The pathogenicity of avian influenza virus (AIV) is governed primarily by the hemagglutinin (HA) glycoprotein. Highly pathogenic avian influenza viruses contain a highly cleavable HA molecule susceptible to ubiquitous host proteases, such as furin, resulting in severe systemic infections. In contrast, low-pathogenic avian influenza viruses have HAs that require activation by trypsin-like proteases, restricted to specific organs, causing localized and mild infections. We generated highly pathogenic virus variants by serially passaging low-pathogenic waterfowl isolates that originally replicated poorly in domestic poultry. The increased pathogenicity was correlated with a shift from a low-pathogenic to a highly pathogenic motif in the HA cleavage site. These findings suggest that benign viruses maintained in wild waterfowl in nature have the potential to become highly pathogenic variants during circulation and adaptation in chickens. Moreover, the host specificity of AIV is also primarily determined by the HA glycoprotein. AIVs usually replicate less efficiently in humans, whereas human influenza viruses replicate poorly in birds. This host restriction largely reflects differences in receptor-binding specificity of the HA protein. Most AIVs preferentially bind to sialic acid receptors with α2,3-linked galactose (SAα2,3Gal), while human viruses prefer the SAα2,6Gal linkage. Interestingly, both receptor types are expressed in the respiratory epithelium of pigs. Swine serve as “mixing vessels” that facilitate the reassortment of viruses between avian and human strains. These results provide a molecular basis for the key mechanisms underlying the emergence of novel influenza viruses with pandemic potential in humans.

Information on inflammatory laryngeal masses in dogs remains extremely limited. We aimed to describe the clinical and histopathological features and outcomes of five dogs with bilateral, movable inflammatory laryngeal masses. Stridor was a common clinical sign, followed by dysphonia and snoring, all of which were mild. The presence of movable masses was confirmed in all dogs through fluoroscopic or echolaryngographic evaluation. Laryngeal endoscopy identified two masses in each dog, consistent with everted laryngeal saccules. Surgical excision was performed in all dogs, and no recurrence was observed during a median follow-up of 13 months. Histopathological analysis revealed chronic laryngitis characterized by fibrosis, lymphoplasmacytic infiltration, edema, and lymphangiectasia, consistent with findings reported in laryngeal saccules associated with brachycephalic airway syndrome in dogs.

Multiple cats in an overcrowded colony died of acute kidney injury with renal amyloidosis. To investigate the etiology of these deaths, we performed histological analysis of the kidneys of 27 colony cats and 29 noncolony cats (8 with acute kidney injury, 9 with chronic kidney disease, and 12 nonazotemic). Congo red-positive amyloid deposition was observed prominently in the glomeruli and cortical and medullary interstitium and was identified as AA amyloid using permanence. The prevalence and severity of renal amyloidosis were significantly higher in colony cats than in noncolony cats. Feline immunodeficiency virus showed no association with feline leukemia virus infection. Based on our results, adverse environmental conditions may accelerate the incidence of feline renal amyloidosis.

The classical late-infantile form of neuronal ceroid lipofuscinosis type 2 (CLN2 disease) is a fatal lysosomal disorder characterized by progressive motor decline and premature death. A CLN2 cynomolgus macaque (Macaca fascicularis) model closely replicates the late-stage clinical and pathological features of human CLN2. To evaluate motor deterioration in this model, we conducted two behavioral assessments—the CLN2 Macaque Clinical Rating Scale and the Apple test—from the pre-onset stage in one macaque. Hypokinesia was observed as the first symptom at 22 months of age, followed by a marked decline in forelimb movement from 27 months. These simple, non-invasive, and cost-effective tests are valuable tools for monitoring disease progression and may facilitate the future clinical evaluation of therapeutic strategies for CLN2.

