Malocclusion in Dogs and Cats: Symptoms, Causes, and Veterinary Care

TL;DR. Malocclusion is an abnormal alignment of the teeth or jaws, common in dogs and cats, which can cause painful crowding and dental disease but carries an excellent prognosis with proper lifelong care.

Malocclusion often results in crowded, rotated teeth that are difficult to keep clean.

What is it?

In a healthy dog or cat, the teeth and jaws align in a precise, functional arrangement known as normal occlusion. In dogs, this is typically a "scissor bite," where the upper incisors overlap the lower incisors, and the lower canine teeth fit cleanly into the space between the upper outer incisor and the upper canine tooth. This alignment allows for efficient chewing, grasping of food, and self-cleaning of the teeth during mastication. When this alignment is disrupted, the condition is known as malocclusion.

Malocclusion can be broadly categorized into two types: skeletal and dental. Skeletal malocclusion occurs when there is an inherited discrepancy in the growth patterns of the upper jaw (maxilla) and the lower jaw (mandible). When one jaw grows faster or longer than the other, the teeth cannot meet normally. Dental malocclusion occurs when the jaw lengths are normal, but individual teeth are rotated, crowded, or erupt in abnormal directions due to space constraints or retained baby teeth.

Understanding how teeth fit into the jaw is essential for recognizing the impact of this condition. In small and toy breeds, the jawbones have been significantly reduced in size through selective breeding, but their teeth have not shrunk at the same rate. A leading veterinary anatomy textbook describes this structural challenge:

"The size of the teeth does not decrease proportionately with a reduction in the length or width of the bones containing them (Stockard, 1941). The result is crowded large teeth in small mouths predisposing toy breeds and breeds smaller than 20 pounds to a higher incidence of periodontal disease."

Because of this disproportion, even a mild misalignment can lead to severe dental crowding, trapping food and bacteria, and accelerating oral disease.

Causes & risk factors

Malocclusion is primarily a hereditary condition. The genes that control jaw length and width are inherited independently from the genes that control tooth size. When these genetic instructions do not align, the pet develops a mismatched bite.

In brachycephalic (flat-faced) breeds, human selection for short muzzles has compressed the upper jaw while the lower jaw remains relatively normal. This leads to a condition called mandibular prognathism, or an "undershot" jaw. Conversely, in dolichocephalic (long-nosed) breeds, the lower jaw may be abnormally short, a condition known as mandibular brachygnathism, or an "overshot" jaw.

While genetics is the primary driver, developmental factors can also cause or worsen malocclusion. If deciduous (baby) teeth do not fall out when they should, they can push the emerging permanent teeth out of their proper alignment. Trauma to the face or jaw during growth can also damage the growth plates of the jawbones, leading to asymmetrical jaw development and secondary malocclusion.

Signs to watch for

Many pets with mild malocclusion show no outward signs of discomfort and can eat normally. However, as the misalignment becomes more severe, physical and behavioral signs will emerge. Owners should watch for the following symptoms:

• Rotated teeth (Common): Teeth that are turned sideways or at odd angles to fit into a crowded jaw.
• Crowded teeth (Common): Teeth packed tightly together, leaving no space between them, which easily traps food and debris.
• Temporomandibular joint (TMJ) abnormalities (Occasional): Misaligned jaws can place uneven strain on the jaw joints, leading to clicking, discomfort, or difficulty opening and closing the mouth.
• Pain (Occasional): Pain can occur if misaligned teeth strike the sensitive soft tissues of the mouth (such as the palate or gums) or if advanced periodontal disease develops due to crowding.
• Abnormal mastication (Occasional): Chewing on only one side of the mouth, dropping food, or chewing with an unusual head tilt.
• Prehension difficulty (Occasional): Difficulty picking up food or toys from the ground.
• Tooth loss (Occasional): Chronic periodontal disease in crowded areas can destroy the supporting bone, leading to loose teeth that eventually fall out.

Mandibular prognathism, or an undershot jaw, is a common form of skeletal malocclusion in brachycephalic breeds.

How vets diagnose it

Your vet will diagnose malocclusion primarily through a thorough visual examination of your pet's mouth. This is the gold standard for identifying bite abnormalities. During a routine wellness exam, the vet will evaluate how the upper and lower teeth meet, checking the alignment of the incisors, the positioning of the canine teeth, and the interlocking of the premolars and molars.

To document their findings precisely, veterinarians use a standardized dental numbering system. As described in a prominent veterinary anatomy reference, the mouth is divided into quadrants:

"Numbers 1 to 4 indicate permanent teeth, with 1 referring to the superior right quadrant, 2 for the superior left quadrant, 3 for the inferior left quadrant, and 4 for the inferior right quadrant. In a similar fashion 5 to 8 are used for the deciduous teeth. The second and third digits identify the specific tooth. Numbering is consecutive and starts with the most mesial tooth (incisor 1)..."

Using this system, your vet can record exactly which teeth are rotated, crowded, or causing painful contact with soft tissues.

