Simply put, a hernia is a rupture. However, that definition is not only simplistic, but it also does not cover the entire gamut of this potentially fatal occurrence. On the other hand, the correct definition becomes difficult to understand. Moreover, when one tries to simplify the meaning of the word, that explanation itself becomes unfathomable. Anyway, let’s try.
A hernia is a protrusion of portion of an organ or tissue through an abnormal opening. It must have a ring around the opening, a sack and contents.
According to where the hernia is located, it will be defined as a Diaphragm Hernia, an Umbilical Hernia, an Inguinal Hernia or a Scrotal Hernia. The latter three cases are readily and easily visible.
Sometimes, as in the case of the Diaphragm Hernia, the hernia is inside the animal’s body, whereby the diaphragm (that strip of muscle which separates the contents of the abdomen from the thoracic cavity containing the lungs and heart) is torn, thusly allowing abdominal content to protrude through the diaphragm into the thoracic cavity. Since this cannot be seen, the first step is to have an X-ray done. The veterinary surgeon will take it from there.

These hernias usually involve the umbilical cord (navel string) which connects the mother dog to the foetus.
These types of hernias may vary in size. Some may contain only fat, while, in other presentations, the protrusion may be filled with portions of the intestines. Your vet will use his/her finger to ascertain how large the hole in the lower part of the abdominal surface is, and whether he/she can easily replace the intestines. In any case, the vet will advise that surgery be performed to seal the hole in the ventral (lower part) surface of the abdomen.
It would be unwise for the caregiver not to agree to have this relatively simple procedure performed on the pup/young adult. If left on its own, the orifice will increase in size, and greater portions of intestines will protrude into the sac, and the ring will constrict and imprison parts of the intestines. The pup would eventually die.
The question is often asked whether the Umbilical Hernia is linked to a genetic origin. The scientific jury seems to still be out on this debate. Having said that, one cannot negate the fact that Umbilical Hernias are often seen in male animals that are born with a condition, whereby one or both testicles are not visible, and do not appear even after weeks/months have elapsed. This ailment is known as Cryptorchidism (hidden testicles). The “genetic” argument seems to hold more sway.
Furthermore, some breeds are known to exhibit the Umbilical Hernia more often than others, again giving credence to the argument supporting the genetic predisposition to the development of hernias in pups and young adults.
Such breeds are: Weimaraners, Pekinese, Basenjis and Airedale Terriers.
It should be noted that, during birthing, the mother dog might sever the umbilical cord too close to the puppy’s abdominal wall, which increases the susceptibility to Umbilical Hernias.

These are seen when abdominal contents protrude into the groin area. This condition is easily visible. Small Inguinal Hernias seem to appear more frequently in male puppies, above the scrotum (the sac in which the testicles reside). My advice is to keep the newborn pup under constant supervision. If the condition does not go away within a week, surgical repair is indicated.

This visible occurrence emerges when abdominal contents protrude into the scrotum (see above paragraph).
The clinical signs of Inguinal and Scrotal Hernias would vary from non-painful swellings to visible distress and vomiting in dogs – especially if portions of the small intestines are strangulated. The good news would be that the trapped intestines could naturally free themselves and the symptoms would disappear. The bad news is that the condition might recur within a week. Surgery would then be necessary to alleviate the condition more permanently.
Finally, allow me to advise that any attempt by the caregiver to place a bandage in the herniated areas will not yield great success. Many of the above-mentioned hernias may correct themselves and disappear within 4-6 months. My “rule of thumb” is simply this: if the caregiver/vet can push his/her little finger through the ring and the aperture increases in size, then perform the surgery. Actually, if it is a female pup, scheduled to be spayed within a few months, one might (after discussion with the vet) opt to wait and carry out both surgical interventions (correction of the hernia and spay) at the same time.