Objective This study aims to establish a non-puerperal mastitis (NPM) rat model by simulating hyperprolactinemia and immune-inflammatory states, and to evaluate its local inflammatory characteristics in the mammary gland, thereby laying the foundation for research on the diagnosis and treatment of this clinically challenging disease. Methods Twelve SPF-grade Wistar female rats were evenly divided into a control group and a model group. During the experiment, the control group received no experimental treatment or medication. The model group received daily subcutaneous injections of 100 mg/kg metoclopramide hydrochloride for 7 consecutive days. Serum prolactin (PRL) levels were measured using ELISA on the 10th, 20th, and 30th days after the first injection. After 7 days of injections, 200 μL of lactating SD rat milk was mixed with 200 μL of complete Freund's adjuvant to prepare an oil-in-water emulsion, which was administered by multiple subcutaneous injections into the back of the Wistar rats for the initial immunization. Seven days after the initial immunization, the emulsion was injected subcutaneously into the third, fourth, and fifth mammary glands for the final immunization. After the final immunization, the rats were observed for 28 days for changes in mammary gland appearance, and the size of mammary nodules was calculated. On the 3rd, 7th, 14th, and 28th days, hematoxylin-eosin (HE) staining was used to analyze mammary tissue morphology. Immunohistochemistry was employed to detect CD138 expression levels. ELISA was used to measure the levels of interleukin (IL)-6, IL-1β, tumor necrosis factor (TNF)-α, and inducible nitric oxide synthase (iNOS) in mammary tissue to comprehensively assess the model. Results Rats in the model group exhibited mammary skin ulceration and foul odor at the ulcer sites. Palpation and ultrasound revealed the formation of mammary nodules. HE staining showed that on the 3rd day after the final immunization, normal ductal and lobular structures in the mammary glands disappeared, with significant infiltration of plasma cells. On the 7th day, ductal dilation, epithelial necrosis and detachment, and pronounced periductal plasma cell and lymphocyte (predominantly T-lymphocytes) infiltration were observed. On the 14th day, there was a proliferation of fibrofatty tissue, small blood vessels, and granulation tissue, with scattered plasma cells in the interstitium. By the 28th day, inflammatory cell infiltration and fibrous tissue proliferation were reduced, with granuloma formation. Serum PRL levels in the model group were significantly increased on the 10th day (P<0.05) and the 20th day (P<0.001). IL-6 and TNF-α levels in mammary tissue were higher in the model group compared to the control group on the 3rd, 7th, 14th, and 28th days (P<0.05). IL-1β levels were higher on the 3rd, 7th, and 14th days compared with the control group (P<0.01) but lower than the control group on the 28th day (P>0.05). iNOS levels were significantly higher on the 7th day after the final immunization (P<0.001). Conclusion A successful NPM model was established in rats, which exhibited typical pathological features such as local mammary masses, abscesses, ulcers, ductal dilation and plasma cell infiltration. This model can serve as a foundation for further research into the diagnosis and treatment of this clinically challenging disease.

Objective To establish a rat model of moderate-to-severe knee osteoarthritis, laying the foundation for studying the pathogenesis of moderate-to-severe knee osteoarthritis and its prevention and treatment methods. Methods Thirty male SD rats were randomly divided into three groups: a sham surgery group, an 8-week model group, and a 20-week model group, with 10 rats in each group. Rats in the 8-week and 20-week model groups underwent surgery to cut the anterior and posterior cruciate ligaments and medial collateral ligament of the right knee joint, and remove the medial and lateral menisci. After surgery, the rats were allowed to move freely. The rats in the sham surgery group had only skin incisions to expose the joint without any surgical treatment. At 8 and 20 weeks post-surgery, Micro-CT scans were performed to analyze the femoral osteoporosis in the rats. After euthanizing the rats, gross observations of the knee joints were made, and the cartilage of the joint surface was scored using the Pelletier scoring system. The knee joints were collected for hematoxylin and eosin (HE) staining and safranin O-fast green staining to observe changes in cartilage morphology. The modified Mankin's scoring system was used to assess the tissue pathology of the joint surface. Immunohistochemical staining was used to detect the expression of type II collagen and matrix metalloproteinase 13 (MMP13), reflecting the anabolic and catabolic metabolism of the knee joint cartilage. Results The knee joint cartilage in the 8-week and 20-week model groups was severely damaged, with Pelletier and modified Mankin's scores significantly higher than those in the sham surgery group (both P<0.01). The Pelletier and modified Mankin's scores in the 20-week model group were significantly higher than those in the 8-week model group (P<0.01). Micro-CT observations revealed irregular joint surfaces, osteophyte formation, and signs of osteoporosis in both the 8-week and 20-week model groups, with the 20-week model group showing more loose bodies around the knee joints. Immunohistochemical staining showed increased expression of MMP13 and decreased expression of type II collagen in the knee joint tissues of the model groups, indicating that the balance of anabolic and catabolic metabolism in the joint cartilage was disrupted. MMP13 increased while type II collagen decreased. Conclusion The surgical method of cutting the anterior and posterior cruciate ligaments and medial collateral ligament and removing the medial and lateral menisci successfully creates a moderate-to-severe knee osteoarthritis model in rats. Imaging examinations reveal osteophytes, osteoporosis, and loose bodies in the knee joints, while pathological observations show a reduction or even disappearance of joint cartilage, with a disruption in the balance of cartilage anabolic and catabolic metabolism.

