Methicillin‐Resistant Staphylococcus aureus (MRSA) in Three Dairy Herds in Southwest Germany

The objective of this study was to analyse the occurrence of methicillin‐resistant Staphylococcus aureus (MRSA) in three dairy herds in the southwest of Germany that had experienced individual cases of clinical and subclinical mastitis associated with MRSA. The herds were identified by the detection of MRSA during routine resistance testing of mastitis pathogens. All quarters of all cows in the herds that were positive on California Mastitis Test were sampled for bacteriological analysis on two occasions. Bulk tank milk samples were also tested. Furthermore, nasal swabs were collected from people working on the farms and from cattle. Environmental samples were collected from associated pig holdings. Isolates were characterized using spa‐typing and testing for antimicrobial resistance. Our results revealed a substantial spread of MRSA in the three dairy herds. In the first of the two investigations carried out on all cows in the three herds, milk samples of 5.1–16.7% of dairy cows were found positive for MRSA. The respective proportions in the second herd level investigation were 1.4–10.0%. Quarters harbouring MRSA had higher somatic cell counts than quarters that were negative on culture. Methicillin‐resistant Staphylococcus aureus were also detected in nasal swabs of staff (7/9), cows (7/15) and calves (4/7), bulk tank milk samples (3/3) and environmental samples from pig premises (4/5) on the farm. Herds B and C had no contact to herd A. However, in all three herds MRSA of spa‐type t011 were detected in milk samples. Results show that MRSA of spa‐type t011 is a problem in dairy farms that needs urgent attention.     

Epidemiology of Streptococcus uberis Intramammary Infections in a Dairy Herd

From 1987 to 1991, almost 36 000 quarter samples of mammary secretion representing 1790 lactations of 510 dairy cows from a research herd were collected for bacteriological examination. The percentage of cows infected with Streptococcus uberis ranged from 12 to 16 % of cows/year. S. uberis was isolated from 14.2 % of lactations over the 5-year period. The prevalence of S. uberis intramammary infection (IMI) was significantly higher in cows with ≥4 lactations than in cows with 3 or fewer lactations. Regardless of lactation number, the prevalence of S. uberis was highest before parturition, during early lactation and near drying off. The prevalence of S. uberis infected quarters ranged from 1.3 to 2.3 % of quarters/year; the prevalence rate for the 5-year period was 2 % of quarters. The quarter prevalence of S. uberis was lowest in cows with ≤3 lactations, increased significantly with lactation number and was highest in cows with ≥6 lactations. The percentage of quarters infected with S. uberis varied significantly by year. The majority (95 %) of S. uberis IMI were subclinical. The ratio of subclinical IMI to clinical IMI was lowest during early lactation, and increased with days in milk, and with lactation age except for cows in their 5th and 6th lactations. Results of this epidemiological investigation suggest that opportunities exist where suitable control measures could be applied to reduce the impact of S. uberis infections in the dairy herd.     

The Ability of the Enzyme‐Linked Immunosorbent Assay to Detect Antibody against Staphylococcus aureus in Milk following Experimental Intramammary Infection

Changes in the milk antibody levels against Staphylococcus aureus were measured at the start of an experimental intramammary instillation of either S. aureus (Study I) or Staphylococcus hyicus (Study II). A commercial enzyme‐linked immunosorbent assay system was used. Twenty‐one Holstein cows were enrolled in Study I and 15 Holstein cows were used in Study II. Pathogen instillation began 21 days before the start of the non‐lactating period. Cows received intramammary antibiotic treatment in all quarters immediately after the last milking, the start of the non‐lactating period. Lacteal secretions were collected before the start of the non‐lactating period, and during the immediate postpartum period in both studies, and during the non‐lactating period in Study I. Milk was cultured for mastitis pathogens and S. aureus antibody levels and somatic cell counts were determined from all samples. There was an approximate 2‐week delay in the elevation in antibody levels in response to the instillation of S. aureus. Antibody levels remained elevated in cows with S. aureus intramammary infections postpartum, but were below threshold in cows where intramammary infections were cured during the non‐lactating period. Antibody levels were elevated by S. hyicus intramammary infections, remained elevated for the first 12 days postpartum, but were below threshold by day 21 postpartum. Cows with incipient intramammary S. aureus infections might be misclassified as false negatives by the antibody test. However, results suggest that cows with S. hyicus intramammary infections that were not cured would not be misclassified if milk is withheld from test for the first 30 days postpartum, as recommended by the manufacturer of the test.     

