Epidemiology and Survival of Dogs Diagnosed with Splenic Lymphoid Hyperplasia, Complex Hyperplasia, Stromal Sarcoma and Histiocytic Sarcoma.

Canine splenic fibrohistiocytic nodules traditionally encompassed benign lymphoid hyperplasia, complex hyperplasia, and malignant fibrous histiocytoma. The latter has been recently re-classified into histiocytic sarcoma and stromal sarcoma. Reliable indicators of post-splenectomy survival and demographic factors predisposing to the four types of nodules are not completely understood. This study aims to estimate frequency, survival times, and identify risk factors of splenectomized dogs diagnosed with lymphoid hyperplasia, complex hyperplasia, histiocytic sarcoma, and stromal sarcoma using medical records containing histopathological diagnosis from the VetCompass Australia database (1989−2018), which collects demographic, and clinical information from veterinary clinics. Out of 693 dogs, 315 were diagnosed with fibrohistiocytic nodules, mostly lymphoid hyperplasia (169/693, 24.4%), followed by stromal sarcoma (59/693, 8.5%), complex hyperplasia (55/693, 7.9%), and histiocytic sarcoma (32/693, 4.6%). Dogs aged 8−10 years were more likely to be diagnosed with histiocytic or stromal sarcoma than lymphoid hyperplasia. Dogs diagnosed with lymphoid hyperplasia had a longer survival time than those with other diagnoses (median > 2 years). Dogs diagnosed with histiocytic sarcoma had longer survival times (median 349 days) than stromal sarcoma (median 166 days). Results suggest that knowledge of the type of splenic fibrohistiocytic nodule, patients' age, and sex can be used to increase prognostic accuracy.

Fatal non-traumatic gas gangrene caused by Clostridium perfringens type A in a Siberian Husky dog.

An 8-y-old, castrated male Siberian Husky dog was admitted to an emergency clinic with acute collapse and severe swelling of both forelimbs, ventral thorax, and axillary region. The clinical assessment, with laboratory tests and radiologic investigation, confirmed severe subcutaneous emphysema and multi-organ failure. The animal died while receiving emergency treatment. On postmortem examination, Clostridium perfringens was isolated from the subcutaneous fluid and the effusion from the thoracic and abdominal cavities. Relevant histopathology findings included subcutaneous emphysema and multi-organ perivascular and intravascular, intralesional myriad 0.5-3-µm gram-positive rod bacteria, with no associated inflammation. Whole-genome sequencing and phylogenetic analysis identified C. perfringens type A. Virulence genes detected included cpa (alpha toxin), cadA (v-toxin), colA (collagenase A), nagH (hyaluronidase), nanH, nanI, nanJ (sialidases), and pfoa (perfringolysin). These virulence genes have previously been reported to act synergistically with alpha toxin in C. perfringens-mediated gas gangrene.

Rhinosinusitis in an Australian mare caused by Flavodon flavus, a recently recognized invasive fungal pathogen of the horse.

We describe herein the clinical, endoscopic, computed tomography (CT), pathologic, and microbiologic features of an infection caused by an under-recognized fungal pathogen, Flavodon flavus, in a 25-y-old Australian Quarter Horse. The horse had a unilateral obstructive nasal mass, resulting in stertor and dyspnea. On endoscopy, the mass was tan, multinodular, and completely obstructed the nasal passage. CT analysis revealed a large, soft tissue-attenuating and partially mineralized mass in the right nasal passage and dorsal-conchofrontal sinus, expanding into adjacent paranasal sinuses with associated bone lysis and rhinosinusitis. Histopathology of the mass on 2 occasions revealed suppurative inflammation initially, and pyogranulomatous inflammation subsequently. The inflammatory reaction surrounded numerous spherical fungal structures (~60-80 µm diameter) that stained positively on periodic acid-Schiff and Grocott methenamine silver stains. PCR for the fungal internal transcribed spacer 1 and 2 regions followed by Sanger sequencing on a cultured isolate identified the agent as F. flavus, which has only been reported previously as pathogenic in one horse in the United States, to our knowledge. Previous reports described this fungus as a nonpathogenic, environmental commensal fungus associated with insects and plants.

Canine CD117-Specific Antibodies with Diverse Binding Properties Isolated from a Phage Display Library Using Cell-Based Biopanning.

