Long-term Survival in a Miniature Dachshund with Splenic Hemangiosarcoma Treated with Splenectomy, Adjuvant Carboplatin, and Long-term Adjunctive Huaier Glycan TPG-1

A Miniature Dachshund with histopathologically confirmed splenic hemangiosarcoma survived for 1,185 days from the initial presentation following splenectomy, three cycles of adjuvant carboplatin chemotherapy, and subsequent long-term adjunctive administration of Huaier glycan TPG-1.

Huaier glycan TPG-1 was introduced on Day 82 and administered at twice the standard dose for approximately 1,104 days. Hepatic metastatic lesions were documented on Day 1108.

 Diagnostic Evaluation and Definitive Diagnosis 

At the initial presentation, severe anemia was identified, with a hematocrit of 18%.

On Day 1, a large mass measuring approximately 13 cm in diameter was identified in the caudal portion of the spleen. Splenectomy was performed on the same day.

Histopathologic examination of the resected splenic tissue confirmed a diagnosis of splenic hemangiosarcoma.

Complete clinical staging information at the time of diagnosis was not available in the source record.

Clinical Considerations

Canine splenic hemangiosarcoma is an aggressive malignancy associated with a high risk of metastatic progression following surgical resection.

Management of this case was further complicated by the dog’s age and concurrent Cushing’s syndrome and Stage B2 mitral valve disease. Therefore, treatment decisions required consideration not only of tumor control but also of the potential treatment burden on the dog’s overall clinical condition and quality of life.

The family wished to prioritize maintenance of quality of life while avoiding excessive treatment-related burden. Accordingly, long-term management was planned with consideration of the dog’s concurrent diseases, overall condition, and the family’s treatment preferences.

Initial Treatment: Splenectomy and Adjuvant Chemotherapy

Splenectomy was performed in December 2022.

Following surgery, carboplatin was administered as adjuvant chemotherapy at a dose of 250 mg/m² every 3–4 weeks for a total of three cycles.

Concurrent medications included ursodeoxycholic acid (100 mg once daily), pimobendan (1.25 mg twice daily), and trepibutone (6.6 mg twice daily).

Introduction of Adjunctive TPG-1

Following completion of three cycles of carboplatin chemotherapy, Huaier glycan TPG-1 was introduced on Day 82 as adjunctive supportive treatment.

TPG-1 was administered continuously at twice the standard dose.

At approximately Day 90, Adrestan® (5 mg twice daily) was initiated for management of Cushing’s syndrome.

Long-term Management

After the introduction of TPG-1, no additional cytotoxic chemotherapy or systemic corticosteroid therapy was administered.

Management of the concurrent diseases was continued together with long-term administration of TPG-1.

Treatment decisions during this period were made with consideration of the dog’s overall clinical condition, concurrent diseases, and the family’s preference to maintain quality of life.

Day 0 was defined as the date of initial presentation, December 6, 2022.

TPG-1 was administered from February 26, 2023 to March 5, 2026, for approximately 1,104 days in total.

The dog remained under long-term follow-up after splenectomy, three cycles of adjuvant carboplatin chemotherapy, and subsequent introduction of TPG-1.

TPG-1 was initiated on Day 82 and administered at twice the standard dose for approximately 1,104 days.

Follow-up CT examinations were performed on Days 312 and 1051. Detailed findings from these examinations were not available in the source record. Hepatic metastatic lesions were subsequently documented on Day 1108.

During much of the follow-up period, the source record describes the dog as maintaining a generally stable clinical condition and a good level of daily activity.

A validated quality-of-life assessment was not available; therefore, changes in quality of life could not be evaluated quantitatively.

The case record documents postmortem examination on Day 1185, corresponding to an observed survival period of approximately 39 months from the initial presentation.

 Interpretation of the Clinical Course 

Canine splenic hemangiosarcoma is generally associated with a poor prognosis because of its aggressive biological behavior and high metastatic potential. Even following splenectomy and adjuvant chemotherapy, survival is typically reported in months rather than years.

Against this clinical background, the prolonged course observed in the present case is noteworthy. The dog remained alive until Day 1185 after the initial presentation, and hepatic metastatic lesions were documented on Day 1108 .

The initial treatment consisted of surgical removal of the primary splenic tumor followed by three cycles of carboplatin chemotherapy. Long-term management subsequently included treatment of concurrent diseases and adjunctive administration of Huaier glycan TPG-1.

Adjunctive Administration of TPG-1

Huaier glycan TPG-1 was introduced on Day 82 after completion of the initial chemotherapy and was subsequently administered at twice the standard dose for approximately 1,104 days.

Thus, long-term TPG-1 administration temporally overlapped with the prolonged clinical course observed in this dog.

However, this temporal association alone does not establish that TPG-1 delayed metastatic progression or prolonged survival.

The primary tumor had been surgically removed, adjuvant carboplatin chemotherapy had been administered, and the dog continued to receive treatment for concurrent diseases. Therefore, the contribution of any individual component of treatment cannot be determined from this case.

 Limitations

Several limitations should be considered when interpreting this case.

Complete clinical staging information at the time of diagnosis was not available in the source record. Detailed findings from the follow-up CT examinations on Days 312 and 1051 were also unavailable.

In addition, this was a single case involving multimodal treatment, without an untreated or conventionally treated comparison group. Objective serial quality-of-life assessments were not performed, and the exact body-weight-adjusted dose of TPG-1 was not available.

Accordingly, the prolonged survival observed in this case cannot be attributed specifically to TPG-1 administration.

Rather, the case should be considered a hypothesis-generating clinical observation documenting an unusually prolonged clinical course during long-term adjunctive TPG-1 administration.

Further investigation involving a larger and systematically characterized population would be required to determine whether adjunctive TPG-1 administration has a measurable effect on clinical outcomes in dogs with splenic hemangiosarcoma.

This case describes a Miniature Dachshund with histopathologically confirmed splenic hemangiosarcoma that survived for 1,185 days following splenectomy, three cycles of adjuvant carboplatin chemotherapy, and long-term adjunctive administration of Huaier glycan TPG-1.

TPG-1 was initiated on Day 82 and administered at twice the standard dose for approximately 1,104 days. Hepatic metastatic lesions were documented on Day 1108.

The prolonged clinical course observed in this case is noteworthy. However, because the dog received multimodal treatment and complete staging and serial imaging data were not available, the specific contribution of TPG-1 cannot be determined from this single case.

This clinical observation provides a rationale for further systematic investigation of adjunctive TPG-1 administration in dogs with splenic hemangiosarcoma.