Antimicrobial susceptibility of staphylococci from bovine milk samples in routine microbiological mastitis analysis in Finland.

The most frequent reason for antimicrobial use in dairy herds is mastitis and knowledge about mastitis-causing pathogens and their antimicrobial susceptibility should guide treatment decisions. The overall objective of this study was to assess antimicrobial resistance (AMR) of staphylococci in mastitic milk samples in Finland. MALDI-ToF MS identified a total of 504 Staphylococcus isolates (260 S. aureus and 244 non-aureus staphylococci, NAS) originating from bovine mastitic milk samples. Phenotypic susceptibility against cefoxitin, ceftiofur, enrofloxacin, gentamycin, oxacillin, penicillin, and tetracycline was evaluated by disk diffusion method and the presence of blaZ, mecA, and mecC genes investigated by PCR. Nitrocefin test assessed these isolates' beta-lactamase production. The most common NAS species were S. simulans, S. epidermidis, S. chromogenes, and S. haemolyticus. In total, 26.6% of the isolates (18.5% of S. aureus and 35.2% of all NAS) carried the blaZ gene. Penicillin resistance, based on disk diffusion, was lower: 18.8% of all the isolates (9.3% of S. aureus and 28.9% of all NAS) were resistant. Based on the nitrocefin test, 21.5% of the isolates produced beta-lactamase (11.6% of S. aureus and 32.0% of all NAS). Between the Staphylococcus species, the proportion of penicillin-resistant isolates varied, being lowest in S. simulans and highest in S. epidermidis. Resistance to antimicrobials other than penicillin was rare. Of the eight NAS isolates carrying the mecA gene, six were S. epidermidis. One S. aureus isolate carried the mecC gene. Agreement beyond chance, assessed by kappa coefficient, between phenotypic and genotypic resistance tests, was moderate to substantial. Some phenotypically penicillin-susceptible staphylococci carried the blaZ gene but isolates without blaZ or mec genes rarely exhibited resistance, suggesting that the more reliable treatment choice may depend upon genotypic AMR testing. Our results support earlier findings that penicillin resistance is the only significant form of antimicrobial resistance among mastitis-causing staphylococci in Finland.

Invited review: Selective treatment of clinical mastitis in dairy cattle.

Treatment of clinical mastitis (CM) and use of antimicrobials for dry cow therapy are responsible for the majority of animal-defined daily doses of antimicrobial use (AMU) on dairy farms. However, advancements made in the last decade have enabled excluding nonsevere CM cases from antimicrobial treatment that have a high probability of cure without antimicrobials (no bacterial causes or gram-negative, excluding Klebsiella spp.) and cases with a low bacteriological cure rate (chronic cases). These advancements include availability of rapid diagnostic tests and improved udder health management practices, which reduced the incidence and infection pressure of contagious CM pathogens. This review informed an evidence-based protocol for selective CM treatment decisions based on a combination of rapid diagnostic test results, review of somatic cell count and CM records, and elucidated consequences in terms of udder health, AMU, and farm economics. Relatively fast identification of the causative agent is the most important factor in selective CM treatment protocols. Many reported studies did not indicate detrimental udder health consequences (e.g., reduced clinical or bacteriological cures, increased somatic cell count, increased culling rate, or increased recurrence of CM later in lactation) after initiating selective CM treatment protocols using on-farm testing. The magnitude of AMU reduction following a selective CM treatment protocol implementation depended on the causal pathogen distribution and protocol characteristics. Uptake of selective treatment of nonsevere CM cases differs across regions and is dependent on management systems and adoption of udder health programs. No economic losses or animal welfare issues are expected when adopting a selective versus blanket CM treatment protocol. Therefore, selective CM treatment of nonsevere cases can be a practical tool to aid AMU reduction on dairy farms.

Selective treatment of nonsevere clinical mastitis does not adversely affect cure, somatic cell count, milk yield, recurrence, or culling: A systematic review and meta-analysis.

Treatment of clinical mastitis (CM) contributes to antimicrobial use on dairy farms. Selective treatment of CM based on bacterial diagnosis can reduce antimicrobial use, as not all cases of CM will benefit from antimicrobial treatment, e.g., mild and moderate gram-negative infections. However, impacts of selective CM treatment on udder health and culling are not fully understood. A systematic search identified 13 studies that compared selective versus blanket CM treatment protocols. Reported outcomes were synthesized with random-effects models and presented as risk ratios or mean differences. Selective CM treatment protocol was not inferior to blanket CM treatment protocol for the outcome bacteriological cure. Noninferiority margins could not be established for the outcomes clinical cure, new intramammary infection, somatic cell count, milk yield, recurrence, or culling. However, no differences were detected between selective and blanket CM treatment protocols using traditional analyses, apart from a not clinically relevant increase in interval from treatment to clinical cure (0.4 d) in the selective group and higher proportion of clinical cure at 14 d in the selective group. The latter occurred in studies co-administering nonsteroidal anti-inflammatories only in the selective group. Bias could not be ruled out in most studies due to suboptimal randomization, although this would likely only affect subjective outcomes such as clinical cure. Hence, findings were supported by a high or moderate certainty of evidence for all outcome measures except clinical cure. In conclusion, this review supported the assertion that a selective CM treatment protocol can be adopted without adversely influencing bacteriological and clinical cure, somatic cell count, milk yield, and incidence of recurrence or culling.

