Risks factors associated with subclinical mastitis in water buffaloes in Pakistan

The present study was carried to ascertain the association of various risk factors of mastitis in water buffaloes. The milk samples from buffaloes were collected and screened through California Mastitis Test for the presence of mastitis. In the present study, 15.2 % prevalence of subclinical mastitis was recorded both at the government (13.4 %) and private farms (15.5 %). The chi-square analysis showed significantly higher involvement of the right rear and front quarters. The analysis of variance technique showed significant difference in live body weight, milk yield, teat end to floor distance (P?<?0.001), udder depth, teat length, and teat diameter in mastitic and healthy buffaloes. The frequency analysis also revealed significant difference between various groups including lactation stage, teat and/or udder pathology, teat shape, and udder shape (P?<?0.001). The logistic regression analysis revealed significant positive association of mastitis with milk leakage, live body weight, milk yield, parity, calf suckling, pendulous udder, number of attendants at the farm, dirty hind legs, and udder depth.     

Pathogenicity of different species of staphylococci in caprine udder

Aseptic foremilk samples were collected from Finnish landrace goats. Ten different species of staphylococci, causing subclinical infections were detected. Twelve goats with persistent subclinical staphylococcal infection were followed on a monthly basis and compared with foremilk samples of nine goats suffering from clinical mastitis. Parameters of inflammation based on the activity of the California Mastitis Test (CMT). N-acetyl-beta-D-glucosaminidase (NAGase) and antitrypsin were determined from the milk. Staphylococci were further classified using the API STAPH system. On the basis of elevations of activities of CMT, NAGase and antitrypsin, Staphylococcus aureus was the most pathogenic in clinical and subclinical mastitis, S. hyicus showed only marginal pathogenicity. Subclinical infections were persistent and the infective organism was not always detected from milk by culture. The biochemical reactions of subclinical staphylococci seemed to vary within the same gland by time. Antitrypsin was most effective in differentiating between subclinical and clinical infection. A teat cistern puncture technique was found to be suitable for the goat.     

Pharmacokinetics and pharmacodynamics of intramammary cefquinome in lactating goats with and without experimentally induced Staphylococcus aureus mastitis

Values for pharmacokinetic variables are usually obtained in healthy animals, whereas drugs are frequently administered to diseased animals. This study investigated cefquinome pharmacokinetics in healthy goats and goats with experimentally induced mastitis. Five adult lactating goats received 75 mg of cefquinome intramammary infusion using a commercially available product into one udder half in healthy goats and goats with clinical mastitis that was induced by intracisternal infusion of 100 cfu of Staphylococcus aureus ATCC 29213 suspended in 5 ml of sterile culture broth. Cefquinome concentrations were determined in plasma and skimmed milk samples using high‐performance liquid chromatography (HPLC). Pharmacodynamics was investigated using the California Mastitis Test and pH of milk. Experimentally induced mastitis significantly increased the California Mastitis Test score and pH, and decreased the maximal cefquinome concentration and shortened the half‐life in milk when compared to healthy goats. In conclusion, mastitis facilitated the absorption of cefquinome from the mammary gland of lactating goats and induced marked changes in milk pH, emphasizing the importance of performing pharmacokinetic studies of antimicrobial agents in infected animals.     

Occurrence of mastitis and associated risk factors in lactating goats under pastoral management in Borana,Southern Ethiopia

Mastitis prevalence and related risk factors were studied in 1,072 udder halves of 536 lactating goats from October, 2008 to February, 2009. Clinical and subclinical mastitis were prevalent in 4.3% (95% CI = 2.8, 6.5) and 11.2% (95% CI = 8.7, 14.3) of the studied animals, respectively, resulting in an overall prevalence of 15.5% (95% CI = 12.6, 18.9). Univariate analysis of the potential risk factors has depicted that mastitis was more prevalent in does with previous mastitis history, increased parity, poor body conditions, increased milk production, late lactation stage, long teat, and housed goats. Furthermore, prevalence was significantly higher (p < 0.05) during the wet period of October to November than the dry periods of January to February. No significant variations (p > 0.05) were observed in mastitis prevalence with udder tick infestation, mixing goat with sheep and flock size. With multivariable analysis, lactation stage, teat length, body condition, and season (wet months) have showed significant association with mastitis prevalence, and these factors maintained significant in the stepwise elimination of multivariable logistic regression model. As a result, does in late stage of lactation (OR = 4.3, 1.8, 10.4), poor body condition (OR = 5.0, 1.7, 10.0), long teats (OR = 2.2, 95% CI = 1.1, 4.2) and does examined in wet period were at higher risk of udder infections than early lactation, good body condition, short teat, and examined in dry period, respectively. The study showed occurrence of mastitis and associated risk factors in studied goats, which suggests the need for control intervention. Further investigations into pathogens involved in goat mastitis will optimize our knowledge of causative agents and control interventions.     

