Journal of the American Association for Laboratory Animal Science : JAALAS最新文献

Total intravenous anesthesia (TIVA) is an alternative to inhalant anesthesia when inhalant anesthesia is unavailable or contraindicated. This study investigated the anesthetic efficacy of tiletamine-zolazepam (TZ) through continuous rate infusion in sheep undergoing a 120-minute noninvasive imaging procedure. We hypothesized that the TZ continuous rate infusion would provide effective general anesthesia for imaging. Six male Dorset sheep were sedated with 4-6 mg/kg TZ intramuscularly, intubated, and maintained on 5-15 mg/kg/h TZ intravenous continuous rate infusion. Measured anesthetic parameters included heart rate, oxygen saturation (%SpO2), end-tidal carbon dioxide (ETCO2), body temperature, and direct arterial blood pressure (systolic, diastolic, and mean); blood gas analysis was performed during anesthesia. Time to extubation and standing (recovery) were measured. Other clinical observations (thrashing, activity, vocalization, and general appearance) were also assessed throughout recovery. Heart rate, %SpO2, ETCO2, body temperature, and direct arterial blood pressure were stable throughout imaging anesthesia. Time to extubation and standing (recovery) were 25 ± 6.5 and 34 ± 8.0 minutes, respectively. No abnormal clinical observations were noted. These data suggest that TZ TIVA provides effective general anesthesia for up to 120 minutes of noninvasive imaging.

This study aimed to establish a comprehensive and accurate numerical chest X-ray radiograph (CXR) scoring system in cynomolgus macaques by using image intensity values from healthy, tuberculosis (TB)-free animals as references. The CXRs were obtained in both dorsoventral and lateral postures from 90 macaques and viewed by the RadiAnt DICOM Viewer software version 2023.1. The mean and maximum intensity values were analyzed and showed significant differences between sex (male and female) and age class (juvenile and subadult/adult), varying based on body sizes. The cutoff values were, therefore, set separately and were tested for accuracy in detecting TB status in 18 naturally Mycobacterium tuberculosis-infected macaques, which were assessed for active tuberculosis infection (ATBI) using Xpert MTB/RIF Ultra at least once during a 12-month follow-up. Only the cutoff values of maximum lateral image intensity (MLIs) correctly identified TB infection in 100% of cases. Thus, the MLIs were selected to follow up on the development of TB lesions in those 18 Mycobacterium tuberculosis-infected macaques. The lateral digital radiograph was divided further into 9 areas, and the MLIs can predict the progression of TB lesions, which were most likely located in the dorsal part of the cranial lung lobe between thoracic vertebrae 1 (T1) to T4. Finally, the CXR results of another group of 8 Mycobacterium tuberculosis-exposed macaques, whose TB status was either uninfected, latent, or ATBI, were compared between a blind test by an expert radiologist and our established CXR scoring system. The blind test results showed 62.5% (5/8) agreement with our scoring system. This suggests that the CXR-MLI scoring system can be used as a supplementary tool for TB diagnosis in cynomolgus macaques.

Rabbits are commonly used as surgical models, thus requiring analgesics for painful procedures and optimal animal welfare. Buprenorphine, a partial µ opioid, is commercially available in various concentrations and sustained-release formulations and has historically been used as an analgesic in rabbits. A topical long-acting buprenorphine formulation (Zorbium, Bup-TP) has been approved for analgesic use in cats but has not yet been evaluated in rabbits. The present study evaluated the plasma concentrations and pharmacokinetic parameters of Bup-TP in New Zealand white rabbits (Oryctolagus cuniculus). Healthy adult male (n = 4) and female (n = 4) New Zealand white rabbits were used in a randomized crossover design and received a single high (7 mg/kg) and low (3 mg/kg) dose of Bup-TP. In this study, Bup-TP achieved a plasma blood concentration >0.25 ng/mL starting at 0.5 hours after dosing that was maintained up to 72 hours after dosing in adult New Zealand white rabbits. Compared with baseline, fecal and urinary output were reduced for an average of 3.5 days after dosing; food consumption was reduced for an average of 10 days after dosing. All resolved with time and supportive care. No lesions were grossly visible on any rabbit at site of application. Bup-TP may be an effective, long-lasting, and noninvasive method of providing analgesia in rabbits. Future study is recommended to optimize dosing and procedural analgesic efficacy.

