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

Leopard geckos (Eublepharis macularius) with lemon frost morphologies are predisposed to iridophoroma, attributed to a tumor suppressor gene mutation also associated with melanoma in humans. In this case series, we describe the clinical presentation, diagnostics, complications, and pathology of iridophoroma in 4 adult leopard geckos, including 2 super lemon frost females and 2 lemon frost males. All animals presented with hyporexia, intermittent lethargy, weight loss, submandibular masses, and oral plaques. In addition, females demonstrated asymmetric coelomic distension, and one male developed altered mentation. Initial differential diagnoses included metabolic disorders, gastrointestinal infectious diseases, and neoplasia. During clinical management of these cases, ultrasonography revealed hyperechoic hepatic nodules in all animals. Fine needle aspiration (FNA) of the subcutaneous submandibular masses found clusters of mesenchymal cells with abundant cytoplasm containing fine birefringent granules. Due to continued decline and poor prognosis, animals were euthanized and submitted for necropsy. Gross examination of all 4 geckos demonstrated skin thickening by white masses throughout the body and multifocal white hepatic plaques. Two females showed yellow, enlarged ovaries, and one of the males had hard intraluminal debris in the urinary bladder. Histopathology of the skin throughout the body showed the dermis and subcutis were infiltrated by myriad pleomorphic, ovoid to fusiform, brown-pigmented neoplastic cells characterized by abundant birefringent intra- and extracellular granules. FNA, ultrasound, necropsy, and histopathology results were consistent with diagnosis of malignant iridophoroma with metastasis to multiple visceral organs including the brain and ovary. In addition, both females developed preovulatory follicular stasis (POFS)-associated oophoritis, and one of the males demonstrated urolithiasis; all of which were considered as metabolic imbalance-related pathology due to hyporexia or tumor invasion. This report illustrates the diagnostic features of FNA, ultrasound, and histopathology of malignant iridophoroma in leopard geckos. It also discusses POFS and urolithiasis as multisystemic sequelae to malignant tumors in geckos.

Osteoarthritis is the leading cause of disability in the United States and affects approximately half of adults over the age of 65. Many osteoarthritis patients take nonsteroidal anti-inflammatory drugs (NSAIDs) on a long-term basis, often concurrently with proton pump inhibitors (PPIs), such as omeprazole, to prevent gastric ulceration. Mice (Mus musculus) are a commonly used animal model of osteoarthritis. There are little data regarding long-term administration of NSAIDs or coadministration of PPIs and NSAIDs in mice. This study sought to determine if administration of carprofen, a commonly used veterinary NSAID, has adverse effects when administered for 21 days and if coadministration of omeprazole reduces the incidence of adverse effects. Four groups of C57BL/6J male (n = 5/group) and female (n = 5/group) mice were weighed daily and administered 10 mg/kg carprofen and 8.2 mg/kg omeprazole, 10 mg/kg carprofen, 8.2 mg/kg omeprazole, or control suspension once daily by oral gavage for 21 days. All mice were euthanized, and complete blood count (CBC), serum chemistry, fecal occult blood, and pyloric histopathology and gastritis scoring were conducted. All animals remained clinically healthy for the duration of the study. White blood cell counts (WBCs) and platelets were significantly lower in the carprofen and omeprazole group. Neutrophil counts were significantly lower in the carprofen and omeprazole and the carprofen groups. Compared with the control group, albumin was significantly higher in the carprofen group. Fecal occult blood tests were negative for all animals. No animals had pyloric mucosal ulceration, and gastritis scores were not significantly different between groups. Body weight significantly decreased for all groups over time, with no significant differences among treatment groups. Carprofen and omeprazole may be safely administered to C57BL/6J mice for 21 days but may induce significant changes in CBC and serum chemistry.

