Guinea Pig Colony Research Articles

Effect of Parental Age, Parity, and Pairing Approach on Reproduction in Strain 13/N Guinea Pigs (Cavia porcellus)

Guinea pigs are important animal models for human disease, and both outbred and inbred lines are utilized in biomedical research. The optimal maintenance of guinea pig colonies, commercially and in research settings, relies on robust informed breeding programs, however, breeding data on specialized inbred strains are limited. Here, we investigated the effects of parental age, parity, and pairing approaches on mean total fetus count, percentage of female pups in the litter, and pup survival rate after 10 days in strain 13/N guinea pigs. Our analysis of colony breeding data indicates that the average litter size is 3.3 pups, with a 25.2% stillbirth rate, a failure-to-thrive outcome in 5.1% of pups, and a 10 day survival rate of 69.7%. The only variable to significantly affect the reproductive outcomes examined was parental age (p < 0.05). In comparison to adults, both juvenile and geriatric sows had lower total fetus counts; juvenile boars had a higher percentage of females in litters, and geriatric boars had a lower 10 day survival rate of pups. These studies provide valuable information regarding the reproductive characteristics of strain 13/N guinea pigs, and support a variety of breeding approaches without significant effects on breeding success.

Genetic diversity of oral streptococci in the guinea pig as assessed by sequence analysis of the 16S rRNA and groEL genes

The aim of the present study was to characterize bacteria of the genus Streptococcus isolated from the oral cavity of the guinea pig as well as to assess the significance of these microorganisms as potential veterinary and human pathogens. Sixty-two streptococcal isolates recovered from 27 clinically healthy guinea pigs were examined genotypically by sequencing the 16S rRNA and groEL genes. Among these isolates, only 13 could be assigned to a species described previously (mainly Streptococcus parasanguinis, S. mitis and S. suis), and the majority of the remaining ones differed considerably from the streptococcal species known to date (16S rRNA and groEL sequence similarities were < 97% and < 87%, respectively). Based on 16S rRNA sequences, these unidentified isolates were divided into seven groups (clades), of which clades I through III comprised most of the isolates examined and had also the widest distribution among guinea pig colonies. Upon groEL gene sequence analysis, however, members of the three clades grouped together without forming such distinct clusters. The remaining clades distinguished by 16S rRNA sequencing could also be discerned by the second gene, and they contained only a few isolates often restricted to one or a few animal colonies. The present work reveals that the guinea pig mouth is inhabited by a vast number of phylogenetically diverse, so far unrecognized populations of streptococci, most of them being apparently host-specific genomospecies. On the contrary, S. parasanguinis and S. mitis are also common human commensals and S. suis is a well-recognized zoonotic pathogen.

Isolation and initial propagation of guinea pig adenovirus (GPAdV) in Cavia porcellus cell lines.

Background: The lack of adequate in vitro systems to isolate and propagate guinea pig adenovirus (GPAdV), a prevalent cause of respiratory illness of varaible severity in laboratory guinea pig colonies worldwide, has precluded its formal characterization to allow for the development of comprehensive diagnostic assays, and for the execution of complex pathogenesis and basic virology studies. Methods: Two strains of GPAdV were isolated in guinea pig ( Cavia porcellus) cell cultures from frozen archival infected animal tissue originated from colony outbreaks of pneumonia in Australia and the Czech Republic in 1996. Results: Commercially available guinea pig cell lines from colorectal carcinoma (GPC-16), fetal fibroblast (104-C1) and lung fibroblast (JH4 C1), and the tracheal epithelial cell line GPTEC-T developed in this study were able to support viral infection and early propagation. Sufficient viral DNA was recovered from cell cultures to PCR-amplify and obtain sequence data for the complete hexon gene and partial DNA polymerase and penton base genes. Phylogenetic analysis for the three regions of the genome provided strong evidence confirming GPAdV as a unique species in the genus Mastadenovirus. Conclusions: This study demonstrated the feasibility of propagating GPAdV in cultures of immortalized lines of GP cells of a variety of types, thus establishing a critical foundation for the development of a robust culture platform for virus stock production and titration. The generation and analysis of whole GPAdV genome sequences will provide additional data for a comprehensive description of the genetic organization of the viral genome and for a better assessment of genetic diversity between the two isolated strains.

