands with subclinical mastitis. The period prevalence of subclinical mastitis was 11.7% and the prevalence remained relatively constant over the course of lactation (5.5-7.0%). The predominant bacterial isolates from 48 glands with subclinical mastitis were streptococci (42%), coagulase-negative staphylococci (33%), Pasteurella haemolytica (17%) and Staphylococcus aureus (8%). Coagulase-negative staphylococci were the predominant isolates (53%) from samples which did not show a positive Whiteside test result. The prevalence of subclinical mastitis increased with age of ewe but was not influenced by the presence of teat lesions. There was a significant association between the development of clinical mastitis (26 glands) and antecedent subclinical mastitis caused by the same organism (10 glands).  相似文献   

7.
The dairy herd at Washington State University had an outbreak of mastitis caused by a single strain of Staphylococcus aureus. The outbreak strain, termed novel, could not be controlled with routine contagious mastitis pathogen control procedures (incidence, 3.4 infections/100 cow months; peak prevalence > 22%). Our objective was to implement mastitis control measures that would decrease the incidence and prevalence of intramammary infection (IMI) caused by S aureus in the herd. The following intervention strategies were successfully implemented: strict segregation of cattle with IMI caused by S aureus, intensified culling of cattle with multiple-quarter IMI caused by S aureus, and inducing cessation of lactation of infected quarters in single-mammary-quarter infected cattle. One year after implementation of these control measures, incidence of IMI caused by S aureus was 0.35 infections/100 cow months, and prevalence had decreased from 20 to 8%.  相似文献   

8.
Patterns of nonclinical intramammary infection in a ewe flock   总被引：1，自引：0，他引：1  
Coagulase-negative staphylococci were the most frequent bacterial isolates from nonclinical intramammary infections (NIMI) in a ewe flock. The prevalence of NIMI was 22.9% of the udder halves at lambing and decreased to 12.5% or less between week 2 and week 6 of lactation. The decrease was due mainly to the elimination of infections involving coagulase-negative staphylococci. The frequency of new NIMI in the first 6 weeks of lactation was less than 1% of the noninfected udder halves per week. The prevalence of NIMI increased steadily from 16.1% of the udder halves at the time of weaning the lambs to 29% at postweaning week 3. The new infection rate averaged 9.7% per week during the postweaning 3 weeks. The principal bacterial isolate in the new NIMI was coagulase-negative staphylococcus. Nonclinical intramammary infection in a ewe flock was monitored by bacteriologic cultural examinations of milk samples obtained from both udder halves of 24 ewes during early lactation and of 31 ewes in the same flock during the early postweaning period. The patterns of NIMI were similar to the patterns reported in cattle.  相似文献   

9.
A survey carried out to determine the prevalence of visible Surcocystis spp. infection in 100 slaughtered cattle in a South Island abattoir revealed 64% infected. Although all ages, genders, breeds and export grades were infected, only host age had a statistically significant effect on the infection rate. Infections were most common in the rectus abdominis and the psoas muscles (47% and 41% respectively). Most infections were light, with less than ten macrocysts seen, though infections of more than 50 macrocysts occurred. The average macrocyst length was 4.WO.10 mm (SE) (n = 233), the average cyst wall thickness 5.3 +/- 0.2 microm (SE) (n = 45). It is thought that the actual prevalence of infection is higher than that recorded and reasons for this are discussed.  相似文献   

10.
The interactions between leukocytes and cytokines during the acute response to intramammary infections in the dry mammary gland of sheep were studied. Dry ewes were experimentally infected in one udder half with either Staphylococcus aureus or Escherichia coli, or infused with saline as control. Udder secretion samples, blood samples and udder tissue samples were collected before and 4, 8 and 24 h after infections/infusions. Total and differential leukocyte counts were calculated in both blood and mammary secretions, and flow cytometry was used to detect the presence of CD4+, CD8+, WC1+, IL-2R+, CD18+ or L-selectin + lymphocytes, CD18+ or L-selectin + neutrophils, and CD14+ leukocytes. Moreover, the concentrations of interleukin-1 beta (IL-1 beta), interleukin-8 (IL-8) and granulocyte-macrophage colony stimulating factor (GM-CSF) in udder secretions were measured using ELISA, and RT-PCR was used to detect the presence of corresponding cytokine mRNA in udder tissue biopsies. The results suggest an association between the concentrations of IL-1 beta, IL-8 and the intensity of neutrophil infiltration of the infected gland. Immunologically relevant changes in proportions of lymphocyte subpopulations might also occur in the acute phase of the inflammatory reaction of the udder. Greater cellular and cytokine responses to E. coli infection may have contributed to the milder clinical picture and more rapid resolution of infection than that seen for S. aureus. Enhancing the production of pro-inflammatory cytokines may improve defence against bacterial mastitis.  相似文献   

