Drastic change in 1 year old Sheltie

Question
QUESTION: My 14 month old sheltie has been a playful, active, loving and healthy dog until this morning. His normal food has always been dry kibble with fresh additives such as eggs, meat, brown rice and veggies.  This morning I mixed his dry kibble with a small amount of a new canned food he has never had before by Merrick, called Thanksgiving Day Dinner.  Approximately 1/2 hour after eating he began to run around my house in a circle (house is laid out that way) and continued to do so for 1.5 hours.  He did not want to go for his normal walk with the other dog or play with his toys, just continued to do laps around the house.  I took him to a vet (not his regular one she was not available right away) fearing some sort of allergic reaction.  He checked vitals, such as temp, heart rate, pulse, reflexes, etc. and could find nothing wrong.  The dog still seems very agitated and not his usual self.  Please advise and any help is greatly appreciated.

ANSWER: This appears to be food related. THROW OUT whatever items you added to his diet.  The veterinarian should have offered you some short term drug therapy, such as phenobarbital, to treat this apparently neurological response to (most likely) an additive in the food.  Be very careful what you feed this dog.  Keep him on the diet to which he is accustomed.  Observe him closely over the next few weeks.  The behavior is most likely food related but it might represent an underlying seizure disorder.  Seizures do not always demonstrate as grand mal...shaking, salivating, etc.  Obsessive circling, inability to self-calm, abnormal staring, etc., can all be indications of seizure disorder.  Sometimes seizures appear suddenly (and this is about the right age) and never appear again.  There are medications to control seizures which appear often.

---------- FOLLOW-UP ----------

QUESTION: Thank you for your response.  I did throw out the remaining food and will return all others by that manufacturer.  I was able to contact his regular vet later in the day and she said it might be colic (gas) but couldn't be sure without seeing him.  She said the food might be too rich for him, which makes sense as I have had him on a very good dry kibble mixed with homecooked protein, veggies and a little brown rice, with no problems previously, whatsoever!  I have never heard of colic in a dog this old, only young puppies.  I have also done research and have found Shelties are prone to a Thyroid condition. He is not overweight or lethargic by any means. Should I have him tested for this?  Thank you again, he is fine today and was back to his normal self about 7-8 hours after he ate the food.  He wouldn't eat yesterday, but was back on regular diet and feeding time today.

Answer
Well it's obviously the food!  Since he appears to have gone back to normal behavior, keep him on the diet you already established for him.  I doubt it was "colic" as that takes several hours to develop; however, systemic allergic response can begin immediately upon ingestion (as witnessed by anyone with peanut or shell fish allergy).  Oddly, many food related allergic responses in dogs demonstrate visibly in changed behavior!  Make sure you never introduce into his diet any artificial ingredients and additives (most likely the cause) found in that food you  purchased.  Your sheltie is most likely not suffering from any thyroid disorder UNLESS it was inherited (in the line).  A blood test can't hurt, but I doubt that's the problem.