Four cases of a rare melanotic variant of malignant nerve sheath tumour (MNST) in dogs are described. All four cases presented with neurological clinical signs due to multicentric, intradural, intra- and extraparenchymal neoplasms that surrounded the spinal and cranial nerves and infiltrated the adjacent spinal cord and brain. The dogs were young (3 months to 3 years of age), all were female and four different breeds were represented. Characteristic histological features were interweaving fascicles of spindle-shaped cells, sometimes with an architecture reminiscent of Antoni A and B patterns. Some spindle cells showed prominent cytoplasmic melanin pigmentation and such cells were positive by Masson-Fontana stain. Immunohistochemistry performed in three cases was positive for S100 and vimentin, strongly positive for melan A in the melanized cells and negative for glial fibrillary acidic protein and periaxin. Non-melanized cells did not express melan A. Transmission electron microscopy findings in one case were consistent with a peripheral nerve sheath tumour and demonstrated cytoplasmic pre-melanosomes and melanosomes. Melanotic variants of MNSTs are rare in animals with only a solitary report of two previous canine cases in the literature.

Divergent differentiation is encountered frequently within human malignant peripheral nerve sheath tumours (MPNSTs). The new component is often a rhabdomyosarcoma, but in animals this specific form of divergent differentiation within MPNSTs has only been reported once (in a dog). Incisional wedge biopsy of a locally extensive, ventral abdominal wall mass, which extended from the dermis to the subcutis, from a 12-year-old female domestic shorthaired cat, was performed. The tissue was examined with routine haematoxylin and eosin staining and immunohistochemical methods. A malignant neoplasm with spindle and polygonal cell components and progression towards a rhabdomyosarcomatous phenotype was observed. Both neoplastic cell populations exhibited strong expression of vimentin and there was multifocal expression of S100 and desmin. There was strong cytoplasmic labelling for α-sarcomeric actin and muscle actin and weak labelling for myoglobin within the cells positive for desmin. There was multifocal positive nuclear labelling for myogenin. Glial fibrillary acidic protein, α-smooth muscle actin, microphthalmia-associated transcription factor and melanoma antigen recognized by T cells were not expressed. Microscopical features, aided by immunohistochemistry, identified a MPNST with progression towards a rhabdomyosarcomatous phenotype, a so-called 'triton tumour'. A Schwann cell component could account for the divergent patterns of growth, given the plasticity of the neural crest. Nerve sheath tumours have been reported in the skin and subcutis of cats and are a differential diagnosis of feline cutaneous spindle cell neoplasms.

A diffuse, chronic, superficial neocortical degeneration that resulted in atrophy was detected in five 1 to 2-year-old-dogs. Presenting neurologic signs included ataxia, dysphagia, blindness, and mentation changes. Magnetic resonance imaging on brains from 2 dogs demonstrated severe bilateral cerebrocortical atrophy and enlarged lateral and third ventricles. Grossly, multifocal, bilaterally symmetrical, extensive areas of neocortical brownish discoloration associated with atrophy of gyri and sulcal widening were recorded in the dorsal and lateral cerebral hemispheres in 3 dogs. Microscopically, in all dogs there was subacute to chronic superficial neocortical degeneration affecting all cerebral lobes, ranging from loss of the molecular layer to less frequent larger and deeper cavitations of variable size. Clinical signs probably resulted from a combination of primary neocortical degeneration and secondary degeneration in the corticobulbar and corticospinal tracts. The distribution pattern of gross and histologic cerebrocortical lesions suggests that this is a novel degenerative canine cerebral disease.

Several subtypes of canine meningioma are recognized. This report describes four canine meningiomas with previously unreported features. The four affected dogs were of different breeds. Three of the affected dogs were male and aged 7-10 years. In one dog, age and gender were not recorded. Meningiomas were located intracranially (three dogs) or within the vertebral canal (one dog). Two meningiomas resembled gemistocytic astrocytomas, while one had focal features of a rhabdoid tumour; these three meningiomas also contained amyloid deposits. The fourth tumour, a secretory meningioma, was rich in amianthoid fibres (i.e. unusual collagen deposits containing giant collagen fibres). All of these features are also described in human meningiomas.