Federal regulations require that appropriate analgesia be provided to laboratory animals for pain control. Carprofen and buprenorphine are 2 common analgesics used for laboratory mice (Mus musculus). However, given the potential gastrointestinal side effects that these analgesics have in various species, the impact of these analgesics on mice used in metabolic studies could be concerning. To investigate the impact of carprofen and sustained-release buprenorphine on food consumption, activity level, and whole-body metabolism, we administered carprofen alone or in combination with sustained-release buprenorphine to mice that underwent jugular vein and carotid artery catheterization, or a sham surgery. The mice were individually housed in instrumented metabolic cages to continuously quantify food consumption, activity levels, and energy expenditure by indirect calorimetry. We hypothesized that catheterized mice receiving both carprofen and sustained-release buprenorphine would have decreased food consumption and increased activity level compared with mice which received sham surgery and carprofen, and that catheterized mice treated with carprofen only would have similar food consumption and activity level as sham mice which received carprofen. Our results demonstrate that during the initial 12 hours after surgery, catheterized mice that received both carprofen and sustained-release buprenorphine were more active than sham mice which received carprofen, and they were more active and consumed more food than catheterized mice which received carprofen only. Our study demonstrated that analgesia regimen can affect metabolic parameters, thus, researchers should carefully consider the effects that analgesic drugs can have on mice when designing metabolic or behavioral experiments.

Use of soiled bedding sentinels (SBS) for rodent colony health monitoring is limited by inconsistent pathogen detection, reliance on live animals, high costs, and labor intensity. Sentinel-free soiled bedding (SFSB) offers a viable alternative for all rodent housing systems, overcoming limitations by using PCR testing of matrices exposed to soiled bedding. As an alternative, a matrix may be exposed to all cages via direct colony dredging (DCD). This study compared pathogen detection and costs between SFSB, DCD, and SBS for mice housed in individually-ventilated cage rack system cages. For each study rack, SFSB was performed with one matrix shaken in composite soiled bedding, while DCD was performed with a second matrix exposed to all soiled cages on the rack using a dredging method. We hypothesized that the SFSB and DCD matrices would detect Rodentibacter heylii, Rodentibacter pneumotropicus, Helicobacter typhlonius, Helicobacter mastomyrinus, Helicobacter hepaticus, Helicobacter bilis, Helicobacter rodentium, Helicobacter ganmani, and murine norovirus (MNV) with equal or superior efficacy to SBS, at a comparable or reduced program cost. All SBS failed to detect R. heylii, R. pneumotropicus, H. typhlonius, H. mastomyrinus, H. hepaticus, H. bilis, H. rodentium, and H. ganmani when tested by fecal PCR, and 25% failed to detect MNV when tested via serology. In contrast, SFSB and DCD matrices detected MNV, R. heylii, R. pneumotropicus, H. typhlonius, H. mastomyrinus, H. hepaticus, H. bilis, H. rodentium, and H. ganmani even with low pathogen prevalence, although neither method achieved 100% detection. DCD had negative ergonomic, workflow, and labor challenges compared with SFSB. Overall, SFSB and DCD had reduced costs and superior pathogen detection compared with SBS, while SFSB provided the most efficient and user-friendly approach for health monitoring by this institution.

