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.

Characterization of postoperative "fibrin web" formation after canine cataract surgery.

PURPOSE: To describe the occurrence and associated factors for "fibrin web" (FW) formation following phacoemulsification in dogs. METHODS: A retrospective review of medical records of all dogs undergoing phacoemulsification (MU-Veterinary Health Center, 2014-2018) was conducted to associate FW formation with signalment, systemic co-morbidities, cataract stage, surgeon (resident vs faculty), phacoemulsification time, IOL, and intracameral injections including viscoelastic type. Both univariate and multivariate statistical analyses were performed to evaluate associations among variables with FW formation. RESULTS: Data from 398 eyes on 201 dogs were included; 4 left eyes (4 dogs) developed presumptive endophthalmitis and were excluded from further analysis. Forty-eight eyes did not have cataract surgery. Hence, 350 eyes on 201 dogs were included in the analyses. Among these, 84 eyes (59 dogs) developed a FW. Univariate analyses showed that the odds of FW increased with age and phacoemulsification time. Additionally, FW web was associated lens type, lens brand, and viscoelastic type. Multivariate analyses showed that when comparing lens types in combination with a particular viscoelastic, viscoelastic impacted the estimated prevalence of FW formation the most. In contrast, when the data were analyzed by lens brand, lens brand impacted prevalence more than viscoelastic type. Diabetes mellitus was not associated with FW formation. CONCLUSIONS: Based on the available data, intraocular lens implantation, viscoelastic type, dog age, and phacoemulsification time were associated with FW formation. Diabetes mellitus, gender, cataract stage, surgeon, intracameral injections other than viscoeleastic, and intra- and postoperative complications were not associated with FW formation.

Whole-Genome Comparisons of Staphylococcus agnetis Isolates from Cattle and Chickens.

Staphylococcus agnetis has been previously associated with subclinical or clinically mild cases of mastitis in dairy cattle and is one of several staphylococcal species that have been isolated from the bones and blood of lame broilers. We reported that S. agnetis could be obtained frequently from bacterial chondronecrosis with osteomyelitis (BCO) lesions of lame broilers (A. Al-Rubaye et al., PLoS One 10:e0143336, 2015 [https://doi.org/10.1371/journal.pone.0143336]). A particular isolate, S. agnetis 908, can induce lameness in over 50% of exposed chickens, exceeding normal BCO incidences in broiler operations. We reported the assembly and annotation of the genome of isolate 908. To better understand the relationship between dairy cattle and broiler isolates, we assembled 11 additional genomes for S. agnetis isolates, an additional chicken BCO strain, and ten isolates from cattle milk, mammary gland secretions, or udder skin from the collection at the University of Missouri. To trace phylogenetic relationships, we constructed phylogenetic trees based on multilocus sequence typing and genome-to-genome distance comparisons. Chicken isolate 908 clustered with two of the cattle isolates, along with three isolates from chickens in Denmark and an isolate of S. agnetis we isolated from a BCO lesion on a commercial broiler farm in Arkansas. We used a number of BLAST tools to compare the chicken isolates to those from cattle and identified 98 coding sequences distinguishing isolate 908 from the cattle isolates. None of the identified genes explain the differences in host or tissue tropism. These analyses are critical to understanding how staphylococci colonize and infect different hosts and potentially how they can transition to alternative niches (bone versus dermis).IMPORTANCEStaphylococcus agnetis has been recently recognized as associated with disease in dairy cattle and meat-type chickens. The infections appear to be limited in cattle and systemic in broilers. This report details the molecular relationships between cattle and chicken isolates in order to understand how this recently recognized species infects different hosts with different disease manifestations. The data show that the chicken and cattle isolates are very closely related, but the chicken isolates all cluster together, suggesting a single jump from cattle to chickens.

Test Agreement among Biochemical Methods, Matrix-Assisted Laser Desorption Ionization-Time of Flight Mass Spectrometry, and 16S rRNA Sequencing for Identification of Microorganisms Isolated from Bovine Milk.