A novel leukoencephalomyelopathy was identified in 73 mature male and female large captive felids between 1994 and 2005. While the majority of identified cases occurred in cheetahs (Acinonyx jubatus), the disease was also found in members of 2 other subfamilies of Felidae: 1 generic tiger (Panthera tigris) and 2 Florida panthers (Puma concolor coryi). The median age at time of death was 12 years, and all but 1 cheetah were housed in the United States. Characteristic clinical history included progressive loss of vision leading to blindness, disorientation, and/or difficulty eating. Neurologic deficits progressed at a variable rate over days to years. Mild to severe bilateral degenerative lesions were present in the cerebral white matter and variably and to a lesser degree in the white matter of the brain stem and spinal cord. Astrocytosis and swelling of myelin sheaths progressed to total white matter degeneration and cavitation. Large, bizarre reactive astrocytes are a consistent histopathologic feature of this condition. The cause of the severe white matter degeneration in these captive felids remains unknown; the lesions were not typical of any known neurotoxicoses, direct effects of or reactions to infectious diseases, or nutritional deficiencies. Leukoencephalomyelopathy was identified in 70 cheetahs, 1 tiger, and 2 panthers over an 11-year period, and to our knowledge, cases have ceased without planned intervention. Given what is known about the epidemiology of the disease and morphology of the lesions, an environmental or husbandry-associated source of neurotoxicity is suspected.

In order to compare the accuracy of MR sequences for diagnosis of meningeal disease, MR images of the brain, and histopathologic specimens including the meninges of 60 dogs were reviewed retrospectively by independent observers in a cross-sectional study. MR images included T1-weighted pre- and postgadolinium images, subtraction images, T2-weighted images, and T2-weighted fluid-attenuated inversion-recovery (FLAIR) images. Pathologic changes affected the pachymeninges in 16 dogs, leptomeninges in 35 dogs, and brain in 38 dogs. The meninges were normal in 12 dogs. Meninges were classified histopathologically as normal (grade 0), slightly or inconsistently affected (grade 1), or markedly affected (grade 2). When applying relaxed pathologic criteria (grades 0 and 1 considered normal), the results of ROC analysis (area under curve, AUC) were: T1-weighted postcontrast images 0.74; subtraction images 0.7; T2-weighted images 0.68; FLAIR images 0.56. The difference in AUC between T1-weighted postgadolinium images and FLAIR images was significant (P = 0.04). AUC for FLAIR images was not significantly different from 0.5. When applying strict pathologic criteria (only grade 0 considered normal), none of the MR sequences had AUC significantly different from 0.5. On the basis of T1-weighted postgadolinium images and subtraction images, correct anatomic classification of lesions occurred more often for pachymeningeal than leptomeningeal lesions (P < 0.001). Overall, MR imaging had low sensitivity for diagnosis of meningeal pathology in dogs, particularly for changes affecting the leptomeninges. Subtraction images had similar accuracy to T1-weighted postgadolinium images for meningeal lesions in dogs. T2-weighted FLAIR images appear to have limited diagnostic utility for meningeal lesions.

Protozoal merozoites were identified in the cerebrospinal fluid of two sheep with neurological disease in the UK. Polymerase chain reaction (PCR) identified the merozoites as Sarcocystis capracanis, a common protozoal pathogen of goats. This is the first report of this species infecting sheep and may represent an aberrant infection with sheep acting as dead end hosts, or alternatively could indicate that sheep are able to act as intermediate hosts for S. capracanis, widening the previously reported host range of this pathogen. It is possible that S. capracanis is a previously unrecognised cause of ovine protozoal meningoencephalitis (OPM) in the UK.

