Health & Genetics of the Scotch Collie
Multiple Drug Resistance 1 (MDR1)
Problem: MDR1 is a disease that prevents a dog from detoxing harmful substances. A very tiny part in the dog's body, the p-glycoprotein, has a pump that normally removes toxins from the dog's cells, keeping him safe and healthy. With MDR1, this pump is either compromised (n/M) or broken altogether (M/M).
Solution: We test every Rosewyn dog and and plan our breedings with the goal of puppies being either Clear (n/n) or Carrier (n/M). Before they go home, we test the DNA of each puppy in the litter.
Rationale: MDR1 is an autosomal incomplete dominant disease, which means that a dog only needs to inherit one copy of the mutation to be be affected by it. Think of MDR1 Carriers as "MDR1 Lite".
|n/n||0 copies of mutation inherited||Clear|
|n/M||1 copy of mutation inherited||Carrier (somewhat affected)|
|M/M||2 copies of mutation inherited||Affected|
MDR1 reactions are life-threatening emergencies that require immediate Veterinary action; to delay can be to die. A dog can go from being "off" to dead within 24 hours. Symptoms of a sick nervous system, such as trouble walking, seizures, drooling, confusion, lethargy, etc, should never be ignored in an MDR1 dog.
Dr. Katrina Mealey of Washington State University's Veterinary Clinical Pharmacology Laboratory is the research pioneer and authority on this disease and will consult on emergencies for dogs that have been tested through their lab. To give our Carrier puppies the best chance at a full recovery, should they need it, we want this option to be available to our puppy owners, so we test every puppy through WSU before they ever go home.
Running this test on our litters gives us valuable information about what our dogs are producing, but more importantly, it gives both us and our puppy families peace of mind that the testing has already been taken care of and there is a plan and support already in place.
As breeders, we have the Herculean task of breeding up and away from this hideous disease while maintaining genetic diversity, which is even more important in a small gene pool such as ours. We select our breeding dogs very carefully, making sure not to double up on this mutation, so that at worst, a puppy will inherit only 1 copy of the mutation. This can be challenging, as MDR1 is prevalent in every type of Collie breed. Our long-term goal is to produce an MDR1-free line of Scotch Collies without increasing the incidence of other diseases in the trade-off. Not easy, but not impossible, either.
Problem: Vision is essential to a dog's purpose and quality of life. Collies are notorious for eye problems. The two main eye diseases that we are concerned about are Collie Eye Anomaly (CEA) and Progressive Retinal Atrophy (PRA/rcd2). Both conditions can cause blindness; CEA usually onsets before a pup's first birthday, while PRA/rcd2 is much later, usually between 5 and 7 years of age, often long after a breeding dog has produced puppies.
Solution: Our goal is to produce Normal-eyed puppies that are free of genetic eye diseases. Our dogs get regular eye exams, and every puppy will have his exam by our board-certified veterinary ophthalmologist before he goes home. Owners are provided with a copy of the written exam report.
Rationale: CEA is everywhere in Collies, with the large majority being at least Carriers, and many, many dogs being Affected. Thankfully, CEA doesn't usually cause blindness; however, it is impossible to know ahead of time if a CEA At Risk dog will be affected by disease.
PRA/rcd isn't as common as CEA, but is a much worse disease. As this is a late onset disease, we could can unwittingly produce PRA-affected puppies before the sire or dam showed any symptoms, unless we test.
CEA and PRA/rcd2 are two eye diseases for which we can test DNA, but there are many, many more eye diseases that can't yet be tested. To ensure the best eye health for our puppies, they are examined by our Board-certified Veterinary Ophthalmologist at approximately 6 weeks of age. By doing their exams this early (8 weeks is the usual age for this exam), their Veterinarian is able to catch any eye diseases before their eyes have a chance to "go normal" and give a false impression of their true eye health.
To note: There is a fair amount of confusion when it comes to health testing the eyes. "Normal-eyed" refers to the results of a physical exam, while "CEA" and "PRA/rcd2" are references to DNA testing. Physical exams are essential, both annually for adult dogs and in the diagnostic window for puppies, as so few eye diseases can be tested through DNA.
Hip & Elbow Dysplasia (CHD & ED)
Problem: Joint disease of the hip and elbow can be debilitating for dogs, financially significant for owners, and physically, mentally, and emotionally taxing for the whole family.
Solution: We test our dogs's hips through PennHip, which is an objective measurement of the hip joint. This test measures joint laxity (how "loose" a joint is), with the idea that the looser the joint, the more potential for hip dysplasia. Our goal is to learn what our starting point is with our dogs' hips, and to improve from there. We are testing hips and paying special attention to flooring and all contact surfaces. Traction in the whelping box, traction in the weaning pen, and smart exercise will all help to keep any hip dysplasia genetics in check, giving them a much better quality of life.
Rationale: When people ask about hip testing, "It's not a problem in our breed," is a common response. If you go strictly by numbers, it can definitely seem that way as about 2.8% of Collie hip x-rays are determined to be dysplastic, which is not terribly afflicted as a population.
But here's the problem: the number of Collies tested through OFA since they started reading hip x-rays in the 60's works out to approximately one Collie each week. Statistically, that's not even a sample that we could draw a reasonable conclusion, so we can't say with any confidence, based on those numbers, whether or not hip dysplasia is a problem for Collies. We just don't know enough.