11.
A bacteriological survey for the study of non-clinical intramammary infection in the sheep udder was carried out in 88 Assaf ewes. A mean infection prevalence in the first few weeks of lactation was 55%. The most common bacterial isolates were Micrococcus spp. followed by coagulase negative staphylococcus, together accounting for 93% of the total number of isolates. An infection prevalence of 54% was found in ewelambs 2 days after their first lambing, indicating a marked new infection rate around lambing. Generally, the course of lactation was characterized by dynamic changes of new infection and spontaneous resolution. About 5% of half udders examined developed clinical mastitis. The comparison of bacteriological data from mastitic milk samples and from samples taken from the same half udders before the appearance of the clinical disease could not support the theory that in sheep, mastitis is a clinical exacerbation of a non-clinical intramammary infection.  相似文献   

12.
A survey carried out to determine the prevalence of visible Sarcocystis spp. infection in 100 slaughtered cattle in a South Island abattoir revealed 64% infected. Although all ages, genders, breeds and export grades were infected, only host age had a statistically significant effect on the infection rate.

Infections were most common in the rectus abdominis and the psoas muscles (47% and 41% respectively). Most infections were light, with less than ten macrocysts seen, though infections of more than 50 macrocysts occurred.

The average macrocyst length was 4.1±0.10 mm (SE) (n = 233), the average cyst wall thickness 5.3 ±0,12 μm (SE) (n = 45).

It is thought that the actual prevalence of infection is higher than that recorded and reasons for this are discussed.  相似文献   

13.
The prevalence of Chlamydia pecorum and Chlamydia pneumoniae infections in two free-range koala populations was assessed using genus-specific PCR combined with species-specific DNA probe hybridisation. Population A had a very high overall level of chlamydial infection (85%) with significantly more of these infections being due to C. pecorum (73%) compared to C. pneumoniae (24%). The second population had a much lower prevalence of infection (10%) with equal levels of both species. An important finding of this study was that. while five of 24 C. pecorum-infected koalas had clinical signs of the disease (both ocular and urogenital sites), none out of seven C. pneumoniae-infected koalas had signs of clinical disease. This suggests that C. pecorum may be the more pathogenic of the two chlamydial species infecting this host. The level of infection (assessed by intensity of the specific hybridisation signal) also differed between chlamydial species, with C. pecorum infections ranging from low to high grade whereas C. pneumoniae infections were always low grade. When the age of infected koalas was examined, 58% of young, sexually immature koalas were found to have C. pecorum infections, increasing to 100% of koalas in the older age groups. This suggests that, in this population at least, young koalas are readily infected with C. pecorum from their mothers. While the infection levels with C. pneumoniae were too low to be statistically significant, again, sexually immature koalas were found to be infected. The recent separation of chlamydial infections in koalas into two species is beginning to indicate different epizootiologies for koala C. pecorum compared to koala C. pneumoniae.  相似文献   

