Runny nose, coughing, and chihuahua's tend to get runny eyes. These can be signs of allergies too sometimes. It could be one or more. Is there any wheezing or congestion? Can you hear or feel it in the chest? If so, you should see your vet. Cold's by themselves need monitoring and often antibiotics are given for a simple cold to help prevent secondary infection since it can quickly develop into pneumonia (ESPECIALLY in young dogs) which needs treatment and can cause death. Use of vaporizers does seem to add to the comfort level in addition to treatment from your vet. If your dog caught a cold after giving it a bath you should see a vet immediately since they may have inhaled water and that is probably not a cold but aspiration pneumonia.
It's best to visit your vet if you think your dog might have a cold so they can give instructions, maybe some cough medicine for dogs (tracheal damage can result from a lot of coughing) if indicated and to make sure it's a cold and not pnemonia or even if it's just allergies and they can get a weight and give you the proper dosage on some children's benedryl or similar relief. It is best that you don't decide what's wrong and treat for the wrong thing since you may not be right and your pup (and you) could pay the price.
It's best to visit your vet if you think your dog might have a cold so they can give instructions, maybe some cough medicine for dogs (tracheal damage can result from a lot of coughing) if indicated and to make sure it's a cold and not pnemonia or even if it's just allergies and they can get a weight and give you the proper dosage on some children's benedryl or similar relief. It is best that you don't decide what's wrong and treat for the wrong thing since you may not be right and your pup (and you) could pay the price.
