A Survey of Laboratory Animal Veterinarians Regarding Mouse Welfare in Biomedical Research

The quality of research animal welfare is undeniably linked to the quality of scientific results generated from the animals. Although mice are the most commonly used mammalian species in biomedical research, little information is available about what factors should be considered to promote future progress. To address this issue, the Animal Welfare Committee of the American Society of Laboratory Animal Practitioners (ASLAP) surveyed laboratory animal veterinarians to obtain their opinions about the welfare of mice and to consider the roles of 5 factors that significantly affect animal welfare in biomedical research: husbandry, clinical care, experimental use, regulatory oversight, and training. The survey revealed that 95% of veterinarians scored mouse welfare as acceptable to excellent, although areas for improvement remain. These areas include: 1) training of researchers performing experimental procedures; 2) the frequency of monitoring mice likely to experience pain and distress due to experimental manipulation; 3) inclusion of the institutional veterinary staff in the monitoring of mice likely to experience pain and distress; 4) continued improvement in the environmental enrichment provided to mice; 5) the ability of the IACUC to ensure that instances of noncompliance are fully addressed in order to prevent reoccurrence both within laboratories and among other research groups at the institution; and 6) reliance on non-veterinarians to perform examinations, diagnose disease, and prescribe the treatment of sick or injured mice.

Pharmacokinetics and Adverse Effects of 3 Sustained-release Buprenorphine Dosages in Healthy Guinea Pigs (Cavia porcellus)

In guinea pigs, studies addressing the efficacy, safety, and pharmacokinetic profiles of different sustained-release buprenorphine (SRB) formulations are still in their infancy. Here we assessed the pharmacokinetic profiles of 3 SRB dosages (SR-LAB, ZooPharm; SRBLow, 0.15 mg/kg; SRBMedium, 0.3 mg/kg; and SRBHigh, 0.6 mg/kg) for 72 h after a single subcutaneous administration to 8 (4 male and 4 female) healthy guinea pigs. Body weight, fecal output, and cortisol levels were also monitored and the results compared with those of the sham group. Within the first h after administration, the maximal plasma concentration (Cmax) of the drug was 64.3 ± 9.2 ng/mL (males) and 71.3 ± 3.7 ng/mL (females) in the SRBHigh group; 11.5 ± 3.2 ng/mL (males) and 6.9 ± 0.9 ng/mL (females) in the SRBMedium group; and 2.3 ± 0.8 ng/mL (males) and 2.0 ± 0.5 ng/mL (females) in the SRBLow group. After 72 h, therapeutic levels of the drug (>1 ng/mL) were observed only in guinea pigs treated with SRBHigh (both sexes) and males treated with SRBMediu cm. Fecal output (quantity and distribution) and body weight were significantly lower in the SRB groups as compared with the sham group, and with the SRBHigh group showing larger reductions. Baseline levels of serum cortisol in healthy females (1440 ± 106 ng/mL) were significantly greater than in males (550 ± 66 ng/mL). But, independent of the sex, SRB administration significantly reduced those levels. In conclusion, the data indicate that all 3 SRB dosages can be safely used in guinea pigs. However, therapeutic levels of the drug were observed for at least 48 h only guinea pigs treated with SRBHigh and SRBMedium. Further investigation is needed to determine if these dosages can alleviate pain in guinea pigs.

Phylogenetic analysis of a highly conserved region of the polymerase gene from 11 coronaviruses and development of a consensus polymerase chain reaction assay

Viruses in the genus Coronavirus are currently placed in three groups based on antigenic cross-reactivity and sequence analysis of structural protein genes. Consensus polymerase chain reaction (PCR) primers were used to obtain cDNA, then cloned and sequenced a highly conserved 922 nucleotide region in open reading frame (ORF) 1b of the polymerase (pol) gene from eight coronaviruses. These sequences were compared with published sequences for three additional coronaviruses. In this comparison, it was found that nucleotide substitution frequencies (per 100 nucleotides) varied from 46.40 to 50.13 when viruses were compared among the traditional coronavirus groups and, with one exception (the human coronavirus (HCV) 229E), varied from 2.54 to 15.89 when compared within these groups. (The substitution frequency for 229E, as compared to other members of the same group, varied from 35.37 to 35.72.) Phylogenetic analysis of these pol gene sequences resulted in groupings which correspond closely with the previously described groupings, including recent data which places the two avian coronaviruses--infectious bronchitis virus (IBV) of chickens and turkey coronavirus (TCV)--in the same group [Guy, J.S., Barnes, H.J., Smith L.G., Breslin, J., 1997. Avian Dis. 41:583-590]. A single pair of degenerate primers was identified which amplify a 251 bp region from coronaviruses of all three groups using the same reaction conditions. This consensus PCR assay for the genus Coronavirus may be useful in identifying as yet unknown coronaviruses.

