I'm not sure why you didn't receive the response I sent to you. I'll send it again in hopes that you'll receive it this time. My apologies if there are site issues about which I'm unaware:((( Deb
Thanks for the answers to my questions.
That's great that he's otherwise not acting ill aside from the coughing he's doing and the change to his bark.
It sounds as if he may have laryngitis
Acute laryngitis is more commonly seen in cats than dogs but they can certainly develop the problem as well...usually secondary to excessive barking for the majority of patients. However, having said that, there are other conditions which might cause a change in a dog's bark such as infection (usually an upper respiratory infection), aspiration of food or exposure to irritating vapors or trauma.
Since he's been coughing, I suspect that this is why his voice has changed...there's irritation to the back of his throat. And, I suspect that he might have an upper respiratory infection since its' the most common cause of coughing in an otherwise healthy dog.
I don't tend to treat the mild cases of laryngitis with medication although I do suggest that owners feed canned food or dry food soaked in water for 15-20 minutes so that the throat is not further irritated.
In most cases, the voice will return to normal within a week or less or once they stop coughing (if this is why the laryngitis developed in the first place).
As to what you can do for his cough, if he has kennel cough (which is secondary to either a virus or bacterial infection), then he might continue to cough for another week or so until it's run it's course. If this is bacterial in nature, then he'd respond to antibiotics fairly quickly; he wouldn't if this is viral in origin.
As to over the counter treatment options, cough suppressants can be given although I'm often hesitant to use them if kennel cough is the problem. I want those secretions removed from the upper airways and I rarely want to inhibit this reflex.
But acceptable ones to use include Dextromethorphan http://www.petplace.com/article/drug-library/library/over-the-counter/dextromethorphan-robitussin-dm
The dose would be 0.25 to 1 mg/lb 2-3 times a day. You just want to double check labels and ensure that the formulations only contain this ingredient although inclusion of Guaifensin is fine.
If he's continuing to cough for more than 2-3 weeks and/or his bark doesn't return to normal and/or other signs develop, then a vet visit may be prudent.
I hope this helps. Deb