Health and Genetics of Border Collies -
A Breeder and Buyer's Guide 2002

The Border Collie stands alone in its exceptional ability to work livestock. ABCA defines the breed by this working ability.  The main goal of any Border Collie breeder should be to produce sound, useful, working dogs. While Border Collies also excel in many non-herding activities, they should be bred primarily to work livestock. The ultimate responsibility for maintaining the integrity of this as yet unspoiled breed lies with the breeders. Breeders are urged to take this responsibility seriously. Puppy buyers are encouraged to buy only from those breeders who do take this responsibility seriously.

 

Both breeders and buyers should understand there are risks involved in any breeding, regardless of the amount of care taken to avoid problems. In order to ensure a healthy gene pool for future generations of Border Collies, breeding prospects should be evaluated with reasonable concern for potential problems and realistic goals for what will be produced. The breeding prospect should be considered as a whole being, with positive and negative aspects of the individual being weighed and balanced for an overall picture of a dog's suitability. Breeding should be undertaken with thoughts of what the parents have to offer to their pups that could benefit the breed.

 

Genetic Diseases

 

To be considered a genetic disease, a health problem needs to have been demonstrated to be heritable, that is, passed on through one or both parents. Some diseases have high heritability, which means if the genes are present, the individual will have the disease, and some diseases have low heritability, meaning both genetic and environmental factors are involved in whether the disease occurs. It is generally easier to control diseases with high heritability because all individuals with the genetic makeup for the disease can usually be identified. The term heritable disease should be distinguished from the term congenital disease, or problems that are present from birth, which may or may not be heritable.

 

Border Collies are considered to be a generally healthy breed. However, as in all animals, there are some potential health problems. This information is presented to help both breeders and buyers to become more aware of some of the health and genetic issues in the breed at this time.

 

The primary genetic diseases currently thought to be a problem in the breed are as follows:

 

Hip Dysplasia (HD) HD is by far the most prevalent known genetic disease that affects Border Collies. Factors that contribute to the development of HD ultimately cause the hip joint to be damaged. Joint damage called osteoarthritis, also known as degenerative joint disease (DJD) is manifested by cartilage and bone breakdown and irregular bony remodeling in response to stresses and inflammatory processes in the joint. DJD is, in effect, the identifiable result of factors that cause HD. The standard for diagnosing HD at this time is still the front extended-leg view of the hips on x-ray such as that evaluated by The Orthopedic Foundation for Animals (OFA). OFA reports a 12.6% affected rate for Border Collies evaluated from 1974-2000. This HD incidence ranks them somewhere in the middle of the dog breeds. Pre-submission screening and selection for probable favorable OFA results by owners and their veterinarians very likely skews this percentage significantly to the low side. Therefore, the true incidence of HD is probably much higher, possibly as high as double the OFA figure. If true, this would mean, on average, one out of every four Border Collies has HD. 

 

Despite what some may claim, data from numerous scientific studies provide overwhelming evidence that HD is an inherited disease. It is thought to be caused by at least three and possibly as many as six primary genes. The number of genes involved, combined with the high incidence, means it's probable that most Border Collies are at least carriers of one or more of the genes that can contribute to the development of HD, even if they don't have the disease themselves. To confuse matters more, the expression of the disease is affected by environmental conditions such as the type and amount of food a dog gets at critical growth stages, as well as the type and amount of exercise and activity it gets. It must be remembered, however, that these environmental factors do not cause HD. They merely affect whether the HD genes present in that individual will be expressed to the fullest. Even if the expression of HD in a certain individual is suppressed by careful control of environmental factors, you have not changed the dog's genetic makeup. That dog will still pass on the genetic tendency for HD just as if it actually had the disease. Conversely, if a dog does not have the genes for HD, it won't develop the disease no matter how it's raised.

 

The possible incidence of one in four dogs may seem falsely high if the presence of HD is defined by dogs showing significant lameness.  The clinical symptoms of HD do not always correlate well with the severity of the disease as judged by radiological findings. Border Collies with HD that are fortunate enough to show few if any symptoms may have progeny that are not so fortunate.  The exact complex combination of genetic and environmental factors that contributed to an individual's lack of symptoms will not occur in its pups.  Therefore, it is important to remember that a high tolerance of an individual for the effects of HD does not mean that individual is suitable as a breeding prospect.

