Splenic masses are the most frequently encountered intra-abdominal lesions in dogs. The spleen is predisposed to tumor formation due to its rich vascular supply and filtration function. Splenic neoplasms are frequently diagnosed in geriatric dogs and often exhibit aggressive biological behavior (Lee et al., 2018). Many malignant tumors of the spleen in dogs tend to proliferate rapidly and carry a guarded to poor prognosis due to the high likelihood of splenic rupture and metastatic spread (Lee et al., 2018). The reported one-year survival rate for dogs affected with splenic lymphoma is approximately 59.8% (Van stee et al., 2015), whereas dogs diagnosed with splenic hemangiosarcoma generally have a mean survival time (MST) of less than four months. Splenic tumors in dogs may arise from several tissue types, including vascular, lymphoid, fibrous, smooth muscle, myeloid and adipose tissues. Numerous studies have reported that hemangiosarcoma is the most frequently diagnosed splenic tumor in dogs (Story et al., 2020). This neoplasm arises from vascular endothelial cells and is typically aggressive, with an unfavorable prognosis. Non-neoplastic conditions affecting the canine spleen include nodular hyperplasia and splenic hematoma. Nodular hyperplasia is a benign overgrowth of the normal cellular components of the spleen and is among the most frequent causes of splenic mass formation in dogs (Spangler et al., 1992). Clinical signs are often nonspecific and thus imaging modalities such as ultrasonography play a vital role in the localization and characterization of lesions. Ultrasonography is the primary clinical imaging modality for evaluating splenic diseases due to its non-invasive nature, real-time imaging and lack of ionizing radiation. In addition to identifying splenic abnormalities, it helps assess the extent and characteristics of the lesion (Singh et al., 2024). Fine-needle aspiration (FNA) cytopathology is a commonly used, accessible and economical diagnostic technique (Ballegeer et al., 2007). Despite its diagnostic value, some clinicians remain hesitant to perform splenic FNAC due to the belief that aspirating a highly vascular organ may lead to complications. However, several studies in companion animals have demonstrated that splenic FNAC can be performed safely, with no significant complications reported (Stockhaus et al., 1998). For staining and evaluation of the samples, Giemsa stain (Merck), distilled water and 96% ethyl alcohol were used, following the method described by Yilmaz et al. (2006) and Cingi et al. (2020). The slides were examined under a light microscope (Olympus). Cytology and histopathology provide a confirmatory diagnosis. Accurate differentiation between benign and malignant splenic masses is essential for prognosis and therapeutic planning.

Dogs presented to the Small Animal Medicine Outpatient Unit of Madras Veterinary College Teaching Hospital, Madras Veterinary College, Chennai, with suspected splenic disorders were screened for splenic abnormalities for a period of two years from January 2024 to January 2026. Cases showing splenomegaly or splenic masses on imaging were included in the study. A detailed clinical examination was performed and signalment, history, presenting complaints and vital parameters were recorded. Ten apparently healthy dogs presented for vaccination were randomly selected and their blood was collected to obtain normal reference values for comparison of haemato-biochemical parameters under study. Blood samples were collected from the splenic lesion-affected dogs for hematological analysis, including hemoglobin, packed cell volume, total erythrocyte count, total leukocyte count and platelet count. Serum biochemical analysis was performed to determine alanine aminotransferase, total protein, albumin and creatinine levels. Radiographic and ultrasonographic examinations were carried out to evaluate splenic abnormalities. Ultrasonography was performed with an AEROSCAN CD 25 linear, convex, or microconvex transducer and splenic lesions were assessed for size, echogenicity, echotexture, margins, cavitation and evidence of metastasis to regional lymph nodes or other organs. Fine-needle aspiration cytology (FNAC) of splenic lesions was performed under ultrasonographic guidance using a twenty-four-gauge needle. The collected smears were stained with Giemsa stain and examined microscopically for cellular morphology and features suggestive of neoplasia. In selected cases, splenic tissue samples obtained following splenectomy or necropsy were fixed in 10% neutral buffered formalin, processed using routine paraffin-embedding techniques, sectioned at 4-5 µm and stained with hematoxylin and eosin for histopathological examination. The results were subjected to statistical analysis using SPSS 23.00 to perform the Student’s t-test.

