Geometric Morphometric Analysis of Nasal and Orbital Regions in Mesocephalic Dogs: A Comparative Assessment Based on Climatic Origin

Abstract

The nasal and orbital regions, in particular, exhibit remarkable variations in both respiratory functions and facial morphology. This study conducted a descriptive investigation of how morphological features in the nasal and orbital regions of mesocephalic dogs vary among individuals across different climates. This study does not aim to test the direct effect of climate on cranial morphology, but rather to evaluate whether a climate-based grouping of dog breeds corresponds to measurable shape variation. The skulls of 31 breeds were used in the study. Dogs were grouped according to whether they lived in harsh (n: 13), moderate (n: 11) and warm (n: 7) climates. The skulls were modeled using three-dimensional images provided by Kubinyi et al. (2024). 20 landmarks were marked in the nasal region (apertura nasalis ossea) and 22 in the left orbital region. The MorphoJ program was used. As a result of the PCA, it was observed that warm-climate dogs were partially separated according to the PC1 distribution graph. According to cross-validation scores, although not statistically significant, the harsh and warm climate dogs were correctly grouped with a high percentage (75%). The study reveals that there are certain morphological shape differences between different climate groups, and these differences show a remarkable trend towards climate-based separation. However, these differences are not at a level that would create a statistically significant separation. This situation points to a potential effect of climate on cranial shape variation, but suggests that the observed variation is largely related to breed-specific morphological characteristics.

Keywords

• Eye
• nose
• sense
• warm

Ethical Statement

This study was approved by the Dokuz Eylül University Animal Experiments Local Ethics Committee (Date: 14.05.2025, Protocol number 12/25). In addition, the authors declared that Research and Publication Ethical rules were followed.

Thanks

This article was presented as a poster at the 13th National, 4th International Veterinary Anatomy Congress (September 25-28, 2025, Balıkesir / Türkiye).

Mezosefalik Köpeklerde Os Nasale ve Orbita Çevresi Bölgelerinin Geometrik Morfometrik Analizi: İklimsel Kökene Dayalı Karşılaştırmalı Bir Değerlendirme

Abstract

Köpek kafatası morfolojisi, ırk, seçilim, fonksiyonel kullanım ve çevresel koşullar da dahil olmak üzere birçok faktörden etkilenir. Özellikle burun ve göz çevresi bölgeleri, hem solunum fonksiyonlarında hem de yüz morfolojisinde dikkat çekici farklılıklar gösterir. Bu çalışma, mezosefalik köpeklerin burun ve göz çevresi bölgelerindeki morfolojik özelliklerin farklı iklimlerden gelen bireyler arasında nasıl değiştiğini tanımlayıcı bir şekilde araştırmıştır. Bu çalışma, iklimin kranial morfoloji üzerindeki doğrudan etkisini test etmeyi değil, iklime dayalı bir köpek ırkı gruplandırmasının ölçülebilir şekil varyasyonuna karşılık gelip gelmediğini değerlendirmeyi amaçlamaktadır. Çalışmada 31 ırkın kafatası kullanılmıştır. Köpekler, sert (n: 13), ılıman (n: 11) ve sıcak (n: 7) iklimlerde yaşayıp yaşamadıklarına göre gruplandırılmıştır. Kafatasları, Kubinyi vd. (2024) tarafından sağlanan üç boyutlu görüntüler kullanılarak modellenmiştir. Burun bölgesinde (apertura nasalis ossea) 20 ve sol göz çevresi bölgesinde 22 işaret noktası belirlenmiştir. MorphoJ programı kullanılmıştır. PCA sonucunda, sıcak iklim köpeklerinin PC1 dağılım grafiğine göre kısmen ayrıldığı gözlemlenmiştir. Çapraz doğrulama puanlarına göre, istatistiksel olarak anlamlı olmasa da, sert ve sıcak iklim köpekleri yüksek bir oranda (%75) doğru şekilde gruplandırılmıştır. Çalışma, farklı iklim grupları arasında belirli morfolojik şekil farklılıkları olduğunu ve bu farklılıkların iklime dayalı ayrışmaya doğru dikkat çekici bir eğilim gösterdiğini ortaya koymaktadır. Bununla birlikte, bu farklılıklar istatistiksel olarak anlamlı bir ayrışma yaratacak düzeyde değildir. Bu durum, iklimin kranial şekil varyasyonu üzerindeki potansiyel etkisine işaret etmekle birlikte, gözlemlenen varyasyonun büyük ölçüde ırka özgü morfolojik özelliklerle ilgili olduğunu düşündürmektedir.

Keywords

• göz
• burun
• duyu
• sıcaklık

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