# Ruptured Spleen Causes: Veterinary and Medical Overview A ruptured spleen causes bleeding into the abdominal cavity, and the underlying cause splits into two broad groups: traumatic rupture after a direct blow, and atraumatic (spontaneous) rupture from disease inside the spleen itself. In dogs the leading neoplastic cause is hemangiosarcoma, in horses rupture most often follows trauma or parturition, and in humans infectious disease such as malaria and Epstein-Barr virus mononucleosis dominates the atraumatic category. This article compares those causes across species, explains the anatomy and physiology that make the spleen vulnerable, and gives a decision framework for clinicians and students. The emphasis is on comparative etiology and diagnosis rather than human hospital management. This article is educational and is not a substitute for veterinary diagnosis or treatment. ## What the Spleen Does and Why It Ruptures The spleen is a vascular organ that filters blood, recycles aged red cells, stores platelets, and mounts immune responses against blood-borne organisms. In dogs and cats it is a long, strap-like organ tucked against the greater curvature of the stomach on the left side of the abdomen. In horses it is a flattened, sickle-shaped organ lying to the left of the stomach and dorsal to the left kidney. In cattle it sits on the right side of the rumen, attached to the dorsal abdominal wall. In humans it sits in the left upper quadrant behind the ribs. That anatomy explains the pattern of injury. A large, blood-filled organ suspended by ligaments and sitting close to the body wall is easy to strike with a hoof, a bumper, a bat, or a fist. It is also easy to tear when the organ itself becomes abnormally heavy or friable. Rupture means the capsule, the thin fibrous coat around the spleen, has torn. Blood then leaks into the peritoneal cavity, producing hemoperitoneum. Two mechanisms drive the bleeding. Direct trauma tears the capsule and the underlying pulp at the same time. Atraumatic rupture usually starts as a subcapsular hematoma, a pocket of blood trapped between the capsule and the splenic parenchyma. As that pocket enlarges, the capsule stretches and eventually gives way. A canine model of delayed splenic rupture confirmed this sequence experimentally. Investigators created splenic hematomas in dogs and showed that the hematoma area gradually increased until the capsule ruptured after abdominal impact [1]. That experiment is the clearest demonstration that a spleen can bleed in two stages, first into itself and later into the abdomen. The clinical consequence is hypovolemic shock. Blood loss into the peritoneal cavity is not visible from the outside, so an animal or person can be bleeding heavily while the only external clue is pallor, a racing heart, and a distended or painful abdomen. ## Traumatic Splenic Rupture Traumatic rupture is the most intuitive category. A direct blow compresses the spleen against the rib cage or the spine and tears the capsule. In veterinary practice the classic scenarios are a dog hit by a car, a horse that kicks or is kicked, and a cow that suffers a fall or a collision. In the dairy cattle case series from southern Brazil, external trauma accounted for 1 of 24 splenic ruptures, a reminder that in cattle the traumatic route is real but far less common than disease-driven rupture [2]. Traumatic rupture can be immediate or delayed. The delayed form is the two-stage process described above: the initial impact creates a contained hematoma, the animal seems to recover, and days later the capsule fails. This is why a dog that seems fine after a minor collision still deserves monitoring. In humans, blunt abdominal trauma from motor vehicle collisions, contact sports, and falls is the standard traumatic cause. The spleen is the most commonly injured solid organ in blunt abdominal trauma, a fact that follows directly from its size, its blood content, and its position under the left rib cage. ## Atraumatic Splenic Rupture: The Comparative Picture Atraumatic rupture, also called spontaneous rupture, occurs without a significant impact. The spleen is already abnormal, and the abnormality is what makes it tear. A systematic review of 845 patients classified atraumatic splenic rupture into two groups: atraumatic-idiopathic rupture with a normal spleen, which accounted for 7.0 percent of cases, and atraumatic-pathological rupture, which accounted for 93.0 