Equine grass sickness is associated with major abnormalities in the ultrastructure of skeletal neuromuscular junctions

BACKGROUND

Equine grass sickness (EGS) is a frequently fatal multisystem neuropathy of equids. The aetiology is unknown; proposed causes include toxicoinfection with Clostridium botulinum and a mycotoxicosis. The effect of EGS on the organisation and structural integrity of the skeletal neuromuscular junction (NMJ), the target of botulinum neurotoxins (BoNTs), is unknown.

OBJECTIVES

To compare the organisation and structural integrity of skeletal NMJs from EGS horses, control horses and one horse with a presumptive diagnosis of botulism.

STUDY DESIGN

Blinded, retrospective case control.

METHODS

NMJs in samples of diaphragm or intercostal muscle from six EGS horses, three control horses and one equine botulism case were compared using electron microscopy, morphometry and confocal light microscopy.

RESULTS

A significantly higher percentage of EGS NMJs had abnormal morphology (EGS 72.2%, 95% CI 55.6-84.4; Controls 6.9%, 1.7-23.8; OR 35.1, 8.47-244.8; p < 0.001). EGS NMJs had a significantly lower mean volume fraction occupied by synaptic vesicles (SVs) (EGS 18.7%, 12.6-28.0; Controls 36.3%, 20.8-63.4; p = 0.024). EGS NMJs had evidence of accelerated SV exocytosis and SV depletion, accumulation of neurofilament-like material in terminal boutons and/or bouton degeneration. NMJs from the botulism horse had dense packing of SVs towards the presynaptic membrane active zone, consistent with BoNT intoxication, but had absence of the abnormalities identified in EGS NMJs.

MAIN LIMITATIONS

Group sizes were limited by difficulties obtaining suitably processed samples. Ages of control and EGS horses differed. Botulism was diagnosed based on clinical and post mortem findings.

CONCLUSIONS

EGS is associated with major changes in skeletal NMJ ultrastructure that are inconsistent with the effects of BoNTs. SV depletion may reflect increased exocytosis coupled with reduced repopulation of SVs via anterograde axonal transport and endocytosis, consistent with the action of an excitatory presynaptic toxin and/or neurotransmitter reuptake inhibitor. Skeletal NMJs represent a previously unrecognised target for the toxin that causes EGS.

Endoscope and image-guided ventral bulla osteotomy in the dog: A cadaveric and patient study

BACKGROUND

Surgery of the bulla in the dog can be difficult and associated with suboptimal resolution of disease and risk of complications, particularly in treatment of cholesteatoma. We explored use of image guidance and endoscopic assistance in ventral bulla osteotomy (VBO), initially with cadaveric studies and subsequently on dogs with cholesteatoma.

METHODS

For surgical approach we used cone beam CT with an optical image navigation system. For endoscopic surgery we used 4 mm and 2.7 mm diameter endoscopes and a camera viewing system, with micro-instruments for dissection.

RESULTS

Image guidance allowed us to accurately identify and approach the bulla in cadavers (n = 2) and patients (n = 2). The endoscope enabled us to define detailed endoscopic anatomy in cadaveric canine heads (n = 15), and in patients (n = 5) it enabled reliable and safe removal of pathological tissue.

CONCLUSION

Image and endoscopic assistance could be a significant advance to the reliability and safety of VBO. Our techniques may be applicable to other indications and species.

Lumpy Skin Disease Is Characterized by Severe Multifocal Dermatitis With Necrotizing Fibrinoid Vasculitis Following Experimental Infection

Lumpy skin disease is a high-consequence disease in cattle caused by infection with the poxvirus lumpy skin disease virus (LSDV). The virus is endemic in most countries in Africa and an emerging threat to cattle populations in Europe and Asia. As LSDV spreads into new regions, it is important that signs of disease are recognized promptly by animal caregivers. This study describes the gross, microscopic, and ultrastructural changes that occur over time in cattle experimentally challenged with LSDV. Four calves were inoculated with wildtype LSDV and monitored for 19 to 21 days. At 7 days after inoculation, 2 of the 4 cattle developed multifocal cutaneous nodules characteristic of LSD. Some lesions displayed a targetoid appearance. Histologically, intercellular and intracellular edema was present in the epidermis of some nodules. Occasional intracytoplasmic inclusion bodies were identified in keratinocytes. More severe and consistent changes were present in the dermis, with marked histiocytic inflammation and necrotizing fibrinoid vasculitis of dermal vessels, particularly the deep dermal plexus. Chronic lesions consisted of full-thickness necrosis of the dermis and epidermis. Lesions in other body organs were not a major feature of LSD in this study, highlighting the strong cutaneous tropism of this virus. Immunohistochemistry and electron microscopy identified LSDV-infected histiocytes and fibroblasts in the skin nodules of affected cattle. This study highlights the noteworthy lesions of LSDV and how they develop over time.

