Equine Dentistry
2002 SAVMA Symposium
Joe B. Stricklin, DVM
Equine Field Services, Equine Sports Medicine Unit
Veterinary Teaching Hospital
Colorado State University

A. Anatomy

1.  Deciduous (Baby or Milk) Teeth
A total of 24 deciduous or milk teeth develop in the young horse. Twelve incisors or cutting teeth and 12 premolars or grinding teeth develop. The deciduous canine teeth are vestigial and do not erupt. There are no deciduous molars. Table 1 describes the dates of eruption of deciduous and permanent teeth.

2.  Permanent Teeth
Permanent incisors replace the deciduous incisors at 2.5 years (inside pair), 3.5 years (middle pair) and 4.5 years (outer pair), respectively. Canines are almost always present in the stallion and are only occasionally present in the mare. The first premolar, often referred to as the wolf tooth, may be absent or rudimentary and is usually found only on the upper arcade. Adults possess three premolars and three molars on each side on both the upper (maxillary) and lower (mandibular) dental arcades. In the horse, the term ‘cheek teeth’ is often used to describe the permanent premolars and molars combined (i.e., the fourth lower cheek tooth is the first molar). The total number of teeth in the adult stallion is 42, if upper wolf teeth are present.

 

Eruption Dates

Tooth

Deciduous

Permanent

First incisor

Birth to 1 week

2.5 years

Second incisor

4 to 6 weeks

3.5 years

Third incisor

6 to 9 months

4.5 years

Canine

 

4 to 5 years

First premolar (Wolf tooth)

 

5 to 6 months

Second premolar

Birth to 2 weeks

2.5 years

Third premolar

Birth to 2 weeks

3 years

Forth premolar

Birth to 2 weeks

4 years

First molar

 

9 to 12 months

Second molar

 

2 years

Third molar

 

3.5 to 4 years

B. Signs of a Dental Problem:

1.  Quidding – dropping semi-chewed food from the mouth

2.  Spilling/Spitting grain

3.  Inefficient mastication

4.  Cheek sensitivity

5.  Abnormal cheek swelling

6.  Sensitivity to bit

7.  Head shaking or tilting

8.  Foul odor from mouth or nose

9.  Excessive salivation

10. Exaggerated tongue movements

11. Pain when drinking cold water

12. Bleeding from mouth

13. Rough hair coat

14. Weight loss

C. Dental Examinations

These should be performed on a routine basis so as to prevent severe problems from developing. These may be scheduled during visits for annual vaccinations. Young horses (2 year olds) should be checked just as much as older horses should. Young horses have soft teeth which allow points to occur quickly leading to the need to float more often. Lack of care could lead to poor training as these young animals begin to go into bits.

D.Oral or Dental Problems

1.  Dental Caps – deciduous teeth (usually cheek teeth) retained even after the permanent tooth has erupted fully above the gum line. A distinct demarcation between the cap and permanent tooth is evident after full eruption. Retained deciduous teeth may result in impaction or prevention of normal eruption of the permanent teeth. Caps may fragment and result in laceration, infection and swelling of the gums, tongue or cheeks. Retained deciduous incisors may cause displacement of the permanent incisors to the inside.

2.  Lampas – swelling of the mucous membrane of the hard palate that occasionally occurs during the eruption of incisor teeth.
Treatment – Swelling will subside without treatment. Historically, many techniques (often cruel) were used in an attempt to treat this condition, such as burning with a hot iron bar.

3.  Two-year-old bumps – swellings along the mandible due to the presence of tooth roots of the permanent premolars. Swellings are more pronounced when dental caps are retained and premolars are impacted.
Treatment – None necessary for normal horse; remove dental caps if present.

4.  Wolf Teeth – refers to the first permanent premolar (PM-1) which, if present at all, is usually a vestigial or rudimentary structure in the upper arcade. Usually located immediately adjacent to or touching the second premolar (the initial large, permanent cheek tooth). Often blamed for causing difficulty with the bit.

5.  Canine Teeth – the 4 teeth (one on each upper and lower arcade) located behind the incisors and in front of the cheek teeth in the interdental space. The lower canines are located more forward than the upper canines, when present. Canines are almost always present in the male, while those in the mare are very small and may not erupt. Nonerupted canines in the mare may cause gum irritation; erupted canines may develop very sharp tips.

6.  Enamel Points – sharp outer edges of the upper cheek teeth and inner edges of the lower cheek teeth which form due to the incomplete overlap of the upper and lower arcades of cheek teeth in the horse and uneven wear on the occlusal surfaces during side-to-side chewing.
Treatment – Rasping or 'floating' down the points by use of specialized equine dental tools called 'floats'.

7.  Molar Hooks – due to misalignment of the upper and lower jaw (see Parrot mouth description), where the upper jaw lies forward relative to the lower jaw. The front portion of the first upper cheek tooth (premolar-2) does not wear against a lower tooth and continues to grow, developing the 'hook'. Similarly, the back portion of the last lower cheek tooth (molar-3) does not have an upper molar to wear against and also continues to grow into a 'hook'.
Treatment – Rasp or 'float' down the hooks or cut off with molar cutters.

