Title: Use of an oral moxidectin product (Simparica Trio®) and doxycycline in a non-arsenical adulticide protocol in the treatment of heartworm disease
Clinical Investigators:
Sara E. Gonzalez DVM, MS, DABVP (Canine and Feline Practice)
Jennifer R. Sims DVM
Staci Cannon DVM, MPH, DACVPM, DABVP (Shelter Medicine Practice)
If interested, please contact the UGA Pet Health Center at (706) 542-1984 or email [email protected] for more information or to schedule a visit to see if your dog is eligible.
Study description:
Non-arsenical protocols have been proposed for the treatment of heartworm disease for almost two decades. Doxycycline was incorporated officially into the American Heartworm Society (AHS) treatment guidelines in 2014, solidifying its use in heartworm treatment. Oral ivermectin, as well as transdermal and injectable moxidectin products, in conjunction with doxycycline, have been documented to have efficacy in “slow-kill” protocols; however, oral moxidectin in any of the available FDA-approved formulations has not yet been evaluated. The objective of this study is to determine the efficacy of heartworm treatment by administering an FDA-approved formulation of oral moxidectin and doxycycline to heartworm-positive dogs.
Inclusion criteria:
- Dogs must be heartworm-positive as defined by two positive antigen tests from different companies, or have one positive antigen test and a positive microfilariae test for D. immitis.
- Dogs must be in Class 1 heartworm disease (no visible symptoms, occasional cough)
- Clients must be informed of the recommended AHS three-dose melarsomine protocol but be unable or unwilling to proceed with it and seeking alternative treatment options
Exclusion criteria:
- Dogs with class 2 heartworm disease and above (lethargy, changes on radiographs)
- Dogs with temperament not conducive to routine veterinary visits or recommended activity restriction protocols
- Dogs with life-threatening comorbidities or a history of seizures
- Dogs currently undergoing treatment for heartworm disease
Eligible dogs will be screened for enrollment at the UGA College of Veterinary Medicine Pet Health Center, which will include a physical exam and blood draw for CBC, chemistry, and heartworm testing. Chest radiographs will be recommended by the study veterinarian, but chest radiographs are NOT paid for by the study and are optional.
If enrolled in the study, dogs will receive a single dose of Simparica Trio® orally in clinic, in addition to doxycycline to be given orally twice daily at home for 30 days. Clients will be sent home with 5 additional months of Simparica Trio® to be given orally once monthly. Dogs will have strict activity restrictions recommended during this time and sedative medication may be prescribed to assist in activity restriction if necessary. All dogs will return for recheck visits at the Pet Health Center every 3 months for repeat physical exams and blood collection for heartworm testing. If heartworm tests are negative after two consecutive heat-treated antigen tests 3 months apart, a dog will be considered heartworm negative. If testing continues to be antigen positive at the recheck visits, Simparica Trio® will be refilled at months 6 and 12 and doxycycline will be re-dosed for 30 days at months 7 and 13. If a dog remains antigen positive at 15 months, a traditional heartworm treatment protocol will be recommended.
Costs of the exam fees, full wellness bloodwork (CBC, Chem 15, electrolytes), heartworm testing, and treatment during the study duration (Simparica Trio® and doxycycline) are paid for by study funds. Pet owners are responsible for costs of chest radiographs if elected, and any costs unrelated to the study. All services and medications must be performed/filled through the UGA Pet Health Center for the cost to be covered by the study.
Duration of study:
The study is currently OPEN. Dogs may be enrolled in the study for up to 18 months.
Potential benefits to veterinary medicine:
Evaluation of the efficacy of an oral moxidectin product (Simparica Trio®) along with doxycycline will allow veterinarians to have additional alternative options for a less invasive and lower cost heartworm treatment. If this protocol is successful, it would be applicable immediately for use in spectrum-of-care cases, as the medications already exist and practitioners are already familiar using other formulations of moxidectin.