Isolation and initial propagation of guinea pig adenovirus (GPAdV) in Cavia porcellus cell lines

Background: The lack of adequate in vitro systems to isolate and propagate guinea pig adenovirus (GPAdV), a prevalent cause of respiratory illness of varaible severity in laboratory guinea pig colonies worldwide, has precluded its formal characterization to allow for the development of comprehensive diagnostic assays, and for the execution of complex pathogenesis and basic virology studies. Methods: Two strains of GPAdV were isolated in guinea pig ( Cavia porcellus) cell cultures from frozen archival infected animal tissue originated from colony outbreaks of pneumonia in Australia and the Czech Republic in 1996. Results: Commercially available guinea pig cell lines from colorectal carcinoma (GPC-16), fetal fibroblast (104-C1) and lung fibroblast (JH4 C1), and the tracheal epithelial cell line GPTEC-T developed in this study were able to support viral infection and early propagation. Sufficient viral DNA was recovered from cell cultures to PCR-amplify and obtain sequence data for the complete hexon gene and partial DNA polymerase and penton base genes. Phylogenetic analysis for the three regions of the genome provided strong evidence confirming GPAdV as a unique species in the genus Mastadenovirus. Conclusions: This study demonstrated the feasibility of propagating GPAdV in cultures of immortalized lines of GP cells of a variety of types, thus establishing a critical foundation for the development of a robust culture platform for virus stock production and titration. The generation and analysis of whole GPAdV genome sequences will provide additional data for a comprehensive description of the genetic organization of the viral genome and for a better assessment of genetic diversity between the two isolated strains.

Isolation and initial propagation of guinea pig adenovirus (GPAdV) in Cavia porcellus cell lines

Background: The lack of adequate in vitro systems to isolate and propagate guinea pig adenovirus (GPAdV), a prevalent cause of respiratory illness of varaible severity in laboratory guinea pig colonies worldwide, has precluded its formal characterization to allow for the development of comprehensive diagnostic assays, and for the execution of complex pathogenesis and basic virology studies. Methods: Two strains of GPAdV were isolated in guinea pig ( Cavia porcellus) cell cultures from frozen archival infected animal tissue originated from colony outbreaks of pneumonia in Australia and the Czech Republic in 1996. Results: Commercially available guinea pig cell lines from colorectal carcinoma (GPC-16), fetal fibroblast (104-C1) and lung fibroblast (JH4 C1), and the tracheal epithelial cell line GPTEC-T developed in this study were able to support viral infection and early propagation. Sufficient viral DNA was recovered from cell cultures to PCR-amplify and obtain sequence data for the complete hexon gene and partial DNA polymerase and penton base genes. Phylogenetic analysis for the three regions of the genome provided strong evidence confirming GPAdV as a unique species in the genus Mastadenovirus. Conclusions: This study demonstrated the feasibility of propagating GPAdV in cultures of immortalized lines of GP cells of a variety of types, thus establishing a critical foundation for the development of a robust culture platform for virus stock production and titration. The generation and analysis of whole GPAdV genome sequences will provide additional data for a comprehensive description of the genetic organization of the viral genome and for a better assessment of genetic diversity between the two isolated strains.

Divergent Responses in the Gap Prepulse Inhibition of the Acoustic Startle Reflex in Two Different Guinea Pig Colonies.