Vitellogenin (Vtg) and its receptor (VtgR)—essential for yolk deposition and transovarial pathogen transmission in ticks—are compelling targets for antibody-based intervention. To investigate their interaction in the tick Haemaphysalis longicornis, we employed AlphaFold2 to model the β-barrel domain of the midgut-synthesized paralog HlVtg1 and the first three ligand-binding repeats (LBR1–3) of HlVtgR. Subsequent protein–protein docking in Molecular Operating Environment (MOE) revealed a recurrent binding interface centered on HlVtg1’s Glu87, which formed persistent electrostatic interactions with LBR1–3 across top-ranking poses. Our results support a “monomeric engagement” model, where a single HlVtg1 monomer simultaneously engages all three low-density lipoprotein receptor class-A (LDLRA) domains of HlVtgR. This mechanism contrasts with the classical dimeric model and challenges prior inferences about stoichiometry and symmetry of binding sites. The predicted contact residues defined here may serve as a useful basis for evaluating candidate epitopes for interventions aimed at disrupting oocyte maturation and transovarial transmission of pathogens in H. longicornis.

Cutaneous inverted papilloma is rarely reported in avian species. In this study, an oriental turtle dove presented with subcutaneous masses in the neck, thorax, and leg. Histopathological examination revealed an inverted proliferation of basaloid squamous epithelial cells in a cord-like, lobulated growth pattern containing Civatte/colloid body-like structures, which extend into the abundant stroma with melanosis. Proteomic analysis of formalin-fixed paraffin-embedded tissues identified Keratins 14- and 5-like proteins, with lower levels of Keratins 6A-, and 4-like proteins. Immunohistochemistry confirmed strong reactivity of Keratin 14 in the basal layers of the tumor. This case of cutaneous inverted papilloma was distinguished by unique Civatte/colloid body-like structures and the accumulation of several keratins.

This study investigated the effects of soy isoflavone yeast fermented extract (soyF) and soy isoflavone yeast unfermented extract (soyN) on rat ileal smooth muscle contraction. SoyF and soyN inhibited carbachol (CCh)- or KCl-induced contraction in a concentration-dependent manner; however, these effects were stronger for CCh-induced contraction than that for KCl, and the relaxation effect was stronger for soyF than for soyN. SoyF-induced relaxation was attenuated by 4-aminopyridine (4-AP), a Kv channel inhibitor, and iberiotoxin (IbTX), a calcium-activated potassium channel (BK channel) inhibitor. This relaxation was also decreased by 9-(tetrahydrofuran-2-yl)-9h-purin-6-amine (SQ22536) and 1H-[1, 2, 4]oxadiazolo[4,3-a] quinoxalin-1-one (ODQ). Moreover, simultaneous treatment involving SQ22536 with 4-AP or IbTX further restored soyF-induced inhibition compared with each single treatment, whereas simultaneous treatment with ODQ and 4-AP or IbTX did not restore soyF-induced inhibition. SoyF increased cyclic adenosine monophosphate (cAMP) and cyclic guanosine monophosphate (cGMP) levels in ileal strips. In β-escin-permeabilized muscle, CCh, guanosine 5’-O(3-thiotriphosphate) (GTPγS), and phorbol-12,13-dibutyrate (PDBu)-enhanced Ca²⁺-induced contraction, but soyF suppressed this Ca²⁺ sensitization. In summary, yeast-fermented treatment increased soy isoflavone-induced inhibition of ileal smooth muscle contraction. These data suggest that soyF-induced relaxation was due to increasing cAMP and cGMP related to activating adenylate cyclase and guanylate cyclase. Moreover, it was demonstrated that soyF-induced relaxation is due to cell membrane hyperpolarization and inhibition of contractile proteins. Cell membrane hyperpolarization is probably mediated by the activation of Kv and BK channels via cGMP-related signals. Furthermore, the inhibitory effect on the contractile protein is due to Ca²⁺ desensitization, probably through suppression of the Rho kinase/myosin phosphatase targeting subunit (MYPT) and/or the PKC/CPI-17 pathway.