Detection of enterotropic mouse hepatitis virus fecal excretion by polymerase chain reaction

A reverse transcription and polymerase chain reaction method was developed and used to detect fecal excretion of enterotropic mouse hepatitis virus (MHV). A nested set of primers for polymerase chain reaction was located in the polymerase region of the MHV genome. The assay was used to follow the time course of enterotropic MHV excretion in mice after oronasal inoculation with the virus. The assay detected MHV genome excretion in all mice beginning on day 3 through day 21 after inoculation. No MHV genome was detected in inoculated mice on or after day 27 following inoculation. This time course of detection of excreted virus corresponded to the period of infectivity of this isolate in a previous study. These results indicate that reverse transcription and polymerase chain reaction are useful for enterotropic MHV detection in specimens that are easily and noninvasively obtained and are clinically relevant.

Monoclonal antibody solution hybridization assay for detection of mouse hepatitis virus infection

A monoclonal antibody solution hybridization (MASH) assay was developed to detect fecal excretion of mouse hepatitis virus (MHV). The assay used a biotinylated cDNA probe to detect viral RNA target sequences by hybridization in solution, capture of hybrids on the solid phase with antibiotin antibody, and immunoassay with an enzyme-labelled monoclonal antibody specific for DNA-RNA hybrids. The MASH assay was used to monitor the time course of enterotropic MHV excretion after oronasal inoculation. Infectivity of the inoculated mice was simultaneously monitored with sentinel animals. The MASH assay detected MHV excretion in all inoculated mice, with the highest mean excretion levels occurring from day 3 through day 9 postinoculation. Mean excretion then decreased gradually to below detection limits by day 21 postinoculation. Sentinels became infected on exposure to inoculated mice up to but not after day 21 postinoculation. Infected sentinel mice showed a time course of virus excretion similar to that of inoculated mice. These results indicate that the MASH assay is useful for rapid, sensitive, and specific detection of MHV in clinical specimens from laboratory mice.

Effects of dichlorvos treatment on mouse reproduction

To test whether exposure to dichlorvos vapors for treatment of mouse ectoparasites resulted in temporary cessation of breeding, we exposed harem breeding groups of mice to varying concentrations of dichlorvos vapors and examined the effects of exposure on litter frequency and litter size. All exposure levels resulted in decreased plasma cholinesterase concentrations in treated mice for up to 10 days following the completion of exposure. Litter frequency and size were unaffected by dichlorvos exposure, and gestation times were not prolonged. Therefore, treatment with dichlorvos vapors during breeding did not affect reproduction in exposed mice.

Suppression of immune response induction in Peyer's patch lymphoid cells from mice infected with mouse hepatitis virus

Multiple previous studies have demonstrated significant alterations of immunologic parameters associated with mouse hepatitis virus (MHV) infection, but effects of the virus on mucosal lymphoid cells have not been examined. Coincident with a natural outbreak of MHV at our institution, we noted alterations in immunoglobulin secretion by mature Peyer's patch B cells under an inductive stimulus provided by dendritic cells and mitogen-activated T cells (DC-T). MHV was isolated from mice affected during the outbreak, and experimental infection of mice with the isolate consistently resulted in failures of immunoglobulin secretion by cocultures of Peyer's patch DC-T and B cells. In subsequent experiments, MHV appeared to negatively affect DC-T more than B cells. Therefore, the effects of inapparent MHV infection on experimental mucosal immune responses can result from natural infection and can be experimentally reproduced.

Rotavirus-associated diarrhea in a commercial rabbitry

An epizootic of diarrheal disease occurred in a commercial specific-pathogen-free rabbitry, and was characterized by sudden onset, rapid spread, and high morbidity and mortality among sucklings. Affected rabbits rapidly became dehydrated and most died within two days of the onset of diarrhea. Eight of these rabbits were necropsied. Five had blunted and fused small intestinal villi with attenuated villous enterocytes. A rotavirus was isolated from four rabbits, and five survivors of affected litters had strong antibody responses to rotavirus.

Risk factors for salmonellosis in hospitalized horses

A case-control study to identify risk factors associated with isolation of Salmonella was accomplished, using data from records of horses hospitalized in the period July 1971 through June 1982. Horses in which nasogastric tubes were passed were at 2.9 times greater risk of having Salmonella isolated, compared with horses that did not undergo this procedure. Horses treated with antibiotics parenterally were at 6.4 times greater risk, and those treated with antibiotics orally and parenterally were at 40.4 times greater risk of developing salmonellosis, compared with horses not receiving such treatment. Horses admitted because of colic were 4.2 times as likely to have Salmonella isolated as those admitted for other reasons. Breed, age, and type of surgery did not appear to be risk factors. The risk factors identified and the magnitude of their association with Salmonella isolation were similar to those observed in a preceding study.