Intramammary Infusion of β1,3‐glucan for Prevention and Treatment of Staphylococcus aureus Mastitis

Udder health problems associated with Staphylococcus aureus infections in dairy cows are difficult to control and antibiotics have limited effects. Lately, more interest has been directed towards ways to stimulate the innate immune mechanisms of the animal for better prevention and treatment of mastitis. The objectives of this study were to investigate if intramammary infusion at drying off with the immune modulator β1,3‐glucan can make the udder more resistant to experimental intra mammary S. aureus infection at this time, and to study if intramammary infusion of β1,3‐glucan into lactating udder quarters with chronic subclinical S. aureus infection can stimulate the clearing of the infection. Another aim was to evaluate the effect of β1,3‐glucan on the expression of major histocompatibility complex (MHC class II) on mammary leucocytes, measured by flow cytometry, during these circumstances. The results indicated a slight, but not statistically significant, positive effect of β1,3‐glucan at drying off on the clinical and anti‐bacterial response to S. aureus infection, but no therapeutic effect of β1,3‐glucan treatment of udder quarters with chronic subclinical S. aureus mastitis. However, the proportion of MHCII+ milk lymphocytes tended to increase after glucan infusion in those udder quarters indicating a stimulation of the antigen presenting ability. To further evaluate a possible preventive effect of β1,3‐glucan infusion at drying off more studies are needed involving a larger number of animals.     

Prevalence and Molecular Characteristics of Methicillin‐Resistant Staphylococcus aureus (MRSA) in Organic Pig Herds in The Netherlands

The prevalence of the methicillin‐resistant Staphylococcus aureus (MRSA) among conventional pig herds in the Netherlands is high (around 71%). Nevertheless, information about the prevalence of MRSA among organic pig herds is lacking. Here, we report a study on 24 of the 49 organic pig herds in the Netherlands. The prevalence of MRSA positive herds showed to be 21%. The genetic characteristics of the MRSA isolates were similar to MRSA CC398 described in conventional pigs except one exceptional HA‐MRSA CC30 found in one herd, which was presumably caused by human to animal transmission. This resulted in a prevalence of MRSA CC398 in the organic herds of 16.7%.     

Epidemiological study of non-contagious intramammary infections in nine commercial dairy herds following a Staphylococcus aureus control programme

Changes in prevalence in intramammary infection, by pathogen type, in herds applying a stringent contagious mastitis control programme was studied. Enrollment of 1651 lactating cows and collection of milk samples was made in this ancillary study to a cohort study of the dynamics of mastitis prevalence after adoption of a strict contagious mastitis control programme that targeted the elimination of mastitis caused by Staphylococcus aureus. Nine commercial dairies in Italy were used. Aseptic collection of milk samples from all lactating cows was performed at the time of enrollment, from all cows within 7-14 days of entering the lactating herd after the date of enrollment, and from all lactating cows at 2, 4, 7, 10 and 14 months after the date of enrollment. Prevalence of intramammary infection by pathogen type was determined from culture of milk samples. Application of the strict contagious mastitis programme did not lead to an increased risk of non-contagious mastitis. The risk of coliform, environmental streptococcal and coagulase-negative staphylococcal intramammary infections decreased after adoption of the programme. The data reported herein indicate that the overall risk for any intramammary infections decreases with adoption of a strict contagious mastitis programme, and that such a programme therefore does not necessarily lead to an increase in environmental mastitis.     