The objective of this prospective study was a blinded comparison of three methods for the identification of bacteria isolated on Columbia blood agar from milk samples of dairy cows. Basic biochemical testing, matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS), and 16S rRNA partial genome sequence analysis were compared for bacterial identification to the genus or species level. Milk samples submitted from a commercial dairy farm from recently calved cows or clinical mastitis cases were cultured, and 181 isolates were identified by biochemical testing, MALDI-TOF MS, and 16S rRNA sequence analysis (179 isolates; 2 isolates could not be recovered from storage). For Staphylococcus aureus and Escherichia coli, agreement was determined at the species level. For other microbes, agreement was determined at the genus level or at the group level for streptococcus-like organisms. The positive agreement among all 3 diagnostic methods was 94%, with 95% to 98% between each pair of methods. The overall (including negative agreement) agreement among all 3 methods ranged from 97% to 100%. MALDI-TOF MS is becoming more commonplace for the genus- and/or species-level identification of bacteria isolated from milk samples and, in some laboratories, has replaced conventional biochemical methods. The results of the present study suggest that when identifying pathogens at the genus or group level, conventional culture followed up with either secondary biochemical testing or MALDI-TOF MS is of practical value. For purposes of milk quality and udder health monitoring or research, any of the 3 methods is a valuable tool for genus-level identification of bacteria isolated from dairy cow milk.

Staphylococcal intramammary infection dynamics and the relationship with milk quality parameters in dairy goats over the dry period.

The objectives of this study were (1) to report the rates of new intramammary infection (IMI) and spontaneous IMI cure over the dry period in 3 dairy goat herds; (2) to evaluate the factors predicting infection dynamics over the dry period; and (3) to define milk quality parameter thresholds that predict infection dynamics over the dry period. Two consecutive udder-half milk samples were collected 10 to 14 d apart before dry-off from 288 goats in 3 herds, and 2 consecutive udder-half samples were collected 7 to 14 d apart in the following lactation, with the first sample being collected ≤10 d in milk, from 200 of the same goats. In 2 of the herds, udder-half milk samples were also collected at the same time points (n = 312 halves; 157 goats) for measurement of milk quality parameters. Standard aerobic culture of milk samples was performed for the detection of mastitis pathogens. To rule out the presence of Mycoplasma spp. IMI, milk samples were also cultured on modified Hayflick medium. Non-Mycoplasma isolates were speciated using MALDI-TOF mass spectrometry. Staphylococcal isolates, when not identified by MALDI-TOF, were speciated using partial gene sequence analysis of rpoB or tuf. When >1 sample from an udder half yielded the same species, available isolates from the first and last positive samples for that species were strain-typed using pulsed-field gel electrophoresis. Incidence of new IMI and cure rate were computed. Generalized linear mixed regression models were built to evaluate the associations between new IMI and pre-dry somatic cell score (SCS), between IMI persistence and half-level SCS, and between IMI persistence and pre-dry IMI species. Thresholds for pre-dry SCS and lactose concentration were computed to predict IMI persistence. Overall, 12.6% (48/380) of halves had a persistent IMI. Cumulative incidence of new IMI over the dry period was 13.2%, and cure rate was 52.0%. Pre-dry SCS was not associated with odds of new IMI or IMI persistence. Pre-dry IMI species was not associated with odds of persistence. Lactose concentration was not associated with odds of persistence. Regardless of culture data, the optimal pre-dry SCS threshold to detect IMI that would persist into the next lactation was 8.7, with sensitivity and specificity of 50 and 73.8%, respectively. Further studies on the effect of control measures on species-specific incidence and cure rates during the dry period are warranted.

Persistence of coagulase negative staphylococcal intramammary infections in dairy goats.