Cholesterol gallstones (CGs) are formed in the biliary system due to cholesterol supersaturation in the bile and delayed bile excretion. The current treatments for CGs involve potentially severe complications, and novel therapeutic approaches are still required. Shigyakusan is a traditional Chinese medicine used for treating CG disease (CGD), but there are no reports on the action or efficacy of Shigyakusan in CGD. The present study was conducted to clarify the inhibitive effects of Shigyakusan on CGD. Mice were fed a normal or lithogenic diet for 8 weeks (to create a mouse model of CGD) and simultaneously treated with vehicle or Shigyakusan. Organs were removed after blood sampling to examine CG formation and perform pathological evaluations. Genetic analysis of the liver, gallbladder, and ileum tissues was also conducted. CGD was induced by feeding mice with a lithogenic diet. Specifically, gallstones were detected, and serum T-CHO and LDL-C were significantly elevated. Administration of Shigyakusan to CGD mice reduced the development of CGs and lowered the serum T-CHO and LDL-C levels. Additionally, Shigyakusan administration increased ABCG5/G8 and ABCB4 mRNA expression in the liver, AQP5 expression in the gallbladder, and ABCG5 expression in the ileum of CGD mice. Shigyakusan administration diminished the synthesis of CGs in mice by lowering serum cholesterol and improving bile flow. The results show that Shigyakusan may be a beneficial option for CGD treatment and prevention.

Antimicrobial resistance in Escherichia coli is a growing concern in both human and veterinary medicine. Although fluoroquinolone-resistant (FQ-R) E. coli has been reported in companion animals, no integrated analysis incorporating antimicrobial susceptibility, clonality, resistance genes, and virulence factors (VFs) to assess human health risks has been conducted in Japan. This study aimed to characterize FQ-R E. coli isolates from companion animals in Sapporo, Japan by identifying antimicrobial susceptibility, clonality, resistance genes, and VFs. Among 106 animals sampled, 33.0% carried FQ-R E. coli. Among 104 FQ-R E. coli isolates, 58 isolates (55.8%) were identified as ST131. Whole-genome sequencing of 35 representative FQ-R E. coli isolates, including 20 ST131 isolates, showed that the ST131 isolates were distributed among five clades/sub-clades (C1-nM27, C1-M27, A, C2 and Unclassified), indicating increased clade diversity compared to previous years. ST1193, another international high-risk clone, was also detected. All isolates harbored mutations of quinolone resistance-determining regions in gyrA and parC, and 51.4% carried bla_CTX-M genes, including bla_CTX-M-27 and bla_CTX-M-14. Most isolates remained susceptible to aminoglycosides and cefmetazole, although the latter is not approved for veterinary use in Japan. Additionally, 72 VFs were identified, and eight were shared by all isolates, suggesting potential risk to human health. Our findings indicate that companion animals share certain E. coli lineages including ST131 and ST1193 with humans. Prudent antimicrobial use and routine hygiene practices are essential to limit the transmission. Further studies incorporating human and environmental isolates are needed to better understand the transmission dynamics of FQ-R E. coli within communities.

Antimicrobial-resistant bacteria in wild animals are a multisectoral concern worldwide. In this study, we examined fecal samples collected from wild birds in two prefectures of Japan between 2021 and 2024 using both deoxycholate-hydrogen sulfide-lactose (DHL) agar media and antimicrobial-containing DHL agar media. Of the 252 fecal samples from 11 bird species, 159 E. coli were isolated from 70 samples (27.8%) of six species, and resistance was found in 4.4% of isolates from DHL media. Using nalidixic acid (NAL)- and cefotaxime (CTX)-containing media, NAL-resistant isolates were isolated from great cormorants and spot-billed ducks, and an extended-spectrum β-lactamase (ESBL)/AmpC β-lactamase producer was isolated from great cormorants. Next-generation sequencing analysis of 19 E. coli isolates exhibiting resistance to NAL and/or CTX indicated diverse genotypes. Genetic analysis indicated that amino acid substitution of quinolone-resistance-determining-regions and qnrS were responsible for NAL resistance, and CTX-Ms (bla_CTX-M-14 in three isolates, and bla_CTX-M-15 and bla_CTX-M-55 in each) and AmpC β-lactamase (bla_MOX-4 and bla_CMY-2 in each) were responsible for CTX resistance. Despite the presence of certain resistant strains, the overall prevalence of antimicrobial-resistant E. coli remains low in wild birds, suggesting limited environmental exposure to antimicrobials and antimicrobial resistant bacteria.

