The use of fully threaded headless cannulated screws for femoral neck fracture fixation in small-breed dogs show promise in cadaveric study.

OBJECTIVE: To biomechanically evaluate the stability of internal fixation methods for femoral neck fractures in small-breed dogs. Furthermore, the possibility of replacing the headed screw with fully threaded headless cannulated screws in the fixation method was assessed. METHODS: The study was conducted from December 12, 2023, to February 7, 2024. A total of 18 femurs from 9 canine cadavers were used in this study. After a simple neck fracture was created, in group A (n = 6), the fracture was stabilized with three 1.1-mm parallel Kirschner wires (K-wires). In group B (n = 6), a 3.0-mm partially threaded cannulated screw and an antirotation pin were used. In group C (n = 6), a 2.5-mm fully threaded headless cannulated screw and an antirotation pin were used. A mechanical test was conducted to apply a single axial compressive load to the femoral head. RESULTS: 9 adult small-breed dogs weighing 3.6 to 8.3 kg (mean ± SD; 5.9 ± 1.6). The mean maximum failure load was highest in group C (495 ± 81 N), followed by group B (454 ± 50.4 N), and then group A (222 ± 21.6 N). Significant differences in maximum failure load were observed between groups A and B as well as groups A and C but not between groups B and C. CONCLUSION: The use of fully threaded headless cannulated screws presents a promising method for internal fixation of canine femoral neck fractures. CLINICAL RELEVANCE: To demonstrate the potential stability and reliability of fully threaded headless cannulated screws.

Biomechanical evaluation of three fixation methods in a feline transverse patella fracture model.

OBJECTIVES: This study aimed to compare the biomechanical properties of three stabilisation techniques in feline patella transverse fractures and select the strongest method with potentially minimal complications. METHODS: Patella fracture was simulated in 27 feline cadaveric pelvic limbs (mean weight of the cadavers 3.78 kg), and the limbs were randomly grouped to be stabilised with one of the three stabilisation methods. The modified tension band wiring technique with a single Kirschner wire (0.9 mm) and figure-of-eight wiring (20 G) was applied to group 1 (n = 9). Group 2 (n = 9) was stabilised with a combination of circumferential and figure-of-eight wiring techniques with orthopaedic wire (20 G). Group 3 (n = 9) was stabilised with the same technique as group 2, but with #2 FiberWire. The knee joints were positioned and fixed in the neutral standing angle (135°) and tested by applying tensile force. The loads at gap formations of 1, 2 and 3 mm were recorded, and the maximum failure load was measured in each group. RESULTS: In all the loads at displacement (1, 2 and 3 mm), group 3 was significantly stronger than groups 1 and 2, respectively (P <0.017). Group 3 (261.0 ± 52.8 N) showed significantly stronger fixation in the maximum load compared with group 1 (172.9 ± 45.6 N) (P <0.017). No significant difference was observed between groups 1 and 2 (204.9 ± 68.4 N) or between groups 2 and 3. CONCLUSIONS AND RELEVANCE: This study shows that the combination of circumferential and figure-of-eight techniques with FiberWire is more resistant to displacement than metal wire in this ex vivo feline patella fracture model.

Evaluation of LigaTie device for total lung lobectomy in small breed dogs - An ex vivo study.

This study aimed to evaluate an effectiveness of airway-sealing techniques used in total lung lobectomies in small dog breeds. Total lung lobectomies were performed on five canine cadavers weighing 2.5-8 kg. Airway-sealing techniques were performed on two randomly selected lobes per cadaver. The airway-sealing techniques consisted of traditional suture ligation, Endoloop, and LigaTie. After applying all surgical methods, bronchial stump was collected from the tongue and prepared. The effectiveness of each airway-sealing technique was evaluated by submerging the bronchial stumps in saline, followed by intubation to gradually increase the airway pressure to 80 cmH2O to identify the presence of air leakage in each lobe. Seven of the ten lobes in the traditional suture ligation group had a leakage; the leakages were fatal in three lobes. A single fatal leak occurred in the Endoloop group, while no leakage was noted in the LigaTie group. Therefore, the LigaTie technique had a higher statistical efficacy than the traditional suture ligation (p = 0.007). In conclusion, the LigaTie application reduced the incidence of air leakage following total lung lobectomies in small dog breeds.