Nude mice were inoculated with a nonpathogenic Corynebacterium bovis isolate (NPI) or Corynebacterium amycolatum to assess whether either could prevent skin lesions following inoculation with a pathogenic C. bovis isolate (PI). Crl:NU(NCr)-Foxn1nu mice (n = 6/group) were randomized into 6 groups: NPI (108 colony-forming units [CFU]); C. amycolatum (108 CFU); NPI or C. amycolatum followed 2 weeks later by PI (104 CFU); and negative and positive controls receiving sterile media or the PI (104 CFU), respectively. Colonization was assessed biweekly using isolate-specific PCR assays. Skin lesions were scored 0 to 5 daily for 4 or 6 weeks, at which point skin biopsies were collected, evaluated, and scored. No mice inoculated with the NPI and subsequently infected with the PI developed clinical signs, nor was a significant amount of the PI detected by PCR. Mice inoculated with C. amycolatum before the PI developed milder, delayed skin lesions reaching a significantly lower mean peak clinical score (MPCS; 1.2 ± 0.4) as compared with the positive control (MPCS 2.5 ± 0.5). The C. amycolatum-inoculated mice with and without PI had similar total histopathology scores, both of which were significantly higher than those for the mice inoculated with the NPI followed by the PI. These results led to evaluation of a practical exposure strategy in which nude mice (n = 6/group) were housed on NPI seeded bedding (SB) for 3 or 7 days prior to PI administration; mice housed on C. bovis-free bedding served as controls. Only 1 of 12 mice housed on SB receiving the PI developed Corynebacterium-associated hyperkeratosis (peak score of 4), whereas all unvaccinated mice receiving the PI developed Corynebacterium-associated hyperkeratosis (MPCS 2.83 ± 0.69). The PI was not detected in the SB + PI groups until 21 days postinfection with the PI. There was no significant difference in total histopathology scores across groups, but the histopathology scores were lower in mice receiving the SB.

Laboratory rats (Rattus norvegicus) are common animal models used in biomedical, psychological, and toxicological research. Their long-established research use has driven the progressive refinement of experimental techniques so that associated pain/distress may be ameliorated. One of these refinements is the use of opioids to provide analgesia. Buprenorphine, a partial mu-opioid agonist with high affinity for mu receptors, is commonly used for rodents, as the longer duration of action compared with morphine reduces the need for direct handling during administration of supplemental doses. While conventional buprenorphine (CB) requires dosing two to four times per day to provide sufficient pain control in many mammalian species, a novel, highly concentrated formulation of buprenorphine (HCB; Simbadol) is the first FDA-approved, veterinary-specific opioid labeled for every 24-hour dosing in cats (Felis catus). We hypothesized that, at the labeled feline dose of 0.24 mg/kg SC, HCB would achieve buprenorphine serum concentrations ≥1 ng/mL in older adult female Sprague-Dawley rats for at least 12 to 24 hours. Mean peak serum concentrations of 13.79 ± 6.76 ng/mL occurred 0.5 hour after administration. Twelve hours postadministration, the mean serum concentration was 2.12 ± 0.59 ng/mL with all treated rats maintaining individual serum concentrations well above 1 ng/mL. Twenty-four hours postadministration, the mean serum concentration was 1.02 ± 0.33 ng/mL with 4 of 6 rats maintaining individual serum concentrations of greater than or equal to 0.99 ng/mL. With the exception of a minor, focal injection site reaction in one animal, none of the other known side effects of opioid administration in rats were observed. These results support that administration of HCB at 0.24 mg/kg SC to older adult female SD rats produces serum buprenorphine concentrations consistent with analgesia for at least 12 hours and for up to 24 hours in some rats.

Management of nonhuman primates (NHPs) in the laboratory setting is complex. Medical management often involves techniques aimed at minimizing the impact on the animals' welfare, while considering the species-specific characteristics, research aims, and clinical needs of the patient. The current practice, at our institution, for administration of enrofloxacin has been to employ intramuscular injection, which may require brief restraint that can result in increased stress for the animal when applied throughout the course of a therapeutic regimen. Alternatively, oral dosing of standard veterinary tablet formulations has resulted in inconsistent administration, requiring supplementation with an injectable product if the animal becomes unwilling to take the medication. This inconsistency led us to investigate alternative methods of administration. Basing our efforts on previous work performed in macaques, we aimed to determine the pharmacokinetic characteristics of the injectable formulation of enrofloxacin when administered orally to one species of primate, the olive baboon (Papio anubis). Our work demonstrated that injectable enrofloxacin administered orally at 10 mg/kg resulted in higher serum levels than the intramuscular administration group for both enrofloxacin and its active metabolite, ciprofloxacin. In addition, our results support oral administration of enrofloxacin injectable product at intervals of up to once every 24 to 48 h when given at a dose of 10 mg/kg.