Immunoglobulins, lysozyme and lactoferrin in the teat and udder of the dry cow during endotoxin-induced inflammation.

Immunoglobulins (Ig) and antibacterial proteins like lysozyme and lactoferrin are components of the humoral defence against infections. Changes in Ig, lysozyme and lactoferrin concentrations during endotoxin-induced inflammation in the test cistern and udder quarter of the dry cow were studied. Surgical closure of the passage between teat and udder cisterns enabled studies of reactions in the teat cistern without interference of the mammary gland. After endotoxin infusion, IgG1, IgG2, lysozyme, and to some extent IgM, increased in the teats and udder quarters, and were positively correlated with changes in somatic cell counts. No significant changes were observed in IgA or lactoferrin. The origin and significance of Ig, lysozyme and lactoferrin in the bovine teat and udder are discussed. Ig probably originated both from serum and from local plasma cells, while leukocytes appeared to be the source of lysozyme during inflammation. Secretory epithelium appeared to be the source of lactoferrin. Support for this theory was the almost total absence of lactoferrin in teat cistern samples.     

Relationship between California Mastitis Test score and ultrasonographic teat measurements in dairy cows

Objective The majority of published studies about mastitis are related to the control and prevention of mastitis, with particular emphasis on eliminating predisposition factors. The objective of the current study was to determine the role of teat morphology as an important factor in the aetiology of mastitis. Design Ultrasonographic measurements were taken from 190 teats from 100 dairy cows of different breeds. Procedure Mastitis in cows was diagnosed by the California Mastitis Test (CMT) and microbiological tests. The data were evaluated in the light of the clinical history of the animals. Results Main effects of breed on teat diameter at the position of the Furstenberg rosette (FTD) and teat cistern diameter (CD), that of age on FTD and overall teat diameter (OTD), and that of CMT score on CD and OTD were significant (P < 0.05, P < 0.01). Number of lactations, pregnancy, the lactation period and the udder lobe (rear, front) were not found to have a significant effect on any of the measurements. Results showed that CD was significantly smaller (1.44 ± 0.04 cm) (P < 0.01) in CMT‐positive udder lobes than that in CMT‐negative lobes. No difference was detected in canal length, CD, teat wall thickness, OTD or FTD between the CMT‐positive and ‐negative lobes. Conclusion The occurrence of mastitis could be related to specific ultrasonographic teat measurements (e.g. CD, OTD and FTD) and these may be important in the breeding of cows with a predisposition to mastitis, as well in the evaluation of in‐herd cows in terms of udder/teat deformities.     

The effects of inoculation of Mannheimia haemolytica into the teat of lactating ewes

The objectives of the work described in this paper were: (i) to study the outcome of challenging ewes with Mannheimia haemolytica, at different sites of their teats, (ii) to compare the effects of two different isolates of the organism and (iii) to describe the features of the resulting lesions. Thirty-two ewes were used in the study and allocated into one of two groups (A or B, n = 16); they were challenged with one of two isolates of M. haemolytica, respectively, strain ES26L of known pathogenicity or strain VSM08L from the teat duct of a healthy ewe. Each group was further divided into four equal subgroups: the ewes in the A1/B1 subgroups were intramammarily challenged; one teat of the ewes in the A2/B2 subgroups was immersed into a broth-culture of the organisms; one teat of the ewes in the A3/B3 subgroups was inoculated 2 mm-deep, whilst one teat of the ewes in the A4/B4 subgroups was inoculated 6 mm-deep. The animals were monitored clinically, bacteriologically and cytologically before and after challenge; one animal in each subgroup was euthanised 2, 4, 7 and 11 days after challenge. All ewes in the A1/B1 subgroups developed clinical mastitis, whilst of the other animals, only one ewe in each of the A4/B4 subgroups did. Neither of the two strains used was associated with more positive bacteriological or CMT results; the A2/B2 subgroups were associated with less positive results than the A3/B3 and A4/B4 subgroups. In some ewes of the A2/B2 subgroups, mild leucocytic infiltration in the teat was evident; in the ewes of the A3/B3 subgroups, leucocytic infiltration (neutrophils, lymphocytes, plasma cells) was seen, as well as a lymphoid hyperplasia at the border between the teat duct and teat cistern; in ewes of the A4/B4 subgroups, intense subepithelial leucocytic infiltration was the salient feature. No differences were found in the severity of lesions between the two strains used or the three treatments carried out. Although strain VSM08L had been isolated from the teat duct of a healthy ewe, it caused mastitis when inoculated intramammarily; although strain ES26L is of known pathogenicity for the mammary gland, it did not cause clinical mastitis when deposited 2 mm-deep into the teat. These findings point to a protective role of the teat of ewes, which appear to limit bacterial penetration from the teat duct or cistern to the mammary gland. The lymphoid tissue, at the border between the teat duct--teat cistern, may play a significant protective role.     

