Chagas Tests And Treatments

  • There are two tests used to detect the presence of antibodies in the blood and to diagnose Chagas: the first is the ELISA test and the second is the IFA test. SWESR prefers the ELISA test, run through the VRL laboratory in San Antonio, but supports vet clinics who prefer the IFA test, run through the TVMDL laboratory at Texas A&M University.
  • SWESR now includes a diagnostic Chagas test on the vetting lists for all incoming dogs and includes, depending on vet preference, either a VRL form or a TVMDL form to facilitate test processing and payment.  
  • After a dog has received a positive test but before beginning treatment, the protocol recommends an EKG to reveal any heart irregularities.
  • The daily treatment entails dosage of the two drugs that research has proven will eliminate the T. cruzi parasite from the bloodstream, muscle tissue, and other parts of the body. These two drugs, itraconazole and amiodarone, are dosed depending on weight of dog and given orally.
    • Itraconazole is given once a day with a capsule for the length of treatment.
    • Amiodarone is first given in a loading dose of one and a half tablets per day for one month. After the one-month loading dose, amiodarone is cut in half to ¾ of a tablet for the remaining 11 months of treatment.

Susan Dunlap at susand@swesr.com  provides all medications directly to adopters and fosters.

  • The protocol also calls for an Itraconazole serum test at the one-month mark to make sure the drug is within the therapeutic range to effectively treat. The TVMDL lab at Texas A&M runs this test, as do various other laboratories. Draw one ml. of blood serum or plasma before the daily dose for the most accurate measure. The protocol also requires liver function bloodwork to make sure the liver is tolerating the medications. Please inform SWESR of test results, as dosage may need to be adjusted.

SWESR will send a reminder in advance of the Amiodarone drop-down and both the Itraconazole and liver testing requirements before the end of the first month of treatment and will help facilitate and pay for the tests.  

  • Most dogs tolerate the treatment well, and unlike treatment for Heartworm disease, there are no restrictions on activity. But caregivers should keep watch for any weight loss, loss of appetite, vomiting or lethargy.
  • After 365 days from the start of medication, treatment ends. One month after the end of treatment, comes retesting. The test used at this point in the process is a PCR (polymerase chain reaction), a blood serum test that detects genetic material from a specific organism, like T. cruzi. The initial protocol called for two PCR tests, the first 30 days after the treatment is done and the second 60 days. It is now possible to do these two tests in the same day, 30 days after treatment is complete: the first early in the morning and the second toward the end of the afternoon of the same day.

Both of these PCR tests are to be sent to VRL Animal Health Diagnostics in San Antonio, TX. The specific name of the PCR test to be run is T. cruzi kDNA (order code 8583).  The VRL link is  http://www.vrlsat.com/vrl-now-has-canine-trypanosoma-cruzi-t-cruzi-elisa-and-pcr-available-for-our-clients/

SWESR now has an account with VRL, similar to its arrangement with TVMDL, to facilitate PCR testing.

We are happy to say that every Chagas+ dog completing treatment since the beginning of this protocol has tested negative for these final two retests.

  • Finally, the Chagas protocol recommends ongoing testing for all treated dogs with an annual PCR test.
  • SWESR appreciates a cost estimate from all clinics prior to doing blood draw, sample prep and mailing and will pay all charges if in line with standard expectations. We expect that the initial diagnostic test, whether IFA or ELISA, should run around $100. The Itraconazole serum test at 28 days into treatment should run around $175 and the two PCR tests, whether run on the same day or a month a part, should run about $125 each.