Because much of the tooth structure and supporting bone lies beneath the gumline, skull radiography (dental X-rays) is essential. Radiographs allow your vet to evaluate the health of the tooth roots, check for hidden pockets of infection, and identify teeth that may be impacted or failing to erupt. This imaging is typically performed under general anesthesia to ensure clear, high-quality images and to protect your pet from discomfort.

Dental radiographs allow veterinarians to evaluate the health of crowded tooth roots beneath the gumline.

Treatment options

Treatment for malocclusion is focused on ensuring your pet has a functional, pain-free bite, rather than achieving cosmetic perfection. If the malocclusion is not causing pain, tissue damage, or severe dental disease, no active treatment may be required beyond diligent home care.

Dental Hygiene and Prophylaxis

Because crowded and rotated teeth are highly prone to periodontal disease, professional dental cleanings under anesthesia are critical. Your vet will scale away plaque and tartar from above and below the gumline and polish the teeth to smooth the enamel. Regular professional cleanings, combined with daily at-home tooth brushing, are the cornerstone of managing malocclusion.

Surgical Extractions

If a misaligned tooth is striking the soft tissues of the mouth (such as the roof of the mouth) and causing painful ulcers, or if dental crowding has led to advanced periodontal disease, extraction is often the most effective treatment. Removing the offending or severely diseased teeth immediately eliminates pain and prevents infection from spreading to neighboring teeth.

Orthodontic and Restorative Therapies

In select cases, particularly in younger animals where teeth can still be guided into place, orthodontic appliances may be used. These can include custom-made acrylic splints or inclined planes that gently guide erupting teeth into a functional position. A leading veterinary surgery textbook describes the materials used for these custom appliances:

"The homemade splint consists of methylmethacry-late, which can be obtained as either hoof repair... or dental molding acrylic... The acrylic column can be free-formed or injected into a tube to serve as a mold. When free-formed, the acrylic is molded by hand to the required shape."

These specialized procedures are typically performed by a board-certified veterinary dentist to ensure the appliance does not cause discomfort or damage the developing teeth.

Prognosis

The long-term prognosis for pets with malocclusion is excellent for life. The condition itself is not life-threatening, and most pets adapt remarkably well to their unique jaw structures. However, because chronic dental crowding predisposes these pets to periodontal disease, they will require ongoing, lifelong dental care. Without regular intervention, plaque buildup can lead to painful oral infections, bone loss, and systemic health issues. With proactive veterinary care and consistent home hygiene, pets with malocclusion can live long, comfortable, and happy lives.

Prevention

Because malocclusion is primarily an inherited genetic condition, it cannot be prevented through lifestyle modifications or diet. The most effective prevention is selective breeding. Dogs and cats with significant skeletal malocclusions should not be bred, as they are highly likely to pass these genetic traits on to their offspring.

For pet owners, early detection is key. Having your puppy or kitten's mouth evaluated by a veterinarian during their initial vaccine visits allows for early identification of retained baby teeth or developing jaw discrepancies. Intervening early—such as extracting retained baby teeth before they can redirect permanent teeth—can significantly reduce the severity of adult malocclusion.

When to call your vet

While mild malocclusion is not an emergency, you should schedule an appointment with your veterinarian if you notice any signs of oral discomfort or dental disease.

Contact your veterinarian immediately if your pet exhibits any of the following red flags, which indicate severe pain or infection:

• Inability to eat or complete reluctance to chew food
• Pawing at the mouth or rubbing the face against furniture
• Bleeding from the mouth or blood on chew toys
• Swelling of the face, particularly under the eyes or along the jawline
• A foul, putrid odor coming from the mouth
• Dropping food repeatedly or crying out while attempting to eat

For specific breeds

Certain breeds are highly predisposed to specific types of malocclusion due to their inherited skeletal structures.

Brachycephalic Breeds

Breeds with shortened muzzles are highly prone to mandibular prognathism (undershot jaw) and severe dental crowding. A prominent veterinary anatomy reference notes:

"In some brachycephalic breeds, the English Bulldog, for example, the ventral jaw protrudes rostral to the dorsal jaw, producing the undershot condition known as prognathism of the mandible."

This presentation is also commonly suspected or observed in other flat-faced breeds, including the French Bulldog, Boston Terrier, Brussels Griffon, and Pekingese. In these breeds, the teeth are often rotated almost 90 degrees to fit within the shortened jawbone.

Dolichocephalic and Narrow-Muzzled Breeds

Conversely, breeds with long, narrow muzzles are predisposed to mandibular brachygnathism, where the lower jaw is abnormally short. According to veterinary anatomy texts, "both the Collie and the Dachshund frequently exemplify this condition." Other breeds with suspected or observed predispositions to jaw length discrepancies include the Basset Hound, Saluki, and Greyhound.

Note on Feline Extrapolation: While malocclusion is well-documented in cats—particularly in brachycephalic breeds like Persians—much of the detailed anatomical classification and structural research in veterinary literature is extrapolated from canine models.

Sources

• Miller and Evans Anatomy of the Dog, 5th Edition, page 198, 676.
• Current Techniques in Small Animal Surgery, 5th Edition, page 746.