 

The best way, at this time, to avoid producing puppies with a predisposition to develop HD is to test both parents and be aware of the hip status of other related dogs such as the parents' other progeny, the parents' parents, and the littermates and half siblings of the parents. The more tested, unaffected dogs there are in the pedigrees, the better the chances of producing unaffected pups. Unfortunately, even following the most stringent guidelines, puppies may still be produced that will develop HD. This does not mean there's no point in testing parents before breeding them. This line of false reasoning is akin to arguing that, because working parents will occasionally produce pups that won't work, there's no point in testing the working ability of breeding stock. Selection for good hips will increase your chances of producing pups with good hips, but it's unrealistic to expect that puppies with HD will never be produced from tested, unaffected parents. Likewise, it is unrealistic to expect every dog who has ever produced a pup with HD to be banned from breeding. Since it's likely that most non HD-affected Border Collies are carriers of one or more of the genes for HD, most dogs will produce at least one pup with HD if bred enough times. Sooner or later, a cross with another carrier will produce the wrong combination of the HD genes and an affected pup will result.

 

Given the incidence and complexities involved with HD in our breed, the recommendations at this time are to breed only hip tested, unaffected parents. Also, try to plan crosses having as many tested, unaffected dogs in the pedigrees of both parents as possible. If an affected puppy is produced from a cross of two unaffected parents, at the very least, don't repeat that particular cross because that affected puppy has proven that the two parents can together provide the right combinations of genes to create more puppies with HD.

 

The ABCA Health and Genetics Committee is investigating a promising new technique that measures several factors involved in the development of HD. This procedure involves taking hip x-rays on a sedated dog while the dog is in a kneeling position. This angle is favorable for identifying strengths and weaknesses in the hip joint in a more natural, weight-bearing position. This type of measurement is called a Dorsolateral Subluxation (DLS) measurement. ABCA is planning a study to evaluate this technique in 8-12 month old Border Collies.

 

DLS diagram

Diagram of the position for x-ray in the DLS procedure 

 

 

Collie Eye Anomaly (CEA) CEA is a congenital disorder where the parts of the eye, particularly the retinal area, do not develop normally. 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.

 

This disease is much more straightforward than hip dysplasia in both its inheritance patterns and in our ability to control it. CEA is an autosomal recessive disorder. Autosomal means it is passed on and expressed equally in males or females. Recessive means a dog may carry a "bad" (mutated) CEA gene and pass it on to its offspring without having the disease itself. A dog is defined as Clear (or Normal) if it has no "bad" CEA genes. A dog is defined as a Carrier if it has one "bad" CEA gene and one normal gene. The eyes of both the Carrier and the Clear dogs will be unaffected by the disease. A dog which has two "bad" CEA genes is defined as Affected. The outcomes of the different crosses of these dogs are as follows:

Clear X Clear = 100% CEA Clear puppies

Clear X Carrier = on average, 50% Clear, 50% Carriers

Clear X Affected = 100% Carriers

Carrier X Carrier = on average, 25% Clear, 50% Carriers, 25% Affected

Carrier X Affected = on average, 50% Affected, 50% Carriers

Affected X Affected = 100% Affected

 

The incidence of CEA in Border Collies in North America is about 2.5%. The carrier rate is probably ten times that figure, or 25%.

 

It is possible to determine whether a dog is Affected with CEA by having it examined by a Diplomate of the American College of Veterinary Ophthalmologists (DACVO).  To be sure of obtaining accurate results, however, puppies should be examined before they are 12 weeks of age, because some dogs have a mild form of the disease called "go normal," where normal tissue grows over and covers up the diseased area of the eye as the dog matures.  These "go normal" dogs cannot reliably be identified by an eye exam in adulthood, but they will pass on a "bad" CEA gene to their offspring just as if they had full blown expression of the disease.

 

Until a few years ago, the only way to know if a dog was a Carrier was for it to produce an Affected puppy.  Since there are so many unknown Carriers, that meant there was no way to prevent inadvertently producing Affected pups.  Since 2005, however, there has been a reliable DNA test for the CEA gene, which can determine whether a dog is Affected, a Carrier, or Clear.  The test is being administered through OptiGen, LLC, and further details about it can be obtained on their web site at www.optigen.com.

 

It is recommended that breeders utilize the OptiGen test to determine the status of all dogs used for breeding.  A Clear (Normal) dog bred to a Clear (Normal) dog will produce only Clear puppies, so the offspring of such a mating need not be DNA tested; their status is known.  An Affected dog should be bred only to a Clear dog, and only when the dog's exceptional merits are such as to justify a breeding that will produce pups which will all be Carriers.  Carriers, too, should be bred only to Clear dogs, in order to avoid producing affected pups; at the same time, breeders should not exclude Carriers from their breeding program, as this would be detrimental to the goal of maintaining the highest level of working ability in our breed and would also tend to constrict the gene pool.  All pups with a Carrier parent should be tested to determine their CEA status before being bred.  If testing all breeding stock is not feasible, at a minimum breeders should ensure that one parent of any litter is DNA Clear, as this is the only way to be sure that Affected pups will not be produced.  Breeders and owners should be frank and forthcoming in informing anyone inquiring about a breeding or a puppy purchase about the CEA status of the dogs involved, and the significance of that for any offspring they may have.