The objectives of the research described here were to describe the persistence of intramammary infections (IMI) caused by coagulase negative staphylococci (CNS) in goats using strain-typing, and to evaluate the relationship between species-specific CNS IMI and somatic cell score (SCS) at the udder-half level. Udder-half milk samples were collected from all 909 lactating goats (1817 halves; 1 blind half) in a single herd. Milk samples were cultured on Columbia blood agar, and 220 goats with at least one half yielding a single colony type CNS were enrolled for two additional half-level samplings at approximately 1-month intervals. Isolates were identified to the species level by matrix-assisted laser desorption-ionisation time-of-flight mass spectrometry or PCR amplification and partial sequencing of tuf or rpoB. An IMI was defined as persistent when ≥1 follow-up sample yielded the same species and strain as on Day 0 based on pulsed-field gel electrophoresis. A generalised mixed linear model was used to evaluate the odds of persistence as a function of CNS species. A mixed linear model was used to evaluate the relationship between IMI status on a given day and SCS. Among 192 IMI, 69.8% were persistent based on species and strain-type. Staphylococcus simulans IMI had higher odds of persistence than Staphylococcus arlettae IMI. In primiparous goats, Staphylococcus epidermidis IMI was associated with higher SCS than S. arlettae, Staphylococcus xylosus and 'other CNS' IMI. The differences detected in the present study between CNS species, with regard to persistence of IMI and association with SCS, highlight the need to study CNS at the species and strain level to understand the pathogenicity and epidemiology of CNS in goats.

Use of MALDI-TOF to characterize staphylococcal intramammary infections in dairy goats.

The most common pathogens causing intramammary infections (IMI) in dairy goats are staphylococci. Gene sequencing has been the reference method for identification of staphylococcal species, but MALDI-TOF mass spectrometry could represent a rapid and cost-effective alternative method. The objectives were to evaluate the typeability and accuracy of partial gene sequencing and MALDI-TOF for identifying staphylococci isolated from caprine milk samples, and to evaluate the relationship between staphylococcal species IMI, milk somatic cell score (SCS), and milk yield (MY). A composite (goat-level) milk sample was collected from all 940 lactating goats in a single herd. Dairy Herd Information Association test-day data for parity, days in milk, SCS, and MY were retrieved from Dairy Herd Information Association records. Milk samples were cultured on Columbia blood agar, and isolates from samples that yielded a single colony type of a presumptively identified Staphylococcus spp. were identified by PCR amplification and partial sequencing of rpoB, tuf, or 16S-rRNA, and MALDI-TOF. Mixed linear models were used to evaluate the relationship between staphylococcal IMI, SCS, and MY. The goat-level prevalence of staphylococcal IMI based on isolation of a single colony type was 24.4% (213/874). Seventeen goats had a contaminated sample. Among the remaining goats (n = 857), the most common species causing single colony-type IMI were Staphylococcus simulans (7.9%), Staphylococcus xylosus (3.5%), Staphylococcus caprae (3.6%), Staphylococcus chromogenes (2.9%), and Staphylococcus epidermidis (2.2%). The typeability of staphylococcal isolates with partial housekeeping gene sequence analysis (rpoB, complemented by tuf and 16S as needed) was 97.7%. The typeability and accuracy of MALDI-TOF were 84 and 100%, respectively. Overall, only Staphylococcus chromogenes IMI was associated with a higher SCS than goats with no growth. After adjusting for parity and stage of lactation, staphylococcal IMI status was not significantly associated with MY. For the staphylococci isolated from goats in this herd, MALDI-TOF proved an accurate method of speciation with a relatively high typeability. An association between staphylococcal IMI, SCS, and MY was not defined using goat-level data with the exception of S. chromogenes IMI, which was associated with a higher SCS than goats with no growth.

Distribution of non-aureus staphylococci species in udder quarters with low and high somatic cell count, and clinical mastitis.

