It is very common for all dogs to coughon an occasional basis, especially when they first wake up. However, allergic sneezing is typically a nonproductive sneeze that occurs in paroxysms and the infections will often produce puss. If you notice a bloody discharge from a single nostril then that is an indication of a tumor or a foreign object.
Acute Coughing

Although we have discussed the issue of your dog having a persistent and constant coughing problem, acute coughing can be a sign of something a little less dangerous, but important nevertheless. Acute coughing may be a sign of kennel cough, acute bronchitis, inhalation pneumonia, a foreign object in the airway, or even an infection of the tonsils, larynx, or pharynx. Kennel cough is contracted from other dogs which causes inflammation of the voice box. Bronchitis is caused by a bacterial or allergic inflammation to the bronchi in the lungs. And of course any foreign object stuck in the lung will cause acute coughing.

What to do: Kennel cough is extremely contagious so be sure to isolate your dog and get him to the veterinarian right away. Cough suppressants can be given to your dog to ease the pain. Medications an be administered to treat any of the above infections. And if there is only a foreign object stuck, then the vet can pull it out with forceps.

Snoring

There are many breed of dogs that have elongated soft palates that hang at the back of the throat, especially those dogs with compressed faces. This soft palate interferes with the larynx and produces a snore. An allergic inflammation in the throat can also be the cause of your dog's snoring problem. Also, snoring is enhanced if the dog has narrow nostrils and larynx.

What to do: Although snoring may not seem like a series issue, it is always best to consult your vet for a full checkup. And if you have a dog breed such as the Pekingese or Pug that snores, this could be a sign of potential heart and breathing problems. Your dog may have surgical reduction of the length of the soft palate to reduce or eliminate the snoring issue.

Changing Of Your Dog's Voice

If you notice that your dog's bark is altered in any way, then it could be due to damage of the larynx. Also, allergic reactions from bee stings can cause laryngeal swelling. Worst case scenario for the older dog is that a tumor has developed.

What to do: Your vet may give your dog antihistamines or anti-inflammatories to reduce allergic swelling. If the problem is as severe as a tumors, then your dog will undergo surgery to have the tumor removed. If you suspect your dog of having any of the above problems then the vest may have to insert an artificial windpipe, administer medications, or at worst, surgery. Improvement to cardiac function controls heart related coughing.