Feline Cutaneous Asthenia in Cats
Feline cutaneous asthenia (FCA), also known as Ehlers-Danlos syndrome, is a disease characterized by deficient levels of collagen, the protein molecule necessary for providing strength and elasticity to the skin and ligaments, along with much of the rest of the body. The condition is part of a group of hereditary disorders characterized by skin that is unusually stretchy and droopy. It is caused by a genetic mutation that is passed from parent to offspring, and while more than one genetic disorder is suspected, this condition cannot be determined by skin and tissue samples, it is diagnosed through observation.
Collagen is the “glue” that holds the body together, and a lack of collagen will result in abnormal collagen synthesis and fiber formation. Animals affected with this disorder suffer from painful dislocation at the joints due to the instability of the ligament fibers that hold the bones to each other. The ligaments normally stretch with movement, but without the elasticity needed to return to their original form they stay stretched out, allowing the bones to pop out of their connective joints. This creates a painful physical environment for the sufferer of cutaneous asthenia. The lack of collagen also affects the structure of the skin. Without elasticity, the skin does not return to the body when it has been stretched away from the body, eventually drooping heavily. This slack also weakens the skin's resilience, making the skin easy to injure and prone to tearing, bruising and scarring. This disease is rare, and has been clearly identified in only a small number of cats. Animals are usually diagnosed at a young age.
Symptoms and Types
Symptoms of cutaneous asthenia generally include saggy skin, with redundant folds of skin. The skin is soft, delicate, and thin, with insufficient elasticity. The skin is easily torn, often leaving wide “fish mouth” type wounds that bleed very little, but that leave scars which widen over time. There may also be scars on the skin that are unaccounted for. Your cat may have swelling under the skin of the elbows, due to the bones putting pressure on the skin when the cat is at rest, and bruising and bleeding under the skin (hematoma) of the elbows, and throughout the body. Lacerations on the back and head are also common. Collagen is low internally as well as externally, making it possible for internal structures to rupture, with resultant internal bleeding.
For cats, symptoms will often show at about eight weeks of age. Normal play with litter mates will leave large tears in the skin, which heal quickly but leave lasting scars. Hernias have also been reported in cats affected with cutaneous asthenia.
This condition tends to affect the following breeds:
- Domestic shorthairs
- Domestic longhairs
The primary cause of this medical condition is genetically based. It is caused by a genetic mutation that is passed from parent to offspring, and can be either dominant – from both parents, or recessive – from only one parent. In the dominant form, both parents are carriers of the mutated gene, with neither animal showing symptoms. With the recessive form, one parent may be a carrier, with no symptoms present. In either case, it is generally advised that the parents of an effected animal not be used for further breeding, and that the siblings of the affected animal also be prevented from breeding.
An examination of the skin's extensibility is performed by stretching the skin to its full ability, observing any lack of discomfort in the animal, and measuring the extent the skin stretches to. The resulting measurements are based on the Skin Extensibility Index (SEI), which measures the skin that has been stretched (using the dorsal skin on the back), divided by the length of the animal from the back crest of the skull to the base of the tail. The numerical value that is found determines the severity of the condition. The expected numbers are an index of higher than 19 percent for cats.