CD117 (c-Kit) is a tyrosine kinase receptor that is overexpressed in multiple dog tumors. There is 100% homology between the juxtamembrane domain of human and canine CD117, and many cancer-causing mutations occur in this region in both species. Thus, CD117 is an important target for cancer treatment in dogs and for comparative oncology studies. Currently, there is no monoclonal antibody (mAb) specifically designed to target the exposed region of canine CD117, although there exist some with species cross-reactivity. We panned a naïve phage display library to isolate antibodies against recombinant CD117 on whole cells. Several mAbs were isolated and were shown to bind recombinant canine CD117 at low- to sub-nanomolar affinity. Additionally, binding to native canine CD117 was confirmed by immunohistochemistry and by flow cytometry. Competitive binding assays also identified mAbs that competed with the CD117 receptor-specific ligand, the stem cell factor (SCF). These results show the ability of our cell-based biopanning strategy to isolate a panel of antibodies that have varied characteristics when used in different binding assays. These in vitro/ex vivo assessments suggest that some of the isolated mAbs might be promising candidates for targeting overexpressed CD117 in canine cancers for different useful applications.

Technical Skills Training for Veterinary Students: A Comparison of Simulators and Video for Teaching Standardized Cardiac Dissection.

The goal of the study was to evaluate alternative student-centered approaches that could replace autopsy sessions and live demonstration and to explore refinements in assessment procedures for standardized cardiac dissection. Simulators and videos were identified as feasible, economical, student-centered teaching methods for technical skills training in medical contexts, and a direct comparison was undertaken. A low-fidelity anatomically correct simulator approximately the size of a horse's heart with embedded dissection pathways was constructed and used with a series of laminated photographs of standardized cardiac dissection. A video of a standardized cardiac dissection of a normal horse's heart was recorded and presented with audio commentary. Students were allowed to nominate a preference for learning method, and students who indicated no preference were randomly allocated to keep group numbers even. Objective performance data from an objective structure assessment criterion and student perception data on confidence and competency from surveys showed both innovations were similarly effective. Evaluator reflections as well as usage logs to track patterns of student use were both recorded. A strong selection preference was identified for kinesthetic learners choosing the simulator and visual learners choosing the video. Students in the video cohort were better at articulating the reasons for dissection procedures and sequence due to the audio commentary, and student satisfaction was higher with the video. The major conclusion of this study was that both methods are effective tools for technical skills training, but consideration should be given to the preferred learning style of adult learners to maximize educational outcomes.

Pathological and Clinical Analysis of Vascular Catheterization Models in Rats, with Exploration of Interventions to Improve Clinical Tolerance.

Permanent vascular catheterization for intravascular access is one of the most commonly applied techniques used on rodents in pharmacology studies. However, use of the intravascular catheters is complicated by nontolerance due to thromboembolic disease and sepsis. We have undertaken an extensive pathologic and clinical analysis of an intravascular catheterization model in Wistar Han and Sprague-Dawley rats, with a particular focus on carotid artery catheterization with or without jugular vein catheterization, in order to define the pathologic mechanisms behind nontolerance and define clinical end points to ensure maximal animal welfare. Further, we have explored various potential solutions to increase the tolerance of the procedure. In these studies, indwelling catheters were found to cause a high degree of thromboembolic disease with infarction in the brain, cecal tip, and kidneys being the primary causes of nontolerance. Loss of greater than 10% body weight was determined to be the most sensitive indicator of nontolerance and was closely correlated with degree of renal parenchymal loss. Sepsis was noted as a very rare complication, indicating that routine aseptic surgical techniques are adequate for preventing this complication.

Global or Granulosa Cell-Specific Pten Mutations in Combination with Elevated FSH Levels Fail to Cause Ovarian Tumours in Mice.

