Hello, I'm Dr. Kara. I have over 20 years of experience as a veterinarian and I'd like to help with your concerns about Tanner's twitching, head shaking, and vomiting.
Has he been exposed to any toxins such as flea products or pesticides in the yard?
Is his head tilted?When he tries to walk is he circling?
Does he have rhythmic back and forth or circular eye movement? (like this cat:
Do you feel that he is very nauseous such that he is vomiting or is he reluctant to eat?
Does he have any signs of an ear infection now (ear debris and or redness, itchy ears, head tilt)?
If you know that he has not been exposed to any toxins then from your description of symptoms this sounds very much like vestibular disease.
There can be several causes of vestibular disease. They range from very benign causes such as idiopathic (meaning we don't know the cause but they resolve on their own with supportive care) to middle ear infections or polyps, brain infections(bacterial, fungal or viral or even parasitic), a toxin, or even a primary brain lesion such as a blood clot, bleeding or a tumor.
If we cannot identify a cause then we will often treat the patient symptomatically(anti-nausea drugs, anti-inflammatories and antibiotics) as most dogs do get better with supportive care and treating of the ear infection if present. Prognosis if this is caused by a lesion outside the brain is very good in most cases.
Ideally he would see a veterinarian to look for a cause. A veterinarian will check bloodwork to make sure organ failure is not the cause of his symptoms and scope his ears to look for signs of an infection. If that's not possible then you can try some things at home.
At home you can give Gravol also known as Dramamine (dimenhydranate) to control nausea, which is also used for carsickness. The dose is 4mg to 8mg per pound of body weight every 8 hours. Side effects are mild sleepiness and dry mouth.
Oryou can try Benedryl (diphenhydramine) at 1mg per pound of body weight or one 25mg tablet per 25 pounds of body weight orally every 8 hours. Side effects are sedation and dry mouth as well.
To stimulate his appetite if it is off start a bland diet of 1/3 boiled white skinless chicken, or lean ground beef, all fats and juices drained off mixed with 2/3 boiled, plain white rice. Feed several small meals a day. Add warm water or chicken or beef broth to get fluids in and make it more palatable.
If after a few day's time there is no improvement or he is worse then he needsfurther diagnostics to try and identify the cause. Serious central nervous system (the brain) causes are more likely and thus prognosis is much more guarded.
In a young dog I would be most concerned about a viral infection, such as distemper if he isn't vaccinated, protozoal parasites like neosporum caninum, or toxoplasmosis, or toxins such as pyrethrin or organophosphate based insecticides or some of the newer rodenticides, or low thyroid gland function. Metabolic organ failure (kidney or liver diaease) or electrolyte or mineral imbalances are also possible causes.
If your veterinarian cannot find a cause and he is not improving a referral to a neurologist is best as they can perform advanced testing such as an MRI.Please see this link if you would like to read more about vestibular disease:
Please let me know if you have any further questions.