Veterinary Specialty Hospital – North County (in San Marcos, CA) is proud to announce a new funded clinical trial directed at improving short and long-term outcomes of dogs diagnosed with immune-mediated thrombocytopenia (ITP). This study is in addition to the many clinical trials currently open for enrollment, including for patients with pulmonary metastasis, hemangiosarcoma, osteosarcoma, urothelial carcinoma, sepsis/intestinal obstructions, and dysbiosis. If you think your pet might be a good candidate for a clinical trial, fill out the form at the bottom of the study page, a member of our team will be in touch with you to discuss eligibility and next steps.
This study is currently only being performed at VSH-North County (San Marcos, CA) and at UC Davis.
Immune-meditated Thrombocytopenia (ITP)
Immune-mediated thrombocytopenia (ITP) is a disorder characterized by platelet autoantibodies that induce thrombocytopenia and occasionally severe bleeding episodes. The first-line treatment of immune thrombocytopenia usually includes corticosteroids, cytotoxic chemotherapies, and various other immunosuppressive agents2. High doses of steroid therapy may be required, and long-term use can cause potential side effects. Treatments are targeted at rapid increases in circulating platelets to decrease life-threatening bleeding. Prednisone and other immunosuppressive agents have been previously reported to take a median of 7-10 days to reach levels >100,000 platelets/uL.3 The use of adjunctive treatments, such as vincristine or human intravenous immunoglobulin (hIVIG), can decrease this time to 4 days, but may be associated with significant complications such as impaired platelet function4, neutropenia5, prolonged hospitalization (3-22 days)5 and exposure to a protein of human origin. Despite adjunctive treatments, of surviving dogs, roughly 40% may still experience relapse. 6
Partial Splenic Artery Embolization (PSAE)
Embolization of the splenic artery has been used to treat hypersplenism and splenic trauma in humans8-13. A unique observation in these patients was the development of a consistent and prolonged thrombocytosis and erythrocytosis. Partial splenic embolization was subsequently used as a direct treatment for thrombocytopenia (idiopathic, immune-mediated, drug induced, or secondary to other primary disease states). The effectiveness of partial splenic artery embolization (PSAE) for ITP has been reported in humans, with curative responses occurring in >80% of patients 8-13, despite being refractory to traditional steroid therapy. Preclinical studies in dogs have demonstrated the safety of partial splenic artery embolization (PSAE) in healthy purpose-bred dogs14. The primary aim of this study is to describe the procedure of PSAE in dogs diagnosed with spontaneously occurring ITP. A secondary aim will be to define feasibility by the extent and length of effect through serial platelet count monitoring.
- Dogs greater than 4kgs, platelet count <40,000 platelets/uL
- This study is currently only being performed at VSH-North County in San Marcos, CA, and at UC Davis.
- Modified Karnofsky performance status >2, ASA >3, Dogs with known infectious secondary ITP (recent positive for anaplasma spp., ehrlichia spp., bartonella spp., babesia spp., or leptospira spp.;)
The study will pay for the following costs:
- Embolization, postoperative monitoring (up to $6,256)
- Unexpected side effects (up to $3,000)
Costs that owners may be responsible for:
- Pre-enrollment testing (bloodwork, pre-enrollment treatment and hospitalization)
- Procedural costs above $6,256 (expected to be $0 – 2,500)
- Costs for treatments elected outside of the study requirements
The study is financed through a grant from the Veterinary Interventional Radiology and Interventional Endoscopy Society (VIRIES) with support from Ethos Discovery.
UC Davis site coordinator, Bill Culp.
VSH – North County Contact:
Chris Thomson, DVM, DACVS-SA
Surgeon, Surgical Oncology and Minimally Invasive Surgery
- Rozanski, E. A., Callan, M. B., Hughes, D., Sanders, N. & Giger, U. Comparison of platelet count recovery with use of vincristine and prednisone or prednisone alone for treatment for severe immune-mediated thrombocytopenia in dogs. Journal of the American Veterinary Medical Association vol. 220 477–481 (2002).
- Balog, K. et al. A Prospective Randomized Clinical Trial of Vincristine versus Human Intravenous Immunoglobulin for Acute Adjunctive Management of Presumptive Primary Immune-Mediated Thrombocytopenia in Dogs. Journal of Veterinary Internal Medicine vol. 27 536–541 (2013).
- Goggs, R. et al. Lyophilized platelets versus cryopreserved platelets for management of bleeding in thrombocytopenic dogs: A multicenter randomized clinical trial. J. Vet. Intern. Med. 34, 2384–2397 (2020).
- Putsche, J. C. & Kohn, B. Primary Immune-mediated Thrombocytopenia in 30 Dogs (1997–2003). J. Am. Anim. Hosp. Assoc. 44, 250–257 (2008).
- Grau-Bassas, E. R., Kociba, G. J. & Guillermo Couto, C. Vincristine Impairs Platelet Aggregation in Dogs with Lymphoma. Journal of Veterinary Internal Medicine vol. 14 81 (2000).
- LaQuaglia, K. A., Robertson, J. B. & Lunn, K. F. Neutropenia in dogs receiving vincristine for treatment of presumptive immune-mediated thrombocytopenia. J. Vet. Intern. Med. 35, 226–233 (2021).
- Scuderi, M. A., Snead, E., Mehain, S., Waldner, C. & Epp, T. Outcome based on treatment protocol in patients with primary canine immune-mediated thrombocytopenia: 46 cases (2000-2013). Can. Vet. J. 57, 514–518 (2016).
- Best, I. M. Partial splenic embolization for refractory thrombocytopenia. Clin. Pract. 1, e126 (2011).
- Togasaki, E. et al. Long-term efficacy of partial splenic embolization for the treatment of steroid resistant chronic immune thrombocytopenia. Ann. Hematol. 97, 655–662 (2018).
- Miyazaki, M. et al. Partial splenic embolization for the treatment of chronic idiopathic thrombocytopenic purpura. AJR Am. J. Roentgenol. 163, 123–126 (1994).
- Shanmuganathan, K., Mirvis, S. E., Boyd-Kranis, R., Takada, T. & Scalea, T. M. Nonsurgical management of blunt splenic injury: use of CT criteria to select patients for splenic arteriography and potential endovascular therapy. Radiology 217, 75–82 (2000).
- Sangro, B. et al. Partial splenic embolization for the treatment of hypersplenism in cirrhosis. Hepatology vol. 18 309–314 (1993).
- Hidaka, H. Restoration of thrombopoietin production after partial splenic embolization leads to resolution of thrombocytopenia in liver cirrhosis. Hepatology Research vol. 23 265–273 (2002).
- Wright, K. C., Anderson, J. H., Gianturco, C., Wallace, S. & Chuang, V. P. Partial splenic embolization using polyvinyl alcohol foam, dextran, polystyrene, or silicone. An experimental study in dogs. Radiology 142, 351–354 (1982).