When applying embalmed cadavers and organ specimens to gross anatomy practice and surgical training, their qualitative properties serve as important functional indices of how closely they resemble the living state. Among these properties, color hue and stiffness change remarkably after fixation. In the present study, we evaluated the properties of rat organs, including the brain, lung, liver, and skeletal muscle, after fixation by immersion in a 10% formalin solution and a non-formalin fixative, ethylene glycol-methanol-phenol (EMP) mixture. The colorimetric L*a*b* values, which are indicators of the lightness and chromatic components, showed that, compared with formalin fixation, EMP fixation significantly increased lightness in the lungs and livers, suggesting decoloration as a result of hemolysis and hemochrome elution, whereas deposition of a reddish pigment was induced in the brains and skeletal muscles. The ΔE values, the total color difference from the unfixed state, were higher in the EMP- than in the formalin-fixed livers. The biomechanical parameters for stiffness indicated that the EMP-fixed brains were hardened similar to those fixed by formalin, while the other EMP-fixed organs were significantly hardened compared with their formalin-fixed counterparts. These findings suggest that EMP fixation exerts a beneficial effect by enhancing reddish coloration, especially in the skeletal muscles, and would be useful for reducing the total amount of highly toxic formalin used in gross anatomy practice.

Antimicrobial resistance is a global public health threat, and accurate antimicrobial susceptibility testing is crucial for guiding appropriate antimicrobial use. Although the disk diffusion method is widely used in livestock, standardized breakpoints for veterinary pathogens are lacking. Bovine respiratory disease, a major cause of economic loss in calves, is commonly associated with Pasteurella multocida and Mannheimia haemolytica. This study aimed to establish inhibition zone diameter cut-off values for disk diffusion and to create an antibiogram for these pathogens. The cut-off values were calculated based on minimum inhibitory concentration (MIC) reference values: the Clinical and Laboratory Standards Institute clinical breakpoints for penicillin and tetracycline; the European Committee on Antimicrobial Susceptibility Testing epidemiological cut-off values for kanamycin and tilmicosin (P. multocida); and MIC cut-off values calculated from this study for cefazolin, marbofloxacin, thiamphenicol, and tylosin. The cut-off values for penicillin and tetracycline provide useful guidance for clinical drug selection, whereas caution is required when interpreting the results for the other agents evaluated because their cut-off values were based on epidemiological cut-offs rather than clinical breakpoints. Re-evaluation of previously reported cut-off values for kanamycin, cefazolin, and tetracycline using a larger number of isolates provided more robust thresholds that were less susceptible to strain-specific variation. The antibiogram revealed low susceptibility rates for some agents. Because antimicrobial use is associated with the development of resistance, these findings indicate the need for prudent antimicrobial stewardship and continued surveillance of resistance in livestock pathogens.

Diet significantly influences the gut microbiota, with variations in macronutrient content (proteins, fats, and carbohydrates) and the presence of non-digestible carbohydrates, such as fiber, playing crucial roles in shaping microbial composition. This study investigated the effects of four commercial prescription diets (low-carbohydrate, weight-loss, high soluble fiber, and renal) on the fecal microbiome of five healthy domestic cats using a 4 × 4 Latin square design. Fecal samples were analyzed using Illumina sequencing of the bacterial 16S rRNA gene to assess bacterial community structure and diversity. Results showed that cats fed the renal diet (low protein, high carbohydrate, high fat) were associated with higher relative abundances of the class Actinobacteria, particularly Bifidobacterium. The low-carbohydrate diet was associated with higher relative abundances of Adlercreutzia, Collinsella, and Slackia. The high-soluble fiber diet was associated with a higher relative proportion of Streptococcaceae. In contrast, the renal diet was associated with lower relative abundances of Blautia and Erysipelotrichales. No significant differences were observed in alpha-diversity indices among diets, whereas beta-diversity analysis showed significant differences in microbial community composition among dietary groups. These findings suggest that dietary composition may influence the fecal microbiome in healthy cats. However, given the exploratory design and compositional nature of the sequencing data, these findings should be interpreted cautiously and considered hypothesis-generating.

