Final answer:
Ehlers-Danlos syndrome (EDS) causes skin fragility in dogs due to a deficiency in type-III collagen, leading to extremely stretchy skin that easily bruises and is slow to heal.
Step-by-step explanation:
Ehlers-Danlos syndrome (EDS) is a group of genetic disorders affecting the collagen in the extracellular matrix (ECM), which provides structural support to tissues. In the case of EDS, there is a deficiency in the type-III collagen due to either a deficiency of the enzyme hydroxylase or mutations in the amino acid sequences during collagen synthesis. This causes a progressive deterioration of collagen, which is paramount in maintaining the strength and elasticity of the skin. As a result, one of the most prominent characteristics of skin fragility in dogs with Ehlers-Danlos syndrome includes extremely stretchy skin that is easily bruised and slow to heal when injured. With EDS affecting different sites in the body, skin and vascular problems are the major symptoms expressed.