In general, the Scotch Collie works as a farm dog more frequently that his Rough cousin. Sound structure is important for every dog, but it's a non-negotiable for a working dog. The dog's structure must be able to withstand the demands of his purpose.
That said, research shows that genetics plays only a small part in whether or not a dog will develop hip dysplasia; environmental factors may be up to 80% of the cause of the disease. What's even more interesting is that the whelping box itself may be part of the disease process. When the whelping box is slippery, like with a blue plastic kiddie pool, there isn't any resistance for a puppy's delicate bones and joints, and so they slip and slide in unnatural ways. We've seen how a puppy will rest on his knees when nursing on a slippery surface, which is horrible for their joints. With traction, pups have enough grip and resistance to stay on their feet, which is the correct nursing posture.
On a side note: our beloved Newfoundland girl, Tess, had some of the worst hips that our veterinarian neighbor had ever seen in her career. "Well, at least she's happy..." she said. Tess was a finished champion, fit and on the lean side, and incredibly athletic - until she wasn't. Our experience with hip dysplasia was such a painful one. So yes, this is personal for us.
Cyclic Neutropenia (CN) / Gray Collie Syndrome (GCS)
Problem: Autosomal recessive disease of the white blood cells. Dogs experience disease cycles for two weeks on/two weeks off and they are severely sick when sick. Many CN dogs die shortly after birth; those who survive, usually pass away by their second birthday.
Solution: Genetic testing for all breeding dogs.
Rationale: Our goal is two-fold: to avoid this horrible disease and to preserve genetic diversity; we will consider appropriate mates that are a genetic complement to our dogs. Puppies will be either n/n (Clear), n/M (Carrier), or a combination of the two.
Degenerative Myelopathy (DM)
Problem: This disease is degenerative and progressive. It begins in the rear assembly with subtle gait problems, then progresses eventually to a rear assembly that doesn't work, incapacitating the dog. Most are euthanized.
Solution: We require this test for all breeding dogs, and include it in the panel of tests we give to pups before they go home. We are shooting for Clear and Carrier puppies in order to avoid disease while maintaining genetic diversity.
Rationale: There is no cure for DM. Dogs affected by this disease aren't able to live out their lives or fulfill their purpose. It is mentally, emotionally, financially, and physically draining for owners to care for a dog with moderate to severe disease, only to have to eventually euthanize them. While DM is not physically painful for them, there is a heavy toll for both owner and dog as he progressively loses the ability to control his body.
Problem: Dermatomyositis causes lesions on the face, head, ears, legs, and tail. It can be painful and include muscle loss as well.
Solution: We test our dogs through Clemson University in South Carolina, and plan our breedings to minimize the risk for puppies developing this disease.
Rationale: DMS can be painful for the dog and limiting, especially if severely affected. It is draining for owners with time, energy, finances, and emotions as they work to help their dogs maintain as much quality of life as possible.
Problem: HUU is an inherited disease of the urinary system.
Solution: We test our dogs for this disease, and plan our breedings accordingly. Our goal is to produce HUU Clear puppies.
Rationale: HUU can cause crystals to form in the urinary tract. In severe cases, the crystals can be so large that they cause a total blockage of the urethra, putting the dog at risk for even more health issues.
VonWillebrand's Disease Type 2 (VWDii)
Problem: This is an anti-clotting defect of the dog's blood. It is an inherited Autosomal recessive disease.
Solution: We test every dog and puppy for this disease. Because it's an autosomal recessive, it's easy to avoid vWD Affected puppies. Our goal is to produce dogs that are either Clear or Carrier in order to avoid disease while maintaining genetic diversity.
Rationale: Because blood doesn't clot adequately, simple injuries and routine surgical needs are especially risky for these dogs.
Merle (M Locus)
Problem: "Merle" is complex mutation affecting coat color, with the potential to damage hearing and vision of pups if the mutation is not tested and properly matched in breedings.
Solution: We test our dogs to know if they have any of the mutation, and use this information to carefully plan our breedings.
Rationale: Merle is not a "yes" or "no" situation, like an autosomal recessive. Rather, it is a continuum, with non-Merle being on one end and Harlequin being all the way to the other.
The proper Merle notations, terms, and their base pair ranges are listed in the table below, thanks to the work of Langevin, et al. Tilia Laboratories (formerly Vemodia) in the Czech Republic is the only lab in the world that offers this level of accuracy in Merle diagnostics.
|Mc+||Cryptic Merle +||231-246|
|Ma+||Atypical Merle +||255-264|
For a specific group of dogs, this mutation isn't visible (especially for second owners, or if the dog has no known history), so we can't count on the dog's appearance to safely breed. Merle breeds must be bred with great care, as breeding the wrong base pair combinations creates the possibility of producing major defects with hearing, vision, and other body systems.
Merle content reviewed by Mary Langevin, author, The Incredible Story of Merle.
Loving a dog has uncountable rewards, but it's not without risk. There are many diseases and conditions that we don't yet have specific tests for. These are often autoimmune in nature and include allergies, cancer, collie nose, epilepsy, lupus (DLE/SLE), and literally a hundred others.
Breeders have made great strides in preventing inherited diseases, but we haven't been able to work on autoimmune diseases in a similar way until recently.
Genetic diversity testing is a new tool in the toolbox to help breeders improve the health of their puppies. Its main goal is to preserve and improve the health and well being of breeds, especially those with small populations.