ABSTRACT Background Phenazopyridine is used for ancillary pain management in the treatment of goats with obstructive urolithiasis. However, there are no published studies on the pharmacokinetics, safety, or efficacy of phenazopyridine in goats. Hypothesis/Objectives Determine the pharmacokinetic parameters of phenazopyridine after oral administration in goats with obstructive urolithiasis after tube cystostomy surgery. Animals Six male goats, ages 3 months to 4 years. Methods Prospective, observational study. Goats presenting to a veterinary institution diagnosed with obstructive urolithiasis underwent a tube cystostomy surgery. After surgery, phenazopyridine (4 mg/kg PO q12h) was administered. Plasma and urine samples were collected at predetermined intervals, and the concentration of phenazopyridine and clinically relevant metabolites was determined using ultra high‐performance liquid chromatography with mass spectrometry. The pharmacokinetic parameters were determined using non‐compartmental analysis. Results The harmonic mean terminal elimination plasma half‐life (T1/2), geometric mean maximum plasma concentration (Cmax), and area under the curve (AUC) were 0.5 h (0.22–1.57 h), 263.4 ng/mL (137.35–1047.88 ng/mL), and 0.69 h*ng/mL (0.10–2.99 h*ng/mL), respectively for phenazopyridine. The concentration of phenazopyridine in urine samples was below the limit of assay detection (1.5 ng/mL) in all but one sample. Conclusions and Clinical Importance Phenazopyridine was rapidly eliminated from plasma and did not concentrate at detectable levels in the urine after oral administration.

Mastitis is the most burdensome concern for the dairy cattle industry. Antimicrobials are often prophylactically administered to dairy cows at dry-off to reduce the risk of intramammary infection during the dry period and subsequent lactation. Mastitis incidence has increased in dairy heifers after calving, leading to extralabel drug use of various dry cow products, including intramammary ceftiofur hydrochloride. However, the pharmacokinetics and efficacy of this application have yet to be studied. This study aimed to compare the pharmacokinetics and efficacy following no treatment, a non-antimicrobial teat sealant, or a single dose of intramammary ceftiofur given at 21 or 14 days before expected calving. We hypothesized that milk collected following dosing would contain drug residues below the FDA tolerance of 100 ng/mL by calving, and heifers within the ceftiofur treatment groups would have lower somatic cell counts (SCCs) than heifers in the teat sealant and nontreatment control groups. Following treatment or no treatment of 24 prepartum heifers, milk samples were collected until 21 days after calving. Somatic cell counts and ceftiofur concentrations were assessed utilizing a cell counter and UPLC/MS detection, respectively. Ceftiofur administration did not significantly reduce SCCs compared to other groups by days 7, 14, or 21. For heifers treated 14 and 21 days prior to calving, milk had a maximum ceftiofur concentration of 8.14 ± 6.24 and 4.20 ± 5.07 ng/mL 48 h into lactation, respectively. The minimal ceftiofur concentrations in milk collected from these heifers indicate that administration of ceftiofur 14 or 21 days before calving is unlikely to lead to violative residues. However, it is essential that regional regulations regarding the use of ceftiofur are adhered to.

Prophylactic and perioperative use of antibiotics is common prior to abdominal surgery in cattle for minimizing the risk of postoperative infections. Yet, there is little information on drug concentrations at sites of potential infections following surgical procedures. The objective of this study was to compare the concentrations in the plasma, peritoneal fluid, and interstitial fluid of ampicillin trihydrate in cattle. In a randomized design, ampicillin trihydrate, a β-lactam antibiotic, was administered to 12 healthy Holstein-Friesian steers intraoperatively via intraperitoneal (IP; n = 6) or intramuscular (IM; n = 6) injection in the cervical neck muscles at 11 mg/kg for both groups. For IP administration, ampicillin trihydrate was deposited into the abdominal cavity following an incision in the right paralumbar fossa. Steers in the IM group were administered ampicillin prior to surgical closure. Peritoneal fluid and interstitial fluid were collected using ultrafiltration probes. IP administration achieved higher concentrations in peritoneal fluid as compared to IM administration. Maximum plasma concentrations were significantly higher following IP administration (3.11 ± 2.5 μg/mL; p < 0.004) compared to the IM group (0.05 ± 10.9 μg/mL). Despite high peritoneal fluid concentrations of ampicillin, the variability in critical pharmacokinetic parameters following IP administration raises concerns about its therapeutic reliability. The correlation between intraperitoneal drug concentrations and clinical efficacy warrants further investigation.