Methicillin‐resistant Staphylococcus aureus keratitis in a dog

The purpose of this study is to report a case of methicillin‐resistant Staphylococcus aureus (MRSA) keratitis in a dog. A 7‐year‐old intact male American cocker spaniel that had undergone removal of a nictitating gland was referred for severe ulcerative keratitis. Slit‐lamp examination showed swelling of the eyelid, mucopurulent discharge, conjunctival injection and chemosis, diffuse corneal edema and opacity, and a deep ulcer in central cornea. Gram staining of discharge from the eye demonstrated Gram‐positive cocci. Despite topical ofloxacin, oxytetracycline and polymyxin B ophthalmic solution and intravenous cefazolin, there was no improvement. Cultures revealed MRSA that was sensitive only to chloramphenicol, vancomycin, lincomycin, and clindamycin. The antibiotic regimen was changed to topical and systemic chloramphenicol. After 9 days of treatment, although inflammation started to be resolved, the dog developed nonregenerative anemia. The antimicrobial regimen was changed again to topical and systemic vancomycin. Inflammation continued to improve over the next week. MRSA should be considered a potential organism in infectious keratitis, especially when general antibiotics are not effective. Although topical and systemic chloramphenicol and/or vancomycin are effective for treating MRSA keratitis, vancomycin should only be used when culture and susceptibility results indicate it is appropriate and no other options are available. To our knowledge, this is the first detailed case report of MRSA keratitis in a dog.     

Methicillin‐Resistant Staphylococcus aureus from Brazilian Dairy Farms and Identification of Novel Sequence Types

The aim of this study was to investigate the phenotypic and genotypic diversity and anti‐microbial resistance among staphylococci of dairy herds that originated from Paraiba State, north‐eastern Brazil, a region where such studies are rare. Milk samples (n = 552) were collected from 15 dairy farms. Isolates were evaluated for anti‐microbial susceptibility by Kirby–Bauer disc diffusion method. Confirmation of methicillin‐resistant Staphylococcus aureus (MRSA) was performed using multiplex PCR targeting mecA and nuc genes in addition to phenotypic assay based on PBP‐2a latex agglutination. Clonal relatedness of isolates was determined by pulsed‐field gel electrophoresis (PFGE) and multilocus sequence typing (MLST) genotyping. Staphylococci were detected in 269 (49%) of the samples. Among these, 65 (24%) were S. aureus. The remaining 204 isolates were either coagulase‐negative staphylococci (n = 188; 70%) or coagulase positive other than S. aureus (n = 16; 6%). Staphylococci were cultured in seven (35%) of the 20 hand swab samples, from which five isolates were S. aureus. The isolates were most commonly resistant against penicillin (43%), ampicillin (38%) and oxacillin (27%). The gene mecA was detected in 21 S. aureus from milk and in one isolate from a milker's hand. None of the isolates were resistant to vancomycin. PFGE findings showed high clonal diversity among the isolates. Based on MLST, we identified a total of 11 different sequence types (STs 1, 5, 6, 83, 97, 126, 1583, 1622, 1623, 1624 and 1625) with four novel STs (ST1622‐ST1625). The findings show that MRSA is prevalent in milk from semi‐extensive dairy cows in north‐eastern Brazil, and further investigation on its extent in various types of milk production systems and the farm‐to‐table continuum is warranted.     

Intramammary infections in a dairy herd with a low incidence of Streptococcus agalactiae and Staphylococcus aureus infections.

In a dairy herd with a low incidence of intrammary infections due to Streptococcus agalactiae and Staphylococcus aureus, clinical mastitis remained a serious problem despite good control of nonclinical mastitis through postmilking teat disinfection and antibiotic therapy of known infected quarters at the end of lactation. During the 2-year study, the incidence of clinical mastitis was 0.88 cases/cow-year; 32.2% were caused by streptococcal species other than Str agalactiae and 33.5% by gram-negative organisms. Among all new infections detected, 54.1% were caused by streptococcal species other than Str agalactiae and 25.7% by gram-negative bacteria. Among new infections, 41.6% occurred during the nonlactating period or within a few days of calving. Incidence of clinical mastitis was highest in the 1st month of lactation. Among 84 gram-negative infections, 42.8% were caused by Klebsiella pneumoniae, 20.2% by Escherichia coli, and 23.8% by Enterobacter spp. Among the many serotypes of K pneumoniae and E coli, none was predominant.     

