AUTOSOMAL RECESSIVE INHERITANCE
This article will be helpful in understanding how CA is inherited. Breeders especially are urged to study it carefully.
Autosomal = a pair of like chromosomes.
Recessive = two copies of a gene must be present before a dog is affected by the disease or trait, thus a carrier would have one copy of the gene to pass on to offspring but would not actually have the disease or trait.
Important points covered:
1. Simple autosomal recessive genetic conditions are inherited only from parents that are carriers for the recessive gene or are themselves affected by the condition.
2. Both affected and carrier parents can pass the recessive gene on to their offspring.
3. Both parents of an affected animal must be carriers of the recessive gene.
4. Breeding carriers will not always produce an affected offspring.
5. Clear bred to Clear will only produce Clear offspring
CA – DR. BELL & OESCA
These articles are helpful to get an overview of the problems we face, how we began, and how far we have come in working together.
Some of the important points:
1. CA is not a single kennel problem
2. CA is an autosomal recessive gene
3. The closest common ancestor in pedigrees is not necessarily a carrier
4. To keep our gene pool diverse, we should not discard dogs from breeding programs simply because they are related to a dog affected with CA.
CEREBELLAR ABIOTROPHY (CA) SYMPTOMS
This short article gives a description of the typical gait of a dog affected with CA.
CEREBELLAR ABIOTROPHY IN THE OLD ENGLISH SHEEPDOG: Its Cause And Diagnosis
This article is a great resource for understanding CA in our breed. A must read before you view the CA registry.
Important points covered are:
1. CA is caused by a degeneration of cells in the cerebellum of the brain.
2. CA causes uncoordinated movements of the limbs.
3. CA is not painful and need not shorten a dog's life.
4. CA can be diagnosed through clinical observation, examination of the cerebellum after death, and an MRI in advanced cases.
*Editor's note: As of October 2012 the CD(CA) Genetic Test will diagnose CA before symptoms may appear.
5. CA is caused by an autosomal recessive gene, which means both parents must carry the gene to produce an affected dog.
1. Initial contacts
If you are planning to euthanize your dog, please contact Dr. Olby by email firstname.lastname@example.org or by telephone 919-513-8286 or 919-513-6692 (clinic) as soon as possible as she will be able to talk directly to your veterinarian about these protocols. If there is a College of Veterinary Medicine close by, she will be able to contact someone there and see if the full protocol can be carried out. Although it is difficult, the more time you can give Dr. Olby, the better she will be able to organize additional support. If Dr. Olby is not available (the receptionist in the neurology clinic will know when she is out of town), please call or email her assistant Kim Williams at 919-513-7235 email: Kimberly_Williams@ncsu.edu.
2. Blood sample and pedigree
We need 6-10mls of blood taken into an EDTA tube (or tubes). If you have already sent blood, this is not a priority although we like to take duplicate samples if possible. If we do not have your dog's pedigree we would like a copy of that as well.
3. Tissue to establish a diagnosis
We need your veterinarian to remove your dog's brain after euthanasia causing as little damage as possible and place it in a container of 10% formalin with enough formalin in it to entirely cover the brain. The container should then be tightly sealed and placed in at least two layers of plastic bags, then placed in a Styrofoam, or well-padded cardboard box with the blood samples and sent to us overnight using a shipping service that allows the package to be traced such as Fed Ex. Many veterinarians are not comfortable with, and do not have the equipment necessary for removal of a dog's brain, in which case we ask that they decapitate the dog and send the head to us packed in ice as soon as possible.
4. Tissue for RNA extraction
In order for this tissue to be obtained, the veterinarian must have access to liquid nitrogen and be able to remove the brain in a sterile fashion immediately after death. Once the brain has been removed, a portion of one of the cerebellar hemispheres should be removed, placed in aluminum foil or a cryotube and frozen in liquid nitrogen. We need a 1cm square block of tissue. This frozen tissue has to be shipped on dry ice to prevent thawing. The remainder of the brain (and cerebellum) should be placed in 10% formalin and shipped to us as listed above: it has to be shipped separately to the frozen sample to avoid freezing of formalin fixed tissue.
Please avoid shipping on a Friday as this would mean the samples would sit in the mail over the weekend. The blood samples will be fine if simply kept in a 4 degree centigrade refrigerator until is shipped on Monday, and formalin fixed tissue is stable at room temperature. Please notify us on the day the sample is shipped if possible by phone: 919-513-7235 or by email: Kimberly_Williams@ncsu.edu.