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SNAP Feline Heartworm Antigen Test Kit

This page contains information on SNAP Feline Heartworm Antigen Test Kit for veterinary use.
The information provided typically includes the following:
  • SNAP Feline Heartworm Antigen Test Kit Indications
  • Warnings and cautions for SNAP Feline Heartworm Antigen Test Kit
  • Direction and dosage information for SNAP Feline Heartworm Antigen Test Kit

SNAP Feline Heartworm Antigen Test Kit

This treatment applies to the following species:
Company: Idexx Labs.

Feline Heartworm Antigen Test Kit

For veterinary use only.


SNAP Feline Heartworm Antigen Test Kit is an enzyme immunoassay for the semi-quantitative detection of Dirofilaria immitis (D. immitis) antigen in feline whole blood, serum or plasma. Heartworm disease, caused by the filarial nematode, D. immitis, has a worldwide distribution. The insect vector for D. immitis is the mosquito. Adult worms inhabit the blood and vascular tissue, especially the heart and adjacent blood vessels. D. immitis often interferes with heart functions and blood circulation and may damage other vital organs.1

SNAP is an enzyme immunoassay technology developed by IDEXX Laboratories, Inc. In operation, the conjugate and the test sample are mixed and added to the SNAP device which is then activated, releasing reagents stored within the device. Color development in high and low antigen indicators is proportional to D. immitis antigen concentration in the sample. A Positive Control Spot develops color indicating assay reagents are active. Color development in the Negative Control Spot indicates reactivity unrelated to the disease or an improperly performed test.

Kit Components





1 bottle Anti-HTWM:HRPO Conjugate (Preserved with gentamicin and Kathon)

8.0 mL


SNAP Device

5 or 15

Reagents contained in each device:


Wash Solution (preserved with Kathon)

0.4 mL


Substrate Solution

0.6 mL

Other Components transfer pipettes sample tubes reagent rack


● Store at 2-8°C until expiration date.

● All components must be at room temperature (18-25°C) before running the test. This may take up to 30 minutes, depending upon the temperature in your laboratory. Do not heat.

Precautions and Warnings

● Use a separate sample tube and transfer pipette for each test.

● During manufacturing the bioactive spots are dyed for quality control purposes. This does not interfere with the test results or interpretation.

● All wastes should be properly decontaminated prior to disposal.

● Do not use kit past expiration date and do not intermix components from kits with different serial numbers.

● The SNAP device must be in a horizontal position on a flat surface while the test is performed.

● Do not use a SNAP device that has been activated prior to the addition of sample.

● Male-only heartworm infections typically produce antigen levels that are below the detection capability of this antigen test.

WARNING: Conjugate - H316/P332+P313/EUH208. Causes mild skin irritation. If skin irritation occurs: Get medical advice/attention. Contains Kathon. May produce an allergic reaction.

Sample Information

● Samples must be at room temperature (18-25°C) before beginning test procedure.

● Serum or plasma, either fresh, previously frozen or stored at 2-8°C, may be used in this test.

● Serum or plasma may be stored for up to 7 days at 2-8°C. For longer storage, sample should be frozen (-20°C or colder).

● Previously frozen or older samples must be centrifuged before use.

● Hemolyzed or lypemic samples will not affect results.

● EDTA or heparin in plasma will not affect results.

● Whole blood may be used. Whole blood must be anticoagulated (eg. EDTA, heparin) and may be used either fresh or after refrigeration (2-8°C) for up to one week.

Test Procedure

1. If stored in a refrigerator, allow all components to equilibrate at room temperature (18-25°C) for 30 minutes. Do not heat.

2. Using the pipette provided, dispense 2 drops of sample (whole blood, serum, or plasma) into a new sample tube.

3. Holding the bottle vertical, add 5 drops of conjugate to the sample tube.

4. Cap the sample tube and mix it thoroughly by inverting it 3-5 times.

5. Place the device on a horizontal surface. Add the entire contents of the sample tube to the sample well, being careful not to splash the contents outside of the sample well.
The sample will flow across the result window, reaching the activation circle in 30-60 seconds. Some sample may remain in the sample well.

6. When color FIRST appears in the activation circle, push the activator firmly until it is flush with the device body.

NOTE: Some samples may not flow to the activation circle within 60 seconds, and, therefore, the circle may not turn color. In this case, press the activator after the sample has flowed across the result window.

7. Read test result at ten minutes.

Interpreting Test Result

Positive Result

Any amount of color development in the sample spots indicates a positive result and color intensity is proportional to the heartworm antigen concentration in the sample.

Low Antigen Levels

High Antigen Levels

Negative Result

Only the positive control spot develops color.

Invalid Results

1. Negative Control (safeguard against false positives)-If color in the negative control spot is equal to or darker than the color in the sample spots, the result is invalid and the sample should be retested.

2. No Color Development-If the positive control does not develop color, repeat the test.

3. Background-If the sample is allowed to flow past the activation circle, background color may result.Some background color is normal. However, if colored background obscures the test result, repeat the test.

Study ID

Sample Size

Sample Type

Relative Sensitivity and Specificity
95% Confidence Limit

Kappa Statistic











Sen., 87.5% (95% CL 0.768 - 0.944)

Spec., 100% (95% CL 0.974 - 1.0)


1. Study conducted at IDEXX Laboratories. The 64 positive samples were characterized by necropsy; the 100 negative samples have been non-reactive on all heartworm antigen tests.

Sensitivity and Specificity are based on visual interpretation of SNAP results.

CL= Confidence Limit

1. Rawlings, C.A., et al. 1982. Four Types of Occult Dirofilaria immitis Infection in Dogs. JAVMA. 180: pp.1323-1326.

Symbol Descriptions

IDEXX Technical Support

USA/Canada 1 800 248 2483 • Europe 00800 1234 3399 • Australia 1300 44 33 99

U.S. Vet License No. 313

Product Code 5F20.00

* SNAP is a trademark or a registered trademark of IDEXX Laboratories, Inc. or its affiliates in the United States and/or other countries.

Patent information:

© 2014 IDEXX Laboratories, Inc. All rights reserved.

IDEXX LABORATORIES, One IDEXX Drive, Westbrook, Maine 04092 USA


NAC No.: 1116062.3

Telephone:   207-556-0300
Fax:   207-556-4346
Pet Diagnostics/Order Desk:   800-248-2483
Poultry/Livestock Diagnostics:   800-548-9997
Poultry/Livestock Order Desk:   800-943-3999
Every effort has been made to ensure the accuracy of the SNAP Feline Heartworm Antigen Test Kit information published above. However, it remains the responsibility of the readers to familiarize themselves with the product information contained on the US product label or package insert.

Copyright © 2019 Animalytix LLC. Updated: 2019-09-30