Animal models of tinnitus rely on interpretation of behavioural or reflexive tests to determine the presence of this phantom perception. A commonly used test is the gap prepulse inhibition of acoustic startle (GPIAS), which is often combined with prepulse inhibition (PPI) to ensure that reduced GPIAS suppression is not due to hearing loss caused by the acoustic trauma commonly used to trigger tinnitus development. In our laboratory GPIAS and PPI are routinely used on two colonies of outbred tri-colour guinea pigs. However, our results show that these colonies show divergent results even before any tinnitus-inducing treatment, which impacts their suitability in tinnitus models. Although colony 1 and 2 show similar results in PPI (~95% of animals showing significant suppression), only ~30% of colony 2 also shows significant suppression in GPIAS compared to ~75% of colony 1. Cochlear sensitivity measured using compound action potentials showed no significant differences between colonies. Therefore, peripheral threshold loss was excluded as a possible factor. Our results show that similar strains of laboratory animals can show highly divergent results and GPIAS testing for tinnitus will not work for every animal strain. In addition, our data support the notion that PPI and GPIAS responses may rely on different neural circuitry.

Using Hysterectomy Rederivation to Produce Guinea Pigs (Cavia porcellus) Free of Guinea Pig Cytomegalovirus.

Due to similarities in placentation, guinea pigs can be used as models of human cytomegalovirus infection, but they must be free of guinea pig cytomegalovirus. Many commercial guinea pig colonies are enzootically infected with guinea pig cytomegalovirus, which can be transmitted vertically as well as horizontally through saliva, vaginal secretions, and milk. These characteristics make its eradication in a commercial setting challenging. Because embryo transfer technology in guinea pigs is in its infancy, it is not generally a viable option for obtaining animals free of guinea pig cytomegalovirus. However, a combination of hysterectomy rederivation and testing by PCR assay and serology of both dams and offspring from an enzootically infected colony produced offspring free of guinea pig cytomegalovirus.

Treatment and control of Trixacarus caviae infestation in a conventional guinea pig (Cavia porcellus) breeding colony.

A case of sarcoptic mange caused by Trixacarus caviae in a conventional guinea pig breeding colony is reported. The infestation was reported in a large colony of guinea pigs during the month of July, 2013 affecting 30 breeder guinea pigs. Severely infested animals were treated individually with subcutaneous injection of ivermectin 1% w/v (Neomec®) at the rate of 400µg/kg body weight 10days apart. Three doses of ivermectin were sufficient to eliminate the parasite which tested negative after 30days of the first treatment. The entire colony was given preventive dose of ivermectin spray (2mg/ml solution) following the same schedule. Strict hygienic measures were followed. New hair growth in the severely affected animals was evidenced on 30th day of treatment.

Interactions of chromatic and lens-induced defocus during visual control of eye growth in guinea pigs (Cavia porcellus)

It was recently demonstrated that chromaticity could affect eye growth and refractive development in guinea pigs but it remained unclear whether correction with spectacle lenses could balance these effects and how retinal responses change with different spectral compositions of light. Three illumination conditions were tested: blue, red and white light. Animals were raised without or with monocular spectacle lenses from three to seven weeks of age. Luminance electroretinograms (ERGs) were recorded to explore retinal responses with the different spectral compositions. In our special colony of pigmented guinea pigs, characterized by residual hyperopia, spontaneous myopia and poor emmetropization, red light induced early thinning of the choroid and relative myopia, compared to white light. Effects of red light could not be suppressed if positive spectacle lenses were worn. ERGs showed that red light failed to elicit robust retinal responses. Blue light inhibited axial eye growth, even when animals were reared with negative lenses. Intensity-matched blue and white light elicited similar a-waves but different b-waves, suggesting that the wavelength of light affects visual control of eye growth through different processing in the inner retina. We hypothesize that blue light might stimulate preferentially the ON pathway to inhibit myopia induced by negative lenses, at least in guinea pigs.

Social Behaviour in a Colony of Domestic Guinea Pigs: Aggression and Dominance

Social behaviour, particularly dominance behaviour, in a colony of domestic guinea pigs was investigated. Observations were of four different types, (1) daily observations on the whole group; (2) interactions between pairs of ♂♂ (in all possible combinations) were recorded when competing over a single water source; (3) interactions between all the ♂♂ in the group observed together at a single water source; (4) as (2) but in the absence of water, in order to observe fighting. It was hoped that the study would demonstrate the extent to which a hierarchial structure, if one such existed, was consistent in different social contexts.