Teat lesions and their relationship to intramammary infections on small-scale dairy farms in Kiambu district in Kenya

Mammary gland quarters of 139 lactating dairy cows from small-scale dairy herds were examined visually and by palpation for teat lesions and by California mastitis test (CMT) and bacterial culture for subclinical mastitis. Teat lesions were observed in 97 teats. These included teat chaps (39.2%), teat papillomas (23.7%), teat erosions (22.7%), teat fistulae (5.1%), inverted teats (5.1%) and blocked teats (4.2%). According to the CMT, the prevalence of subclinical mastitis was 33.4% in all the mammary gland quarters, 71.0% in quarters with teat lesions and 24.5% in quarters without teat lesions. There was a significant (P < 0.01) association between teat lesions and the prevalence of subclinical mastitis. The mammary gland quarters with teat lesions were 7.2 times more likely to have a positive CMT (P < 0.01) and 5.6 times more likely to have bacterial organisms (P < 0.01) isolated from them than those without any teat lesions. The bacterial organisms most frequently isolated from the CMT-positive milk samples from both the mammary gland quarters with teat lesions and those without teat lesions were Staphylococcus aureus (50.0%), Streptococcus spp. (34.8%) and Arcanobacterium pyogenes (6.2%).     

Diagnosis and treatment of mastitis in mares

Infection and inflammation of the udder (mastitis) is a common condition affecting all domestic mammals, but it appears to be less prevalent in mares than in dairy cows and dairy goats. The seemingly reduced incidence of mastitis in mares can be partially explained by the smaller size and relatively concealed location of the mare’s udder, coupled with a smaller storage capacity than cows and goats. Mastitis can affect lactating, peripartum, dry mares, mares at dry-off or prepubertal foals. Common clinical signs include swollen mammary tissue, abnormal mammary gland secretion, fever and anorexia; less common signs are hindlimb lameness and a swollen mammary vein. On rare occasions, mastitis pathogens can severely affect the nursing foal and mares may develop fibrotic tissue and consequent agalactia in the side(s) or quarter(s) affected. Based on the clinical presentation, mastitis can be classified as acute or chronic, and clinical or subclinical. Diagnosis is based on the clinical signs aided with aerobic culture and cytological evaluation of the gland secretion. In addition, these ancillary tests can also be used to assess prognosis and duration of treatment. Mares suffering from mastitis may present neutrophilia and hyperfibrinogenaemia. Treatment for mastitis includes antimicrobial therapy (systemic and/or locally), nonsteroidal anti-inflammatory drugs, frequent milking and cold hosing with/without hot-packing applied on the gland. While the frequent monitoring of mares after weaning and reducing food intake should be part of common practices at weaning, cleaning of the udder, control of insect populations and frequent milking of mares with a foal unable to nurse can also aid in preventing mastitis.     

Microbiological colonisation of bovine teat canal--significance and influencing factors

The teat canal of lactating dairy cattle is of particular importance for the defence of facultative pathogenic and pathogenic microorganisms (e.g., staphylococci) invading the bovine udder. Furthermore the canal is usually colonized with microorganisms, too. In addition to microorganisms inhibiting mastitis pathogens the teat canal is colonized by staphylococci. The microbial colonization can be influenced by the environment of the animals, the care and disinfection of the teat skin and indirectly by the effects of forces being associated with machine milking. Because of vacuum fluctuations occurring under the teat tip microorganisms, which colonize the teat canal, can invade the bovine mammary gland and cause infections there. This paper gives a review of the microbial colonization of the bovine teat duct and of influencing factors on the microbial populations as well as of the significance of the teat canal colonization for the development of mastitis.     

