Teeth & Age Determination by Dentition Veterinary Anatomy

High-Yield Points:
• Heterodont (different shaped teeth) and diphyodont (deciduous + permanent).
• Dental formula (Permanent Ox): I 0/3, C 0/1, P 3/3, M 3/3 = 32 teeth.
• Ox has NO upper incisors or canines — replaced by dental pad. The lower 'canine' is incisiform, so 4 lower 'incisors' = I1, I2, I3, C.
• Horse: I 3/3, C 1/1 (rudimentary in mare), P 3-4/3, M 3/3 = 36-44.
• Dog: I 3/3, C 1/1, P 4/4, M 2/3 = 42.
• Age determination by dentition: based on eruption + wear of incisors.

TEETH OF DOMESTIC ANIMALS

Tooth Structure: Crown (above gum) + Root (in alveolus). Tissues: enamel (hardest), dentine, cementum, pulp (with vessels & nerves).

Types of Teeth: Incisors (I) for cutting; Canines (C) for tearing; Premolars (P) + Molars (M) for grinding (cheek teeth).

Hypsodont vs Brachydont:
• Hypsodont (high-crowned) — horse and ruminants; equine cheek teeth undergo prolonged eruption from a finite reserve crown. Rabbits have aradicular, continuously growing teeth.
• Brachydont (low-crowned) — dog, cat, pig and human.

OX DENTAL FORMULA:
Deciduous: 2(Di 0/4, Dc 0/0, Dp 3/3) = 20 teeth.
Permanent: 2(I 0/3, C 0/1, P 3/3, M 3/3) = 32 teeth.
Note: lower canine in ox is INCISIFORM (looks like an incisor) → so 4 lower 'incisor-like teeth' on each side.

HORSE DENTAL FORMULA:
Permanent: 2(I 3/3, C 1/1, P 3-4/3, M 3/3) = 36-44 teeth.
Mare often lacks canines; may have 'wolf tooth' (vestigial P1).

DOG DENTAL FORMULA: 2(I 3/3, C 1/1, P 4/4, M 2/3) = 42.

AGE DETERMINATION BY DENTITION (Cattle):
Examines eruption and wear of permanent lower incisors:
• Birth — incisors not erupted (deciduous appear in days).
• 1.5-2 years — central permanent I1 erupt.
• 2.5-3 years — I2 erupt.
• 3-3.5 years — I3 erupt.
• 3.5-4 years — corner 'canine' erupts ('full mouth').
• Beyond 5 years — wear pattern of incisors used; 'leveling' progresses from medial to lateral with age.

AGE DETERMINATION BY DENTITION (Horse) — 'Galvayne's groove' on the upper corner incisor + cup wear pattern:
• Cups disappear from lower I1 at ~6 yrs, I2 at ~7, I3 at ~8 ('smooth mouth' at 9).
• Galvayne's groove may appear near 10 years, extend approximately halfway by 15 and along the tooth by 20, but its timing is variable and must not be used as an exact age determination.

AGE DETERMINATION (Dog):
Deciduous teeth erupt 3-6 weeks. Permanent: incisors at 3-5 months, canines at 5-6 months, premolars 4-6 months, molars 5-7 months. After 1 year — wear pattern of incisor cusps (cusps level by 4-5 yrs).