Invited review: Selective use of antimicrobials in dairy cattle at drying-off.

Administering intramammary antimicrobials to all mammary quarters of dairy cows at drying-off [i.e., blanket dry cow therapy (BDCT)] has been a mainstay of mastitis prevention and control. However, as udder health has considerably improved over recent decades with reductions in intramammary infection prevalence at drying-off and the introduction of teat sealants, BDCT may no longer be necessary on all dairy farms, thereby supporting antimicrobial stewardship efforts. This narrative review summarizes available literature regarding current dry cow therapy practices and associated impacts of selective dry cow therapy (SDCT) on udder health, milk production, economics, antimicrobial use, and antimicrobial resistance. Various methods to identify infections at drying-off that could benefit from antimicrobial treatment are described for selecting cows or mammary quarters for treatment, including utilizing somatic cell count thresholds, pathogen identification, previous clinical mastitis history, or a combination of criteria. Selection methods may be enacted at the herd, cow, or quarter levels. Producers' and veterinarians' motivations for antimicrobial use are discussed. Based on review findings, SDCT can be adopted without negative consequences for udder health and milk production, and concurrent teat sealant use is recommended, especially in udder quarters receiving no intramammary antimicrobials. Furthermore, herd selection should be considered for SDCT implementation in addition to cow or quarter selection, as BDCT may still be temporarily necessary in some herds for optimal mastitis control. Costs and benefits of SDCT vary among herds, whereas impacts on antimicrobial resistance remain unclear. In summary, SDCT is a viable management option for maintaining udder health and milk production while improving antimicrobial stewardship in the dairy industry.

The Impact of Overstocking and Negative Energy Balance on Quantitative Measurement of Non-typhoidal Salmonella in Periparturient Dairy Cattle.

Stressful conditions in animal production facilities may exacerbate the fecal shedding and foodborne transmission of non-typhoidal Salmonella enterica subsp. enterica. Dairy cows are reservoirs of this zoonotic microorganism, and its prevalence has roughly doubled in the past decade on dairy farms in United States. Dairy cows are commonly overstocked at the feed bunk, and stressors placed on the animal prior to parturition may exacerbate Salmonella shedding. However, no studies have evaluated the impact of overstocking and metabolic stress on fecal concentrations of the pathogen. Therefore, we conducted a field trial with 120 multiparous dairy cows randomized into one of four treatment groups with different stocking densities at the feed bunk during the periparturient period as follows: US, understocked from -60 to -1 DRC; OS, overstocked from -60 to -1 DRC; USOS, understocked from -60 to -26 DRC/overstocked from -25 to -1 DRC; and OSUS, overstocked from -60 to -26 DRC/ understocked from -25 to -1 DRC. Fecal and blood samples were collected at four time points relative to calving. qPCR assays were used to quantify Salmonella invA gene and total bacterial community from fecal samples, and a subset of isolates recovered from fecal bacterial culture were characterized using pulsed field gel electrophoresis and serotyping. Serum non-esterified fatty acids (NEFA) were measured as a metabolic stress indicator using an immunoassay. Multivariable analyses were performed to test if changes in Salmonella concentrations were associated with stocking density, energy balance, or days relative to calving. From fecal isolates, three Salmonella serovars were identified, S. Cerro; Kentucky; Meleagridis. Concentrations of Salmonella increased as cows approached calving. Higher stocking densities at the feed bunk did not impact total bacterial community or NEFA; however, cows in the overstocked groups had higher Salmonella fecal concentrations. Further, cows with higher NEFA concentrations after calving had a higher likelihood of detection of Salmonella. Future farm interventions should aim to reduce environmental and metabolic stress during the periparturient period to decrease the dissemination of Salmonella to cattle, the environment, and humans.

Prevalence of digital dermatitis using mirror scoring in Finnish freestall dairy herds.

