Is the transmission leaking or is it blowing out the dipstick tube?

I'd guess that you're getting slippage while towing which is overheating your tranny fluid - you do have an automatic, correct? It could be that the extra-hot fluid is leaking out of a rubber cooler line or past a seal as well.

I would discontinue any further towing until you figure out what is going on. Have you checked your fluid level, color, and smell? If it's burnt, you'll see it AND smell it!

Assuming that your transmission is in perfect condition, as a minimum you would want a supplementary transmission fluid cooler AND a transmission fluid temperature gauge (sensor goes in the pan) if you're going to be towing heavy loads. Keep it out of overdrive as well while towing.

I have a good friend who had a side job towing new camp trailers all over the west coast in his late 90s F250 - toasted his automatic due to failure to heed the advice above. Got ticked off (after getting stranded and then getting stiffed with the tranny rebuild & R&R bill) with it and replaced with a 5-speed manual behind a Cummins in a Dodge dually!

 

Don't know what your bobcat weighs but I know towing mine a one ton is required in kansas.