Transhiatal esophagogastric anastomosis and postoperative monitoring of thoracic esophageal leiomyosarcoma in a dog.

A 12-year-old Maltese dog was referred to the Veterinary Teaching Hospital at Konkuk University because of severe regurgitation. Radiography, ultrasonography, and computed tomography showed a mass in the thoracic esophagus. Localization of the tumor, its extraluminal nature, the positioning and involvement of the stomach, and the lack of diffuse metastasis to the lung were factors considered when developing a surgical plan. A successful surgical procedure was performed. The final diagnosis was leiomyosarcoma. Following surgery, clinical signs were significantly reduced and postoperative complications were not observed. The dog died 25 days after surgery; we suspected that the death was due to postoperative stricture. Key clinical message: Surgical approaches that prioritize maintenance of low tension on the thoracic esophagus are important to prevent arrhythmia, bradycardia, and ventricular premature complex during esophagogastric anastomosis. In dogs with a small esophageal lumen anastomosis may lead to postoperative stricture.

Anastomose oesophago-gastrique trans-hiatal et suivi post-opératoire d'un léiomyosarcome oesophagien thoracique chez un chien. Un Bichon maltais âgé de 12 ans fut référé à l'hôpital vétérinaire d'enseignement de la Konkuk University à cause de régurgitations sévères. Les radiographies, l'échographie et la tomodensitométrie ont montré la présence d'une masse dans l'oesophage thoracique. La localisation de la tumeur, sa nature extra-luminaire, le positionnement et l'implication de l'estomac et l'absence de métastase diffuse au poumon étaient des facteurs considérés lors du développement d'un plan chirurgical. Une procédure chirurgicale réussie fut réalisée. Le diagnostic final était un léiomyosarcome. Suite à la chirurgie, les signes cliniques étaient significativement réduits et aucune complication post-opératoire ne fut observée. Le chien est décédé 25 jours après la chirurgie, nous soupçonnons que la mort était due à un rétrécissement post-opératoire.Message clinique clé:Les approches chirurgicales qui priorisent le maintien de faible tension sur l'oesophage thoracique sont importantes pour prévenir l'arythmie, la bradycardie et un complexe ventriculaire prématuré lors d'une une anastomose oesophagogastrique. Chez les chiens avec un petit lumen oesophagien l'anastomose peut entraîner un rétrécissement post-opératoire.(Traduit par Dr Serge Messier).

Up-regulation of MicroRNAs-21 and -223 in a Sprague-Dawley Rat Model of Traumatic Spinal Cord Injury.

In this experimental animal study, we examined alterations in the degree of transcription of two microRNAs (miRs)-miR-21 and -223-in a Sprague-Dawley (SD) rat model of traumatic spinal cord injury (TSCI). Depending on the volume of the balloon catheter (V), a total of 75 male SD rats were divided into the three experimental groups: the sham group (n = 25; V = 0 µL), the mild group (n = 25; V = 20 µL), and the severe group (n = 25; V = 50 µL). Successful induction of TSCI was confirmed on both locomotor rating scale at 4 h and 1, 3 and 7 days post-lesion and histopathologic examinations. Then, RNA isolation and quantitative polymerase chain reaction (PCR) were performed. No differences in the level of miR-21 expression were found at the first time point studied (4 h post-lesion) between the three experimental groups, whereas such differences were significant at all the other time points (P < 0.05). Moreover, there were significant alterations in the level of miR-223 expression at all time points studied through all the experimental groups (P < 0.05). Furthermore, locomotor rating scale scores had a linear relationship with the level of miR-21 expression (R2 = 0.4363, Y = 1.661X + 3.096) and that of miR-223 one (R2 = 0.9104, Y = 0.8385X + 2.328). Taken together, we conclude that up-regulation of miR-21 and -223 might be closely associated with progression and the early course of TSCI, respectively.

Platelet-rich plasma improves the therapeutic efficacy of mesenchymal stem cells by enhancing their secretion of angiogenic factors in a combined radiation and wound injury model.