Digital dermatitis (DD) is a severe bacterial hoof disease found worldwide. The disease can be classified into 5 different stages, denoted as M1 to M4 and M4.1, by clinical examination. The main objective of this study was to estimate prevalence of DD lesions in Finnish freestall dairy cattle population through hind feet inspection of standing cows with a mirror. Another aim was to estimate the sensitivity and specificity of mirror scoring on standing cows in a pen or in a milking parlor without washing the feet. Three veterinarians visited 81 randomly selected herds across the country. During the herd visits, hind feet of standing cows (n = 7,010) were scored with a mirror without washing the feet, either when the cows were standing in a pen (n = 4,992) or in the milking parlor (n = 2018). In total, 128 cows (111 from pen and 17 from milking parlor) including 256 feet were chosen with cross-sectional sampling and scored in a trimming chute. Animal-level sensitivity for scoring M2 lesions with a mirror was 55% and specificity was 97%; for all active DD lesions (M1, M2, or M4.1), sensitivity was 36% and specificity was 96%. Sensitivity for scoring any DD lesions was 90% and specificity was 82%. The bias-corrected sensitivity and specificity for scoring any DD lesions were 79% and 92%, respectively. The bias-corrected sensitivity and specificity for scoring M2 DD lesions were 10% and 100%. We found M2 lesions in 12.1% of the study herds, and true herd-level prevalence was the same. Altogether, 33.3% (true prevalence 28.4%) of the herds had either M1, M2, or M4.1 DD lesions. However, only 0.7% (true prevalence 5.4%) of cows in total had active M2 lesions. The within-herd prevalence of M2 lesions (in herds where at least 1 cow had a M2 lesion) was 5.7% and varied between 0.4% and 18.8%. Herds with active DD lesions also had more any DD lesions than herds without active DD lesions. The herd-level prevalence was higher than previously thought, with only 1 herd without any DD lesions. However, the animal-level prevalence of active DD lesions was relatively low. Farmers and veterinarians need to be informed of the disease and possible control measures. Because of the low within-herd prevalence, the control of the disease might be easier than in countries where DD is widespread. Further studies are needed to identify factors associated with DD prevalence in Finnish dairy herds.

Risk factors for equine intestinal parasite infections and reduced efficacy of pyrantel embonate against Parascaris sp.

Gastrointestinal parasites, Parascaris sp. and strongyles, are common in young horses worldwide and control of these parasites is challenged by increasing anthelmintic resistance. Our aim was to identify risk factors for these infections as well as to assess the efficacy of fenbendazole (dose 7.5 mg/kg) and pyrantel embonate (dose 19 mg/kg) against Parascaris sp. We also evaluated association between owner observed symptoms and patent infections with these parasites. Fecal samples were collected from 367 young horses in Finland and a questionnaire study was conducted. Fecal egg counts were performed by Mini-FLOTAC® method. Univariable logistic regression models using patent infection status (Yes/No), separately for Parascaris sp. and strongyle infections as an outcome were run initially to screen potential risk factors collected by the questionnaire. After the initial screening, multiple logistic regression models were constructed and run to account for correlated data structure, risk factors and potential confounders simultaneously. Two significant risk factors for a patent Parascaris sp. infection were found: breeding farm size (p = 0.028) and frequency of horse movements (p = 0.010). Horses originating from large breeding farms were more likely (OR = 2.47, 95% confidence interval (CI) 1.10-5.51) to shed Parascaris sp. eggs upon relocation to training stables compared to horses originating from small breeding farms. Horses living in farms with frequent horse movements to other premises had higher odds (OR = 3.56, 95% CI: 1.35-9.39) of a patent Parascaris sp. infection compared to farms with less frequent horse movements. Risk factors for patent strongyle infection included age (p < 0.001) and season (p = 0.017). Horses were less likely (OR = 0.27, 95% CI: 0.10 - 0.66) to shed strongylid eggs during the spring compared to the winter. Horses excreting over 200 ascarid eggs per gram were included in the anthelmintic efficacy trial. A mean FECR less than 90% was interpreted as presence of anthelmintic resistance. The mean FECR was 98.5% (95% CI: 95.8-100) and 68.0% (95% CI: 52.7-83.3) in the fenbendazole (n = 31) and pyrantel (n = 26) treatment groups, respectively. In conclusion, we identified two new risk factors for patent Parascaris sp. infection; breeding farm size and frequency of horse movements. Reduced efficacy of pyrantel against Parascaris sp. was observed for the second time in Europe. A relatively high Parascaris sp. prevalence in yearlings (34%) and two-year-olds (20%) was observed, which has not been reported earlier. An association between symptoms and a patent Parascaris sp. infection was observed in foals.

Bacteriology and cytology of otic exudates in 41 cavalier King Charles spaniels with primary secretory otitis media.