Abstract Background Bovine respiratory disease (BRD) is an economically important disease in the beef industry, and a major driver of therapeutic antibiotic use. Pharmacokinetic data of these drugs is relatively limited in diseased animals. Hypothesis/Objective To determine the concentrations of pradofloxacin, florfenicol, and tulathromycin in the airways, plasma, and interstitial fluid (ISF) of steers with a clinically relevant model of bacterial respiratory disease. Animals Twenty‐four Holstein and Holstein/Jersey cross steers ranging in age from 6 to 15 months. Methods A randomized, blinded clinical trial was performed. After transport stress, steers were inoculated with Mannheimia hemolytica to induce BRD. Upon onset of clinical disease, steers were treated with pradofloxacin, florfenicol or tulathromycin. Blood, ISF, and pulmonary epithelial lining fluid (PELF) samples were obtained for drug concentration determination. Clinical exams and thoracic ultrasound examinations were conducted daily. Animals were euthanized at the end of the study period to assess lung lesions. Results Pradofloxacin Cmax in PELF was 0.81 μg/mL (CV = 49.02%) and penetration into the PELF was 203.58% (72%). Florfenicol Cmax in PELF was 2.94 μg/mL (42.1%) and penetration was 230.08% (78.82%). Tulathromycin PELF Cmax was 0.9 μg/mL (45.03%) and PELF penetration was 518.97% (56.59%). Conclusions and Clinical Importance There are differences in penetration of the drugs into the ISF and PELF compared to one another and previous data from healthy steers demonstrating the effect of disease on the PK of these drugs.

Peripheral vasoconstriction is a major consequence of fescue toxicosis (FT). However, it remains unclear if major blood vessels, such as the pulmonary artery, are impacted by this disease. This study aimed to evaluate changes in pulmonary arterial pressure (PAP) and different physiological parameters in replacement beef heifers consuming an endophyte-infected (EI) ration. Purebred Angus heifers (216.3 ± 6.1 kg; 9 to 11 mo of age; n = 36) were randomly separated and fed either an EI or endophyte-free (EF) total mixed ration for 49 d. On day 1, iButton temperature data loggers were inserted intravaginally to record temperature every 20 min throughout the entire study. The cattle comfort index (CCI) was used to assess comfort and define exposure to heat stress as thermoneutral, mild heat stress (MILD-HS), or moderate heat stress (MOD-HS). PAP was measured every 20 d to assess its response to ergot alkaloid and heat stress exposure. Weekly measurements were recorded to monitor growth and physiological responses of both treatment groups. Data were analyzed using the MIXED procedure of SAS with repeated measures. Both groups were exposed to MILD- and MOD-HS on several occasions. An interaction between PAP results and heat stress exposure was identified, as both groups reported increased PAP values as CCI values decreased. The EF heifers ended the study with greater body weight (P < 0.05), average daily weight gain (P < 0.01), body condition score (P < 0.01), and lower hair shedding score (P < 0.01) than EI heifers. In contrast, EI heifers maintained greater vaginal temperatures throughout the study (P < 0.01). Additionally, EI heifers reported lower caudal artery diameters (P < 0.01) than the EF heifers, but no differences were observed in caudal vein diameters (P > 0.05). Lastly, no differences were observed in the packed cell volume and prolactin concentrations (P > 0.05). While the EI group displayed classical symptoms of FT, including caudal artery vasoconstriction, the PAP results indicate that ergot alkaloid consumption does not induce vasoconstriction on the pulmonary artery, but rather reflect that PAP may be altered by the exposure to heat stress. Additional research should be conducted in regions where changes in PAP are of interest to fully understand the effects of heat stress exposure on the cardiopulmonary system of cattle. Moreover, future investigations in EI fescue-dominant environments should focus on developing strategies to mitigate the negative consequences of FT and heat stress, in order to enhance animal welfare, productivity, and profitability in the beef industry.

