Another evidence that the 1/3-2/3 rule for splenic mass is in the presence of hemoperitoneum

A prospective observational study of 345 canines with ruptured splenic tumors suggests benign lesions are more common than previously reported

Elise Ruffoni 1, Samuel Stewart 2, Chand Khanna 2, Christopher Thomson 1 2, Garrett Tougas 2, Joelle Fenger 2, Heather Wilson-Robles 2, Jacob Cawley 2

Background
Spontaneous hemoperitoneum (SH), or nontraumatic blood accumulation in the peritoneal cavity, is a common emergency in dogs, most frequently caused by splenic tumor rupture. Historically, retrospective studies have reported high rates of malignant etiologies, particularly hemangiosarcoma (HSA), in older, large-breed dogs. However, these studies vary in reported malignancy rates and suffer from biases inherent in retrospective designs. This study aimed to provide updated, prospective data to more accurately define the prevalence and types of splenic lesions, with the goal of informing surgical decision-making and improving clinical counseling.

Methods
This was a post hoc analysis of prospectively collected data from 345 dogs enrolled across 30 hospitals in the Ethos-PUSH study between October 2020 and June 2024. Inclusion criteria required SH secondary to a ruptured splenic mass, confirmed by ultrasound and fluid analysis, and no evidence of pulmonary metastasis. All dogs underwent splenectomy, and histopathological evaluation classified tumors into benign, HSA, or other malignant categories. Dogs were staged based on tumor size, rupture, and presence of metastasis. Statistical comparisons of age and weight across groups were conducted using nonparametric methods.

Results
Of the 345 dogs with confirmed splenic pathology, 35.7% had benign lesions, 56.2% had HSA, and 8.1% had other malignant tumors. The most common benign lesion was nodular hyperplasia, and stromal sarcoma was the predominant non-HSA malignancy. No significant differences were observed in age or weight among the three groups. Among HSA cases, 32% had metastases, most commonly in the liver and omentum. Concurrent benign pathology was found in 19.6% of HSA cases. Commonly represented breeds included Labrador Retrievers, Golden Retrievers, and German Shepherd Dogs.

Limitations
The study was limited to dogs with stage II or III disease due to eligibility criteria requiring hemoperitoneum, thus not capturing earlier-stage cases. Dogs with confirmed pulmonary metastasis were excluded, potentially underestimating the true rate of metastatic HSA. Lack of follow-up data for benign cases may miss delayed progression or misclassification. Financial incentives and selective enrollment criteria introduce some degree of enrollment bias.

Conclusions
This prospective study found a higher-than-previously-reported prevalence of benign lesions (35.7%) among dogs with SH secondary to ruptured splenic tumors, challenging the narrative that older, large-breed dogs predominantly have HSA. These findings suggest that benign conditions are more common than assumed and support a more nuanced approach to clinical decision-making. The data advocate for surgery and histopathologic confirmation over euthanasia in appropriate cases, reinforcing the need for evidence-based discussions between veterinarians and pet owners.

Disclaimer: The summary generated in this email was created by an AI large language model. Therefore errors may occur. Reading the article is the best way to understand the scholarly work. The figure presented here remains the property of the publisher or author and subject to the applicable copyright agreement. It is reproduced here as an educational work. If you have any questions or concerns about the work presented here, reply to this email.