Cutaneous Vasculopathy and Pulmonary Thromboembolism in an Unstable Diabetic Cat

A 6-year-old, male-neutered, domestic short-haired cat was referred for further management of a 3-month history of uncontrolled diabetes mellitus. The cat visited the hospital on 3 occasions during a 3-week time period. Hyperglycemia was documented at all visits. The cat initially presented with evidence of hypovolemia, cranial abdominal pain, and dehydration. Moderate hyperglycemia, mild ketonemia, and severe hypokalemia were documented. A 3 × 2 cm skin lesion with associated alopecia and erythema was first noticed at a routine follow-up examination (visit 2) 1 week later. A diagnosis of diabetic ketoacidosis was made 6 days later. The previously identified skin lesion now measured 6 × 2.5 cm. Two episodes of respiratory distress were identified at this visit, with no evidence of cardiac or pulmonary pathology. The cat developed a moderate anemia (packed cell volume 16 %, total solids 7.9 g/dL) on the fifth day of hospitalization. Fluid therapy, electrolyte supplementation, regular insulin, anti-emetic, and analgesia medications were administered during visits 1 and 3. Due to development of anemia, suspected pulmonary thromboembolism events and progression of skin lesions, euthanasia was elected. A diagnosis of cutaneous vasculopathy with secondary ischemic necrosis was made postmortem and pulmonary thromboembolism was confirmed. To the authors' knowledge, this is the first report of cutaneous vasculopathy and pulmonary thromboembolism in a cat with confirmed diabetes mellitus, warranting further research to assess if hypercoagulability is common in this patient population, as routine thromboprophylaxis and anticoagulation may be potentially indicated.

Effect of Stifle Flexion Angle on the Repeatability of Real-Time Elastosonography of the Patellar Ligament in Medium- to Large-Breed Dogs

OBJECTIVE

 The aims of this study were to describe the elastosonographic findings of the patellar ligament in healthy dogs >15 kg in different positions and determine the most appropriate stifle angle to perform elastosonography of the patellar ligament.

STUDY DESIGN

 Eighteen clinically healthy dogs, weighing >15 kg, were prospectively recruited. B-mode ultrasound and real-time elastosonography of both patellar ligaments were performed on days 0 and 14. Elastosonography examinations were performed with the stifle in four positions: standing position, lateral recumbency with the stifle positioned at 135 degrees extension and in full passive flexion and extension.

RESULTS

 The percentage hardness of the patellar ligament was significantly lower when the elastosonographic examination was performed with the dog standing, compared with the other positions (p < 0.005). The variability in the elastosonography readings for each stifle position was lowest when the dog was standing (89.32%).

CONCLUSION

 Elastosonography is a feasible technique for evaluating the elasticity of the normal canine patellar ligament in dogs >15 kg and would be a useful technique for investigating the mechanical changes within the patellar ligament following stifle surgery. Elastosonography of the patellar ligament should be performed with the dog standing to provide the most accurate elastosonograms with lowest variability between readings.

Brunner's gland hyperplasia in a geriatric chimpanzee (Pan troglodytes), an infrequently reported lesion

Benign duodenal tumours have very rarely been reported in captive non-human primates and are also rare in human beings. Brunner's gland hyperplasia has not been fully described in a non-human primate. Here, we report Brunner's gland hyperplasia in a geriatric chimpanzee, which was an incidental finding during post-mortem examination.

