Telepathology, as a subset of teleconsulting, is pathology interpretation performed at a distance. Telepathology is not a new phenomenon, but since ~2015, significant advances in information technology and telecommunications coupled with the pandemic have led to unprecedented sophistication, accessibility, and use of telepathology in human and veterinary medicine. Furthermore, telepathology can connect veterinary practices to distant laboratories and provide support for underserved animals and communities. Through our scoping review, we provide an overview of how telepathology is being used in veterinary medicine, identify gaps in the literature, and highlight future areas of research and service development. We searched MEDLINE, CAB Abstracts, and the gray literature, and included all relevant literature. Despite the widespread use of digital microscopy in large veterinary diagnostic laboratories, we identified a paucity of literature describing the use of telepathology in veterinary medicine, with a significant gap in studies addressing the validation of whole-slide imaging for primary diagnosis. Underutilization of telepathology to support postmortem examinations conducted in the field was also identified, which indicates a potential area for service development. The use of telepathology is increasing in veterinary medicine, and pathologists must keep pace with the changing technology, ensure the validation of innovative technologies, and identify novel uses to advance the profession.

Caprine arthritis encephalitis virus (CAEV) is a monocyte/macrophage-tropic lentivirus that primarily infects goats resulting in a well-recognized set of chronic inflammatory syndromes focused on the joint synovium, tissues of the central nervous system, pulmonary interstitium and mammary gland. Clinically affected animals generally manifest with one or more of these classic CAEV-associated tissue lesions; however, CAEV-associated renal inflammation in goats has not been reported in the peer-reviewed literature. Here we describe six goats with chronic, multisystemic CAEV infections in conjunction with CAEV-associated renal lesions. One of the animals had CAEV antigen-associated thrombotic arteritis resulting in infarction of both the kidney and heart. These goats had microscopic evidence of inflammatory renal injury (interstitial nephritis) with detectable renal immunolabeling for CAEV antigen in three of six animals and amplifiable proviral sequences consistent with CAEV in all six animals. Cardiac lesions (vascular, myocardial or endocardial) were also identified in four of six animals. Within the viral promoter (U3) region, known transcription factor binding sites (TFBSs) were generally conserved, although one viral isolate had a duplication of the U3 A region encoding a second gamma-activated site (GAS). Despite the TFBS conservation, the isolates demonstrated a degree of phylogenetic diversity. At present, the clinical consequence of CAEV-associated renal injury is not clear.

Postmortem examination of deceased production animals with appropriate ancillary testing is fundamental to determining causes of morbidity and mortality. Reaching a definitive diagnosis is crucial to evidence-based herd management and treatment decisions that safeguard animal health and welfare, food safety, and human health. However, for a range of reasons, carcasses sometimes cannot be examined in a veterinary diagnostic laboratory. As a result, postmortem examinations of farmed animals, including cattle, are often performed on-farm by the referring veterinarian (rVet) with tissue samples submitted to a veterinary diagnostic laboratory for ancillary testing. For various reasons, field postmortems can be associated with lower diagnostic rates. We investigated real-time pathologist-assisted field postmortem examination (rtPAP) assistance to beef cattle rVets to gauge any improvement in attaining a final diagnosis. We found that rtPAPs improved the success of reaching a final diagnosis compared to unassisted field postmortem examinations. Both the participating bovine rVets and the pathologists saw benefits to the rtPAPs, with bovine rVets indicating that they would utilize this service in the future if available. Our proof-of-concept study demonstrated the positive role of rtPAPs in diagnosing beef cattle disease and speaks to the need for telepathology services supporting food animal rVets and producers.