The effect of non-aureus staphylococci (NAS) in bovine mammary health is controversial. Overall, NAS intramammary infections (IMI) increase somatic cell count (SCC), with an effect categorized as mild, mostly causing subclinical or mild to moderate clinical mastitis. However, based on recent studies, specific NAS may affect the udder more severely. Some of these apparent discrepancies could be attributed to the large number of species that compose the NAS group. The objectives of this study were to determine (1) the SCC of quarters infected by individual NAS species compared with NAS as a group, culture-negative, and major pathogen-infected quarters; (2) the distribution of NAS species isolated from quarters with low SCC (<200,000 cells/mL) and high SCC (≥200,000 cells/mL), and clinical mastitis; and (3) the prevalence of NAS species across quarters with low and high SCC. A total of 5,507 NAS isolates, 3,561 from low SCC quarters, 1,873 from high SCC quarters, and 73 from clinical mastitis cases, were obtained from the National Cohort of Dairy Farms of the Canadian Bovine Mastitis Research Network. Of quarters with low SCC, high SCC, or clinical mastitis, 7.6, 18.5, and 4.3% were NAS positive, respectively. The effect of NAS IMI on SCC was estimated using mixed-effect linear regression; prevalence of NAS IMI was estimated using Bayesian analyses. Mean SCC of NAS-positive quarters was 70,000 cells/mL, which was higher than culture-negative quarters (32,000 cells/mL) and lower than major pathogen-positive quarters (129,000 to 183,000 cells/mL). Compared with other NAS species, SCC was highest in quarters positive for Staphylococcus capitis, Staphylococcus gallinarum, Staphylococcus hyicus, Staphylococcus agnetis, or Staphylococcus simulans. In NAS-positive quarters, Staphylococcus xylosus (12.6%), Staphylococcus cohnii (3.1%), and Staphylococcus equorum (0.6%) were more frequently isolated from quarters with low SCC than other NAS species, whereas Staphylococcus sciuri (14%) was most frequently isolated from clinical mastitis cases. Finally, in NAS-positive quarters, Staphylococcus chromogenes, S. simulans, Staphylococcus epidermidis, and Staphylococcus haemolyticus were isolated with similar frequency from among low SCC and high SCC quarters and clinical mastitis cases. Staphylococcus chromogenes, S. simulans, S. xylosus, S. haemolyticus, S. epidermidis, S. agnetis, Staphylococcus arlettae, S. capitis, S. gallinarum, S. sciuri, and Staphylococcus warneri were more prevalent in high than in low SCC quarters. Because the NAS are a large, heterogeneous group, considering them as a single group rather than at the species, or even subspecies level, has undoubtedly contributed to apparent discrepancies among studies as to their distribution and importance in IMI and mastitis.

Prevalence of non-aureus staphylococci species causing intramammary infections in Canadian dairy herds.

Non-aureus staphylococci (NAS), the microorganisms most frequently isolated from bovine milk worldwide, are a heterogeneous group of numerous species. To establish their importance as a group, the distribution of individual species needs to be determined. In the present study, NAS intramammary infection (IMI) was defined as a milk sample containing ≥1,000 cfu/mL in pure or mixed culture that was obtained from a cohort of cows assembled by the Canadian Bovine Mastitis Research Network. Overall, 6,213 (6.3%) of 98,233 quarter-milk samples from 5,149 cows and 20,305 udder quarters were associated with an NAS IMI. Of the 6,213 phenotypically identified NAS isolates, 5,509 (89%) were stored by the Canadian Bovine Mastitis Research Network Mastitis Pathogen Collection and characterized using partial sequencing of the rpoB housekeeping gene, confirming 5,434 isolates as NAS. Prevalence of each NAS species IMI was estimated using Bayesian models, with presence of a specific NAS species as the outcome. Overall quarter-level NAS IMI prevalence was 26%. The most prevalent species causing IMI were Staphylococcus chromogenes (13%), Staphylococcus simulans (4%), Staphylococcus haemolyticus (3%), Staphylococcus xylosus (2%), and Staphylococcus epidermidis (1%). The prevalence of NAS IMI as a group was highest in first-parity heifers and was evenly distributed throughout cows in parities ≥2. The IMI prevalence of some species such as S. chromogenes, S. simulans, and S. epidermidis differed among parities. Overall prevalence of NAS IMI was 35% at calving, decreased over the next 10 d, and then gradually increased until the end of lactation. The prevalence of S. chromogenes, Staphylococcus gallinarum, Staphylococcus cohnii, and Staphylococcus capitis was highest at calving, whereas the prevalence of S. chromogenes, S. haemolyticus, S. xylosus, and S. cohnii increased during lactation. Although the overall prevalence of NAS IMI was similar across barn types, the prevalence of S. simulans, S. xylosus, S. cohnii, Staphylococcus saprophyticus, S. capitis, and Staphylococcus arlettae IMI was higher in tiestall barns; the prevalence of S. epidermidis IMI was lowest; and the prevalence of S. chromogenes and Staphylococcus sciuri IMI was highest in bedded-pack barns. Staphylococcus simulans, S. epidermidis, S. xylosus, and S. cohnii IMI were more prevalent in herds with intermediate to high bulk milk somatic cell count (BMSCC) and S. haemolyticus IMI was more prevalent in herds with high BMSCC, whereas other common NAS species IMI were equally prevalent in all 3 BMSCC categories. Distribution of NAS species IMI differed among the 4 regions of Canada. In conclusion, distribution differed considerably among NAS species IMI; therefore, accurate identification (species level) is essential for studying NAS epidemiology.

