SNAP T4 Test

Screen for hypo- and hyperthyroidism

Don’t wait for late-stage signs of thyroid disorders.

Screen in-house for canine and equine hypothyroidism and feline hyperthyroidism with the SNAP T4 Test.
Get results in just 15 minutes using plasma.

It’s fully quantitative: monitor the course of thyroid disease, evaluate your patients’ therapeutic responses and better assess disease progression.

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SNAP Total T4 Test - Accurate Results in-house in 15 minutes
In the morning, take out one SNAP Total T4 device and replace it when you use it. 0 minutes
Use plasma from the same sample you draw for chemistries. 2 minutes
Incubate sample and prepare your SNAP Total T4 Test. 6 minutes
Run the SNAP Total T4 Test (average run time). 7 minutes
The SNAP T4 Test lets you:
  • Screen for hypo- and hyperthyroidism and begin treatment or follow-up testing in the same visit.
  • Perform reflex testing immediately: 66–75% of hypothyroid dogs have elevated cholesterol and more than 90% of hyperthyroid cats show increases in ALT or ALKP.1
  • Perform preanaesthetic testing—Hyperthyroid cats can have secondary cardiac disease and hypertension that would indicate changes in preanaesthetic protocol.
  • Monitor medications—Use as part of your protocol to help evaluate the effectiveness of treatment and adjust medications, if necessary.

The SNAP T4 Test uses proven SNAP ELISA technology to ensure the accuracy you need for confident diagnoses.



A reliable, accurate in-house testing option for immediate T4 results

The measurement of total thyroxine (T4) concentrations is a widely accepted screening tool for the analysis of thyroid function in veterinary medicine. The SNAP T4 Test allows you to measure T4 concentrations in-house, providing the convenience of timely results and the ability to modify medications or diagnostic options during the patient appointment.

Correlation of IDEXX SNAP T4 with radioimmunoassay2

Each SNAP T4 lot is tested with canine and feline serum from both healthy animals and those with thyroid disease. The IDEXX internal calibration process ensures that each lot of T4 maintains a high level of performance and will provide accurate results for patient samples across all areas of the range.

The data presented shows excellent clinical agreement between serum T4 concentrations measured by the SNAP T4 Test and radioimmunoassay (RIA). The correlation coefficient (r) is a measure of how well a linear equation depicts the relationship between two variables. An r value of 0.92 indicates excellent overall agreement between T4 concentrations measured by SNAP and T4 concentrations measured by RIA.


How To/Resources

How to

1. Pipette the sample (serum or plasma) and add the conjugate.

2. Gently invert the tube 3 or 4 times to mix the sample and conjugate.

3. Incubate the sample for 5 minutes.

4. Pour the sample into the SNAP® device.

5. When colour first appears in the activation circle, press firmly to activate. You will hear a distinct “snap.”

6. Insert the SNAP device into the analyser.

View the testing protocols for detailed instructions.

The SNAP T4/Total T4 Test measures total thyroxine, commonly referred to as “total T4” or “T4.”

Hyperthyroidism is a syndrome resulting from excessive production of thyroid hormones, resulting in an increased basal metabolism. Hyperthyroidism is the most common endocrinopathy in cats, but is very rare in dogs. Common clinical signs include weight loss, polyphagia, increased activity/restlessness/nervousness, hair loss/unkempt coat, polyuria/polydipsia, vomiting/diarrhea/bulky stools. Polycythemia, increased liver enzymes (ALT/ALKP) and hypokalemia are common laboratory findings.

Hyperthyroidism occurs in middle- to old-aged cats with a mean age of 11–13 years. It is rare in younger cats, but any cat over 4 years of age with compatible clinical signs should be screened. All cats over 7 years of age should be routinely screened for hyperthyroidism.

There are three primary treatment options available for hyperthyroid cats:

  • Medical therapy
  • Surgical removal of the thyroid gland (thyroidectomy: uncommon in North America)
  • Radioactive iodine treatment

Yes, the SNAP T4/Total TTest is fully quantitative and enables you to monitor response to treatment. With the ability to monitor T4 levels in-house, you can make immediate adjustments to thyroid medication and discuss the course of illness and treatment while the client and patient are present.

Hypothyroidism is a syndrome resulting from inadequate production and secretion of thyroid hormone by the thyroid gland. Hypothyroidism is the most common endocrinopathy in dogs but very rare in cats. Common clinical signs include lethargy, inactivity, weight gain, cold intolerance, hair loss or excessive shedding, lack of hair regrowth following clipping, dry or lusterless hair coat, excessive scaling, hyperpigmentation, recurrent skin infections. Common laboratory findings include a mild nonregenerative anemia and hypercholesterolemia.

The onset of clinical signs can occur at varying ages but generally appear during middle age (4–10 years). Some high-risk and large- or giant-breed dogs can develop signs at an earlier age (2–3 years). All dogs with compatible clinical signs should be screened for hypothyroidism.

The treatment of hypothyroidism involves thyroid supplement therapy. The goal is to treat the dog with the lowest possible dose that alleviates clinical signs and keeps the thyroid concentration in the upper end or slightly above the reference interval at peak levels (approximately 4–6 hours post-pill).

Yes, the SNAP T4/Total T4 Test is fully quantitative and enables you to monitor response to treatment. With the ability to monitor T4 levels in-house, you can make immediate adjustments to thyroid medication and discuss the course of illness and treatment while the client and patient are present.


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  1. Feldman EC, Nelson RW. Canine and Feline Endocrinology and Reproduction. 3rd ed. Philadelphia, PA: WB Saunders; 2004.
  2. Data on file at IDEXX Laboratories, Inc. Westbrook, ME USA