Delayed wound healing after radiation exposure can cause serious cutaneous damage, and its treatment is a major clinical challenge. Although mesenchymal stem cells (MSCs) have emerged as a promising therapeutic agent in regenerative medicine, they alone do not produce satisfactory effects in a combined radiation and wound injury (CRWI) model. Here, we investigated the therapeutic effect of combined umbilical cord blood-derived (UCB)-MSCs and platelet-rich plasma (PRP) treatment on wound healing in a CRWI mouse model. First, we assessed the release of cytokines from UCB-MSCs cultured with PRP and observed changes in the expression of angiogenic factors. The angiogenic paracrine factors from UCB-MSCs cultured with PRP were assessed in human umbilical vein endothelial cells (HUVECs). To assess therapeutic efficacy, UCB-MSCs and PRP were topically implanted into a CRWT mouse model. Vascular endothelial growth factor (VEGF), a pro-angiogenic growth factor, urokinase-type plasminogen activator and contributor to VEGF-induced signalling were more highly expressed in conditioned media of UCB-MSCs cultured with PRP than in that of UCB-MSCs alone. Furthermore, conditioned media of UCB-MSCs cultured with PRP increased the formation of tube-like structures in HUVECs. Co-treatment of UCB-MSCs and PRP in a CRWI mouse model increased the wound closure rate and angiogenesis compared with an untreated irradiated group. Moreover, increased expression of VEGF and CD31 were observed in the wound tissue of co-treated mice compared with untreated irradiated mice. PRP stimulates the release of angiogenic factors from UCB-MSCs, and combined therapy of UCB-MSCs and PRP improves regeneration efficacy by enhancing angiogenesis in a CRWI model.

Experimental Tracheal Replacement Using 3-dimensional Bioprinted Artificial Trachea with Autologous Epithelial Cells and Chondrocytes.

Various treatment methods for tracheal defects have been attempted, such as artificial implants, allografts, autogenous grafts, and tissue engineering; however, no perfect method has been established. We attempted to create an effective artificial trachea via a tissue engineering method using 3D bio-printing. A multi-layered scaffold was fabricated using a 3D printer. Polycaprolactone (PCL) and hydrogel were used with nasal epithelial and auricular cartilage cells in the printing process. An artificial trachea was transplanted into 15 rabbits and a PCL scaffold without the addition of cells was transplanted into 6 rabbits (controls). All animals were followed up with radiography, CT, and endoscopy at 3, 6, and 12 months. In the control group, 3 out of 6 rabbits died from respiratory symptoms. Surviving rabbits in control group had narrowed tracheas due to the formation of granulation tissue and absence of epithelium regeneration. In the experimental group, 13 of 15 animals survived, and the histologic examination confirmed the regeneration of epithelial cells. Neonatal cartilage was also confirmed at 6 and 12 months. Our artificial trachea was effective in the regeneration of respiratory epithelium, but not in cartilage regeneration. Additional studies are needed to promote cartilage regeneration and improve implant stability.

3D Bioprinted Artificial Trachea with Epithelial Cells and Chondrogenic-Differentiated Bone Marrow-Derived Mesenchymal Stem Cells.

Tracheal resection has limited applicability. Although various tracheal replacement strategies were performed using artificial prosthesis, synthetic stents and tissue transplantation, the best method in tracheal reconstruction remains to be identified. Recent advances in tissue engineering enabled 3D bioprinting using various biocompatible materials including living cells, thereby making the product clinically applicable. Moreover, clinical interest in mesenchymal stem cell has dramatically increased. Here, rabbit bone marrow-derived mesenchymal stem cells (bMSC) and rabbit respiratory epithelial cells were cultured. The chondrogenic differentiation level of bMSC cultured in regular media (MSC) and that in chondrogenic media (d-MSC) were compared. Dual cell-containing artificial trachea were manufactured using a 3D bioprinting method with epithelial cells and undifferentiated bMSC (MSC group, n = 6) or with epithelial cells and chondrogenic-differentiated bMSC (d-MSC group, n = 6). d-MSC showed a relatively higher level of glycosaminoglycan (GAG) accumulation and chondrogenic marker gene expression than MSC in vitro. Neo-epithelialization and neo-vascularization were observed in all groups in vivo but neo-cartilage formation was only noted in d-MSC. The epithelial cells in the 3D bioprinted artificial trachea were effective in respiratory epithelium regeneration. Chondrogenic-differentiated bMSC had more neo-cartilage formation potential in a short period. Nevertheless, the cartilage formation was observed only in a localized area.

Transdermal water-in-oil nanocarriers of nitric oxide for triggering penile erection.