 

Epilepsy Epilepsy is a disease characterized by seizures or "fits" as they are sometimes called. Although it's clear Border Collies can be affected with epilepsy, the incidence and heritability in our breed are unknown. The ABCA is supporting research aimed at finding the gene(s) that may cause epilepsy in the breed.

 

Since there can be many causes, determining why a dog has seizures is a complex process. The diagnosis of primary epilepsy is made based on negative results for other causes of seizures. Therefore, it is a diagnosis made by exclusion rather than by a specific test. Since we have little breed-specific information to go on, ABCA breeding recommendations concerning this disease are based on those for other affected breeds in which the disease is more well-defined. Recommendations are: Do not breed affected dogs. If two unaffected dogs produce an affected puppy, do not repeat that cross.

 

Genetic diseases not considered to be a significant problem in the breed at this time:

 

Progressive Retinal Atrophy (PRA) PRA is a progressive disease where tissue in the retina of the eye is destroyed. It may initially be noticed as decreased ability of the dog to see at night, and may eventually progress to total blindness.

 

Despite the persisting impression that this genetic disease is prevalent in the breed, extensive investigation has shown the incidence of PRA in Border Collies in North America to be extremely low to non existent. Therefore, the ABCA does not currently consider it a major health concern.

 

Elbow dysplasia Elbow dysplasia is a general term used for what is essentially three different types of degenerative elbow disease. These diseases may occur singly or together and are thought to be caused by several different genes.

 

More and more owners are having their Border Collies' elbows evaluated each year. However, OFA reports a 0% incidence of elbow dysplasia for 210 Border Collies tested from January 1974-December 1999. ABCA does not consider elbow dysplasia a significant health problem in the breed at this time.

 

Common diseases with questionable heritable cause:

 

Osteochondritis Dissecans (OCD) OCD is a condition that occurs primarily in puppies between the ages of 4-9 months, but can also be found in older puppies. It is considered to be a common disease in rapidly growing dogs of large breeds. However, medium breeds such as the Border Collie can also have a high incidence of this disease. It is seen twice as often in males as in females. The shoulder joint is the most commonly affected site but it can be seen in stifles, elbows, hocks or other joints. The diagnosis is usually confirmed by x-ray of the involved joints.  In approximately one third of the cases of OCD, the disease is bilateral (in both joints). Occasionally, it is present in several different joints in the same individual. OCD is thought to be caused by a problem in the growth rate of the joint cartilage relative to the underlying subchondral bone.

 

Although the factors that cause OCD are not completely understood, direct factors considered to be involved in the development of OCD are rapid growth and trauma to the joint. Indirect factors affecting rapid growth include nutrition, hormones, and genetic predisposition to rapid growth and large size. Indirect influences that may lead to increased trauma to the joint include conformation and behavior, which are also influenced by heredity. Therefore, the genetic link for most types of OCD is considered to be indirect, that is, an inherited tendency. Certain sites for OCD lesions, such as the elbow, appear to have a greater direct genetic contribution and a higher heritability than other sites, such as the shoulder. The most important contributing factor in OCD of the shoulder, the most common site, is thought to be trauma. OCD can best be prevented in growing puppies by controlling the main precipitating factors, overnutrition and activities that could result in injury to the joints.

 

Because factors involved in the heritability of OCD are considered to be indirect, and therefore not easily controlled by selection, ABCA has no breeding recommendations for OCD at this time.

 

Common diseases with no known heritable contribution:

 

Focal/Multifocal Acquired Retinopathy (FMAR): This inflammatory eye disease is common in many working breeds and is probably the most frequently seen retinal lesion in Border Collies. Sometimes called "distemper scars" or "worm scars", it is characterized by lesions in the retina that can accumulate over the years, often leading to impaired vision and sometimes leading to blindness.  The lesions have a typical "bull's eye" pattern, and tend to be asymmetrical (affect one eye more than the other).  The age of onset and rate of progression varies greatly from individual to individual.  Males are more frequently affected than females.  The characteristics of this disease strongly suggest environmental cause; no heritable pattern has ever been established for its occurrence.  Its pathology clearly distinguishes it from  PRA, although it is sometimes mistaken for PRA, especially in the later stages of the disease.

 

In summary, this brochure is meant to provide a brief description of some common diseases, some current knowledge about their heritability in our breed, and relevant breeding recommendations. Please remember, diseases present in Border Collies are not limited to those discussed here.  Also remember, these recommendations are guidelines, not restrictions.  Keep track of updated and more in depth Border Collie health and genetics information by checking the ABCA web site at www.americanbordercollie.org .

 

For more information contact:
American Border Collie Association, Inc.
P.O. Box 100 · Cataula, GA 31804
Phone: 706-322-4400 · Fax: 706-322-4004
Email:

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