Multi-disease panel aimed at the Chesapeake Bay Retriever that groups three tests for hereditary conditions described in the breed: prcd-PRA progressive retinal atrophy, exercise-induced collapse (EIC) and degenerative myelopathy (DM exon 2). The panel allows ocular, exertional neuromuscular and degenerative neurological conditions to be managed in a single sample. EIC requires modifying exercise routines and DM has incomplete penetrance.

Applicable breed: Chesapeake Bay Retriever. EIC is described in the Chesapeake Bay Retriever (Patterson 2008). DM due to SOD1 exon 2 is present in many breeds. prcd-PRA is documented in retriever breeds. There are no breed-specific carrier estimates (limited data).

- Reduced night vision and progressive retinal atrophy (prcd-PRA)\n- Muscle collapse after intense exercise (EIC): hindlimb weakness, ataxia, recovery within a few minutes\n- Progressive paresis of thoracic and pelvic limbs with proprioceptive ataxia (DM)

The panel tests were developed independently. prcd-PRA was associated with the PRCD gene. EIC was associated with a variant in DNM1 (dynamin-1) described in retriever breeds. Canine DM was associated with the SOD1 exon 2 variant based on the work of Awano and colleagues in 2009.

- Genotype breeding animals before mating; the panel covers three conditions on a single sample\n- prcd-PRA, EIC and DM (recessive): do not mate carrier×carrier (25 % of affected homozygotes); carrier×clear produces no affected animals and gives 50 % carriers\n- In animals with a risk genotype for EIC, adjust exercise routines (avoid sustained intense exertion, heat and excitement)\n- In DM, remember that a homozygote will not necessarily develop the condition (incomplete penetrance)\n- After a confirmed clinical case, do not repeat the parental mating and inform the buyer of the status

Complementary annual ocular examination (ECVO). EIC is a diagnosis of exclusion: rule out myopathies, cardiopathies and orthopaedic conditions before attributing the collapse to DNM1; the episodes are triggered by sustained intense exercise and excitement. DM is a diagnosis of exclusion: rule out spinal cord compression, disc herniation and neoplasia before attributing the condition to SOD1. Differentiate EIC collapse from the exercise-induced collapse syndrome of other breeds.

1. Zangerl B et al. Identical mutation in a novel retinal gene causes progressive rod-cone degeneration in dogs and retinitis pigmentosa in humans. Genomics. 2006;88(5):551-563. PMID: 16938425.
2. Patterson EE et al. A canine DNM1 mutation is highly associated with the syndrome of exercise-induced collapse. Nat Genet. 2008;40(10):1235-1239. PMID: 18806795.
3. Awano T et al. Genome-wide association analysis reveals a SOD1 mutation in canine degenerative myelopathy that resembles amyotrophic lateral sclerosis. Proc Natl Acad Sci U S A. 2009;106(8):2794-2799. PMID: 19188595.
4. Coates JR et al. Canine degenerative myelopathy. Vet Clin North Am Small Anim Pract. 2010;40(5):929-950. PMID: 20732599.
5. OMIA:001298-9615 (prcd), OMIA:001466-9615 (EIC), OMIA:000263-9615 (DM).