This study investigates the molecular and immune characteristics of equine ocular squamous cell carcinoma (eoSCC). Immunohistochemistry (IHC) and next-generation sequencing (NGS) were used to detect protein expression and TP53 mutations, respectively. T lymphocytes (CD3+), regulatory T cells (FoxP3+), B lymphocytes (CD20+), and macrophages (IBA-1+) were quantified. A total of 29 cases of eoSCC were evaluated, consisting of 3/29 carcinomas in situ (CISs) and 26/29 squamous cell carcinomas (SCCs). p53 positivity by IHC was detected in 19/29 cases while by NGS, 21 TP53 mutations were found in 13/29 cases (44.83%), of which 18/21 were C > T base substitutions, typical of ultraviolet (UV)-induced DNA damage. In tumors with TP53 mutations, IBA-1⁺ macrophages were significantly increased (p = 0.001) and CD3⁺ T lymphocytes were also more abundant (p = 0.028) than in wild type TP53 cases, whereas CD20⁺ B lymphocytes and FoxP3⁺ regulatory T lymphocytes showed no significant differences. Equus caballus papillomavirus type 2 positivity was detected in 6/29 cases (20.69%) via in situ hybridization (ISH), but viral presence did not impact immune cell infiltration. Ki67 scores were higher in SCCs/CISs withTP53 mutations, but the difference was not statistically significant. Overall, TP53 mutations appear to contribute to eoSCC development, potentially as a consequence of UV-light exposure, and to influence immune cell infiltration.

Nasal hamartoma (NH) is a rare nonneoplastic excessive growth of native tissue of the nasal cavity. Four histological subtypes are described in cats and dogs: mesenchymal nasal hamartoma (MNH), epithelial hamartoma, mixed tissue (chondro-osseous and respiratory epithelial adenomatoid hamartoma/COREAH), and nasal vascular hamartoma. This descriptive, retrospective study aims to describe the computed tomographic (CT) features of feline NHs. Fourteen cats were included (six MNH, six COREAH, one epithelial, and one vascular). Twelve MNH and COREAH were soft-tissue and mineral-attenuating locally invasive nasal masses with expansile behavior (nine unilateral and three bilateral). The nasal turbinate architecture was replaced by exuberant/disorganized mineral densities arranged in a "cerebroid pattern" in all cases. Contrast enhancement was moderate in 75% of cats. Commonly, the mass extended into the rostral nasopharynx, contralateral choana/nasal cavity, and nostrils, more rarely into the orbital cavity and/or facial soft tissue. Focal osteolysis/atrophy of the paranasal bones was common (10/12 cases). The epithelial and vascular hamartomas were soft tissue-attenuating unilateral masses without mineral components. Contrast enhancement was marked in the vascular hamartoma. NHs are relatively rare, tumor-like growths in cats that mainly contain mesenchymal elements. Common CT features include expansile nasal lesions that are locally invasive, characterized by a mineral "cerebroid pattern." Despite the low incidence, it is crucial to be aware of their presence and include them in the differential diagnosis of feline nasal masses.

Feline nasal carcinomas are rare but clinically aggressive neoplasms. This study characterizes their histopathological features and evaluates HER2, p53, Ki-67, and PCNA expression using immunohistochemistry and digital image analysis, aiming to provide a comprehensive biological characterization with potential prognostic and therapeutic implications. Tumors were classified into adenocarcinomas (AC) and non-adenocarcinomas (non-AC). Among the 23 cases examined, adenocarcinoma was the most common subtype (17 cases). HER2 was scored as 3+ in 7 cases, 2+ in 8 cases, 1+ in 5 cases, and 3 cases were scored 0. A statistically significant association was found between histological type and HER2 expression (Fisher’s exact test, p = 0.02), with a higher prevalence of HER2 positivity in adenocarcinomas. Evaluation of p53 expression according to histological grouping showed a trend toward significance (p = 0.0593), with p53 positivity observed exclusively in non-AC. The Ki-67 index had a median of 4.4 (min 0.5, max 21.06), and the PCNA index had a median of 82.26 (min 19.55, max 100). No significant associations were identified between the Ki-67 labeling index and HER2 expression, histotype, and the inflammatory infiltrate. Finally, Pearson correlation analysis revealed no significant correlation between Ki-67 and PCNA indices (p = 0.32). The overexpression of HER2 lays the groundwork for the possible use of anti-HER2 targeted drugs in this tumor type, particularly in adenocarcinomas. These findings provide baseline immunohistochemical data for feline nasal carcinomas and highlight HER2 as a relevant biomarker for future diagnostic and therapeutic research.