Clinical and histopathological aspects of naturally occurring mastitis caused by Listeria monocytogenes in cattle and ewes

Listeria monocytogenes was isolated from the milk of two cows and two sheep with mastitis in one quarter and one udder half. The animals were observed over a period of 2-12 months. Clinical examination of the udder, bacteriological examinations and determination of somatic cell counts of milk samples were performed monthly. All four cases suffered from a subclinical mastitis characterized by an elevated somatic cell count (0.8-10.1 x 10(6) cells/ml), a persistent shedding of Listeria and by a normal appearance of the milk. The animals did not show any systemic reaction, but all animals developed an atrophy of the infected mammary gland. Histological examinations revealed a chronic interstitial mastitis with diffuse infiltration of lymphocytes, plasma cells and macrophages. All internal organs showed no abnormalities, no Listeria could be isolated. Listeria could however be isolated from the affected mammary parenchyma and from the mammary lymph node. The results of the bacteriological examination could be confirmed by means of PCR. Using PFGE, all the isolates from the same animal were identical. Immunohistochemical examination of the ovine mammary glands achieved a very strong immunoreactivity for CD5 cells. The mode of infection and the reaction of the immune system's defense of the ovine udders are discussed.     

Enhanced Erythrocytic Lipid Peroxides and Reduced Plasma Ascorbic Acid,and Alteration in Blood Trace Elements Level in Dairy Cows with Mastitis

Oxidative stress has been associated in several inflammatory conditions and incriminated in the pathogenesis of many diseases. However, little information is available on the status of plasma antioxidant levels, essential components of important antioxidant enzymes such as copper, zinc and selenium in blood, and the end product of oxidative damage to the erythrocytic polyunsaturated fatty acids in inflammatory udder conditions. Blood samples were collected from three groups of dairy cows, with 21 in each group: animals with healthy udder, clinical mastitis, and subclinical mastitis. These animals were randomly selected from a herd on the basis of the California mastitis test, somatic cell count and total bacterial count. The mean plasma ascorbic acid concentration was significantly lower in cows with subclinical (p = 0.004) and clinical mastitis (p = 0.000) and the erythrocytic lipid peroxide levels were significantly (p = 0.000) higher in clinical mastitis as compared to controls. There was a significant decrease in mean blood zinc concentration in subclinical (p = 0.005) and clinical mastitis (p = 0.000), but an increase in mean blood copper level in the clinical mastitis group. It was concluded that the blood antioxidant status declines in inflammatory udder conditions, suggesting that incorporation of antioxidants may help in better management of mastitis in dairy cows.     

Clinical and ultrasonographic findings in the mammary gland of sheep

AIM: To compare clinical and ultrasonographic findings and assess the value of ultrasonography for evaluating the structure and condition of the teat and teat canal of sheep. METHODS: The mammary glands of 30 lactating ewes were examined clinically and using ultrasonography. The distance from the teat tip to the ground was measured and diagnostic images of the body of the gland, gland cistern and teat cistern were obtained using an 8.5 MHz frequency ultrasonic transducer. A California mastitis test (CMT) and bacteriological culture were performed on milk samples collected from each half of each udder. RESULTS: Udder parenchyma and teats were palpably normal in 27/30 (90%) ewes. Milk clots or abnormalities were evident in 4/30 (13%) udders, lesions in the glandular parenchyma and/or teats were evident by palpation in 3/30 (10%), and pathogenic bacteria were cultured from 2/30 (7%). In both of the latter cases, mastitis was diagnosed based on clotted and discoloured appearance of milk and highly positive CMT reactions. Ultrasonographic examination in these udders revealed non-homogenous regions in the glandular tissue and alternating areas of hyperechogenic and hypoechogenic tissue. Overall, highly positive CMT reactions were evident in milk from 14/30 (47%) left halves and 9/30 (30%) right halves (p=0.02). No relationship between teat-to-ground distances and CMT results was evident (p>0.05). Teat canal lengths ranged from 5.7-10.3 mm (mean=8.6; SD=1.3 mm) and the widths from 1.8-3.1 mm (mean=2.3; SD=0.4 mm). Milk sampled from ewes that had long (> or = 9 mm) or wide (> or = 2 mm) teat canals was highly positive to the CMT in 75% and 83% of cases, respectively. CONCLUSIONS: Ultrasonographic measurements of the length and width of the teat canal appeared to correlate with CMT results. The use of ultrasonography in evaluating the health of the udder of small ruminants holds promise for the future.     