Veterinary RecordVolume 173, Issue 20 p. 502-502 Research Vacuolar meningioma: a new and rare variant of canine meningioma E. Scarpante DVM MRCVS, Corresponding Author E. Scarpante DVM MRCVS axanele82@libero.it Dick White Referrals, London Road, Six Mile Bottom, Cambridgeshire, CB8 0UH UKE-mail for correspondence: axanele82@libero.itSearch for more papers by this authorV. Palus DVM DipECVN, MRCVS, V. Palus DVM DipECVN, MRCVS Dick White Referrals, London Road, Six Mile Bottom, Cambridgeshire, CB8 0UH UKSearch for more papers by this authorB. A. Summers BVSc PhD MRCVS FRCPath, B. A. Summers BVSc PhD MRCVS FRCPath The Royal Veterinary College, Hawkshead Lane, North Mymms, Hatfield, Herts, AL9 7TA UKSearch for more papers by this authorA. Caine MA VetMB DipECVDI CertVDI MRCVS, A. Caine MA VetMB DipECVDI CertVDI MRCVS Dick White Referrals, London Road, Six Mile Bottom, Cambridgeshire, CB8 0UH UKSearch for more papers by this authorG. B. Cherubini DVM DipECVN MRCVS, G. B. Cherubini DVM DipECVN MRCVS Dick White Referrals, London Road, Six Mile Bottom, Cambridgeshire, CB8 0UH UKSearch for more papers by this author E. Scarpante DVM MRCVS, Corresponding Author E. Scarpante DVM MRCVS axanele82@libero.it Dick White Referrals, London Road, Six Mile Bottom, Cambridgeshire, CB8 0UH UKE-mail for correspondence: axanele82@libero.itSearch for more papers by this authorV. Palus DVM DipECVN, MRCVS, V. Palus DVM DipECVN, MRCVS Dick White Referrals, London Road, Six Mile Bottom, Cambridgeshire, CB8 0UH UKSearch for more papers by this authorB. A. Summers BVSc PhD MRCVS FRCPath, B. A. Summers BVSc PhD MRCVS FRCPath The Royal Veterinary College, Hawkshead Lane, North Mymms, Hatfield, Herts, AL9 7TA UKSearch for more papers by this authorA. Caine MA VetMB DipECVDI CertVDI MRCVS, A. Caine MA VetMB DipECVDI CertVDI MRCVS Dick White Referrals, London Road, Six Mile Bottom, Cambridgeshire, CB8 0UH UKSearch for more papers by this authorG. B. Cherubini DVM DipECVN MRCVS, G. B. Cherubini DVM DipECVN MRCVS Dick White Referrals, London Road, Six Mile Bottom, Cambridgeshire, CB8 0UH UKSearch for more papers by this author First published: 23 November 2013 https://doi.org/10.1136/vr.101548 Provenance: Not commissioned; externally peer reviewed Read the full textAboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat No abstract is available for this article. Volume173, Issue20November 2013Pages 502-502 RelatedInformation

A 9-month-old female Yucatan pig was euthanized after acute onset of paraplegia. Gross and microscopic examination revealed dorsal dissection of the nucleus of the L2–L3 intervertebral disk through the annulus fibrosus, extrusion of nucleus pulposus material through the overlying dura mater and into the spinal cord, and associated acute spinal hemorrhage and necrosis. This is, to the authors’ knowledge, the first reported case of intervertebral disk disease in swine.

Ependymal tumors are reported rarely in domestic animals. The aims of this study were to examine the clinical and pathologic features of ventricular and extraventricular ependymomas and subependymomas in 18 domestic cats examined between 1978 and 2011. Parameters examined included age, sex, breed, clinical signs, and macroscopic and histopathologic features. The mean age of affected cats was 9 years, 4 months; median age, 8.5 years. There were 8 female and 4 male cats, and 6 cats for which sex was not recorded. Breeds included 10 domestic shorthaired, 2 domestic longhaired, 1 Persian, and 1 Siamese. Clinical signs included altered mentation or behavior, seizures, circling, propulsive gait, generalized discomfort, and loss of condition. The tumors often formed intraventricular masses and usually arose from the lining of the lateral or third ventricles, followed by the fourth ventricle, mesencephalic aqueduct, and spinal cord central canal. Three tumors were extraventricular, forming masses within the cerebrum and adjacent subarachnoid space. Histologically, 15 tumors were classified as variants of ependymomas (classic, papillary, tanycytic, or clear cell) and 3 as subependymomas. Tumors were generally well demarcated; however, 6 ependymomas focally or extensively infiltrated the adjacent neural parenchyma. Characteristic perivascular pseudorosettes were observed in all ependymomas; true rosettes were less common. Some tumors had areas of necrosis, mineralization, cholesterol clefts, and/or hemorrhage. This cohort study of feline ependymal tumors includes subependymoma and primary extraventricular ependymoma, variants not previously described in the veterinary literature but well recognized in humans.

