Veterinary Research Forum

Abstract China's burgeoning animal husbandry sector has witnessed a notable expansion in goose farming. Among the various health challenges, a novel goose astrovirus (GoAstV) has emerged as a significant threat to the industry, necessitating prompt detection strategies to mitigate its economic impact. This research introduces a novel detection approach using real-time fluorescence-based reverse transcription recombinase-aided amplification (RT-RAA), offering a rapid and reliable method for GoAstV identification. We meticulously designed specific primers and probes, and optimized the RT-RAA reaction conditions. The assay's specificity, sensitivity, repeatability, and clinical efficacy were rigorously assessed. Our method achieves detection within a swift 26-min window at a constant temperature of 39.00 ˚C, boasting a detection threshold as low as 1.19 × 10² copies per μL. Notably, the assay exhibited no cross-reactivity with closely related viruses, including Newcastle disease virus, avian influenza virus H9 subtype, goose circovirus, goose parvovirus, duck Tembusu virus, and avian adenovirus type 4. Validation through testing of 40 clinical samples confirmed a 100% agreement with pre-existing data. The study's outcomes underscore the high specificity, sensitivity, and operational simplicity of the developed RT-RAA assay, positioning it as an ideal candidate for the rapid and on-site detection of GoAstV.

Abstract Bovine subclinical mastitis represents a major cause of severe economic losses in dairy farms. This research aimed to detect the antimicrobial resistance trends of Staphylococcus aureus and to determine the presence of mecA, mphC, lnuA, tetK and tetL antimicrobial resistance genes in raw bulk milk in the period between December 2023 and February 2024. One hundred raw bulk cow milk samples were gathered from different dairy farms in Egypt. The prevalence of subclinical bovine mastitis was 65.00% using California mastitis test. The prevalence of isolated S. aureus was 46.15% via bacterial culturing and all isolates (n = 30) were confirmed via hemolytic activity, catalase and coagulase test, and gram staining followed by polymerase chain reaction targeting nuc1 gene. Antimicrobial sensitivity test was applied on all confirmed S. aureus isolates utilizing the disk diffusion method on Mueller-Hinton agar. The highest resistance was verified for tetracycline at 100% followed by erythromycin and clindamycin at 56.66 and 16.66%, respectively. The highest sensitivity at 100% was verified for amikacin, ampicillin, amoxicillin plus clavulanic acid, ampicillin plus sulbactam, ciprofloxacin, colistin, gentamicin, imipenem, tobramycin, doxycycline and vancomycin. Multidrug resistance was found in 20.00% of the total isolates. Methicillin resistant S. aureus represented by mecA gene was identified in 83.33% of isolates. Macrolides resis­tant S. aureus represented by mphC gene was identified in 16.66% of isolates. Lincosamide resistant S. aureus represented by inuA gene was identified in 66.66% of isolates. Tetracycline resistant S. aureus represented by tetK and tetL genes was detected in 23.33 and 53.33% of isolates, respectively. This study provided antibiotic-resistant S. aureus profiles to dairy farms to avoid treatment failure, adverse effects on animal health and economic impact for the owner of the animal.

Abstract The transmission of Escherichia coli (E. coli) containing virulent genes from animals to humans and the environment poses significant public health challenges. This study aimed to detect the virulence factor of the E. coli heme-utilization gene A (chuA) in E. coli isolated from the feces of apparently healthy horses in the island of Sumbawa, Indonesia. The study utilized 52 fecal samples from a total horse population of 283, calculated using the disease detection formula. Fresh feces were collected immediately after excretion and placed in buffered peptone water for subsequent analysis. The samples were then isolated on eosin methylene blue media and identified using biochemical tests. Identified E. coli strains were further examined for detecting the chuA gene using polymerase chain reaction techniques. The E. coli was successfully isolated and identified in 11 (21.15%) of the 52 collected fecal samples. Polymerase chain reaction analysis detected the chuA gene in 8 (15.38%) E. coli isolates at 279 bp on gel electrophoresis. The close interaction between horses and humans in the island of Sumbawa,  Indonesia, may facilitate the spread of E. coli. Thus, surveillance is needed to employ a One Health approach to monitor E. coli strains encoding the chuA gene and other virulence factors to control their dissemination.

Abstract Pneumonia remains a significant economic burden on the small ruminant industry. Excessive inflammation, oxidative stress, and alterations in copper and zinc can accompany pneumonia. As these micro-nutrients play crucial roles in immune function and anti-oxidant defence, modulating their levels may influence the disease progression. This study aimed to investigate the effects of different therapeutic regimens on copper and zinc status in lambs with pneumonia. Twenty lambs with pneumonia were randomly assigned to four treatment groups: oxytetracycline and tylosin (OT), OT plus vitamin B1 (OTVB1), OT plus vitamin C (OTVC), and OT plus vitamin B1 and vitamin C (OTVB1C). A control group received only distilled water. Blood samples were collected on days 1, 3, 6, and 14 for subsequent assessment of plasma copper and zinc concentrations. While the control group maintained stable levels, the pneumonic groups exhibited varying degrees of changes. Plasma copper concentrations increased significantly in all pneumonic groups compared to the control group throughout the study. The OT and OTVB1C groups had the highest number of lambs with increased copper level. Plasma zinc concentrations decreased significantly in the OT and OTVB1 groups, with the lowest levels in the OTVB1 group on day 3. The OTVC group mirrored the control group with stable levels. The OTVB1C group, compared to the other groups, showed a more persistent reduction. These findings suggest that the effects of the various treatment regimens on plasma copper and zinc levels may be complex and time-dependent.