Objective:The study objectives were to calculate the apparent efficiency of immunoglobulin G (IgG) absorption in beef calves receiving complete colostrum replacement and to compare the effects of 3 colostrum replacement strategies on the apparent efficiency of IgG absorption (AEA), transfer of passive immunity (TPI), morbidity, mortality, and average daily gain (ADG). Methods:45 newborn beef calves were randomly assigned to 1 of 3 colostrum interventions. Group A received approximately 170 g of IgG via colostrum replacer after birth. Group B received approximately 250 g of IgG in 2 feedings within 6 to 8 hours. Group C received approximately 250 g of IgG in 3 feedings within 12 to 14 hours. Serum IgG concentrations were determined at 0, 6, 12, and 24 hours. Transfer of passive immunity, AEA, and ADG were compared among intervention groups. Transfer of passive immunity, morbidity, mortality, and ADG were also compared to 15 control calves left with their dams for natural nursing. Results:Median AEA for groups A, B, and C at approximately 24 hours was 36.2%, 26.3%, and 23.9%, respectively, with no significant differences among groups when accounting for other covariates. Average serum IgG concentration and the proportion of calves with failed TPI (IgG < 10 g/L) and adequate TPI (IgG ≥ 24 g/L) was not statistically different among intervention and control groups. Morbidity, mortality, and ADG until weaning was similar among all groups. Conclusions:AEA in beef calves was lower than that reported in dairy calves. All colostrum replacement strategies prevented failed TPI. There was no difference in health and growth outcomes between intervention and control groups. Clinical Relevance:While timely feeding of ≥ 170 g of IgG prevented failed TPI in beef calves, ≥ 250 g of IgG may be necessary to achieve adequate TPI. Producers and veterinarians should not hesitate to intervene to ensure timely colostrum ingestion.

OBJECTIVE:To determine the feasibility of catheterizing the portal vein to obtain serial portal vein blood samples in steers. We hypothesized that the portal vein catheterization would be a successful continuous sampling technique with minimal adverse effects in steers. METHODS:2 groups of steers were used: a pilot group (n = 2) and experimental group (n = 6). In both groups, steers were sedated with xylazine. The right rib spaces were clipped and aseptically prepped. The portal vein was visualized via ultrasound, and a 14-gauge catheter was placed percutaneously and advanced into the portal vein. A guide wire was passed through the catheter, followed by a tissue dilator and then a vascular balloon catheter. In the pilot group, blood chemistries were performed prior to portal vein catheterization and then again once the catheter was placed (with samples from both the jugular vein and portal catheter). The liver was also examined at necropsy for any gross lesions in both groups. RESULTS:All steers tolerated the portal vein catheters well, with the catheters lasting for the full length of the study period (7 days). The only observed adverse reaction was a superficial abscess at the catheter site (n = 3). On necropsy, 1 liver had gross discoloration, but no other abnormalities were noted. There were no significant changes in biochemistry profiles before or after portal vein catheterization. CONCLUSIONS:Portal vein catheterization is a novel and feasible serial sampling technique of the portal vein. CLINICAL RELEVANCE:This technique can be used in future pharmacokinetic, nutrition, metabolism, or toxicity studies.

