I'm sorry your dog Buddha is ill. Her symptoms reveal that she has a nervous system disorder which could be related to a problem within or outside of the brain
. I agree because of the sudden onset that toxicity seems most likely. However, because the problem has persisted for a few days, some diagnostics are necessary.
Aside from repeat physical examination, I recommend a full panel of lab work (i.e. 17 assay chemistry, complete blood count with differential, urinalysis and bile acids testing which requires a 12 hour fast). The purpose of the lab work is to look for any lab abnormality that may provide clues about the toxin as well as to check for metabolic causes of neurologic disease (e.g. one example is portosystemic shunt can result in neurologic disease in puppies and bile acids testing screens for that). Rabies is also a cause of neurologic signs and should always be considered in areas with that disease. Testing for rabies in living dogs is never performed.
If the lab work doesn't help identify Buddha's problem, then you will have the option to treat supportivly or go for referral to a veterinary neurologist where they may want to perform MRI and cerebrospinal fluid analysis. Supportive treatment may include fluids to flush Buddha's system as well as keep her well hydrated, meclizine for motion sickness if she has vestibular signs (sounds like she does), nausea medication such as Cerenia as well as anything else your veterinarian deems necessary based on the physical and lab findings.
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