My dog has become lazy since we put a tick collar on him. He had ticks and has had a tick bath, through out his bedding and sprayed the house.

You might be slowly poisoning him, so that he isn't lazy at all but suffering from chemical poisoning.

Is he an outside-only dog? Chained to a stake or tree maybe?

He only goes outside for potty walks and usually runs home. Today we went for his potty walk and he walked home slowly. He's been lying around all day. I just took off his tick collar to see if there's a change in him.

If there is ever a major change in my child or pet, I make a doctor/vet appointment to find out what is going on. I also do a lot of thinking about the environment, changes in routine, others' behavior changes, etc.

If he was covered in ticks, I would think a tick born illness...

OH, and I failed to mention...

Flea and tick collars are about as worthless as they come. They only repel fleas and ticks from around the neck area.

For future reference, either give him a flea & tick bath, which is suppose to last about a month, or get the topical treatment, this also lasts about a month. You don't need to go over board and give him a bath and apply a repellent. Its one or the other. Not both.