percent [3]. The same review defined six etiologic groups: neoplastic (30.3 percent), infectious (27.3 percent), inflammatory non-infectious (20.0 percent), drug and treatment related (9.2 percent), mechanical (6.8 percent), and normal spleen (6.4 percent) [3]. That human framework is useful as a checklist, but the species distribution is very different. In dogs, neoplasia dominates. In cattle, infection dominates. In humans, infection and neoplasia share the top of the list. The sections below take each category in turn. ### Neoplastic Causes in Dogs Splenic masses are common in dogs, and they carry a real risk of rupture with life-threatening hemorrhage [4]. A retrospective analysis of 682 canine spleen samples submitted to a regional canine cancer registry between 2014 and 2023 found that non-neoplastic lesions were actually predominant at 54.3 percent, mainly nodular hyperplasia, hematoma, and congestion, while neoplastic lesions accounted for 45.7 percent. Hemangiosarcoma was the most frequent neoplasm at 54.5 percent of neoplasms, followed by other sarcomas, lymphomas, and rare tumors. The mean age at diagnosis was 10.4 years, and large dogs and certain pure breeds carried elevated hemangiosarcoma risk [4]. A large prospective study of 345 dogs with spontaneous hemoperitoneum of splenic origin refined that picture. Benign lesions accounted for 35.7 percent of all dogs, and malignant tumors accounted for 64.3 percent. Within the malignant group, hemangiosarcoma represented 56.2 percent of all dogs, and other malignant tumors represented 8.1 percent. The median weight was 27.9 kg and the median age was 10 years. There was no statistically significant difference in body weight or age between dogs with benign and malignant lesions [5]. That last point matters for clinicians because it means you cannot use age or size alone to predict whether a splenic mass is benign. Canine splenic hemangiosarcoma is a highly malignant vascular neoplasm with rapid growth, marked invasiveness, and early metastatic dissemination [6]. It often stays subclinical until the tumor ruptures and causes hemoperitoneum, which is exactly why rupture is frequently the first sign an owner sees [6]. Splenectomy in these dogs is primarily palliative for hemorrhage control, and adjuvant doxorubicin-based chemotherapy produces only modest improvements in median survival [6]. Lymphoma is the other important neoplastic cause. Splenic marginal zone lymphoma in dogs arises from the marginal zone of B-cell follicles and can progress slowly. In a case series of five dogs, all had stage IV disease and two were symptomatic because of splenic rupture. Four dogs underwent splenectomy with adjuvant doxorubicin, and three of those four died of causes unrelated to lymphoma after 760, 939, and 1,825 days, while the remaining dog was alive and in complete remission after 445 days [7]. That outcome pattern is very different from hemangiosarcoma and shows why histopathology, not imaging alone, guides prognosis. ### Infectious Causes in Cattle and Humans In cattle, infection is the dominant driver. A report of 24 cases of splenic rupture in dairy cattle in southern Brazil found that 16 cases (67 percent) were secondary to babesiosis and 4 cases (17 percent) were due to lymphoma. Together, babesiosis and bovine leukemia virus-associated lymphoma accounted for 84 percent of cases. One case each was attributed to a thrombus, external trauma, and ruptured nodular lymphoid hyperplasia, with one undetermined cause. The typical lesion was a rupture of the splenic capsule associated with marked splenomegaly and a large hematoma between the capsule and the parenchyma. Clinical signs were described in 11 of 24 cases and included apathy, abdominal pain, mucosal pallor, tachycardia, and respiratory distress, but 13 of 24 cases presented as sudden death [2]. In humans, infectious mononucleosis caused by Epstein-Barr virus is the most common cause of spontaneous splenic rupture worldwide [8]. Malaria is the other major infectious cause in endemic regions. Acute HIV infection has also been reported as a cause, with one case describing a 27-year-old man who presented with three days of left shoulder and abdominal pain, no trauma history, and hemoperitoneum from a ruptured spleen requiring splenectomy. His spleen pathology showed enlargement with increased small to intermediate lymphoid cells in the red pulp and reactive follicular lymphoid hyperplasia [9]. The mechanism in infectious rupture is usually splenomegaly plus capsular stretching. An enlarged, congested spleen has a thin, tense capsule that tears under minimal strain, sometimes during something as ordinary as a cough or a bowel movement. ### Inflammatory, Vascular, and Drug-Related Causes Inflammatory non-infectious disorders made up 20.0 percent of the human systematic review cohort [3]. Vasculitis is a recognized example. Splenic rupture has been reported as the presenting manifestation of Wegener granulomatosis, now called granulomatosis with polyangiitis, and isolated cases have been noted in rheumatoid arthritis, systemic lupus erythematosus, and polyarteritis nodosa [10]. Drug and treatment related causes accounted for 9.2 percent of the human cohort [3]. Anticoagulants are the clearest example. A case report described a 64-year-old man on rivaroxaban who presented with faintness and diffuse abdominal cramps, no recent trauma, and hemodynamic instability. Splenic rupture was diagnosed on contrast-enhanced CT, and anatomopathological analysis found no neoplastic, inflammatory, or infectious cause [11]. Antiplatelet therapy is a related risk factor. In one case, a woman in her seventies on antiplatelet therapy for chronic atrial fibrillation developed spontaneous splenic rupture secondary to an occult splenic hamartoma [12]. Hematologic malignancy is another route. Spontaneous splenic rupture has been reported as the index presentation of chronic myeloid leukemia, in a 48-year-old man who arrived with sudden abdominal pain and hypotension. Blood work showed anemia and leukocytosis with blast cells, and contrast-enhanced CT showed splenomegaly with a grade three splenic laceration and subcapsular hematoma with hemoperitoneum [13]. Diffuse large B-cell lymphoma has also presented this way, in a 61-year-old man with an acute abdomen and hypovolemic shock whose CT showed a subcapsular splenic hematoma with free pelvic fluid and a mass in the superior pole of the spleen [14]. Metastatic melanoma is a rare neoplastic cause, reported in a 30-year-old man with acute abdominal pain, mild splenomegaly, and moderate free fluid who underwent splenectomy and was found to have diffuse tumor infiltration [15]. ### Splenic Rupture in Horses In horses, splenic rupture most often follows trauma or parturition. The traumatic route is straightforward: a kick from another horse, a collision with a fence or stall, or a fall. Parturition is the less obvious route. The mechanical strain of foaling, combined with the pressure changes and physical effort of labor, can tear a spleen that is already congested or enlarged. The human systematic review listed mechanical disorders as 6.8 percent of atraumatic cases, a category that includes pregnancy and labor, which supports the obstetric mechanism seen in mares [3]. Horses are also subject to splenic disease that predisposes to rupture, though the veterinary literature on equine splenic rupture is thinner than the canine literature. The clinical presentation is usually colic-like pain, pale mucous membranes, tachycardia, and progressive abdominal distension from hemoperitoneum. ## Splenic Torsion and Splenic Masses Can Mimic Rupture Two conditions deserve separate mention because they look like rupture on presentation but are not the same thing. Splenic torsion occurs when the spleen twists on its vascular pedicle. The organ becomes congested, then infarcted. Dogs with splenic torsion present with acute abdominal pain, vomiting, and sometimes a palpable abdominal mass. On ultrasound the spleen is enlarged and hypoechoic with a twisted pedicle, and free abdominal fluid may be present. The fluid in torsion is often a transudate or a modified transudate rather than pure blood, which is a key discriminator. Splenic torsion is a surgical emergency in its own right, and splenectomy is the treatment. Splenic masses, whether benign or malignant, can bleed into the abdomen without a full capsular tear. Nodular hyperplasia and hematoma are the most common non-neoplastic lesions in dogs, and both can produce subcapsular or intraparenchymal bleeding [4]. A dog with a splenic mass and hemoperitoneum may have a ruptured tumor, or may have a mass that is bleeding from its surface without a discrete capsular defect. ## Hemoperitoneum With a Splenic Mass Is Not Proof of Rupture This is the single most important diagnostic caveat in the article. Finding hemoperitoneum