SWESR Resource Page for Chagas Disease

This page is intended to help SWESR fosters and adopters—and anyone—learn more about the growing threat of Chagas disease and to show how SWESR is prepared to help you and your Setters respond.

The bad news is that Chagas is a growing threat in the Southern half of the country. Very soon, researchers expect Chagas disease cases to surpass the number of Heartworm cases in Texas. Researchers tell us that as many as 20 percent of shelter dogs test positive for Chagas, and the percentage is likely even higher for dogs from hunting ranches. Since 2020, more than 50 SWESR dogs have been diagnosed with and treated for Chagas. Initially most were rescued in Texas and Oklahoma, but now we are finding positive dogs in places like Colorado, California and Arizona. The number of our dogs testing positive is increasing, and for SWESR, Chagas infections now surpass Heartworm infections for our incoming dogs.

Without treatment, Chagas can be debilitating or fatal. It’s a stealthy disease that can cause acute illness and even sudden death, especially in younger dogs, even before any symptoms show themselves. In older dogs, the disease can cause chronic heart disease. And because Chagas is still not widely recognized or tested for, the symptoms and deaths it causes, are too often misdiagnosed and misunderstood.

But now for the good news. While there is still no approved vaccine nor an FDA approved treatment, thanks to recent advances in veterinary medicine, we are now definitively diagnosing and, as part of an established clinical trial, successfully treating this dangerous disease. SWESR understands that scientific research is dynamic and, working closely with our veterinary partners, we pledge to stay abreast of all development in treatment.

We are now committed to testing and treating every single dog that comes to SWESR, regardless of location. We are committed to following the treatment protocol based on the most recent scientific research. At this time, we have vet clinics in Texas and Oklahoma working with us to test incoming dogs, and we are working hard to find more clinics in all states where we rescue to test and treat.

We are committed to working with the DVM community, the rescue community, and the public at large in helping advance awareness of Chagas and the resources currently available to combat it.

We are committed to supporting our fosters and adopters every step of the way, as they learn about this disease and learn how to care for and cure dogs who have been infected.

 What exactly is Chagas Disease?

If you live in Texas or the South, you’ve probably seen this bug:

It’s commonly called a Kissing Bug, but unfortunately its kiss can be fatal. That’s because these common bugs have about a 50/50 chance of carrying a nasty parasite named Trypanosoma cruzi (T. cruzi) that causes Chagas disease. Chagas invades heart muscle tissue causing severe heart arrhythmia, heart failure, and, if untreated, death.

Chagas is now endemic in Central and South America and in the southern United States, where it’s estimated to infect more than 650,000 dogs each year in Texas and millions more across Southern states. Texas A&M’s website currently identifies eleven different kinds of triatomine (kissing) bugs in the United States, with the highest numbers of the bugs found in Texas, New Mexico, and Arizona.

How is Chagas contracted in dogs?

Chagas disease can infect any mammal through the following pathways:

1. Insect transmission through the feces of an infected kissing bug
2. Vertically through an infected female to her young
3. Blood transfusion
4. Ingesting a dead infected mammal or ingesting a kissing bug

There are no cases reported ever of dog to human transmission. Dogs undergoing Chagas treatment for 2 or more weeks have no circulating parasites and are not able to transmit the disease. The only way the disease could be transmitted during the two-week period is through direct blood to blood contact between both dogs.

Chagas CANNOT be contracted by a dog or any mammal living in the home with an infected dog, nor can it be transmitted by an uninfected dog eating the feces of an infected dog at any time during treatment.

What are the symptoms?

There likely won’t be outwardly obvious symptoms, but an EKG is done prior to starting one of the medications as a precaution. A few dogs have shown early heart irregularities that are not life threatening and can be reversed with treatment. The first month of treatment is when the parasites are cleared from the blood stream and after that month the risk is significantly decreased. The treatment is for a full year to ensure that the parasites are gone from all tissue, not just the blood.

What is SWESR doing about Chagas? 

We are dedicating the resources it takes to take Chagas head on! SWESR was, to our best knowledge, the first Texas rescue to begin routinely testing for Chagas. From diagnostic testing to treatment to retesting, SWESR supports fosters and adopters through the whole process, providing a treatment plan for each dog according to the year-long protocol prescribed by the most expert veterinarians in the field. We supply a treatment plan for all dogs, provide and pay for the medicines and assist in getting all necessary tests done, before, during and after treatment.

What is the typical treatment protocol?

The typical treatment protocol includes the following steps: diagnostic testing, 12 months of treatment (or in the case of puppies, six), post-treatment retesting, and annual follow-up testing. SWESR will send reminders in advance of key treatment and testing milestones. To see a quick overview of all tests and treatments associated with a Chagas diagnosis, see Appendix 1.

While testing and treatment may seem confusing at first and finding clinics and labs is still a challenge, it is all going to get much easier as we move forward and as the science and our local testing capacities in Texas develop. We are excited to see more clinics coming on board in all states where SWESR rescues dogs. And we are deeply appreciative of the fosters and adopters who have already seen infected dogs through the entire process and now see them restored to health. Their experiences will lead the way for many others to see that Chagas can be treated and cured and that neither the infection nor its treatment negatively affect health or longevity.  

What’s next?