Udder health in relation to udder and teat morphometry in Holstein Friesian × Sahiwal crossbred dairy cows

The present investigation involved 261 Holstein Friesian (HF) × Sahiwal cows to study the udder health as well as the udder and teat morphometry. The udder health was defined on the basis of bacteriology and California mastitis test of quarter foremilk. The morphometry parameters included udder fore depth (UFD, distance from the point where the fore udder merges within the abdomen to a point in front of the fore teats at the level of the udder base), udder rear depth (URD, distance from the bottom of the vulva to the base of the rear udder), udder depth (UD, level of the udder base with respect to hock joint), height of the udder from the floor, teat length, teat diameter (at mid of the teat barrel), teat-tip to floor distance and distance between the teats. The URD, UD and height of udder from the floor showed a significant (P?<?0.05) relation to the udder health with mastitic cows having larger URD, smaller udder distance from the floor and the udder base placed below the hock joint. The cows with teat length larger than 4.5 cm and teat diameter 3.0 cm or larger had significantly more quarters affected with mastitis. Further, cows with teats placed nearer to the floor were more susceptible to mastitis (P?<?0.01). No significant differences were found between healthy and mastitic udders with respect to UFD and distance between teats. It can be concluded that selection for optimum udder and teat morphometry in breeding programmes may help to reduce susceptibility to intramammary infections in HF × Sahiwal cows.     

Clinical and ultrasonographic findings in the mammary gland of sheep

AIM: To compare clinical and ultrasonographic findings and assess the value of ultrasonography for evaluating the structure and condition of the teat and teat canal of sheep.

METHODS: The mammary glands of 30 lactating ewes were examined clinically and using ultrasonography. The distance from the teat tip to the ground was measured and diagnostic images of the body of the gland, gland cistern and teat cistern were obtained using an 8.5 MHz frequency ultrasonic transducer. A California mastitis test (CMT) and bacteriological culture were performed on milk samples collected from each half of each udder.

RESULTS: Udder parenchyma and teats were palpably normal in 27/30 (90%) ewes. Milk clots or abnormalities were evident in 4/30 (13%) udders, lesions in the glandular parenchyma and/or teats were evident by palpation in 3/30 (10%), and pathogenic bacteria were cultured from 2/30 (7%). In both of the latter cases, mastitis was diagnosed based on clotted and discoloured appearance of milk and highly positive CMT reactions. Ultrasonographic examination in these udders revealed non-homogenous regions in the glandular tissue and alternating areas of hyperechogenic and hypoechogenic tissue. Overall, highly positive CMT reactions were evident in milk from 14/30 (47%) left halves and 9/30 (30%) right halves (p=0.02). No relationship between teat-to-ground distances and CMT results was evident (p>0.05). Teat canal lengths ranged from 5.7–10.3 mm (mean=8.6; SD=1.3 mm) and the widths from 1.8–3.1 mm (mean=2.3; SD=0.4 mm). Milk sampled from ewes that had long (≥9 mm) or wide (≥2 mm) teat canals was highly positive to the CMT in 75% and 83% of cases, respectively.

CONCLUSIONS: Ultrasonographic measurements of the length and width of the teat canal appeared to correlate with CMT results. The use of ultrasonography in evaluating the health of the udder of small ruminants holds promise for the future.     

The prevalence of subclinical mastitis in dairy goats in Kenya

California mastitis test (CMT), direct leukocytes counts and bacteriological examination were performed on 630 milk samples from apparently healthy mammary glands of dairy goats comprising a mixed population of German Alpine, Toggenberg, Saanen and Galla crosses to find the prevalence of subclinical mastitis. The prevalence of subclinical mastitis was 9.8% according to CMT, 9.7% according to direct leukocyte counts and 28.7% by bacterial isolation during a 3-month period. The proportion of the bacteriologically positive milk samples was significantly (P <0.01) higher than that positive for CMT and direct leukocyte counts. There was a significant (P < 0.01) correlation between CMT and direct leukocyte counts. There was no significant direct relationship between bacterial isolation and CMT Bacterial organisms were isolated in 22.5% of the 568 CMT-negative milk samples. The results suggest that bacterial organisms isolated from the CMT-negative milksamples were either latent infections or did not stimulate any significant increase in somatic cell counts that could be detected by either the CMT or direct leukocyte counts. The observations of this study indicate that the mere presence of bacteria in goat's milk does not mean that the udder is infected and so does not warrant antibiotic therapy.     