Buprenorphine is a commonly used analgesic in laboratory rodents for procedures of moderate to severe pain. We evaluated the pharmacokinetic properties of an immediate-release formulation of buprenorphine (Bup-IR) and an extended-release formulation (Bup-ER) in both sexes of 4 different strains of mice (C57BL/6, CD-1, BALB/c, and CB17 SCID) commonly used for dermatology and oncology research at our institution. Skin at the injection site was evaluated for 7 days postinoculation and scored for reactions and then collected for histopathologic analyses. Body weights were evaluated at 1 and 4 days postinoculation. We hypothesized that the administration of Bup-ER would provide a longer duration of blood drug concentration (>1 ng/mL; minimum analgesia threshold) compared with single-dose Bup-IR. We analyzed the standard dose for Bup-IR (0.3 mg/kg) and for Bup-ER (1 mg/kg), along with saline vehicle with blood collected at 1, 4, 24, 48, 72, and 96 hours following administration of Bup-ER and 0.25, 0.5, 1, 2, 3, 6, 9, 12, and 24 hours following administration of Bup-IR using MS. Bup-ER and Bup-IR levels were consistent among sexes of a given strain but varied between strains. Skin reactions, body weight loss, and histopathologic changes were greater in the Bup-ER-treated mice with some sex and strain differences. Due to changes found on histopathology of the skin sections taken from the injection site for Bup-ER-inoculated mice, a separate study to determine cytokine release following Bup-ER injection was performed and revealed only minor changes in a few cytokines. In conclusion, Bup-ER provided longer duration analgesia (>1 ng/mL) compared with Bup-IR. Based on differences found in the strains of mice evaluated, we recommend performing pharmacokinetic analyses for a given strain to determine the best dosing frequency and dose of buprenorphine (IR or ER) for procedures that require analgesia.

The purpose of this study was to track seroconversion in a cohort of 12, pair-housed, macaques that were previously screened negative for adeno-associated virus-9 neutralizing antibody (AAV9-NAb). Over a 6-month period, specific biosecurity strategies were implemented with the intention of understanding if following defined protocols could play a role in preservation of AAV9-NAb negative status. AAV9-NAb-negative animals were selected for shipment to the facility approximately 2 months after the initial screening. After arrival, animals were paired and housed in a single room with a dedicated housing corridor, cage wash, and equipment. They were then screened for AAV9-NAb status monthly by 2 different labs to confirm results and ascertain potential for variation of results. Upon initial screening at the facility (within one week of arrival), 2 of the 12 NHPs that were seronegative before shipment had seroconverted to AAV9-NAb positive status. The positive animals and their negative partners were moved to a different room but remained within the same isolated corridor with the same biosecurity practices. Serum that was taken on a monthly basis was also used to screen other AAVs. At the end of the 6-month period, AAV9 NAb status did not change from the time the animals were initially screened on site until the end of the study. Paired animals that were cohoused in the same cage with a positive partner did not seroconvert. Although a control group was not used to validate that biosecurity practices played a role in mitigating seroconversion, unpublished data from a facility employing less restricted biosecurity strategies suggest that the seroconversion process involves a more intricate process.

Infection with Corynebacterium bovis causes significant clinical disease in immunocompromised mice. The impact of antibiotics, administered prophylactically or symptomatically, on body weight, clinical condition, skin histopathology, and gut microbiota was assessed in NOD.Cg-Prkdcscid Il2rgtm1Wjl/SzJ (NSG) mice infected with C. bovis. Mice were untreated (n = 5) or received oral amoxicillin, sulfamethoxazole/trimethoprim (TMS), or azithromycin a day prior to C. bovis exposure (n = 5/antibiotic) or after clinical signs developed (n = 5/antibiotic). Body weights and clinical scores were ascertained weekly. Mice were euthanized 24 weeks after infection, or earlier if humane endpoints were reached. Skin biopsies and fecal samples were collected at necropsy for histopathology scoring and gut flora characterization. Mice treated with amoxicillin had significant improvement in their clinical signs for the duration of treatment; however, 2 mice treated prophylactically experienced severe weight loss that necessitated euthanasia. Amoxicillin-treated mice had aberrant gut microbiota, including Clostridioides difficile colonization. In contrast, mice treated with TMS had no difference in their clinical scores, and their skin pathology was more severe, compared with untreated mice. There was no difference between symptomatic and prophylactic treatment. Clinical disease in azithromycin-treated mice improved for ∼5 weeks, but ultimately clinical disease recrudesced despite continuing therapy. Mice treated prophylactically with azithromycin experienced severe weight loss that necessitated euthanasia. Changes in the intestinal flora were not appreciated in mice treated with TMS or azithromycin as compared with untreated controls. While clinical signs of C. bovis infection in NSG mice improved when treated with amoxicillin, marked changes in the intestinal flora of these animals require careful consideration of both animal health and experimental outcomes before its use. TMS and azithromycin did not ameliorate C. bovis-associated disease, and their use as therapeutics for C. bovis is not recommended. Untreated C. bovis infection was not life-limiting for up to 24 weeks in NSG mice.