plus a splenic mass on ultrasound does not confirm that the mass ruptured. Confirmation requires identifying a capsular defect, an active contrast blush, or direct surgical visualization of the tear. The staging data reinforce how unreliable imaging can be in this scenario. In a study of 99 dogs with nontraumatic hemoperitoneum secondary to presumed splenic tumor rupture, preoperative ultrasonography identified liver lesions in 20 percent of dogs, but there was no association between those lesions and liver lesions seen during operation. In fact, 22 percent of liver lesions observed during operation were missed on preoperative ultrasonography. The presence of liver lesions on preoperative ultrasound was associated with a higher likelihood of a benign splenic tumor diagnosis, and there was no association between ultrasound-identified liver lesions and metastatic disease on liver biopsy, with a sensitivity of 19 percent and a specificity of 82 percent. Ultrasound also had low sensitivity for detecting intra-abdominal lesions beyond the liver and spleen [16]. The practical takeaway is that ultrasound is a triage tool, not a staging tool. It tells you there is blood and there is a mass. It does not reliably tell you whether the mass ruptured, whether it is benign, or whether there is metastatic disease elsewhere. Histopathology of the excised spleen remains the diagnostic standard [4]. ## Decision Table: Species, Etiology, Imaging, and Splenectomy | Species | Common etiology | Key imaging finding | Splenectomy indicated? | |--|--|--|--| | Dog | Hemangiosarcoma (56.2 percent of malignant splenic tumors), benign lesions (35.7 percent), lymphoma | Hemoperitoneum with a splenic mass, often heterogeneous and vascular on ultrasound | Yes for hemorrhage control in ruptured masses. Primarily palliative for hemangiosarcoma [5][6] | | Cat | Splenic mast cell disease, lymphoma, trauma | Splenomegaly with free abdominal fluid | Yes if hemodynamically unstable or if mass is confirmed | | Horse | Trauma, parturition | Hemoperitoneum with a disrupted splenic contour on ultrasound | Yes in most cases because of the volume of blood loss | | Cow | Babesiosis (67 percent), lymphoma (17 percent) | Splenomegaly with a large subcapsular hematoma | Rarely practical. Most cases present as sudden death [2] | | Human | Infectious (mononucleosis, malaria), neoplastic (30.3 percent), inflammatory (20.0 percent) | Contrast-enhanced CT showing laceration, hemoperitoneum, or active bleeding | Selected cases. Nonoperative management is common in stable patients [12][17][3] | The table compresses a lot of variation. In dogs, the decision to operate is usually driven by hemodynamic instability and the presence of a mass. In cattle, the diagnosis is often made at necropsy because the animal dies before treatment is possible [2]. In humans, contrast-enhanced CT is the preferred modality because it rapidly assesses hemorrhage with or without active bleeding and identifies associated parenchymal abnormalities [17]. ## How the Diagnosis Is Made The diagnostic pathway starts with recognition. A dog with acute collapse, pale gums, a distended abdomen, and a history of a splenic mass is a classic presentation. A horse with colic signs and progressive abdominal distension after foaling is another. A person with left upper quadrant pain radiating to the left shoulder, called Kehr sign, plus hemodynamic instability should raise suspicion for splenic injury [8][14]. Ultrasound is the first-line imaging tool in veterinary practice. It confirms free abdominal fluid and identifies a splenic mass or an irregular splenic contour. In the canine delayed rupture model, conventional ultrasonography showed intra-abdominal free liquid after the hematoma ruptured [1]. Contrast-enhanced ultrasound is an extension of this technique and was used in that model to evaluate rupture severity [1]. In human medicine, multidetector CT is the preferred modality. It offers rapid, high-resolution assessment of hemorrhage, with or without active bleeding, and of associated parenchymal abnormalities [17]. Contrast-enhanced CT plays a pivotal role in confirming splenic injury, identifying predisposing lesions, and guiding management [12]. The following flowchart shows the main decision path from presentation to diagnosis. ```mermaid flowchart TD A[Acute collapse or abdominal pain] --> B[Assess circulation and pallor] B --> C[Abdominal ultrasound] C --> D{Free