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BackgroundVector‐borne diseases have an adverse impact on health of dogs, and infected dogs can be sentinels for human infection. Infection with Trypanosoma cruzi, an agent of Chagas disease, causes fatal heart disease in dogs across the southern United States but has been neglected from wide‐scale prevalence studies.ObjectivesTo determine the prevalence of exposure to T. cruzi, Ehrlichia spp., Anaplasma spp., Borrelia burgdorferi, and infection with Dirofilaria immitis among dogs in shelters across Texas and to identify risk factors for T. cruzi seropositivity.AnimalsSix hundred and eight dogs.MethodsThis repeated cross‐sectional study was performed by collecting blood from ~30 dogs during each of the 3 visits to 7 shelters. We tested serum for antibodies to T. cruzi using 2 tests in series and for antibodies to Ehrlichia spp., Anaplasma spp., and B. burgdorferi and D. immitis antigen using the IDEXX SNAP 4DX Plus point‐of‐care test. DNA was extracted from blood clots and tested for T. cruzi DNA and strain type via quantitative polymerase chain reactions (qPCR). We used logistic regression to assess risk factors.ResultsOne hundred ten (18.1%) of 608 dogs were seropositive for T. cruzi. Prevalence of exposure to the other vector‐borne agents was: Ehrlichia spp. 3.6%; Anaplasma spp. 6.9%; B. burgdorferi 0.2%; and D. immitis infection 16.0%. Six of 559 (1.1%) dogs were qPCR‐positive for T. cruzi.Conclusions and Clinical Importance T. cruzi seroprevalence was comparable to D. immitis prevalence and higher than seroprevalence of the tick‐borne pathogens. T. cruzi is an underrecognized health threat to dogs across Texas and possibly other southern states where triatomine vectors are endemic.

Highlights Prevalence of adult heartworm (HW) infection was 4 % in cats and 28 % in dogs. Combining antigen and antibody testing led to an overall 19 % positive cats. Prevalence did not differ between dogs and cats with added feline antibody testing. Dirofilaria repens microfilariae were identified in one dog and one cat. Acanthocheilonema reconditum microfilariae were identified in four dogs.

The dog described in this report was the first autochthonous canine case of H americana infection in Indiana, to the authors' knowledge; this case has confirmed that the distribution of this parasite in the Midwestern United States is broader than previously known. Increased awareness of the distribution of H americana should aid veterinarians in early, noninvasive diagnosis and appropriate treatment of affected animals. Repeated treatments and recheck fecal examinations may be necessary when managing these cases.

Background Various heartworm (HW) diagnostic testing modalities detect products of, or reactions to, different life cycle stages of Dirofilaria immitis. Microfilariae (Mf) can be directly visualized in blood, antigen (Ag) from immature and adult heartworms may be detected on commercial assays, and antibody (Ab) tests detect the host immune response to larval stages. Ag and Mf tests are commonly used in dogs, which frequently carry adult HW infections, but Ab tests have only been validated for use in cats. In some HW-infected dogs, Ag is blocked by immune complexing leading to false-negative results. Heat-treatment (HT) to disrupt these complexes can increase the sensitivity of HW Ag tests. The aim of this study was to compare different methods for diagnosing HW infection in dogs at high risk using individual and paired diagnostic tests, including an exploration of using Ab tests designed for cats to test canine samples. Methods One hundred stray adult (≥ 2-year-old) dogs in Florida shelters were tested using Mf, HW Ag, and HW Ab tests (feline HW Ab tests currently not commercially validated/approved for use in dogs); two versions of each test platform were used. Results Fourteen dogs tested positive using point-of-care (POC) Ag tests; an additional 2 dogs tested positive with microtiter well assay, and an additional 12 dogs tested positive using HT Ag testing. For individual tests, Ag test sensitivity/specificity compared to HT Ag was 50–57%/100%, and Ab tests were 46–64%/82–94%. Sensitivity estimates for individual tests were higher when comparing to non-HT Ag. Pairing POC Ag tests with Mf tests improved sensitivity without loss of specificity, while pairing POC Ag and Ab tests modestly increased sensitivity at the expense of specificity. Conclusions Screening dogs for HW infection using both POC Ag and Mf detection, which is recommended by the American Heartworm Society, improved diagnostic performance in this study compared to single Ag test use, but may have missed more than one in four infected dogs. The need to improve access to highly accurate, rapid, and inexpensive large-scale HW testing for dogs in animal shelters remains largely unmet by current testing availability. The development of practical and validated protocols that incorporate heat or chemical treatment to disrupt Ag-Ab complexes in POC testing or decreasing the cost and time required for such testing in reference laboratories might provide solutions to this unmet need. Similar studies performed in countries where the prevalence of parasites such as D. repens or A. vasorum is different to the USA could potentially yield very different positive predictive values for both HT and non-HT Ag tests. Graphic abstract

A 22-year-old Quarter Horse mare exhibited neurological signs consisting of head pressing, central blindness, minimal ataxia and dysphagia. Despite treatment, the mare collapsed and died shortly after onset of signs. On necropsy, there were approximately 15 l of free blood in the abdominal cavity. A 12 ¥ 4 cm diameter, irregularly-shaped, nodular, firm, tan/yellow mass was found adhered to the outer surface of the right lateral aspect of the caudal abdominal aorta. A similar mass also affected the caudal aspect of the right kidney. Histopathology of the aortic and renal masses revealed multiple coalescing granulomas containing intralesional nematodes compatible with Halicephalobus gingivalis. Inflammatory cells disrupted the aortic tunica adventitia as well as the outer tunica media. Similar exudate also affected the cerebrum, cerebellum and brainstem. Polymerase chain reaction amplification and sequencing of a portion of the large subunit ribosomal ribonucleic acid gene were performed using previously published primers for H. gingivalis to confirm the identity of the nematode. Although rupture of a blood vessel could not be demonstrated grossly, the histological findings suggest that inflammation may have breached a small calibre artery and caused the haemoabdomen.

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