for people who love the littlest dairy goats
I am so sorry that this happened. I know it must have been devastating. Without knowing the approximate gestation of the kids (and a big ole' list of other questions,) it is a little harder answer, but I am going to explore a few possibilities here, which will give you a start toward some research =)
I think the 3 main reasons to consider are 1) the dewormer, 2) a nutritional deficiency, 3) a disease that the goat may be carrying
1) That was a pretty large arsenal of dewormers that you gave, so I am curious why you administered all of that? That type of dosing is typically done when you know that you have a resistance on your farm and the goat is in pretty bad shape. The Valbazen and Safeguard are actually the same class, with Valbazen being the much stronger of the 2. Valbazen is also a dewormer that most do not give pregnant goats because it can cause abortion, especially if given in the earlier part of a pregnancy. For this reason, most completely avoid using it in pregnant goats.
2)Nutritional deficiency- Selenium being the big culprit here, but copper, manganese, and iodine deficiency may also play a role in premature/still births. It sounds like you have a pretty well balanced diet and also like your other doe has done just fine, so perhaps not top of the list. I would check the age of your minerals to be sure that the bag has not gotten too old. Also- sometimes free choice minerals are not enough and additional copper and or selenium supplements may be needed. If you have well water that is high in sulfur, for instance, that competes with copper absorption. A best way to get a look at mineral balance within your herd, is to submit a liver from a deceased/processed goat for testing, so keep this in mind for future reference.
3)A disease that the goat is carrying- there are a variety of infectious causes of abortion. Chlamydia, Q Fever, Brucellosis to name a few. Unfortunately, the best way to diagnose the majority of infectious causes is by submitting the aborted fetus and the afterbirth for testing. You said that this doe is 4- have you had her since a kid, or did you recently get her? If you recently got her, did she come from the same place as the doe with healthy kids?
I am going to post a few articles/podcasts below for you to do some further research.
I would also like to suggest that you may want to consider housing your buck in a separate area from your does. He will need another buck or a wether as a buddy. The problems with keeping ND bucks and does together are many, but one of the top, along with getting very young doelings pregnant when they are much too small, is that you do not know when the due dates are. This can lead to frustrating situations like you have here, because you are left with so many questions surrounding this early birth. In addition, you can avoid kids being born out in the pasture during a very cold winter day or one drowning in a sack that needs to be popped and removed after birth, because mama is so busy with baby #1 that she didn't even notice baby#2 came out.
I sure hope this gives you a start in trying to answer your question here
Ditto on everything Tammy said.
I also am curious about how long you've had this doe and how long she has been with the buck. If she's been with him for very long, I would definitely be thinking about a nutritional deficiency because typically they get pregnant within three weeks of being put in with a buck. Since five months ago was May, that's off-season, and not all NDs breed off-season. But if she's been with him since last fall or even January, then I would definitely be looking at some kind of nutritional deficiency because she should have kidded in spring or early summer.
If you only recently got her, then she could have come to you mineral deficient. Did the other doe come from a different herd? Being a 4-year-old first freshener is never easy, and it could indicate some type of problem.
It is possible to have a goat give birth to healthy kids when you have some issues with mineral deficiencies. Back when we had copper deficiency so bad that 1/3 of our does were not even getting pregnant, some did get pregnant and had what appeared to our untrained eyes as healthy. But we were totally new, so we could have been overlooking things that would be obviously problematic to me now after 19 years. How old are the kids, and what do they weigh?