Texas A&M spotlights wider U.S. risk from canine schistosomiasis

A Texas A&M research effort is reframing how veterinarians think about Heterobilharzia americana, the parasite behind canine schistosomiasis. What was long treated as a relatively rare, geographically narrow diagnosis is now being described by the school’s investigators as more prevalent, more geographically mobile, and easier to miss than many clinicians realize. In a March 11, 2026 VMBS report, Lea Poellmann and Dr. Kathleen Aicher said prevalence was about 24% in parts of the lower Colorado River basin and approached 28% in some Texas populations of water-exposed dogs. (vetmed.tamu.edu)

That message builds on several years of work at Texas A&M. A 2021 retrospective study of 60 dogs found that the availability of fecal PCR changed the clinical picture by enabling more noninvasive diagnosis, including in dogs that were less severely affected than the classic historical cases. Most dogs in that series were diagnosed antemortem, and 81.7% were identified noninvasively using fecal PCR, a shift the authors said likely facilitated earlier recognition. (pmc.ncbi.nlm.nih.gov)

The newer Texas A&M reporting suggests the concern is no longer confined to the Gulf Coast and southern Atlantic states. A 2025 peer-reviewed review by Aicher and Poellmann in Today’s Veterinary Practice said H. americana is expanding its known range across the United States, with new endemic areas in the Southwest prompting prospective prevalence studies. The same article noted high prevalence in dogs exposed to the lower Colorado River basin and emphasized that many infections may be asymptomatic until egg burden and tissue injury accumulate. (todaysveterinarypractice.com)

The Drake Project is the organizing framework behind much of this work. Texas A&M’s GI Lab describes it as an investigation into prevalence, diagnostics, and treatment for H. americana in dogs, including active prevalence studies in high-risk Labrador retrievers in Texas. The project was inspired by the loss of a Labrador retriever named Drake, according to Texas A&M’s November 24, 2025 coverage of Poellmann’s Three Minute Thesis presentation. That presentation described the project as an effort to map a freshwater parasite in the Southwest and protect dogs through better understanding of its spread. (vetmed.tamu.edu)

Clinically, the research reinforces that veterinarians may need a lower threshold for suspicion. CAPC recommends considering canine schistosomiasis in dogs with persistent diarrhea, vomiting, hepatopathy, hypercalcemia, and weight loss, while Texas A&M’s recent outreach stresses that infection is not limited to retrievers or other expected “water breeds.” In the 60-dog retrospective series, hypercalcemia was present in only 11.6% of dogs, far lower than older case reports had implied, suggesting the historical association may have reflected diagnostic bias toward more advanced disease. The same study found GI or hepatic ultrasonographic abnormalities in 83% of dogs examined, and pinpoint hyperechoic foci in 64.4%. (capcvet.org)

Diagnostic and treatment limitations remain important. Texas A&M’s GI Lab says its fecal PCR offers a sensitive, specific molecular option, and the 2021 case series suggests PCR has largely supplanted sedimentation at some referral centers, though the authors also noted that large comparative studies against traditional methods are still lacking. Treatment typically relies on praziquantel plus fenbendazole, but outcomes are imperfect: in the retrospective series, many dogs required repeat treatment, and follow-up PCR data showed that a single course was often not curative. CAPC likewise notes that treatment is not always effective, particularly when fibrosis and mineralization are already advanced. (vetmed.tamu.edu)

For veterinary professionals, the significance is practical. This is a reminder that freshwater exposure history matters, that breed stereotypes can mislead, and that a negative routine fecal test should not end the workup in the right patient. It also has implications for client communication: pet parents may associate risk with dramatic illness, when in reality some infected dogs are initially silent carriers. Earlier recognition could mean more targeted testing, earlier treatment, and better counseling on avoiding contaminated freshwater in endemic or emerging areas. (vetmed.tamu.edu)

What to watch: The next meaningful development will likely be publication of the Drake Project’s prospective prevalence data and any validation work around PCR-based screening, along with clearer guidance on which exposed but asymptomatic dogs should be tested and retested after therapy. (vetmed.tamu.edu)