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What is Overshot and Undershot Jaw?

Occlusion refers to the contact and alignment of the teeth in the upper and lower jaws. In normal occlusion, the lower incisors are overlapped by the upper incisors, called a scissor bite, the lower canines are equidistant between the upper canine teeth and the third lower incisor, and the premolars point to the spaces between the upper jaw teeth. Malocclusions occur when there are variations from the classic scissor bite, and can be caused by a misalignment of the jaws or teeth.

Overshot and undershot jaws are types of misalignments of the mandible, or lower jaw, and the maxilla, or upper jaw. Overshot refers to an upper jaw that is longer than the lower jaw, while undershot is when the lower jaw is longer. These misalignments, or malocclusions, can cause trauma, discomfort, and problems with eating in affected dogs.

Symptoms of Overshot and Undershot Jaw in Dogs

If your dog has an overshot or undershot jaw, he may have trouble closing his mouth. The slightly open mouth has sometimes been called salmon jaw, as it can resemble the open mouth of a fish. The longer upper jaw associated with overshot jaw can cause a parrot beak-like appearance. Besides looking unusual, a misaligned jaw can cause trauma and discomfort to various parts of the mouth as the misaligned teeth come into contact with tissues that would not be touched in normal occlusion. Signs your dog may have a misaligned upper or lower jaw include:

  • Overbite 
  • Protruding lower jaw
  • Abnormal jaw growth 
  • Incisors that meet edge to edge
  • Inability to close mouth
  • Slightly open mouth 
  • Difficulty chewing food
  • Preference for certain kinds of foods, such as bigger pieces
  • Inability to keep food in mouth while chewing
  • Salivation 
  • Rubbing at face
  • Oral pain
  • Hard palate trauma
  • Defects in the hard palate 
  • Lip or soft tissue trauma
  • Oral ulcers
  • Tooth wear
  • Exposure of tooth pulp
  • Tooth loss

Types

Overshot and undershot jaws are two types of malocclusions seen in dogs. Some defining features of each include:

Overshot

This is a Class II malocclusion that is also called mandibular brachygnathism, mandibular distoclusion, or an overbite. This type of misalignment is characterized by a shorter lower jaw and a longer upper jaw, which causes the lower canine teeth to strike the palate or upper canines. All dogs are born with an overshot jaw that allows them to nurse as new puppies. As the puppies grow, the lower jaw grows to catch up to the upper jaw. If the jaw does not have that growth spurt, it can cause displacement of the canines, which can then also inhibit the mandible growth.

Undershot

This is a Class III malocclusion that is also referred to as mandibular prognathism, maxillary brachygnathism, mandibular mesioclusion, or an underbite. This malocclusion is characterized by a shorter upper jaw and a longer lower jaw, resulting in lower teeth that are in front of the upper teeth. While this condition is normal for some breeds, such as Bulldogs, in many breeds it is unusual. An undershot jaw occurs when the lower jaw grows faster than normal and becomes longer than the upper jaw, and is usually evident around 8 weeks of age in puppies. This misalignment can cause soft tissue trauma, such as to the lips. When the incisors meet instead of fitting next to each other, it is called a level bite. When the malocclusion causes the lower incisors to be placed in front of the upper incisors, it is called a reverse scissors bite.

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Causes of Overshot and Undershot Jaw in Dogs

The cause of overshot and undershot jaws in dogs relate to the increased or decreased rate of growth of the upper and lower jaws in relation to one another. This can occur due to a:

  • Genetic disorder
  • Trauma
  • Systemic infection
  • Nutritional disorder
  • Endocrine disorder
  • Abnormal setting of puppy teeth
  • Early or late loss of puppy teeth
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Diagnosis of Overshot and Undershot Jaw in Dogs

If you have noticed that your dog’s jaw seems abnormally shaped, or that he is having a hard time chewing or keeping food in his mouth, you may need to take your dog in to your veterinarian. After a quick physical exam, your vet may have to sedate your dog in order to perform a thorough oral exam. This will assess your dog’s skull type and teeth location in relation to the teeth on the opposite jaw.

Often, the placement of the upper and lower incisors in relation to one another can determine what type of malocclusion your dog has. Your vet will note any areas of trauma due to teeth striking those areas, and any cysts, tumors, abscesses, or remaining puppy teeth that may be present. A dental X-ray can also help to assess the health of the jaws and teeth. These diagnostic methods will lead to a diagnosis of an overshot or undershot jaw in your dog.

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Treatment of Overshot and Undershot Jaw in Dogs

Treatment of a jaw misalignment will depend on the severity of the condition. If your dog has a misalignment, but can still bite and chew food without problems, no treatment may be needed. If the misalignment is caught early in a puppy’s life, it may only be temporary and may correct itself over time.

However, there are times when intervention may be needed. If your puppy’s teeth are stopping the normal growth of his jaws, then surgery to remove those puppy teeth may be performed. This may allow the jaws to continue to grow, but will not make them grow. 

For older dogs who are experiencing pain and trauma due to misaligned jaws and teeth, oral surgery is generally performed to extract teeth that are causing trauma, to move teeth so that they fit, or to create space for a misaligned tooth to occupy. Other therapies include crown reductions or braces.

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Recovery of Overshot and Undershot Jaw in Dogs

Overshot and undershot jaws in dogs are often genetic defects that cannot be controlled. As such, the earlier the intervention, the better the outcome for your dog. While the condition can be severe if the misalignment causes your dog to be unable to eat, in many cases, orthodontic intervention can lessen the pain and trauma associated with malocclusion and help your dog to comfortably live with the condition. Recovery will depend on how early the condition was treated and how mild or severe it is, but is generally fair.