Within the human medical literature, retiform haemangioendothelioma (RHE) is an established and well-recognized histopathological variant of endothelial tumours, but to date RHE has not been reported in animals. These tumours are characterized by the presence of elongate, arborizing vascular channels lined by neoplastic endothelium with prominent, often bulging (‘hobnail’) nuclei supported by a dense collagenous matrix and accompanied by abundant lymphoplasmacytic inflammation. Immunohistochemically, the neoplastic cells typically express endothelial markers such as von Willebrand factor and CD31. Human RHEs are categorized as low-grade malignancies. This report describes two canine vascular tumours with features consistent with RHE. In both cases there was suspected or known widespread tumour metastasis.

Four cylindrical silicon tissue cages (TC, internal volume: 6.7 ± 0.11 cm(3)) were inserted subcutaneously in 29 young healthy cats. A mild inflammatory reaction was induced by intracaveal injection of 1 mL of a 2%λ-carrageenan solution. TC exudate was subsequently sampled at predetermined times (up to 120 h) to measure exudate leucocyte counts and the concentrations of protein and eicosanoids. TC remained in situ for 9-10 months and were well tolerated. Leucocyte counts peaked at 34 h (50.1 ± 57.6 × 10(3) cells/mm(3) ) and returned towards baseline after 72 h. Protein concentration increased from 26.2 ± 2.7 g/L to a peak of 35.9 ± 6.0 g/L at 12 h before returning to baseline at 48 h. Exudate prostaglandin (PG)E(2) concentration peaked at 24 h (11.7 ± 13.7 ng/mL) and returned to baseline by 120 h. Repeated collection of fluid from noninjected cages did not increase transudate PGE(2). Ketoprofen (2 mg/kg, subcutaneously) suppressed exudate PGE(2) at 24 h. The carrageenan-stimulated TC model is an ethical and novel means of investigating soft tissue inflammation in the cat, in which exudate PGE(2) acts as surrogate marker of cyclooxygenase-2 activity. This model will facilitate the investigation of in vivo pharmacokinetics and pharmacodynamics of anti-inflammatory drugs in this species.

A male Jack Russell terrier developed bilateral uveitis and glaucoma at 1 year of age. Since the ocular disease was painful and unresponsive to treatment, both globes were enucleated. Microscopical evaluation of one enucleated globe revealed panuveitis, with pigment dispersion and phagocytosis consistent with the ocular lesions of canine Vogt-Koyanagi-Harada (VKH)-like syndrome. Three years later the dog was represented with severe muscle disease and skin lesions. Due to rapid clinical deterioration the dog was humanely destroyed. Necropsy examination revealed lichenoid interface inflammation in the skin and mucous membranes, with pigmentary incontinence consistent with VKH-like syndrome and lymphocytic and histiocytic polymyositis with marked muscle atrophy. Canine VKH-like syndrome is an autoimmune disease that targets melanocyte antigens. Some human patients with VKH disease develop additional autoimmune diseases. To our knowledge this is the first reported case of polymyositis subsequent to VKH-like disease in a dog. In addition, VKH-like disease has not been previously reported in a Jack Russell terrier.

