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| Some of the medications used to control seizures. These may control symptoms in dogs with early stage Lafora disease, but there is currently no cure. |
When we think about
animal-based research to benefit humans, we tend to think about animals in
laboratories. But clinical-based research can incredibly helpful, and may
benefit both species.
For example,
collaboration between pet owners, vets and researchers at the University ofSurrey’s School of Veterinary Medicine and Fitzpatrick Referrals in Surrey is
helping dogs and children with a rare, severe form of epilepsy.
The condition, Lafora disease, is very rare in dogs
– although more prevalent in miniature wirehaired dachshunds, and has been seen
in beagles and Basset hounds. Potentially, the genetic mutation that causes the
disease could occur in any breed of dog spontaneously but
it is autosomal recessive, so they need two copies of the disease gene to have
disease i.e. both parents must be carriers or affected. The disease occurs due
to a mutation in the Epm2b gene which
leads to accumulation of glycogen in cells (Lafora bodies).
The disease affects around 50 children worldwide. Laforadisease is a fatal form of epilepsy caused by a genetic mutation, leading to
abnormal levels of glycogen in the body. These abnormal levels of glycogen
cause children and dogs to suffer progressive seizures, dementia and loss of mobility.
In dogs, anti-epileptic drugs control seizures in the early stages of the
disease, but there is no curative or long-term treatment available currently.
Understanding the signs and progression of the
disease may help develop an effective treatment which could be used to treat
affected children and dogs.
Veterinary researchers surveyed the owners of 27
miniature wirehaired dachshunds over the course of 12 months to study the
clinical signs and physical advancement of the disease. The good news is that this involved patients with naturally occurring disease.
They discovered that the average age of onset of
clinical signs in dogs was around 7 years. The most common clinical sign of
Lafora are reflex and spontaneous muscle contractions, uncontrollable jerks and
generalised seizures. Other common signs include focal seizures, jaw
smacking, fly (of the non-existent kind) catching, panic attacks and aggression. Reflex and
spontaneous muscle contractions was a clinical sign in 77.8 per cent of
affected dogs. 51.9 per cent of affected dogs experienced uncontrollable jerks
and 40.7 per cent experienced generalised (sometimes referred to as grand mal) seizures.
Signs that developed later in the
disease include dementia (51.9%), blindness (48.1%), aggression to people
(25.9%), aggression to dogs (33.3%), deafness (29.6%) and faecal (29.6%) and
urinary (37.0%) incontinence as a result of loss of house training
(disinhibited type behaviour). Read more here.
It sounds simple, but characterising rare diseases
like this is incredibly challenging yet vitally important. How does a
veterinarian know that a dog or puppy has Lafora disease, and not another
seizure disorder?
For veterinarians, differentiating Lafora from
other seizure disorders can be difficult, but is done on the basis of a) the
presence of characteristic myoclonic (jerking) type seizure in response to flashing
lights, sounds, movement; b) genetic testing and c) MRI changes (cortical
atrophy), although these changes are not specific to Lafora.
Genetic testing is performed on blood submitted to the
University of Toronto or via the Dachshund Breed health Council testing scheme.
Dr Clare Rusbridge, Reader in Veterinary Neurology
at the University of Surrey and Chief Neurologist at Fitzpatrick Referrals,
said: “Lafora disease is a fatal disease that causes unbearable suffering for
dogs and in rare cases young children.”
“Due to its rarity, little is known about the onset
of this illness but what we have discovered, with the help of dog owners, is
the clinical sign of Lafora helping to lead to quicker diagnosis. The more we
learn about Lafora, the better chance we have of treating it effectively.”
The longstanding relationship between Dr Rusbridge
and the Hospital for Sick Children in Toronto has led to the ground-breaking
collaboration between human and veterinary medicine, which led to the discovery
of the canine Lafora genetic mutation in 2005.
This research has already helped reduce the
incidence of Lafora in dogs and thereby reduced suffering. Campaigning by the
Wirehaired Dachshund Club and Dachshund Breed Council has led to an increased
awareness and testing for the disease in breeding dogs. In 5 years, the proportion
of litters bred with a risk of Lafora-affected puppies has been reduced from
55% to under 5%.
This represents huge progress, but there’s still a
need to develop an effective treatment. Its another important example of how study of naturally occurring, rather than experimentally induced disease, can benefit humans and animals.
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