The food animal sector’s use of antimicrobials is heavily critiqued for its role in allowing resistance to develop against critically important antimicrobials in human health. The WHO recommends using lower tier antimicrobials such as florfenicol for disease treatment. The primary objective of this study was to assess the differences in resistance profiles of enteric microbes following administration of florfenicol to steers using both FDA-approved dosing regimens and two different detection methods. Our hypothesis was that we would identify an increased prevalence of resistance in the steers administered the repeated, lower dose of florfenicol; additionally, we hypothesized resistance profiles would be similar between both detection methods. Twelve steers were administered either two intramuscular (20 mg/kg q 48 h; n = 6) or a single subcutaneous dose (40 mg/kg, n = 6). Fecal samples were collected for 38 days, and E. coli and Enterococcus were isolated and tested for resistance. Fecal samples were submitted for metagenomic sequencing analysis. Metagenomics revealed genes conferring resistance to aminoglycosides as the most abundant drug class. Most multidrug resistance genes contained phenicols. The genotypic and phenotypic patterns of resistance were not similar between drug classes. Observed increases in resistant isolates and relative abundance of resistance genes peaked after drug administration and returned to baseline by the end of the sampling period. The use of a “lower tier” antimicrobial, such as florfenicol, may cause an increased amount of resistance to critically important antimicrobials for a brief period, but these changes largely resolve by the end of the drug withdrawal period.

AbstractThe use of antimicrobial drugs in food-producing animals contributes to the selection pressure on pathogenic and commensal bacteria to become resistant. This study aims to evaluate the existence of trade-offs between treatment effectiveness, cost, and the dynamics of resistance in gut commensal bacteria. We developed a within-host ordinary differential equation model to track the dynamics of antimicrobial drug concentrations and bacterial populations in the site of infection (lung) and the gut. The model was parameterized to represent enrofloxacin treatment for bovine respiratory disease (BRD) caused by Pastereulla multocida in cattle. Three approved enrofloxacin dosing regimens were compared for their effects on resistance on P. multocida and commensal E. coli: 12.5 mg/kg and 7.5 mg/kg as a single dose, and 5 mg/kg as three doses. Additionally, we explored non-FDA-approved regimes. Our results indicated that both 12.5 mg/kg and 7.5 mg/kg as a single dose scenario increased the most the treatment costs and prevalence of P. multocida resistance in the lungs, while 5 mg/kg as three doses increased resistance in commensal E. coli bacteria in the gut the most out of the approved scenarios. A proposed non-FDA-approved scenario (7.5 mg/kg, two doses 24 h apart) showed low economic costs, minimal P. multocida, and moderate effects on resistant E. coli. Overall, the scenarios that decrease P. multocida, including resistant P. multocida did not coincide with those that decrease resistant E. coli the most, suggesting a trade-off between both outcomes. The sensitivity analysis suggests that bacterial populations were the most sensitive to drug conversion factors into plasma ($${\beta}$$ β ), elimination of the drug from the colon ($$\vartheta$$ ϑ ), fifty percent sensitive bacteria (P. multocida) killing effect ($${\text{L}}_{\text{s50}}$$ L s50 ), fifty percent of bacteria (E. coli) above ECOFF killing effect ($${\text{C}}_{\text{r50}}$$ C r50 ), and net drug transfer rate in the lung ($$\gamma$$ γ ) parameters.

Parasitic infections in dairy cattle reduce herd immunity, milk production, and conception rates. This leads to higher production costs, compromised animal welfare, and increased interest in extralabel drug use. The extralabel use of anthelmintics poses food safety risks for consumers since appropriate withdrawal intervals in milk have yet to be established. Although topical eprinomectin has no milk withdrawal time, more research is needed to determine the residues present in milk after subcutaneous administration. This study aimed to characterize the pharmacokinetics of injectable eprinomectin in dry dairy cows. We hypothesized that, when given at the labeled dose, eprinomectin residues in dry dairy cattle would be below the FDA milk tolerance at the onset of lactation. Plasma was collected daily from 13 mature dairy cattle for 7 days postadministration, followed by periodic samples for 90 days. After calving, milk was collected daily until 90 days. Eprinomectin concentrations were measured using HPLC-fluorescence detection. The maximum eprinomectin concentration in plasma and milk was approximately 36 ng/mL 43 h after administration and 3 ng/mL at the onset of lactation, respectively. The low eprinomectin levels in milk collected from these lactating dairy cattle suggest that administering eprinomectin at dry-off is unlikely to result in violative residues. However, subcutaneous eprinomectin in lactating dairy cattle would be hard to justify unless there is evidence that the approved topical formulation is clinically ineffective.