Oxidative stress has attracted attention as an indicator of exercise load. Minimizing the impact on the body is essential during underwater treadmill exercise. Here, we conducted an exploratory study of the effects of dermal suction, which has been reported to improve blood flow in healthy dogs, prior to underwater treadmill exercise. Five healthy beagles (two neutered males and three spayed females) underwent dermal suctioning with Medicell for PETS over the entire body for 30 min. Underwater treadmill exercise was performed (water temperature: 32–33°C, water level: hip joint, load: 1.5 km/hr for 20 min). Blood samples were collected immediately before; immediately after; and 1 hr, 1 day, and 3 days after the underwater treadmill exercise; the diacron-reactive oxygen metabolites (d-ROMs), indicating the oxidation level, and biological antioxidant potential (BAP), indicating antioxidant capacity, were measured to determine the BAP/d-ROMs ratio as the potential antioxidant capacity. The results showed that dermal suction significantly decreased d-ROMs 3 days after underwater treadmill exercise, and the BAP/d-ROMs ratio was significantly higher immediately after exercise and 1 and 3 days after dermal suctioning. The parasympathetic nervous system is activated by dermal suctioning, resulting in muscle relaxation and mild psychological change. This study showed that dermal suction tended to decrease oxidative stress after exercise. Future studies should consider effects on the nervous system and exercise intensity indices and should be conducted in larger canine cohorts.

Feline colorectal adenocarcinoma is a malignant tumor with a poor prognosis due to its locally invasive and metastatic nature. Surgical resection remains the mainstay of treatment, but accessing distal colorectal lesions is often challenging due to pelvic anatomy. This study aimed to evaluate the feasibility, postoperative outcomes, and prognosis associated with Swenson’s pull-through procedure in feline patients with distal colorectal adenocarcinoma. Six cats with colorectal adenocarcinoma underwent tumor resection using Swenson’s pull-through technique were included. Clinical records were retrospectively reviewed to assess perioperative complications, completeness of resection, disease-free survival (DFS), and overall survival (OS). All tumors, with a resection margin of 2 cm, were involved the pelvic cavity, and the median tumor size was 2.0 cm. In all cases, the horizontal resection margins were histologically clear, and metastasis was histologically confirmed in the left colonic lymph nodes. Five cats experienced diarrhea as a short-term postoperative complication during hospitalization, which resolved within approximately 1 month. One cat developed colonic stenosis that was managed with balloon dilation. The median DFS and OS were 150 and 225 days, respectively. These findings suggest that Swenson’s pull-through is a feasible and effective surgical option for achieving local tumor control and symptom improvement in cats with distal colorectal adenocarcinoma.

This study aimed to determine the optimal stifle joint angle for the lateral fabellotibial suture (LFTS) technique in small dogs with cranial cruciate ligament rupture (CCLR), by quantitatively assessing biomechanical parameters using pressure mapping and a 3D-printed tension assistant device. LFTS procedures were performed on 12 canine hindlimb cadaveric models divided into five groups: (1) Intact group, (2) cranial cruciate ligament-deficient (CCL) group, and (3–5) stifles fixed at 90°, 105°, and 135° (L90, L105, L135). Suture tension was quantitatively measured using a tensioner. Postoperative evaluations included pedobarography, tibial rotation angle, patellofemoral contact pressure, and femorotibial contact pressure, analyzed via force-sensitive resistors and pressure-sensitive films. Pressure mapping visualizations were used to evaluate joint mechanics and pressure distribution. Statistical analyzes were conducted using two-way ANOVA with post-hoc testing. The applied suture tension differed significantly among angle-fixed groups (P<0.05). Significant correlations were observed between experimental groups and pad pressure distribution (P<0.001). No significant difference in femorotibial contact pressure was noted between the L105 and intact groups. These results suggest that a stifle angle of 105° during LFTS most closely replicates normal joint contact mechanics, offering practical insights for optimizing tensioning protocols in small dogs.

