Inherited mechanobullous disease caused by a defect in type VII collagen (anchoring fibrils of the dermoepidermal junction), which produces skin and mucosal blisters after minimal trauma. In the Central Asian Shepherd Dog it is associated with a mutation in the COL7A1 gene, with autosomal recessive inheritance, analogous to human dystrophic epidermolysis bullosa.

Affected breed: Central Asian Shepherd Dog. In the population studied by Niskanen et al. (2017) the carrier frequency was approximately 28%; the spread of genetic testing has reduced the incidence. Limited data on current frequencies in Spain.

- Skin blisters and erosions after minimal trauma or friction
- Mucosal involvement: oral, oesophageal and sometimes ocular
- Nail dystrophy and loss
- Scars and milia in healing areas
- Secondary skin infections
- Neonatal onset or within the first days of life

Dystrophic epidermolysis bullosa has been described in the Central Asian Shepherd Dog (Alabai) in puppies with skin and mucosal blisters from birth. Niskanen et al. (2017) identified the causal variant in the COL7A1 gene, which encodes the alpha chain of type VII collagen, a component of the anchoring fibrils: a nonsense mutation c.4579C>T p.(Arg1527*), with autosomal recessive inheritance, analogous to human dystrophic epidermolysis bullosa. Other breeds affected by different COL7A1 variants are the Golden Retriever (p.G1906S) and the Basset Hound (complex rearrangement with frameshift).

- Test breeding animals with the COL7A1 test before mating
- Do not mate two carriers: 25% risk of affected homozygotes
- A carrier may be mated to a clear animal; offspring intended for breeding must be tested
- Exclude affected animals from breeding
- Avoid spreading the allele to lines where it is not present

Differential diagnosis with other epidermolyses (simplex, junctional), pemphigus and dermatophytosis. Biopsy with direct immunofluorescence and type VII collagen immunomapping is suggestive, but confirmation is genetic. Supportive management: avoid trauma, soft feeding, treatment of infections and monitoring of oesophageal/oral lesions.

1. Niskanen J et al. (2017) Nonsense variant in COL7A1 causes recessive dystrophic epidermolysis bullosa in Central Asian Shepherd dogs. PLoS One 12(5):e0177527. PMID: 28493971
2. Garcia TM et al. (2020) A COL7A1 variant in a litter of neonatal Basset hounds with dystrophic epidermolysis bullosa. Genes (Basel). PMID: 33291836
3. OMIA:000341-9615. Epidermolysis bullosa, dystrophic in Canis lupus familiaris. https://omia.org/OMIA000341/9615/