BACKGROUND: Primary secretory otitis media (PSOM) in the cavalier King Charles spaniel (CKCS) is similar to otitis media with effusion (OME) in humans. A proposed aetiology of OME is inflammation of the middle ear mucosa, usually due to bacterial infection, leading to auditory tube dysfunction. HYPOTHESIS/OBJECTIVES: Our objective was to characterize the microbiological and cytological findings of otic exudates from the external ear canal (EEC) (n = 68) and middle ear (ME) (n = 69) from 41 CKCSs with PSOM. METHODS AND MATERIALS: Swab samples from the EEC and mucus aspirated from the ME after performing a myringotomy were obtained for bacterial culture and cytological analysis. RESULTS: Fifty-five of 68 (81%) EEC and 46 of 69 (67%) ME yielded no bacterial growth. Thirty-eight of the 68 (56%) ears had no microbial growth from neither the EEC nor ME; seven (10%) had bacteria isolated from the EEC only; 17 (25%) had bacteria isolated from the ME only, and six (8%) had bacteria isolated from both EEC and ME. Thirty-four total bacterial isolates were cultured from ME. The most common bacterial species isolated were coagulase-negative staphylococci, followed by Staphylococcus pseudintermedius. Otic cytology identified coccoid organisms in only three of 68 EEC and four of 69 ME. CONCLUSIONS: The role of bacteria in the pathogenesis of PSOM in CKCS is unclear. The majority of the EEC and ME of the CKCS with PSOM were negative by conventional bacterial culture and the cytological presence of bacteria was not correlated with culture positives. The potential role of noncultivable microbiota in PSOM requires exploration using molecular methods.

Conductive hearing loss in four dogs associated with the use of ointment-based otic medications.

BACKGROUND: Hearing loss (HL) is classified as conductive when sound transmission is compromised in the ear canal or middle ear, or sensorineural when there is an abnormality of the receptor cells of the cochlea or auditory pathway. Hearing in dogs is evaluated using the brainstem auditory evoked response (BAER) test. HYPOTHESIS/OBJECTIVES: Our objective was to characterize BAER findings pre- and post-ear flushing in four dogs with acute HL following application of an ointment-based otic medication containing betamethasone, clotrimazole and gentamicin in a mineral oil-based system containing a plasticized hydrocarbon gel. ANIMALS: Dogs, ranging from 9 to 11 years old, that had been treated with the otic medication for one to three weeks prior to hearing loss and on otoscopic examination had evidence of medication in the horizontal ear canals. METHODS: Dogs were anaesthetized for an ear flush to remove the medication from the ear canals. Hearing was assessed using BAER testing, measurements were initiated with 116 decibel peak equivalent sound pressure level (dBpeSPL) click. Estimated threshold was defined as the lowest intensity in dB in which wave V was still present. RESULTS: Post-ear flush the estimated threshold improved in both ears of all dogs (mean 22.3 dB; range 13-41 dB), confirming conductive HL due to the otic medication. All owners noted an improvement in their dog's hearing post-ear flush, validating the BAER findings. CONCLUSIONS AND CLINICAL IMPORTANCE: These results emphasize the importance of an ear flush to remove otic medications in dogs that experience acute HL, to determine if the HL is conductive, and if so, to restore hearing.

Movement patterns of exhibition swine and associations of influenza A virus infection with swine management practices.

OBJECTIVE To identify the geographic distribution of exhibition swine in the Midwestern United States, characterize management practices used for exhibition swine, and identify associations between those practices and influenza A virus (IAV) detection in exhibition swine arriving at county or state agricultural fairs. DESIGN Cross-sectional survey. SAMPLE 480 swine exhibitors and 641 exhibition swine. PROCEDURES Inventories of swine exhibited at fairs in 6 selected Midwestern states during 2013 and of the total swine population (including commercial swine) in these regions in 2012 were obtained and mapped. In 2014, snout wipe samples were collected from swine on arrival at 9 selected fairs in Indiana (n = 5) and Ohio (4) and tested for the presence of IAV. Also at fair arrival, swine exhibitors completed a survey regarding swine management practices. RESULTS Contrary to the total swine population, the exhibition swine population was heavily concentrated in Indiana and Ohio. Many swine exhibitors reported attending multiple exhibitions within a season (median number, 2; range, 0 to 50), with exhibited swine often returned to their farm of origin. Rearing of commercial and exhibition swine on the same premises was reported by 13.3% (56/422) of exhibitors. Hosting an on-farm open house or sale was associated with an increased odds of IAV detection in snout wipe samples. CONCLUSIONS AND CLINICAL RELEVANCE The exhibition swine population was highly variable and differed from the commercial swine population in terms of pig density across geographic locations, population integrity, and on-farm management practices. Exhibition swine may be important in IAV transmission, and identified biosecurity deficiencies may have important public and animal health consequences.

