Case report: Necrotizing leukomyelitis and meningitis in a Pomeranian.

A 2.5-year-old female entire Pomeranian dog was presented for acute paraparesis progressing within 2 days to paraplegia. General physical examination was unremarkable. Neurological examination showed paraplegia without nociception, a mass reflex upon testing perineal reflexes and withdrawal reflexes in the pelvic limbs and patellar hyperreflexia. Cutaneous trunci reflexes were absent caudal to the level of the 6th thoracic vertebra. Spinal hyperesthesia was present. Neuroanatomical localization was consistent with a T3-L3 myelopathy. Hematological and biochemical blood tests [including C-reactive protein (CRP)] were within reference ranges. MRI of the spinal cord from the level of the 1st thoracic vertebra to the sacrum revealed a patchy, ill-defined, moderate to marked T2W hyperintense, contrast enhancing intramedullary lesion extending from T1 to L4. Medical treatment based on a working diagnosis of meningomyelitis of unknown cause was initiated with corticosteroids and methadone based on pain scores. Prognosis was grave and after 3 days without return of nociception, the dog was euthanized according to the owners' wishes. Post-mortem histopathological examination of the brain and spinal cord yielded a morphological diagnosis of severe, segmental, bilateral and fairly symmetrical, necrotizing lymphohistiocytic leukomyelitis, with a non-suppurative angiocentric leptomeningitis. Some minor, focal, lymphocytic perivascular cuffing was found in the medulla oblongata as well, but otherwise there were no signs of brain involvement. No infectious causes were identified with ancillary tests. This case report underlines the importance of including meningomyelitis in the differential diagnosis list of dogs presented for acute progressive neurological signs referable to a myelopathy.

Interference between avian corona and influenza viruses: The role of the epithelial architecture of the chicken trachea.

Respiratory viral infections are among the major causes of disease in poultry. While viral dual infections are known to occur, viral interference in chicken airways is mechanistically hardly understood. The effects of infectious bronchitis virus (IBV) infection on tissue morphology, sialic acid (sia) expression and susceptibility of the chicken trachea for superinfection with IBV or avian influenza virus (AIV) were studied. In vivo, tracheal epithelium of chickens infected with IBV QX showed marked inflammatory cell infiltration and loss of cilia and goblet cells five days post inoculation. Plant lectin staining indicated that sialic acids redistributed from the apical membrane of the ciliated epithelium and the goblet cell cytoplasm to the basement membrane region of the epithelium. After administration of recombinant viral attachment proteins to slides of infected tissue, retained binding of AIV hemagglutinin, absence of binding of the receptor binding domain (RBD) of IBV M41 and partial reduction of IBV QX RBD were observed. Adult chicken trachea rings were used as ex vivo model to study the effects of IBV QX-induced pathological changes and receptor redistribution on secondary viral infection. AIV H9N2 infection after primary IBV infection was delayed; however, final viral loads reached similar levels as in previously uninfected trachea rings. In contrast, IBV M41 superinfection resulted in 1000-fold lower viral titers over the course of 48 h. In conclusion, epithelial changes in the chicken trachea after viral infection coincide with redistribution and likely specific downregulation of viral receptors, with the extend of subsequent viral interference dependent on viral species.

The contribution of the immune response to enhanced colibacillosis upon preceding viral respiratory infection in broiler chicken in a dual infection model.

Colibacillosis in chickens caused by avian pathogenic Escherichia coli (APEC) is known to be aggravated by preceding infections with infectious bronchitis virus (IBV), Newcastle disease virus (NDV) and avian metapneumovirus (aMPV). The mechanism behind these virus-induced predispositions for secondary bacterial infections is poorly understood. Here we set out to investigate the immunopathogenesis of enhanced respiratory colibacillosis after preceding infections with these three viruses. Broilers were inoculated intratracheally with APEC six days after oculonasal and intratracheal inoculation with IBV, NDV, aMPV or buffered saline. After euthanasia at 1 and 8 days post infection (dpi) with APEC, birds were macroscopically examined and tissue samples were taken from the trachea, lungs and air sacs. In none of the groups differences in body weight were observed during the course of infection. Macroscopic lesion scoring revealed most severe tissue changes after NDV-APEC and IBV-APEC infection. Histologically, persistent tracheitis was detected in all virus-APEC groups, but not after APEC-only infection. In the lungs, mostly APEC-associated transient pneumonia was observed. Severe and persistent airsacculitis was present after NDV-APEC and IBV-APEC infection. Bacterial antigen was detected by immunohistochemistry only at 1 dpi APEC, predominantly in NDV-APEC- and IBV-APEC-infected lungs. Higher numbers of CD4+ and CD8+ lymphocytes persisted over time in NDV-APEC- and IBV-APEC-infected tracheas, as did CD4+ lymphocytes in NBV-APEC- and IBV-APEC-infected air sacs. KUL01+ cells, which include monocytes and macrophages, and TCRγδ+ lymphocytes were observed mostly in lung tissue in all infected groups with transient higher numbers of KUL01+ cells over time and higher numbers of TCRγδ+ lymphocytes mainly at 8 dpi. qPCR analysis revealed mostly trends of transient higher levels of IL-6 and IFNγ mRNA in lung tissue after IBV-APEC and also NDV-APEC infection and persistent higher levels of IL-6 mRNA after aMPV-APEC infection. In spleens, transient higher levels of IL-17 mRNA and more persistent higher levels of IL-6 mRNA were observed after all co-infections. No changes in IL-10 mRNA expression were seen. These results demonstrate a major impact of dual infections with respiratory viruses and APEC, compared to a single infection with APEC, on the chicken respiratory tract and suggest that immunopathogenesis contributes to lesion persistence.

