Ok, so I had a client call with a dog she purchased from me on full registration that had two litters, and now claims the bitch has a thyroid problem. Low thyroid. Is this genetic? I've never ever had this in my lines.

She wants her money back because she says she got full registration but now "she can't breed the dog". I'm like, "you had two litters!" I understand the disappointment. I never guarantee a dog is "breed able", but heck, she had 2 litters. I'd be happy with two litters out of a fantastic bitch.

This is a new one from me. Do I blame the parents? Fluke? Anything nutritional? Environmental?

I'm so upset I'm not thinking clearly, so I need someone to help me think through this logically and know how to answer this person. She's somewhat of a hothead too :(

Anyway…any help or insight would be greatly appreciated.

Please, no flames, I'm really asking for help, advice.

I think if you contact Dr. Jean Dodds you will find that a majority of Labradors, if tested(for whatever reason), have a lower than normal thyroid(so do some sighthounds). If her bitch was showing clinical signs of thyroid issues, that is more or a sit and up take notice. Thyroid is affected by autoimmune issues so something often is breaking down or has been attacked to cause either case of of hypo or hyper. You also need to know how extensively where the blood tests run. A full complete out of clinic test on thyroid could easily run a few hundred dollars. The snap tests in clinic are not enough, Dr. Dodds will tell you that.
Anyway, phone and talk your client off the roof so to speak, ask for photocopies of the lab results and educate yourself more fully on the situation and on thyroid disease. Chances are if the bitch was not exhibiting classic clinical symptoms, it is just a low thyroid and carry on. I will tell you, if it was major, chances are her bitch would have never conceived and produced a litter.
One of the first thing to get thrown offline with thyroid is reproduction.
Myself I can't guarantee to replace against autoimmune related issues...I mean, some of those issues are environmentally influenced or diet and once puppy leaves my home, despite my recommendations, I have no control over how they manage either dogs environment, health, inoculating etc etc
I am not a vet either, just an experience dog breeder...phone your own vet and discuss this with them also.

I learned the same thing. Low thyroid results are normal in Labrador Retrievers.

That aside, you do not owe her anything. Remember Nancy Reagan? Just say NO. You do not need to debate anything with her.

From http://pets.webmd.com/dogs/hypothyroidism-in-dogs

Hypothyroidism in Dogs

This is a disease of thyroid deficiency. The thyroid gland sits on the throat below the larynx. Its function is to produce the hormones thyroxine (T4) and triiodothyronine (T3), which control the rate of metabolism. Thus, dogs with hypothyroidism have metabolic rates below normal. Hypothyroidism, in most cases, is caused by autoimmune thyroiditis (also called lymphocytic thyroiditis), which results in destruction of thyroid tissue. AUTOIMMUNE THYROIDITIS IS KNOWN TO BE AN INHERITED DISEASE. Idiopathic thyroid gland atrophy is a rare cause of hypothyroidism. The cause of both types of thyroid gland atrophy is unknown, but environmental and dietary factors are possible contributing factors.