Objective This study aims to establish a novel hyperglycemic obesity mouse model by utilizing Triacsin C, an inhibitor of acyl-CoA synthetase long-chain family member 1 (ACSL1), combined with a high-fat diet, to simulate the changes in adipose tissue and cardiac function observed in patients with obesity-related type 2 diabetes. Methods Twenty adult SPF-grade male C57BL/6J mice were randomly divided into two groups: the Control group (injected intraperitoneally with citric acid-sodium citrate buffer, Con group) and the TC group (injected intraperitoneally with Triacsin C, TC group). After four consecutive weeks of intraperitoneal injections, both groups were fed high-fat diets. Body weight and glucose tolerance of the mice were assessed every eight weeks. The models were considered successful if fasting blood glucose exceeded 8 mmol/L or blood glucose was above 15 mmol/L two hours after glucose injection. Cardiac function, including ventricular end-diastolic diameter (LVEDD), left ventricular end systolic diameter (LVESD), end-diastolic interventricular septal thickness (EDIVS), left ventricular ejection fraction (LVEF), and left ventricular short-axis fractional shortening (FS), was measured by echocardiography. HE staining was used to detect the changes in epididymal white adipose tissue (WAT) and brown adipose tissue (BAT). Immunofluorescence technology was used to analyze changes in CD31 and UCP1 in BAT. ACSL1 expression in myocardial tissue was tested by Western blotting. Results The fasting blood glucose levels were (8.14±1.43) mmol/L in the Con group and (8.18±0.85) mmol/L in the TC group (P>0.05) , and the 2-hour postprandial blood glucose levels were (19.8±4.01) mmol/L in the Con group and (22.60±3.97) mmol/L in the TC group (P<0.05). This indicated that both groups of diabetic mouse models were successfully established. Compared to the Con group, the TC group showed poor glucose tolerance; significant decreases in LVEDD, LVEF and FS (P<0.05); significant increases in WAT and BAT areas (P<0.05); significant decreases in CD31 and UCP1 expression (P<0.05); and a significant decrease in the expression of ACSL1 in myocardial tissues (P<0.05). Conclusion Compared with the high-fat diet-induced type 2 diabetes model, the new hyperglycemic obesity and cardiac dysfunction mouse model, created by the combination of Triacsin C and a high-fat diet, is feasible and allows for easier observation of brown adipose tissue whitening, insulin resistance and cardiac dysfunction.

Duchenne muscular dystrophy (DMD) is a severe X-linked recessive genetic disorder caused by mutations in the DMD gene, making it one of the most common forms of hereditary muscular dystrophy. The DMD gene, which encodes dystrophin, is the largest known gene in the human genome. Mutations in the DMD gene are highly diverse, including exon deletions, duplications, point mutations, and small insertions or deletions, posing significant challenges for treatment. Currently, there is no cure for DMD, and existing treatment strategies focus primarily on symptom management, which cannot reverse or halt disease progression. Advances in biotechnology position nucleic acid drugs and gene therapies at the forefront of DMD treatment research. These treatments aim to restore dystrophin expression by repairing or replacing mutated genes, thereby improving muscle function or slowing muscle degeneration. Preclinical studies in animal models and early-phase clinical trials demonstrate promising efficacy and offer new hope for DMD patients. This review briefly outlines the pathological mechanisms and genetic characteristics of DMD before delving into recent progress in therapeutic strategies, with a particular focus on nucleic acid drugs (including antisense oligonucleotides for exon skipping therapy and translation readthrough inducers) and gene therapy approaches (including gene replacement therapy and gene editing). The development and application of these therapies not only provide new treatment options for DMD patients, but also offer valuable insights for addressing other genetic disorders. However, numerous challenges impede the clinical translation of DMD treatments. Future studies must optimize existing therapeutic strategies, improve their efficacy and applicability, and explore innovative approaches to deliver more effective and sustainable treatments for DMD patients.

