🦷 Age by Teeth

A sourced age range from the permanent incisors of cattle, sheep and goats

SPECIES

Front view with the lower lip pulled down. You can also click a tooth.

ERUPTED PERMANENT INCISORS
WEAR IN A FULL MOUTH
Milk tooth — small, white Permanent tooth — large, broad Dental pad — no upper incisors Wear surface — exposed dentine
Estimated age range
19–38 months
about 1.6 – 3.2 years
Confidence: within the eruption window

Pair 1 erupts at 19–32 months (UF CIR253 · Merck · Dodt & O'Rourke 1988 · Kikule 1953). Pair 2 has not erupted yet; it erupts at 25–38 months (Merck · Dodt & O'Rourke 1988 · Kikule 1953).

USDA FSIS 30-month rule The second pair of permanent incisors has not erupted: by dentition alone, FSIS does not classify the animal as 30 months or older. FSIS Directive 6100.4
VetKriter Brain — Expert comment

What this result means

Pair 1 has erupted and pair 2 has not. The lower end of the range belongs to early erupters, the upper end to late ones. In cattle the spread comes mainly from breed and sex: on the same pasture Shorthorn steers cut every pair earlier than Brahman crosses (Dodt & O'Rourke 1988), and females erupt later than steers (Carles & Lampkin 1977).

How to narrow the range

  • Pair 2 erupts at 25–38 months (Merck · Dodt & O'Rourke 1988 · Kikule 1953). Re-examine the animal every few months; the moment you see that pair erupt, the age drops into that window.
  • If you know the animal's breed and the conditions it was raised in, judge which end of the range it sits closer to.

When you decide

If the range looks wide, that is the real uncertainty of the method; a narrower one would mean ignoring part of the sources. Ear tags and records remain the basis for an exact age.

The tool does not give a single age, a birth date or a legal document. After a full mouth, age can only be judged from wear and becomes much less reliable.

When the permanent incisors erupt

Cattle
Pair Eruption window Source
Pair 1 (central) 19–32 months UF CIR253 · Merck · Dodt & O'Rourke 1988 · Kikule 1953
Pair 2 25–38 months Merck · Dodt & O'Rourke 1988 · Kikule 1953
Pair 3 31–47 months Merck · Dodt & O'Rourke 1988 · Kikule 1953
Pair 4 (corner) 38–58 months UF CIR253 · Merck · Dodt & O'Rourke 1988 · Kikule 1953
Sheep
Pair Eruption window Source
Pair 1 (central) 12–20 months Merck · Wilson & Durkin 1984 · Cocquyt 2005
Pair 2 18–26 months Merck · Wilson & Durkin 1984 · Cocquyt 2005, 96% of animals
Pair 3 24–36 months Merck · Wilson & Durkin 1984 · Cocquyt 2005, 92% of animals
Pair 4 (corner) 30–48 months Merck · Wilson & Durkin 1984 · Cocquyt 2005, 96% of animals
Goat
Pair Eruption window Source
Pair 1 (central) 12–18 months LSU · Merck · Wilson & Durkin 1984
Pair 2 18–24 months LSU · Merck · Wilson & Durkin 1984
Pair 3 24–36 months LSU · Merck · Wilson & Durkin 1984
Pair 4 (corner) 30–48 months Merck · Wilson & Durkin 1984 · LSU

Each window spans the earliest and latest observations in the verified sources; differences between sources are not hidden. Eruption can be clearly later in zebu and crossbred cattle and under range conditions (Dodt & O'Rourke 1988; Kikule 1953); in light animals the first permanent pair can be up to 3 months later (McGregor & Butler 2011).

How to check the mouth

  1. Restrain the animal safely and wear gloves.
  2. Pull the lower lip down to see the lower incisors. There are no upper incisors, only a hard dental pad.
  3. Count from the centre outwards: large, broad, cream-coloured teeth are permanent; small white teeth are milk teeth.
  4. Select the number of erupted permanent pairs above. Count a pair as erupted as soon as at least one of its teeth has broken through the gum; the ranges were measured with this definition (Dodt & O'Rourke 1988). If the gum is still red and swollen, the tooth has erupted recently; this sign disappears within two months (Cocquyt et al. 2005).