AbstractBackgroundPharmacological activity of intramammary drugs depends on adequate drug concentrations within the cistern, but sampling is often limited. Insight into the active drug concentration within the mammary cistern may assist in determining effective and appropriate therapeutic decisions for cows being treated for mastitis.ObjectiveEvaluate the disposition of ceftiofur hydrochloride administered intramammary in diseased and nondiseased quarters. Whole milk and ultrafiltrate sampling techniques were compared.AnimalsTen mature, late lactation Holstein (n = 9) and Jersey (n = 1) dairy cows (422‐670 kg) with naturally occurring clinical mastitis, producing between 1.4 and 15.9 kg/day of milk.MethodsUltrafiltration probes were placed in both mastitic and healthy quarters. Each quarter was treated with 2 doses of 125 mg ceftiofur hydrochloride suspension, and whole milk and milk ultrafiltrate samples were collected. Ceftiofur concentrations in composite whole milk and milk ultrafiltrate were analyzed.ResultsThe maximum concentration of ceftiofur was higher in ultrafiltrate samples, but no differences were identified in healthy or mastitic quarters. The use of ultrafiltration probes provides a novel technique for free drug concentrations within the mastitic and healthy bovine mammary gland.Conclusions and Clinical ImportanceSignificant inter‐ and intracow variability and lower daily milk weights may overestimate ceftiofur concentrations available within the cistern. The pharmacokinetic (PK) parameters reported in milk ultrafiltrate will help establish a link between the PK and the corresponding drug effect, potentially providing a meaningful rationale for the selection of a safe and effective dose in cows with mastitis.

Abstract Ergot alkaloid consumption is detrimental to cattle as it negatively impacts several physiological and performance parameters. The objective of this study was to evaluate changes in nutritional intake and different physiological and performance parameters of heifers consuming an ergot alkaloid-infected ration. Purebred Angus heifers (216.3 ± 6.1 kg; 9 to 11 mo of age; n = 36) were randomly separated and fed either an endophyte-infected (EI) or endophyte-free (EF) total mixed ration (TMR) for 49 d. On d 1, iButton temperature data loggers were inserted intravaginally to record temperature on a 20-min frequency throughout the entire study. Individual feed and water intake was measured utilizing the Vytelle Sense system. Hourly environmental temperature and relative humidity measurements were utilized to calculate the temperature-humidity index (THI) and define exposure to heat stress as Thermoneutral (NO-HS), Mild (MILD-HS) and Moderate (MOD-HS). Pulmonary arterial pressure (PAP) was measured every 20 d to assess its response to ergot alkaloid and heat stress exposure. Additionally, weekly measurements were collected to monitor growth and physiological responses to EI-TMR intake. Data were analyzed using a MIXED procedure of SAS with repeated measures. The effects of treatment, day, THI and its interactions were evaluated for body weight (BW), average daily gain (ADG), body condition score (BCS), hair shedding score (HSS), vaginal temperature (VT), feed intake (FI), water intake (WI) and PAP. EF heifers had significantly less HSS and greater BW, ADG, and BCS than EI heifers over time (P < 0.0001). EF heifers also had lower VT than EI heifers (39.5 ± 0.1 vs 40.1 ± 0.1° C; P < 0.0001) and had reduced daily WI (8.3 ± 0.4 vs 9.4 ± 0.4 L; P < 0.0001). Moreover, WI was also found to be positively correlated to THI, as both EF and EI groups significantly increased (P < 0.0001) their WI as THI increased from NO-HS (5.9 ± 0.6 vs 7.4 ± 0.6 L) to MILD-HS (9.4 ± 0.6 vs 10.8 ± 0.6 L) and MOD-HS (12.8 ± 0.6 vs 13.4 ± 0.6 L). EF heifers also had greater daily FI than EI heifers (18.8 ± 0.6 vs 12.9 ± 0.6 kg; P < 0.0001), and FI was also affected by THI as intake in both EF and EI groups decreased when transitioning from NO-HS (21.3 ± 0.6 vs 14.6 ± 0.6 kg) to MILD-HS (16.4 ± 0.6 vs 11.1 ± 0.6 kg; P < 0.0001). PAP results tended to differ between groups (29.6 ± 0.6 vs 31.1 ± 0.6 mm Hg; P = 0.0954) and increased in both EF and EI groups when transitioning from MILD-HS (27.2 ± 0.9 vs 26.2 ± 0.9 mm Hg) to NO-HS (34.8 ± 0.9 vs 36.4 ± 0.9 mm Hg; P = 0.0147). Based on these data, exposure to ergot alkaloids negatively affects animal performance as it decreases ADG, BCS and increases HSS and VT, and it also increases daily WI and reduces daily FI. Furthermore, PAP, WI and FI were also negatively impacted by changes in THI and exposure to heat stress. Additional research is necessary to understand the interactions between these variables to identify efficiency parameters.

