Pathologic characterization of canine multiple system degeneration in the Ibizan hound.

Canine multiple system degeneration (CMSD) is a progressive hereditary neurodegenerative disorder commonly characterized by neuronal degeneration and loss in the cerebellum, olivary nuclei, substantia nigra, and caudate nuclei. In this article, we describe 3 cases of CMSD in Ibizan hounds. All patients exhibited marked cerebellar ataxia and had cerebellar atrophy on magnetic resonance imaging. At necropsy, all cases showed varying degrees of cerebellar atrophy, and 2 cases had gross cavitation of the caudate nuclei. Histologic findings included severe degeneration and loss of all layers of the cerebellum and neuronal loss and degeneration within the olivary nuclei, substantia nigra, and caudate nuclei. Pedigree analysis indicated an autosomal recessive mode of inheritance, but the causative gene in this breed is yet to be identified. CMSD resembles human multiple system atrophy and warrants further investigation.

Mitotic Figures-Normal, Atypical, and Imposters: A Guide to Identification.

Counting mitotic figures (MF) in hematoxylin and eosin-stained histologic sections is an integral part of the diagnostic pathologist's tumor evaluation. The mitotic count (MC) is used alone or as part of a grading scheme for assessment of prognosis and clinical decisions. Determining MCs is subjective, somewhat laborious, and has interobserver variation. Proposals for standardizing this parameter in the veterinary field are limited to terminology (use of the term MC) and area (MC is counted in an area measuring 2.37 mm2). Digital imaging techniques are now commonplace and widely used among veterinary pathologists, and field of view area can be easily calculated with digital imaging software. In addition to standardizing the methods of counting MF, the morphologic characteristics of MF and distinguishing atypical mitotic figures (AMF) versus mitotic-like figures (MLF) need to be defined. This article provides morphologic criteria for MF identification and for distinguishing normal phases of MF from AMF and MLF. Pertinent features of digital microscopy and application of computational pathology (CPATH) methods are discussed. Correct identification of MF will improve MC consistency, reproducibility, and accuracy obtained from manual (glass slide or whole-slide imaging) and CPATH approaches.

International Guidelines for Veterinary Tumor Pathology: A Call to Action.

Standardization of tumor assessment lays the foundation for validation of grading systems, permits reproducibility of oncologic studies among investigators, and increases confidence in the significance of study results. Currently, there is minimal methodological standardization for assessing tumors in veterinary medicine, with few attempts to validate published protocols and grading schemes. The current article attempts to address these shortcomings by providing standard guidelines for tumor assessment parameters and protocols for evaluating specific tumor types. More detailed information is available in the Supplemental Files, the intention of which is 2-fold: publication as part of this commentary, but more importantly, these will be available as "living documents" on a website (www.vetcancerprotocols.org), which will be updated as new information is presented in the peer-reviewed literature. Our hope is that veterinary pathologists will agree that this initiative is needed, and will contribute to and utilize this information for routine diagnostic work and oncologic studies. Journal editors and reviewers can utilize checklists to ensure publications include sufficient detail and standardized methods of tumor assessment. To maintain the relevance of the guidelines and protocols, it is critical that the information is periodically updated and revised as new studies are published and validated with the intent of providing a repository of this information. Our hope is that this initiative (a continuation of efforts published in this journal in 2011) will facilitate collaboration and reproducibility between pathologists and institutions, increase case numbers, and strengthen clinical research findings, thus ensuring continued progress in veterinary oncologic pathology and improving patient care.

Anaplastic Large T-Cell Lymphoma in the Intestine of Dogs.

Anaplastic large T-cell lymphoma (ALTCL) is a rare subtype of non-Hodgkin T-cell lymphoma that occasionally occurs in the gastrointestinal tract of humans. Enteropathy-associated T-cell lymphoma (EATL) type 1 is the most common type of intestinal lymphoma in dogs, and ALTCL has not previously been reported in the intestinal tract of dogs. Thirteen dogs with intestinal masses diagnosed as intestinal lymphoma with anaplastic morphology were reviewed. Clinical data, including treatment protocols, were available for 11 cases. Immunohistochemistry for CD3, CD20, and CD30 was performed for all cases in addition to PCR for Antigen Receptor Rearrangements (PARR) for assessment of clonality. Eight (62%) of the cases presented with intestinal perforation, and all cases had 1 or more masses arising from the small intestine. Histologically, all cases were characterized by transmural infiltrates of large, CD3-positive and frequently CD30-positive cells. Neoplastic T cells had marked anisocytosis and anisokaryosis, prominent nucleoli, and occasionally indented to reniform nuclei. There was abundant necrosis and inflammation with occasional vascular invasion within neoplastic masses. All cases had a monoclonal T-cell receptor γ gene rearrangement. The median survival time was 5 days, with 1 dog surviving 2 years after the initial diagnosis. ALTCL can occur as an aggressive transmural lymphoma in the gastrointestinal tract of dogs and commonly causes intestinal perforation. ALTCL can be differentiated from EATL type 1 and might have implications for accurate prognostication and selection of therapeutic options in the future.