Atmospheric fine particulate matter (particulate matter 2.5,PM_2.5) is a major component of haze, and its potential hazards to human reproductive health have garnered widespread attention. Establishing appropriate animal models is crucial for in-depth research into the reproductive toxicity of PM_2.5 exposure and its underlying mechanisms. This paper, based on recent literature, summarizes current methods for establishing PM_2.5-exposed animal models and the evaluation criteria for reproductive toxicity research. The primary modeling methods for PM_2.5 exposure include whole-body inhalation exposure and intratracheal instillation exposure. While whole-body inhalation exposure effectively simulates real-life human inhalation environments, it requires sophisticated experimental equipment. Conversely, intratracheal instillation exposure is more cost-effective and easier to operate but faces challenges in accurately mimicking the distribution and deposition of PM_2.5 during natural inhalation. Therefore, researchers must carefully weigh these exposure methods to enhance model rigor and achieve the most realistic simulation of human exposure conditions. When summarizing the application evaluation indicators of PM_2.5-induced reproductive toxicity, this review finds that the main indicators of male reproductive toxicity include reduced sperm quality, testicular tissue damage, and hormonal imbalances. For female reproductive toxicity, the primary indicators are reduced ovarian reserve, endocrine dysfunction, endometrial damage, and adverse perinatal reactions. Additionally, this review highlights the need for detailed chemical composition analysis of PM_2.5, exploring the reproductive toxic targets and mechanisms of particles containing different chemical components, such as heavy metals and polycyclic aromatic hydrocarbons. Long-term studies are also necessary to assess the effects of PM_2.5 exposure on reproductive health and transgenerational effects, to predict potential long-term risks for humans. Additionally, interdisciplinary collaboration should be encouraged, involving cooperation between environmental science, toxicology, reproductive medicine, and other disciplines, to comprehensively assess the environmental health risks of PM_2.5 and provide scientific support for the development of integrated prevention and control strategies. This review summarizes animal modeling methods, evaluation criteria, and their applications, providing valuable methodological references for future reproductive toxicity research on PM_2.5.

Sepsis is a multi-organ dysfunction syndrome caused by infection and immune dysfunction, with a high mortality rate. It affects multiple important organs such as the heart, lungs, kidneys, liver, and brain. Establishing corresponding animal models of organ dysfunction syndrome is an essential step in clarifying its pathogenesis, researching potential effective drugs, and evaluating the effectiveness and safety of treatment plans. This article first summarizes classic modeling methods for sepsis related organ injury, including the destruction of intestinal barrier tissue integrity and the implantation of pathogens or toxic drugs. The former mainly includes cecal ligation and puncture, ascending colon stent implantation, and cecal ligation incision. The latter is divided into intraperitoneal injection, intravenous injection, and intratracheal administration based on the clinical infection route being simulated. Cecal ligation and puncture and lipopolysaccharide intraperitoneal injection are the most commonly used methods. Secondly, this article summarizes the common modeling methods and evaluation methods for animal models of sepsis-induced cardiomyopathy, acute lung injury, acute kidney injury, acute liver injury, and brain dysfunction. It points out that almost all organ injuries use classic modeling methods, and different organ injury models have additional modifications according to their different pathogenesis. For example, in addition to the classic modeling methods, lipopolysaccharide instillation in the trachea is more effective in modeling acute lung injury as it better simulates lung barrier dysfunction. Cecal ligation and puncture followed by Pseudomonas instillation in the trachea in a secondary challenge model better represents sepsis-induced acute kidney injury. Intraperitoneal injection of galactosamine is a mature modeling method of sepsis-induced acute liver injury. Intracerebral injection of lipopolysaccharide is a feasible model of sepsis-associated encephalopathy. In addition to the different modeling methods, there are differences in the administration time, dosage and experimental time points according to the different experimental purposes. This article reviews the research progress of animal experimental models for sepsis-induced cardiomyopathy, acute lung injury, acute kidney injury, acute liver injury, and brain dysfunction, aiming to provide a reference for the selection of animal experimental models and optimization of experimental design.