Vasoconstriction of peripheral blood vessels is one of the hallmark symptoms of fescue toxicosis in cattle. Thus, it was hypothesized that exposure to ergot alkaloids would increase the pulmonary arterial pressure (PAP). The objectives of this study were to examine the relationship between PAP and different physiological parameters of cows grazing either endophyte-infected (EI) or novel-endophyte (EN) fescue, then evaluate changes in PAP and other physiological measurements in cows exposed to EI pastures and deemed as susceptible or tolerant based on animal performance. Pregnant Angus cows at 2 different locations grazed either EI or EN fescue pastures for 14 consecutive weeks starting in early April of 2022. Forage measurements were collected to assess ergot alkaloid exposure throughout the study. In addition to measuring PAP, weekly measurements and blood samples were collected to evaluate physiological responses to ergot alkaloid consumption. The Fescue Toxicosis Selection Method (FTSM) was used for a post hoc analysis to identify cattle as either tolerant (EI-TOL) or susceptible (EI-SUS) when challenged with ergot alkaloid exposure. Data were analyzed using a MIXED procedure of SAS with repeated measures. Cows grazing on EN pastures had greater mean PAP values than EI cows, (P < 0.01), whereas a location effect was identified when comparing both EI-TOL and EI-SUS groups (P < 0.01). Cows exposed to EN pastures had greater average daily gain (ADG) (P = 0.04) and progesterone (P4) concentrations (P < 0.01), and lower hair shedding scores (HSS; P < 0.01) than EI cows. The EI-TOL cows tended to have greater final body weight, ADG and had lower HSS (P < 0.01) than EI-SUS cows. While cattle consuming EI tall fescue exhibited classical physiological changes, the decrease in PAP of cattle consuming EI fescue was unexpected and contradicted the initial hypothesis. Furthermore, the FTSM provides a means to identify animals with superior performance in spite of the chronic exposure to ergot alkaloids. Continued investigations examining the interaction between ergot alkaloid exposure and cardiovascular parameters will lead to a fuller understanding of the disease and are pivotal for developing innovative strategies that enhance best management practices to help guarantee the sustainability of the U.S. beef industry.