Delayed postoperative hemorrhage (DEPOH) is recognized in sighthound breeds and has been associated with a SERPINF2 c.605C>T variant that affects alpha-2-antiplasmin, an important inhibitor of fibrinolysis. The distribution of this variant among dogs in Japan has not been investigated. To determine the frequency of the SERPINF2 c.605C>T variant in dogs presented to a single referral hospital in Japan. Genomic DNA was extracted from peripheral blood of dogs presented to the Animal Medical Center of Nihon University between July 2021 and October 2022. Genotyping of SERPINF2 c.605C>T variant was performed by real-time PCR using a TaqMan minor groove binder SNP genotyping assay. Adequate amplification was obtained in 433 of 436 samples. Homozygous variant genotypes (T/T) were detected in one Italian Greyhound, one Whippet, and two Shiba Inu dogs. Heterozygous genotypes (C/T) were detected in Saluki, Italian Greyhound, Shiba Inu, French Bulldog, mixed-breed dog, Boston Terrier, Jack Russell Terrier, and Chihuahua. Among non-sighthound breeds, Shiba Inu dogs had the highest observed variant allele frequency in this cohort (0.25). The DEPOH-associated SERPINF2 c.605C>T variant was detected in both sighthound and non-sighthound dogs in this Japanese referral-hospital cohort. The relatively high allele frequency observed in Shiba Inu dogs warrants further multicenter studies evaluating variant frequency and its relationship with clinical DEPOH.

Pelizaeus–Merzbacher-like disease type 1 (PMLD1), also known as hypomyelinating dystrophy 2, is a typical slowly progressive hypomyelinating leukodystrophy (HLD) that manifests in the neonatal period or early infancy. In humans, PMLD1 is inherited as an autosomal recessive trait, with genetic variants identified in the gap junction protein gamma 2 (GJC2) gene. Six juvenile-age Toy Poodle dogs exhibited coarse, vertical head and trunk tremors from immediately after birth. Conventional magnetic resonance imaging revealed uniform signal hyperintensities throughout the subcortical white matter in all dogs. All dogs were euthanized. Subsequent histopathological examination revealed vacuolar changes and demyelination in the cerebral and cerebellar white matter, leading to a diagnosis of HLD. Genetic analysis of five affected dogs identified a shared homozygous 14-base pair deletion in the GJC2 gene, XM_038556433.1:c.920_933del. To the best of our knowledge, this is the first report of a pathogenic GJC2 variant in dogs or any other domestic animal species. The results will enable genetic testing and provide a spontaneous large animal model for the homologous human disease.

Heart rate variability (HRV) analysis is widely used to evaluate autonomic nervous system activity. Although a fixed 16th-order autoregressive (AR) model is commonly used for human short-term frequency-domain HRV analysis, its applicability to dogs has not been validated. This study evaluated the suitability of the fixed 16th-order AR model for canine HRV analysis by comparing HRV indices obtained using AR(16) with those derived from Akaike’s Information Criterion (AIC)- and Bayesian Information Criterion (BIC)-selected AR models and the conventional fast Fourier transform (FFT) method. Twenty-three clinically healthy dogs underwent continuous heart rate monitoring for approximately 3 days using a wearable device. One stationary 5-min R-R interval segment was selected from each recording, and frequency-domain HRV indices were calculated using AR(16), AIC-selected AR models, BIC-selected AR models, and FFT. Agreement among methods was evaluated using intraclass correlation coefficients and Bland–Altman analysis. HRV indices obtained using AR(16) showed excellent agreement with AIC-selected model orders and good agreement with FFT, whereas agreement with BIC-selected model orders was lower, particularly for low-frequency-related indices. These findings support the applicability of the conventional fixed 16th-order AR model for canine frequency-domain HRV analysis and provide methodological validation for its use in future veterinary HRV research.

