NVAP Reference Guide: Appendix G: Equine Teeth and Aging

Last Modified: March 20, 2024



Control and Eradication


Aquatic Animal

Animal Health Emergency Management

Animal Movement

Animal Identification 


The age of horses, donkeys, and mules can be estimated by examining the eruption and wear patterns of the teeth. Figures 7 through 9 provide a usable reference to help the accredited veterinarian approximate a given horse’s age. These figures are reprinted with the permission of the American Association of Equine Practitioners from the “Official Guide for Determining the Age of the Horse.” 

Skull of a colt

In determining the age of a horse by its teeth, the examination is usually limited to the incisors. Eruption of the premolars and molars (cheek teeth) is a fairly accurate indication of age but is used infrequently. After the permanent teeth are in wear, determination of age becomes more difficult and quite speculative. No single feature or sign along should be considered as reliable; all signs must be evaluated carefully. The eruption table given here is from Sisson and Grossman (19xx).

Eruption of the Teeth

The subjoined table indicates the average period of the eruption of the teeth.

A. Deciduous: 
First incisor (Di 1)Birth or first week
Second incisor (Di 2)4-6 weeks
Third incisor (Di 3)6-9 months
Canine (Dc) 
First Premolar (Dp 2)Birth or first 2 weeks
Second premolar (Dp 3)Birth or first 2 weeks
Third premolar (Dp 4)Birth or first 2 weeks
B. Permanent: 
First Incisor (I 1)2 1/2 years
Second incisor (I 2)3 1/2 years
Third incisor (I 3)4 1/2 years
Canine (C)4-5 years
First premolar or wolf-tooth (P 1)5-6 months
Second premolar (P 2)2 1/2 years
Third premolar (P 3) 3 years
Fourth premolar (P 4)4 years
First molar (M 1)9-12 months
Second molar (M 2)2 years
Third molar (M 3)3 1/2 -4 years
(The period given for P 3 and 4 refer to the upper teeth; the lower ones may erupt about 6 months earlier.)
Black and white image of horse teeth

The Incisive Arcades 

When the incisors are viewed in profile, the angle between the upper and lower i11cisors becomes more acute with age.

Black and white photo of Horse incisor teeth

Schematic Drawing of Incisors, Irregular Wear 

Illustration depicts teeth of excessive length, whjch may have resulted from too-acute angulation at a n early age, improper wear, or maintenance of the horse of a soft diet. Each line on the corner tooth represents approximately 1year's growth. If table (occlusal) surfaces of incisors indicate age of 10 years and teeth were as illustrated, showing 10 lines, the age of the horse may be estimated as 20. (Number of lines added to indicated age of table surfaces equals estimated age.) 

Schematic Drawing of Central Incisor - Horse

Figure 9 - Equine incisors at various ages on the following pages (2.11 MB). (Scanned from the Official Guide for Determining the Age of the Horse, Published by the American Association of Equine Practitioners.)