Experienced and professional animal trainer provide their insights in answering this question :
A. He/she may have problems with spine or painful hips. I would suggest you to take her/him to your local vets to find out what is the problem.

How to Identify Common Pet Problems ?

Our sources include academic articles, blog posts, and personal essays from experienced pet care professionals :

Pain or Illness

Shivering could be a sign that your dog is in pain or suffering from an illness. Shivering and muscle tremors can be symptoms of serious conditions such as distemper, hypoglycemia, Addison`s disease and inflammatory brain disease, as well as more common ailments like an upset stomach.

Just like humans, dogs can shake or tremble with fear — but there are several other reasons why your dog might be shaking. Shaking can be a sign that your dog is in pain, has low blood sugar, or has a medical condition like neurological disease.
Many dogs develop tremors as they age. This is often due to their muscles weakening as they get older. It could also be a result of their nervous system deteriorating. If your older dog suddenly develops a tremor, be sure to take them in for a check-up with your vet.
If your dog is lethargic and shaking, it is most commonly a sign of pain. You may not know where the pain is, but it`s a sign that your dog is in distress and is not feeling well. Sometimes the dog isn`t sure what is going on either and is trying to move as little as possible so they don`t hurt as much.
This can happen due to mobility-reducing health conditions, surgery recovery, or lack of use in aging. Arthritis in your dog`s back legs may cause the muscle in your dog`s legs to atrophy. Not so coincidentally, arthritis is another condition that could cause your dog`s legs to become shaky and weak.
Some signs of a stroke in dogs include a head tilt, circling, loss of balance, and unusual eye movements. If you think that your dog is having a stroke, don`t delay getting them to the vet for diagnosis and treatment. Treatment is mostly supportive, and it`s important to treat any underlying causes.
Anxiety and fear

For senior dogs, problems like vision loss due to cataracts and hearing loss can alter their confidence and personality and make them more likely to tremble. It is common for some dogs to shake out of fear or anxiety. For example, some dogs tremble during thunderstorms.

Pain tremors in older dogs may result from age-related health conditions like osteoarthritis, which is inflammation of the joints caused by cartilage degeneration. Hip dysplasia is another possible reason for back leg shaking.
Old age. Sometimes dog trembling is due to old age. It`s not unusual for this to occur as they get older, however sometimes too much shaking could be a sign of pain and in particular joint pain. If this is the case, take them to the vet as soon as possible and they will be able to suggest how best to help your dog.
Shaking is normal behavior for Dachshunds, but some cases would make worrying about your tiny long darling reasonable. If your Dachshund shakes, it`s most likely harmless and due to something like excitement, too much excess energy, attention-seeking, or cold.
Shaking limbs can signify neural distress, poisoning, kidney failure, distemper, pain, or weakness. You must speak with your veterinarian or neurologist right away.
According to multiple sources, shaky legs can indicate kidney disease, dehydration (perhaps related to kidney disease), trauma, toxicity, a side effect of a medication, hypoglycemia, inflammation, or even a nervous system disease.
Limb shaking TIAs are a rare form of TIAs that present as involuntary movements and often confused with focal motor seizures. [1–6] This distinction, however, is crucial as this form of TIA is often an indicator of severe carotid occlusive disease and patients are at high risk of future stroke.
In the case of a stroke, your pet`s brain sends incorrect signals to their body. For example, your pet may not be able to respond to your spoken directions. Instead, he may move in a directionless fashion and seem to be walking in circles. He may appear as though he is drunk and be unable to walk in a straight line.
The only way to diagnose a stroke is with an MRI of the brain,” Dr. Singler explains. If your pup has a seizure or any sudden changes in their alertness, mobility, balance or behavior, take them to the vet`s office as soon as possible.
Some toxins cause reactions right away, while others cause symptoms several hours or days later. For instance, the first symptoms of antifreeze poisoning can appear in as little as 30 minutes, whereas the symptoms of chocolate poisoning take between 6 and 12 hours to show up.
Symptoms can include collapsing, jerking, stiffening, muscle twitching, loss of consciousness, drooling, chomping, tongue chewing, or foaming at the mouth. Dogs can fall to the side and make paddling motions with their legs. They sometimes poop or pee during the seizure.
Acute pancreatitis can occur after a dog eats a fatty food such as pork, beef, and some other human foods. Dogs that get into garbage can develop pancreatitis. Pancreatitis can also have other causes, including certain medications and some viral or bacterial infections.
Dog pancreatitis shaking