Hallazgo de Panstrongylus rufotuberculatus (Champion, 1899) (Hemiptera, Reduviidae, Triatominae) en ambiente domiciliario en la Región Piura, Perú

Panstrongylus rufotuberculatus is widely distributed in Central and South America. In Peru, it has been found in Tumbes, Piura, and Cuzco. The authors report the presence of P. rufotuberculatus in Chirinos-La Pareja, Suyo district, Ayabaca Province, Piura Region, Peru. Twenty-eight specimens were collected in two of 15 dwellings: three 2nd instar, four 3rd instar, two 4th instar, and eight 5th instar nymphs, three male and eight female, in an intra-domiciliary colony of guinea pigs (Cavia porcellus, raised indoors as a source of diet protein) and beds and bedroom walls. None of the fecal samples were naturally infected with Trypanosoma cruzi. This is the first report of synanthropic presence of P. rufotuberculatus in the region. The finding emphasizes the need for careful entomological and epidemiological surveillance of this and other triatomine species in the Region.

Development of a surgical approach for telemetering guinea pigs as a model for screening QT interval effects

Introduction Identifying a compound's risk of potentially producing Torsade de Pointes (TdP)/QT interval prolongation has become a goal early within the drug development process. Our aim was to develop a surgical approach for instrumenting guinea pigs for collecting ECG data. Methods Male Dunkin Hartley guinea pigs (386–661 g) were surgically implanted with telemetry transducers for the measurement of lead II ECG and arterial blood pressure. Using strict aseptic techniques and isofluorane anaesthesia (0.5–5.0%), one of the three implantation procedures was used. In Phase I the animals were either implanted intraperitoneally (abdominal aorta cannulated) or subcutaneously (carotid artery cannulated). In Phase II all animals were implanted subcutaneously and the subcutaneous pocket formed either with a single incision, as in Phase I, or a double incision. Results Phase I—During intraperitoneal implantation, rupture of the aorta occurred in 50% of the animals. The remaining animals were terminated between 2 and 14 days postsurgery on human grounds. All of the animals implanted subcutaneously survived the surgical procedure and the following 28 days. Skin thinning over the implant occurred in 25% of the animals in weeks 5–6. Phase II—Following single incision subcutaneous implantation 72% of the animals were terminated within the 28-day postsurgery due to skin rupture over the implant body, with only 22% of the animals viable after 28 days. Following double incision subcutaneous implantation 86% of animals were viable after 28 days and thus the recommended method for implantation. Discussion The improvements to the surgical approach have improved survival rates and increased the potential for robust, long term use of telemetered guinea pig colonies for screening for QT prolonging potential and additional cardiovascular assessment in vivo.

α-Mannosidosis in the guinea pig: cloning of the lysosomal α-mannosidase cDNA and identification of a missense mutation causing α-mannosidosis

α-Mannosidosis is a lysosomal storage disorder caused by deficient activity of the lysosomal α-mannosidase. We report here the sequencing and expression of the lysosomal α-mannosidase cDNA from normal and α-mannosidosis guinea pigs. The amino acid sequence of the guinea pig enzyme displayed 82–85% identity to the lysosomal α-mannosidase in other mammals. The cDNA of the α-mannosidosis guinea pig contained a missense mutation, 679C>T, leading to substitution of arginine by tryptophan at amino acid position 227 (R227W). The R227W allele segregated with the α-mannosidosis genotype in the guinea pig colony and introduction of R227W into the wild-type sequence eliminated the production of recombinant α-mannosidase activity in heterologous expression studies. Furthermore, the guinea pig mutation has been found in human patients. Our results strongly indicate that the 679C>T mutation causes α-mannosidosis and suggest that the guinea pig will be an excellent model for investigation of pathogenesis and evaluation of therapeutic strategies for human α-mannosidosis.

