Several others have suggested keeping a detailed accounting of the cost associated with maintaining the horses during the proceedings. In many states a spouse gets credit for maintaining the marital property (the horses, a house, etc.) during the course of the proceedings. In your case the value of maintaining several horses for such a length of time may very well far exceed the value of the horses.
Finally, G is right about the law firm. You may not be entitled to the actual law firm and valuing it is problematic under any state's laws. However, you should be entitled to a portion of the value of attributed to it. For example, if it is valued at $200,000, then your husband should be required to give up $100,000 of marital assets in exchange for the value he is keeping in the law firm. Getting it appraised early is important and your husband will not be happy about that!
Good luck! It is a long and stressful process for anyone involved. There has been some great advice on here and some absolutely horrible advice. Your best course is to do everything completely above board and follow your lawyer's advice. Good records help you attorney immensely. It does not hurt to meet with more than one attorney if you don't have a good feeling or click with the first attorney you speak with.
P.S. Not all judges are as awful some may think