Relationship between Rainfall and Neospora caninum‐associated Abortion in Two Dairy Herds in a Dry Environment

The possible direct relationship between climate variations and abortion in Neospora caninum‐infected cows has not been studied. The objective of this study was to determine whether climate changes could be a risk factor for abortion in N. caninum‐infected cows, and was based on yearly serological screening for neosporosis and on the confirmation of N. caninum infection on aborted fetuses in two high‐producing dairy herds with a mean 27% seroprevalence of N. caninum antibodies. The final population study was comprised of 357 pregnancies in seropositive animals. Logistic regression analysis indicated no significant effects of herd, N. caninum antibody titre, climate variables during the first and third trimesters of gestation, mean and maximum temperature–humidity index values during the second trimester of gestation, and previous abortion on the abortion rate. Based on the odds ratio, a 1‐unit increase in lactation number yielded a 0.85‐fold decrease in the abortion rate. The likelihood of abortion was 1.9 times (1/0.54) lower for pregnant cows inseminated with beef bull semen compared with Holstein‐Friesian bull semen. The likelihood of abortion decreased significant and progressively by factors of 0.5, 0.41 and 0.3 for the respective classes 40–49, 30–39 and <30 rainfall mm during the second trimester of gestation (using the class ≥60 rainfall mm as reference). As a general conclusion, it seems that increased rainfall in a dry environment can compromise the success of gestation in N. caninum‐infected cows. Attempts should therefore be made to reduce environment effects during the second trimester of gestation, a period in which the immune response of cows is diminished.     

Patterns of Mycoplasma hyopneumoniae Infections in Belgian Farrow‐to‐Finish Pig Herds with Diverging Disease‐Course

Patterns of Mycoplasma hyopneumoniae (Mh) infections were investigated in five clinically infected herds and in five herds subclinically infected with Mh. In the clinically infected herds, housing and management conditions were good whereas these conditions were poor in the subclinically infected herds. In each herd, serum antibodies against Mh were detected in pigs of different ages and nasal swabs were taken for Mh detection using nested PCR (nPCR). The percentage of seropositive pigs in the clinically infected herds increased from 8% in pigs of 9 weeks to 52% in pigs of 18 weeks and seroconversion was most shown between 12 and 15 weeks. In the subclinically infected herds, the percentages increased from 2 to 24% and most of the pigs became seropositive between 15 and 18 weeks. The percentage of nPCR positive pigs at 6 weeks was 16 and 0% in the clinically and subclinically infected herds, respectively. The results demonstrate that the seroprevalences were higher in the clinically infected herds and that most of the pigs became infected with Mh at a younger age. It can be concluded that additional factors different from housing and management, like differences among Mh strains, may determine the infection pattern of Mh and the clinical course of the infection.     

Methicillin‐resistant Staphylococcus aureus in Resident Animals of a Long‐term Care Facility

Animals provide benefits to elderly and chronically ill people by decreasing loneliness, increasing social interactions, and improving mental health. As a result, many hospitals and long‐term care facilities allow family pets to visit ill or convalescing patients or support animal‐assisted therapy programs. These include programs that have resident animals in long‐term care facilities. Despite the benefits, there are concerns about disease transmission between pets and patients. Antibiotic‐resistant bacteria, such as methicillin‐resistant Staphylococcus aureus (MRSA), are a recognized problem in healthcare settings leading to refractory infections and potentially life‐threatening illnesses. MRSA has been isolated from numerous animal species, yet few studies are available on the carriage of this pathogen in animals residing in long‐term care facilities. Our objective was to characterize MRSA carriage among resident animals in a long‐term care facility. Methods: To document MRSA colonization, nasal swabs from 12 resident animals (one dogs and 11 cats) of a long‐term care facility were collected weekly for 8 weeks. Staphylococcus isolates were characterized by antimicrobial susceptibility and MRSA isolates were further characterized by pulsed‐field gel electrophoresis (PFGE). PFGE isolate patterns were compared with an existing database of MRSA isolate patterns at the Minnesota Department of Health. Results: Two of 11 cats were colonized with MRSA. MRSA was recovered from five of eight weekly samples in one cat and two of eight weekly samples in the other cat. All isolates were classified as USA100 (healthcare‐associated strains). Discussion: Long‐term care resident animals may acquire MRSA. Clonally related strains were identified over the 8‐week sampling period. It is unclear if pets serve as an on‐going source of infection to their human companions in long‐term care facilities.     