Establishment of specific pathogen-free guinea-pig colonies using limited-flora guinea-pigs associated with conventional guinea-pig flora, and monitoring of their cecal flora.

Six groups of limited flora (LF) Hartley guinea-pigs were produced by inoculation of hysterectomy-derived GF guinea-pigs with various combinations of cecal bacteria of conventional (CV) guinea-pigs to determine the effective bacterial cocktails for the establishment of a specific pathogen free (SPF) colony. Bifidobacterium magnum (Bif) isolated from CV guinea-pigs was used for pretreatment. The mortality of LF guinea-pigs inoculated with only Bif was 75%, and that of those inoculated with Bif plus chloroform-treated cecal suspension (CHF) or Bif plus CHF plus 32 isolates from CV guinea-pigs was 40 to 66.7%. These three groups were in an unhealthy condition with mucoid enteritis-like diarrhea. However, the mortality of LF guinea-pigs inoculated with the anaerobic growth on EG plates injected with 10(-5) dilution of cecal contents (CF) or inoculated with Bif plus CF was 6.3 and 15%, respectively. These latter two groups of LF guinea-pigs were transferred to separate barrier rooms and some of the LF guinea-pigs were maintained in isolators as a source of intestinal flora for SPF guinea-pigs. The composition of cecal flora of LF guinea-pigs was stable for a long time, and bacteroidaceae and peptococcaceae were maintained as predominant components. The basic composition of the cecal flora of SPF guinea-pigs originated from LF guinea-pigs, which consists mainly of the anaerobic bacteria, was not changed over a long period, and the flora composition became similar to that in CV guinea-pigs. Guinea-pig-specific pathogens from the SPF colonies were not detected during experiments.

Serological relationship of some V-factor dependent Pasteurellaceae (Haemophilus sp.) from guineapigs and rabbits.

Culture of guinea pig and rabbit respiratory tracts for bacteria using X- (haemin) and V- (NAD) factor in agar media detected infection by V-factor dependent Pasteurellaceae (Haemophilus sp.) in three colonies of guinea pigs and a group of rabbits. The 12 Haemophilus strains comprised three API NH codes classed as Haemophilus parainfluenzae and two codes classed as Haemophilus aphrophilus/paraphrophilus. Six cell wall lipid profiles were detected, but these were not related to API NH codes. Both bacteriological properties were used to select strains for serological studies but any relationship between bacteriological and serological properties of the Haemophilus strains was not evident. Varying serological relationships occurred between the newly isolated Haemophilus strains, [Pasteurella] pneumotropica NCTC 8284 and Haemophilus strains previously isolated from rats.

Typhlitis caused by intestinal Serpulina-like bacteria in domestic guinea pigs (Cavia porcellus).

Between January 1992 and December 1996, Serpulina-like bacteria were demonstrated in intestinal tract lesions from 37 of 88 guinea pigs submitted to the University of Ghent in Ghent, Belgium, for necropsy because of disease and death from different unknown causes. All infected animals had a history of sudden death with minimal introductory clinical signs. Occasionally, they produced yellow, slimy feces or showed nervous signs, but the condition always had a fatal outcome within 24 h. When larger colonies of guinea pigs were involved, the disease spread very rapidly unless treatment with ronidazole was initiated. Lesions consisted of a catarrhal or hemorrhagic inflammation of the colon and cecum (typhlitis). Electron microscopy demonstrated the presence of large numbers of Serpulina-like organisms adhering to the cecal mucosae of these animals. Attempts to isolate the agents failed. The organisms did not stain by an immunofluorescence technique for the detection of Serpulina hyodysenteriae. The present data provide evidence that intestinal Serpulina-like organisms can be important as a cause of disease in guinea pigs.

Intraperitoneal insemination of the guinea pig with synchronized estrus induced by progesterone implant.