Sometimes dogs with pancreatitis may shake due to abdominal pain, this may also be paired with a very bloated or tense abdomen. If you notice these symptoms, take your dog to the vet as soon as possible for treatment.

Toy breeds, in particular, tend to shake and tremble more than other types of dogs; this especially happens with Chihuahuas. “This can be due to their small size, so they tend to feel colder than larger dogs do, and this can cause them to shiver,” explains Dr. Barrack.
At this age, dogs can benefit greatly from regular exercise, but you may notice that yours is becoming mellower. She may start to sleep more often and might respond to commands more slowly, or just take a little longer to spring into action than she did just a few years ago.
It`s important never to give paracetamol to your dog unless your vet tells you to – it can be very dangerous if it`s given incorrectly.” Claire explains that you should always head to your vet for advice, including if your pup accidentally digests a painkiller.
What is shaker syndrome in dogs? Shaker syndrome is a condition involving generalized head and body tremors in dogs. Other names for this condition include steroid-responsive tremors, generalized tremor syndrome, or idiopathic (cause unknown) tremor syndrome.
Sudden onset of collapse can be secondary to a variety of disorders including spinal cord injury, orthopedic disease, or systemic illness. This sudden hind-leg weakness may be a sign of a disease that requires prompt attention from your regular veterinarian. Or even a trip to the emergency room.

Relevant Questions and Answers :

the most relevant questions and answers related to your specific issue

Q. How can I train my 4 month old puppy to sit?
ANSWER : A. Training basic commands such as sit is very easy using a positive reinforcement method and does not require any more materials than a place to sit and some very yummy treats! When beginning to teach your dog new tricks, starting off in a distraction free area (such as a quiet room in the house) is best. The training can then expand to more distracting places once your dog has the hang of things.

Start by showing your dog a tasty treat and placing it over his or her nose. When they begin to sniff at the treat, gently move the treat backward. Most dogs will follow the treat with their head, and the backward motion will cause their back ends to sit down! Once your dog sits, reward with the treat and some praise. If your dog tends to walk backwards instead of sit, doing this technique against a wall will prevent your dog from walking backward and encourage sitting.

Once your dog has done this a few times, begin to add the word “sit” every time you put the treat above your dog’s head. Only say the word once, and then continue with the luring motion. Your dog will begin to associate the word with the action after several tries! After this, you can begin to attempt to offer the word “sit” once, and if your dog does so, reward with a treat and praise! If your dog forgets, or appears bored, stop training and try again at a later time- most puppies only have an attention span of a few minutes at most!

Q. My 9 year old mini Doxie is shivering off and on can walk but appears to be having trouble going from sitting/laying to standing?
ANSWER : A. He/she may have problems with spine or painful hips. I would suggest you to take her/him to your local vets to find out what is the problem.

Q. My puppy refuses to walk outside on the leash. This only happens when we’re outside… Is it stubbornness or fear?
ANSWER : A. It is never stubbornness. Dogs are not stubborn, they can’t be. Dogs do not generalize well, and dogs display fearful behavior that appears to be stubbornness. Absolutely NEVER force this dog to walk outside when he is uncomfortable with doing so.. the more you force him to do it, opposition reflex – the more he will resist. The more he resists and is forced into it, the less he learns about being comfortable, and the more he becomes fearful of you and of the situation.