Feline and canine Merkel cell carcinoma: A case series and discussion on cellular origin.

Merkel cell carcinoma (MCC) is in humans and cats a malignant cutaneous neuroendocrine carcinoma, whereas in dogs it possibly has a more benign behaviour. It may be cytologically confused with round cell tumours such as lymphoma because of its striking cytomorphologic similarity. Although MCC is considered to arise from Merkel cells, recent findings indicated that primitive (epi-)dermal stem cells, early B-cells or dermal fibroblasts were the origin of human MCC. The aim of our study was to evaluate a possible lymphoid origin in feline and canine MCCs. Specific analysis of CD3, PAX-5, KIT and PARR assay were performed in 3 feline and 3 canine MCCs. All MCCs (6/6) were negative for CD3 and PAX-5. KIT was expressed in all MCCs (6/6). Assessment of clonality by PARR assay exhibited a polyclonal B- and T-cell receptor rearrangement in all five cases tested. In conclusion, a lymphoid origin of feline and canine MCCs could not be demonstrated. This is in contrast with human MCCs, that often express early B-cell lineage markers.

Guinea Fowl Coronavirus Diversity Has Phenotypic Consequences for Glycan and Tissue Binding.

Guinea fowl coronavirus (GfCoV) causes fulminating enteritis that can result in a daily death rate of 20% in guinea fowl flocks. Here, we studied GfCoV diversity and evaluated its phenotypic consequences. Over the period of 2014 to 2016, affected guinea fowl flocks were sampled in France, and avian coronavirus presence was confirmed by PCR on intestinal content and immunohistochemistry of intestinal tissue. Sequencing revealed 89% amino acid identity between the viral attachment protein S1 of GfCoV/2014 and that of the previously identified GfCoV/2011. To study the receptor interactions as a determinant for tropism and pathogenicity, recombinant S1 proteins were produced and analyzed by glycan and tissue arrays. Glycan array analysis revealed that, in addition to the previously elucidated biantennary di-N-acetyllactosamine (diLacNAc) receptor, viral attachment S1 proteins from GfCoV/2014 and GfCoV/2011 can bind to glycans capped with alpha-2,6-linked sialic acids. Interestingly, recombinant GfCoV/2014 S1 has an increased affinity for these glycans compared to that of GfCoV/2011 S1, which was in agreement with the increased avidity of GfCoV/2014 S1 for gastrointestinal tract tissues. Enzymatic removal of receptors from tissues before application of spike proteins confirmed the specificity of S1 tissue binding. Overall, we demonstrate that diversity in GfCoV S1 proteins results in differences in glycan and tissue binding properties.IMPORTANCE Avian coronaviruses cause major global problems in the poultry industry. As causative agents of huge economic losses, the detection and understanding of the molecular determinants of viral tropism are of ultimate importance. Here, we set out to study those parameters and obtained in-depth insight into the virus-host interactions of guinea fowl coronavirus (GfCoV). Our data indicate that diversity in GfCoV viral attachment proteins results in differences in degrees of affinity for glycan receptors, as well as altered avidity for intestinal tract tissues, which might have consequences for GfCoV tissue tropism and pathogenesis in guinea fowls.

Transmission Kinetics and histopathology induced by European Turkey Coronavirus during experimental infection of specific pathogen free turkeys.

