Search Results (43)

Guinea pigs used in research may experience inappetence or decreased intestinal motility, which can significantly compromise their welfare. This study evaluates the use of mirtazapine on appetite and intestinal motility in guinea pigs. An initial pharmacokinetics and efficacy study was performed using healthy male guinea pigs administered mirtazapine at 1.88, 3.75, or 7.5 mg orally once daily for four days (n = 6), in a crossover design where all animals received all doses. Body, feed, and fecal weights were taken daily for 4 days. There were no significant differences in weight gains, feed intake, or fecal output as compared to guinea pigs given saline only (n = 3). Blood was collected under anesthesia at 0, 0.5, 1, 2, 8, 12, and 24 h post-administration. Pharmacokinetic analysis completed after the first dose showed peak plasma levels at 30 min, then falling below the limit of detection between 8 h and 12 h at all doses. Based on the pharmacokinetic profile, a follow-up study was performed in another set of healthy male guinea pigs with every 8 h dosing at 1.88 mg orally for 5 days (n = 6). There was a significant increase in feed intake during mirtazapine administration as compared to baseline intake, but no significant difference in weight gains. This study shows that mirtazapine can be used as an appetite stimulant in guinea pigs but must be dosed at least every eight hours to be effective. Full article

With the increase in keeping exotic companion mammals as pets, concerns about antimicrobial resistance (AMR) and its impact on animal and human health are growing. Guinea pigs, a popular pet in Hong Kong and globally, have limited studies regarding antimicrobial culture and sensitivity results. We reviewed bacteriologic and antimicrobial sensitivity results from clinically ill pet guinea pigs from 2019 to 2023 using data from the City University Veterinary Diagnostic Laboratory. Of the 234 clinical samples from 22 veterinary clinics in Hong Kong, 134 (57.3%) showed positive bacterial growth, of which 23 (17.2%) showed mixed bacterial growth. In total, 156 bacterial isolates were identified. Gram-positive bacteria (n = 104, 66.7%) were most commonly recovered, representing 25 bacterial species, most commonly Streptococcus spp., Staphylococcus spp., and Corynebacterium spp. The majority of positive samples were from the integument (43.6%) and urinary tract (33.8%). A total of 85.9% of all isolates were resistant to at least one antimicrobial agent, with over 40% of isolates exhibiting resistance to three or more antimicrobial agents, and 27.6% were multidrug resistant (resistant to at least one agent in three or more antimicrobial classes). High resistance rates were observed for penicillin (45.6%), gentamicin (43.7%), doxycycline (42.1%), and azithromycin (36.3%). In contrast, isolates were highly susceptible to ceftazidime (84.1%), chloramphenicol (82.6%), ciprofloxacin (72.7%), and marbofloxacin (72.2%). These findings highlight the high frequency of AMR in this population of clinically ill pet guinea pigs in Hong Kong and the need for informed and judicious antimicrobial use. Full article

The efficiency of in vitro maturation (IVM) in Cavia porcellus remains suboptimal compared to other species. This study aimed to characterize the morphological and functional quality of oocytes based on the stage of the estrous cycle and the classification of the cumulus–oocyte complexes (COCs) from which they were derived. A total of 744 oocytes were recovered postmortem from females in the diestrus and periovulatory phases. Oocytes were evaluated for metabolic activity, lipid distribution, apoptosis, nuclear maturation, and diameter. Oocytes collected during diestrus exhibited larger diameters and more homogeneous lipid distribution, particularly in oocytes from Type A COCs. In contrast, a higher proportion of BCB+ oocytes and reduced rates of early apoptosis were observed during the periovulatory stage, suggesting enhanced metabolic competence. Nuclear maturation rates varied with both cycle stage and COC classification, with oocytes from Type A COCs showing higher maturation rates in diestrus. These findings indicate that both intrinsic (e.g., morphological quality) and extrinsic (e.g., estrous cycle stage) factors modulated oocyte competence. Selecting oocytes based on integrated morphological and physiological criteria may improve the efficiency of IVM protocols in this species. Full article