What you can do is carry extremely high value treats outside with you. Things like cooked white meat chicken, cooked fish, turkey pepperoni, turkey bacon, diced ham, mozzarella cheese sticks – all cut up into tiny little pea-sized pieces. You can also use peanut butter in a squeeze tube. First, put on the leash indoors and begin feeding him the treats. Help him make positive associations with having the leash put on. Then, take the leash off, and start over in 10min. Put the leash on, feed treats, walk to the door, open the door, feed treats, close door, take off leash. Start over in 10min. Put on leash, feed treats, go to door, feed treats, open door, feed treats, go outside, feed tons of treats and praise. Keep Titus in his comfort zone. If he doesn’t want to go far, just feed him tons of treats where he IS comfortable going. Make sure everything is calm/happy/positive. I bet in a week of doing this, he will be happy with walk further and further all of the time. If ever he is uncomfortable, feed him lots of treats for being a brave boy, and then turn around and go back home. It’s all about keeping him in his comfort zone.. it’s all about remaining within his threshold and never forcing him to feed uncomfortable.

This is very common for puppies. The world is scary! It’s brand new to them, and it’s up to you to make their interactions and discoveries positive, happy, calm, and to never force them into anything.

Q. I have a 13 1/2 year old Shih Tzu. How old is he in dog years?
ANSWER : A. It’s used to be that dog years were 7 years to every 1. Now it normally around 5 years to every year as long as your dog is healthy and kept up with vaccines. So he’s about 68ish in dog years.

Read Full Q/A … : Shih Tzu Age

Q. Does an indoor cat need to be vaccinated every year?
ANSWER : A. In practice, I recommend a feline combo vaccine every year, but will generally start administering every 3 years once they have had their kitten vaccines and 2 additional yearly vaccines. Rabies, is required yearly by law, and if kept up to date can be good for up to three years also. Based on the age of your cat I would give a yearly feline combo and rabies, and then boost the combo again next year.

Q. My 1 year old great Pyrenees will not walk on the leash she stops and jumps around on the leash and when I try to walk her she just sits down.
ANSWER : A. At one year, she is right in the middle of canine adolescence which is when new fears can show up. She needs positive reinforcement and luring to teach her leash walking is a good thing. You can take some special, tasty treats that she doesn’t get regularly for leash walking time only. Use these treats to lure her forward a little bit at a time. Don’t pull or force her or it will become a big, negative experience to only reinforce her discomfort. Keep it light, positive, and fun. You will likely only get a short distance the first few days, but within a few weeks you should be able to increase that and help her overcome her fear about it.

Q. What to do about dogs who lose all their housebroken-ness in the winter because they don’t want to go out.
ANSWER : A. See a vet to rule out medical causes such as UTIs. Reinforce crate training (again if necessary). The crate should only be big enough to stand, turn around and lay down. They go out FIRST thing in the morning. Pick a spot outside and wait. No walks until they go. Praise and rewards should be given immediately afterwards. Once inside, they go back in the crate or on a leash on your hip so you can watch for cues to go. Take up the water 2 hours before bedtime and take them out right before bedtime. Be patient. Be consistent.

Q. What can I do to help our Lab stop pulling on the leash when we go for a walk? I have tried different techniques but after 2 1/2 years she still pulls
ANSWER : A. POST TWO:
In the mean-time, while you’re working on building up that attention indoors, you should be using a front hooking harness outdoors on your walks. This will eliminate your girls pulling power. The Sensible http://www.softouchconcepts.com/index.php/product-53/sense-ible-harness and the Sensation http://www.softouchconcepts.com/index.php/product-53/sense-ation-harness harness are the best front hooking harnesses on the market because they do not have the martingale loop on the front of the harness (which can cause the dog to yo-yo during walks).

Lastly, I’d just like to add that dogs sniff the ground during walks for added mental stimulation. If your dog isn’t allowed to sniff the ground, the walk isn’t nearly as fun or tiring. When you are practicing attention on your walks, make sure it’s in short, small bursts. Attention for a few steps, back to sniffing for several steps, attention for a few steps, sniffing for a few minutes.. etc.