The tumor-immune microenvironment (TIME) plays a pivotal role in cancer progression, yet its characterization in veterinary oncology remains limited. Eighty-five soft tissue sarcomas (STSs), comprising fibrosarcomas, leiomyosarcomas, liposarcomas, myxosarcomas, and perivascular wall tumors (PWTs), were immunohistochemically assessed for IBA-1 (total tumor-associated macrophages) and CD204 (M2-like macrophages) expression, scored by image analysis, and correlated with histological parameters. IBA-1 was higher in grade 3 STSs compared with grade 1 (W = 3.40, P = .043) and in PWTs compared with myxosarcomas (W = 6.037, P < .001). CD204 was lower in PWTs compared with fibrosarcomas (W = 5.152, P = .003), leiomyosarcomas (W = 4.394, P = .016), and myxosarcomas (W = 4.812, P = .006). Stratifying by STS type, IBA-1 was higher in grade 2 myxosarcomas compared with grade 1 (Mann U = 4, P = .018). IBA-1 and CD204 were higher in myxosarcomas with necrosis compared with those without (Mann U = 5, P = .026, and Mann U = 0, P = .001, respectively). In PWTs, the mitotic count was higher in cases with higher IBA-1 (Spearman's rho = 0.438, P = .041) and cases with lower CD204 (Spearman's rho = -0.459, P = .035). Considering all STSs, IBA-1 correlated with total tumor-infiltrating lymphocytes (TILs), T-cells, and regulatory T-cells (Tregs). In fibrosarcomas, IBA-1 and CD204 directly correlated with total TILs, T-cells, and Tregs. In myxosarcomas, CD204 correlated with Tregs. In leiomyosarcomas, IBA-1 scores correlated with Tregs and CD204 with T-cells and Tregs. In PWTs, B-cells correlated with IBA-1 and inversely correlated with CD204. These findings suggest the presence of a TIME favoring anti-tumor immunity in PWTs and a pro-tumoral TIME in myxosarcomas, reinforcing the concept that canine STS histotypes elicit distinct immune responses.

BACKGROUND:Splenic hemangiosarcoma (SHSA) is an aggressive neoplasm of dogs characterized by high metastatic rate and short survival time. Although staging and treatment are well established prognostic factors, the implication of specific metastatic sites remains unclear. HYPOTHESIS/OBJECTIVES:Describe the frequency and distribution of metastatic site at diagnosis in dogs with SHSA and evaluate the potential prognostic role of different metastatic locations. ANIMALS:Sixty-six dogs with histologically confirmed SHSA. METHODS:Retrospective, multicenter, descriptive study of dogs with SHSA treated by splenectomy. Data collected included demographics, clinical stage, and site of metastasis at diagnosis and at death, staging procedures, histopathology results, treatment protocols, and outcome. Survival analysis was conducted using Kaplan-Meier and Cox proportional hazards models. RESULTS:At diagnosis, three dogs were stage I (5%), 35 stage II (53%), and 28 stage III (42%). Overall median tumor-specific survival (TSS) was 132 days. Stage III disease and hepatic metastases were associated with significantly decreased survival (P < .001). Dogs with liver metastasis that received anthracycline-based chemotherapy had longer survival compared with dogs that received metronomic therapy (255 vs 65 days, P = .02). Muscular and pulmonary metastases did not correlate with worse outcomes. CONCLUSIONS AND CLINICAL IMPORTANCE:Stage and treatment were confirmed as prognostic factors, with patients in stage III and patients having received surgery alone having a worse prognosis. Although current staging classifies all metastatic disease as stage III, metastatic site may have variable impact on survival and should be considered when devising treatment strategy.