Among the 82 dogs examined, anorexia (92.31%) was the most common clinical sign, followed by abdominal distension (73.08%) and abdominal pain (73.08%). Other frequently observed signs included lymphadenopathy (48.08%), respiratory distress (40.38%), cancer cachexia (40.38%) and gastrointestinal signs (38.46%). Less common findings included limb edema (34.62%), open-mouth breathing (30.77%), effusions (19.23%), hematuria (17.31%) and icterus (17.31%), as shown in Fig 1. Similar clinical manifestations have been reported in dogs with splenic tumors, where nonspecific systemic signs such as anorexia, lethargy, abdominal enlargement, weakness and respiratory distress are commonly observed due to splenic mass effect, hemorrhage, or metastatic disease (Spangler and Kass, 1997; Smith, 2003).


       
Hematological evaluation revealed several abnormalities suggestive of systemic involvement associated with splenic neoplasia. Haemato-biochemical parameters were mentioned in Table 1 and 2. The hemoglobin concentration, total erythrocyte count and packed cell volume were decreased compared with normal reference ranges. Anemia is commonly reported in dogs with splenic tumors, particularly hemangiosarcoma and may result from chronic blood loss, hemolysis, or internal hemorrhage associated with splenic rupture (Spangler and Culbertson, 1992; Clifford et al., 2000). The total leukocyte count was markedly elevated, suggesting leukocytosis, which may occur due to inflammation, tissue necrosis, or stress associated with neoplastic conditions (Hammer et al., 1991). In addition, the platelet count was reduced, indicating thrombocytopenia, which is frequently observed in dogs with splenic tumors due to platelet consumption, sequestration in the enlarged spleen, or disseminated intravascular coagulation (Clifford et al., 2000). Serum biochemical analysis showed hypoproteinemia and hypoalbuminemia. These findings may be associated with chronic disease, hemorrhage, or decreased hepatic protein synthesis, which are often reported in dogs with splenic neoplasms (Johnson et al., 1989). The alanine aminotransferase (ALT) and alkaline phosphatase (ALP) levels were markedly elevated, suggesting hepatic involvement or secondary liver damage, which may result from metastasis, hypoxia, or systemic effects of neoplastic disease (Clifford et al., 2000). The serum creatinine concentration was increased, indicating possible renal impairment or reduced renal perfusion, which may occur secondary to systemic illness or shock. However, the total bilirubin concentration (0.6 mg/dL) remained within normal limits, suggesting the absence of severe hepatic dysfunction or biliary obstruction. Similar hematological and biochemical alterations have been reported in dogs with splenic tumors, particularly those with malignant vascular neoplasms (Prymak et al., 1988; Clifford et al., 2000).




       
In the present study, radiographic evaluation of 82 dogs with splenic disorders revealed several characteristic abnormalities associated with splenic enlargement and splenic masses (Fig 2 and 3). Displacement of intestinal loops was the most common finding, observed in 41 dogs (50.00%), likely due to the space-occupying effect of splenic enlargement or splenic masses, which displaced adjacent abdominal viscera. Splenomegaly was noticed in 33 dogs (40.38%), while an abdominal mass suggestive of splenic origin appearing as a soft-tissue opacity in the cranial abdomen was identified in 21 dogs (25.00%). Abdominal effusion was evident in 9 dogs (11.54%), which may be associated with splenic rupture, hemorrhage, or neoplastic conditions. Thoracic radiographs further revealed pulmonary metastasis in 8 dogs (9.62%), suggesting metastatic spread of malignant splenic tumors. The radiographic findings observed in the present study were consistent with previous reports describing splenomegaly, abdominal mass effect and visceral displacement in dogs with splenic disease (Kealy et al., 2011; Thrall, 2018; Withrow et al., 2020). However, some studies on splenic neoplasia in dogs have not emphasized radiographic findings, as ultrasonography and advanced imaging techniques are considered more sensitive for evaluation of splenic lesions (Clifford et al., 2000; Spangler and Culbertson, 1992).