Gestational chronic hypoxia impacts prenatal development, leading to fetal growth restriction (FGR), defined as the fetus’s failure to reach its genetic growth potential. Postnatal hypoxia in the cerebral tissue can induce a redox imbalance and mitochondrial dysfunction, consequently increasing neuronal death. However, these data cannot necessarily be extrapolated to prenatal hypoxia. In this regard, this study aims to describe the effect of gestational hypoxia on redox balance and apoptosis cell death mechanisms in the prefrontal cortex of guinea pigs. Ten Guinea pig (Cavia porcellus) pregnant dams were utilized in this study; five gestated in normoxia (Nx; three newborn males, and two females) and five gestated under chronic hypobaric hypoxia (Hx; two newborn males, and three females). We monitored the pregnancies by ultrasound examinations from gestational days 20 to 65 (term ~ 70). At birth, pups were euthanized, and the fetal brain was collected for cellular redox measurement, mitochondrial enzyme expression, and apoptosis assay. Gestation under hypoxia induced an imbalance in the expression of anti- and pro-oxidant enzymes, resulting in increased oxidative stress. Additionally, a decrease in cytochrome I and III expression and neuronal density in the neonatal prefrontal cortex was observed. Finally, DNA fragmentation was increased by the TUNEL assay in the brain tissue of newborns gestated under chronic hypoxia. Our findings demonstrate the association of gestational hypoxia with oxidative stress and neuronal death in newborns, which may predispose to neuronal dysfunction in adulthood. Full article

Mammary tumors occur in female and male guinea pigs. However, published data on their histology and sex predispositions are limited. Histologically, we examined proliferative mammary lesions of 69 female and 48 male pet guinea pigs. Lobular hyperplasia was observed only in females (n = 50). Benign tumors included simple adenomas (n = 20), adenolipomas (n = 3) and intraductal papillary adenomas (n = 5). All except two intraductal papillary adenomas occurred in females. Most malignancies were tubulopapillary and solid carcinomas (n = 54), and intraductal papillary carcinomas (n = 13). These were diagnosed more frequently in male (n = 41) than in female (n = 26) guinea pigs. The carcinomas of males had higher mitotic counts than those of females (p = 0.05). Three carcinosarcomas developed in adenolipoma, and one arose in adenoma. Results show that the mammary tumor classification of dogs and cats can be applied to guinea pigs. However, some tumors (adenolipoma, metaplastic carcinoma) are unique to guinea pigs and shared with laboratory rodents and humans, respectively. Benign tumors may undergo malignant progression. Male guinea pigs appear predisposed to ductal-associated and malignant tumors. Data suggest that male guinea pigs represent an animal model for human male breast cancer. Full article

Sustainable fertilization using local resources such as manure is crucial for soil health. This study evaluated the potential of guinea pig manure to replace mineral fertilizers in hard yellow maize (hybrid INIA 619) under Peruvian coastal conditions. A split-plot design tested four doses of guinea pig manure (0, 2, 5, 10 t⋅ha⁻¹) and four levels of mineral fertilization (0%, 50%, 75%, 100%). The study assessed plant height, ear characteristics, yield, and nutritional quality parameters. The results indicated that 100% mineral fertilization led to the highest plant height (229.67 cm) and grain weight (141.8 g). Yields of 9.19 and 9.08 t⋅ha⁻¹ were achieved with 5 and 10 t⋅ha⁻¹ of manure, while 50% mineral fertilization gave 8.8 t⋅ha⁻¹, similar to the full dose (8.7 t⋅ha⁻¹). The protein content was highest with 10 t⋅ha⁻¹ of manure combined with mineral fertilization. However, no significant differences were found between the 50%, 75%, and 100% mineral fertilizer doses. In conclusion, applying guinea pig manure improved nutrient use efficiency, yield, and grain protein quality in maize, reducing the need for mineral fertilizers by up to 50%. This provides a sustainable fertilization strategy for agricultural systems. Full article

