In order to ensure the health of patients, a fecal examination for

Introduction

In order to ensure the health of patients, a fecal examination for 

intestinal parasites is an important part of a regular checkup. 

Regardless of the fecal procedure used, there can be some 

limitations on accurately identifying infections with some parasites. 

Detection of hookworm, roundworm and whipworm can be difficult 

with the current diagnostics. Now IDEXX Reference Laboratories 

has added fecal antigen testing as an additional tool for detecting 

these common parasites. 

Background 

In small-animal practice, hookworms, roundworms and whipworms 

are commonly encountered intestinal parasites in canine and feline 

patients. They each have a unique life cycle, and their prepatent 

period, the time in which they infect a host before laying eggs, may 

range from 14–21 days in hookworms, 14–30 days in roundworms, 

to as long as 74–90 days in whipworms. This prepatent period may 

allow infections to go undetected on fecal flotation, increasing the 

chance for the appearance of clinical signs prior to evidence of 

eggs in the stool.

Prevalence

In dogs and cats, the prevalence of infection with each intestinal 

parasite varies from region to region and tends to occur more 

frequently in shelter animals than in well-cared-for dogs and cats 

that visit the veterinarian on a regular basis. Outdoor pets and 

those that consume prey with possible infective larvae in their 

tissues are also more likely to be infected.

Studies have shown that hookworm and roundworm prevalence in 

pet dogs was 2.5% and 2.2% respectively

1

 and 20.2% and 15.2% 

in shelter dogs.

2

 One study of approximately 1,500 feline fecal 

specimens found that 7.5% of the cats were shown to be infected 

with Toxocara cati.

3

The whipworm prevalence in dogs in the U.S., based on detection 

of eggs in feces, ranges from 1.2% in pet dogs

1

 to 14.3% in shelter 

dogs.

2

 In North America, whipworm infections in cats are rare.

4

Clinical signs 

Some dogs and cats infected with these common intestinal 

parasites may be asymptomatic, but others may develop a variety 

of gastrointestinal signs that depend on the parasite and age of the 

patient. Symptoms may range from mild diarrhea, vomiting and ill 

thrift to severe bloody diarrhea, anemia and occasionally death. 

Current diagnostics

Currently, the most common method for diagnosing intestinal 

parasite infections is fecal flotation, either passive or by 

centrifugation. There are many issues that may complicate the 

diagnosis of infections with this method. One possible complication 

is misidentification. Pollen and other debris may be misidentified 

as eggs. In addition, the inappropriate identification of eggs from 

other species as a result of coprophagy may also occur. One study 

researching this occurrence found that 31.5% Toxocara-positive 

canine fecal specimens were in fact T. cati eggs.

5

 

Another common problem concerns the varying density of the 

different eggs, which makes it difficult for a clinician to select the 

ideal fecal flotation solution to ensure adequate recovery of eggs 

from all potential parasites. 

Yet another challenge with fecal flotation is that this method of 

egg identification lacks the ability to detect infections during the 

prepatent period or with single-sex infections, when eggs are 

simply not present in the infected animal. 

Finally, fecal flotation may not always be reliable as a single test. 

Because many parasites shed eggs intermittently, a specimen from 

an infected animal may still generate a false-negative diagnosis if 

only a single fecal flotation is examined. For all these reasons, there 

is a need to find a better tool for the diagnosis of the most common 

intestinal parasites found in dogs and cats.

New testing options from  

IDEXX Reference Laboratories

Antigen detection is commonly used today to diagnose heartworm 

and Giardia infections, and now it is available for these additional 

parasites. IDEXX Reference Laboratories has developed enzyme-

linked immunosorbent assays (ELISAs) for the detection of 

hookworm, roundworm and whipworm antigens in feces. These 

antigens are secreted from the adult worm and are not present in 

their eggs, which allows for detection of prepatent stages as well 

as the ability to overcome the challenges of intermittent egg laying. 

This early detection during the prepatent period will also reduce 

the frequency of environmental contamination with potentially 

infectious eggs.

Detect more infections

Over 225,000 IDEXX Reference Labs fecal results, consisting of 

both canine and feline specimens,  were analyzed for positive 

nematode results.  These samples were submitted for testing for 

both fecal flotation by centrifugation (fecal O&P) and fecal antigen 

ELISA methods for hookworm, roundworm and whipworm.

Hookworm eggs were detected in 1.7% of the specimens.

The hookworm-specific antigen ELISA was positive in an additional 

2.0% of specimens that were negative for hookworm eggs, thus 

bringing the total hookworm detection with the combined O&P and 

ELISA testing to 3.7%.

 

Roundworm (ascarid) eggs were detected in 2.2% of the 

specimens.The roundworm-specific antigen ELISA was positive in 

an additional 1.3% of specimens that were negative for roundworm 

(ascarid)

Intestinal parasite antigen testing— 

the next generation of fecal testing

Diagnostic update • January 2016

Detect infections earlier

Because of the lack of egg detection with fecal O&P testing 

during the prepatent period and single-sex infections, many 

parasite infections may go undetected for a period of time and, 

therefore, create a difficulty in correlating clinical signs to fecal test 

results. In an experimental infection study conducted at IDEXX, 

the fecal antigen ELISAs were able to detect infection during this 

prepatent stage. 