Assessment of Risk Factors in Milk Contamination with Staphylococcus aureus in Urban and Peri‐Urban Small‐Holder Dairy Farming in Central Ethiopia

Assessment of risk factors associated with milk production systems is central to ensuring quality and safety of milk and milk products. This study was aimed at identifying possible risk factors in milk contamination in urban and peri‐urban areas of the central high lands of Ethiopia. A total of 477 on‐farm pooled milk (n = 433) and combined bulk milk samples (n = 44) were collected and processed using standard microbiological techniques to isolate and characterize Staphylococcus aureus. In addition, 433 individual farm owners and 22 collection centre owners were interviewed using a structured and pre‐tested questionnaire. Multivariate logistic regression was used to determine risk factors. Of the total individual on‐farm pooled milk samples analysed (n = 433), it was found that 103 of the individual milk samples (24%) and 17 of the combined bulk milk (39%) were positive for S. aureus. This difference in prevalence was statistically significant. Even though there were a number of potential variables associated with the recovery of S. aureus in bovine milk, four variables including cleaning milk container with hot water and detergent [Adjusted OR: 0.342, 95% CI, (0.166, 0.701)], mastitis check [Adjusted OR: 3.019, 95% CI (1.542, 5.913)], travel time to collection centres [Adjusted OR: 4.932, 95% CI, (2.265, 10.739)] and amount of milk delivered by farmers to collection centres per day [Adjusted OR: 1.059 (1.032, 1.087 β = 0.057)] were found to be statistically significantly associated with isolation of S. aureus. We recommend a targeted educational intervention on defined risk factors to reduce the post‐harvest S. aureus contamination of raw milk in urban and peri‐urban milk shed areas of central Ethiopia.     

Longitudinal Investigation of Methicillin‐Resistant Staphylococcus aureus in Piglets

Methicillin‐resistant Staphylococcus aureus (MRSA) has emerged as an important public health concern and pigs have been implicated in human infections. Cross‐sectional studies have demonstrated that MRSA can be commonly found in pigs internationally, but little is known about age‐related changes in MRSA colonization. This study evaluated MRSA colonization in piglets in a longitudinal manner. Serial nasal swabs were collected from piglets born to 10 healthy sows. The prevalence of MRSA colonization on days 1, 3, 7, 14 and 21 was 1% (1/100), 6.2% (3/97), 8.5% (8/94), 4.4% (4/91) and 20% (18/91) respectively, with an overall pre‐weaning prevalence of 34.5%. The prevalence on days 28, 42, 56 and 70 was 34% (31/91), 65% (57/88), 50% (44/88) and 42% (36/87) respectively, with an overall post‐weaning prevalence of 85%. Eighty‐four percent of piglets from negative sows and 100% of piglets from positive sows that survived at least until the time of weaning were colonized with MRSA at one or more times during the study. There was a significant association between sow and piglet colonization. The age of the piglet was significantly associated with the probability of colonization. No piglets or sows received antimicrobials during the study period. These results indicate that age must be considered when designing surveillance programmes and interpreting results of different studies on MRSA.     

Methicillin‐Resistant Staphylococcus aureus Colonization in Personnel Attending a Veterinary Surgery Conference

Objective— To evaluate the prevalence of, and risk factors for, methicillin‐resistant Staphylococcus aureus (MRSA) colonization in veterinary personnel. Study Design— Cross‐sectional study. Sample Population— Conference attendees (n=341) at the 2008 American College of Veterinary Surgeons Symposium in San Diego California. Methods— Nasal swabs were collected and tested using selective culture for MRSA. Isolates were typed and risk factors were evaluated using questionnaire data. Results— 17.3% of subjects (17% veterinarians and 18% technicians) were MRSA positive. Colonized individuals originated from 5 different countries, predominantly the United States and Canada. Contact with small ruminants in the preceding 30 days (odds ratio [OR] 2.2), living with a person diagnosed with MRSA in the preceding year (OR 19.8) and working in a clinic where there is a specific person in charge of the infection control program (OR 2.2) were associated with colonization using multivariable analysis. Conclusion— The high rate of colonization identified here provides more evidence that MRSA exposure is likely an occupational risk for veterinary personnel. The equal rates in small animal and large animal personnel were surprising and contradict earlier studies indicating greater rates among equine personnel. The association of MRSA and small ruminant contact has not been reported previously. Clinical Relevance— MRSA is an important emerging pathogen in veterinary medicine and is a concern for both patients and veterinary personnel. The high colonization rate indicates the need to understand and control the spread of MRSA in veterinary clinics.     