Diagnosis of primary secretory otitis media in the cavalier King Charles spaniel.

BACKGROUND: Primary secretory otitis media (PSOM) is a disease reported in the cavalier King Charles spaniel (CKCS). The diagnosis of PSOM has been made based only on visualization of a bulging tympanic membrane and mucus in the middle ear post-myringotomy. No additional tests have been evaluated for the diagnosis of PSOM; CKCSs with early disease may have been missed. HYPOTHESIS/OBJECTIVES: The objective of this study was to compare otoscopy, tympanometry, pneumotoscopy and tympanic bulla ultrasonography, using computed tomography (CT) as the gold standard for the diagnosis of PSOM in the CKCS. ANIMALS: Sixty CKCSs with clinical signs suggestive of PSOM. METHODS: Otoscopy, CT scan, tympanic bulla ultrasonography, tympanometry and pneumotoscopy were performed; those CKCSs with a soft tissue density in the middle ear identified on CT had a myringotomy and middle ear flush. RESULTS: Forty-three (72%) CKCSs had PSOM (30 bilateral, 13 unilateral). A large bulging pars flaccida was identified in only those CKCS with PSOM (specificity of 100%); however, only 21 of 73 ears with PSOM had a large bulging pars flaccida (sensitivity of 29%). Sensitivity and specificity for tympanometry, pneumotoscopy and tympanic bulla ultrasonography were (84%, 47%), (75%, 79%) and (67%, 47%), respectively. CONCLUSIONS AND CLINICAL IMPORTANCE: Based on these results a large bulging pars flaccida indicates the presence of PSOM, whereas a flat pars flaccida may be present in CKCS that have PSOM as well as those that do not. In CKCSs with a flat pars flaccida none of the above diagnostic tests can be recommended in place of CT scan for the diagnosis of PSOM.

Effect of feeding on the pharmacokinetics of oral minocycline in healthy research dogs.

BACKGROUND: The effect of food on minocycline oral absorption in dogs is unknown. OBJECTIVE: The objective was to determine the pharmacokinetics of minocycline after administration of a single oral dose in fed and fasted dogs. METHODS: Ten research hounds were administered oral minocycline (approximately 5 mg/kg) with and without food, in a crossover study, with a one-week wash-out between treatments. Blood samples were collected immediately prior to minocycline administration and over 24 h. Minocycline plasma drug concentrations were measured using high-performance liquid chromatography using ultraviolet detection and were analysed with compartmental modelling to determine primary pharmacokinetic parameters. Each dog was analysed independently, followed by calculation of means and variation of the dogs. The Wilcoxon signed-rank test [analysing secondary pharmacokinetic parameters - peak concentration (CMAX ), area under the concentration versus time curve (AUC)] was used to compare the two groups. A population pharmacokinetic modelling approach was performed using nonlinear mixed effects modelling of primary parameters for the population as fixed effects and the difference between subjects as a random effect. Covariate analysis was used to identify the source of variability in the population. RESULTS: No significant difference was found between treatments for AUC (P = 0.0645), although AUC was higher in fasted dogs. A significant difference was found for CMAX (P = 0.0059), with fasted dogs attaining a higher CMAX . The covariate of fed versus fasted accounted for a significant variation in the pharmacokinetics. CONCLUSIONS AND CLINICAL IMPORTANCE: Because feeding was a significant source of variation for the population's primary pharmacokinetic parameters and fasted dogs had higher minocycline concentrations, we recommend administering minocycline without food.

Evaluation of canine-specific minocycline and doxycycline susceptibility breakpoints for meticillin-resistant Staphylococcus pseudintermedius isolates from dogs.

BACKGROUND: Using the US Clinical and Laboratory Standards Institute (CLSI) human tetracycline breakpoints to predict minocycline and doxycycline susceptibility of Staphylococcus pseudintermedius (SP) isolates from dogs is not appropriate because they are too high to meet pharmacokinetic/pharmacodynamic data using a standard dose. New breakpoints have been approved for doxycycline and proposed for minocycline. Revised breakpoints are four dilutions lower than tetracycline breakpoints, providing a more conservative standard for classification of isolates. HYPOTHESIS/OBJECTIVES: The objectives of this study were to measure minimum inhibitory concentrations (MICs) of minocycline and doxycycline of 100 canine meticillin-resistant SP clinical isolates, compare their susceptibilities to minocycline and doxycycline based on current and revised standards, and document their tetracycline resistance genes. METHODS: E-test strips were used to determine MICs. PCR was used to identify tet genes. RESULTS: Using the human tetracycline breakpoint of MIC ≤ 4 µg/mL, 76 isolates were susceptible to minocycline and 36 isolates were susceptible to doxycycline. In contrast, using the proposed minocycline breakpoint (MIC ≤ 0.25 µg/mL) and approved doxycycline breakpoint (MIC ≤ 0.125 µg/mL), 31 isolates were susceptible to both minocycline and doxycycline. Thirty-one isolates carried no tet genes, two had tet(K) and 67 had tet(M). CONCLUSIONS AND CLINICAL IMPORTANCE: Use of the human tetracycline breakpoints misclassified 45 and five of the isolates as susceptible to minocycline and doxycycline, respectively. PCR analysis revealed that 43 and five of the isolates classified as susceptible to minocycline and doxycycline, respectively, possessed the tetracycline resistance gene, tet(M), known to confer resistance to both drugs. These results underscore the importance of utilizing the proposed minocycline and approved doxycycline canine breakpoints in place of human tetracycline breakpoints.