Female guinea pigs with synchronized ovulation by means of implantation of progesterone-filled tubing (P-tube) followed by a progesterone injection, were inseminated by intraperitoneal injection with sperm suspension. First, to obtain the optimum conditions for insemination, the females were inseminated singly over the range of 1-10 x 10(7) spermatozoa before and after the synchronized ovulation. The incidence of conception and implantation was 100% in the females given more than 5 x 10(7)/animal at 9:00 h on the 5th day after removal of the P-tube. Second, the reproductive ability of the inseminated females under this optimal condition was observed throughout the pregnancy to delivery. Inseminated females had a mean +/- S.D. gestation period of 68.7 +/- 0.5 days, a litter size of 2.8 +/- 0.6 pups and body weight of 110 +/- 14 g. These data were comparable to those of naturally-mated females. Our findings suggest that the artificial insemination by intraperitoneal injection in combination with the synchronized estrus technique is very useful for production control in a small colony of guinea pigs.

Influence of Feeding Hay on the Alopecia of Breeding Guinea Pigs

Animals with partial alopecia were seen frequently in a breeding colony of guinea pigs. No pathologic aetiology could be determined. An influence of nutrition on the density of the hair coat was considered. Breeding groups were fed one of the commercial guinea pig diets of differing composition, with or without the addition of hay. Observation occurred over a period of months and the quality of the hair coat was evaluated periodically using a semi-quantitative scoring system. More extensive and more frequent fur defects were found is guinea pigs receiving a breeding diet with a high content of crude protein (23%) and a low level of crude fibre (12%), offered hay only restrictively compared with animals receiving a diet with a lower content of crude protein (15.5%) and a higher level of crude fibre (19.5%), offered the same amount of hay. The amount of hay offered is of paramount importance. Animals fed only the diet with the higher level of crude fibre (19.5%), according to the manufacturer's instructions as a complete food, without the addition of hay, showed a less dense hair coat within 4 weeks. In our colony a group of five breeding animals and their young required 200 g of hay daily in order to improve their hair coat quality to normal. Conversely, animals receiving less hay had progressively deteriorating hair coat density. Not only the amount of hay offered, but also the accessibility for all animals plays a role in preventing alopecia in guinea pigs. In larger cages (twice the usual ground surface area) fur defects were seen when the same amount of hay (200 g) was offered in only one central area, rather than spread out evenly throughout the cage. Hair loss was observed to be the result of trichophagia between adult animals kept in the same cage. The need for crude fibre of breeding animals does not appear to be completely met by pellets rich in fibre segments.

Ivermectin treatment of a colony of guineapigs infested with fur mite (Chirodiscoides caviae).

Ivermectin was used for treating a breeding colony of guinea pigs heavily infested with fur mite Chirodiscoides caviae. In preliminary experiments on different dosages and routes of administration, spraying with diluted Ivomec (ivermectin 0.2 mg/ml) as well as applying undiluted ivermectin (10 mg/ml) drops on the fur proved effective and practical. The breeding colony was treated with diluted ivermectin aerosol and retreated two weeks later with undiluted ivermectin drops applied to the coat. After 3 months neither mites nor mite eggs were observed on microscopic examination. Two-and-a-half years later, the guinea pigs are still free of mites.

Eficácia de diferentes tratamentos em cobaias (Cavia porcellus) infestadas por Chirodiscoides caviae

Para um melhor controle sanitário das colônias de cobaias, determinou-se a presença e identificação de ectoparasitos, bem como a porcentagem de eficácia dos ectoparasiticidas mais comumente utilizados no controle de ácaros. Numa colônia de cobaias foi detectado alto grau de infestação, 314 ácaros/cm2 de pêlo. As cobaias infestadas foram submetidas a tratamentos com Cipermetrina high-cis (0,1%), Triclorfon (0,1%), Malation (0,2%) e Monossulfiram (12,5%). Os produtos testados apresentaram alta eficácia.