8.  Woodchewing – a common destructive behavior (vice) when horses repeatedly bite or chew on objects such as stall doors, feed racks or fence rails; often seen in horses fed low fiber or low protein diets or complete pelleted diets; may begin due to inactivity or boredom; results in abnormal wear pattern on incisors.
Prevention – Dietary changes (provision of roughage), toys, companions, exercise programs and treatment of wooden surfaces with noxious substances or electric wiring.

9.  Cribbing (Windsucking, Stumpsucking) – Another addictive vice in which horses grasp a fixed surface with their upper incisors, arch their necks and suck in air. Usually due to inactivity or boredom, but may be learned from observing other horses windsucking. Problems associated with windsucking include excessive incisor wear, hypertrophy of neck muscles, weight loss and owner frustration; may be associated with an increased risk of abdominal discomfort (colic).
Prevention – Cribbing strap placed around the neck behind the jaw, coating fixed surfaces with noxious substances and surgery.

10. Sheer Mouth – malocclusion of the cheek teeth resulting in severe point formation due to the presence of an upper jaw that is significantly wider than the lower jaw. May result in a malocclusion of cheek on one side or both sides of the mouth.
Treatment – Float.

11. Wave Mouth – Uneven wear pattern (undulating or wave-like) of upper and lower cheek teeth where some teeth are abnormally long and the opposite teeth are worn excessively. More common in older horses and ponies. Often occurs in conjunction with parrot mouth and retained dental caps.
Treatment – Float; remove dental caps if present.

12. Step Mouth – Presence of abnormally long teeth; usually caused by the loss of the corresponding tooth in the opposite arcade as there is no longer a tooth to wear on during chewing.
Treatment – Rasp (float) down the long tooth or cut with molar cutters.

13. Cracked or Fractured Teeth – equine teeth are occasionally broken either horizontally or vertically, usually by blunt trauma. Broken teeth are usually not a problem unless the tooth subsequently becomes infected.
Treatment – removal if tooth infected or painful

14. Periodontal Disease – inflammation of the oral mucous membrane that is attached to the teeth and surrounding bone. May be due to eruption of permanent teeth, gingival erosion, infection, presence of a foreign body (i.e., plant awn embedded in gums), irritation from a bit, trauma and un-erupted teeth (i.e., rudimentary lower canine teeth in the mare).
Treatment – specific treatment varies with source of inflammation.

15. Tooth Root Abscesses – collection of pus around the root of a tooth as a result of an infection. The roots of the third and fourth upper cheek teeth are usually located in the anterior maxillary sinus and the roots of the fifth and sixth upper cheek teeth are usually located in the posterior maxillary sinus.
Treatment – Remove affected tooth.

16. Extra (Supernumerary) Teeth – teeth present in addition to the normal number found in the mouth of a given species. With age, the additional tooth, which does not have occlusal contact with another tooth, will elongate and need attention. The normal number of permanent teeth in the adult male horse is 42 or 40, depending on the presence or absence of wolf teeth. Females often lack upper and lower canines as well. The normal number of deciduous (milk) teeth is 24.
Treatment – Remove extra teeth if affecting the eruption of normal permanent teeth. Float or rasp if excessively long.

17. Tongue lacerations – may be due to a sharp bit, chewing on wire or sheet metal, retained fractured caps, sharp enamel points or other traumatic injuries.
Treatment – small tongue lacerations generally heal well without treatment. Large lacerations may need medical attention.

E. Preventive Dental Care

Floating–This is the act of filing or rasping the sharp edges from the outer (buchal) surfaces of the upper teeth and the inner (lingual) surfaces of the lower cheek teeth. This may be done with manual tools or different types of power tools or a combination of both depending on the severity of the problem.

Routine oral examinations of the horse start shortly after birth. One should look for the presence of congenital problems such as cleft palate and malocclusion (i.e., parrot mouth). Specific age-related dental care in young horses includes:

 2–3 yr. olds – wolf teeth may be pulled if present; first permanent cheek teeth (PM-2) examined for caps; points floated

 3–4 yr. olds – second permanent cheek teeth (PM-3) examined for caps; points floated

 4–5 yr. olds – third permanent cheek teeth (PM-4) examined for caps; points floated

 Adult horses should be examined at 6–12 month intervals throughout life. Dental treatments may not be needed at each examination. However, when problems are detected, early treatment is generally easier (and cheaper) than dealing with a much more severe problem which has gone undiagnosed for a long time.

Preventive dental maintenance results in improved feed utilization as horses chew roughage and grain more thoroughly and consequently digest them more completely. Horses with good dental care are therefore generally in a better body condition than horses whose teeth are ignored.

Finally, maintenance of good teeth through proper dental care reduces the incidence of gastrointestinal disorders, such as choke and colic.

Speaker Information
(click the speaker's name to view other papers and abstracts submitted by this speaker)

Joe B. Stricklin, DVM
Equine Field Services, Equine Sports Medicine Unit
Veterinary Teaching Hospital
Colorado State University


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