The graph below illustrates the identification of a whipworm 

infection approximately 30 days before fecal O&P testing when 

using the whipworm-specific antigen ELISA.

Treatment

There are a variety of anthelmintic products available for both 

treatment and control of hookworm, roundworm and whipworm 

infections. Please see the current Companion Animal Parasite 

Council (CAPC) for recommendations for guidance.

6 

Public health considerations and  

preventive measures

Because of the zoonotic potential of these parasites, most 

commonly hookworm and roundworm, immediate disposal 

of feces is important. This will also reduce the likelihood of 

reinfections and prevent the long-term contamination of the 

environment. Monthly anthelmintic medications can be helpful in 

preventing the continuation of the cycle.

Ordering information

Test code

Test name and contents

24639

Fecal Panel (Comprehensive)

Fecal ova and parasites, Giardia antigen by ELISA, reflex 

hookworm, roundworm and whipworm antigens by ELISA 

if indicated. If the fecal ova and parasites are negative for 

hookworms, roundworms or whipworms, the fecal antigen by 

ELISA for the respective parasite will be automatically performed 

at no additional charge.

 3–5 g fresh feces in a clean plastic container

5013

Fecal Panel (Standard)

Fecal ova and parasites, reflex hookworm, roundworm and 

whipworm antigens by ELISA if indicated. If the fecal ova and 

parasites is negative for hookworms, roundworms or whipworms, 

the fecal antigen by ELISA for the respective parasite will be 

automatically performed at no additional charge.

 3–5 g fresh feces in a clean plastic container

5199

Fecal Antigen Panel

Hookworm, roundworm and whipworm antigens  

by ELISA

 3–5 g (0.2 g minimum) fresh feces in a clean plastic container

5299

Fecal Antigen Panel with Giardia

Giardia, hookworm, roundworm and whipworm antigens by ELISA

 3–5 g (0.2 g minimum) fresh feces in a clean plastic container

Turnaround time: Next day by 10:00 a.m.

Intestinal parasite detection 

ELISA positive  

by day 31

Eggs first 

detected   

by day 69

Eg

gs p

er g

ra

m

3.0

2.5

2.0

1.5

1.0

0.5

0

Days postinfection

EL

IS

A o

ptica

l d

en

si

ty

300

250

200

150

100

50

0

20

40

60

80

100

0

Egg

ELISA

Prepatent infection detection 

 

eggs, thus bringing the total roundworm detection with the 

combined O&P and ELISA testing to 3.5%.

 

Whipworm eggs were detected in 0.7% of the canine specimens.

The whipworm-specific antigen ELISA was positive in an additional 

1.0% of specimens that were negative for whipworm eggs by fecal 

O&P testing, thus bringing the total whipworm

detection with the combined O&P and ELISA testing to 1.7%.

4.0

3.5

3.0

2.5

2.0

1.5

1.0

0.5

0.0

Whipworm

0.7%

1.7%

Hookworm

3.7%

1.7%

Roundworm

3.5%

2.2%

Fecal O&P testing

Combined fecal O&P and antigen ELISA testing

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Contacting IDEXX

Laboratory Customer Support

If you have any questions regarding test codes, turnaround time or 

pricing, please contact our Laboratory Customer Support Team at 

1-888-433-9987.

Expert feedback when you need it

Our team of internal medicine specialists is always available for 

complimentary consultation. Please call 1-888-433-9987 if you 

have questions.

Recommended reading

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.

References

1.   Little SE, Johnson EM, Lewis D, et al. Prevalence of intestinal parasites 

in pet dogs in the United States. Vet Parasitol. 2009;166(1–2):144–152.

2.   Blagburn BL, Lindsay DS, Vaughan JL, et al. Prevalence of canine 

parasites based on fecal flotation. Compend Contin Educ Pract Vet. 

1996;18(5):483–509.

3.   Gates MC, Nolan TJ. Endoparasite prevalence and recurrence across 

different age groups of dogs and cats. Vet Parasitol. 2009;166(1–2): 

153–158.

4.   Bowman  DD.  Georgis’ Parasitology for Veterinarians. 9th ed. St Louis, 

MO: Saunders; 2009:224.

5.   Fahrion AS, Schnyder M, Wichert B, Deplazes P. Toxocara eggs shed 

by dogs and cats and their molecular and morphometric species-

specific identification: is the finding of T. cati eggs shed by dogs of 

epidemiological relevance? Vet Parasitol. 2011;177(1–2):186–189.

6.   Companion Animal Parasite Council. Current advice on parasite 

control: intestinal parasites. www.capcvet.org/capc-recommendations. 

Accessed March 24, 2015.

The information contained herein is intended to provide general guidance 

only. As with any diagnosis or treatment, you should use clinical discretion 

with each patient based on a complete evaluation of the patient, including 

history, physical presentation and complete laboratory data. With respect to 

any drug therapy or monitoring program, you should refer to product inserts 

for a complete description of dosages, indications, interactions and cautions.