Dog Underbite in Shi Tzu, Pug, and Other Breeds: Causes and Correction Options for Dogs with Underbites

Dog Underbite

Dog underbite may or may not be a dental anomaly, depending on the breed of dog involved. It is commonly more of an aesthetic than a health issue but if necessary, dogs with underbites can benefit from surgery and other orthodontic interventions. In this article, we explore more about underbites in dogs, including problems associated with the problem, and remedial measures typically applied to correct it.

What is Dog Underbite

Bulldog with Underbite
Picture of a bulldog with an underbite, a common genetic trait in the breed.

The term underbite refers to a dental phenomenon whereby a dog’s lower jaws (mandible) extend past the upper jaw (maxilla), consequently leading to a gap between the incisors of the upper teeth and those of the lower teeth. Because the teeth don’t fit as snugly as they naturally do, several problems often arise especially if the underbite is severe.

Other names for dog underbites include maxillary brachygnathism, undershot, prognathism, and reverse scissors bite. In veterinary medicine, underbites are classified as class 3 malocclusion.

A dog’s breed determines the typical bite or occlusion, that is, the bite considered as that breed’s standard. The scissor bite is considered the standard bite for dogs with more natural head shape (with long to medium-sized muzzle). Think of Labrador, Groodle, etc.

In the case of scissor bites, the dog’s incisor teeth touch each other with the lower jaw’s incisor teeth positioned slightly forward. When viewed from the sides, the teeth will seem to intersect snugly like a pair of scissors blades, hence the name scissor bite.

Any nonconformity to the scissor bite, in dog breeds with long to medium length muzzle, is referred to as malocclusion, a term that stands for teeth misalignment. A bite in which the lower jaw extends in front of the upper jaw is referred to as underbite whereas a bite in which the upper jaw extends in front of the lower jaw is referred to as an overbite.

Dog Breeds with Underbites  – What Dog Breeds Have Underbites?

Dog underbite is considered a normal occurrence for brachycephalic breeds such as English bulldog, French bulldog, Pug, Pekingese, Shih Tzu, Boxer, and Boston terrier. These breeds are characterized by short skulls and muzzles as opposed to the long muzzles observed in most dogs such as Labradors.

In fact, an underbite is considered a breed standard for certain breeds, including the bulldog and pug. If you have ever been to a dog show with one of these breeds and seen the judges checking dog’s teeth, then you now know what they were looking for. They wanted to ascertain that your dog’s bite or occlusion is in compliance with your dog breed standard.

The genetic propensity to dog underbite extends beyond pure breeds with short muzzles. Even designer breeds, or crossbreeds, with a pug, Maltese, or Cavalier King Charles Spaniel heritage have higher chances of developing an underbite. Puggle puppies, for example, tend to have an underbite since they have a pug heritage.

On a good note though, most cases of dog underbite will not have a serious complication or affect the dog’s life.

Note: Although dog underbite is common in the short-muzzled brachycephalic breeds, it can occur in any breed (including large and small breeds and even those with long muzzles), in which case it is considered a teeth misalignment.

What causes Underbites in Dogs?

Understanding the likely causes Dog underbite can help to reduce the risk as well as prevent the recurrence of the same in future generations. Dogs with underbites usually have one or more of the following as the underlying factors for the dentition:

  • Genetics: Genetics is the most obvious cause of dog underbite. The condition is hereditary which means that a dog with an underbite has high chances of passing the genes down to future generations. This is very true for brachycephalic breeds.
  • Dental abnormality: Puppies usually have 28 deciduous teeth or milk teeth. These are later replaced by permanent teeth and by the time they reach adulthood, dogs will have 42 permanent teeth. Sometimes, the milk teeth are not shed and instead continue growing alongside the adult teeth. This can be the underlying cause for a slight underbite.
  • Behavioral factors: It is also possible that the underbite has a behavioral factor behind it. This is, for example, the case when a teething puppy tugs at clothes, ropes etc. when playing a tug-of-war game, causing the growing adult teeth to shift from their usual alignment position.

Health Issues in Dogs with Underbites

Although most cases of underbites will not cause a problem and your companion dog will have just as high a quality of life, some problems often arise such as:

  1. Difficulty eating: The affected dog may find it difficult to grasp on and chew food. Such dogs tend to show a preference for large food particles.
  2. Periodontal disease: According to, dogs with underbite are at higher risk of periodontal disease than those with the standard bite. According to the PetMD, misaligned teeth also tend to accumulate tartar and plaque more easily.
  3. Teeth and soft tissues damage: Dog underbite often causes the upper teeth to rub against the inside of the lower teeth, consequently leading to traumatic wear of the affected teeth. The upper teeth can also cause traumatic damage to the soft tissues in the lower jaw.

Although they have serious complications, these health issues of dog underbite are very rare. Most dogs with underbite will have a normal life.

Dog Underbite Correction

The major concern for the owner of dogs with an underbite is the aesthetic aspect of it; some people find their dogs ugly. Despite their looks, these dogs will still lead a quality life. Treatment is usually not necessary.

Severe cases of dog underbite, especially those that cause serious traumatic injury to the tissues in the lower jaw – and thus pain – as to affect the dog’s quality of life may, however, benefit from corrective treatment. This is the only valid reason for treatment of dog underbites and often involves the following:

Corrective surgery typically involves tooth extraction to minimize traumatic injury and pain from abnormally positioned teeth. Any deciduous teeth in dogs aged over 10 months may also need to be removed. The procedure is usually carried out by a veterinarian specialized in dental procedures.

In some cases, the veterinarian will move the problematic teeth to minimize the traumatic injury of the soft tissues as well as damage to other teeth. Some teeth may also require shortening, in which case a procedure known as vital pulp therapy is performed. The ultimate goal of dog underbite correction surgery is to make the bite pain-free and as closely functional to typical dog bite as possible.

Surgical correction aside, it is also advisable to maintain optimum oral hygiene for your dog as having the underbite puts your pooch at an especially high risk of dental disease. Brush your dog’s teeth daily and give her some veterinary approved chews every now and then to minimize dental plaque and tartar buildup and the associated dental problems.

Dogs with underbites will still lead a normal life and make awesome companions.


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