Cardiotoxicity of doxorubicin (DOX) and epirubicin (EPI) has not been thoroughly compared in dogs. Fractional shortening (FS) is considered insufficient for detecting early myocardial damage induced by these drugs. This study aimed to compare the cardiotoxicity between EPI and DOX and to investigate parameters associated with histopathological findings induced by these drugs. Eight healthy beagles were randomly divided into two groups and administered either DOX or EPI until development of anthracycline-induced cardiac dysfunction (AICD), defined as consecutive FS below 30%, or until reaching a cumulative dose of 300 mg/m². After the final evaluation, the dogs were euthanized, and cardiac tissues were histopathologically evaluated. One dog in the EPI group developed AICD after six administrations (cumulative dose of 168 mg/m²), whereas no other dogs did. The number of vacuolated myocardial cells was significantly higher in the DOX group than in the EPI group. In the DOX group, but not in the EPI group, longitudinal strain (A4C-LS) and tissue motion mitral annulus displacement (A4C-TMAD) from the left apical four-chamber view, global longitudinal strain, myocardial performance index and velocity-time integral from left ventricle, mitral annular plane systolic excursion, and high-sensitivity cardiac troponin I showed significant changes after treatment. Furthermore, A4C-LS and A4C-TMAD were correlated with the extent of myocardial collagen fibers. These results suggest that EPI induces less severe myocardial injury than DOX, although individual variability in drug sensitivity exists. Echocardiographic parameters such as A4C-LS and A4C-TMAD may serve as sensitive markers for early myocardial injury.

Nasopharyngeal stenosis (NPS) is a common upper airway disorder in cats, and balloon dilation (BD) is considered the least invasive treatment. However, advancing a BD catheter can be challenging in cases of severe or imperforate NPS. This technical note describes a simple access-establishing technique that enables BD in such cases. Six cats with NPS in which BD catheter passage was difficult underwent a modified procedure in which a 6-Fr tube was advanced transnasally and connected to an 8-Fr tube, enabling successful BD catheter placement in the nasopharynx. Dilation was confirmed via endoscopy, and all cases showed clinical improvement. No complications were directly attributable to the access technique. This method may facilitate BD in severe feline NPS.

Plasma D-dimer concentrations were measured in 15 cases with thromboembolism and 19 cases without thromboembolism among bovine patients with inflammatory diseases, and the clinical usefulness of plasma D-dimer as a thromboembolic marker was evaluated. No significant difference in plasma D-dimer concentrations was observed between the two groups. A receiver operating characteristic curve was created, and with a plasma D-dimer cutoff value of 0.38 mg/L, the sensitivity and the specificity were 86.7% and 31.2%, respectively. Furthermore, there was a large variability in plasma D-dimer concentrations in cases with thromboembolism. These results indicate that the measurement of plasma D-dimer alone in the diagnosis of thromboembolism in cattle does not have sufficient specificity. In a multivariate logistic regression analysis regarding thromboembolism detection, platelet count was significant in the likelihood ratio test, suggesting that considering platelet count in addition to plasma D-dimer may allow for the detection of thromboembolism.

A female cat (approximately 3 weeks of gestation) was referred for respiratory distress and pleural effusion. Echocardiography revealed dilation of the left atrium and left ventricle, and the cardiac index was markedly elevated (0.39 L/kg/min), raising suspicion for high-output heart failure (HOHF). The cat was treated with furosemide and enrofloxacin. Pleural effusion completely resolved in late pregnancy, and 45 days after delivery the cardiac index decreased to 0.22 L/kg/min. To our knowledge, this is the first report describing a transient HOHF associated with pregnancy in a cat, highlighting the clinical utility of echocardiographic cardiac index measurement for identifying this condition. Further accumulation of cases is needed to better characterise this condition in feline patients.

We investigated the health of Tokara horses (n=34) on Nakanoshima as part of conservation efforts for this breed. Although the horses were clinically healthy, elevated white blood cell count, neutrophil count and gamma-glutamyl transferase (GGT) levels were observed, leading to suspicion of chronic hepatic dysfunction and infectious disease. A survey revealed that the caretakers had been feeding the horses Leopard plant, which contains toxic pyrrolizidine alkaloids (PAs). The abnormal GGT levels observed in these horses may suggest the possibility of chronic PA poisoning resulting from the consumption of this plant. These findings suggest that raising awareness of poisonous plants and carefully managing plant species in grazing areas could enhance the conservation of native horse breeds.