Equine penile tumors are common in horses and are often related to infection with equine papillomavirus type 2 (EcPV2). This study investigated the immune cell infiltrate (ICI) of these tumors in horses, focusing on the role of EcPV2. Using multiplex immunohistochemistry (mIHC) for CD3, CD20, and IBA-1 and immunohistochemistry (IHC) for FoxP3, 27 horses with papillomas (5/27), in situ carcinomas (CISs) (3/27), and squamous cell carcinomas (SCCs) (19/27) were evaluated. Eighteen cases tested positive for EcPV2 by either or both in situ hybridization (ISH) and polymerase chain reaction (PCR) (18/27 by PCR, of which 16 were ISH+). The ICIs were more abundant in EcPV2-positive tumors, although differences were not statistically significant. The number of FoxP3+ regulatory T-cells was significantly higher in EcPV2+ tumors, both in intraepithelial and stromal compartments. There were higher IBA-1+ macrophage densities in SCCs than in papillomas or CISs. p53 IHC was performed, and non-basal positivity was associated with malignancy. The TP53 mutational analysis with next-generation sequencing revealed that 13/21 cases had a wild-type TP53, while TP53 variants were detected in 4/21 cases. The ICIs did not vary according to TP53 status. Tumor proliferation was also assessed with Ki67, which indicated progressively higher proliferation from benign to malignant tumors. In conclusion, although the number and distribution of B-cells, T-cells, and macrophages did not vary according to EcPV2 status, FoxP3 regulatory T-cells were observed in significantly higher numbers in EcPV2+ neoplasms, indicating a different immune landscape compared to EcPV2-negative tumors.

Canine anal sac adenocarcinoma (ASAC) is an aggressive malignancy with high metastatic potential. Histologic and proliferation parameters such as mitotic count and Ki67 scores have limited prognostic value according to the published literature. Using pathologist-supervised digital image analysis methods with the image analysis software QuPath, we analyzed 58 cases of ASAC to evaluate mitotic count (MC) and Ki67 indices, explore relationships between different Ki67 indices [semi-automatic Ki67 digital hotspot score (Ki67-saHDS), Ki67 global digital score (Ki67-GDS), and fully automatic Ki67 digital hotspot score (Ki67-faHDS)] and MC, and to verify which method carries the most significant prognostic value. The MC did not impact median tumor-related survival (TRS) time. Although high correlation coefficients were observed between the 3 Ki67 scores, Ki67-GDS had more prognostic relevance than hotspot-based scores (Ki67-saHDS and Ki67-faHDS). Dogs with Ki67-GDS ≥ 26 had significantly shorter survival times (175, days 95%, confidence interval (95% CI) = 123-540) compared to dogs with Ki67-GDS< 26 (median survival time (MST) 650 days, 95% CI = 503->1579). No association was observed between TRS and Ki67-faHDS or Ki67-saHDS. On multivariate analysis, anisokaryosis and Ki67-GDS, but not tumor size, lymphovascular invasion, or MC, were independent prognostic markers for survival. These results demonstrate the advantage of Ki67 GDS over hotspot-based scores; however, these data need to be validated in a larger cohort of cases before clinical implementation.

Feline calicivirus (FCV) is widespread in multi-cat environments and typically causes acute upper respiratory tract disease (URTD). FCV also causes outbreaks of virulent systemic disease (VSD), mainly in adults, with multiple organ involvement. In this study, an FCV-VSD infection was described in a less-one-month-old Maine Coon kitten originating from a cattery where an outbreak of FCV-URTD had previously been reported. After spontaneous death, post-mortem examination as well as histopathological, immunohistochemical, bacteriological and virological investigations were carried out. Pathological findings were consistent with severe pneumonia and cutaneous oedema of the footpads. No concomitant bacterial infection was detected. FCV RNA was detected in several organs and the highest amount of viral RNA was observed in the lung sample, in which the presence of the FCV antigen was confirmed by immunohistochemistry. With the same immunohistochemical technique, the IBA-1 antibody detected sparse alveolar macrophages, the main viral target cell and pulmonary replication site. The nucleotide sequences of the viral ORF2 gene amplified from all positive tissues were identical with each other and phylogeny confirms that highly virulent FCV strains are not distinguishable from FCV-URTD phenotypes. Our findings reinforce the hypothesis that VSD outbreaks can occur even in small populations, due to the high genetic variability of FCV.