Abstract Background Symmetric dimethylarginine (SDMA), a sensitive biomarker for detecting renal injury, has not been characterized in goats. Obstructive urolithiasis (OU) is the most common urinary tract disease in male small ruminants. Hypothesis/Objective Establish an SDMA reference interval (RI) in healthy adult goats and describe SDMA concentrations in goats with OU. We hypothesize that the SDMA RI in healthy adult goats will be similar to that of other adult veterinary species and that SDMA can be utilized to assess the renal function of goats experiencing OU. Animals Fifty‐five healthy adult male and female goats from a university herd were enrolled for SDMA RI development. Twenty male and female goats from a university herd were enrolled for validation of the SDMA RI established. Thirteen male goats diagnosed with OU were enrolled. Methods Clinical trial. Serum samples for all animals enrolled were collected and analyzed for SDMA using an immunoassay (IDEXX Laboratories, Inc); goats with OU had additional blood work analyzed (PCV, total solids, and serum biochemistry). Symmetric dimethylarginine and other values in goats with OU were analyzed and compared at specific time points. Results The SDMA RI for healthy, adult goats is 8.03 μg/dL (90% CI 4.81‐11.04) to 25.93 μg/dL (90% CI 22.88‐28.97). There was no correlation identified between serum creatinine and SDMA in goats with OU. Conclusions and Clinical Importance The SDMA RI for adult goats is higher than in other adult large animal species. Use of SDMA in goats with OU is not useful in assessing their renal function.

Abstract Two sheep presented with acute tonic‐clonic seizures, opisthotonos, absent pupillary light reflexes and abnormal vital signs within 18 hours after observed consumption of leaves from an ornamental shrub later identified as wintersweet (Chimonanthus praecox). Despite symptomatic treatment, both sheep died. Three other sheep that consumed the plant died after displaying similar clinical signs, resulting in 2 deaths the prior evening and 1 recovery the next morning. Gross necropsy and histologic findings were diagnostically inconclusive. Rumen contents tested positive for the alkaloid calycanthine, a centrally‐acting convulsant known to be present in wintersweet. Case reports of calycanthine toxicity in ruminants are limited, with no detailed reports published in the United States. Calycanthine has been isolated from the seeds, flowers, and leaves of the plant. Wintersweet is part of the family Calycanthaceae that including 3 species native to North America, all of which pose a neurologic risk to ruminants if consumed.

Fescue toxicosis negatively impacts cattle productivity. Previous data from our laboratory has demonstrated that cattle within a herd respond differently when grazing tall fescue, thus variation within a breed may provide genetic tolerance to the negative effects on performance. Fescue toxicosis results in major impacts on the cardiovascular system, thus it was hypothesized that exposure to ergot alkaloids negatively impacts pulmonary arterial pressure (PAP). The objective of this study was to examine changes in PAP and other production parameters in cattle consuming endophyte-infected tall fescue. Pregnant Angus cows (2 to 4 years; n = 65) were randomly divided to graze either endophyte-infected (EI) or novel endophyte (EN) pastures for4 consecutive weeks starting in April. Weekly measurements were collected to monitor physiological responses to consuming endophyte-infected tall fescue. In addition, PAP was measured every 4 weeks. Data were analyzed using a MIXED procedure of SAS, and statistical significance was determined at P < 0.05 and a tendency at 0.05 < P < 0.10, and evaluated the effects of treatment, age, week, and its interactions on BW, ADG, BCS, HCS, HSS and PAP. Exposure to EI did not affect BW, ADG, or BCS (P >0.05). Whereas, hair coat scores (1-5 scale) were significantly less for cattle consuming EN pastures (2.15 ± 0.05) compared with consuming EI pastures (2.31 ± 0.05; P < 0.05). Additionally, shedding scores (1-5 scale) were reduced in cattle consuming EN pastures (2.3±0.05) compared with consuming EI pastures (2.5±0.05; P< 0.05). There was a significant difference in PAP measurements in cattle exposed to EN pastures (37.16 ± 0.59 mm Hg) compared with EI pastures (31.31 ± 0.56 mm Hg; P < 0.0001). Additionally, PAP scores tended to deviate over the 14-week study between treatment groups (P = 0.0677). As expected, exposure to EI tall fescue resulted in greater HCS and HSS. However, the decrease in PAP in cattle consuming EI fescue was unexpected. Thus, further investigations are needed to examine the interaction between ergot alkaloid exposure on cardiovascular parameters such as PAP to potentially predict genetic differences in beef cattle to identify animals that would have a lower risk of developing fescue toxicosis.