As the frequency and significance of bone marrow (BM) infiltration in enzootic bovine leukosis (EBL) remain unclear, this study evaluated BM involvement and its relationship with peripheral blood (PB) findings in 11 cattle with EBL using PB evaluation, and BM aspiration cytology. BM infiltration was identified in 5 of 11 (45%) EBL cases based on BM smears. All EBL cases showed circulating atypical lymphocytes, although BM infiltration was not consistently present. Two cases with extreme PB lymphocytosis showed BM infiltration. Cytopenia was variably observed and was most severe in cases with extensive BM involvement. This study provides combined assessment of PB and BM changes in EBL cattle and suggests that such evaluation enables a more comprehensive characterization of hematological alterations.

Ectopic ossification is defined as bone formation at a site where no bone tissue typically exists and usually presents a trabecular bone structure. Rare cases of ectopic ossification in cardiac masses have been previously reported. In general, cardiac masses are diagnosed by echocardiography, computed tomography, and magnetic resonance imaging (MRI). MRI, in particular, has been used in studies to evaluate cardiometabolic function and tumors in various non-human primates (NHPs). Here, we report a 15-year-old male cynomolgus monkey with significant weight loss and arrhythmia observed during a routine checkup. This is the first report of a cynomolgus monkey in which a cardiac mass with bone metaplasia in the right ventricle was confirmed by echocardiography, radiography and MRI before death.

Capillariid nematodes, such as Aonchotheca putorii, Eucoleus aerophilus, E. boehmi, and Pearsonema plica, parasitize canids. Reports about these nematodes parasitizing red foxes (Vulpes vulpes) in Japan are limited, and there are no prior records of E. boehmi. This study investigated 56 red foxes captured in Hokkaido and detected eggs of the four above species and Calodium hepaticum in rectal feces, with E. boehmi showing the highest prevalence (48%) as the first report in Japan. Low-vacuum scanning electron microscopy revealed distinct egg surface textures that support the current microscopical species identification keys. This study reveals that capillariids are prevalent in foxes in Hokkaido and the high prevalence of E. boehmi suggests a potential infection risk to domestic dogs.

A 1-day-old Holstein calf presented with central corneal opacity and thickening, and a polypoid lesion in the medial canthus of the left eye, leading to vision loss and enucleation. Grossly, a mass extended from beneath the cornea to the medial intraocular region. Histologically, the mass was composed of proliferative foci of diverse mesenchymal elements, including mature cartilage and adipose tissue, immature cartilage and bone, and proliferating spindle-shaped cells in a myxoid stroma. Anterior segment abnormalities, including iris hypoplasia, iridocorneal adhesion, angle malformation, and lens anomalies, were also observed. The animal was diagnosed with an ocular choristoma with heterogeneous mesenchymal differentiation and anterior segment dysgenesis (ASD). To the best of our knowledge, this is the first report of choristoma with ASD in cattle.

A female Bornean orangutan (Pongo pygmaeus) raised in a zoo died at 60 years of age. The animal showed no clinical signs besides decreased gait speed. Pathological examination revealed small hemorrhagic foci in the cerebral cortex and liver fibrosis with fatty degeneration of the hepatocytes. To evaluate aging lesions, the brain was examined histologically and immunohistochemically. Severe amyloid β (Aβ) deposition was observed in the cerebral cortex and vascular walls. Parenchymal Aβ deposits in the cerebral cortex appeared as diffuse plaques. Loss of smooth muscle was observed in the vascular walls affected by Aβ deposition. In contrast, only a few phosphorylated tau aggregates were observed. This report describes severe Aβ deposition in the brain of the oldest orangutan ever reported, which did not exhibit significant tau pathologies.

Three Japanese Black calves died within a two-month period on a beef cattle farm. Necropsy consistently revealed liquefactive necrosis of the ventral brain (extending from the olfactory bulb to the midbrain) and thymic atrophy. Histopathologically, necrosuppurative encephalitis characterized by abundant fungal hyphae was observed in all three cases. Fungal lesions also involved the olfactory mucosa, olfactory nerves, and olfactory bulb. Fungi isolated from the cerebrum of all three calves were identified as Lichtheimia ramosa. These cases were diagnosed as rhinocerebral mucormycosis, originating in the olfactory mucosa and extending to the cerebrum. Although mucormycosis is typically sporadic, this report documents the first occurrence of consecutive cases of bovine rhinocerebral mucormycosis caused by L. ramosa.

