Juvenile Myoclonic Epilepsy Type (JME) in Rhodesian Ridgebacks

Juvenile myoclonic Epilepsy is an inherited health issue that sadly affects the Rhodesian Ridgeback. The condition can be likened to the human equivalent of JME, sharing the same symptoms as well as the same age at which the disorder affects dogs as it does humans. As such, a lot of research into the condition has been carried out with an end goal having been to establish the cause of the damaging gene mutation that causes JME in Rhodesian Ridgebacks.

Symptoms associated with JME

The condition typically starts to show when a Rhodesian Ridgeback is about 6 weeks to 6 -months old when puppies start to show sudden, involuntary muscle spasms which are referred to as myoclonic jerks. Often puppies with the condition look as if they are receiving electric shocks when they first start having spasms which can be extremely distressing from both dog and owner.

The seizures are often triggered by flashes of light with around 35% of Rhodesian Ridgebacks with the condition suffering from a photosensitivity of one sort or another. Puppies and young dogs can experience an episode when they are relaxed, sleepy, napping or when they are just falling asleep. However, they can start twitching when they are walking, standing still or sitting down too. With this said, there is typically no changes in a dog's behaviour when they are having an “episode”.

These sudden, involuntary jerks tend to occur on a dog's body, their shoulders and lower necks which as a result sees an affected dog nodding their heads and muscles around the face twitch too. The jerks can be slight or severe depending on how affected a dog happens to be by the condition. Once a seizure is over, dogs often seem to be afraid and confused. It is also worth noting that Ridgebacks suffering from the condition do not sleep well because of the seizures which can occur as many as 150 times in any 24-hour period. As such, it is often much kinder to put a dog with JME to sleep rather than letting them suffer unnecessarily.

The genetics involved

JME in Ridgebacks is caused by a gene mutation which as a result sees dogs lose control of the muscles in certain parts of their bodies. In short, the signal to "stop" muscle contractions is lost when a dog inherits the disorder. The actual gene mutation is unique to the Rhodesian Ridgebacks although other dogs can also suffer from JME but through another type of gene mutation. The gene responsible in Ridgebacks the DIRAS1 gene. Research has also shown that the carrier rate in the breed stands at 15%.

Mode of transmission

The disorder is an autosomal recessive one which means that both parent dogs would have to carry the mutated allele for their offspring in inherit JME. With this said, a "carrier" would not show any symptoms of suffering from the disorder but when 2 carriers are mated, the chances of puppies inheriting the condition stands at 25% with 50% of them being what is referred to as "asymptomatic carriers" and 25% of puppies neither being affected or carriers.

Prognosis

Research carried out in Finland in collaboration with the Rhodesian Ridgeback Club of Finland has established that the "mutation" has existed in the breed for a long time. Sadly, the prognosis for puppies or older Ridgebacks suffering from JME is never promising although affected dogs can be treated using anti-convulsive medication and this includes one that is typically used to treat children suffering from the disorder which is called Levetiracetam. However, the drug has not proven effective when used long-term in dogs and this includes in Rhodesian Ridgebacks.

Testing for juvenile myoclonic epilepsy

As previously mentioned, studies into the disorder carried out in Finland have now identified the recessive gene responsible for dogs inheriting the disorder and that Ridgebacks in the UK and Europe are more at risk of suffering from JME although no dogs from the US were included in the research. With this said, responsible Ridgeback breeders must have stud dogs tested through Laboklin to establish whether they have 0, 1 or 2 copies of the gene mutation. It is worth noting that this test would not establish if a Ridgeback suffers from any other form of epilepsy.

The test allows breeders to make an informed decision when it comes to breeding programmes allowing them to safely breed a "carrier" to a Ridgeback that has tested "clear" of juvenile Myoclonic Epilepsy. This is turn would allow for a larger gene pool to be drawn from, bearing in mind that "carriers" would not have the disorder and would only pass it on to their offspring if they are bred to another "carrier" or an "affected" Ridgeback.

Note for prospective Rhodesian Ridgeback owners

Anyone wishing to share a home with a Ridgeback, should always ask breeders if their stud dogs have been tested for juvenile myoclonic epilepsy and to see whether they have tested clear, whether they are carriers or affected. Responsible Ridgeback breeders would be only too happy to show potential buyers that the relevant tests have been carried out and that their puppies have been bred responsibly.