Men's sexual health can have significant effects on a man's self-esteem, sexual relationship and male reproductive functions. Although commercially available drugs (e.g., VIAGRA and CIALIS) show effective treatment of erectile dysfunction (ED), patients with severe ED fail to respond to these medicines. Topical nitric-oxide (NO) delivery to penis can be a painless, alternative solution with severe ED because NO triggers erection and diffuses to the trabecular arteries and smooth muscles in the penis. We here develop water-in-oil (W/O) nanoemulsions (NEs) that contain NO and can directly spread on the penis. We optimize NE formation conditions including hydrophilic-lipophilic balance (HLB) and ratio of oil, water and surfactants. Then, by spreading NEs on penis skin of intact middle aged dogs, we verify medication effects and safety of the NEs in vivo. The water-in-oil NEs can be a promising non-invasive medication for ED patients with low response to a phosphodiesterase type 5 (PDE5) inhibitor, thus increasing quality of life in the aging society.

Human umbilical cord blood-derived mesenchymal stromal cells and small intestinal submucosa hydrogel composite promotes combined radiation-wound healing of mice.

BACKGROUND AIMS: Mesenchymal stromal cells (MSCs) are a promising agent for treating impaired wound healing, and their therapeutic potential may be enhanced by employing extracellular matrix scaffolds as cell culture scaffolds or transplant cell carriers. Here, we evaluated the effect of human umbilical cord blood-derived (hUCB)-MSCs and a porcine small intestinal submucosa (SIS)-derived extracellular matrix scaffold in a combined radiation-wound mouse model of impaired wound healing. METHODS: hUCB-MSCs and SIS hydrogel composite was applied to the excisional wound of whole-body irradiated mice. Assessment of wound closing and histological evaluation were performed in vivo. We also cultured hUCB-MSCs on SIS gel and examined the angiogenic effect of conditioned medium on irradiated human umbilical vein endothelial cells (HUVECs) in vitro. RESULTS: hUCB-MSCs and SIS hydrogel composite treatment enhanced wound healing and angiogenesis in the wound site of mice. Conditioned medium from hUCB-MSCs cultured on SIS hydrogel promoted the chemotaxis of irradiated HUVECs more than their proliferation. The secretion of angiogenic growth factors hepatocyte growth factor, vascular endothelial growth factor-A and angiopoietin-1 from hUCB-MSCs was significantly increased by SIS hydrogel, with HGF being the predominant angiogenic factor of irradiated HUVECs. CONCLUSIONS: Our results suggest that the wound healing effect of hUCB-MSCs is enhanced by SIS hydrogel via a paracrine factor-mediated recruitment of vascular endothelial cells in a combined radiation-wound mouse model.

A Method for the Activation of Platelet-Rich Plasma via Bead Mill Homogenizer for Mesenchymal Stem Cell Culture.

Activated platelet-rich plasma (PRP) has been studied as a replacement for fetal bovine serum (FBS) in stem cell culture. However, current methods are time-consuming or require addition of exogenous substances to activate PRP, which have disadvantages in clinical applications. In this study, we developed a new method for PRP activation using a bead mill homogenizer and compared it with previous methods of PRP activation. PRP was prepared via a two-step centrifugation process and activated via calcium (Ca-PRP), freeze-thaw cycles (FT-PRP), or bead mill homogenizer processing (BM-PRP). Quantification of growth factors in PRP revealed that all forms of activated PRP released higher levels of platelet-derived growth factor-AB and transforming growth factor-ß1 than those in platelet-poor plasma; however, BM-PRP resulted in significantly higher levels of growth factors than those from Ca-PRP and FT-PRP. Next, we analyzed the ability of the various forms of PRP to stimulate proliferation, migration, and differentiation of umbilical cord blood-derived mesenchymal stem cells (UCB-MSCs). Our results showed that BM-PRP significantly increased proliferation and migration rates of UCB-MSCs while maintaining the phenotypical properties and stem cell abilities of MSCs. Therefore, the developed method could be suitable for PRP activation, and the BM-activated PRP could be an adequate replacement for FBS in stem cell culture.

Primary intrapelvic hemangiosarcoma in a dog.

A 12-year-old, spayed female Schnauzer presented with constipation. A mass was observed in the pelvic cavity, and metastasis was not identified. Mass resection was performed through celiotomy with pubic osteotomy, and hemangiosarcoma was diagnosed. At 10 weeks post-operatively, the patient died of multiple metastasis. Primary intrapelvic hemangiosarcoma is rare in dogs.