An 11-year-old toy poodle presented with abnormal gait. Magnetic resonance imaging revealed a demarcated intradural extramedullary mass at the dorsal medulla oblongata, which was surgically removed. Histopathologically, a well-demarcated tumor was composed of small nests of meningothelial neoplastic cells separated by abundant fibrovascular tissue. The nuclei of neoplastic cells were often eccentric due to eosinophilic cytoplasmic inclusion bodies. Immunohistochemically, the neoplastic cells were positive for E-cadherin and vimentin, and endothelial cells were positive for CD31, von Willebrand factor, and vimentin. The cytoplasmic inclusion bodies of the neoplastic cells were E-cadherin-positive and, by electron microscopy, composed of folded membrane-like structures. The tumor was diagnosed as an angiomatous meningioma with cytoplasmic inclusion bodies, which were likely cell membranes containing E-cadherin.

Pulsed electromagnetic field (PEMF) therapy, a commonly used supplementary treatment in the horse industry, shows promise in enhancing circulation, reducing inflammation, and supporting cellular repair; however, its effects on equine physiology remain unclear. Limited research and inconsistent protocols create uncertainty about its efficacy and safety in horses. Our study evaluates the short-term effects of PEMF on hematological and biochemical parameters in horses. Five active sport horses underwent PEMF therapy for five consecutive days using a full-body blanket at specific frequencies. Blood samples were collected both before and after treatment to assess 72 hematological, biochemical, and endocrine parameters. Pre- and post-treatment data for each parameter were analyzed and compared. While most hematological parameters remained stable, significant alterations were observed in reticulocyte and platelet counts, as well as hemoglobin levels. Blood biochemistry exhibited greater variability, with notable changes in plasma proteins, bilirubin, uric acid, creatine kinase, creatinine, liver enzymes, and iron-binding capacity. No significant changes were observed in cortisol or thyroxine levels. According to our exploratory data, whole-body PEMF therapy showed no detectable adverse effects over five days on health or stress response. While most parameters remained unchanged, significant biochemical and hematological changes suggest that PEMF may support the animals and warrant further research on its mechanisms and applications.

This study evaluated the efficacy and safety of a sedation protocol through the nares combining dexmedetomidine with midazolam and butorphanol in cockatiels. Six adults were enrolled in a randomized, 4 treatment, 4 period crossover trial comparing a control regimen (midazolam 3 mg/kg and butorphanol 3 mg/kg) with three combinations including dexmedetomidine at 0.04, 0.06, or 0.08 mg/kg, administered through the nares. The volume of all treatments was standardized to the volume of the highest dose of dexmedetomidine administered (2 mL/kg) with sterile saline solution. Sedation scores, respiratory rate, heart rate, and cloacal temperature were recorded for 10 min after drug administration and during 15 min of manual restraint, followed by flumazenil and atipamezole via the nares for reversal. All birds completed all treatments; mild sneezing occurred but no clinically relevant respiratory complications were observed. Medium and high dose dexmedetomidine produced higher sedation scores and lower respiratory rate, heart rate, and body temperature during restraint than the control regimen, whereas the control group showed increased respiratory rate, suggesting insufficient suppression of restraint induced stress. In all groups, sedation and physiological variables returned to near baseline values within 15 min after reversal, and no serious adverse events occurred. These findings indicate that administration through the nares dexmedetomidine at 0.06 or 0.08 mg/kg combined with midazolam and butorphanol provides deeper, more stable, and reversible sedation and improved control of stress responses in cockatiels and may represent a clinically useful protocol in this species.

Gallbladder mucocele is frequently associated with concurrent hepatic pathology. However, studies examining the clinical relevance of concurrent liver histopathological findings in this condition remain scarce. This retrospective study evaluated liver histopathological findings in dogs that underwent cholecystectomy with concurrent liver biopsy and investigated their associations with preoperative variables, postoperative alanine aminotransferase (ALT) kinetics, and overall survival. Vacuolar degeneration was the most common histopathological finding, followed by hepatic fibrosis and neutrophilic cholangiohepatitis. The severity of neutrophilic cholangiohepatitis was positively correlated with preoperative serum bilirubin concentrations and common bile duct diameter and was associated with reduced postoperative survival. Conversely, the severity of fibrosis was primarily associated with the duration of postoperative ALT elevation. These findings suggest that concurrent liver histopathology, particularly the severity of neutrophilic cholangiohepatitis, may provide clinically relevant information regarding preoperative cholestatic changes and postoperative outcomes in dogs that underwent cholecystectomy for gallbladder mucocele.