Research on the welfare of pet guinea pigs and connections between their behaviour and husbandry practices is scarce. Through an online survey among 1181 German-speaking guinea pig caretakers, we investigated husbandry practices (including social composition, housing type, free roaming, enrichment, and feeding), human–animal interactions, and guinea pig behaviour. Most participating caretakers seemed attentive to their animals’ needs and welfare, as shown by the prevalence of self-built enclosures (42.8%) and fenced floor areas (21.1%), with various enrichment and furnishings, and mostly balanced nutrition. Husbandry practices that can negatively impact welfare, such as individual housing and no constant access to hay, were observed for 7.5% and 0.4% of the animals, respectively. Eating and resting next to conspecifics and locomotor play occurred several times per day in 87.6%, 48.1%, and 19.9% of animals, respectively. Biting, running up and down and bar chewing were rare (several times per day in 0.4%, 2.9%, and 0.7% of animals, respectively). We found significant associations of guinea pig behaviour with human–animal interactions and housing conditions. For instance, affiliative behaviour and locomotor play and use of enrichment were more frequently reported in the case of more frequent positive human–animal interactions and food enrichment. Our results provide additional knowledge to support consultations on behaviour and husbandry practices. Full article

Recently, interest in developing functional foods that promote health has grown significantly. This study aimed to evaluate the feasibility of microencapsulating guinea pig blood erythrocytes by vacuum drying and incorporating them into gummies fortified with tumbo juice. Physicochemical analysis (proximate analysis, iron content, color, pH, soluble solids, and particle size) and functional group analysis by Fourier transform infrared spectrophotometry were performed on three formulations of gummy candy with added encapsulated erythrocytes from guinea pig blood (EEGPB): F1 (4% EEGPB), F2 (5% EEGPB), and F3 (6% EEGPB). The results showed a significant decrease in the moisture content (52.02% in F1 to 43.27% in F3) and increases in protein (11.44% in F3) and iron (2.63 mg Fe/g in F3) contents when higher EEGPB levels were used. Sensory evaluation revealed that F3 was the most acceptable formulation in terms of taste, aroma, and texture, with no significant differences in color. FTIR analysis confirmed physical incorporation with no chemical interactions between ingredients. These results demonstrate that the encapsulation of erythrocytes by vacuum drying not only preserves the bioactive compounds but also improves the organoleptic properties of the gummies, making them an attractive product for consumers. In conclusion, this technique is effective for fortifying functional foods and has potential application in other food products. This approach represents a significant advance in the development of innovative functional foods. Full article

In the last decade, the production of guinea pig meat in Andean countries has increased due to the growing number of consumers of this meat. Objective: To evaluate the effect of including different doses (0.50, 1.00, and 1.50 mL) of agro-industrial substrates (molasses distillery waste) fermented with lactic acid bacteria and yeasts on productive performance, hematological profile, relative weight changes in digestive tract organs, and changes in the intestinal microbiota in guinea pigs (Cavia porcellus). Materials: A total of 300 guinea pigs, Kuri breed, aged 20 days and weighing 330 g, were distributed into 10 groups of 30 animals each. Ctrl, Control. La, substrate fermented with Lactobacillus acidophilus (8.1 × 10⁷ CFU/mL). Kf, substrate fermented with Kluyveromyces fragilis (7.4 × 10⁶ CFU/mL). La + Kf, substrate fermented with bacteria and yeasts; the evaluated doses were 0.50, 1.00, and 1.50 mL/animal. The indicators evaluated in the study included weight gain, health, hematological profile, relative weight of digestive tract organs, and changes in the intestinal microbiota. Results: The parameters evaluated were toxicity, productive parameters, occurrence of diarrhea and mortality, and blood profile. The results showed a significant increase in the weight of the animals consuming probiotics, especially at higher doses. Additionally, an improvement in the intestinal microbiota was observed, with an increase in beneficial bacteria such as Lactobacillus and a decrease in pathogenic bacteria. Probiotics also influenced the hematological parameters and the weight of digestive tract organs, suggesting a positive effect on the overall health of the animals. Conclusions: Supplementation with probiotics proved to be a promising strategy for improving productive performance and intestinal health in guinea pigs. Supplementation with L. acidophilus and K. fragilis significantly enhances guinea pig growth and modulates the intestinal microbiota. The combination of strains and appropriate doses maximizes benefits. These results promise applications in animal production, requiring further studies to confirm their efficacy in other species and developmental stages. Full article