Abstract Alectoris chukar (AC) is a common model organism in biological research. To understand oogenesis and folliculogenesis mechanisms in bird reproduction, we analyzed the ovarian tissue structure of AC at embryonic and pre-pubertal stages. Fertilized eggs, newborn chicks and juvenile AC were used to study the tissue structure of female gonads. Sections of ovaries were prepared and examined using various histological techniques including Hematoxylin and Eosin, Periodic acid-Schiff and Masson's trichrome. Semi-thin and ultra-thin sections of ovary in newly-hatched chicks were prepared for study by electron microscope. The study revealed asymmetry between the left and right ovaries, with a larger left ovary. The functional left ovary exhibited a cortex and medulla, containing somatic and germ cells, with an increase in germ cell number, size and volume leading to cortex thickening. Meiosis division of germ cells and oocyte formation were observed with pre-follicular cells surrounding them. Electron microscopy revealed mitochondria and desmosome cell junctions in germ cells. Our study provided insights into tissue changes in ovaries and germ cells at different developmental stages of AC embryos, newly-hatched chicks and juvenile AC. The results suggested that cortex thickening and germ cell mitochondria density could be used as hallmarks of healthy AC maturity under normal physiological conditions. Further research should explore the impact of growth factors, hormones and environmental factors to unravel avian ovarian development complexities and improve AC reproductive biology knowledge.

Abstract Clostridial disease causes severe economic losses in livestock by rapidly killing ruminants. Therefore, implementing effective control approaches to prevent this fatal disease is importance. The causative agent of this disease is Clostridium spp. Accurate identification of this microorganism is crucial for effectively managing clostridial diseases in farm. There are conventional methods for detecting the disease, including microbiological and biochemical tests, many of these tests are time-consuming and exhibit low sensitivity. So, this study aims to use conventional and molecular approaches to identify Iranian isolates associated with animal infections. To achieve this, 61 samples were collected from1984 to 2024 and cultured on liver media, and subsequently subjected to microbiological and biochemical tests. For molecular identification, the DNA of isolates was extracted, and the isolates were confirmed by polymerase chain reaction (PCR) using specific primers. The results of the conventional analysis revealed that all Iranian isolates were identified as C. perfringens and its type determined by PCR assay. According to our findings, C. perfringens type A is the most prevalent strain in Iran, which predominantly found in ostriches and bird samples, followed by type D. This study underscores the presence of C. perfringens types across variety hosts and geographic locations in Iran. In conclusion, the combining conventional methods with PCR helps reliably detecting Clostridium spp. This information holds the potential to significantly contribute to the development of preventive strategies against clostridial diseases in Iran.

Abstract This study investigated the antioxidant and apoptotic systems of blue swimmer crabs at various reproductive stages, providing valuable insights into their potential as biological markers, particularly in the polluted Persian Gulf. Our research along the coasts of Hendijan County, Iran, involved capturing live crabs (167 ± 52.07 g), examining their morphological traits and determining their reproductive stages through dissection and histological analysis. Apoptosis was detected using the TUNEL assay (terminal deoxynucleotidyl transferase dUTP nick end labeling), and enzyme activities including superoxide dismutase, catalase and glutathione peroxidase were measured using colorimetric methods. Variations were observed in the abundance of apoptotic cells within the hepatopancreas across reproductive stages. The second stage exhibited the lowest values and the first stage displayed the highest indicating a potential link between reproductive activity and apoptosis. Furthermore, enzymes representing the antioxidant system demonstrated various activities during ovarian development. Notably, the second ovarian stage demonstrated the highest catalase (5.63 mM per g protein) and malondialdehyde (12.14 mM per g protein) activities indicating an elevated response to oxidative stress. Our findings demonstrated that apoptotic cell numbers were fluctuated throughout the reproductive stages in the crabs, with the highest levels observed during the first stage and the lowest during the second stage. Understanding these fluctuations not only aids in distinguishing between reproductive and non-reproductive phases but also offers valuable insights into the broader physiological changes occurring throughout the cycle.

Abstract The pet snake industry in Thailand has seen a significant rise in popularity, with the ball python (Python regius) becoming a frequently kept species. However, respiratory disease poses a notable health concern, and various viral pathogens, including serpentoviruses (formerly classified as nidoviruses), have been implicated. While serpentovirus infections have been reported globally in diverse snake species, no documented cases had previously been identified in Thailand. This case report describes a 9-month-old ball python presenting to the Reptile Science Clinic at the Queen Saovabha Memorial Institute in Bangkok, Thailand, with respiratory distress and emaciation. Despite veterinary intervention, the snake succumbed to the infection within two weeks. Post-mortem examination revealed marked mucus accumulation within the oral cavity and necrotic oral mucosa. Histopathological analysis demonstrated severe catarrhal pneumonia. Molecular investigations confirmed the presence of serpentovirus in the lung tissue of the affected python, with subsequent sequence analysis revealing close homology to known serpentoviruses in ball pythons. This report documents the first confirmed case of serpentovirus infection in a pet snake in Thailand.