Retrospective study of the prevalence of keratoconjunctivitis sicca in diabetic and nondiabetic dogs after phacoemulsification.

OBJECTIVE: To evaluate the prevalence of keratoconjunctivitis sicca (KCS) in diabetic and nondiabetic dogs following phacoemulsification. PROCEDURES: Medical records were reviewed for signalment, body weight, diabetes status, and STT at the preoperative and all postoperative examinations. A clinical diagnosis of KCS was defined as a STT <15 mm/min with compatible clinical signs. Schirmer tear test values and the prevalence of KCS based on STT <15 mm/min were evaluated at 2-4, 5-8, 9-14, 15-20, and 41-52 weeks postoperatively. Size of dog (large, >10 kg; small, ≤10 kg) and STT ranges (<15 mm/min, 15-22 mm/min and >22 mm/min) were categorized for analysis of effect of body weight and STT on prevalence of KCS. RESULTS: One hundred and seventeen nondiabetic (198 eyes) and 118 diabetic dogs (228 eyes) were evaluated. KCS was diagnosed in nearly twice as many diabetics as nondiabetics (27.4% vs. 15.4%) within 2 weeks postoperatively (P = 0.0088). Percentage of eyes with KCS among all dogs decreased over time and did not differ significantly after the first postoperative visit. Diabetic small dogs were 1.7 times more likely to have KCS than nondiabetic small dogs (P = 0.0052). Preoperative STT was significantly associated with likelihood of postoperative KCS among large (P < 0.0001), but not small dogs (P = 0.0781). Among large dogs, eyes with STTs between 15 and 22 mm/min were approximately 3 times more likely to be diagnosed with KCS after surgery than those with STT >22 mm/min. CONCLUSION: The greatest risk for KCS for all dogs is during the first 2 weeks postoperatively. Populations at greatest risk for postoperative KCS are small dogs, small diabetic dogs, and large dogs with preoperative STT ≤22.

Characterization of the contributions of Hp-MMP 9 to the serum acute phase protein response of lipopolysaccharide challenged calves.

BACKGROUND: Bovine respiratory disease (BRD) is a costly feature of modern cattle production. Early and accurate detection of BRD may prove useful in the successful management of this disease. The primary objective of the study was to define the time course of covalent complexes of neutrophil, haptoglobin (Hp) and matrix metalloproteinase 9 (Hp-MMP 9) in serum after intravenous lipopolysaccharide (LPS) in comparison to traditional markers. Our hypothesis was that serum concentrations of neutrophil Hp-MMP 9 provides information distinct from traditional acute phase protein markers. To characterize the neutrophil responses to lipopolysaccharide (E. coli; O111:B4; 2.5 µg/kg body weight), nine healthy, Jersey calves (65-82 days of age; 74.5 ± 13.1 kg) were challenged and physiologic parameters, peripheral blood cell counts and serum cortisol (C), Hp-MMP 9, Hp, alpha1-acid glycoprotein (AGP), serum amyloid A (SAA) were obtained starting 24 hours before to 96 hours post-LPS challenge. RESULTS: Physiologic parameters (temperature, pulse, respiratory rate) and attitude assessed at each time point indicated that LPS challenge resulted in rapid onset of depression, tachypnea, leukopenia, neutropenia and lymphopenia within 1 hour. Serum C concentrations were significantly increased by 1 hour post-LPS. Serum Hp-MMP 9 complexes were detectable in serum by 0.5 hours and peaked at 16 h, serum total Hp remained <10 µg/mL until 8 hours post LPS infusion and were significantly greater than baseline by 12 hours post-LPS infusion. Serum amyloid A concentrations increased significantly by 8 hours post LPS. Serum concentrations of AGP increased significantly by 16 hours post LPS. Serum concentrations of Hp, SAA and AGP remained significantly greater than baseline out to 96 hours post-LPS. The total systemic exposure to traditional makers is significantly greater than from Hp-MMP 9 CONCLUSION: Using a well described model for acute phase protein responses, the data demonstrate that serum neutrophil Hp-MMP 9 complexes appear sooner and decline more rapidly than other acute phase proteins (APP). Since Hp-MMP9 is stored pre-formed, it provides information specifically addressing the LPS-induced activation of bovine neutrophils. Contributions of Hp-MMP 9 to the serum acute phase protein response may provide useful information, independent of hepatic responses, in diagnosis of acute inflammation.