Mitotic count (MC) is a well-established prognostic factor in many canine malignancies. While standardisation efforts have improved inter-pathologist agreement regarding the morphology of mitotic figures and the size of the counting area, the selection of the tumour region for MC assessment remains to be standardised. This study aimed to evaluate the spatial distribution of the most proliferative areas in selected canine tumour types, using Ki67 immunohistochemistry, to identify optimal candidate regions for MC assessment. Tumour types analysed included melanomas, cutaneous mast cell tumours (cMCT), canine mammary carcinomas (CMC) and soft tissue sarcomas (STS). Using image analysis, Ki67 density maps were generated from digital slides and classified according to their distribution pattern (focal/multifocal or diffuse) and location within the tumour (central, peripheral or scattered). A total of 202 cases were included: 43 melanomas, 30 cMCTs, 42 CMCs and 87 cSTSs. The vast majority of tumours (92.6%) exhibited a multifocal hotspot distribution. Peripheral hotspot localisation was predominant in 55% of cases, particularly in cMCTs (73.3%) and melanomas (76.7%). In contrast, cSTSs more frequently showed a scattered hotspot pattern (60.9%) (χ2 = 41.9; p < 0.001). CMCs had a higher proportion of centrally located hotspots (16.7%). These findings suggest that pathologists should focus on peripheral tumour regions when assessing MC in cMCTs and melanomas. Both central and peripheral regions should be considered in CMCs, while a more extensive, comprehensive evaluation may be required in STSs. The observed association between tumour histotype and proliferation pattern likely reflects inherent biological differences among the tumour types studied.

Recently, human epidermal growth factor receptor 2 (HER2) has emerged as a therapeutic target of interest for non-small-cell lung cancer in humans. The role of HER2 in canine pulmonary adenocarcinomas is poorly documented. To address this gap, this study employed three methodologies: immunohistochemistry (IHC), fluorescence in situ hybridization (FISH), and next-generation sequencing (NGS) to investigate the protein expression, gene amplification, and mutation of HER2 in 19 canine primary pulmonary adenocarcinomas. By IHC, 3 out of 19 cases were overexpressed 3+, 6 were 2+, and 10 were negative. With FISH, 2 cases were amplified (12.5%), 3 were inadequate for the analyses, and the others were non-amplified. With NGS, seven cases were inadequate. All other cases were wild-type, except for one IHC 3+ case, which was amplified with FISH and with a specific mutation already described in human pulmonary adenocarcinoma, V659E. This mutation is probably sensitive to tyrosine kinase inhibitory drugs. These results are similar to those in human medicine and to the few data in the literature on canine lung carcinomas; the presence of 12.5% of amplified cases in dogs lays the foundation for future targeted drugs against HER2 alterations.

Performing a mitosis count (MC) is the diagnostic task of histologically grading canine Soft Tissue Sarcoma (cSTS). However, mitosis count is subject to inter- and intra-observer variability. Deep learning models can offer a standardisation in the process of MC used to histologically grade canine Soft Tissue Sarcomas. Subsequently, the focus of this study was mitosis detection in canine Perivascular Wall Tumours (cPWTs). Generating mitosis annotations is a long and arduous process open to inter-observer variability. Therefore, by keeping pathologists in the loop, a two-step annotation process was performed where a pre-trained Faster R-CNN model was trained on initial annotations provided by veterinary pathologists. The pathologists reviewed the output false positive mitosis candidates and determined whether these were overlooked candidates, thus updating the dataset. Faster R-CNN was then trained on this updated dataset. An optimal decision threshold was applied to maximise the F1-score predetermined using the validation set and produced our best F1-score of 0.75, which is competitive with the state of the art in the canine mitosis domain.

Canine liposarcoma is an uncommon tumor that shares morphological similarities with its human counterpart. In dogs, the genetic features of this tumor are unknown and, based on immunohistochemical studies, amplification of the gene MDM2 and the mutation of TP53 are suspected. In this study 51 cases of primary liposarcomas were immunohistochemically stained for MDM2 and p53 and subjected to fluorescent in situ hybridization and next-generation sequencing to detect MDM2 amplification and TP53 mutations, respectively. MDM2 and p53 were expressed in 21 and 6 cases, respectively. MDM2 amplification and TP53 mutations were identified in 10 and 15 cases, respectively. Statistical analysis revealed an association of the myxoid subtype and the mitotic count with p53 expression and TP53 mutation. No association was found between MDM2 amplification and MDM2 expression or tumor subtype. These results suggest that despite morphological similarities, canine liposarcoma differs from its human counterpart, for which MDM2 amplification is diagnostic for well differentiated and de-differentiated variants, and TP53 mutations are more common in pleomorphic liposarcoma rather than the myxoid one as occur in our cases. Furthermore, canine myxoid liposarcoma likely represents a distinct disease rather than a mere morphological variant.

