Veterinary radiology & ultrasound : the official journal of the American College of Veterinary Radiology and the International Veterinary Radiology Association2026; 67(5); e70235; doi: 10.1111/vru.70235

Scintigraphic Characteristics of the Occipitoatlantoaxial Region in Clinically Sound Horses.

Mageed, M
·
Podsobińska, M
·
Przewoźny, M

Abstract: The equine occipitoatlantoaxial (OAA) region is biomechanically complex, yet normative scintigraphic reference data for this area are lacking. This retrospective study characterized the physiological radiopharmaceutical uptake pattern in the OAA region of 60 clinically sound horses, assigned equally into four age groups: under 6 years (Group A), 6-10 years (Group B), 11-15 years (Group C), and over 15 years (Group D). A standardized, semiquantitative analysis of lateral bone-phase scintigrams was performed using region of interest (ROI) ratios to determine uptake patterns. A highly consistent pattern was observed across all groups, with the atlantoaxial region (cranial C2) demonstrating the highest uptake, approximately 5.8 times greater (SD 1.93; 95% CI: [5.6-6.6]) than the lowest uptake in the atlanto-occipital region. While age had no significant overall effect on the pattern, Group C (11-15 years) showed slightly higher uptake in the ventral atlas (ROI vC1) and cranial axis (ROI C2) compared to other groups. This study provides the first detailed baseline of normal OAA scintigraphic appearance across a representative age range, establishing essential reference data to improve diagnostic accuracy for cervical pathology in clinical practice.

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Publication Date: 2026-09-17 PubMed ID: 42751976DOI: 10.1111/vru.70235Google Scholar: Lookup

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Journal Article

Summary

This research summary has been generated with artificial intelligence and may contain errors and omissions. Refer to the original study to confirm details provided. Submit correction.

Objective Overview

This study aimed to establish normative reference data for scintigraphic (bone scan) patterns in the occipitoatlantoaxial (OAA) region of the horse’s neck, to better understand normal physiological radiopharmaceutical uptake in clinically healthy horses across different age groups.

Background

The occipitoatlantoaxial (OAA) region, comprising the occiput, atlas (C1), and axis (C2) vertebrae, is a biomechanically complex area crucial for head and neck movement in horses.
There was previously no detailed baseline data describing normal scintigraphic uptake patterns in this region, which is important for distinguishing healthy tissue from pathology in clinical scintigraphy.
Scintigraphy involves injecting a radiopharmaceutical and imaging its uptake, which reflects bone metabolic activity, making it useful to detect abnormalities such as bone inflammation or remodeling.

Study Design

A retrospective study was conducted on 60 clinically sound (healthy) horses.
Horses were divided into four equal groups based on age: <6 years (Group A), 6-10 years (Group B), 11-15 years (Group C), and >15 years (Group D).
Lateral bone-phase scintigrams (side-view bone scans) of the OAA region were collected and analyzed.
A standardized semiquantitative approach was used, focusing on regions of interest (ROIs) within the OAA area to measure radiopharmaceutical uptake ratios.

Key Findings

A highly consistent pattern of radiopharmaceutical uptake was observed across all age groups.
The atlantoaxial region (cranial part of C2 vertebra) showed the highest physiological uptake, approximately 5.8 times greater than the region with the lowest uptake (atlanto-occipital region).
This suggests higher metabolic or bone activity in the cranial C2 area compared to other parts of this region in healthy horses.
Age did not significantly affect the overall pattern of uptake.
However, horses aged 11-15 years (Group C) showed slightly higher uptake in the ventral atlas (ventral part of C1) and cranial axis (C2), possibly indicating subtle age-related changes or remodeling in this middle age group.

Clinical Significance

The study establishes the first detailed baseline scintigraphic reference data for the equine OAA region, which can be used in clinical practice to differentiate normal from abnormal findings.
By understanding the typical physiological uptake patterns in healthy horses, veterinarians can improve diagnostic accuracy when evaluating cervical spine diseases or trauma.
This baseline helps avoid false positives or misinterpretations of uptake patterns that might be mistaken for pathology but represent normal variation.

Conclusion

This research fills an important gap by providing normative scintigraphic characteristics of the equine OAA region across a representative age range.
The findings help guide interpretation of bone scintigraphy in horses, facilitating better diagnosis and management of cervical spine conditions.

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APA

Mageed M, Podsobińska M, Przewoźny M. (2026). Scintigraphic Characteristics of the Occipitoatlantoaxial Region in Clinically Sound Horses. Vet Radiol Ultrasound, 67(5), e70235. https://doi.org/10.1111/vru.70235

Publication

Veterinary radiology & ultrasound : the official journal of the American College of Veterinary Radiology and the International Veterinary Radiology Association

ISSN: 1740-8261

NlmUniqueID: 9209635

Country: England

Language: English

Volume: 67

Issue: 5

Pages: e70235

Researcher Affiliations

Mageed, Mahmoud

Equipixel Veterinary Teleradiology, Bakum, Germany.

Podsobińska, Magdalena

Dechra Veterinary Products Sp. z O.O., Warszawa, Poland.

Przewoźny, Maciej

Equi Vet Serwis Klinika dla Koni Sp. z o.o, Buk, Poland.

MeSH Terms

Animals
Horses / anatomy & histology
Radionuclide Imaging / veterinary
Retrospective Studies
Female
Radiopharmaceuticals
Male
Atlanto-Axial Joint / diagnostic imaging
Atlanto-Occipital Joint / diagnostic imaging
Reference Values

References

This article includes 22 references

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