Evaluation of a Neck Mounted 2‐Hourly Activity Meter System for Detecting Cows About to Ovulate in Two Paddock‐Based Australian Dairy Herds

Two studies were conducted to assess the performance of a commercially available neck‐mounted activity meter to detect cows about to ovulate in two paddock‐based Holstein‐Friesian dairy herds. The activity monitoring system recorded cow activity count in 2‐hourly periods. Study I investigated the ability of the system to detect cow ovulatory periods in dairy herds managed in two different Australian environments and breeding systems using five activity alert algorithms. Herd 1 consisted of approximately 130 milking cows calving year‐round in a sub‐tropical environment and kept in a single dry lot paddock. Herd 2 consisted of approximately 400 milking cows calving seasonally in a temperate climate and fed pasture by rotation through multiple grazing paddocks. Ovulatory periods and non‐ovulatory days were identified using milk progesterone monitoring alone or in combination with ovarian ultrasonography; using these ‘gold standards’ 141 and 135 ovulatory periods were identified in 64 and 135 cows in Herds 1 and 2 respectively. Sensitivity of the activity monitoring system for detecting cow ovulatory periods ranged from 79.4% to 94.1%, specificity from 90.0% to 98.2% and positive predictive value from 35.8% to 75.8%. Study II investigated the ability of the activity meter system to predict the timing of ovulations in paddock‐based pasture‐fed dairy cattle (Herd 2). The time of ovulation was estimated by repeat trans‐rectal ovarian ultrasonography at approximately 0, 12, 24 and 36 h after artificial insemination (AI). The mean times (±SD) from onset and end of increased activity to ovulation were 33.4 ± 12.4 and 17.3 ± 12.8 h respectively (n = 94). Fifty per cent of cows (n = 47) ovulated within the 8‐h period between 30 to 38 hs after the onset of increased activity, 76.6% (n = 72) within the 16 h between 24 to 40 h, 85.1% (n = 80) within the 24 h between 18 and 42 h and 90.4% (n = 85) within the 32 h from 19 to 51 h after the onset of increased activity. Results from these studies show that in paddock‐based dairy cows in two diverse management systems, this neck‐mounted activity meter system detects high proportions of cows that are about to ovulate and provides a useful indication of when ovulation is likely to occur. However, the specificities and positive predictive values using the algorithms assessed may be lower than desirable.     

Practical Experience with the Treatment of Recipient Mares with a Non‐Steroidal Anti‐Inflammatory Drug in an Equine Embryo Transfer Programme

As part of a commercial embryo transfer programme, 20 embryos were transferred to spontaneously synchronous or synchronized recipient mares. In 14 cases, embryo recipients were treated with non‐steroidal anti‐inflammatory drugs (NSAID), receiving flunixin meglumine i.v. at the time of transfer and vedaprofen orally twice a day on the 3 days after embryo transfer, while six embryos were transferred to untreated mares that served as controls. Out of the 14 recipient mares treated with NSAID, 11 (79%) were pregnant at 6–8 days after transfer and in 10 mares, the pregnancy was continued. From the six untreated recipients, only one became pregnant but underwent early embryonic death between day 14 and 35 after ovulation. In conclusion, pregnancy rate in NSAID‐treated recipients is higher than that in untreated recipients and above reported average values, indicating that treatment of recipient mares with NSAID helps to increase pregnancy rates after transcervical transfer and can be recommended for equine embryo transfer.     

Neospora caninum Infection Does Not Affect the Fertility of Dairy Cows in Herds with High Incidence of Neospora‐associated Abortions

This present study, was designed to establish whether Neospora caninum infection affects the fertility of high‐producing dairy cows, and was based on yearly serological screening for neosporosis and on the confirmation of N. caninum infection in aborted foetuses. Assessment was made of 7518 artificial inseminations (AI) (applied to parous cows) performed in three herds. Of these inseminations, 2540 (33.8%) resulted in pregnancy; 34% of which corresponded to seronegative cows (2226 of 6556 AI performed in seronegative cows) and 32.6% to seropositive animals (314 of 962). Abortion occurred in 97 (30.1%) of the 314 pregnancies recorded in dams seropositive for N. caninum, while only 93 (4.2%) of the 2226 pregnancies in seronegative animals ended in abortion. Logistic regression analysis indicated no significant effects of N. caninum antibody titre, days in milk and milk production at insemination on fertility. Factors found to affect fertility were herd, season of insemination, lactation and insemination number, semen‐providing bull and AI technician. Our results indicate that N. caninum infection does not affect the fertility of high‐producing dairy cows.