Following my doggy hairball "misadventure" we've been doing a bit of research about them, like you do, here's what we found out:
1. Hairballs are also known as Tricholiths ~ defined as "A calcified intestinal bezoar that contains hair" by The Free Dictionary
or
a Trichobezoar ~ "a bezoar (a mass trapped in the gastrointestinal system) formed from the ingestion of hair." Wikipedia
2. Hairballs are formed by ingested hair that does not pass smoothly through the digestive tract to be eliminated.
3. Dogs get hairballs when they ingest large amounts of hair due to excessive licking or eating prey.
4. Hairballs can get stuck in the dog's esophagus, stomach or small intestine.
5. Symptoms of your dog having a hairball problem include: gagging, vomiting, trying to cough something up, loss of appetite, lethargy, diarrhea, stomach bloating.
6. Preventing hairballs is important as they can make your dog seriously ill, even resulting in death, here's how:
Groom your dog regularly to remove loose hair.
Vacuum regularly to remove hair from your dog's environment.
Make sure your dog is flea free, licking and biting at fleas can result in the ingestion of hairs.
If you suspect your dog has an allergy due to his / her excessive licking consult your vet.
Make sure your dog always has adequate amounts of clean water and that they are drinking enough.
Check that your dog's diet includes beneficial oils containing Omega 3 fatty acids.
Try adding pumpkin to your dog's diet it's full of fibre so can help with the elimination process.
If your dog is licking due to stress try to resolve the stressful situation, if it's due to boredom ensure that your dog has adequate stimulation and isn't left alone for hours on end.
7. If you have any concerns with regard to dog hairballs you should consult a vet as serious ones can be life threatening.