Multi-disease panel aimed at the Nova Scotia Duck Tolling Retriever that groups tests for hereditary conditions with a molecular test available in the breed or in related breeds: collie eye anomaly (CEA), prcd progressive retinal atrophy (prcd-PRA), chondrodysplasia/chondrodystrophy with risk of disc herniation (CDPA and CDDY), cerebellar degeneration and myositis (CDMC) and cleft lip/cleft palate with syndactyly (CLPS). The panel allows ocular, musculoskeletal and craniofacial conditions to be managed in a single sample. The IVDD risk linked to CDDY makes it necessary to combine genotyping with weight and exercise management.

Applicable breed: Nova Scotia Duck Tolling Retriever. CDMC: estimated allele frequency of 3.6% (European population) and 1.3% (North American), with carriers at 7.1% and 2.7% (Christen et al. 2022). The population frequency of carriers of the ADAMTS20 deletion (CLPS) is not well characterized, and for CEA, prcd-PRA and CDPA/CDDY no systematic figures are available in the breed (limited data).

- Fundus abnormalities: choroidal hypoplasia (CEA)\n- Reduced night vision and progressive retinal atrophy (prcd-PRA)\n- Shortened limbs (CDPA) and chondrodystrophy phenotype (CDDY)\n- Disc herniation and lower back pain/early neurological weakness (IVDD risk of CDDY)\n- Cerebellar ataxia and progressive muscle weakness (CDMC)\n- Cleft lip/cleft palate and digital fusion (syndactyly) (CLPS)

The panel tests were developed independently. CEA was associated with a deletion in NHEJ1 on CFA37 (Parker et al. 2007). prcd-PRA was associated with the PRCD gene (Zangerl et al. 2006). Chondrodystrophy and its risk of disc herniation were linked to an insertion of the FGF4 retrogen on CFA12 (Brown et al. 2017), and chondrodysplasia to an equivalent insertion on CFA18 (Parker et al. 2009). The cerebellar degeneration and myositis complex (CDMC) of the Toller was associated with a missense variant in SLC25A12 (Christen et al. 2022) and the cleft lip/palate and syndactyly syndrome (CLPS) with a deletion in ADAMTS20 (Wolf et al. 2015).

- Genotype breeding animals before mating.\n- Recessives (CEA, prcd-PRA, CDMC and CLPS): do not mate two carriers (25% homozygotes per litter); carrier × clear does not produce affected animals.\n- CDPA/CDDY: avoid accumulating CDDY alleles (IVDD risk); mating CDDY carriers with clear animals reduces the disc risk.\n- CLPS: exclude affected homozygotes from breeding; consider prenatal ultrasound in risk lines.\n- After a confirmed clinical case, do not repeat the parental mating and communicate the status to the buyer.

Annual ocular examination (ECVO) complementary. Weight management and controlled exercise in CDDY carriers to reduce IVDD risk; monitor for signs of disc herniation (lower back pain, weakness). CLPS requires early surgical assessment in affected puppies. Differentiate CDMC from other hereditary ataxias by age of onset and MRI. Mild CEA may go unnoticed without fundus examination.

1. Parker HG et al. 2007, deleción de 7,8 kb que cosegrega con la anomalía ocular del Collie en múltiples razas (Genome Res) (PMID 17916641).
2. Zangerl B et al. 2006, mutación idéntica en un gen retiniano novel que causa prcd en perros (Genomics) (PMID 16938425).
3. Brown EA et al. 2017, el retrogén FGF4 en CFA12 es responsable de la condrodistrofia y la enfermedad del disco intervertebral en perros (PNAS) (PMID 29073074).
4. Christen M et al. 2022, variante missense de SLC25A12 en el complejo degeneración cerebelosa-miositis del Toller (Genes Basel) (PMID 35886006).
5. Wolf ZT et al. 2015, ADAMTS20 como variante de riesgo de labio y paladar hendido en perros y humanos (PLoS Genet) (PMID 25798845).
6. Parker HG et al. 2009, el retrogen fgf4 expresado se asocia a la condrodisplasia definitoria de raza en perros (Science) (PMID 19608863).
7. OMIA:000218-9615, OMIA:002294-9615, OMIA:001140-9615.