SWESR is grateful to work with one of SWESR’s primary veterinary partners, Roy Madigan, DVM, as we prepare to deal with the increasing number of Chagas positive dogs coming into our rescue. Dr. Madigan is an international leader dedicated to finding the most effective tests and treatment of Chagas and is currently helping lead a clinical trial for the world’s first treatment of Chagas disease, in which SWESR and our dogs are participating.  Our hope is that at the conclusion of this important trial the treatment receives FDA approval.

SWESR is also participating in a National Chagas Registry to help determine the actual prevalence of this disease in the canine population. We are also working to help advance broader awareness of Chagas among the DVMs and veterinary clinics we work with, helping more become aware of the dangers of Chagas and to the amazing resources now available to diagnose and treat this disease.

At present, SWESR’s two primary intake clinics in Frisco, TX, and Spring Branch TX, as well as a handful of cooperating veterinarians in Texas and Oklahoma, routinely test all incoming SWESR dogs.

SWESR now uses the most accurate diagnostic test available, the ELISA test, run through the VRL laboratory in San Antonio, TX. Some DVMs may only be aware of the IFA test run through the TVMDL laboratory at Texas A&M, and SWESR will work with them to encourage the more reliable ELISA diagnostic test. SWESR now includes a diagnostic Chagas test on the vetting lists for all incoming dogs and includes a VRL order form to facilitate test processing and payment.

In the future, we hope that testing will become far easier with more clinics and laboratories participating. We also anticipate availability sometime soon of a single annual combined test for both Heartworm and Chagas. And, of course, Dr. Madigan and his fellow researchers have formulated and are in the process of receiving approval for an effective vaccine to prevent this disease, much as we prevent Heartworm disease. But until knowledge of Chagas and its diagnosis, treatment and prevention are far more common, we are responding to the growing crisis of Chagas as best we can, dog by dog, case by case.

SWESR Resource Team

Dr. Roy Madigan, DVM, SWESR’s Chagas Advisory Vet, is available to talk with your Vet, as needed. He is on a mission to educate as many DVMs as possible.

Susan Dunlap provides all medications directly to fosters and adopters. Please give at least 3 weeks advance notice when ordering more medications at susand@swesr.org or at 210-865.6492.

Carla Cooper coordinates SWESR’s Chagas Program with our DVM expert and keeps track of all SWESR dogs undergoing treatment. She sends reminders before treatment milestones and is always available for questions. Contact her at cmcooper49@gmail.com or at 830.837.1215

APPENDIX 1

TESTS and TREATMENTS

• SWESR now uses the most accurate diagnostic test available, the ELISA test, run through the VRL laboratory in San Antonio, TX. Some DVMs may only be aware of the IFA test run through the TVMDL laboratory at Texas A&M, and SWESR will work with them to encourage the more reliable ELISA diagnostic test. SWESR now includes a diagnostic Chagas test on the vetting lists for all incoming dogs and includes a VRL order form to facilitate test processing and payment.

Note to DVMs:

For Dr. Roy Madigan’s recent analysis of the preferability of the ELISA test and overview of SWESR’s participation in the VIDAS Chagas Registry, please see our website at https://swesr.org/swesr-vidas-chagas-registry-q42022/

• 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 in capsule form once a day with food for the length of treatment.
• Amiodarone is first given in tablet form in a loading dose for the first 28 days. After the 28 day loading dose, amiodarone is cut in half for the remaining 11 months of treatment.
• The protocol also calls for an Itraconazole serum test at the 28 day mark to make sure the drug is within the therapeutic range (between 1.5 – 3.0 mg/ml) 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. SWESR will send the order form in advance of testing.
• The protocol also requires at the same time two liver enzyme tests, SAP (ALKP) and ALT, to make sure the liver is tolerating the medications. These tests may be done locally.
• When all results are in, SWESR will send to Dr. Madigan who will review and adjust dosages as needed.

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 (or 6 months in the case of dogs under 12 months), 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 protocol calls for two PCR tests. The two tests can be done in as small an interval of 7 hours in a single day (with one blood draw early in the morning and the second at the end of the day) or in as long an interval as 30 days. SWESR prefers the same day testing to save in mailing costs.

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 will provide order forms in advance of testing.

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 apart, should run about $125 each.  

APPENDIX 2

Roy T. Madigan, DVM

In addition to his private practice, Dr. Roy Madigan is also the Chairman of the Board and founder of Vida Pharmacal, a human and veterinary pharmaceutical company. The company’s focus is the development of novel therapeutics to address emerging parasitic diseases in both humans and animals. Dr. Madigan’s work includes filing the first veterinary drug patent for anti-T. cruzi activity in dogs and conducting pioneering research in studying the curative effects of a drug combination in human heart cells infected with Chagas disease. He is also developing serologic techniques to diagnose T. cruzi infection in dogs.

Dr. Madigan is the principal scientist in the Canine Chagas Treatment Study, Lackland Air Force Base, San Antonio, TX—research into treatment of canine Chagas disease in Unites States Army military working dogs. He is also the director of The Animal Hospital of Smithson Valley in Spring Branch, TX, where he serves as Chief Medical Officer and coordinator for small animal medicine and surgery. He is a member of the Texas Chagas Task Force, Centers for Disease Control, and University of Texas Health Science Center, San Antonio, TX, as the veterinary lead for canine Chagas disease in Texas. The Task Force increases public awareness of Chagas disease by working with healthcare providers, entomologists, marketing, and the public. Dr. Madigan and his family reside in the Texas Hill Country with a pug named Buda, a golden retriever Daisy, and a GSP named Rip.

Check out the website at https://www.vidapharmacal.com