Frequently Asked Questions

Look at the eight incisors of the lower jaw; there are no upper incisors, only a dental pad. Milk teeth are small and white, permanent teeth are clearly larger and broader. Permanent incisors erupt in pairs from the centre outwards; the number of erupted permanent pairs gives an age range.

2-tooth: 12–26 months · 4-tooth: 18–36 months · 6-tooth: 24–48 months · Full mouth: ≥ 30 months (Merck; Wilson & Durkin 1984; Cocquyt et al. 2005). Breed, nutrition and environment can shift eruption by about 6 months (NMSU B-412).

2-tooth: 19–38 months · 4-tooth: 25–47 months · 6-tooth: 31–58 months · Full mouth: ≥ 38 months. Eruption is clearly later in zebu and crossbred cattle (Dodt & O'Rourke 1988; Kikule 1953). In well-fed beef cattle all incisors are in wear at about 4½ years; after that, age can only be judged from wear, and beyond 8 years it is very difficult (UF CIR253).

2-tooth: 12–24 months · 4-tooth: 18–36 months · 6-tooth: 24–48 months · Full mouth: ≥ 30 months. It is difficult to age goats over four years old (LSU).

No, only a range. In a study that followed 176 sheep for a year, 22 had no permanent incisor erupt that year and 18 erupted asymmetrically (Cocquyt et al. 2005). Ear tags and records are the basis for an exact age.

Scientific References

  1. Wright A (reviewed by Carnevale J). Estimation of Age by Examination of the Teeth in Animals. Merck Veterinary Manual, revised July 2026.
  2. Cocquyt G, Driessen B, Simoens P (2005). Variability in the eruption of the permanent incisor teeth in sheep. Veterinary Record 157:619–623. doi:10.1136/vr.157.20.619
  3. Pace JE, Wakeman DL. Determining the Age of Cattle by Their Teeth (CIR253). University of Florida IFAS Extension, 1983 (reviewed 2003).
  4. Dodt RM, O'Rourke PK (1988). Dentition in beef cattle in northern Australia. Queensland Journal of Agricultural and Animal Sciences 45(1):53–56.
  5. Kikule SB (1953). Age changes in the teeth of zebu cattle. East African Agricultural Journal 19(2):86–88. doi:10.1080/03670074.1953.11664882 (eruption ranges cited from ILCA 1990)
  6. Wilson RT, Durkin JW (1984). Age at permanent incisor eruption in indigenous goats and sheep in semi-arid Africa. Livestock Production Science 11(4):451–455. doi:10.1016/0301-6226(84)90056-3
  7. McGregor BA, Butler KL (2011). Determinants of permanent first incisor eruption in grazing Australian Angora goats. Australian Veterinary Journal 89(12):490–495. doi:10.1111/j.1751-0813.2011.00842.x
  8. ILCA (1990). Livestock systems research manual, Vol. 1 (Working Paper 1), Table 10. International Livestock Centre for Africa, Addis Ababa. (not peer-reviewed)
  9. Pitassi S, Hernandez Gifford JA, Gifford C, Ward M (2022). Sheep Production: Age Identification, Guide B-412. New Mexico State University. pubs.nmsu.edu
  10. Johnson R (2015). Aging Goats by Mouthing. Animal Industry News Update 16(3), LSU AgCenter.
  11. Regulation (EC) No 999/2001, Annex V (specified risk material), as amended.
  12. USDA FSIS Directive 6100.4 — verification of 30 months of age by dentition.
  13. Din İşleri Yüksek Kurulu. Kurbanlık hayvanların yaşlarında aranacak olan asgari sınır nedir? kurul.diyanet.gov.tr
  14. WikiVet. Dental Formula – Ruminants (I0/3 C0/1). en.wikivet.net

The corner (4th) pair is anatomically an incisiform canine; in the field it is counted as the 4th incisor.

Guide: How to age cattle, sheep and goats by their teeth
Source tables, the effect of breed and nutrition, examination details and the full reference list are in the guide.
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