Genetic Diseases in Border Collies
The study of genetics is fascinating. It is quite predictable, and a field I enjoyed studying at university and teaching to students.
Genetic Diseases are those that can be passed on from parents to offspring. They are inherited from either one or both parents. Highly heritable diseases are present if the genes are present in both parents. Lowly heritable diseases may only be present if both the gene and environmental factors are involved.
While Border Collies are a robust breed, there are some genetic diseases that can be present. All of the possible Border Collie genetic diseases are recessive or complex. Being recessive means that both parents must possess the gene for the disease to present. Being complex means factors other than genes (eg. environment) influence the expression of the disease. A dog that possesses the recessive gene for a disease is called a carrier. This means they don't show signs of the disease themselves, but can pass it on to their offspring.
While having a dog that is a carrier of a genetic disease is not a problem, it is important for breeders to know what their dogs may be carriers of. The procedure for definitely knowing whether a dog is a carrier of a disease is simple. It involves rubbing a small brush inside the cheek of the dog and sending the sample off to a laboratory for testing. The sample can be tested for one or more diseases or even for other genetic factors such as colouring and breed specific markers. If a breeder does not know the genetics of their dogs, it is possible to breed two carriers of a disease and produce puppies that suffer from the disease. When breeders refer to puppies being clear of genetic diseases due to parentage it usually means the puppy's grandparents have been genetically tested and found to be clear, meaning the puppy's parents cannot have the diseases. Hence, the puppies have to be clear of the diseases too.
So, if you choose a responsible breeder and ask the right questions you should have no concerns about the recessive diseases of Border Collies.
There three well known genetic diseases that can be tested for are: Collie Eye Anomaly (CEA), Neuronal Ceroid Lipofuscinosis (CL) and Trapped Neutrophil Syndrome (TNS).
Collie Eye Anomaly (CEA):
CEA refers to an inherited abnormality in the development of the retina, optic nerve and choroid of the eye. The severity of the disease ranges from no visual impairment to blindness. It is not a progressive disease and affected dogs usually have only mildly impaired vision.
It is known to affect Collies, Border Collies, Australian Shepherds and Shetland Sheepdogs.
Neuronal Ceroid Lipofuscinosis (CL):
Affected dogs lack a certain enzyme important for cellular metabolism. This leads to an abnormal accumulation of cellular waste product in cells (particularly those of the nervous system) causing disruption of normal cellular function. Affected dogs appear normal until around fifteen to twenty months of age. The following neurological symptoms may then appear:
* behavioural changes,
* aggression and irrational fears,
* abnormal gait,
* seizures, and
* difficulty with balance.
Affected dogs progressively deteriorate and most die or are euthanised by three years of age.
Trapped Neutrophil Syndrome (TNS):
TNS is a disease in which white blood cells (neutrophils) are produced but are not able to move from the bone marrow into the blood stream. Affected dogs have a compromised immune system and are not able to fight off infection. Pups are very prone to infections and often die or are euthanized within their first few months.