Since the 1970s, the laboratory animal industry in Suzhou has gone through five stages: its inception, emergence, growth, transformation, and scaling up. It began with the manufacturing of caging equipment for laboratory animals, initially by imitation and later through independent innovation. The industry evolved from sporadic factories to clustered enterprises, gradually growing and opening up the export market for caging equipment. In the 21st century, with industrial upgrading and transformation, purification systems and related products began to develop, and industry organizations emerged. As China has modernized, the rise of automation and intelligent production has led to technological innovation in enterprises and the emergence of various outsourcing services in the laboratory animal industry, driving the large-scale development of the industrial chain. After nearly half a century of growth, the laboratory animal industry in Suzhou has formed a complete industrial chain, including the production of laboratory animals, caging equipment, feed and bedding materials, design and construction of laboratory animal facilities, quality testing of laboratory animals and environments, and animal experimentation services. Laboratory animal breeding equipment, the core of the industry, has reached the level of developed countries, and the industry's scale and influence are unmatched in China. Since the 21st century, biopharmaceuticals have become the "No.1 industry" in the development of Suzhou. With government support, the guidance of the local economy, and the assistance from universities and research institutes, the animal experiment outsourcing industry has begun to cluster in Suzhou. The continuous influx of CROs has driven the construction of large-scale laboratory animal facilities, and key research projects have been initiated, significantly enhancing the industry's R&D capabilities. The Suzhou laboratory animal industry has quickly expanded alongside the "No. 1 industry," creating a unique "Suzhou Path" for laboratory animals. Over nearly fifty years, the laboratory animal industry in Suzhou has been essential to the rapid development of the biopharmaceutical industry in Suzhou and China.

Objective To provide reference for further strengthening the management of laboratory animals in Sichuan Province by reviewing and analyzing the results of parasitic and microbial quality inspections of laboratory animals from 2017 to 2023. Methods Sichuan Province has 31 licensed laboratory animal production units, with the main species including mice, rats, guinea pigs, rabbits, dogs, monkeys, and pigs. Sampling inspections and reports were conducted for units with laboratory animal production qualifications in accordance with current national and local standards for laboratory animal classification. The quality inspection results for various laboratory animals in Sichuan Province from 2017 to 2023 were analyzed. Results With the exception of 2018, annual quality inspections of laboratory animals were conducted every year between 2017 and 2023. Mice: In 2017, positive results for helminths, flagellates, Salmonella, murine hepatitis virus antibodies, and murine pneumonia virus antibodies were detected, with a pass rate of only 42.9%. In 2019, Staphylococcus aureus and Klebsiella pneumoniae were detected, with a pass rate of 86.7%. In 2021, Sendai virus antibodies were detected, yielding a pass rate of 85.7%.The pass rate in 2020, 2022, and 2023 was 100%. Rats: In 2017, positive results were found for helminths, mycoplasma antibodies, Staphylococcus aureus, Sendai virus antibodies, murine pneumonia virus antibodies, rat parvovirus RV strain antibodies, rat parvovirus (H-1) strain antibodies, and rat coronavirus antibodies, with a pass rate of 40.0%. In 2019, mycoplasma antibodies, Staphylococcus aureus and Klebsiella pneumoniae were detected, with a pass rate of 35.0%. No positive indicators were detected in 2020. In 2021, Sendai virus antibodies and rat parvovirus RV strain antibodies were detected, with a pass rate of 50.0%. In 2022, positive results for rat parvovirus RV strain antibodies were found, yielding a pass rate of 87.5%. In 2023, Pasteurella pneumotropica and Klebsiella pneumoniae were detected, with a pass rate of 85.7%. Dogs: In 2017 and 2019, the antibody titers for rabies virus and canine distemper virus were below the required standard, with pass rates of 33.3% and 20.0%, respectively. In 2020 and 2022, the pass rate was 100%. Guinea pigs (general grade): In 2019, positive results for Toxoplasma antibodies were detected, with a pass rate of 80.0%. In all other years, the pass rate was 100%. Monkeys: In 2019, positive results for Toxoplasma gondii and rhesus herpesvirus type I antibodies were found, with a pass rate of 87.5%.In 2020 and 2022, rhesus herpesvirus type I antibodies were positively detected, yielding pass rates of 93.3% and 97.5%, respectively. The pass rates in 2021 and 2023 were 100%. Clean guinea pigs, rabbits and pigs all passed the inspection each year. Conclusion Issues related to the parasitic and microbial quality of laboratory animals persist in Sichuan Province. Supervision and sampling inspections have proven to be effective in identifying these issues promptly, serving as a critical measure to ensure the quality of laboratory animals. The results of these inspections offer valuable data to support the healthy development of the laboratory animal industry in Sichuan Province.

