Congenital Myasthenic Syndrome (CMS) in Cats

Congenital myasthenic syndrome or CMS is a condition that affects both the Devon Rex and the Sphynx. The disorder affects a cat's muscles causing weakness in them. Cats suffering from the condition often bob their heads because they find it hard to hold them steady simply because their muscles are so weak. The first signs of there being a problem usually become evident when kittens are anything from three to twenty-three weeks old and their condition can remain the same or it could get gradually worse as time passes. CMS is an autosomonal recessive, genetic disorder and any affected cat should not be used in a breeding programme.

Signs to Watch Out For

As previously mentioned, kittens start to show signs of there being a problem when they are around 3 to 23 weeks old. The signs are particularly obvious just after kittens have been playing, been stressed out or excited about something which is when they show the most weakness in their muscles. The signs to watch out for include the following:

• A high stepping gait
• Head bobbing
• Shoulder blades protrude more than they should
• Easily tired
• Short stride
• Tremor
• Collapse
• Cats with the condition often rest their front legs on something adopting a very chipmunk-like position

It's worth noting that cats with the one copy of the mutated gene are carriers and although they may not be affected by the condition, they could pass CMS on to their offspring. As such any cat known to suffer from the condition should never be used in a breeding programme, but spayed or neutered when the time is right for them to undergo the procedures.

Breeds Most at Risk

The breeds known to be most at risk of inheriting CMS include the following:

• Devon Rex
• Sphynx

Both female and male cats can be affected by the disorder although in some cases, the symptoms do not get any worse whereas in other cats, they get that much worse. However, cats with the disorder often die when they are around 2 years old either because they choke on their food or because they experience aspiration pneumonia due to muscle weakness.

Testing for Congenital Myasthenice Syndrome

There is now a test available for Congenital myasthenic syndrome and all breeders should have their stud cats tested for the condition. The test would show the following results:

• Normal Congenital myasthenic syndrome (CMS) genetic test result: this establishes that a cat does not carry the gene mutation that causes the disorder
• Carrier Congenital myasthenic syndrome (CMS) genetic test result; this establishes that a cat has the one copy of the mutated gene and as such they are carriers although they would not develop any symptoms, they could pass the disorder on to their offspring
• Affected Congenital myasthenic syndrome (CMS) genetic test result: this establishes that a cat has two copies of the gene mutation and as such they would suffer from Congenital myasthenic syndrome and would pass it on to their offspring. As such, cats should be spayed or neutered when the time is right to prevent them being used in a breeding programme