This study hypothesized that heat and cold stress affect the balance between oxidants and antioxidants (oxidative stress) of oocytes and follicular fluid (FF) in beef cattle and the oxidative stress between blood and FF is correlated. Thirty-two Japanese Black cattle that were divided into four seasonal groups [fall, winter (WG), spring (SpG), and summer (SmG) group]. Plasma and FF were measured diacron-reactive oxygen metabolites (d-ROMs), biological antioxidant potential (BAP), and oxidative stress index (OSI). Reactive oxygen species (ROS) were measured in oocytes. Temperature-humidity index was lower in WG and higher in SmG than in the other three groups (P<0.05). d-ROMs value was lower in FF than in plasma in all groups, BAP value was lower in FF than in plasma in WG, SpG, and SmG, and OSI was lower in FF than in plasma in WG and SpG (P<0.05). In FF, d-ROMs and BAP values were positively correlated in WG, SpG, and heifer groups (HG, P<0.05). d-ROMs or OSI values between plasma and FF were positively correlated in all animals and cow group (CG), SpG, CG, and HG (P<0.05). ROS levels in oocytes were higher in WG and SpG than in SmG (P<0.05). In conclusion, oxidative stress in the blood and FF are linked, and oxidative stress of oocytes increases in winter and spring in beef cattle that are kept on pasture, except in winter.

Local anesthetics such as lidocaine have been used in humans and other animals to perform surgical procedures, therapeutics, and experiments. Lidocaine discarded into the environment through industrial waste, human and animal excretion, and household waste has been detected in the aquatic environment. For example, lidocaine in rivers, lakes, and influent and effluent water has been detected at wastewater treatment plants (7 ng/L–2.06 μg/L), suggesting that this chemical substance influences aquatic animals. However, the toxic effects of lidocaine on marine organisms have not been investigated. This study examined the acute toxicity of local anesthetics (lidocaine and dibucaine) on the marine zoea larvae of red-clawed crabs, which feature a life cycle in which adults live on land and larvae live in the sea. Survival analysis of zoea larvae revealed that dibucaine was more toxic than lidocaine. The 50% effective concentrations (EC₅₀s) for lidocaine and dibucaine were 1.64 × 10⁻³ and 4.63 × 10⁻⁵ M, respectively, after 24 hr of exposure. Next, RNA sequencing was performed using the EC₅₀ of each drug. Both local anesthetics were highly toxic to the kidneys, in addition to their effects on the heart, nerves, and liver. These local anesthetics were also found to affect melatonin metabolism and possibly decrease melatonin levels in zoea larvae. To the best of our knowledge, no prior study conducted a comprehensive analysis of the effects of local anesthetics on aquatic larvae, illustrating the need to focus on the toxicity of these drugs in aquatic animals.

Parrot bornavirus (PaBV), the etiological agent of proventricular dilatation disease (PDD), poses a significant threat to captive psittacine birds worldwide. This study investigated the prevalence, genotype distribution, and phylogenetic characteristics of PaBV in captive psittacine birds in Thailand. A total of 231 birds from three families (Psittaculidae, Psittacidae, and Cacatuidae) were sampled across five regions in Thailand. Nested PCR targeting the nucleoprotein gene detected PaBV in 13.85% (n=38) of samples, with 81.58% of positive cases being asymptomatic, suggesting a potential carrier state. Choanal swabs were the most effective for detecting PaBV, although some positive cases were identified exclusively in other specimen types, indicating the importance of using multiple sample types for accurate diagnosis. Genotyping revealed the presence of two viral variants: PaBV-2 and the more prevalent PaBV-4, with the latter being predominant and further classified into two distinct groups. The continued presence of PaBV in captive birds raises concern over possible spillover into native wild psittacine populations, several of which are classified as “Near Threatened” by the IUCN. These findings underscore the importance of regular monitoring and molecular surveillance in both captive and wild bird populations to inform effective disease management and conservation strategies.