Buprenorphine is an opioid used for pain management in veterinary medicine but which requires frequent dosing to maintain therapeutic levels. Sustained-release buprenorphine (BSR) formulations can overcome this limitation, but genera- or species-specific studies that determine the time profiles of buprenorphine after dosing are sparse for NHPs. The objective of this study was to determine the plasma buprenorphine concentrations for 72 hours after a single subcutaneous administration of 0.2 mg/kg BSR or Ethiqa XR (EXR), an FDA-indexed, extended-release buprenorphine formulation, in owl monkeys. Blood samples were taken before and at 1, 4, 8, 24, 48, and 72 hours after administering either formulation to determine plasma buprenorphine concentrations. Clinical observations were also performed. A single 0.2 mg/kg dose of BSR and EXR raised plasma buprenorphine concentrations above the hypothesized therapeutic threshold for NHPs of 0.1 ng/mL within 1 hour of administration and maintained these levels for at least 72 hours. However, this dose did not sustain buprenorphine concentrations above the human efficacy threshold of 0.5 ng/mL for 72 hours. A subsequent study evaluated a single dose of 0.3 mg/kg EXR to determine whether this dose sustained plasma buprenorphine levels >0.5 ng/mL for 72 hours. Most owl monkeys reached this threshold and maintained plasma buprenorphine concentrations >0.5 ng/mL with this dose, albeit with increased side effects, including sedation and ptyalism. Injection site reactions were not observed in any animals during any study. In sum, this work indicates that a single subcutaneous dose of 0.2 mg/kg BSR or EXR can maintain buprenorphine above the hypothesized therapeutic threshold for NHPs of 0.1 ng/mL for 72 hours, but the EXR dose must be increased to reach the human efficacy threshold for 72 hours in owl monkeys.

Methodological status quo is often closely guarded in animal research because changes are seen as a threat to approaches that have proven successful. Current practices are often considered within the group as "best practice." Perioperative analgesia is an important consideration in humane animal research to prevent central sensitization and can contribute to the benefits of multimodal anesthesia, but many research groups do not provide preoperative analgesia to pregnant ewes. We conducted this study to challenge the belief that preoperative buprenorphine negatively impacts the recovery of the ewe and therefore fetal health. Pregnant ewes at approximately 85 days of gestation were divided into 2 groups (each n = 6) that all had the same hysterotomy and fetal catheterization surgery performed. The first group received buprenorphine (0.3 mg, SC) preoperatively, and the second group received the buprenorphine postoperatively. Isoflurane use, time to each step of the recovery process, intraoperative maternal plasma cortisol, and fetal arterial blood values after 4 days of recovery were compared between groups. Equivalence of outcomes between groups was assessed while controlling for potential confounding variables (maternal body weight and length of isoflurane) using 2 one-sided tests with regression adjustment. Average isoflurane concentration after induction, maternal cortisol levels, fetal blood pH, and fetal blood pO2 were equivalent between the groups. The time from cessation of isoflurane to the time of spontaneous breath or extubation and the time from extubation to time of eating or standing were all shorter in the preoperative buprenorphine group. Fetal hematocrit was also lower in the preoperative buprenorphine group. Our study not only refutes that preoperative buprenorphine causes prolonged recovery of the pregnant ewe and detrimental health effects to the fetus but also describes the benefits of preoperative buprenorphine.

In laboratory mice, the 21-day weaning standard is the most commonly applied strategy across institutions. However, this strategy has numerous drawbacks, including potential for litter overlap, pup mortality, and weaning extensions. In pursuit of a more objective marker for weaning, we compared the short-term growth of C57BL/6J mice weaned at 3 different body lengths. To recapitulate various weaning scenarios, mice (n = 90) were weaned at a litter average of 5.5, 6, or 6.5 cm. Body lengths and weights of mice were measured twice weekly from weaning to 10 weeks of age. Resulting growth curves revealed no significant differences in body length or body weight found across treatment groups. Although all groups achieved similar adult body length and body weight, unexpected mortality was experienced in the 5.5-cm group (n = 11). Multiple blinded observer comparisons did not result in significant inconsistencies in body length measurements. Our findings indicate that C57BL/6J mice can be safely weaned at an average minimum litter body length of 6 cm. This body length allows for normal physical development into adulthood without the requirement for additional nutritional support. Furthermore, the use of body length is a practical and reliable tool for personnel charged with determining weaning readiness in mice.