Comparison of Virulence Gene Identification, Ribosomal Spacer PCR, and Pulsed-Field Gel Electrophoresis for Typing of Staphylococcus aureus Strains Isolated from Cases of Subclinical Bovine Mastitis in the United States.

Staphylococcus aureus is one of the most important pathogens causing contagious mastitis in dairy cattle worldwide. The objectives of this study were to determine if recently described S. aureus genotype B was present among previously characterized isolates from cases of bovine intramammary infection in the United States and to compare pulsed-field gel electrophoresis (PFGE) to the combination of ribosomal spacer PCR (RS-PCR) and virulence gene identification for typing of S. aureus strains. The hypothesis was that isolates that were previously characterized as contagious would be identified as genotype B and that the results of the two strain-typing methods would be comparable. Isolates were selected from a collection of S. aureus isolates from eight dairy farms. Mammary quarter milk somatic cell count (SCC) and N-acetyl-ß-d-gluconaminidase (NAGase) activity data were known and used to evaluate strain pathogenicity. RS-PCR was performed with conventional gel electrophoresis, and PCR was used for toxin gene identification. RS-PCR patterns were associated with a specific virulence gene pattern, as previously reported. Five RS-PCR banding patterns were identified. None of the isolates were characterized as genotype B. No association between RS-PCR types and milk SCC was found; however, NAGase activity was significantly higher in milk from mammary glands infected with RS-PCR banding type 1 (RSP type 1) than in milk from those infected with RSP type 2. The discriminatory power values were 1.0 and 0.46 for PFGE and RS-PCR, respectively. These data suggest that genotype B may have a limited geographic distribution and that PFGE is more discriminatory than RS-PCR performed with conventional gel electrophoresis for typing of S. aureus isolates of bovine origin.

Evaluation of a Permanent Synthetic Osteochondral Implant in the Equine Medial Femoral Condyle.

OBJECTIVE: To evaluate bone ingrowth, integration, and tolerance of a synthetic osteochondral implant in the medial femoral condyle (MFC) of normal horses. STUDY DESIGN: Experimental study. ANIMALS: Adult horses (n = 6). METHODS: Horses were anesthetized and bilateral femorotibial arthrotomies were performed for placement of 1 implant consisting of polycarbonate urethane with a titanium base in 1 MFC. The contralateral MFC served as a sham-operated control without reaming of cartilage or subchondral bone. Lameness evaluations and radiographs were performed pre-operatively with subsequent monthly lameness exams and radiographs at 6 months. Synovial fluid was collected for analysis from the adjacent femoropatellar joints pre-operatively and at several intervals post-operatively. Horses were euthanatized 6 months post-operatively. Stifles were harvested for gross and histologic evaluations. RESULTS: Two horses were never lame, 2 were mildly lame, and 1 exhibited moderate lameness. Synovial fluid inflammatory parameters of the adjacent femoropatellar joints were not significantly different. No significant changes occurred radiographically over time in either stifle. Histologic assessment of synovium from the medial femorotibial joint revealed no differences in inflammatory changes between implant and sham stifles. Integration and osteoconductivity of the implant were graded as good in 4 and 3 of 5 specimens, respectively. Complications included joint sepsis resulting in euthanasia (1 horse), persistent lameness (1 horse), incisional seromas (4 horses), and incisional dehiscence (2 horses). CONCLUSION: Results of this pilot study indicate that the implant was compatible with placement in the MFC of normal horses. Implant design allowed bone ingrowth within the titanium base and provision of a synthetic articular surface.

Subchronic Oral Toxicity of Sodium Tungstate in Sprague-Dawley Rats.

