The short answer
The label says 12 weeks and up. It says nothing about pregnancy. Ask your vet first.
We found no safety study of ThunderBites in pregnant or nursing dogs. "12 weeks and up" does not mean "safe in pregnancy." Your vet may tell you to wait until the puppies are weaned. That is often the safer call.
Original10 mcg melatonin, 15 mg L-tryptophan, 50 mg chamomile, 25 mg thiamine per chew
- Dose by weight
- Up to 26 lb: 1 · 27–50 lb: 2 · 51–99 lb: 4 · 100+ lb: 6
- How to use
- As needed, 30 min before the stressor
HempSame actives as Original plus 75 mg hemp seed oil and 75 mg hemp seed powder (not CBD)
- Dose by weight
- Up to 26 lb: 1 · 27–50 lb: 2 · 51–99 lb: 4 · 100+ lb: 6
- How to use
- As needed, 30 min before the stressor
Calm + Probiotic1.5 mg melatonin, 30 mg L-theanine, 150 mg ashwagandha, 3 billion CFU per chew
- Dose by weight
- Up to 25 lb: 1 · 26–50 lb: 2 · 51–75 lb: 3 · 76–100 lb: 4
- How to use
- Daily, every day
From ThunderWorks labels (actives listed per 2 chews, shown here per chew). Ask your vet before giving Calm + Probiotic to small dogs, puppies, pregnant dogs or dogs on medication.
Why pregnancy calls for extra caution
Pregnancy changes the picture for most supplements. An ingredient a healthy adult dog handles well can still affect the puppies. It can also pass into milk. Supplements do not have to be tested in pregnant dogs. So "no reported problems" usually means "not studied." It does not mean "proven safe." With little data, vets lean careful. That goes double for a chew with 7 actives, since each one would need to be cleared.
Which ingredients raise the most concern
ThunderBites Calm + Probiotic combines several calming actives — ashwagandha, L-theanine, L-tryptophan, melatonin, and thiamine (B1), plus ginger and chamomile — alongside probiotics (3 billion CFU per chew; 6 billion per 2 chews). Three of those actives are the ones most often flagged for pregnancy:
| Ingredient | Role in the chew | Pregnancy concern | Takeaway |
|---|---|---|---|
| Ashwagandha | Adaptogen, stress support | Commonly cautioned against in pregnancy; associated with a possible risk of miscarriage | The single biggest reason to hold off without a vet's sign-off |
| Melatonin | Sleep and calming support (1.5 mg per chew, a meaningful dose) | Generally advised against in pregnant or nursing dogs except under vet supervision; has been linked to effects on fertility | Use only if your vet specifically approves it |
| L-tryptophan | Amino-acid precursor to serotonin | Recommended only under direct veterinary supervision during pregnancy | Not a do-it-yourself ingredient in pregnancy |
| L-theanine, thiamine, ginger, chamomile, probiotics | Calming, B-vitamin, digestive and gut support | Less specific pregnancy data available | Still worth your vet reviewing on the full label |
The original ThunderBites Calming Chews carry far less melatonin (10 mcg per chew) but still contain L-tryptophan, passion flower and ginger, so the same ask-your-vet rule applies. This does not mean ThunderBites is risky for most adult dogs. A pregnant or nursing dog is a different case. The ingredients above are why a simple "yes, it's safe" would be wrong.
Related: -ThunderBites probiotic vs regular calming chews which better
What to do before giving anything
Bring the ingredient list to your vet, or read it to them by phone. They will weigh it against how far along she is and her health. They may say wait until weaning. They may approve one ingredient at a set dose. Or they may suggest something else. For reference, the standard Calm + Probiotic label dosing is by weight, and it is written for general (non-pregnant) dogs:
| Dog weight | Label chews per day |
|---|---|
| Up to 25 lb | 1 chew |
| 26–50 lb | 2 chews |
| 51–75 lb | 3 chews |
| 76–100 lb | 4 chews |
That chart is for dogs in general. It is not a pregnancy dose. "Made in the USA" and "natural ingredients" are quality claims. They are not proof of safety in pregnancy.
Safer ways to settle a stressed pregnant dog
If anxiety is what prompted you to look at calming chews, most of the highest-value moves are non-drug and vet-friendly. Give her a quiet, low-traffic whelping area away from household commotion. Keep a predictable daily routine and gentle, stage-appropriate exercise. Reduce noise, visitors, and sudden changes. Pheromone diffusers are widely used and generally considered low-risk. If her stress is severe, ask your vet what is safe in pregnancy. That is a safer path than an untested supplement. Call the vet before you open the chew jar.
Related: -ThunderBites chews for small breed dogs with anxiety