The objective of this work was to ascertain the nutritive value of six concentrate feedstuffs commonly used in guinea pig feed manufacturing through the substitution method. Six test diets were obtained by replacing the corresponding basal mixture with 40% corn, 50% barley, 45% wheat bran, 35% soybean meal, 30% pigeon pea, or 30% Leucaena leaf meal. Sixty-three guinea pigs were randomly assigned to one of the nine experimental diets (three basal diets and six test diets, with seven animals per diet). The animals were housed in individual cages and provided with feed and water ad libitum. Following a ten-day adaptation period, the feed intake and faeces excretion were monitored for a further five days. The digestible energy content, expressed as kcal/kg dry matter (±standard error), was 3857 ± 83 for corn, 3454 ± 68 for barley, 2911 ± 110 for wheat bran, 3855 ± 81 for soybean meal, 3105 ± 79 for pigeon pea, and 2972 ± 72 for Leucaena leaf meal. The apparent total tract digestibility of crude protein, expressed as % (±standard error) was 73.8 ± 4.9 for corn, 69.5 ± 4.6 for barley, 76.4 ± 3.6 for wheat bran, 88.4 ± 1.0 for soybean meal, 62.1 ± 1.9 for pigeon pea, and 68.0 ± 1.8 for Leucaena leaf meal. Further research is required to increase knowledge about these and other feedstuffs for guinea pigs. Full article

Guinea pigs (Cavia porcellus) are used for interactive activities in zoos; therefore, it is important to investigate their welfare. This study aimed to evaluate the validity of measuring the guinea pigs’ body temperature of guinea pigs through the ear canal and investigate the relationship among changes in the expression of negative behavior, changes in body temperature, and changes in salivary cortisol concentration, and examine the effects of different interactive activities. In the normal interactive activities performed at the site, the decreased body temperature of pigs was observed over time. In contrast, increased body temperature was observed in excessive interactive activities, which are not recommended. Among the negative behaviors, “Head turning” and “Locomotion” increased significantly in excessive interactions compared to normal interactions, but “Head tossing” decreased significantly over time in both types of interactions. “Freezing” was observed only in excessive interactions. Salivary cortisol concentration increased significantly for all activities. Investigating the relationship between the individual expression of negative behavior and changes in body temperature and changes cortisol level made it possible to uncover the potential for inferring an animal’s physiological state. Combining ear temperature monitoring and behavioral observation during zoo interaction activities is recommended as an ethical and scientifically supported practice. Full article

Biological variation (BV) describes the physiological random fluctuation around a homeostatic set point, which is a characteristic of all blood measurands (analytes). That variation may impact the clinical relevance of the changes that are observed in the serial results for an individual. Biological variation is represented mathematically by the coefficient of variation (CV) and occurs within each individual (CV_I) and between individuals in a population (CV_G). Biological variation data can be used to assess whether population-based reference or subject-based reference intervals should be used for the interpretation of laboratory results through the calculation of the index of individuality (IoI). This study aimed to determine the biological variations, calculate the IoI and reference change values (RCV) of clinical chemistry analytes in an outbred strain colony of Hartley guinea pigs (GPs), and set the quality specifications for clinical chemistry analytes. Blood was collected from 16 healthy adult laboratory colony GPs via jugular venipuncture at weekly intervals over six weeks. All the samples were frozen and analyzed in a single run. Analytical, CV_I, and CV_G biological variations, together with the IoI and RCV, were calculated for each measurand. Based on the estimated BV, the calculated IoI was low for glucose, so individual reference intervals (RCV) should be used. The majority of the measurands should be interpreted using both population-based and subject-based reference intervals as the IoIs were intermediate. Full article