Feline coronavirus (FCoV) is classified into two biotypes: feline infectious peritonitis virus (FIPV) and feline enteric coronavirus (FECV). FIPV and FECV might evolve and mutate via genetic recombination and mutation, leading to novel subtypes and variants. This study examined the genomic structure and biological subtyping of FCoV, analyzed the infection characteristics of FIPV and FECV, and investigated the mechanisms of FECV transforming into FIPV. The findings revealed that while their genome structures were fundamentally similar, differences in their ability to efficiently infect monocytes/macrophages significantly influenced their pathogenicity and transmission characteristics, with FIPV exhibiting higher virulence. Moreover, the analysis of the open reading frames (ORF)3/7 as well as the N/S sequences of FIPV indicated that its non-structural proteins were associated with modulation of the host immune system. These proteins enabled immune evasion, leading to more severe disease. The genomic variability of FCoV constitutes an important foundation for studying the pathogenicity and epidemiology of FIPV and FECV, and offers references for virus detection and drug development.

Experimental pigs occupy a crucial position in life sciences research and have been indispensable in advancing the practical application of new clinical technologies and methods. The Da Vinci Surgical Robot System, developed by Intuitive Surgical in the United States, has been widely used across various surgical fields since its approval by the U.S. Food and Drug Administration (FDA) in 2000, and is highly esteemed for its precision and accuracy. With the continuous advancement of surgical robot technology, the skill requirements for medical professionals have also increased. Consequently, surgical skills training has become an essential component of ensuring both surgical safety and effectiveness. This article briefly reviews the current status of Da Vinci surgical robot training, both domestically and internationally, with a focus on the practical application of experimental pigs in domestic Da Vinci surgical robot training. It emphasizes that experimental pigs not only effectively simulate the human surgical environment, enabling trainees to practice in a safe and controlled setting, but also help accelerate the trainees' familiarity with and mastery of the surgical robot. This, in turn, significantly shortens the learning curve, enhances the precision and stability of surgical procedures, and reduces surgical risks. However, the use of experimental animals in surgical robot training also encounters challenges, including limitations caused by the differences between experimental animals and humans, potential ethical concerns, and public opinion pressures. In response to these challenges, the paper proposes suggestions such as improving and enforcing ethical regulations, as well as advancing the development of virtual reality (VR) and augmented reality (AR) technologies. These efforts aim to reduce reliance on experimental animals in surgical training while enhancing training effectiveness, thereby contributing to the innovation and development of Da Vinci surgical robot training models.

Objective To compare the effects of six composite fixatives on paraffin sections of golden hamster retinal tissue, and to optimize the fixation methods for retinal tissue paraffin sections of golden hamsters. Methods Eighteen male SPF grade golden hamsters were taken and randomly divided into six groups of three animals each. After each animal was anesthetized by intraperitoneal injection of sodium pentobarbital, cardiac perfusion was performed using 4% paraformaldehyde, Bouin's, Carnoy, Davidson's, Zenker, and Helly fixatives, respectively. The eye tissues of each animal were taken out to make eye cups and put into the corresponding compound fixative solution for fixation, and then taken out for paraffin embedding after 48 h. The embedded blocks were sliced using microtome, and then stained with hematoxylin and eosin (HE). The morphological characteristics of retinal tissue cells were observed under a light microscope and scored in a double-blind method to statistically analyze the fixation effect and staining quality of various composite fixative solutions. Results Retinal sections fixed with Davidson's fixative exhibited intact morphology without breaks, clear structural layers, well-morphosed nuclei, and tight adhesion between the retina, sclera, and uvea. In contrast, sections fixed with 4% paraformaldehyde, Bouin's, and Carnoy fixatives showed varying degrees of retinal breaks and detachment from the sclera. Sections fixed with Zenker and Helly fixatives demonstrated the poorest quality, characterized by pronounced detachment, large fissures, unclear cell layers, and pale staining. Statistical analysis using SPSS 27.0 software revealed significant differences in mean scores among the six fixatives (P<0.001). The fixation quality ranking was as follows: Davidson's fixative > 4% paraformaldehyde > Bouin's fixative > Carnoy fixative > Helly fixative > Zenker fixative. Zenker and Helly fixatives showed significantly lower scores than the other fixatives (P<0.001), while no significant differences were observed among the remaining fixatives (P>0.05). Conclusion Davidson's fixative provides the best fixation and staining results, followed by 4% paraformaldehyde and Bouin's fixative. Carnoy fixative exhibits suboptimal performance, while Zenker and Helly fixatives result in the poorest outcomes. Therefore, Davidson's fixative is recommended as the optimal fixative for golden hamster retinal tissue, with 4% paraformaldehyde, Bouin's and Carnoy fixatives as alternative options.