The subchronic toxicity of sodium tungstate dihydrate aqueous solution in male and female Sprague-Dawley rats was evaluated by daily oral gavage of 0, 10, 75, 125, or 200 mg/kg/d for 90 days. Measured parameters included food consumption, body weight measurements, hematology, clinical chemistry, and histopathological changes. There was a significant decrease in food consumption and body weight gain in males at 200 mg/kg/d from days 77 to 90; however, there was no effect in food consumption and body weights in females. There were no changes in the hematological and clinical parameters studied. Histopathological changes were seen in kidney of male and female and epididymis of male rats. Histopathological changes were observed in the kidneys of male and female rats dosed at 125 or 200 mg/k/d consisting of mild to severe cortical tubule basophilia in 2 high-dose groups. Histological changes in epididymides included intraluminal hypospermia with cell debris in the 200 mg/kg/d dosed male rats. Histopathological changes were observed in the glandular stomach including inflammation and metaplasia in the high-dose groups (125 or 200 mg/kg/d) of both sexes of rats. Based on histopathology effects seen in the kidneys, the lowest observable adverse effect level was 125 mg/kg/d and the no observable adverse effect level was 75 mg/kg/d in both sexes of rats for oral subchronic toxicity.

The National Mastitis Council: A Global Organization for Mastitis Control and Milk Quality, 50 Years and Beyond.

The National Mastitis Council was founded in 1961 based on the desire of a forward-thinking group of individuals to bring together "all forces of organized agriculture in the United States to combat, through every practical device, the mastitis threat to the Nation's health and food safety". What started as a small organization focused on mastitis of dairy cattle in the United States has grown into a global organization for mastitis and milk quality. Over the last 50-plus years the concerted efforts of the membership have led to the synthesis and dissemination of a considerable body of knowledge regarding udder health, milk quality, and food safety which has improved dairy cattle health and well-being and farm productivity.

Surgical correction of congenital entropion in related Boer goat kids using a combination Hotz-Celsus and lateral eyelid wedge resection procedure.

Five related Boer goat kids (≤4 months of age) were presented to the University of Missouri, Veterinary Teaching Hospital (MU-VMTH) with epiphora and blepharospasm of several weeks duration and commencing prior to 1 month of age in all animals. Clinical examination confirmed euryblepharon and entropion bilaterally in two females and one male and unilaterally in two female kids. Deep stromal corneal ulceration was present in two eyes, and corneal granulation tissue and fibrosis were present in half (5/10) the affected eyes. A combination Hotz-Celsus and lateral eyelid wedge resection procedure was performed on all affected eyelids. Recheck examinations and long-term follow-up confirmed resolution of the entropion, preservation of normal eyelid conformation, and restoration of ocular comfort. Pedigree analysis ruled out sex-linked and autosomal dominant inheritance patterns; a specific mode of inheritance could not be determined. The Boer goat breed may be at increased risk for the development of entropion. This cases series represents the first report of entropion in the caprine species.

Otitis interna, media, and externa with destruction of the left tympanic bulla and subluxation and septic arthritis of the left temporomandibular joint in an alpaca (Vicugna pacos).

A 1.5-year-old, 37.7 kg, female alpaca was evaluated for a 2-week history of weight loss, left ear droop, and deviation of the rostral mandible to the right. Antemortem radiography and postmortem examination revealed otitis interna, media, and externa, destruction of the left tympanic bulla, and subluxation and septic arthritis of the left temporomandibular joint.

Otite interne, moyenne et externe avec destruction de la bulle tympanique gauche et subluxation et arthrite septique de l'articulation temporomandibulaire gauche chez un alpaga(Vicugna pacos) . Une femelle alpaga âgée de 1,5 an, pesant 37,7 kg, a été évaluée pour une anamnèse de 2 semaines de perte de poids, d'oreille gauche pendante et de déviation de la mandibule rostrale à la droite. Une radiographie avant le décès et une nécropsie ont révélé une otite interne, moyenne et externe, la destruction de la bulle tympanique gauche ainsi qu'une subluxation et l'arthrite septique de l'articulation temporomandibulaire gauche.(Traduit par Isabelle Vallières).

Current and Emerging Diagnostic Approaches to Bacterial Diseases of Ruminants.

