One of the health screenings I take very seriously in my breeding program is thyroid testing. It might not get as much attention as hips or eyes, but it’s a crucial piece of the puzzle for responsible Welsh Springer Spaniel breeders. A healthy thyroid means a healthier dog, better fertility, and more reliable temperaments in the puppies we produce. Let’s talk about why thyroid testing matters, the best way to go about it, and why waiting after vaccinations is so important.
Why Thyroid Testing Is Important in Welsh Springers
The thyroid gland regulates metabolism, energy, growth, fertility, coat quality, and even behavior. When it’s not working properly (a condition called hypothyroidism), the effects can ripple through nearly every body system.
In Welsh Springer Spaniels, autoimmune thyroiditis (where the immune system attacks the thyroid) is a concern. It often shows up as:
- Unexplained weight gain or difficulty keeping weight off
- Chronic skin or coat issues
- Changes in energy level
- Behavioral changes like irritability or anxiety
- Fertility problems in breeding dogs
The tricky part? Many of these signs can look like other issues, which is why a thorough thyroid panel is so valuable. By testing, we get a baseline for each dog and can screen for early signs of autoimmune thyroid disease before it becomes obvious.
How to Test Thyroid Properly
A simple “T4 test” at your vet isn’t enough. For a true breeding-quality evaluation, you’ll want a comprehensive thyroid panel that includes:
- Free T4 and Total T4
- T3 levels
- TgAA (thyroglobulin autoantibody) — this one is key for identifying autoimmune thyroiditis
I recommend submitting samples to labs like Michigan State University (MSU) or Hemopet, both of which are widely respected in the breeding community for accuracy and consistency.
Pro tip: If you plan to submit results to the OFA Thyroid Registry, make sure your veterinarian follows OFA’s sample collection guidelines. Results won’t be accepted otherwise.
Why Vaccinations Can Skew Thyroid Results
This is the part many breeders overlook. Vaccinations stimulate the immune system, which can cause temporary thyroid autoantibody production. If you test too soon after a vaccination, you might get a false positive, making it look like your dog has autoimmune thyroiditis when in fact, their immune system is just “revved up” from the vaccine.
That’s why it’s recommended to wait at least 6 months after any vaccination before testing thyroid. Personally, I prefer waiting a full year to be absolutely certain I’m getting a reliable reading.
For young dogs, this means planning ahead:
- Complete their puppy vaccination series
- Allow a long buffer before their first thyroid test
- Re-test later if needed, once they’re past that immune “noise” period
How I Approach Thyroid Testing in My Program
Here’s what works for me as a Welsh Springer breeder:
- First test around one year old — this gives me an initial baseline once the dog is mature and past their early vaccinations. I do this test right before their second rabies vaccination (three-year).
- Test again around two years old — do the test again when they are mature before any breeding plans.
- Avoid testing within 6–12 months of vaccinations to reduce the risk of false positives.
- Submit to OFA — this helps build a public record of health-tested Welsh Springers and supports the breed as a whole.
The Bigger Picture
Thyroid testing isn’t just a box to check—it’s a way to protect the health of our breed. By taking the time to test properly, time it wisely, and share results, we strengthen the future of Welsh Springer Spaniels.
As breeders, we owe it to our dogs and to puppy families to do everything we can to prevent passing along hidden autoimmune issues. And thyroid testing, done thoughtfully, is one of the best tools we have.
Hypothyroidism is well-documented in dogs, and Welsh Springer Spaniels are among the breeds with concern (OFA Thyroid Registry).
- MSU and Hemopet are both respected labs for canine thyroid testing.
- Recommendations about waiting 6–12 months post-vaccination are based on veterinary endocrinology and immunology guidance (e.g., Dr. Jean Dodds, Hemopet).