Campylobacter jejuni is commonly isolated on selective media following incubation at 37 °C or 42 °C, but the impact of these temperatures on genome variation remains unclear. Previously, Campylobacter selective enrichments from the feces of steers before and after ceftiofur treatment were plated on selective agar media and incubated at either 37 °C or 42 °C. Here, we analyzed the whole genome sequence of C. jejuni strains of the same multilocus sequence typing (MLST)-based sequence type (ST) and isolated from the same sample upon incubation at both temperatures. Four such strain pairs (one ST8221 and three ST8567) were analyzed using core genome and whole genome MLST (cgMLST, wgMLST). Among the 1970 wgMLST loci, 7–25 varied within each pair. In all but one of the pairs more (1.7–8.5 fold) new alleles were found at 42 °C. Most frameshift, nonsense, or start-loss mutations were also found at 42 °C. Variable loci CAMP0575, CAMP0912, and CAMP0913 in both STs may regularly respond to different temperatures. Furthermore, frameshifts in four variable loci in ST8567 occurred at multiple time points, suggesting a persistent impact of temperature. These findings suggest that the temperature of isolation may impact the sequence of several loci in C. jejuni from cattle.

IntroductionExtralabel drug use (ELDU) is defined as the use of an FDA-approved medication in a manner that differs from what is provided on the label of the medication.1 Administration of the medication to a different species or at a different dose, volume, route, duration, indication, or frequency than indicated on the label is considered ELDU. Extralabel drug use also requires an extended withdrawal period to avoid violative residues, and practitioners can get advice on withdrawal intervals (WDIs) following ELDU from the Food Animal Residue Avoidance and Depletion Program (FARAD). Penicillin is one of the most commonly used

Limited knowledge exists regarding the use of lidocaine as a prokinetic in ruminants and camelids to treat gastrointestinal ileus. In this retrospective study, ruminant and camelid cases diagnosed with ileus and treated with a lidocaine constant rate of infusion were assessed for adverse reactions and medical outcomes. A review of medical records was performed to identify cases in which lidocaine was administered as a prokinetic. Ten cases were identified consisting of 8 cattle, 1 goat, and 1 alpaca. Nine animals improved with a lidocaine treatment. No adverse effects were reported during lidocaine administration. Nine animals were discharged, and 1 was euthanized.

Widespread dissemination of extended-spectrum beta-lactamase (ESBL) Escherichia coli (E. coli) in animals, retail meats, and patients has been reported worldwide except for limited information on small ruminants. Our study focused on the genotypic characterization of ESBL E. coli from healthy sheep and their abattoir environment in North Carolina, USA. A total of 113 ESBL E. coli isolates from sheep (n = 65) and their abattoir environment (n = 48) were subjected to whole-genome sequencing (WGS). Bioinformatics tools were used to analyze the WGS data. Multiple CTX-M-type beta-lactamase genes were detected, namely blaCTX-M-1, blaCTX-M-14, blaCTX-M-15, blaCTX-M-27, blaCTX-M-32, blaCTX-M-55, and blaCTX-M-65. Other beta-lactamase genes detected included blaCMY-2, blaTEM-1A/B/C, and blaCARB-2. In addition, antimicrobial resistance (AMR) genes and/or point mutations that confer resistance to quinolones, aminoglycosides, phenicols, tetracyclines, macrolides, lincosamides, and folate-pathway antagonists were identified. The majority of the detected plasmids were shared between isolates from sheep and the abattoir environment. Sequence types were more clustered around seasonal sampling but dispersed across sample types. In conclusion, our study reported wide dissemination of ESBL E. coli in sheep and the abattoir environment and associated AMR genes, point mutations, and plasmids. This is the first comprehensive AMR and WGS report on ESBL E. coli from sheep and abattoir environments in the United States.