硒与奶牛隐性乳房炎相关性的研究进展

奶牛乳房炎是我国奶牛疾病中发病率最高的疾病之一,严重影响奶牛产奶量和乳制品质量,给奶牛养殖业造成巨大经济损失。有证据表明,多种营养物质的缺乏都会增加奶牛隐性乳房炎的发病率。其中,微量元素硒能改善奶牛乳腺免疫功能,对奶牛乳腺健康和降低隐性乳房炎发病率具有重要意义。主要阐述硒与奶牛隐性乳房炎的相关性,以期为通过调控乳腺免疫功能和防控乳腺炎提供依据。     

The influence of intramammary antibiotic treatment, presence of bacteria, stage of lactation and parity in dairy goats as measured by the California Milk Cell Test and somatic cell counts

The California Milk Cell Test (CMCT) and somatic cell counts (SCC) on their own were not reliable methods in the identification of subclinical mastitis in the dairy goats studied and should be accompanied by microbiological tests. However, CMCT and SCC were indicators of irritation of the udder parenchyma. In healthy goats Spectrazol Milking Cow (Schering-Plough AH) caused the least and Curaclox LC (Norbrook (ARK AH)) the most irritation of parenchyma after intramammary treatment. The effects of Rilexine 200 LC (Logos Agvet (Virbac)) were intermediate. There was a highly significant difference (P < 0.001) in the mean log SCC between treated and control groups for goats treated with Curaclox LC and Rilexine 200 LC but no significant difference was present in the mean log SCC of treatment and control groups for goats treated with Spectrazol Milking Cow at the 07:00 and at 19:00 samplings. The CMCT was an indicator of the level of SCC in goat milk. The CMCT was more useful in confirming the absence of infection, rather than in diagnosing mastitis.     

Epidemiology of mammary gland disorders in multiparous Finnish Ayrshire cows

Logistic regression was used to investigate the effects of host characteristics, milk production and 23 veterinary diagnoses on the odds of contracting acute and chronic mastitis, and teat injury among 41 989 multiparous Finnish Ayrshire cows that calved during 1983.

Cows which had higher previous-lactation milk yields were at increased risk of acute and chronic mastitis, and teat injury. All of the mammary gland disorders were directly interrelated. Abomasal disorder, indoor hypomagnesemia, prolapsed uterus and vagina, and abortion were not risk factors for any of the three mammary gland disorders; however, retained placenta, udder edema, ketosis, non-parturient paresis, rumen acidosis, traumatic reticuloperitonitis, silent heat, ovarian cyst and other types of infertility were all direct risk factors for at least two mammary gland disorders.     

Transmission of Mannheimia haemolytica from the tonsils of lambs to the teat of ewes during sucking

Objective of the work was to study whether Mannheimia haemolytica may be transmitted from the mouth of the lambs into the teat of the dam during sucking. We compared bacterial populations within the teat duct and milk of ewes immediately before and immediately after sucking by the lambs. Tonsils of lambs of the ewes were swabbed. M. haemolytica strain DAG21T recovered from a teat duct of a ewe was compared to strain DAG21R recovered from the tonsils of her lamb by using 16s rRNA sequencing. We used those two isolates and another one of known pathogenicity, for challenging ewes: (i) 2-mm deep into healthy teats, (ii) 2-mm deep into teats with chapping lesions or (iii) into the cistern of healthy mammary glands. Of samples collected before suckling, 20/792 were bacteriologically positive, and of those after, 50/792 were bacteriologically positive (P < 0.001); in 37 cases, a negative sample became positive. One M. haemolytica (DAG21T) was recovered after suckling from a teat duct of a ewe. The organism was isolated from 57/90 tonsillar swabs from lambs. Risk of infection of ewe’ teats was 0.004 throughout lactation, being greatest (0.021) during the 3rd week of lactation. The 16s rRNA sequences of strains DAG21T and DAG21R were identical over 1450 nucleotides. Phylogenetic analysis showed that the two isolates clustered together with isolates of M. haemolytica. Organism deposition into healthy teats caused subclinical mastitis; deposition into teats with lesions or directly into mammary gland caused clinical mastitis. When results of inoculation of the three strains were compared between them, statistical significance was always P > 0.9. Results provide clear evidence that suckling by lambs can lead to transmission of M. haemolytica into the teats of the ewes; the bacteria have the potential to cause mastitis if circumstances are favourable.