**Introduction**
The signature feature of the Scottish Fold breed of cats are folded ears. This phenotype is the result of a single dominant TRPV4 gene variant. Pioneering work by Jackson [(1974)][1] reported that cats carrying two copies of this gene (homozygous) were crippled and exhibited skeletal lesions that could be observed on radiographs, while heterozygous cats appeared healthy. Subsequent work by Malik et al. ([1999][2]) suggests that heterozygous cats may also have behavioral impairments and radiological signs, referred to as Scottish Fold Osteochondrodysplasia (SFOCD). However, that study had several limitations including selection bias (most cats included due to behavioral issues), lack of genetic data (so it is possible some cats were heterozygous) and lack of control cats with blinded radiolgical reading.
This Open Science Framework project provides the radiographic images from a study designed to address these limitations. Specifically, X-Rays from 22 cats (10 with folded-ears). The provided ratings were conducted reviewers blind to each cat's phenotype. The images are now provided publicly in unblinded form. The images may provide a good training set for determining the distinctive features of SFOCD. Retrospective review of this training dataset may guide better detection SFOCD. These images also provide clinicians examples of the subtle issues can be observed in heterozygous cats, which are much harder to identify than the extreme abnormalities previously published.
A manuscript is currently under review which provides more details as well as the results of blinded rating of these scans. Details regarding this publication will be provided here once that work is accepted.
**Figure 1:** Example of radiograph from folded ear cat (15827) where a blind reviewer commented: ‘Note the loss of joint spaces and the irregular periosteal new bone formation on the cranial and caudal aspects of the hock joint’
![Example of radiograph from folded ear cat (15827)][6]
**Methods**
22 cats were scanned. Genetics were consistent with the phenotype of each cat and ensures that no homozygous (FdFd) folded-ear cats were included in this sample. The 12 straight-eared cats had two copies of the normal wild variant TRPV4 (fdfd), while 10 folded ear cats were heterozygous (Fdfd). Two lateral scans were acquired for each cat, focusing on the hindlimbs on the left and right side.
Data was sequentially acquired on a Sound SmartDR system. The images used the diagnostic quality X-Ray dose exposure. Data was acquired in a pseudo-random order. The images are provided in DICOM format with the JPEG2000-lossless transfer syntax. These images provided 16-bit dynamic range, allowing raters to optimize the contrast and brightness (window width and center). These images can be viewed with free tools like the web-based [iamios][4] or [Horos][5] for macOS.
Four independent raters with experience in radiology (KB, GK, RM, RR) were asked to blindly rate each cat. We refer to these raters with the randomized identifier 'A', 'B', 'C' and 'D'. They were told the age and gender of each cat, but were not told the phenotype. They were explicitly told not to assume equal numbers of folded-ear and straight-ear cats (as fixed marginals reduce statistical power, an important consideration in small studies). For each cat they were asked to guess if the cat was a folded-ear cat (* in table) and provide a SFOCD severity score in the range of 1 (normal) to 5 (severe). Since no graded SFOCD rating scale exists, each rater was allowed to come up with their own definition for this 5-point scale.
| ID | Fdfd | Age (Months) | Rater A | Rater B | Rater C | Rater D |
| -- | ---- | ------------ | ------- | ------- | ------- | ------- |
| 15822 | No | 81 | 1 | 2 | 1 | 1 |
| 15824 | No | 73♂ | 1.5 | 1 | 1 | 1 |
| 15828 | No | 59 | 2.5 | 2 | 1 | 1 |
| 15830 | No | 45 | 1.5 | 1 | 2 | 1 |
| 15832 | No | 41 | 1 | 2 | 2 | 1 |
| 15833 | No | 29 | 1 | 1 | 2 | 1 |
| 15835 | No | 38 | 1 | 2 | 1 | 1 |
| 15836 | No | 32♂ | 1.5 | 2 | 3 | 2 |
| 15838 | No | 19 | 1 | 1 | 2 | 1 |
| 15839 | No | 21 | 1.5 | 1 | 2.5 | 1 |
| 15841 | No | 16♂ | 1.5 | 2 | 2 | 2 |
| 15842 | No | 11 | 1 | 2 | 2 | 1 |
| 15821 | Yes | 81 | 2 | 3 | 3.5 | 1 |
| 15823 | Yes | 71♂ | 1.5 | 3 | 1 | 1 |
| 15825 | Yes | 66 | 2 | 2 | 3 | 1 |
| 15826 | Yes | 66♂ | 2.5 | 5 | 4 | 2 |
| 15827 | Yes | 59 | 3 | 5 | 3.5 | 2 |
| 15829 | Yes | 42 | 3 | 4 | 4.5 | 1 |
| 15831 | Yes | 41 | 2 | 2 | 3 | 1 |
| 15834 | Yes | 37 | 2 | 3 | 4 | 2 |
| 15837 | Yes | 32 | 2 | 3 | 3.5 | 2 |
| 15840 | Yes | 17♂ | 2 | 2 | 3 | 1 |
[1]: https://scholar.google.com/scholar_lookup?title=Congenital%20bone%20lesion%20in%20cats%20with%20folded-ears&publication_year=1975&author=O.F.%20Jackson
[2]: https://pubmed.ncbi.nlm.nih.gov/10078353/
[3]: https://mfr.osf.io/export?url=https://osf.io/pygke/?direct&mode=render&action=download&public_file=True&initialWidth=848&childId=mfrIframe&parentTitle=OSF%20%7C%2015827.png&parentUrl=https://osf.io/pygke/&format=2400x2400.jpeg
[4]: https://www.imaios.com/en/Imaios-Dicom-Viewer
[5]: https://horosproject.org
[6]: https://files.osf.io/v1/resources/n59eh/providers/osfstorage/606c50b4f2ad33021da768aa?mode=render