A five-year eight-month-old Maltese terrier was presented with a 3-week history of progressive paraparesis and pelvic limb ataxia. Neurological examination was consistent with a lesion involving the T3-L3 spinal cord segments. Myelogram and magnetic resonance imaging revealed a spherical, intradural-extramedullary mass lesion at T13/L1. A dorsal laminectomy, durotomy and debulking of the mass were performed. Histopathologic examination revealed a highly cellular tissue, most likely of mesenchymal origin, infiltrated by many lymphocytes, macrophages and neutrophils. The pathological diagnosis of an inflammatory pseudotumour was made. Postsurgical analgesia was achieved with opioids and 2 mg/kg carprofen twice daily for 5 days. When the histopathological diagnosis was made, a tapering course of 1 mg/kg prednisolone twice daily was prescribed, with dose reduction by approximately 50% every 4 to 6 weeks over a 4-month period. Magnetic resonance imaging was repeated at 22, 32 and 85 weeks postsurgery; no signs of regrowth could be detected and the patient recovered with residual mild paraparesis. Inflammatory pseudotumour has not been documented previously at this site in dogs and, although rare, should be considered in the differential diagnosis of a focal mass lesion affecting the spinal cord. Surgical debulking and immunomodulatory therapy can be curative.

Schwannomas are uncommonly recognized in horses. This study describes cutaneous schwannomas in 22 horses aged 8 to 25 years: 12 male, 7 female, and 3 of unknown sex. The horses had solitary cutaneous masses: 9 on the head, 3 on the neck, and the others on the shoulder, hip, thorax, abdomen, rump, extremities, or tail. The location of 1 tumor was unknown. The dermal tumors were well demarcated and expansile. Twelve had a multinodular pattern, whereas 10 formed a single nodule. Antoni A areas were observed in all tumors, and 10 tumors contained Antoni B areas. In Antoni A areas, the densely packed spindle-shaped neoplastic cells were arranged in short fascicles with nuclear palisading. In the hypocellular Antoni B areas, neoplastic cells were separated by abundant myxomatous stroma. Tumors commonly had hyalinization of stroma and vessel walls and ancient change. Cellular vacuolation was observed in 18 tumors. In all 22 cases, neoplastic cells were immunopositive for S100 protein. Expression of laminin and glial fibrillary acidic protein was observed in all 6 tumors evaluated by immunohistochemistry for these markers. One tumor was examined ultrastructurally: Neoplastic cells had branched cytoplasmic processes and were surrounded by an external lamina. Follow-up information was available 8 months to 10 years postexcision for 9 horses, for which surgical excision of the tumor was curative. The equine cutaneous schwannomas in this study had microscopic features like those of human schwannoma and had benign clinical behavior. Correct classification of equine cutaneous schwannoma will facilitate accurate prognosis and appropriate treatment.

A 9-year-old, female neutered Dalmatian was evaluated for acute onset of dyspnoea. Thoracocentesis on presentation yielded 1300 ml sanguineous fluid, while thoracic radiology and ultrasonography showed a mixed-echoic cavitary cranial mediastinal mass, sternal lymph node enlargement and pleural effusion. Surgical exploration of the thorax revealed a multi-lobulated red/brown cranial mediastinal mass and multiple similarly coloured ovoid nodules within several lung lobes. Histopathology revealed thymic branchial cysts with neoplastic transformation and examination of the lung was consistent with metastasis. Despite initially recovering well, acute sepsis and pyothorax resulted in cardiac arrest 8 days postoperatively. This is the first veterinary report of neoplastic transformation of a thymic branchial cyst with pulmonary metastasis.