Cardiac mesothelial hyperplasia forming pale plaque lesions on the epicardial surface is a common incidental finding in the hearts of aged humans. A similar phenomenon with a more papillary appearance has also been reported as an incidental finding in dogs and mice. These lesions are believed to occur in response to friction between the epicardium and overlying pericardium. We investigated this lesion in adult cattle, a phenomenon that has been associated with bovine leukemia virus infection and epicardial lymphoma. We examined 73 hearts from adult cattle, predominantly of dairy breeds: 53 from a rendering facility and 20 from a state diagnostic laboratory. Cardiac mesothelial hyperplasia was much more prevalent in cattle than in other reported species (97% of examined hearts). The most common distribution was overlying the great vessels in a dark red papillary pattern. Cardiac mesothelial hyperplasia was also variably observed on all 4 cardiac chambers and the pericardium. Occasionally these lesions took on a smooth plaque-like appearance resembling those observed in humans. The lesions varied from 0.25 cm ² to covering 90% of the epicardial surface. No association was observed between cardiac mesothelial hyperplasia and bovine leukemia virus infection or cardiac lymphoma. Cardiac mesothelial hyperplasia was a common incidental finding in bovine hearts that must be distinguished from neoplasia and acute or chronic inflammation.

OBJECTIVE: To describe the clinical findings, outcomes, and muscle histopathology in warmblood horses that developed severe rhabdomyolysis in the perianesthetic period despite remaining stable while under general anesthesia. ANIMALS: 7 warmblood horses, 6 geldings and 1 mare, with a median age of 9 years (range, 4 to 18 years) and median weight of 615 kg (range, 550 to 703 kg). Records from the Valberg Neuromuscular Diagnostic Laboratory and Michigan State University were reviewed (2016 to 2023) to identify warmbloods with postanesthetic myopathy (PAM). CLINICAL PRESENTATION: Warmblood horses with no history of myopathy developed PAM after remaining stable while under general anesthesia. Five of 7 horses were in regular work prior to anesthesia, and activity level was unknown in 2 horses. Time to standing in recovery was prolonged, 3 horses were euthanized due to persistent recumbency, and rhabdomyolysis recurred in 4 horses 5 to 11 days after anesthesia, with 1 surviving. Horses had muscle stiffness, pain, and sweating and struggled to remain standing. As PAM developed, serum creatine kinase activity and lactate concentrations (12 ± 7 mmol/L; n = 5) were markedly increased. RESULTS: At necropsy, histopathology revealed complete glycogen depletion (5 of 7), acute myodegeneration (6 of 7), and chronic active myodegeneration of representative skeletal muscle samples. A semimembranosus biopsy obtained 14 days after anesthesia from the survivor had rare glycogen-depleted fibers. CLINICAL RELEVANCE: Warmblood horses are susceptible to fatal PAM characterized by acute myodegeneration, lactic acidosis, and muscle glycogen depletion that occurs up to 11 days after anesthesia. In horses with delayed recovery after anesthesia, monitoring for 2 weeks after anesthesia, including assessment of serum creatine kinase activity and blood lactate, could potentially improve outcomes.

Feline infectious peritonitis (FIP), caused by a mutated biotype of feline coronavirus (FCoV; Coronaviridae , Alphacoronavirus ), is a significant disease of felids. We investigated perirenal hemorrhage, an unreported lesion in FIP, through a retrospective analysis of 51 immunohistochemistry-confirmed FIP cases submitted to the Diagnostic Services Unit (DSU; University of Calgary, Calgary, Alberta, Canada) between 2010 June 30 and 2024 June 30. Five cats had perirenal hemorrhage in the right retroperitoneal space; 4 had concurrent subcapsular renal hemorrhage; and 1 had sublumbar muscle hemorrhage and hemoabdomen. One case had additional hemorrhages in the brain and cervical spinal cord. Concurrent gross lesions typical of FIP included pyogranulomatous inflammation in various organs and protein-rich cavitary effusions. Histologic lesions typical of FIP (vasculitis and pyogranulomatous inflammation) were present in the kidneys and retroperitoneal fat of 4 cases, and in 3 cases, FCoV antigen was demonstrated in the regions of hemorrhage. The exact mechanism of this hemorrhage is unknown, but we speculate that vasculitis caused by FIP is the cause. Despite the relatively low prevalence of perirenal hemorrhage in this cohort, this lesion represents a unique, previously unreported manifestation of FIP that clinicians and pathologists should be aware of and consider in the differential diagnosis for fluid accumulation or space-occupying lesions in the retroperitoneum of cats.