Occasionally, we refer to a young puppy as a “shark mouth,” not necessarily because of her penchant for nipping at exposed flesh, but because she has double rows of teeth. Like people, cats and dogs should have one row of teeth, with adult teeth replacing their baby teeth. However, a pet’s baby teeth may hold on tightly, despite her adult teeth having erupted, creating that double row of teeth, and earning the pet the “shark mouth” nickname.

To clear up any confusion, let’s discuss the correct terminology for teeth. Baby teeth that are still in place after the adult teeth have come in are often mistakenly referred to as “retained,” which is incorrect. The following definitions will help you understand appropriate dental terms:

  • Primary — A pet’s first teeth, often referred to as “baby teeth”
  • Deciduous — Another term for primary teeth—the term “deciduous” refers to trees that shed leaves as they mature
  • Secondary — Adult teeth
  • Retained — Primary teeth that persist, where secondary teeth are not present
  • Persistent — Primary teeth that are still present, despite the eruption of secondary teeth

Many people confuse “retained” and “persistent,” calling those extra baby teeth retained teeth, when they are actually persistent teeth. A primary tooth rarely exists without an accompanying secondary tooth, which can be seen visually, or on dental X-rays, but in these cases, “retained” teeth is appropriate.

What are persistent baby teeth in pets and how do they occur?

In cats and dogs, primary tooth roots are normally resorbed from the pressure of the permanent teeth erupting, and pushing them out of the tooth socket. Similar to cats suffering from resorptive disease, neither the process that causes primary root resorption, nor the reason resorption fails, are fully understood. However, the secondary tooth is thought to be positioned incorrectly, and not enough pressure for primary tooth root resorption is produced. Since the body fails to resorb the primary tooth roots, and they are still intact, the secondary tooth tries to develop from the same tooth socket, leading to the condition known as persistent primary teeth. 

How many teeth should my pet have?

Some pets’ dentition can be a little wonky, and out of line. Brachycephalic breeds— particularly pugs, bulldogs, and Persian cats—are the most prone to tooth-position irregularities, so determining if they have the correct number of secondary teeth can be challenging. In pets who follow typical dentition rules, the number of primary and secondary teeth should be:

  • Kittens — 26 primary teeth
  • Cats — 30 secondary teeth
  • Puppies — 28 primary teeth
  • Dogs — 42 secondary teeth

In cats, the primary incisors begin to appear at 2 to 4 weeks of age, and the primary premolars at 5 to 6 weeks. Secondary teeth usually begin to erupt at around 4 to 7 months of age.

Dogs develop teeth more slowly, with primary teeth beginning to erupt at 3 to 5 weeks of age, and secondary teeth usually appearing around 4 to 5 months. All secondary teeth are present by the time the dog reaches 7 months of age.

What pets are most commonly affected by persistent baby teeth?

Dogs—particularly toy and small breeds—are much more likely to have persistent primary teeth than cats. The breeds known to most commonly hold on to their baby teeth after their adult teeth have grown in include:

  • Maltese
  • Yorkshire terriers
  • Pomeranians
  • Miniature schnauzers
  • Chihuahuas

Because most persistent primary teeth are genetic, breeding pets with this dental issue is not recommended.

What periodontal issues can persistent baby teeth cause in my pet?

Persistent primary teeth can create many uncomfortable dental issues. When these teeth overcrowd the mouth, the secondary teeth are moved to abnormal locations, leading to oral discomfort. The hard palate can suffer trauma, if the primary mandibular canine teeth displace the secondary canine teeth. Double sets of roots may also prevent the periodontal support from developing normally around each permanent tooth, resulting in early tooth loss. If your pet’s mouth is overcrowded with additional teeth, more food, fur, and other debris will likely be trapped, creating an increased bacterial load, which results in faster periodontal disease development. 

How are persistent baby teeth managed in pets?

A persistent primary tooth should be extracted as soon as the permanent tooth erupts in the same tooth socket. If we extract the persistent primary tooth early enough, the secondary tooth will often move into the correct position, avoiding future bite issues. To ensure the persistent primary tooth does not have roots that are slow to resorb, and it truly requires extraction, we will take dental X-rays before oral surgery. The X-rays will also allow us to check for embedded or impacted secondary teeth, or other issues that may be causing an abnormal dentition of permanent teeth. 

Is your puppy a prime candidate for the “shark mouth” nickname? If your pet has persistent primary teeth, call the Animal Dental Clinic to schedule an oral evaluation, to see if extraction is necessary.