Naturally-Occurring Canine Mammary Tumors as a Translational Model for Human Breast Cancer

Despite extensive research over many decades, human breast cancer remains a major worldwide health concern. Advances in pre-clinical and clinical research has led to significant improvements in recent years in how we manage breast cancer patients. Although survival rates of patients suffering from localized disease has improved significantly, the prognosis for patients diagnosed with metastatic disease remains poor with 5-year survival rates at only 25%. In vitro studies using immortalized cell lines and in vivo mouse models, typically using xenografted cell lines or patient derived material, are commonly used to study breast cancer. Although these techniques have undoubtedly increased our molecular understanding of breast cancer, these research models have significant limitations and have contributed to the high attrition rates seen in cancer drug discovery. It is estimated that only 3-6% of drugs that show promise in these pre-clinical models will reach clinical use. Models that can reproduce human breast cancer more accurately are needed if significant advances are to be achieved in improving cancer drug research, treatment outcomes, and prognosis. Canine mammary tumors are a naturally-occurring heterogenous group of cancers that have several features in common with human breast cancer. These similarities include etiology, signaling pathway activation and histological classification. In this review article we discuss the use of naturally-occurring canine mammary tumors as a translational animal model for human breast cancer research.

Neutrophilia is associated with a poorer clinical outcome in dogs with chronic hepatitis

BACKGROUND

Liver disease is a common cause of morbidity and mortality in dogs. Currently, it is challenging to prognosticate in these cases. The aim of this study was to evaluate the utility of the haematological variables in dogs with chronic hepatitis.

METHODS

Dogs with chronic hepatitis confirmed on histopathology had presenting haematological values retrospectively obtained and evaluated against survival time. Eighty-two dogs met the inclusion criteria and their data analysed.

RESULTS

Neutrophilic patients, with a count greater than 12×10⁹/l, controlled for sex and age, had a shorter survival time (P≤0.01). In dogs, neutrophilia at presentation predicted a poor outcome, whereas the other haematological parameters were not prognostically informative. When the dogs were split into even quarters on the basis of their neutrophil count, those within the higher quartiles had poorer survival times. Neutrophilia was associated with a poorer survival time in comparison to those patients with a lower count.

CONCLUSION

The relationship between neutrophils, inflammation and clinical outcome is deserving of future study in dogs with chronic hepatitis.

Biocompatibility of common implantable sensor materials in a tumor xenograft model

Real-time monitoring of tumor microenvironment parameters using an implanted biosensor could provide valuable information on the dynamic nature of a tumor's biology and its response to treatment. However, following implantation biosensors may lose functionality due to biofouling caused by the foreign body response (FBR). This study developed a novel tumor xenograft model to evaluate the potential of six biomaterials (silicon dioxide, silicon nitride, Parylene-C, Nafion, biocompatible EPOTEK epoxy resin, and platinum) to trigger a FBR when implanted into a solid tumor. Biomaterials were chosen based on their use in the construction of a novel biosensor, designed to measure spatial and temporal changes in intra-tumoral O2 , and pH. None of the biomaterials had any detrimental effect on tumor growth or body weight of the murine host. Immunohistochemistry showed no significant changes in tumor necrosis, hypoxic cell number, proliferation, apoptosis, immune cell infiltration, or collagen deposition. The absence of biofouling supports the use of these materials in biosensors; future investigations in preclinical cancer models are required, with a view to eventual applications in humans. To our knowledge this is the first documented investigation of the effects of modern biomaterials, used in the production of implantable sensors, on tumor tissue after implantation. © 2018 The Authors. Journal of Biomedical Materials Research Part B: Applied Biomaterials published by Wiley Periodicals, Inc. J Biomed Mater Res Part B, 2018. © 2018 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 107B: 1620-1633, 2019.

Systemic Yersinia pseudotuberculosis as a Cause of Osteomyelitis in a Captive Ring-tailed Lemur (Lemur catta)

Yersinia pseudotuberculosis and Yersinia enterocolitica are ubiquitous pathogens with wildlife and domestic animal reservoirs. Outbreaks of 'non-plague' yersiniosis in man and non-human primates are reported frequently (including zoological specimens and research breeding colonies) and are usually characterized by enteritis, mesenteric lymphadenitis and occasionally organ abscessation. In people, non-septic reactive arthritis is a common sequela to yersiniosis. However, there have been rare reports in people of septic arthritis and osteomyelitis because of active systemic infection with Y. pseudotuberculosis. Osteomyelitis has also been reported rarely in historical yersiniosis outbreaks in farmed turkeys in England and the USA. This paper reports the first case of osteomyelitis caused by systemic infection with Y. pseudotuberculosis O:1 in a non-human primate, a captive ring-tailed lemur (Lemur catta). The lemur had a short clinical history of hyporexia and weight loss with reduction in mobility, especially of the left hindlimb. On post-mortem examination there was evidence of multi-organ abscessation. In addition, severe necrosis, inflammation and large bacterial colonies were present in the musculature, periosteum and bone marrow in the hip, ribs and a vertebra at the cervicothoracic junction. Osteomyelitis should be considered as a rare clinical presentation in non-human primates with systemic Y. pseudotuberculosis infection.