The Pathology of Wobbly Hedgehog Syndrome.

Wobbly hedgehog syndrome (WHS) is a leading cause of neurologic disease in African pygmy hedgehogs (APHs; Atelerix albiventris). This study describes the signalment, clinical signs, gross, microscopic, and ultrastructural lesions of WHS in a cohort of 12 pet APHs. Microscopically, lesions consisted of status spongiosus of the white matter, typically bilateral and symmetrical, with myelin degeneration and loss that was accompanied by neuronal/axonal degeneration plus reactive microgliosis and mild, focal astrocytosis and astrogliosis. Lesions were most severe in the cerebellum and medulla oblongata, as well as cervical and thoracic spinal cord. Less affected areas were the corona radiata, corpus callosum, corpus striatum, internal capsule, and the mesencephalon. Ultrastructurally, the lesions consisted of splitting of the myelin sheath at the intraperiod line with subsequent focal expansion, resulting in status spongiosus, disruption, dilatation, rhexis, and phagocytosis. Based on these results, WHS is best described as a "spongy myelinopathy" with widespread central nervous system involvement.

Genomic analysis across 53 canine cancer types reveals novel mutations and high clinical actionability potential.

A genomic understanding of the oncogenic processes and individual variability of human cancer has steadily fueled improvement in patient outcomes over the past 20 years. Mutations within tumour tissues are routinely assessed through clinical genomic diagnostic assays by academic and commercial laboratories to facilitate diagnosis, prognosis and effective treatment stratification. The application of genomics has unveiled a wealth of mutation-based biomarkers in canine cancers, suggesting that the transformative principles that have revolutionized human cancer medicine can be brought to bear in veterinary oncology. To advance clinical genomics and genomics-guided medicine in canine oncology, we have developed and validated a canine cancer next-generation sequencing gene panel for the identification of multiple mutation types in clinical specimens. With this panel, we examined the genomic landscapes of 828 tumours from 813 dogs, spanning 53 cancer types. We identified 7856 alterations, encompassing copy number variants, single nucleotide variants, indels and internal tandem duplications. Additionally, we evaluated the clinical utility of these alterations by incorporating a biomarker framework from comprehensive curation of primary canine literature and inferences from human cancer genomic biomarker literature and clinical diagnostics. Remarkably, nearly 90% of the cases exhibited mutations with diagnostic, prognostic or therapeutic implications. Our work represents a thorough assessment of genomic landscapes in a large cohort of canine cancers, the first of its kind for its comprehensive inclusion of multiple mutation types and structured annotation of biomarkers, demonstrating the clinical potential of leveraging mutation-based biomarkers in veterinary oncology.

Genomic tumor analysis provides clinical guidance for the management of diagnostically challenging cancers in dogs.

OBJECTIVE: To evaluate the diagnostic, prognostic, and therapeutic utility of a cancer genomic diagnostic assay (SearchLight DNA; Vidium Animal Health) for diagnostically ambiguous cancer cases. ANIMALS: 69 privately owned dogs with ambiguous cancer diagnoses and for which the genomic assay was performed. PROCEDURES: Genomic assay reports generated between September 28, 2020, and July 31, 2022, for dogs with malignancy or suspected malignancy were reviewed to determine the assay's clinical utility defined as providing diagnostic clarity, prognostic information, and/or therapeutic options. RESULTS: Genomic analysis provided diagnostic clarity in 37 of 69 cases (54%; group 1) and therapeutic and/or prognostic information in 22 of the remaining 32 cases (69%; group 2) for which the diagnosis remained elusive. Overall, the genomic assay was clinically useful in 86% (59/69) of cases. CLINICAL RELEVANCE: To our knowledge, this was the first study to evaluate the multifaceted clinical utility of a single cancer genomic test in veterinary medicine. Study findings supported the use of tumor genomic testing for dogs with cancer, particularly those that are diagnostically ambiguous and therefore inherently challenging to manage. This evidence-driven genomic assay provided diagnostic guidance, prognostic support, and therapeutic options for most patients with an unclear cancer diagnosis that would otherwise have an unsubstantiated clinical plan. Furthermore, 38% (26/69) of samples were easily obtained aspirates. Sample factors (sample type, percentage of tumor cells, and number of mutations) did not influence diagnostic yield. Our study demonstrated the value of genomic testing for the management of canine cancer.