African swine fever virus (ASFV) genome encodes over 170 genes, but only a small number have been investigated for their roles in disease progression. Understanding the genetic and biological functions of these lesser-known genes accelerates the specification of open reading frames involved in pathogenesis in host animals and the development of ASF vaccines. In this study, we deleted the I196L gene of the highly virulent parental strain AQS-C-1-22 to generate the ASFV mutant AQSΔI196L. In vitro, AQSΔI196L replicated similarly to the parental virus in immortalized porcine kidney macrophage cultures. Pigs intramuscularly inoculated with 10² median tissue culture infectious dose (TCID₅₀) AQSΔI196L developed similar clinical signs and consequences (e.g., high fever, anorexia, and death) as infections with the parental strain. However, viremia in AQSΔI196L-inoculated pigs was slightly reduced compared with pigs inoculated with the parental strain. These findings suggest that the I196L gene does not significantly affect the pathogenicity of the virus in pigs.

In November 2024, the animal health authority of Japan reported the nation’s first case of lumpy skin disease (LSD) at a dairy farm in Fukuoka, Kyushu. Although a total of 22 farms were affected—17 dairy, 3 beef, and 2 mixed—the epidemic was effectively contained within two months through strict control measures. PCR testing confirmed the presence of LSD virus in skin nodules from suspected cattle at the index farms, and infectious virus was isolated. Phylogenetic analysis based on the complete genome sequence indicated that the virus detected in Japan was closely related to strains that have recently circulated in East and Southeast Asia.

The status of co-infection with porcine reproductive and respiratory syndrome virus type 1 (PRRSV-1) and type 2 (PRRSV-2) in Japan is poorly understood. A case of such co-infection was identified on a PRRSV-1 non-vaccinated farm in Kagoshima prefecture. Both PRRSV-1 and PRRSV-2 genomes were simultaneously detected in pig samples by RT-PCR, and molecular analysis confirmed PRRSV-1/PRRSV-2 co-infection in individual piglets. The PRRSV-1 strain (020-P4-EU) was classified as lineage 1 (sublineage: L1.2), showing high similarity to the Unistrain^® PRRS vaccine and a Korean strain. The PRRSV-2 strain belonged to lineage 4 (Cluster III). These findings provide molecular evidence of PRRSV-1/PRRSV-2 co-circulation in Japan, suggesting the complex epidemiology of PRRSV in this region.

Porcine parvovirus (PPV) is a major cause of reproductive failure in pigs. This study reports the first detection of a PPV 27a-like strain in Japan. A total of 387 samples from 113 cases (2015–2024) were analyzed, revealing 35 PPV-positive cases. Phylogenetic analysis identified the NG2794-2-3/2019 strain as a 27a-like variant. Experimental infection in pregnant sows resulted in fetal death and mummification, confirming pathogenicity. The strain exhibited prolonged viremia, indicating a high transmission risk. Owing to antigenic differences from vaccine strains, conventional PPV vaccines may be ineffective. This study highlights the urgent need for enhanced vaccines to control PPV-related reproductive disorders in Japan.

This study reports the first documented case of neoplasia in a wild Amami rabbit, an endangered species endemic to the Amami-Oshima and Tokunoshima Islands in Japan. In January 2018, a deceased Amami rabbit was found on a rural road on Tokunoshima Island. Necropsy revealed hemorrhage, cervical vertebral dislocation, generalized lymphadenopathy, a 5 × 5 cm mediastinal mass encasing the heart, and splenomegaly. The rabbit’s death was presumed to be due to vehicle collisions following emaciation from systemic tumor progression. Histopathological examination showed significant proliferation of tumor cells like lymphocytes. Polymerase chain reaction analysis of the tumor did not detect retroviral or herpesviral sequences. This case highlights the importance of ongoing pathological surveillance and conservation efforts for this endangered species.

Leptospirosis, a global zoonosis caused by Leptospira spirochetes, has been isolated from various wild mammals. This study evaluated clinical and pathological changes in an adult male Amami rabbit (Pentalagus furnessi) infected with Leptospira interrogans. In the present study, interstitial nephritis and Leptospira antigen were observed in the kidney of an Amami rabbit. There were no lesions associated with Leptospira infection in other organs examined. Further study is needed to determine the pathogenic effect of Leptospira infection in this animal species.