Veterinary RecordVolume 167, Issue 10 p. 380-382 Short Communication Equine degenerative myeloencephalopathy in a horse in the UK R. J. Naylor BVetMed, MRCVS, Corresponding Author R. J. Naylor BVetMed, MRCVS rnaylor@rvc.ac.uk Royal Veterinary College, Hawkshead Lane, North Mymms, Hertfordshire, AL9 7TAE-mail for correspondence: rnaylor@rvc.ac.ukSearch for more papers by this authorS. L. Priestnall BVSc, BSc, PhD, S. L. Priestnall BVSc, BSc, PhD Royal Veterinary College, Hawkshead Lane, North Mymms, Hertfordshire, AL9 7TASearch for more papers by this authorA. C. Turk MA, VetMB, CertES(orth), A. C. Turk MA, VetMB, CertES(orth) Royal Veterinary College, Hawkshead Lane, North Mymms, Hertfordshire, AL9 7TASearch for more papers by this authorB. A. Summers BVSc, PhD, MRCVS, B. A. Summers BVSc, PhD, MRCVS Royal Veterinary College, Hawkshead Lane, North Mymms, Hertfordshire, AL9 7TASearch for more papers by this authorS. Schöniger Drmedvet, MS, S. Schöniger Drmedvet, MS Royal Veterinary College, Hawkshead Lane, North Mymms, Hertfordshire, AL9 7TASearch for more papers by this authorR. J. Piercy MA, VetMB, MS, PhD, R. J. Piercy MA, VetMB, MS, PhD Royal Veterinary College, Hawkshead Lane, North Mymms, Hertfordshire, AL9 7TASearch for more papers by this author R. J. Naylor BVetMed, MRCVS, Corresponding Author R. J. Naylor BVetMed, MRCVS rnaylor@rvc.ac.uk Royal Veterinary College, Hawkshead Lane, North Mymms, Hertfordshire, AL9 7TAE-mail for correspondence: rnaylor@rvc.ac.ukSearch for more papers by this authorS. L. Priestnall BVSc, BSc, PhD, S. L. Priestnall BVSc, BSc, PhD Royal Veterinary College, Hawkshead Lane, North Mymms, Hertfordshire, AL9 7TASearch for more papers by this authorA. C. Turk MA, VetMB, CertES(orth), A. C. Turk MA, VetMB, CertES(orth) Royal Veterinary College, Hawkshead Lane, North Mymms, Hertfordshire, AL9 7TASearch for more papers by this authorB. A. Summers BVSc, PhD, MRCVS, B. A. Summers BVSc, PhD, MRCVS Royal Veterinary College, Hawkshead Lane, North Mymms, Hertfordshire, AL9 7TASearch for more papers by this authorS. Schöniger Drmedvet, MS, S. Schöniger Drmedvet, MS Royal Veterinary College, Hawkshead Lane, North Mymms, Hertfordshire, AL9 7TASearch for more papers by this authorR. J. Piercy MA, VetMB, MS, PhD, R. J. Piercy MA, VetMB, MS, PhD Royal Veterinary College, Hawkshead Lane, North Mymms, Hertfordshire, AL9 7TASearch for more papers by this author First published: 04 September 2010 https://doi.org/10.1136/vr.c3818Read the full textAboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat No abstract is available for this article. Volume167, Issue10September 2010Pages 380-382 RelatedInformation

Congenital vascular tumors of the skin have been described in people and a few animals, but unlike infantile hemangiomas in children, spontaneous regression has not been described in animals. A 2-day-old male Belgian Blue cross calf was presented for multiple congenital cutaneous masses that were soft, alopecic, and hyperemic; the calf had no other apparent abnormalities. Two weeks later, one mass had regressed. Surgical excision of one of the remaining masses was performed; histopathologic and immunohistochemical findings were considered diagnostic for epithelioid hemangioma. Eight months following initial presentation, all the masses had regressed spontaneously. This constitutes the first account in the veterinary literature of spontaneous regression in a congenital vascular tumor.

An adult cat was presented with the history of 3 months' weight loss and more recent loss of balance and ataxia. An abdominal mass was palpable; results of neurologic examination suggested a brainstem disorder. The owners elected euthanasia. Postmortem findings included suppurative jejunal lymphadenitis and bilateral demyelination in the ventral pons with sparing of axons and neuronal soma. The location and character of the lesion mimicked those of human central pontine myelinolysis, an iatrogenic condition that may follow rapid correction of hyponatremia or develop spontaneously in patients with malnutrition or energy deprivation. In this cat, the poor nutritional state may have contributed to the development of this novel pontine lesion.