Standing in the canine precision medicine knowledge gap: Improving annotation of canine cancer genomic biomarkers through systematic comparative analysis of human cancer mutations in COSMIC.

The accrual of cancer mutation data and related functional and clinical associations have revolutionised human oncology, enabling the advancement of precision medicine and biomarker-guided clinical management. The catalogue of cancer mutations is also growing in canine cancers. However, without direct high-powered functional data in dogs, it remains challenging to interpret and utilise them in research and clinical settings. It is well-recognised that canine and human cancers share genetic, molecular and phenotypic similarities. Therefore, leveraging the massive wealth of human mutation data may help advance canine oncology. Here, we present a structured analysis of sequence conservation and conversion of human mutations to the canine genome through a 'caninisation' process. We applied this analysis to COSMIC, the Catalogue of Somatic Mutations in Cancer, the most prominent human cancer mutation database. For the project's initial phase, we focused on the subset of the COSMIC data corresponding to Cancer Gene Census (CGC) genes. A total of 670 canine orthologs were found for 721 CGC genes. In these genes, 365 K unique mutations across 160 tumour types were converted successfully to canine coordinates. We identified shared putative cancer-driving mutations, including pathogenic and hotspot mutations and mutations bearing similar biomarker associations with diagnostic, prognostic and therapeutic utility. Thus, this structured caninisation of human cancer mutations facilitates the interpretation and annotation of canine mutations and helps bridge the knowledge gap to enable canine precision medicine.

Multiple eccrine poromas in the paw of a dog.

A 5-year-old, spayed female boxer dog presented to the referring veterinarian with a year-long history of swelling, ulceration and pain in the pawpad of the fourth digit of the right forelimb. Histologically, the pawpad was expanded by a mass composed of small polygonal cells forming broad bands and trabeculae within the lower epidermis that often infiltrated and replaced the overlying keratinocytes and that extended into the dermis. Lobules of eccrine glands within the deep dermis occasionally had one or more eccrine ducts that were lined by neoplastic ductal epithelial cells that formed papillary projections lined by one to two layers of neoplastic cells. Approximately 1 month after amputation of the fourth digit pad, several smaller nodular masses developed in multiple digital pads and the metacarpal pad of the same paw. All of the neoplasms were histologically identical to eccrine poroma (juxtaepidermal acrospiroma), a common benign neoplasm in humans that originates from the acrosyringium and upper dermal duct of eccrine glands. To the authors' knowledge this is the first report documenting an eccrine poroma in a dog.

Histopathologic and Molecular Characterization of Sarcocystis calchasi Encephalitis in White-winged Doves ( Zenaida asiatica ) and Eurasian Collared Doves ( Streptopelia decaocto ), East-central Texas, USA, 2010-13.

Sarcocystis calchasi is a recently described apicomplexan parasite that causes encephalitis in avian hosts. We diagnosed one White-winged Dove ( Zenaida asiatica ) and two Eurasian Collared Doves ( Streptopelia decaocto ) in Texas, US, with a history of neurologic signs with protozoal encephalitis. On histologic examination, all three doves had moderate to severe meningoencephalitis characterized by large numbers of plasma cells, lymphocytes, and macrophages with gliosis and astrocytosis. Brain sections from two doves also contained numerous Mott cells. Protozoal schizonts with rosettes or clusters of individual merozoites consistent with Sarcocystis spp. were seen within areas of inflammation. Sarcocysts were also identified in the skeletal muscle of one dove. The PCR and sequencing of brain and skeletal muscle from two doves revealed 99% identity with S. calchasi. The presence of S. calchasi in fatal cases of encephalitis in doves in Texas suggests that the geographic and host ranges of S. calchasi are broader than previously reported.