Sentinel-free soiled bedding (SFSB) is a form of environmental health monitoring that is an efficient method for monitoring rodent colony health. In contrast to direct colony sampling (DCS), when using PCR testing, SFSB can detect both active and past infections and is a less invasive method, classifying it as refinement. In this study, we compared DCS and SFSB for quarantine health monitoring in terms of their effectiveness in detecting pathogens during a 14-day quarantine program. In addition, we performed a time and motion study to examine the time required for each sampling method. We hypothesized that SFSB testing for quarantine would exhibit a greater degree of sensitivity than DCS for the tested pathogen list and take less time to perform. Eleven shipping containers, each containing 4-5 male or female mice aged 6-11 weeks, were subjected to simulated shipping stress as would occur during importation. During the 14-day quarantine, DCS samples included oral swabs, adhesive pelt swabs, and fresh fecal pellets that were pooled per cage and collected on days 0 (baseline) and 7. Each cage was given its own soiled-bedding sampling system, and SFSB samples were comprised of 3 groups: day 0, day 7, and a combination of days 0 and 7. There were no statistically significant differences between the 3 different SFSB sample time points (day 0, day 7, and days 0 and 7 combined) for all pathogens evaluated (P > 0.05). In addition, there were no statistically significant differences between the DCS day 7 and the days 0 and 7 combined SFSB time point for all pathogens evaluated (P > 0.05). Furthermore, SFSB was shown to be less time-consuming than DCS. Thus, SFSB sampling should be considered for quarantine health monitoring programs, as it has similar sensitivity to DCS, is a refinement, and offers a time-saving benefit.

Cryopreservation of pronuclear stage embryos from superovulated mice is beneficial to safeguard genetically modified (GM) mouse strains as well as the efficient production of novel GM mouse strains. C57BL/6J female mice were superovulated with either anti-inhibin serum (AIS) or equine chorionic gonadotropin (eCG), and the resulting oocytes were inseminated via in vitro fertilization (IVF) to produce pronuclear stage embryos. A subset of fresh embryos was cultured in vitro to assess their developmental potential to the blastocyst stage, and the remaining embryos derived from either AIS or eCG superovulation methods were cryopreserved via vitrification and subsequently assessed to determine both in vitro and in vivo developmental competence. The percentage of IVF-derived fresh embryos that developed to 2-cell (92.9 ± 4.1 compared with 92.4 ± 4.2) and the blastocyst stage (91.9 ± 3.84 compared with 91.8 ± 7.9) from eCG and AIS, respectively, was not different (P = 0.89). The percentage of the vitrified pronuclear embryos that were intact after warming for eCG (93.08 ± 5.96) and AIS (88.0 ± 6.63) mice was different (P = 0.039). However, the percentage of IVF-derived vitrified warmed zygotes that developed to 2-cell (82.23 ± 7.18 compared with 83.9 ± 7.22) and the blastocyst stage (71.35 ± 7.76 compared with 74.52 ± 5.57) from eCG and AIS, respectively, was not different. Vitrified pronuclear embryos produced after either AIS or eCG-administered mice were in vitro cultured to 2-cell and surgically transferred into CD-1 surrogate mothers to compare pregnancy rates and live birth rates. There were no differences in percent pregnancy rates between eCG (85.7) and AIS (85.7) superovulation methods. Similarly, there were no differences in the percentage of live offspring between eCG (27.6) and AIS (23.2) superovulation methods. This study suggests that eCG and AIS superovulation methods yield similar in vitro and in vivo embryonic development rates following vitrification, and thus, AIS may be preferred, especially for the strains with difficulty in obtaining large quantities of oocytes or embryos for the production of GM mice or genome banking.