Canine splenic hemangiosarcoma has a high metastatic rate and short survival time. Currently, the main prognostic parameters are tumor stage and therapy, while data on histologic parameters, such as grade and Ki-67 expression, are scarce. The aims of this study were to compare two methods of assessment of Ki-67, verify their prognostic impact, and define a threshold value based on survival. Thirty-one cases of histologically diagnosed canine splenic hemangiosarcoma, which were treated with splenectomy and had full staging and follow-up information, were collected. Three were stage I, 17 stage II, and 11 stage III. The mean mitotic count (MC) was 23.9 (standard deviation [SD]: 22.1) and the median was 15 (range, 1-93). Immunohistochemistry for Ki-67 was performed, the Ki-67 labeling index (Ki-67LI) was assessed as a percentage of positive neoplastic nuclei per ≥500 cell, and the Ki-67 count (KI-67C) was defined as the average number of positive nuclei using a 1 cm2 optical grid performed in 5, 40× fields. The mean Ki-67LI and Ki-67C were 56.4% (SD: 38.7) and 27.2 (SD: 12.9) and medians were 51% (range, 8.2-55.2) and 26 (range, 5.5-148), respectively. Using a cut-off of 56% and 9, respectively, Kaplan-Meier survival curves showed an association of overall survival with Ki-67LI and MC. In addition to clinical stage, Ki-67LI maintained its prognostic value on multivariate analysis, supporting the role of Ki-67LI as an independent prognostic parameter. Based on these results, we propose a diagnostically applicable cut-off value of 56% for Ki-67LI as a prognostic parameter for canine splenic hemangiosarcoma.

This study explores the efficacy of diffusion probabilistic models for generating synthetic histopathological images, specifically canine Perivascular Wall Tumours (cPWT), to supplement limited datasets for deep learning applications in digital pathology. This research evaluates an open-source medical domain-focused diffusion model called Medfusion, where the model was trained on a small (1,000 patches) and a large dataset (17,000 patches) of cPWT images to compare performance on the different sized datasets. A Receiver Operating Characteristic (ROC) study was implemented to investigate the ability of six veterinary medical professionals and pathologists to discern between generated and real cPWT patch images. The participants engaged in two separate rounds, where each round corresponded to models that had been trained on the two different sized datasets. The ROC study revealed mean average Area Under the Curve (AUC) values close to 0.5 for both rounds. The results from this study suggests that diffusion models can create histopathological patch images that are convincingly realistic where our participants often struggled to reliably differentiate between generated and real images. This underscores the potential of these models as a valuable tool for augmenting digital pathology datasets.

Canine anal sac gland adenocarcinomas (ASACs) are locally aggressive and highly metastatic to regional lymph nodes. Tumor-infiltrating lymphocytes (TILs) and tumor-associated macrophages (TAMs) can be effective prognostic and predictive markers in numerous human neoplasms and are increasingly investigated in dogs. The aim of this study was to characterize immune cells in canine ASACs and their relationship with tumor size, histologic metastatic status, and tumor clinical stage. Thirty ASACs with known tumor size, metastatic status, and clinical stage were immunolabeled for Iba1 (macrophages), CD20 (B cells), CD3 (T cells), and Foxp3 (regulatory T cells). With image analysis, two areas of 1 mm2 were analyzed for each case at the tumor core (TC) and invasive margin (IM) and immune cells were counted. Eighteen patients had metastasis at the time of diagnosis, of which fifteen were nodal only, and three were both distant and nodal. The median tumor size was 32.5 mm (range 11-70). The clinical stage was I in five cases, II in seven cases, III in fifteen cases, and IV in three cases. T cells and macrophages were the most abundant immune cells in all tumors. Tumor size did not influence the number or type of infiltrating immune cells. By contrast, significantly higher numbers of TC T lymphocytes were found in patients without metastasis, while significantly higher numbers of TC macrophages were found in dogs with metastasis. Immune cell infiltrate did not differ according to clinical stage. The results indicate that the tumor immune microenvironment, specifically TILs and TAMs, contribute to tumor behavior and may influence metastatic potential; in particular, high CD3 infiltration may prevent tumor progression, while increased macrophage infiltration could promote it.

