Peer-reviewed veterinary case report
Extreme flat-faced shape linked to skull gaps in adult Chihuahuas
By Rautala, Elina et al.·Published in Journal of veterinary internal medicine·2025·Department of Equine and Small Animal Medicine·View original on PubMed →
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Original publication title: Association of Extreme Brachycephaly With Persistent Fontanelles in Adult Chihuahuas.
- Species:
- dog
Plain-English summary
A study looked at 50 adult Chihuahuas and found that those with more extreme head shapes (brachycephaly) often had larger areas of persistent fontanelles, which are soft spots on the skull that usually close as dogs mature. The research showed that Chihuahuas with these head shapes tended to weigh less. This means that if you have a Chihuahua with a very flat face and noticeable soft spots on their head, it might be linked to their body weight and head shape. If you're concerned about your Chihuahua's head shape or soft spots, it's a good idea to discuss this with your veterinarian.
Abstract
BACKGROUND: Although persistent fontanelles (PFs) are common in adult Chihuahuas, their association with cranial morphology remains unknown. OBJECTIVES: To identify whether cranial morphology is associated with PFs in Chihuahuas and if bodyweight is associated with cranial morphology in this breed. ANIMALS: Fifty client-owned Chihuahuas. METHODS: In this retrospective cross-sectional study using computed tomography images, we measured two different cranial base lengths (1 and 2), cranial length, height, and width, and two craniofacial angles. We calculated the ratios of cranial height to cranial base lengths 1 and 2, cranial height to length, cranial height to width, and cranial width to length (cranial index [CrI]). We evaluated if total PF area and number of cranial sutures affected by PFs were associated with craniometric measurements and their ratios and craniofacial angles. Additionally, we evaluated if the craniometric ratios were associated with bodyweight. RESULTS: Total PF area was larger and number of cranial sutures affected by PFs higher in dogs with higher cranial height to cranial base length ratios 1 (estimate, [95% confidence interval], p: 2.295, [1.204-4.377], p = 0.01 and 1.720, [1.212-2.442], p = 0.002, respectively) and 2 (1.203, [1.069-1.354], p = 0.003 and 1.087, [1.011-1.169], p = 0.02, respectively) and CrI (1.225, [1.079-1.391], p = 0.002, and 1.134, [1.057-1.215], p < 0.001, respectively). Higher CrI was associated with lower bodyweight (-2.600, [-4.102 to -1.098], p = 0.001). CONCLUSION AND CLINICAL IMPORTANCE: Our results suggest that in Chihuahuas, lower bodyweight is associated with more extreme brachycephaly and extreme brachycephaly is associated with PFs.
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Search related cases →Original publication on PubMed: https://pubmed.ncbi.nlm.nih.gov/39968731/