Llamas are valuable guard animals. Llamas bond with the herd they are charged with protecting and will chase off bobcats, coyotes and other predators of sheep, goats and alpacas.

That said, llamas have virtually no defense against a pack of predators. Most notable, as a threat to llamas, and many other valuable livestock, packs of stray dogs.
A good fence certainly helps. A vigilant local SPCA group is an other critical resource. And, in my mind, a truly great guard dog is also essential.
I am not talking about a loyal family dog but, a true working guard dog. Most often used is the Great Pyranees. These are fine animals but, I personally prefer the Tibetan Mastiff.

I have had a Tibetan Mastiff with my herd for 12 years now. Like the Great Pyranees, these are gentle giants, noted for large size, loud bark and ability to bond with their herd.
Since we only breed llamas at the ranch, all dogs and cats at the ranch are spayed or neutered. My first mastiff was a female, Nymh. What a great animal. She lived 10 years and was a quiet, gentle friend to me and my family. At the same time she was vigilant and dedicated to protecting the llamas.
Nymh slept most of the day in a shady area where she could see the herd. At night Nymh roamed the pastures where the llamas slept or took position on high ground where she had a better field of vision.
When Nymh began to age, I bought Bhoo, as a newly weaned puppy, to learn the ropes from Nymh.

It does take time for ‘puppy’ to wear off and guard dog instincts to kick into high gear. This process takes roughly 2 years. So, by the time Bhoo was ready to take over as guard master, Nymh was very old for a large dog. She then semi-retired and just worked at protecting me.
While I do highly recommend guard dogs, these animals bark a lot at night. Sort of a warning to the coyotes and bobcats to stay away.

They also intimidate by their size and aggressive stance. So, if you are in an area with neighbors near by or you really find barking at night annoying, this is not the breed for you. But, if your farm is more isolated or you have a lot of pastures, these animals will really be a help to you.
I have learned that there are about 2 weeks every summer when I spend the build of my time brushing out the winter coat. I get enough off to knit another medium sized dog. Some folks shear the hair off of their Pyranees in the summer for this same reason and I did do that once to Nymh. So you can go either way. It is important though, in a hot climate, to help get that winter coat off so the animal will not stress in the extreme Texas summer heat.