Phosphatase and tensin homologue (PTEN) is a known tumour suppressor. To explore the role of Pten in ovarian tumorigenesis, we used transgenic (Tg) SOX2. Cre and AMH. Cre mouse models to direct global Pten haploinsufficiency (Pten +/-) or ovary-specific granulosa cell (GC) Pten disruption (Pten GC ). Pten mutant models were combined with progressively rising Tg-follicle-stimulating hormone (TgFSH) levels to study the tumorigenic potential of combined genetic/endocrine modification in vivo. Global Pten +/- mice exhibited grossly detectable tumours in multiple organs including uterine and mammary tissue and displayed reduced survival. Despite extra-ovarian tumorigenesis, Pten +/- females had no detectable ovarian tumours, although elevated corpus luteum numbers increased ovary size and estrous cycling was altered. Combined TgFSH/Pten +/- mice also had no ovarian tumours, but early survival was reduced in the presence of TgFSH. Ovary-specific Pten GC  ± TgFSH females exhibited no detectable ovarian or uterine tumours, and corpus luteum numbers and estrous cycling remained unchanged. The non-tumorigenic ovarian phenotypes in Pten +/- and Pten GC  ± TgFSH mice support the proposal that multi-hit genetic mutations (including ovarian and extra-ovarian tissue) initiate ovarian tumours. Our findings suggest that elevated FSH may reduce early cancer survival; however, the ovary remains remarkably resistant to Pten-induced tumorigenic changes even in the presence of uterine and reproductive cancers.

Intraosseous infusion of the distal phalanx compared to systemic intravenous infusion for marimastat delivery to equine lamellar tissue.

No validated laminitis drug therapy exists, yet pharmaceutical agents with potential for laminitis prevention have been identified. Many of these are impractical for systemic administration but may be effective if administered locally. This study compared intraosseous infusion of the distal phalanx (IOIDP) with systemic intravenous constant rate infusion (CRI) to determine which was more effective for lamellar marimastat delivery. Ultrafiltration probes were placed in both forefeet of five horses to collect lamellar interstitial fluid as lamellar ultrafiltrate (LUF). Marimastat solution (3.5 mg/mL) containing lidocaine (20 mg/mL) was infused by IOIDP at 0.15 mL/min for 12 h. After a 12 h wash-out, marimastat (3.5 mg/mL) and lidocaine were infused by constant rate infusion (CRI) at 0.15 mL/min for 12 h. LUF, plasma and lamellar tissue marimastat concentrations were quantified using UPLC-MS. Zymography was used to establish the inhibitory concentrations of marimastat for equine lamellar matrix metalloproteinases (MMPs). Data were analysed non-parametrically. There was no difference between the steady-state marimastat concentration in lamellar ultrafiltrate (LUF[M]) during IOIDP (139[88-497] ng/mL) and CRI (136[93-157] ng/mL). During IOIDP, there was no difference between marimastat concentrations in the treated foot (139[88-497] ng/mL), the untreated foot (91[63-154] ng/mL) and plasma (101[93-118] ng/mL). LUF[M] after IOIDP and CRI were >IC50 of lamellar MMP-2 and 9, but below the concentration considered necessary for in vivo laminitis prevention. Lamellar drug delivery during IOIDP was inconsistent and did not achieve higher lamellar marimastat concentrations than CRI. Modification or refinement of the IOIDP technique is necessary if it is to be consistently effective.

Ultrafiltration of equine digital lamellar tissue.

There are no experimentally validated pharmacological means of preventing laminitis; however, locally acting pharmaceutical agents with the potential to prevent laminitis have been identified. Demonstrating therapeutic drug concentrations in lamellar tissue is essential for evaluating the efficacy of these agents. The aim of this study was to develop an experimental technique for repeatedly sampling lamellar interstitial fluid. A technique for placing ultrafiltration probes was developed in vitro using 15 cadaver limbs. Subsequently, lamellar ultrafiltration probes were placed in one forelimb in six living horses. Interstitial fluid was collected continuously from the probes as ultrafiltrate for 4 (n = 4) or 14 days (n = 2). The rate of ultrafiltrate collection was calculated every 12 h. Biochemical analyses were performed on ultrafiltrate collected on night 1 (12-24 h post-implantation) and night 4 (84-96 h post-implantation). Sections surrounding the probe and control tissue from the contralateral limb were harvested, stained with H&E and Masson's trichrome and scored based on the tissue response to the probe. Ultrafiltration probes were placed in the lamellar tissue in all six horses. Ultrafiltrate was collected from these probes at 55 (30-63) µL/h (median [interquartile range]). Fluid production decreased significantly with time from night 3 onwards (P < 0.05). There was no significant change in the constituents of the ultrafiltrate between nights 1 and 4 (P > 0.05). The technique was well tolerated. This study demonstrates that ultrafiltration can be used to sample equine digital lamellar interstitial fluid, and has potential for measuring lamellar drug levels.

