Pilot study of head conformation changes over time in the Cavalier King Charles spaniel breed

• https://veterinaryrecord.bmj.com/content/184/4/122.full

Breed Specific: Cavalier King Charles Spaniel: Conformation Traits/SM|CM

Knowler, SP., Gillstedt, L., Mitchell, TJ., Jovanovik, J., Volk, HA., Rusbridge, C.   (2019) Pilot study of head conformation changes over time in the Cavalier King Charles spaniel breed    Veterinary Record 184, 122.

Abstract

Modern interpretation of head conformation in the Cavalier King Charles spaniel (CKCS) has favoured a smaller, more exaggerated, brachycephalic type than originally described in the 1929 breed standard. Recent research studies identified brachycephaly and reduced hind cranium as two conformational (dysmorphic) features that increase risk for symptomatic Chiari-like malformation and secondary syringomyelia (SM). A prospective pilot study investigated the hypothesis that dysmorphic head features could be assessed visually and correlated with risk of SM. Thirteen CKCS, selected from anonymised photographic evidence, were physically appraised by authorised Kennel Club judges using a head shape checklist. These subjective evaluations were then matched with objective measurements of the cranium (cephalic index and rostrocaudal doming) and their subsequent MRI. A positive correlation (P=0.039) between the judges’ checklist score and rostrocaudal doming (hindskull ratio) and a positive correlation between the cephalic index and hindskull ratio (P=0.042) were identified. Five CKCS had no SM and their status tallied with 62 per cent of the judges’ evaluation. Although the ability of adjudicators to identify differences in head conformation varied, there was sufficient association between the dysmorphic parameters and the risk of SM to cause concern and propose a larger study in CKCS breed.

Breeder viewpoint:

This research paper is a readily understandable PILOT study that covers how head shapes relate to scientific information on SM/CM in Cavaliers. Which skull shapes represent identifiable extremes and can/should anything be done to curtail the drift towards hypertype over the past few decades? Which direction do the breed enthusiasts want to go?   In the Discussion section, "breeders have acknowledged that there has been a more brachycephalic interpretation of the breed standard over the last few decades."  Further, " The concept that increased exaggeration of head shape in the CKCS can be recognised visually and supported by the proven association of brachycephaly with resulting rostrocaudal doming5 suggests the possibility for selection against the extreme head shape in the CKCS to enable a reduction in CM/SM incidence."

Take a look at this study for photos that represent different shapes and measurements of CKCS head type/backskulls. Maybe it's worth considering the information offered when choosing dogs for showing and breeding. Yes, it's a small study - and yes, there is some variation in interpretation of the degree to which dogs viewed are visibly extreme,  and, there are Limitations to the study that are outlined by the researchers. But given the possible relationship between squished backskulls and their potential association with SM/CM  and its impact on the quality of life for dogs - maybe this research is worth a glance for breeders and for judges. Lots of illustrations and pictures were helpful. 

Breed Advisor viewpoint:

Veterinary Epidemiologist viewpoint: