Improving Immune-Mediated Thrombocytopenia Treatment in Dogs
May 27, 2022
Veterinary Specialty Hospital – North County (San Marcos, CA) is excited to announce a new clinical trial aimed at transforming the treatment in dogs diagnosed with immune-mediated thrombocytopenia (ITP). This study, focused on improving both short and long-term outcomes, represents a cutting-edge approach to managing this challenging condition. VSH-North County is at the forefront of veterinary research, offering hope and advanced care for pets facing serious health issues. In this blog you will:
- Learn about the new clinical trial that is now available for dogs diagnosed with ITP at VSH-North County and UC Davis.
- Explore the effectiveness of partial splenic artery embolization (PSAE) as a potential treatment for ITP in dogs.
- Discover the range of studies at VSH-North County, including those targeting pulmonary metastasis, hemangiosarcoma, and other serious conditions.
- Learn how pet owners interested in clinical trials can fill out an eligibility form to see if their pet qualifies for this or other ongoing studies.
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
Figure 1: Celiac artery angiogram demonstrating normal blood flow to the splenic a., left gastric a., and common hepatic artery. Cranial is the top of the image, right lateral is to the left of the image. This angiogram was performed on a patient undergoing a transcatheter arterial chemoembolization for a large right sided liver tumor.
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.
Figure 2: Computed tomography arterial angiogram demonstrating splenic artery branching off the celiac artery (arrows). Upper left image is the patient in sagittal with cranial to the left of the image and the celiac and cranial mesenteric artery can be seen branching off the abdominal aorta. The lower left image is the patient in axial with the common hepatic and splenic branches clearly visible. The right image is the patient in an oblique coronal view demonstrating all main branches off the celiac. All images are captured in a maximal-intensity projection to demonstrate arterial vasculature.
Inclusion Criteria:
- 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.
Exclusion Criteria:
- 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.;)
Compensation:
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
cthomson@ethosvet.com
References
- 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).