Expression of neurotrophic factors in injured spinal cord after transplantation of human-umbilical cord blood stem cells in rats.

We induced percutaneous spinal cord injuries (SCI) using a balloon catheter in 45 rats and transplanted human umbilical cord blood derived mesenchymal stem cells (hUCB-MSCs) at the injury site. Locomotor function was significantly improved in hUCB-MSCs transplanted groups. Quantitative ELISA of extract from entire injured spinal cord showed increased expression of brain-derived neurotrophic factor (BDNF), nerve growth factor (NGF) and neurotrophin-3 (NT-3). Our results show that treatment of SCI with hUCB-MSCs can improve locomotor functions, and suggest that increased levels of BDNF, NGF and NT-3 in the injured spinal cord were the main therapeutic effect.

Abnormal changes in both mandibular salivary glands in a dog: Non-mineral radiopaque sialoliths.

A 10-year-old Maltese dog was presented with a firm mass on the left side of his neck. Physical examination confirmed a firm mass in the left and a submandibular swelling in the right cervical region. Sialolithiasis and associated sialocele in both mandibular salivary glands were suspected and bilateral sialoadenectomy was performed. The stones were identified as non-mineral sialoliths.

Changements anormaux dans les deux glandes salivaires mandibulaires chez un chien : sialolithes radiopaques non minéraux. Un chien Maltais âgé de 10 ans a été présenté avec une masse ferme du côté droit du cou. L'examen physique a confirmé une masse ferme dans l'enflure gauche et sous-mandibulaire dans la région cervicale droite. La sialolithiase et une sialocèle connexe dans les deux glandes salivaires mandibulaires ont été suspectées et une sialoadénectomie bilatérale a été réalisée. Les pierres ont été identifiées comme des sialolithes non minéraux.(Traduit par Isabelle Vallières).

Quantitative measurement of influenza virus replication using consecutive bronchoalveolar lavage in the lower respiratory tract of a ferret model.

The ferret is an established animal model of influenza virus infection. Although viral replication in the upper respiratory tract is usually measured with consecutively collected nasal washes, daily evaluation of viral replication in the lung is limited because a large numbers of ferrets need to be sacrificed at consecutive time points. To overcome this limitation, we performed a virus quantification assay using bronchoalveolar lavage (BAL) fluid. This non-invasive BAL technique allows consecutive quantification of virus replication in the lungs of living ferrets. Our method can be used for the longitudinal evaluation of virus tropism in the lower respiratory tract.

Dose-dependent influence of short-term intermittent ethanol intoxication on cerebral neurochemical changes in rats detected by ex vivo proton nuclear magnetic resonance spectroscopy.

The aim of this study was to quantitatively assess the effects of short-term intermittent ethanol intoxication on cerebral metabolite changes among sham controls (CNTL), low-dose ethanol (LDE)-exposed, and high-dose ethanol (HDE)-exposed rats, which were determined with ex vivo high-resolution spectra. Eight-week-old male Wistar rats were divided into three groups. Twenty rats in the LDE (n=10) and the HDE (n=10) groups received ethanol doses of 1.5 and 2.5 g/kg, respectively, through oral gavage every 8h for 4days. At the end of the 4-day intermittent ethanol exposure, one-dimensional ex vivo 500-MHz ¹H nuclear magnetic resonance spectra were acquired from 30 samples of the frontal cortex region (from the three groups). Normalized total N-acetylaspartate (tNAA: NAA+NAAG [N-acetylaspartyl-glutamate]), GABA, and glutathione (GSH) levels were significantly lower in the frontal cortex of the HDE-exposed rats than that of the LDE-exposed rats. Moreover, compared to the CNTL group, the LDE rats exhibited significantly higher normalized GABA levels. The six pairs of normalized metabolite levels were positively (+) or negatively (-) correlated in the rat frontal cortex as follows: tNAA and GABA (+), tNAA and aspartate (Asp) (+), myo-Inositol (mIns) and Asp (-), mIns and alanine (+), mIns and taurine (+), and mIns and tNAA (-). Our results suggested that short-term intermittent ethanol intoxication might result in neuronal degeneration and dysfunction, changes in the rate of GABA synthesis, and oxidative stress in the rat frontal cortex. Our ex vivo(1)H high-resolution magic angle spinning nuclear magnetic resonance spectroscopy results suggested some novel metabolic markers for the dose-dependent influence of short-term intermittent ethanol intoxication in the frontal cortex.