In-feed use of heavy metal micronutrients in U.S. swine production systems and its role in persistence of multidrug-resistant salmonellae.

The study aimed to characterize the role of heavy metal micronutrients in swine feed in emergence of heavy-metal-tolerant and multidrug-resistant Salmonella organisms. We conducted a longitudinal study in 36 swine barns over a 2-year period. The feed and fecal levels of Cu(2+) and Zn(2+) were measured. Salmonella was isolated at early and late finishing. MICs of copper sulfate and zinc chloride were measured using agar dilution. Antimicrobial susceptibility was tested using the Kirby-Bauer method, and 283 isolates were serotyped. We amplified pcoA and czcD genes that encode Cu(2+) and Zn(2+) tolerance, respectively. Of the 283 isolates, 113 (48%) showed Cu(2+) tolerance at 24 mM and 164 (58%) showed Zn(2+) tolerance at 8 mM. In multivariate analysis, serotype and source of isolates were significantly associated with Cu(2+) tolerance (P < 0.001). Fecal isolates were more likely to be Cu(2+) tolerant than those of feed origin (odds ratio [OR], 27.0; 95% confidence interval [CI], 2.8 to 250; P = 0.0042) or environmental origin (OR, 5.8), implying the significance of gastrointestinal selective pressure. Salmonella enterica serotypes Typhimurium and Heidelberg, highly significant for public health, had higher odds of having >20 mM MICs of Cu(2+) than did "other" serotypes. More than 60% of Salmonella isolates with resistance type (R-type) AmStTeKm (32 of 53) carried pcoA; only 5% with R-type AmClStSuTe carried this gene. czcD gene carriage was significantly associated with a higher Zn(2+) MIC (P < 0.05). The odds of having a high Zn(2+) MIC (≥8 mM) were 14.66 times higher in isolates with R-type AmClStSuTe than in those with R-type AmStTeKm (P < 0.05). The findings demonstrate strong association between heavy metal tolerance and antimicrobial resistance, particularly among Salmonella serotypes important in public health.

Staphylococcus aureus shedding pattern throughout lactation in dairy cows with naturally occurring intramammary infection.

OBJECTIVE: To evaluate shedding patterns of Staphylococcus aureus, specifically the association between clonal relatedness and shedding patterns of S aureus for cows with naturally occurring S aureus intramammary infection. DESIGN: Longitudinal field study. SAMPLE: Milk samples from 22 lactating cows (29 mammary glands) of varied numbers of lactations on 2 dairies. Procedures-Foremilk samples were collected weekly for 26 to 44 weeks during lactation from individual mammary glands. Milk samples were cultured bacteriologically with a 0.01-mL inoculum. Samples were considered culture positive for S aureus if ≥ 1 colony-forming units were obtained. Milk samples from known S aureus-positive mammary glands that were culture negative for S aureus or culture positive with a single colony of S aureus were cultured bacteriologically a second time with a 0.1-mL inoculum. Longitudinal shedding patterns of S aureus and the effect of strain type on ln(colony forming unit count) were examined. RESULTS: With the 0.01-mL inoculum, 914 of 1,070 (85%) samples were culture positive. After reculturing of negative samples with a 0.1-mL inoculum, 1,011 (95%) of the samples were culture positive. There was no significant difference in the detection of S aureus between genotypic clusters when either the 0.01- or 0.1-mL inoculum was used. There was no significant difference in the amount of shedding between mammary glands infected with isolates in genotypic cluster 1 or 2. No consistent shedding patterns were identified among or within cows. There was a significant difference in mammary gland linear score and test day (composite) linear score between mammary glands infected with isolates in genotypic clusters 1 and 2. CONCLUSIONS AND CLINICAL RELEVANCE: S aureus was shed consistently in cows with naturally occurring intramammary infection in cows, and regardless of the pulsotype, variations in the amount of S aureus shedding had no significant effect on the ability to detect S aureus with a 0.1-mL inoculum.

The effect of ketoconazole on whole blood and skin ciclosporin concentrations in dogs.

