Fecal Dx antigen testing

Case study: Scout

Intestinal parasite antigen testing helps veterinarians find infections the microscope may miss

German shorthair pointer mix sitting on green grass

Background information

Name: Scout
Age: 4 years
Breed: German shorthair pointer mix
Gender: Neutered male

Presenting reason
Scout presented for annual examination, wellness testing, and vaccinations.

His owners reported that he seemed healthy but requested his ears to be checked since he had been swimming regularly in the lake and had experienced ear problems in the past. He was receiving monthly heartworm prevention with a dewormer.

Physical examination
Scout was bright, alert, and responsive. He weighed 62.4 lb and had a body condition score of 3/5. His temperature was 100.8°F. Oral examination revealed grade 2/4 gingivitis and periodontal disease. He also had lower lid entropion of the left eye.

Diagnostic plan

For Scout, as with other patients of similar age and observations, the following diagnostics along with a physical examination provided a good clinical picture:

  • Chemistry panel, including the IDEXX SDMA Test and electrolytes
  • Complete blood count (CBC)
  • SNAP Heartworm RT Test
  • Fecal Dx Antigen Profile (includes fecal ova and parasites and fecal antigen testing)
  • SNAP cPL Test

Diagnostic review

  • Chemistry panel and CBC results were within normal limits.
  • SNAP Heartworm RT Test was negative.
  • No parasites or eggs were seen on the fecal ova and parasites test; however, the hookworm antigen test was positive, indicating the presence of parasites. Scout was diagnosed with a hookworm infection.

Possible next steps

  • Treat with approved anthelmintic.
  • Minimize risk of reinfection by promptly picking up feces, per veterinarian’s recommendation.
  • Maintain a monthly heartworm preventive containing a dewormer year-round to reduce the risk of reinfection and environmental contamination.

Since Scout had been healthy and maintained on a broad-spectrum monthly control product, retesting was not necessary.

Patient reports

Screenshot of Scout's test results in VetConnect PLUS


This case illustrates how an apparently healthy animal can benefit from Fecal Dx antigen testing.

For Scout, hookworm antigen was detected, an infection was present, but no ova were seen. This can occur during the parasite prepatent period and with single-sex infections, and it may be more common with some intestinal nematodes, which are notorious for intermittent egg shedding. This is where Fecal Dx antigen testing can help to overcome some of the limitations of egg detection.

Dogs receiving monthly anthelmintics effective against hookworms may test positive for antigen or have eggs detected in the feces within a 30-day time period. This is not a failure of the monthly control product but may be attributed to the relatively short prepatent period of hookworms following reinfection or the emergence of arrested larvae from the tissues.

Diagram of the lifecycle of hookworm from infection to presentation

Suggested test profiles for wellness visits 

Fecal Dx Antigen Panel (test code 5199)

Hookworm, roundworm, and whipworm antigens by ELISA

Fecal Dx Antigen Panel with Lab 4Dx Plus Test—Canine (test code 31804)

Lab 4Dx Plus Test, hookworm, roundworm, and whipworm antigens by ELISA.

See more recommended test codes

Select Fecal Dx antigen testing during every fecal screening

Double the detection of hookworm, roundworm, and whipworm infections, earlier than ever and even when dogs appear healthy.2,3

Learn more about Fecal Dx antigen testing




  1. CAPC guidelines: hookworms. Companion Animals Parasite Council website. Accessed March 28, 2019.
  2. Data on file at IDEXX Laboratories, Inc. Westbrook, Maine USA.
  3. Elsemore DA, Geng J, Flynn L, Cruthers L, Lucio-Forster A, Bowman DD. Enzyme-linked immunosorbent assay for coproantigen detection of Trichuris vulpis in dogs. J Vet Diagn Invest. 2014;26(3):404–411.