Soft tissue sarcomas (STSs) are conventionally viewed as poorly immunogenic tumors; however, some human STSs have recently been reported to elicit an immune response, thus representing potential candidates for immunotherapy. Data regarding immune cell infiltrates in canine STSs are limited and reported without tumor-type stratification. The aim of this study was to retrospectively assess tumor-infiltrating lymphocytes (TILs) in canine STSs of 5 different histotypes. Eighty-seven canine STSs were collected: 22 perivascular wall tumors (PWTs), 19 liposarcomas, 17 fibrosarcomas, 16 myxosarcomas, and 13 leiomyosarcomas. The tumors were graded and immunolabeled for CD3, CD20, and FoxP3, and slides were scanned. T-cell, B-cell, Treg, and total TIL densities were quantified with QuPath software and expressed as cells/mm2. The B/T-cells ratio and Treg/T-cell proportions were calculated. Total TIL densities were higher in PWTs and myxosarcomas (median = 225 and 303, respectively). PWTs had higher T-cell density but lower Treg proportion (median = 152 and 7.6% respectively). Myxosarcomas had higher Treg densities and B/T-cell ratios (median = 24.4 and 1.57, respectively). No association with grade was found among STSs as a group. In myxosarcomas, higher grade was significantly associated with higher total TILs, and CD20+ and FoxP3+ cell densities ( p < .05). The results suggest that PWTs and myxosarcomas may represent the most immunogenic STS types. Myxosarcomas elicit a B-cell and Treg-rich immune response; PWTs stimulate a T-cell-rich and Treg-poor reaction. The immune system response may contribute to the more aggressive behavior of myxosarcomas and the more indolent course of PWTs.

To investigate the influence of different toothbrushing (with dentifrice) protocols on the progression of erosive tooth wear for in vitro studies.Bovine enamel specimens were randomly distributed into 12 experimental groups (n = 10), according to the study factors: (1) brushing movement (horizontal or circular); (2) slurry diluent (artificial saliva or distilled water); (3) toothpaste dilution ratio (1:2, 1:3 or 1:4). A 5-day erosion-abrasion cycling model was performed, each consisting of 4 erosive challenges (0.3 % citric acid, pH=2.6) followed by 60 min exposure to artificial saliva. Brushing with fluoride toothpaste (15 s, 1400 ppm F-, AmF) was carried out 2x/day. Enamel surface loss (SL) was determined by optical profilometry. Data were statistically analyzed with three-way ANOVA and Tukey tests (α = 0.05).SL was lower for the horizontal movement than for the circular (p = 0.044). There were no significant differences among the dilution ratios for artificial saliva. For distilled water, the more concentrated slurry (1:2) presented greater surface loss than the less concentrated slurries (1:3 and 1:4, p = 0.049 and p = 0.014, respectively). Dilutions with artificial saliva at ratios 1:3 and 1:4 presented higher surface loss than with distilled water (p = 0.008 and p < 0.001, respectively); however, for 1:2 ratio, there were no significant differences between the diluents.The in vitro progression of enamel SL was influenced by the brushing movement, as well as the combination of the dilution ratio and the diluent of the toothpaste slurry, and therefore, all these factors must be considered when comparing results from different studies.

An 8-month-old female Lagotto Romagnolo dog was presented for a 1-month history of an initial severe reluctance to move, rapidly progressing to a marked stiff gait and progressive muscular weakness and evolving to tetraparesis, which persuaded the owner to request euthanasia. A primary muscle pathology was supported by necropsy and histopathological findings. Macroscopically, the muscles were moderately atrophic, except for the diaphragm and the neck muscles, which were markedly thickened. Histologically, all the skeletal muscles examined showed atrophy, hypertrophy, necrosis with calcification of the fibers, and mild fibrosis and inflammation. On immunohistochemistry, all three dystrophin domains and sarcoglycan proteins were absent. On Western blot analysis, no band was present for delta sarcoglycan. We sequenced the genome of the affected dog and compared the data to more than 900 control genomes of different dog breeds. Genetic analysis revealed a homozygous private protein-changing variant in the SGCD gene encoding delta- sarcoglycan in the affected dog. The variant was predicted to induce a SGCD:p.(Leu242Pro) change in the protein. In silico tools predicted the change to be deleterious. Other 770 Lagotto Romagnolo dogs were genotyped for the variant and all found to be homozygous wild type. Based on current knowledge of gene function in other mammalian species, including humans, hamsters, and dogs, we propose the SGCD missense variant as the causative variant of the observed form of muscular dystrophy in the index case. The absence of the variant allele in the Lagotto Romagnolo breeding population indicates a rare allele that has appeared recently.