Fanconi Syndrome in Irish Wolfhound Siblings

Three juvenile male Irish wolfhound littermates presented with marked polyuria and polydipsia. The four female siblings were apparently unaffected. Diagnostic testing revealed glucosuria with normoglycemia, generalized aminoaciduria, hypokalemia and metabolic acidosis consistent with Fanconi syndrome. Renal ultrasonographic and histologic findings are presented. Cases were managed with a supplementation regimen based on a treatment protocol for Fanconi syndrome in basenjis. These dogs did not have angular limb deformities as documented previously in juvenile canine siblings with Fanconi syndrome. Fanconi syndrome has not been previously described in Irish wolfhound siblings.

A Rare Case of Deep Digital Flexor Tendinopathy following Centesis of the Navicular Bursa

Navicular bursa (NB) centesis is a common diagnostic and therapeutic procedure in equine practice. This case report documents the clinical, diagnostic imaging and histological findings in a horse with a suspected iatrogenic deep digital flexor tendon (DDFT) injury following centesis of the NB via a modified distal plantar approach (placement of two needles in a weight bearing position). Although it cannot be proven with absolute certainty, the authors believe that this is the first reported case where NB centesis is the likely cause of a DDFT lesion, and with magnetic resonance imaging performed both pre- and post-centesis. With this potential, though rare, complication of the procedure, alternative tendon sparing injection techniques should be considered prior to NB centesis in certain cases.

Thromboembolism in Dogs with Protein-Losing Enteropathy with Non-Neoplastic Chronic Small Intestinal Disease

Dogs with protein-losing enteropathy (PLE) are suggested to be at increased risk of developing thromboembolic events. However, with some exceptions, there are very few reports of thromboembolism in such dogs. This multicentre retrospective observational study describes a case series of thromboembolism (TE) in eight dogs with PLE secondary to non-neoplastic, chronic small intestinal disease. Seven dogs had poorly controlled PLE when the thromboembolic event occurred. Pulmonary thromboembolism (PTE) occurred in six dogs, while one dog developed splenic vein thrombosis and another had concurrent splenic vein and aortic TE. Six dogs died, all with PTE. Antithrombin activity was decreased in one of two dogs in which it was measured. Serum cobalamin and folate concentrations were measured in three dogs and cobalamin was subnormal in all three. Serum magnesium, measured in two dogs, was low in both. Dogs with uncontrolled chronic small intestinal disease and PLE are at risk for developing serious life-threatening TE, mostly PTE.

A Pre-clinical Animal Model of Trypanosoma brucei Infection Demonstrating Cardiac Dysfunction

African trypanosomiasis (AT), caused by Trypanosoma brucei species, results in both neurological and cardiac dysfunction and can be fatal if untreated. Research on the pathogenesis and treatment of the disease has centred to date on the characteristic neurological symptoms, whereas cardiac dysfunction (e.g. ventricular arrhythmias) in AT remains largely unstudied. Animal models of AT demonstrating cardiac dysfunction similar to that described in field cases of AT are critically required to transform our understanding of AT-induced cardiac pathophysiology and identify future treatment strategies. We have previously shown that T. brucei can interact with heart muscle cells (cardiomyocytes) to induce ventricular arrhythmias in ex vivo adult rat hearts. However, it is unknown whether the arrhythmias observed ex vivo are also present during in vivo infection in experimental animal models. Here we show for the first time the characterisation of ventricular arrhythmias in vivo in two animal models of AT infection using electrocardiographic (ECG) monitoring. The first model utilised a commonly used monomorphic laboratory strain, Trypanosoma brucei brucei Lister 427, whilst the second model used a pleomorphic laboratory strain, T. b. brucei TREU 927, which demonstrates a similar chronic infection profile to clinical cases. The frequency of ventricular arrhythmias and heart rate (HR) was significantly increased at the endpoint of infection in the TREU 927 infection model, but not in the Lister 427 infection model. At the end of infection, hearts from both models were isolated and Langendorff perfused ex vivo with increasing concentrations of the β-adrenergic agonist isoproterenol (ISO). Interestingly, the increased frequency of arrhythmias observed in vivo in the TREU 927 infection model was lost upon isolation of the heart ex vivo, but re-emerged with the addition of ISO. Our results demonstrate that TREU 927 infection modifies the substrate of the myocardium in such a way as to increase the propensity for ventricular arrhythmias in response to a circulating factor in vivo or β-adrenergic stimulation ex vivo. The TREU 927 infection model provides a new opportunity to accelerate our understanding of AT-related cardiac pathophysiology and importantly has the required sensitivity to monitor adverse cardiac-related electrical dysfunction when testing new therapeutic treatments for AT.