Organophosphorus insecticides (OPs), acting as serine phosphorylating agents in acetylcholinesterase (AChE), are highly effective neurotoxic insecticides. In our previous research, we found that six herbivorous pests and four ladybirds howed significantly higher AChE LC50 values than seven parasitoids and a predator (Epistrophe balteate), and that there was a significant correlation with the corresponding bimolecular rate constant (Ki) value. The Ki value of pests was much smaller than that of natural enemies and had a higher LC50 value.Then, we speculated that the low sensitivity of the pest AChE to OPs may be associated with its higher recovery and lower aging ability. In this work, the I50 and I90 were calculated, to determine the sensibility of AChE in ten representative species, including Plutella xylostella, Prodenia litura, Musca domestica, and Cavia porcellus, to paraoxon and malaoxon. The enzyme activities were measured at various time points, and kinetic calculations were used to obtain their spontaneous reactivation (Ks) and aging (Ka) constants, which were comprehensively compared. We conclude that the Ka and Ks of the AChE inhibited by OPs showed primarily species-specific correlations, and little correlation with the sensitivity to OPs. The differences in the AChE sensitivity to paraoxon among the ten species were much greater than in the sensitivity to malaoxon. Compared to paraoxon, malaoxon was more selective for Cavia porcellus. Coleoptera insects showed a stronger dephosphorylation ability than other insect groups. The recovery ability of phospho-AChE was stronger in mammals than in insects, which could be related to the low sensitivity of the AChE site of action to OPs. The Ka of the AChE inhibited by malaoxon was larger than that inhibited by paraoxon with the corresponding biomaterials, indicating that the OP type had a substantial relationship with the Ka of the AChE. We further discovered that, when insects were inhibited by OP, the tendency of AChE to undergo aging was greater than that of dephosphorylation. Overall, the study provides valuable information on the action mechanism of various OPs on AChE in several species, which could be used to further research into AChE and the potential dangers that organophosphates pose to animals. Full article

Based on the qualities of Ulmo honey (Eucryphia cordifolia), a medical-grade honey (Ulmoplus^®) has been developed. Relevant to this, the use of copper represents an emerging therapy for the treatment of wounds. Therefore, the aim of this study was to see how this medical-grade honey with copper nanoparticles (CuNPs) helped to heal infected or non-infected wounds. Twenty-four guinea pigs (Cavia porcellus) were divided into four groups for phase 1 (without and with infection, U + F₁ and U + F₂), and two groups for phase 2 (selected formulation, without and with infection, U + F₂NI and U + F₂I). Bacteriological and histopathological studies, collagen fibers content evaluation, and stereological analysis were performed. The selected formulation displayed the same antibacterial potency as Ulmoplus^®, indicating that this medical-grade honey by itself can be used as an antibacterial agent. However, the evaluation of collagen content demonstrated a significant increase in fibroblast and type III collagen fibers for infected and uninfected groups, which correlated with the histopathological study. Therefore, it is correct to affirm that adding CuNPs to Ulmoplus^® improved the maturation of collagen fibers. Finally, polymorphonuclear cells presented similar values between experimental groups, which would indicate that the formulation under study was able to regulate the inflammatory process despite their infectious condition. Full article

Sperm morphology can predict the reproductive male fertilizing potential. This study aimed to determine the morphological and morphometric spermatozoa characteristics from guinea pigs subjected to different photoperiodic stimulation. Thirty F1 guinea pigs were randomly assigned to three photoperiodic treatments: FT1 (photoperiod with 10 Light/14 Dark LED light), FT2 (photoperiod with 10L/14D sunlight), and FT0 (room without direct light source). At 107 ± 9.8 days of age, sperm concentration and motility were higher in the FT0 and FT1 groups (p < 0.05); furthermore, there were no differences in nucleus length and ellipticity between the FT0 and FT1 groups, but the sperm of the FT1 group was higher in perimeter and nuclear area, while that of the FT0 group was higher in roughness, regularity, midpiece length, and tail (p < 0.01). Expanding acrosome (Type 2) was more frequent in the FT2 group, but there was variation in head measurements between all morphological categories. Pregnancy rate, calving age, and mating age were higher in the FT0 group; meanwhile, the FT1 group initiated successful matings earlier (p < 0.01). The FT0 group had a higher fertility rate, and the age of mating and first calving were earlier in the FT1 group than the FT0 group, but no pregnancies were reported for the FT2 group. Photoperiodic stimulation can increase the morphometric dimensions of guinea pig spermatozoa, favoring the reproductive characteristics, but sunlight could reduce their size due to heat stress. Full article