# Aetiological relevance of haematological, biochemical and endocrine parameters on equine odontoclastic tooth resorption and hypercementosis (EOTRH)

## TL;DR

This study investigates blood and hormone differences in horses with EOTRH, a painful dental disease, to identify possible risk factors and underlying causes.

## Contribution

The study is the first to compare haematological, biochemical, and endocrine parameters in EOTRH-affected and non-affected horses.

## Key findings

- Selenium deficiency and low vitamin D levels were common in all horses, regardless of EOTRH status.
- No significant differences in blood cell counts or thyroid function were found between EOTRH-affected and non-affected horses.
- Pituitary pars intermedia dysfunction was present in 17% of the horses, but no strong correlation with EOTRH was established.

## Abstract

The dental syndrome EOTRH is a painful, progressive dental disease with an unknown aetiology. The often painful nature of EOTRH emphasises the need for a better knowledge of the underlying pathogenic mechanism and risk factors. A comparative analysis of haematological, biochemical and endocrine values in EOTRH‐affected and non‐affected horses has not been described.

To compare haematological, biochemical, and endocrine parameters in EOTRH‐affected and non‐affected horses to detect risk factors for horses developing EOTRH.

Cross sectional.

Blood samples of 154 Icelandic horses aged 15 years and older were collected. A CBC, biochemistry panel, and endocrine profile were performed. A detailed examination of the rostral oral cavity was performed, and incisors were evaluated radiographically using a standardised scoring system. Based on the results, the study population was separated into ‘EOTRH‐affected’ (n = 109) and ‘EOTRH‐nonaffected’ (n = 23) horses. A staging system enabled further differentiation into mild (Stage 2), moderate (Stage 3) or severe (Stage 4) EOTRH‐affected versus Stage 0 (EOTRH‐nonaffected). To assess the correlations between EOTRH diagnosis and the measured parameters, logistic regression analysis was performed.

No consistent abnormalities were detected in the CBC. In the biochemistry panel, selenium deficiency (38%) and hypovitaminosis D (83%) were the only consistent abnormalities observed across the entire study population. Endocrine analytes showed no abnormalities in thyroid function. Pituitary pars intermedia dysfunction was diagnosed in 17% of the horses.

Irregular distribution of horses between the control group and the EOTRH‐affected group. Plasma concentrations were measured only once, and no functional tests of the thyroid gland, nor an oral sugar test or TRH stimulation test were performed.

EOTRH triggers a predominantly local inflammation in the oral cavity, without measurable changes in the inflammatory cells or significant variations in plasma vitamin and trace element serum concentrations.