14.
Epidemiology of Haemophilus somnus in young rams   总被引：1，自引：1，他引：0       下载免费PDF全文
The prevalence of Haemophilus somnus in the prepuce of young rams was examined. Of 473 rams entering Record of Performance (ROP) stations at 50 days of age, 43 (9.1%) were positive. Average daily gain was not affected by Haemophilus status, but was influenced by breed of ram. Suffolks were predicted to gain 0.515 kg daily compared to 0.427 kg for a group combining all other breeds. Using logistic regression to identify risk factors for individual H. somnus infection, rams in 1989 were 0.382 times as likely to be infected as rams in 1988, and Suffolks were 0.314 times as likely to be infected as the other breeds group, but these factors were not significant at the flock level. Of 80 eligible flocks of origin, 22 (27.5%) were classified as infected with H. somnus, based on rams submitted to the ROP station. Infected flocks contributed 133 rams, 43 (32.3%) of which were positive. There was no association between H. somnus status and lambing percent of the percent of abortions and stillbirths, but there was a statistically significant association with the percent of ewes which failed to lamb. In the model developed, 6% of the bred ewes in noninfected flocks failed to lamb, compared to a rate of 12% in infected flocks. These results suggest H. somnus may influence ewe fertility earlier, rather than later in gestation. Purchasing replacement animals and having cattle on the farm were risk factors for Haemophilus infection in the flock. Where replacements had been purchased within the previous year, the risk of flock infection rose 8.5 times, and on farms having cattle as well as sheep, the risk rose 13.2 times.(ABSTRACT TRUNCATED AT 250 WORDS)  相似文献   

15.
From 1985 to 1989 lambs persistently infected with border disease virus (BDV) were produced for comparative immunological studies by infecting 57 susceptible pregnant ewes between 50 and 60 days' gestation with Moredun or Oban strains of BDV. Ewes were infected either by injection with virus grown in cell culture or by housing with lambs excreting BDV. There was no significant difference in the outcomes of these different methods of infection. There was a significant difference in the number of viable lambs born to ewes receiving the two viruses. Of 41 ewes infected with Moredun virus 21 produced 32 live lambs of which 17 were reared to 1 month old (53% viability). Of 16 ewes receiving Oban virus 10 gave birth to 17 live lambs of which 15 were reared to 1 month old (88% viability). All the lambs born to ewes infected with Moredun BDV had varying signs of tremor and increased hairiness ("hairy-shakers") while those born to ewes infected with the Oban virus had no obvious clinical signs. Survival of the lambs was poor. Up until February 1991, 14 Moredun and 10 Oban sheep between the ages of 4 months and 5.5 yr had died from a variety of causes. The two commonest causes were a chronic wasting syndrome and a mucosal disease-like syndrome which was associated with the recovery of cytopathic BDV. Mating of unrelated persistently infected sheep was largely unproductive although 2 lambs were reared.  相似文献   

16.
The clinical, haematological and functional changes which followed three consecutive intramammary infections of Streptococcus agalactiae in the first lactation of eight heifers, four of which were systemically hyperimmune to the organism, are described. Irrespective of whether it was a vaccinated or non-vaccinated heifer or first, second or third infection the clinical features during the first 24 hours were characterised by elevated temperatures with hard, swollen and painful infected quarters. First infections were almost all of short duration because of self cure, while second or third infections were prolonged, with intermittent excretion of bacteria and low cell counts. Milk yields of infected quarters were depressed, ranging from 8 per cent in short infections to 31 per cent in chronic infections. All blood parameters remained within normal limits with the exception of total and differential white cell counts, which showed a change from a quantitative to a qualitative response by the third infection. The most significant finding was the absence of any real difference between the systemically hyperimmune and the non-vaccinated heifers, suggesting that circulating antibody has little effect against intramammary infection.  相似文献   

17.
OBJECTIVE: To investigate intrauterine infection of foetuses with Mycobacterium avium subsp paratuberculosis and the presence of infection in mammary secretions of sheep. DESIGN: A study of 142 late-pregnant ewes and their foetuses from two heavily infected flocks. PROCEDURE: Infection of ewes was determined at necropsy by histopathology and culture of tissues and mammary secretions. Antemortem tests (clinical assessment, faecal culture and serology) were also applied. Foetuses from 59 infected ewes and 47 apparently uninfected ewes were examined by culture and histopathology. RESULTS: Five of five ewes with clinical ovine Johne's disease had infected foetuses. Only one of 54 subclinically affected ewes, and none of 47 uninfected ewes had an infected foetus. M a paratuberculosis was cultured from mammary secretions or mammary glands of only two of 76 ewes, both of which were clinical cases and had infected foetuses. CONCLUSION: Although intrauterine or transmammary transmission of Mycobacterium avium subsp paratuberculosis may occur frequently in clinically affected sheep, these are less common in subclinically infected ewes. Therefore these modes of transmission are unlikely to compromise existing control programs for ovine Johne's disease on most farms, especially if programs include the immediate culling of clinically affected sheep.  相似文献   

