I'm sorry to hear that you're going through this with your dog. I know how scary it can be when your pet appears to be in distress and you can't understand why.
The "covering" of his food is normal. He's' trying to hide it, make it less visible to other "pack" members in case they want to take it. I'll bet if you gave him something to cover the food with, he would - like a paper towel. It's an instinctual action. I've also seen dogs do this with favorite toys and even poop.
As for the episodes, they sound like a panic attack of sorts. You can see shaking and shivering, panting, heart racing - all of this with a panic attack or anxiety-related situation. The question is why are they occurring? Firstly, you have to remember that your dog does not view the world the same way that you and I would. I've seen dogs have panic attacks, episodes of extreme aggression, episodes of intesnse fear stemming from things that you or I would never think of as scary: reflections in windows, particularly at night, reflections in metal dog bowls, ceiling fans, large dark objects (like a person in all black or a large dark colored chair), running water - you name it. So the first thing I would do is I would try to see the world as he does - so we can try to determine if its something in his visual field that's to blame. Look for links in the episodes. Are they occuring at the same time of day? The same room? When a particular person is present? Before or after another particular event? The easiest way to help look for links is to start a dog log. Write down what you see just before, during and after these episodes. Write down who and what's in the room when they occur. And anything else you think may be important. It's much, much easier to figure out triggers when this occurs.
I would also try to think of where you live. Are you near train tracks? Or some other structure that could cause subtle vibrations? Are you in a multi-family home or apartment? Something you're not hearing or feeling could be causing this. So I would think outside the box. Maybe he's feeling vibrations from a nearby highway overpass/bridge or something like that.
Can you tell why he stops his episodes? (i.e. you distract him, or take him for a walk, he just stops for no apparent reason, etc)
When something in the visual field is to blame, you'll often see one of two things: a really intense stare at whatever it is that's scaring them, or complete avoidance of the scary object. So just make note of what he is or is not looking at. Head hiding behaviors or refusing to break eye contact with an area or object are things to look for.
Is this an anxious dog??? Does he get nervous in new, unfamiliar situations? Do certain people make him nervous? Is he prone to fear and anxiety, would you say? If so, I would explore a psychological disorder like anxiety. There are medications that can be helpful for this, so that's something to consider.
I would also videotape the episodes. This will make diagnosis much easier, particularly if something medical is the cause. Showing these episodes to a vet will help them decipher what's occurring and it can give some leads on what areas to investigate further.
In terms of a medical cause, there are some possibilities that it sounds like you've not explored just yet.
One thing that comes to mind is some sort of neurological or pain disorder.
The nerves, which are throughout the body, perceive sensations, like pain, and they transmit these messages along the spinal cord and up to the brain. Some nerves go directly to the brain too. So if you have a problem with one or more nerves, you can get scrambled signals, incorrect interpretations of sensations, and other mishaps. It's possible that a nerve was damaged and the nerve is incorrectly interpreting the signals it receives as pain or some other odd sensation, like tingling, and these messages are firing off at random or due to movement, and they're transmitted to the brain and your dog experiences sensations of pain or tingling, resulting in what you're seeing.
With a back injury, the bones or discs between the bones can temporarily go out of alignment, causing a slight bit of inflammation involving the spinal cord. This can be painful or it can result in odd sensations like tingling and shooting pains. The problem is, antiinflammatory meds would have likely helped with this - although if the problem is more severe, it's possible it just hasn't made enough of a dent in the inflammation.
You also have to remember that pets don't process pain and discomfort in the way that your or I can, so this can really cause anxiety and fear. New and unfamiliar body sensations - even an upset stomach - can also be scary to your pet. Think of it this way: when you or I are sick, we know that we can seek help. We also know that this pain won't last forever - we'll get medication and treatment and eventually, the pain will end. Dogs have no such assurance. So all he knows is that he's in pain or discomfort and for all he knows, this could last forever! Imagine how scary that would be! So you can understand how they can get worked up. And different pets handle pain in different ways - some are more stoic and others have a more outward display.
The other possibliity is that your dog is, in fact, experiencing a seizure. Maybe a chemical that the vet used on your dog is triggering seizures. A dog who is intolerant of a particular chemical could experience seizures (and remember that shampoos and other chemicals can be absorbed through the skin). It's also possible that this is just a coincidence and there's no relation to the visit to the groomer. Since he's had similar incidents in the past, it's possible that he's simply experiencing seizures more often now - it can occur sometimes. There's all sorts of things that can cause seizure - chemical imbalances of the dog's chemistry, toxins, illnesses and infection, injury and even low-blood sugar are among the most common causes of seizure. And in some cases, there's no clear cause for epilepsy - at least no cause that today's medicine and technology can detect.
People typically think of seizures and picture grand mal seizures, which are very dramatic, but only a portion of seizures are like this. There's some more subtle seizure disorders that can affect our pets and a neurologist would be the person to see concerning this. It's also possible that there's something going on with the spinal cord, nerves or brain, in that there could be scrambled signals that are resulting in this spasm. Back injuries can even cause odd events like this. And again, this would be within a neurologist's field of expertise. They can perform all sorts of tests with the brain, nerves and muscles to determine exactly what's going on. These specialists are also more versed in some of the more uncommon disorders affecting pets, as they specialize in a particular body system, whereas your normal vet is likely more of a general practitioner, who is versed in a diagnosis of the more common afflictions affecting our pets.
It's very possible that your dog could be otherwise healthy and still have a seizure disorder. They can also arise seemingly out of nowhere, so even if he has no history, this is a possibility.
Petit mal seizures, for instance, can involve spasms (which could be the case in your dog), episodes of staring off into space and bouts where the dog loses coordination. The mention of these tremors stopping him in his tracks is really consistent with these seizures. What really sets these apart from grand mal seizures is that the dog maintains control over certain parts of the body, so some of these seizures can be very subtle. It's even possible that he's been having really minor episodes for a long time and you just didn't realize it.
Since he's still functioning and in control of his body to some degree (just at an impaired level), it's more likely that he's experiencing petit mal seizures if seizures are the case here, but it's important to get a diagnosis from a vet, as there's all sorts of sub-categories out there when it comes to epilepsy. A veterinary neurologist would be a good place to go from here.
To learn more about canine seizures, you can visit these sites - they have some really helpful information on the different types of seizures and what you can do when these occur. Hopefully, in reading some of the descriptions, something will "click" and make sense for you:
These website links will take you to a site that lists some of the other symptoms of seizure and the different types of seizure: http://www.thepetcenter.com/gen/epilepsy.html http://www.sidyboysfoolin.com/Health/Epilepsy.html http://www.canine-epilepsy.com/FAQ.html http://www.canine-epilepsy-guardian-angels.com/CanineEpil.htm
I'm also going to include some links to sites that list toxic plants food, and household items, as he could be exposed to a toxin that's triggering these episodes. Plus, it's good info to have on-hand just in case. http://www.peteducation.com/article.cfm?cls=2&cat=1939&articleid=1030 http://www.cybercanine.com/toxicplants.htm http://www.peteducation.com/category_summary.cfm?cls=2&cat=1938
I hope this gives you some new directions to investigate with your boy. Don't hesitate to let me know if you have any additional questions. And if you get a chance, I'd love an update on him.
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