Photodynamic antimicrobial chemotherapy (PACT) for infectious keratitis has attracted increasing attention, and the clinical application of PACT with TONS504, a newly developed chlorin derivative, is anticipated. However, studies evaluating the cytotoxicity of TONS504 combined with light exposure on corneal cells are lacking. We aimed to investigate cytotoxic effects on the corneal epithelium and examined safe irradiation conditions by evaluating the cytotoxicity of TONS504, blue light (405 nm), and their combination using porcine corneal epithelium (PCEP). Additionally, the synergistic cytotoxicity of TONS504 with ethylenediaminetetraacetic acid (EDTA) under blue light—previously shown to have a synergistic antimicrobial effect with PACT—was assessed. Viability of PCEP cells exposed to various TONS504 concentrations (1–100 mg/L), irradiation intensities (5–30 J/cm², 20 mW/cm², 405 nm LED), and their combinations were evaluated using the Cell Counting Kit-8 assay. Inhibition of PCEP cell migration under these conditions was assessed using a primary porcine corneal explant model. The synergistic cytotoxicity of TONS504 with EDTA (0.015 M) under blue light irradiation at 5 J/cm² was also evaluated similarly. TONS504 alone demonstrated low cytotoxicity (up to 10 mg/L), whereas the combination of TONS504 with blue light showed concentration-dependent cytotoxicity or cytotoxicity at high light irradiation intensity against PCEP cells. No clear synergistic cytotoxicity was observed between TONS504 and EDTA under blue light. These findings provide fundamental data for establishing a blue light-based TONS504-PACT protocol.

A 5-year-old cat presented with exophthalmos and neurological signs. Aspergillus udagawae was identified by histopathological examination and polymerase chain reaction (PCR) analysis of an orbital mass. Although magnetic resonance imaging suggested intracranial infection, cerebrospinal fluid (CSF) analysis and fungal culture were not clear. Serial CSF PCR detected Aspergillus sp., leading to diagnosis of central nervous system (CNS) infection and monitoring of treatment response. Following surgical debulking and administration of antifungal agents including voriconazole, the clinical signs resolved and CSF PCR reverted to negative. This case suggests that CSF PCR is a sensitive adjunctive tool for diagnosing and monitoring CNS aspergillosis in cats when conventional methods are inconclusive.

Snakebite-induced local tissue damage remains a challenge in snakebite envenoming management because venom toxins rapidly disrupt vascular and extracellular matrix integrity at the bite site. This study evaluated the inhibitory effect of marimastat, an inhibitor of zinc-dependent metalloproteinases, against local tissue damage induced by Indonesian Trimeresurus insularis and Calloselasma rhodostoma venoms in a mouse skin model. The minimum hemorrhagic dose (MHD) of C. rhodostoma venom was determined in BALB/c mice and estimated to be 7.07 µg, while the MHD of T. insularis was adopted from a previous study. Mice received intradermal injections of venom at 2× MHD, either alone or pre-incubated with marimastat at venom:marimastat ratios of 1:1, 1:5, and 1:10 based on MHD equivalents. Macroscopic hemorrhage and histopathological changes, including erythrocyte extravasation, inflammatory cell infiltration, and collagen degradation, were assessed three hours after injection. Both venoms induced marked hemorrhagic lesions and tissue damage. Marimastat reduced venom-induced hemorrhage in both models, with near-complete inhibition in the T. insularis 1:10 group and complete inhibition in the C. rhodostoma 1:10 group. Marimastat also decreased erythrocyte extravasation, inflammatory infiltration, and collagen degradation, indicating preservation of microvascular and dermal matrix integrity. These findings support the central role of snake venom metalloproteinases in local viperid tissue damage and highlight marimastat as a promising adjunctive treatment for reducing venom-induced skin injury.