       
Ultrasonographic examination of 82 dogs with splenic tumors revealed splenomegaly in the majority of cases (78.85%), making it the most common ultrasonographic finding (Fig 4-7). Irregular margins of splenic lesions were observed in 61.54% of dogs, which may be associated with infiltrative or aggressive splenic masses such as hemangiosarcoma or other malignant neoplasms (Wrigley et al., 1988; Penninck and d’Anjou, 2015). Metastasis to regional lymph nodes was detected in 50.00% of dogs, while heterogeneous splenic masses were identified in 40.38% of cases. Additionally, a reticulated splenic parenchymal pattern was observed in 36.54% of dogs in the present study. This reticulated or mottled echotexture has been reported as a characteristic ultrasonographic feature in dogs with splenic lymphoma, reflecting diffuse infiltration of neoplastic lymphoid cells within the splenic parenchyma (Lamb et al., 1991; Penninck and d’Anjou, 2015). Multifocal splenic nodules were observed in 34.62% of cases, while metastasis to other abdominal organs was detected in 34.62% of dogs. Solitary splenic nodules and abdominal effusion were each observed in 23.08% of cases. The findings of the present study demonstrate that ultrasonography plays a crucial role in the detection and characterization of splenic lesions in dogs. These observations are consistent with the reports of Nyland and Mattoon (2015) and Thrall (2018), who stated that ultrasonography is the imaging modality of choice for evaluating splenic masses in dogs, as it enables detailed assessment of splenic size, parenchymal echotexture, focal nodules and metastatic lesions within the abdomen.








       
In the present study, a comparative evaluation of ultrasonographic findings with cytological and histopathological diagnoses was performed in 19 dogs to assess the reliability of ultrasonography for detecting and preliminarily characterizing splenic tumors (Table 3, Fig 8-11). Dogs with heterogeneous, cavitary splenic masses were ultrasonographically suspected of having hemangiosarcoma (n = 4); however, confirmatory diagnosis revealed hemangiosarcoma in 3 cases and a hemorrhagic cyst with lymphoid hyperplasia in 1 case. Cavitated or heterogeneous splenic masses are commonly associated with hemangiosarcoma due to intralesional hemorrhage and necrosis (Wrigley et al., 1988; Penninck and d’Anjou, 2015). In cases with multifocal hypoechoic, isoechoic, or hyperechoic nodules, ultrasonography suggested hemangioma or hematoma (n=6). Cytological and histopathological examination confirmed histiocytic sarcoma in 2 cases, hemangioma in 2 cases, hematoma in 1 case and cavernous hemangioma in 1 case. Multifocal splenic nodules with variable echogenicity have been described in both benign and malignant splenic conditions and often require cytologic or histologic confirmation for definitive diagnosis (Nyland and Mattoon, 2015; Thrall, 2018). Similarly, solitary hypoechoic, isoechoic, or hyperechoic splenic nodules were ultrasonographically suspected to be hemangiomas or hematomas (n=3), whereas confirmatory diagnosis revealed a splenic cyst in one case and a hematoma in two cases. Solitary splenic nodules detected on ultrasonography may represent a wide range of conditions, including hematoma, hemangioma, cysts, or neoplasia (Penninck and d’Anjou, 2015). A reticulated pattern of splenic parenchyma was ultrasonographically suspected to represent splenic lymphoma (n=6). However, cytological and histopathological examination confirmed splenitis in two cases and splenic lymphoma in four cases. Bharath et al. (2024) reported that abdominal ultrasonography of multicentric lymphoma cases revealed enlargement of the mesenteric lymph nodes and a honeycomb pattern in the spleen, suggestive of splenic lymphoma. Overall, ultrasonography proved to be a valuable imaging modality for detecting and preliminarily characterizing splenic lesions in dogs. Although ultrasonography can identify morphological patterns suggestive of specific splenic diseases, definitive diagnosis often requires cytological or histopathological confirmation due to overlapping ultrasonographic appearances among different splenic pathologies. Nevertheless, Ultrasonography proved to be a valuable non-invasive diagnostic tool for detecting, characterizing and assessing the extent of splenic lesions and metastatic involvement.

Splenic tumors in dogs often present with nonspecific clinical signs, making early diagnosis essential. Ultrasonography proved to be a valuable, non-invasive tool for early detection and characterization of splenic lesions, aiding in identifying key features and guiding further diagnostics. Although definitive confirmation requires cytological or histopathological evaluation, ultrasonography serves as an indispensable first-line diagnostic tool. Early ultrasonographic screening in suspected cases enables timely clinical decision-making and therapeutic intervention, ultimately improving the prognosis and survival outcomes in dogs with splenic tumors.

All authors were actively involved in developing the study concept and designing the research framework.  The authors are thankful to the authorities of Madras Veterinary College, Chennai, for providing the facilities and funding to carry out the work.
 
Disclaimers
 
The views and conclusions expressed in this study are solely those of the authors and do not necessarily represent the views of their affiliated organizations. The authors are responsible for the accuracy of the data presented.
 
Informed consent
 
The study was based on clinical cases presented to the Veterinary Teaching Hospital and all procedures were performed as part of routine diagnostic and therapeutic management with approval from the University Authorities.

The authors declare no conflict of interest.