The diagnostic approaches and methods to detect bacterial pathogens in ruminants are discussed, with a focus on cattle. Conventional diagnostic methods using culture, isolation, and characterization are being replaced or supplemented with new methods. These include molecular diagnostics such as real-time polymerase chain reaction and whole-genome sequencing. In addition, methods such as matrix-assisted laser desorption ionization-time-of-flight mass spectrometry enable rapid identification and enhanced pathogen characterization. These emerging diagnostic tools can greatly enhance the ability to detect and characterize pathogens, but performance and interpretation vary greatly across sample and pathogen types, disease syndromes, assay performance, and other factors.

Comparison of incisional gastropexy with and without addition of two full-thickness stomach to body wall sutures.

OBJECTIVE: To compare complications between a modified incisional gastropexy (MIG) technique and standard incisional gastropexy (SIG). ANIMALS: 347 client-owned dogs. PROCEDURES: Dogs that had undergone SIG or MIG from March 2005 through April 2019 were identified through a medical record search of the University of Missouri Veterinary Health Center. The MIG technique is identical to SIG except 2 additional simple interrupted sutures are added, 1 cranial and 1 caudal to the continuous suture line, going full thickness into the stomach to ensure engagement of submucosa. Medical record information was used to identify intraoperative, postoperative, and short-term complications, and telephone or email communication to pet owners and/or referring veterinarians was used to identify complications (short-term and long-term) after discontinuance of care at the University of Missouri Veterinary Health Center. Intraoperative, postoperative, short-term, and long-term complications were analyzed in aggregate within 6 matched groupings: (1) gastropexy for gastric dilatation-volvulus, (2) prophylactic gastropexy without other procedures, (3) gastropexy with ovariohysterectomy, (4) gastropexy with castration, (5) gastropexy with splenectomy, and (6) gastropexy with celiotomy other than splenectomy. Overall rates of complications potentially attributed to gastropexy were compared between SIG and MIG using the Fisher exact test. Overall rates of complications not attributed to gastropexy were compared between SIG and MIG using the χ2 test. RESULTS: There were no significant differences in overall complication rates between SIG and MIG. CLINICAL RELEVANCE: Surgeons who feel that engagement of gastric submucosa is important for gastropexy success may use the MIG technique with minimal fear of complications. However, superiority of one technique over the other cannot be determined on the basis of this study.

Bacterial culture and susceptibility of samples taken from septic foot lesions of adult beef cattle.

BACKGROUND: Lameness is an economically important and common disease of cattle, and foot disease is the most common cause of lameness in cattle. Limited data is available regarding lameness in cow-calf operations. OBJECTIVES: Describe the bacteria most commonly isolated from septic lesions of the feet of adult beef cattle and the antimicrobial susceptibility patterns of the isolated bacteria. ANIMALS: Fifty-four adult cattle from cow-calf operations and diagnosed with a sole abscess or distal interphalangeal joint sepsis were enrolled. METHODS: Prospective observational study. Abscess fluid from a convenience sample of clinical cases was cultured. Isolated bacteria were identified using matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) mass spectrometry or 16s rRNA gene sequencing. Antimicrobial susceptibility profiling was performed on isolates when a bacterial species was identified from ≥5 samples. RESULTS: Fifty of the 54 samples were polymicrobial. Trueperella pyogenes (22/54), Streptococcus uberis (16/54), and Bacteroides pyogenes (14/54) were the most commonly isolated bacteria. Eighty-one of 96 tested isolates were resistant to at least 1 antimicrobial; multidrug resistance was identified in 37/96 isolates. Oxytetracycline (50/96), tylosin (40/96), and florfenicol (37/96) resistance was commonly identified. Resistance to ceftiofur (5/96) was rare. CONCLUSIONS AND CLINICAL IMPORTANCE: Septic processes of the foot in these adult beef cattle frequently were polymicrobial. Most of the isolated bacteria were resistant to at least 1 antimicrobial with over one-third being multidrug resistant. Although simple sole abscesses do not require antimicrobial treatment, deep septic processes of the foot often are treated with antimicrobials. Culture and susceptibility of deep septic lesions may guide judicious antimicrobial usage.