18.
Somatic cell counts, the bacteriological condition of the milk and antibodies against caprine arthritis encephalitis virus (CAEV) were measured monthly throughout lactation in 121 lactating goats of the Murcia-Granada breed in four commercial dairy goat herds. The prevalence of bacterial intramammary infection was 5.6 per cent and the prevalence of CAEV infection was 20.6 per cent. An analysis of variance revealed a significant effect of herd, intramammary infection and the interaction between intramammary infection and CAEV on the somatic cell count. In udder halves free of intramammary infection, the somatic cell counts were significantly lower in seronegative goats than in seropositive goats (P<0.05), but the difference was not significant in udder halves persistently infected by bacteria. There was a significant increase in somatic cell counts due to bacterial intramammary infection (P<0.01) in the seronegative goats, but this effect was not present in the seropositive animals.  相似文献   

19.
A survey on the prevalence and intensity of infection with gastrointestinal helminths of Dorper sheep in relation to age and weather factors was carried out on a ranch in Kajiado district, a semi-arid area of Kenya for a period of 13 months (May 1999 to May 2000). Faecal samples from lambs (3 months to 1 year), yearlings (1-2 years) and adult breeding ewes (2-4 years) were examined for helminth egg output and helminth genus composition at 3-week intervals. The results indicated that the prevalence of strongyle and tapeworms infections were highest for lambs, followed by the adult breeding ewes and then for the yearlings. In all age groups the proportions of infected animals were higher during the wet season than in the dry season for both nematodes and tapeworms. The mean strongyle egg counts were higher during the dry season for lambs, but were higher during the wet season for the other age groups. Mixed strongyle infections were detected, with Trichostrongylus (55 %), Haemonchus (28 %), Cooperia (10.5 %) and Oesophagostomum (6.5 %) being the most frequently encountered genera throughout the study period. The trends in strongyle faecal egg counts indicated the occurrence of hypobiosis, with resumption of development towards the end of the dry season and at the onset of the short rains in October and November. Self-cure was also observed in September and November in all age groups, although less frequently in lactating ewes. The prevalence and intensities of infection with gastrointestinal helminths in this area appeared to be influenced by the age of the host and weather factors.  相似文献   

20.
The interactions between leukocytes and cytokines during the acute response to intramammary infections in the dry mammary gland of sheep were studied. Dry ewes were experimentally infected in one udder half with either Staphylococcus aureus or Escherichta coli, or infused with saline as control. Udder secretion samples, blood samples and udder tissue samples were collected before and 4, 8 and 24 h after infections/infusions. Total and differential leukocyte counts were calculated in both blood and mammary secretions, and flow cytometry was used to detect the presence of CD4+, CD8+, WC1+, IL-2R+, CD18+ or L-selectin+ lymphocytes, CD18+ or L-selectin + neutrophils, and CD14+ leukocytes. Moreover, the concentrations of interleukin-1β+ (IL-1β), interleukin-8 (IL-8) and granulocyte-macrophage colony stimulating factor (GM-CSF) in udder secretions were measured using ELISA, and RT-PCR was used to detect the presence of corresponding cytokine mRNA in udder tissue biopsies. The results suggest an association between the concentrations of IL-1β, IL-8 and the intensity of neutrophil infiltration of the infected gland. Immunologically relevant changes in proportions of lymphocyte subpopulations might also occur in the acute phase of the inflammatory reaction of the udder. Greater cellular and cytokine responses to E. coli infection may have contributed to the milder clinical picture and more rapid resolution of infection than that seen for S. aureus. Enhancing the production of pro-inflammatory cytokines may improve defence against bacterial mastitis.  相似文献   

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