Histologic assessment of age-related changes in the temporomandibular joints of horses.

The study investigates the age-related changes in the temporomandibular joints (TMJs) of horses, observing that as horses age, lesions associated with osteoarthritis accumulate.

Objective and Methods

• This detailed study involved the examination of temporomandibular joints from 11 deceased horses divided into varying age groups. The groups were assigned as follows: group 1 consisted of horses aged 2 to 10 years, group 2 was from 11 to 20 years, and group 3 comprised horses older than 20 years.
• Each TMJ was cut into pieces of 5-mm thickness, preserved with formalin, decalcified using formic acid, and eventually prepared for histological (tissue structure-related) analysis. The study utilized multilevel mixed-effects models for scrutinizing the collected data and its patterns.

Results

• The findings demonstrated a correlation between the age of the horses and the conditions of their TMJs. Younger horses (group 1) showed significantly fewer and less severe changes in their TMJs when compared with the oldest group (group 3).
• The aggregate of temporal and mandibular scores was lowest for group 1, followed by groups 2 and 3. Differences were also observed in the disk scores among the groups, with group 3 having the highest disk score.

Conclusions

• The study concluded that the TMJ lesions earmarked for the study were commonly related to osteoarthritis, which increased with the advancing age of the horses.
• However, without observable signs of pain which reflect alterations in mastication, behavior, or performance, it is challenging to determine the precise moment when these accrued pathological changes start to characterize clinically significant osteoarthritis in the TMJs of the horses.