It sounds like your dog might have either kennel cough
or canine influenza
Both of these are very easily picked up from another dog.
You can, if you think this is the problem see if some Robitussin DM will help the dog breathe better and control any cough or sneezing or runny nose. Read here about cautions and dose info
You can see and hear a dog with kennel cough here
If you see a colored discharge from nose or eyes, if your dog coughs stuff up, seems lethargic, has any real trouble with breathing, or goes off eating, see your vet as your pet may have a secondary bacterial infection that will need antibiotics or other meds.
If your dog has not been on heartworm prevention a heartworm infection can cause this sort of coughing.
Some breeds of dogs including this one can have problems with their trachea which you can read about here
which can also cause coughing.
Hope this helps you!
They have likely been exposed and if they are going to get it may be incubating it.
But dogs all have different immune systems so one dog might get really ill and another seem hardly ill at all with these upper respiratory issues. I'm sure you know people who get really ill when they get a cold and others who barely seem sick and its the same with dogs and their upper respiratory viruses.
Kennel cough is passed around by airborne droplets from sneezing etc. Its easy for a kennel full of dogs to get it and pass it along but any dog can pass it to any other dog no kenneling required.
If you live in an area where heartworm is a problem then they should be tested and put on prevention. It is far cheaper to do prevention than to try to treat heartworm. You can read about heartworm here
If cash flow is an issue, check with your local humane society to see if there is local low cost vet care, ask your vet if you can do time payments or here are some groups that might help you afford the vet bills:American Animal Hospital Associationhttp://www.aahahelpingpets.org/" Through the AAHA Helping Pets Fund, veterinary care is possible for sick or injured pets even if they have been abandoned or if their owner is experiencing financial hardship."Angels 4 Animalshttp://www.angels4animals.org/"Our services range from financial aid to complete treatmentto those pets and pet owners in need."Care Credithttp://www.carecredit.com/A credit card company for health care, including veterinary care."With a comprehensive range of plan options, fortreatment or procedure fees from $1 to over $25,000, we offer a planand a low monthly payment to fit comfortably into almost everybudget." They have a zero interest program if you pay within a certain time frame and they list the vets who work with their product.God's Creatures Ministryhttp://www.all-creatures.org/gcm/help-cf.html"This fund helps pay for veterinarian bills for those who need help."Help-A-Pethttp://www.help-a-pet.org/home.html http://www.help-a-pet.org/"Our efforts focus on serving the elderly, the disabled, and theworking poor."IMOMhttp://www.imom.org/"We are dedicated to insure that nocompanion animal has to be euthanized simply because their caretakeris financially challenged."The Pet Fundhttp://thepetfund.com/"The Pet Fund is a registered 501(c)3 nonprofit association thatprovides financial assistance to owners of domestic animals who needurgent veterinary care."United Animal Nationshttp://www.uan.org/lifeline/index.html"The m ission of LifeLine is to help homeless or recently rescuedanimals suffering from life-threatening conditions that requirespecific and immediate emergency veterinary care. We strive to serveGood Samaritans and rescue groups who take in sick or injuredanimals. In certain cases, LifeLine can also assist senior citizensand low-income families pay for immediate emergency veterinary care." They also keep a list of local and national help resources herehttp://www.uan.org/index.cfm?navid=163