If your dog is genetically programmed to have an overshot or undershot jaw, intervention can help, but will not slow or stop the abnormal growth of either jaw. Prevent jaw misalignments in puppies by not breeding dogs who have overshot or undershot jaws.

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Overshot and Undershot Jaw Questions and Advice from Veterinary Professionals

Need pet health advice? Ask a vet

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Ask a Vet

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Jenny

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Shetland Sheepdog

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5 Weeks

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Fair severity

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1 found helpful

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Fair severity

Has Symptoms

Undershot Jaw Allignment.

I have a 5 week old Sheltie puppy with an undershot jaw. Her sibling have their deciduous teeth in already but her baby teeth are not all in yet (incisors are not all in). Malocclusion does not seem to be in either of the champion breeding lines. Is it too soon to be worried?

Sept. 11, 2018

Jenny's Owner

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heidi

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Russian Toy Terrier

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12 Weeks

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Fair severity

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Fair severity

Has Symptoms

Undershot Bite

I have 12 week old russian toy terrier with an undershot bite. The gap between her top and bottom canine is about 0.2 cm or the size of a matchstick head. They dont stick out to the side and dont seem to be causing any problems right now. Would you recommend having her top baby incisors removed to allow proper growth? Her top incisors fit directly behind the lower and are not visible from the front when her jaw is closed.

Aug. 21, 2018

heidi's Owner

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3320 Recommendations

If the upper incisors are sitting behind the lower ones it may be an idea to think about extractions, however this is something to speak with your Veterinarian about since I cannot say for certain without examining Heidi first and each case is different. The level of malalignment is small and may resolve with growth. Regards Dr Callum Turner DVM

Aug. 22, 2018

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Elsa

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Siberian Husky

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7 Weeks

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Mild severity

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Mild severity

Has Symptoms

Undershot Bite

We are getting a Siberian Husky and have visited the litter a couple of times, we never noticed something odd with our first choice except that she was relatively "shy" and had slightly droopy eyes. The owner took them to the vet for their first vaccine and turns out she has an undershot jaw. I keep reading that the lower part of a dog's jaw continues to grow and I am worried if it will get worse with time. Also, we didn't find anything on Huskies with undershot bites. Does anyone have experience with this? Should we consider another pup in the litter? Will it get worse?

June 28, 2018

Elsa's Owner

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Dr. Michele K. DVM

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1611 Recommendations

Elsa's bite will probably not get worse over time, as their skulls grow at the same rate. Whether you decide to keep her probably depends on the degree of malocclusion, and without seeing her, I can't comment on that. If it is severe, it may need some corrective work, but if it is mild, it will probably not affect her life at all.

June 29, 2018

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Apollo

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Vizsla

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5 Months

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Fair severity

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Undershot Jaw

I have a 5 month old Vizsla pup who seemingly had a normal bite before he started losing teeth. Now that he’s lost all his front teeth besides canines, his middle bottom four teeth are overlapping the upper middle two teeth. The other smaller teeth around them till the canines are fine. Will this correct itself over time, or will he continue to develop a reverse scissor bite?

May 17, 2018

Apollo's Owner

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Dr. Michele K. DVM

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1611 Recommendations

Without actually seeing Apollo's teeth, I can't comment on whether they are coming in normally or not, unfortunately. It would be best to have him seen by a veterinarian who can assess his dentition, and refer you to a veterinary dentist if needed. It is good that you are paying attention to this now, while it can be fixed if needed.

May 17, 2018

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Qarezze

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Staffordshire Bull Terrier

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6 Months

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Moderate severity

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Moderate severity

Has Symptoms

Undershot, Difficulties Eating

I have a puppy now 6 months old and when he still had his puppy teeth all was normal. Perfect bite everything. But now he had started changing his teeth and he become undershot. It has gotten to the point I can almost put my finger between the lower and upper teeth. He starts to have difficulties chewing he food and is becoming a very slow eater, so I think he might be experiencing some pain aswel. Not all teeth have changed yet so I wanted to know what your suggestion would be in this case.

May 16, 2018

Qarezze's Owner

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Dr. Michele K. DVM

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1611 Recommendations

Most dogs actually do quite will with imperfect bites, and they are quite common. It would be best to have Qarezze seen by a veterinarian for his mouth, though, as sometimes the teeth can cause problems, and there may be something that they can do by taking certain teeth out while they are still developing. Since I cannot see him, it would be a good idea to have him examined. I hope that all goes well for him!

May 16, 2018

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Huckle

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Labrador Retriever

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5 Months

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Serious severity

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0 found helpful

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Serious severity

Has Symptoms

Difficulty Eating
Messy Drinking
Difficulty Picking Up

I have a 5 month old Labrador with a severe overshot. His bottom jaw has not had the growth spurt so it hasn't grown as it should have done when he was a younger puppy. My vet has referred him to a specialist dental vet and we are waiting for an appointment. What is the dental vet likely to do? can it be corrected somehow so his bottom jaw will grow ?

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Kingston

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English Springer Spaniel

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6 Months

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Fair severity

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Fair severity

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Overbite

I have a 6 month old wpringer spaniel whos lower bottom 2 canines are making holes in the roof of his mouth, the vet says either removal of the teeth or cutting and tipping them. My breeder says that the jaw is still growing until 10 months of age and we should wait some months as it may right itself? What should we do?

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Bolt

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Rottweiler

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6 Months

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Fair severity

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Fair severity

Has Symptoms

Underbite

I have a 6 months old Rottweiler with underbite but not externally visible.Will it correct?get bad over time?or remain the same?As he can grow for at least a year I am worried weather it will get worse and become cosmetically visible.

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