Cough syrup is only safe for dogs IF they are not having a productive cough. In other words so long as he is coughing but not brining anything up with the cough. If when he coughs he is bringing up phlegm or mucus you don't want to use a cough syrup or it will suppress the cough and keep the mucusy phlegm in his chest. If he has a dry cough you can try any product with dextromethorphan (DM) in it as the ONLY medicinal ingredient. Make sure whichever cough syrup you choose has DM as the only medicinal ingredient. Many of the other cough syrups contain drugs like ephedrine which can be toxic. My personal choice is Benylin DM. The dose is 1-2 mg of drug per kg of dog. If your dog is 9 lbs then he weighs ~4kg. This means he will need 4-8 mg of drug. You'll probably need to use baby benylin and I would print off my response and take it to a pharmacist to help you find the right volume in mls to give. Also, they should be able to sell you a small dosing syringe to help with accuracy. Remember mg do not equal ml. It's really important not to mess this up as overdoses can be very serious and your dog is very small. Definitely get the pharmacist to give you a hand calculating the dose and to confirm that the product only contains dextromethorphan and nothing else. Good luck and hopefully this information was helpful.