Improved rat spinal cord injury model using spinal cord compression by percutaneous method.

Here, percutaneous spinal cord injury (SCI) methods using a balloon catheter in adult rats are described. A balloon catheter was inserted into the epidural space through the lumbosacral junction and then inflated between T9-T10 for 10 min under fluoroscopic guidance. Animals were divided into three groups with respect to inflation volume: 20 µL (n = 18), 50 µL (n = 18) and control (Fogarty catheter inserted but not inflated; n = 10). Neurological assessments were then made based on BBB score, magnetic resonance imaging and histopathology. Both inflation volumes produced complete paralysis. Gradual recovery of motor function occurred when 20 µL was used, but not after 50 µL was applied. In the 50 µL group, all gray and white matter was lost from the center of the lesion. In addition, supramaximal damage was noted, which likely prevented spontaneous recovery. This percutaneous spinal cord compression injury model is simple, rapid with high reproducibility and the potential to serve as a useful tool for investigation of pathophysiology and possible protective treatments of SCI in vivo.

Percutaneous transplantation of human umbilical cord-derived mesenchymal stem cells in a dog suspected to have fibrocartilaginous embolic myelopathy.

The use of human umbilical cord blood-derived mesenchymal stem cells for cell transplantation therapy holds great promise for repairing spinal cord injury. Here we report the first clinical trial transplantation of human umbilical cord (hUCB)-derived mesenchymal stem cells (MSCs) into the spinal cord of a dog suspected to have fibrocartilaginous embolic myelopathy (FCEM) and that experienced a loss of deep pain sensation. Locomotor functions improved following transplantation in a dog. Based on our findings, we suggest that transplantation of hUCB-derived MSCs will have beneficial therapeutic effects on FCEM patients lacking deep pain sensation.

Evaluation of a canine small intestinal submucosal xenograft and polypropylene mesh as bioscaffolds in an abdominal full-thickness resection model of growing rats.

We evaluated the biological scaffold properties of canine small intestinal submucosa (SIS) compared to a those of polypropylene mesh in growing rats with full-thickness abdominal defects. SIS is used to repair musculoskeletal tissue while promoting cell migration and supporting tissue regeneration. Polypropylene mesh is a non-resorbable synthetic material that can endure mechanical tension. Canine SIS was obtained from donor German shepherds, and its porous collagen fiber structure was identified using scanning electron microscopy (SEM). A 2.50-cm(2) section of canine SIS (SIS group) or mesh (mesh group) was implanted in Sprague-Dawley rats. At 1, 2, 4, 12, and 24 weeks after surgery, the implants were histopathologically examined and tensile load was tested. One month after surgery, CD68+ macrophage numbers in the SIS group were increased, but the number of CD8+ T cells in this group declined more rapidly than that in rats treated with the mesh. In the SIS group, few adhesions and well-developed autologous abdominal muscle infiltration into the SIS collagen fibers were observed. No significant differences in the tensile load test results were found between the SIS and mesh groups at 24 weeks. Canine SIS may therefore be a suitable replacement for artificial biological scaffolds in small animals.

Virus-like particle vaccine protects against H3N2 canine influenza virus in dog.

In the present study, virus-like particles (VLPs) were evaluated as a candidate veterinary vaccine against canine influenza virus (CIV) subtype H3N2. Specific pathogen-free (SPF) beagle dogs received a single injection of a VLP vaccine containing hemagglutinin (HA) and M1 protein of CIV H3N2 (H3 HA VLP). The vaccine was tested at 3 different doses with an adjuvant and 1 dose without an adjuvant. To evaluate the immunogenicity and protective efficacy of the H3 HA VLP vaccine, we performed hemagglutination inhibition tests to determine serological immune responses and conducted challenge studies using SPF beagle dogs. The addition of Montanide ISA 25 adjuvant significantly increased the immunogenicity of the H3 HA VLP vaccine. The experimental infection study showed that a single dose of H3 HA VLP vaccine induced protection against wild-type virus challenge in dogs. These results provide support for continued development of the VLP as an animal vaccine against influenza virus.