Venomous and poisonous Australian animals of veterinary importance: a rich source of novel therapeutics.

Envenomation and poisoning by terrestrial animals (both vertebrate and invertebrate) are a significant economic problem and health risk for domestic animals in Australia. Australian snakes are some of the most venomous animals in the world and bees, wasps, ants, paralysis ticks, and cane toads are also present as part of the venomous and poisonous fauna. The diagnosis and treatment of envenomation or poisoning in animals is a challenge and can be a traumatic and expensive process for owners. Despite the potency of Australian venoms, there is potential for novel veterinary therapeutics to be modeled on venom toxins, as has been the case with human pharmaceuticals. A comprehensive overview of envenomation and poisoning signs in livestock and companion animals is provided and related to the potential for venom toxins to act as therapeutics.

Mycobacterial trehalose dimycolate reprograms macrophage global gene expression and activates matrix metalloproteinases.

Trehalose 6,6'-dimycolate (TDM) is a cell wall glycolipid and an important virulence factor of mycobacteria. In order to study the role of TDM in the innate immune response to Mycobacterium tuberculosis, microarray analysis was used to examine gene regulation in murine bone marrow-derived macrophages in response to 90-µm-diameter polystyrene microspheres coated with TDM. A large number of genes, particularly those involved in the immune response and macrophage function, were up- or downregulated in response to these TDM-coated beads compared to control beads. Genes involved in the immune response were specifically upregulated in a myeloid differentiation primary response gene 88 (MyD88)-dependent manner. The complexity of the transcriptional response also increased greatly between 2 and 24 h. Matrix metalloproteinases (MMPs) were significantly upregulated at both time points, and this was confirmed by quantitative real-time reverse transcription-PCR (RT-PCR). Using an in vivo Matrigel granuloma model, the presence and activity of MMP-9 were examined by immunohistochemistry and in situ zymography (ISZ), respectively. We found that TDM-coated beads induced MMP-9 expression and activity in Matrigel granulomas. Macrophages were primarily responsible for MMP-9 expression, as granulomas from neutrophil-depleted mice showed staining patterns similar to that for wild-type mice. The relevance of these observations to human disease is supported by the similar induction of MMP-9 in human caseous tuberculosis (TB) granulomas. Given that MMPs likely play an important role in both the construction and breakdown of tuberculous granulomas, our results suggest that TDM may drive MMP expression during TB pathogenesis.

Ectopic brain tissue in the retina of a beagle dog: a case report and literature review.

Isolated ectopic brain tissue within the orbit is an extremely rare finding and has never been reported in dogs or other domestic species. In this case, a focal choristoma of ectopic grey matter-like tissue was present within the retina of a mature female beagle dog, and consisted of neurons and astrocytes as demonstrated respectively by microtubule-associated protein 2 and glial fibrillary acidic protein immunohistochemistry. The lesion was located within the optic fundus adjacent to the optic disk and surrounded by dysplastic retina. The case is presented with a review of literature on this rare entity.

Pathologic and virologic characterization of neuroinvasion by HSV-2 in a mouse encephalitis model.

Herpes simplex virus type 2 (HSV-2), a ubiquitous human pathogen associated with genital infections, is neurotropic. It establishes latent infections in local dorsal root ganglia from which it reactivates causing recurrent lesions and frequent episodes of viral shedding. Herpes simplex virus type 2 can also be transmitted from mother to child during birth, causing major neonatal complications including encephalitis. Animal models of HSV-2 genital infection are well described and used for testing of therapies; little is known about animal models of HSV-2-induced encephalitis. We analyzed the pathologic and immunohistochemical features of the nasal rostrum and brain tissue and correlated them with viral distribution in a mouse model of HSV-2 encephalitis induced by intranasal infection and examined viral replication in the brain tissue using quantitative polymerase chain reaction and traditional plaque assay. Our results suggest that the primary route for HSV-2 neuroinvasion after intranasal infection is via the trigeminal pathway, ultimately leading to infection of the brainstem and meningoencephalitis.