Primitive neuroectodermal tumour in a striped dolphin (Stenella coeruleoalba) with features of ependymoma and neural tube differentiation (Medulloepithelioma)

Primary brain tumours in cetaceans are rare with only four reported cases of intracranial tumours in the scientific literature. A juvenile female, striped dolphin live-stranded at Whitepark Bay, Co Antrim, Northern Ireland, UK, and died after an unsuccessful attempt at refloatation. Necropsy examination revealed a large, soft, non-encapsulated friable mass, which expanded and replaced the frontal lobes, corpus callosum and caudate nucleus of the brain and extended into the lateral ventricles, displacing the thalamus caudally. Microscopically, this comprised moderately pleomorphic neoplastic cells arranged variably in dense monotonous sheets, irregular streams, ependymal rosettes, 'ependymoblastomatous rosettes' and multilayered to pseudostratified tubules. Liquefactive necrosis, palisading glial cells, haemorrhage and mineralization were also observed. Immunohistochemically, the neoplastic cells expressed vimentin but not S100, glial fibrillary acidic protein, cytokeratin, neuron-specific enolase or synaptophysin. Based on these findings a diagnosis of primitive neuroectodermal tumour was made. Monitoring and recording such cases is crucial as neoplasia may be related to viral, carcinogenic or immunosuppressive chemical exposure and can ultimately contribute to assessing the ocean health.

Breed, age and gender distribution of dogs with chronic hepatitis in the United Kingdom

Standardised histological criteria are now available for the diagnosis of canine chronic hepatitis (CH). CH is common in dogs, but no studies have reported breed, age and gender distributions in the United Kingdom (UK). The objective of this study was to determine which breeds had an increased risk for developing CH in the UK and to report the age and gender distribution for those breeds. The databases of six veterinary histopathology laboratories were searched for cases with a histological diagnosis of CH according to standardised criteria. The breed, age and gender of dogs was recorded and compared to a control population to calculate the odds ratio and 95% confidence intervals for developing CH.

A total of 551 cases of CH were identified, consisting of 61 breeds. Nineteen breeds were represented by five or more cases. Breeds with an increased risk for developing CH included the American cocker spaniel, Cairn terrier, Dalmatian, Dobermann pinscher, English cocker spaniel, English springer spaniel, Great Dane, Labrador retriever and Samoyed. The median age at diagnosis for all breeds with CH was 8 years (range 7 months to 16 years). Dalmatians, Dobermann pinschers and English springer spaniels with CH were significantly younger than Cairn terriers, English cocker spaniels and Labrador retrievers with CH. Females were over-represented when all cases were examined together. In conclusion, several breeds in the UK have an increased risk of CH, some of which have not been previously reported.

Arrhythmogenic right ventricular cardiomyopathy as a cause of unexpected cardiac death in two horses

Postmortem and histological examination of the hearts from two horses, a five-year-old Clydesdale gelding and a 15-year-old cob gelding, revealed changes characteristic of arrhythmogenic right ventricular cardiomyopathy. In both cases, on gross examination, the right ventricular endocardium and interventricular septum were almost entirely replaced with a gelatinous yellow fibroareolar tissue. This tissue was histologically a combination of fibrous and adipose tissue that had replaced the normal myofibres and disrupted the Purkinje fibres.