Institutions of higher education undertake a significant number of animal experiment projects with diverse types. To standardize animal experiments and ensure animal welfare, ethical review has become a core task for the Institutional Animal Care and Use Committee (IACUC) in these higher education institutions. A key issue worth exploring is how to improve the efficiency of animal ethical reviews while maintaining systematic quality of supervision. Based on the current status of ethical reviews at the Laboratory Animal Center of Huazhong University of Science and Technology, this paper designs and implements a full-process ethical review software system. This system seeks to offer solutions for the ethical review and supervision of animal welfare in institutions of higher education through information technology. The system employs a full-process supervision philosophy of "pre-approval, in-process supervision, post-review," focusing on strengthening the review and approval of animal research protocols, as well as post-approval monitoring. At the pre-approval stage, the system optimizes the process for designated members involved in the project review, ensuring that all projects comply with ethical standards and legal regulations. At the in-process stage, veterinary verification and consultation are carried out by executive veterinarians, using a method of "offline inspections and online records" for supervision. At the post-review stage, researchers are required to provide retrospective data to evaluate the experimental process. Additionally, this paper provides an in-depth exploration of the software, detailing its functional and non-functional requirements, as well as its security considerations. It also delves into the comprehensive software architecture, process design, and operational details. Furthermore, it illustrates the system's operational efficacy and impact since its launch. This paper discusses the software's applicability and practicality, analyzing existing limitations and challenges, such as the difficulty of balancing experiment urgency with the stringent nature of review processes, and the traceability blind spots in post-approval supervision. Future research will continue to enhance the accuracy and strength of animal welfare ethical reviews and supervision through new technologies and methods.

Objective To observe the spontaneous testicular tumors in interferon receptor-deficient mice (AG129) and provide a basis for further research using this mouse strain. Methods The AG129 mouse population was bred in an SPF barrier environment and reproduced normally. Among the 3-week-old weaned mice, we found that one male mouse had an abnormally enlarged testis, while none of the other mice in the same litter exhibited a similar condition. The spontaneous testicular tumor in this mouse was continuously monitored. The mouse was euthanized and dissected at 9 weeks of age. The gross morphology of the tumor was observed, and the tissue was then embedded in paraffin and sectioned for hematoxylin and eosin (HE) staining. Results After several weeks of observation, the tumor tissue gradually increased in size as the mice aged. Upon dissection, the tumor tissue was encapsulated in a smooth capsule. After opening the capsule, the tumor tissue was irregular in shape, with some areas being hard and others soft. The results of HE staining showed that the tumor tissue developed from tissues derived from multiple germ layers, with nerve tissue, bone tissue, muscle tissue, and adipose tissue inside, exhibiting an irregular morphological structure. Conclusion Based on the tumor development, gross morphological structure, and the HE staining results of the pathological sections, the tumor in this mouse was preliminarily diagnosed as an immature teratoma.

Objective To provide a reference for the diagnosis of amyloidosis in experimental animals through the pathological diagnosis of systemic amyloidosis in a case of a New Zealand white rabbit. Methods In a 6-month repeated ocular toxicity study, an abnormal finding was noted during the routine gross anatomical examination of one New Zealand white rabbit. Its organs were prepared as paraffin sections and stained with hematoxylin-eosin (HE) staining and Congo red staining. The histopathological features were observed under optical and polarized light microscopy. Results Gross anatomical examination of the animal revealed an enlarged spleen and changes in the color and texture of the lung. HE staining showed that the splenic tissue structure was destroyed, the white pulp of the spleen was surrounded by dense amyloid deposition in the form of nodular rings, along with pressure atrophy of the white pulp. Amyloid deposits were also observed in the submandibular lymph nodes, mesenteric lymph nodes, ileum, sacculus rotundus, vermiform appendix, jejunum, cecum, and rectum. Congo red staining showed that the amyloid deposition in the affected organs appeared salmon-pink, and exhibited characteristic apple green birefringence under polarized light microscopy.Conclusion The histo-pathological features of the New Zealand white rabbit are consistent with the diagnostic characteristics of systemic amyloidosis.