fluid present} D -->|No| E[Look for other causes] D -->|Yes| F[Sample fluid] F --> G{Bloody fluid} G -->|No| H[Consider torsion or effusion] G -->|Yes| I[Splenic mass or defect] I --> J{Stable or unstable} J -->|Unstable| K[Emergency surgery] J -->|Stable| L[CT or contrast imaging] L --> M[Confirm capsular defect] M --> N[Histopathology of spleen] ``` ## Clinical Relevance, Limitations and Common Mistakes The most common mistake is treating hemoperitoneum plus a splenic mass as proof of rupture. It is not. You need a capsular defect, active contrast extravasation, or surgical confirmation. This distinction matters because a bleeding mass that has not ruptured may still be a surgical candidate, but the prognosis and the staging conversation are different. The second mistake is assuming that a large or old dog with a splenic mass must have hemangiosarcoma. The prospective data show that benign lesions accounted for 35.7 percent of dogs with spontaneous hemoperitoneum of splenic origin, and there was no statistically significant difference in age or weight between benign and malignant groups [5]. A clinician who counsels euthanasia based on signalment alone may be wrong more than a third of the time. The third mistake is over-reading preoperative ultrasound. Liver lesions seen on ultrasound in these dogs are more often benign and do not reliably predict metastatic disease, with a sensitivity of 19 percent for detecting metastasis on biopsy [16]. Staging decisions should not rest on ultrasound alone. The fourth mistake is missing the delayed rupture window. A dog or horse that seems stable after trauma can deteriorate days later when a subcapsular hematoma decompresses [1]. Discharge instructions after abdominal trauma should include specific warning signs: pale gums, weakness, a distended abdomen, and rapid breathing. Limitations of the current evidence are real. The veterinary literature on equine splenic rupture is sparse compared with the canine literature, and much of what is known about equine rupture comes from trauma and parturition case reports rather than controlled studies. The cattle data come from a single regional necropsy series in southern Brazil, so the proportions of babesiosis and lymphoma may not transfer to other regions with different disease prevalence [2]. The human etiologic proportions come from a systematic review covering 1980 to 2008, and the distribution of causes may have shifted since then with changes in anticoagulant use and improved imaging [3]. The canine hemangiosarcoma survival data remain discouraging, and no therapy has produced consistent long-term benefit [6]. Individual cases need a veterinarian. The decision to operate, to stage, or to euthanize depends on the specific animal, the specific imaging, and the specific histopathology. ## Frequently Asked Questions ### What is the most common cause of a ruptured spleen in dogs? Hemangiosarcoma is the most common neoplastic cause in dogs, representing 56.2 percent of malignant splenic tumors in a prospective cohort of 345 dogs [5]. Benign lesions such as nodular hyperplasia and hematoma are also common and accounted for 35.7 percent of that cohort. ### Can a spleen rupture without trauma? Yes. Atraumatic or spontaneous rupture occurs when the spleen is already abnormal from infection, neoplasia, inflammation, or medication. In a systematic review of 845 patients, 93.0 percent of atraumatic ruptures had an identifiable underlying cause [3]. ### Why does splenic rupture cause shoulder pain in people? Blood irritates the diaphragm, and the diaphragm shares nerve supply with the shoulder region through the phrenic nerve. This referred pain, called Kehr sign, is a classic clue in human splenic injury [14]. ### Is splenectomy always necessary after splenic rupture? No. The decision depends on hemodynamic stability, the underlying cause, and the degree of injury. In the human systematic review, 84.1 percent of patients underwent total splenectomy, 1.2 percent had organ-preserving surgery, and 14.7 percent were managed conservatively [3]. ### What is the difference between splenic torsion and splenic rupture? Splenic torsion is a twist of the spleen on its vascular pedicle that causes congestion and infarction. Splenic rupture is a tear in the capsule that causes bleeding. Both cause acute abdominal pain and can produce free abdominal fluid, but the fluid in torsion is usually not pure blood. ### Can a splenic