She’s a 100-lb livestock guardian dog named Gemma, an Anatolian Shepherd/Pyrenees mix, who normally bravely patrols this wooded farm alone in the dark without hesitation. (My other LGD is aging and tends to woof encouragement from his prone position indoors.) Gemma is scared of car rides and trembles the way you do with a big hit of adrenaline, but what I’ve seen twice lately is a whole order higher of violent shaking. Both dogs will run for home over thunder or a gunshot, but I can’t see or hear anything that would send only Gemma leaping into my lap visibly terrified. I suppose she could smell something as scary as a bear or cougar, but would a fear response be that innate over a scent of something she’s never seen? They’re out there but never inside my perimeter fence. My other notion is perhaps more farfetched. As she stood last night with her head in my closet, I watched as a tremor began on her hind leg and then work its way up. I wondered if it was possible that something purely physical or neurological is happening to her and that is scaring her. I’ve had a dog with seizures, this isn’t seizure activity. It’s more violent prolonged shaking than I’ve ever seen, however, and I don’t know if a vet visit is in order. That’s the other thing she’s scared of, so I don’t do that lightly, but I’d appreciate your thoughts.
Really hard to say but I guess it is possible she could be reacting to some kind of internal physical pain that she hasn’t experienced in the past. I would take her to a vet. How long does it last and does she act normal in-between these episodes? Normally guard dogs are not all that spooky of things in the night.
The spasms of shaking last maybe 15 minutes, with me petting and soothing her. She stayed plastered to me all last night, though, which isn’t normal. She seems normal today. You’re right about LGDs not being spooky, normally she’s pretty brave, aggressive actually.
If it repeats a vet visit is in order. My parents had a Malinois that suddenly went hyper-aware and became very fearful, after years of normal behavior. We never found the cause, although she eventually reverted to her old self. Multiple physical causes could also be to blame.
To be honest, my bet would be some form of predator activity, possibly bear. Yes, I would guess the smell alone could set off a fear response.
Wow. 8 posts.
Maybe the dog has IVDD. That made Doxie freak out for a couple days, then, BANG! Crippled!
There is an extensive rehabilitation process you follow, but it seems to work.
Check it out. And post more often. 
My family had a poodle when I was a kid.
I don’t remember it very clearly, but he had epilepsy and would launch himself into your lap and shake like he was freezing when it hit.
I hope your dog is ok, I don’t want to spread doom and gloom. That little guy lived to 13 and never had a problem besides a few spells per year.
Good luck
If your dog doesn’t like going to the vet and car rides, is there a mobile vet in your area that can visit your house? It might be less traumatic for the dog.
I don’t have experience with your particular breed, but I’ve kept large dogs (German shepherds) on my farm in a situation same as yours. My dogs were never nervous about bears. Cougars, that’s another matter.
According to Fish and Game, bears will usually give dogs a wide berth. Cougars will take them for food. Your girl would instinctively understand the danger, especially if she is now mostly alone outdoors without her old companion. We’re lousy with cougars in our state in the rural areas. My game cameras regularly catch photos of them within 100 yards of the house.
My last predator (cougar) loss was a full-grown llama. They’d have no hesitation to take your beloved 100 pound sweetie. I think her fears are justified every time she catches a whiff.
I looked up IVDD and tremors was on the list. She doesn’t have any of the other symptoms but she is about 8 years old with hip dysplasia both sides, so something in the physiological realm could be happening.
Lurking has been habitual. I think I found this board somewhere around 1998, but couldn’t post on a work computer. I’m retired now so I’ll try to speak up more often, okay?
I don’t know the answer, but this sounds like what happens every so often with our Shih tzu. He just had an incident the other night. I can tell, looking at him, something is wrong. He will come to me, my husband or daughter. The trembling, vibrating, I’m not sure what to call it, usually starts in his back leg(s) and progresses up to his head. He has never lost consciousness but does seem a little out of it. From pain or seizing, idk. The vet ran a whole panel of labs and it turns out he’s the healthiest one in the house. I am left to wonder if it’s muscle spasms or a nerve thing. Our other dog does have seizures very infrequently and she goes to her side and foams at the mouth. She’s never gone unconscious, but the Shih tzu other than the shaking, isn’t exhibiting other signs of seizure. It’s very random when they happen, it could be several weeks or several months. I hope everything is ok, poor baby.
My dog#1 (5lb.Yorkie) has a head shaking type tremor on occasion. Vet said it may be due to inbreeding. She is kinda dumb and goofy any way, so it doesn’t affect her life as my lap warmer. We love her like she is. But, with a dog like yours who has a real job, it behooves you to have her checked out. I tend to think it probably is a fear response. Get it checked out.
Keep us posted, and welcome to the non-lurking world. 
Instead of fearfulness I saw pure pain last night so took Gemma to the vet today. X-rays showed a nice looking spine for a dog her size. All the vet could find was some tense muscles along her back. Maybe she strained something. We came home with gabapentin to add to the carprofen for pain that I had on hand. I learned that cougar sightings are more plentiful lately and that these big cats are much less fearful of dogs since hunting them with dogs became illegal. I guess my livestock guardians are going to have to learn a new way of life. Instead of lolling around all day and going on duty at night, I’m keeping them in at night. I don’t have livestock anymore, so no need to risk Gemma all by her lonesome out there.
Dogs, in my experience, are innately afraid of cougars – and so are just about everything else. They don’t need to have any previous exposure. Another thing dogs are afraid of are feral pigs.
My sympathies for your troubles with your dog.
I’m wondering if it could be related to the hip dysplasia. My MIL had a lab that suffered this for the last few years of his life. His personality went from open, loving and playful to quiet, and irritable. He would also frequently display fearful type behavior at seemingly random times, very similar to what you have described.
My AmStaffie had knee surgery two weeks ago and he’s done “the shivers” a few times since (odd this thread was posted at the same time I was wondering why he was doing that). They are just brief episodes.
My dear departed Cooper shook and shivered like crazy when a rattle started buzzing from a bush near our hiking trail. Then the dummy jumped into the brush for a snake vs. Lab showdown. Given your location I’d bet on predator/unknown animal response.
Cooper didn’t get bit but I DID. I instinctively waded into the brush to grab him and got tagged on the hand - a bit of swelling, but mostly a dry bite.
The scent of a predator will reduce many dogs to a shivering blob of jello.
They inherited the same fear response that humans feel. It’s what helped keep us alive and away from predators.
I get that jolt of fear from snakes. It’s deeply rooted and instinctive. Our ancient ancestors knew snakes could kill them.
I watch my dogs on camping trips. Excited barking can mean anything. If they show fear that’s when I get worried and make sure my rifle is close and easy to reach.
Thinking physical disorder. Perhaps epilepsy. I’ve seen that in one dog, where she looked and acted very afraid, and only meds and or the owners soothing would help. Vet visit is needed IMHO.
I am terrified by and deeply interested in venomous snakes. I still can’t believe how strong my dog mom instinct was.
When I saw your location, I thought, easy one, he’s got a Bigfoot in the woods…seriously, I think Ulfrieda and Aspenglow are probably correct, mountain lions are an alpha predator, populations (according to a 2006 study I just saw) are on the rise, and they roam a territory of 50 - 150 square miles…yikes…