Numerous viruses, mostly in mixed infections, have been associated worldwide with poult enteritis complex (PEC). In 2008 a coronavirus (Fr-TCoV 080385d) was isolated in France from turkey poults exhibiting clinical signs compatible with this syndrome. In the present study, the median infectious dose (ID50 ), transmission kinetics and pathogenicity of Fr-TCoV were investigated in 10-day-old SPF turkeys. Results revealed a titre of 104.88 ID50 /ml with 1 ID50 /ml being beyond the limit of genome detection using a well-characterized qRT-PCR for avian coronaviruses. Horizontal transmission of the virus via the airborne route was not observed however, via the oro-faecal route this proved to be extremely rapid (one infectious individual infecting another every 2.5 hr) and infectious virus was excreted for at least 6 weeks in several birds. Histological examination of different zones of the intestinal tract of the Fr-TCoV-infected turkeys showed that the virus had a preference for the lower part of the intestinal tract with an abundance of viral antigen being present in epithelial cells of the ileum, caecum and bursa of Fabricius. Viral antigen was also detected in dendritic cells, monocytes and macrophages in these areas, which may indicate a potential for Fr-TCoV to replicate in antigen-presenting cells. Together these results highlight the importance of good sanitary practices in turkey farms to avoid introducing minute amounts of virus that could suffice to initiate an outbreak, and the need to consider that infected individuals may still be infectious long after a clinical episode, to avoid virus dissemination through the movements of apparently recovered birds.

Clinicopathological findings in horses with a bi- or tripartite navicular bone.

BACKGROUND: Navicular bone partition is a rare condition reported in horses, which is during the evaluation of a lameness or prepurchase examination often misinterpreted for a parasagittal fracture. In this report, the clinicopathological findings of three cases of navicular bone partition are evaluated. The possible pathomechanisms underlying the condition are hypothesised, focusing on a potential origin of foetal vascular disturbance. This study is furthermore aiming at a clearer and earlier recognition of navicular bone partition, since this condition would finally predispose for a clinical lameness with a poor prognosis. CASE PRESENTATIONS: Case 1 was a 10-year-old Belgian Warmblood gelding with a Grade 3/5 chronic, recurrent left-forelimb lameness that had persisted for 4 months. Perineural palmar digital nerve block of the distal foot abolished the lameness. Radiographic examination revealed a bipartite navicular bone in the left forelimb. Unfortunately, the animal was lost to follow-up. Case 2 was a 7-year-old Quarter Horse stallion with a Grade 3/5 recurrent right forelimb lameness that had persisted for 2 years. The lameness switched to the contralateral left forelimb with a palmar digital nerve block. Radiographic examination identified a tripartite navicular bone in both forelimbs. Pathological examination additionally revealed chronic degenerative changes of the cartilage and subchondral bone with marked cystic changes. Case 3 was a 5-year-old Dutch Warmblood gelding with a Grade 3/5 recurrent left hindlimb lameness that had persisted for 6 months. Owing to the uncooperative behaviour of the horse, only a combined peroneal and tibial nerve block could be performed, which abolished the lameness. Radiographic examination revealed a bipartite navicular bone in the left hindlimb. Pathological examination showed a navicular bipartition in the left hindlimb, with microscopic changes comparable to those evident in Case 2; additionally, cartilage indentations were also found in the navicular bones of the right front- and hindlimb at a similar location as the partition site in the left hindlimb. CONCLUSIONS: It is speculated that a navicular bone partition has a congenital origin and is caused by vascular disturbance during foetal development. This may lead to aberrant endochondral ossification or the formation of multiple ossification centres resulting in navicular bone partitioning. In the adult horse, chronic repetitive biomechanical challenges at the partition sites may induce local degenerative changes with subchondral cyst formation and thus would cause a gradually developing chronic lameness with a poor prognosis.

Complete transposition of the aorta and pulmonary artery in a Belgian Blue crossbreed calf: a case report.

BACKGROUND: Complete transposition of the great arteries is a congenital cardiac malformation occasionally encountered in cattle and other species. The objective of the present report was to provide a detailed clinical, echocardiographic and post mortem description of a calf presenting with this condition. CASE PRESENTATION: A 6-week old male Belgian Blue cross-breed calf was examined for respiratory distress and exercise intolerance. The patient was bright, alert and responsive without any neurologic abnormalities but was exercise intolerant, had marked cyanosis, tachycardia, tachypnea, a pansystolic heart murmur as well as a bilaterally palpable thrill over the heart. Arterial blood gas analysis revealed marked hypoxemia (PaO(2)=23 mmHg, O(2)sat=41.1%), mild hypercapnia and compensated respiratory acidosis. Echocardiographic examination revealed a complete transposition of the great arteries in combination with a ventricular septal defect through which blood shunted bidirectionally. Cardiac catheterization confirmed that arterialization of blood of the systemic circulation solely occurred in the right ventricle through blood shunting from the left into the right ventricle. Results of post mortem examination are presented. CONCLUSION: Complete transposition of the great arteries is a cyanotic congenital anomaly repeatedly reported in calves that should be considered as differential diagnosis in patients presenting with hypoxemia more severe than commonly encountered with other congenital cyanotic heart conditions. We give a comprehensive summary of the clinical presentation, diagnostic work-up and post mortem examination of a Belgian Blue cross-breed calf with complete transposition of the great arteries.