BACKGROUND: Ciclosporin (CSA) is approved for the treatment of canine atopic dermatitis. Ciclosporin is metabolized by liver cytochrome P450 enzymes, a process inhibited by ketoconazole (KTZ). HYPOTHESIS/OBJECTIVES: The aims of this study were to determine skin and blood CSA concentrations when CSA was administered alone at 5.0 (Treatment 1) or 2.5 mg/kg (Treatment 2) and when CSA was administered at 2.5 mg/kg concurrently with KTZ at 5 (Treatment 3) or 2.5 mg/kg (Treatment 4). We hypothesized that skin and blood CSA concentrations in Treatment 1 would not differ from those obtained with T3 or T4. ANIMALS: In a randomized cross-over study, six healthy research dogs received each of the treatments (Treatment 1, 2, 3 and 4) once daily for 7 days. METHODS: After the first, fourth and seventh dose for each treatment, a peak and trough skin punch biopsy sample and whole blood sample were collected and analysed with high-performance liquid chromatography-tandem mass spectrometry. Data were analysed using a repeated measures approach with PROC MIXED in SAS. Pairwise comparisons were performed with least squares means and Tukey-Kramer adjustment for multiple comparisons. RESULTS: Mean blood CSA concentrations in Treatment 1 were not different from those in Treatment 2 or 4, but were less than in Treatment 3. Mean skin CSA concentrations in Treatment 1 were greater than in Treatment 2, not different from those in Treatment 4, and less than those in Treatment 3. CONCLUSIONS AND CLINICAL IMPORTANCE: Administration of CSA and KTZ concurrently at 2.5 mg/kg each may be as effective as CSA alone at 5.0 mg/kg for treatment of canine atopic dermatitis.

Yersinia enterocolitica of porcine origin: carriage of virulence genes and genotypic diversity.

Yersinia enterocolitica is an important foodborne pathogen, and pigs are recognized as a major reservoir and potential source of pathogenic strains to humans. A total of 172 Y. enterocolitica recovered from conventional and antimicrobial-free pig production systems from different geographic regions (North Carolina, Ohio, Michigan, Wisconsin, and Iowa) were investigated to determine their pathogenic significance to humans. Phenotypic and genotypic diversity of the isolates was assessed using antibiogram, serogrouping, and amplified fragment length polymorphism (AFLP). Carriage of chromosomal and plasmid-borne virulence genes were investigated using polymerase chain reaction. A total of 12 antimicrobial resistance patterns were identified. More than two-thirds (67.4%) of Y. enterocolitica were pan-susceptible, and 27.9% were resistant against ß-lactams. The most predominant serogroup was O:3 (43%), followed by O:5 (25.6%) and O:9 (4.1%). Twenty-two of 172 (12.8%) isolates were found to carry Yersinia adhesion A (yadA), a virulence gene encoded on the Yersinia virulence plasmid. Sixty-nine (40.1%) isolates were found to carry ail gene. The ystA and ystB genes were detected in 77% and 26.2% of the strains, respectively. AFLP genotyping of isolates showed wide genotypic diversity and were grouped into nine clades with an overall genotypic similarity of 66.8-99.3%. AFLP analysis revealed that isolates from the same production system showed clonal relatedness, while more than one genotype of Y. enterocolitica circulates within a farm.

Milk yield and somatic cell count during the following lactation after selective treatment of cows at dry-off.

Selective dry cow therapy (SDCT) has received increasing attention in recent years owing to global concerns over agricultural use of antimicrobial drugs and development of antimicrobial resistance. The objective of this study was to evaluate the effect of SDCT on milk yield and somatic cell count (SCC) in dairy herds in the USA. Cows in four Ohio dairy herds were categorized into two groups (low-SCC and high-SCC) at dry-off based on their SCC and clinical mastitis (CM) history during the lactation preceding the dry-off. Low-SCC cows were randomly assigned to receive or not to receive intramammary antibiotics at dry-off. Milk yield and SCC of these cows during the following lactation were compared using linear mixed effects models, adjusting for parity, calving season, stage of lactation, previous lactation milk yield and herd. Milk yield of untreated and treated low-SCC cows at dry-off did not differ significantly during the following lactation. Overall, treated low-SCC cows had 16% lower SCC (approximately 35 000 cells/ml, P = 0·0267) than the untreated cows during the following lactation; however, the effect was variable in different herds. Moreover the impact of treatment, or the lack thereof, on milk yield varied considerably between herds. The results suggested that in some herds treating all cows at dry-off may be beneficial while in other herds leaving healthy cows without antibiotic dry cow treatment has no negative impact on milk yield or milk quality (SCC), and in fact, may be beneficial. Further studies are needed to identify characteristics of herds where treating all cows routinely at dry-off may be needed for maintaining good udder health and where switching to selective treatment of cows at dry-off would be the optimal approach to achieve best results.