About

Derek Foster is associated with the College of Veterinary Medicine at NC State University, where he is involved in initiatives related to student engagement and the broader educational environment. The page highlights his role as the CVM Director of Student Engagement, indicating his focus on fostering a supportive and collaborative campus community for veterinary students. His work emphasizes enriching student experiences through extracurricular activities, research opportunities, and international programs, contributing to the development of future veterinary professionals. The information provided does not detail specific research areas, scientific contributions, or background beyond his leadership role in student engagement.

Research topics

• Medicine
• Biology
• Microbiology
• Internal medicine
• Veterinary medicine
• Computer Science
• Pharmacology
• Botany
• Agronomy
• Bioinformatics
• Animal science

Selected publications

• Investigating the Pharmacokinetics and Efficacy of Intramammary Ceftiofur Hydrochloride in Prevention of Udder Inflammation in Non‐Lactating Dairy Heifers

  Journal of Veterinary Pharmacology and Therapeutics · 2025-04-21 · 1 citations

  articleOpen access

  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.

  PublisherOA PDFDOI

• The route of administration of xylazine impacts the prolongation of local anesthesia in cattle

  American Association of Bovine Practitioners Conference Proceedings · 2025-03-26

  articleOpen access

  Xylazine prolongs the duration of lidocaine when administered as a distal paravertebral block in cattle. This study investigates if the observed effect is due to the perineural administration of xylazine with lidocaine or if it could be achieved by systemic administration of xylazine and perineural lidocaine.

  PublisherOA PDFDOI

• Pharmacokinetics of Orally Administered Phenazopyridine in Goats With Obstructive Urolithiasis

  Journal of Veterinary Internal Medicine · 2025-06-26

  articleOpen access

  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: ), 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.

  PublisherOA PDFDOI

• Influence of heat stress and fescue toxicosis on the pulmonary arterial pressure of beef heifers

  Journal of Animal Science · 2025-01-01 · 1 citations

  articleOpen access

  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.

  PublisherOA PDFDOI

• Impact of 3 colostrum replacement strategies on immunoglobulin G absorption efficiency, passive immunity, health, and growth in beef calves

  Journal of the American Veterinary Medical Association · 2025-08-15 · 1 citations

  articleOpen access

  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.

  PublisherDOI

• Pharmacokinetics of Ampicillin Trihydrate in Plasma, Interstitial, and Peritoneal Fluid Following Intraperitoneal or Intramuscular Administration in Steers at the Beginning of a Standing Flank Laparotomy

  Journal of Veterinary Pharmacology and Therapeutics · 2025-09-04

  articleOpen accessSenior author

  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.

  PublisherOA PDFDOI

• Four-site distal paravertebral blocks improve physiologic indicators of analgesia in the immediate postoperative period as opposed to a 3-site distal paravertebral block

  Journal of the American Veterinary Medical Association · 2025-08-01

  article

  Objective: To determine differences in surgical and postoperative analgesia between 3-site distal paravertebral (DPV) blocks and modified 4-site DPV blocks. Methods: 12 healthy dairy or dairy cross steers were randomized into 1 of 2 treatments, 3-site DPV block (3DPV) or 4-site DPV block (4DPV); 2 mg/kg of 2% lidocaine was administered at each site-lumbar vertebrae 1, 2, and 4 in the 3DPV group (6 mg/kg), and an additional injection at lumbar vertebrae 3 for the 4DPV group (8 mg/kg). Heart and respiratory rates, temperature, reaction scores, and surgical condition scores were collected. Postoperative pain scores and physiologic data were collected for 24 hours following surgery. An ordinal logistic mixed-effects model was used to compare surgical conditions, reaction scores, and pain scores. A linear mixed-effects model was used for normally distributed data. Results: The success rate of 3DPV blockade was 5 of 6 (83%), and that for 4DPV was 6 of 6 (100%). Only 11 steers were included in the data analysis due to the failed block. The 4DPV group had lower respiratory rates following the return to stall (32 ± 3 vs 44 ± 4 breaths/min; P < .019). Additionally, the 4DPV group had significantly lower heart rates immediately following the return to the stall (62 ± 8 vs 88 ± 9 beats/min; P < .036). No differences in pain scores or intraoperative conditions were identified. Conclusions: Adding an injection site at L3 in a DPV reduced postoperative heart rate and respiratory rate in steers following laparotomy. Clinical Relevance: Adding a fourth injection site at L3 decreases physiologic indicators of postoperative discomfort.

  PublisherDOI

• The neutralizing antibody, LY-CoV555, protects against SARS-CoV-2 infection in nonhuman primates

  UNC Libraries · 2024-06-12

  articleOpen access

  Severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) poses a public health threat for which preventive and therapeutic agents are urgently needed. Neutralizing antibodies are a key class of therapeutics that may bridge widespread vaccination campaigns and offer a treatment solution in populations less responsive to vaccination. Here, we report that high-throughput microfluidic screening of antigen-specific B cells led to the identification of LY-CoV555 (also known as bamlanivimab), a potent anti-spike neutralizing antibody from a hospitalized, convalescent patient with coronavirus disease 2019 (COVID-19). Biochemical, structural, and functional characterization of LY-CoV555 revealed high-affinity binding to the receptor-binding domain, angiotensin-converting enzyme 2 binding inhibition, and potent neutralizing activity. A pharmacokinetic study of LY-CoV555 conducted in cynomolgus monkeys demonstrated a mean half-life of 13 days and a clearance of 0.22 ml hour−1 kg−1, consistent with a typical human therapeutic antibody. In a rhesus macaque challenge model, prophylactic doses as low as 2.5 mg/kg reduced viral replication in the upper and lower respiratory tract in samples collected through study day 6 after viral inoculation. This antibody has entered clinical testing and is being evaluated across a spectrum of COVID-19 indications, including prevention and treatment.

  PublisherDOI

• Impact of florfenicol dosing regimen on the phenotypic and genotypic resistance of enteric bacteria in steers

  Scientific Reports · 2024-02-28 · 4 citations

  articleOpen accessSenior author

  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.

  PublisherOA PDFDOI

• Validation of a reference interval for symmetric dimethylarginine in healthy goats and its comparison to values in goats with obstructive urolithiasis

  Journal of Veterinary Internal Medicine · 2024-08-17 · 1 citations

  articleOpen access

  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.

  PublisherOA PDFDOI

Frequent coauthors

• Megan E. Jacob

  North Carolina State University

  28 shared

• Mark G. Papich

  North Carolina State University

  27 shared

• Jody L. Gookin

  North Carolina State University

  20 shared

• Jennifer L. Halleran

  North Carolina State University

  19 shared

• Hannah J. Sylvester

  North Carolina State University

  17 shared

• Timo Prange

  North Central State College

  17 shared

• Stephen H. Stauffer

  North Carolina State University

  15 shared

• Geoffrey Smith

  14 shared

Education

• PhD, Comparative Biomedical Sciences

  North Carolina State University

• DVM

  North Carolina State University

Awards & honors

• American Veterinary Medical Association Young Investigator o…
• Pfizer Distinguished Veterinary Teaching Award (2012)