mass bleed without rupturing? Yes. A mass can bleed from its surface or into its own parenchyma without a full capsular tear. This is why hemoperitoneum plus a splenic mass on ultrasound is not diagnostic of rupture without confirming a capsular defect [16]. ### What causes splenic rupture in horses? Trauma and parturition are the two most common settings. The mechanical strain of foaling can tear a spleen that is already congested or enlarged, and kicks or collisions are the direct traumatic route. ### How accurate is ultrasound for staging splenic tumors in dogs? Ultrasound has low sensitivity for detecting metastatic disease. In one study, preoperative ultrasound had a sensitivity of 19 percent and a specificity of 82 percent for identifying metastatic disease on liver biopsy, and it missed 22 percent of liver lesions seen during operation [16]. ## Related Articles - [Dog Barking at Night: Medical Causes vs. Behavioral](/knowledge/veterinary-medicine/anxiety-and-behavior-support/dog-barking-at-night-medical-or-behavioral) - [Why Is My Cat Peeing on the Couch? Medical and Behavioral Causes](/knowledge/veterinary-medicine/anxiety-and-behavior-support/cat-peeing-on-couch) - [Cytology of the Liver and Spleen in Veterinary Patients](/knowledge/veterinary-medicine/diagnostics/cytology-of-the-liver-and-spleen-in-veterinary-patients-when-to-aspirate-and-how-to-interpret-the-fi) - [Cytology of the Liver and Spleen: Diagnostic Utility and Interpretation](/knowledge/veterinary-medicine/clinical-pathology/cytology-liver-spleen-veterinary) - [Why Is My Cat Suddenly Aggressive? Medical Causes to Rule Out](/knowledge/veterinary-medicine/anxiety-and-behavior-support/cat-sudden-aggression-medical-causes) - [Cat Litter Box Problems: Medical Causes vs. Behavioral](/knowledge/veterinary-medicine/anxiety-and-behavior-support/cat-litter-box-problems-medical-or-behavioral) - [Head Anatomy: Bones, Muscles and Nerves Overview](/knowledge/veterinary-medicine/veterinary-anatomy-physiology/head-anatomy-bones-muscles-and-nerves-overview) - [Dura Mater Anatomy and Function: Vet Neuro Overview](/knowledge/veterinary-medicine/veterinary-anatomy-physiology/dura-mater-anatomy-and-function-vet-neuro-overview) ## Sources 1. [Evaluation and establishment of a canine model of delayed splenic rupture using contrast-enhanced ultrasound.](https://pubmed.ncbi.nlm.nih.gov/22710316/) 2. [Splenic rupture in dairy cattle: Report of 24 cases.](https://pubmed.ncbi.nlm.nih.gov/39189346/) 3. [Systematic review of atraumatic splenic rupture.](https://pubmed.ncbi.nlm.nih.gov/19787754/) 4. [Epidemiology of Splenic Lesions in Dogs Undergoing Splenectomy-Pathological Characterization and Risk Factors.](https://pubmed.ncbi.nlm.nih.gov/41600720/) 5. [A prospective observational study of 345 canines with ruptured splenic tumors suggests benign lesions are more common than previously reported.](https://pubmed.ncbi.nlm.nih.gov/40334697/) 6. [Canine Splenic Hemangiosarcoma: Biological Behavior, Clinical Challenges and Therapeutic Limitations.](https://pubmed.ncbi.nlm.nih.gov/41828985/) 7. [Splenic marginal zone lymphoma in 5 dogs (2001-2008).](https://pubmed.ncbi.nlm.nih.gov/21092007/) 8. [Atraumatic splenic rupture: a case report.](https://pubmed.ncbi.nlm.nih.gov/39380875/) 9. [Atraumatic splenic rupture: an unusual manifestation of acute HIV infection.](https://pubmed.ncbi.nlm.nih.gov/21711142/) 10. [Splenic rupture as the presenting manifestation of vasculitis.](https://pubmed.ncbi.nlm.nih.gov/11965595/) 11. [Atraumatic splenic rupture in a patient treated with rivaroxaban: A case report and a narrative review.](https://pubmed.ncbi.nlm.nih.gov/36348987/) 12. [Beyond trauma: a case-based imaging review of spontaneous splenic rupture.](https://pubmed.ncbi.nlm.nih.gov/41602203/) 13. [A Rare Case of Spontaneous Splenic Rupture as the Index Presentation of Chronic Myeloid Leukemia.](https://pubmed.ncbi.nlm.nih.gov/34976446/) 14. [Spontaneous splenic rupture: a rare first presentation of diffuse large B cell lymphoma.](https://pubmed.ncbi.nlm.nih.gov/31451478/) 15. [Spontaneous splenic rupture in melanoma.](https://pubmed.ncbi.nlm.nih.gov/24795827/) 16. [Ultrasonographic liver nodules are more often benign lesions in dogs with hemoperitoneum secondary to splenic tumor rupture.](https://pubmed.ncbi.nlm.nih.gov/39111340/) 17. [CT of spontaneous atraumatic splenic rupture: etiologies and imaging findings.](https://pubmed.ncbi.nlm.nih.gov/41026341/)