Collie Health Foundation Health Statement

Preservation of the Collie is the highest priority of a reputable, ethical breeder:  Every puppy born should be conceived with this tenet in mind.  It is the position of the Collie Health Foundation that no breeding should occur where there exists a known preventable or high risk of producing Collies with severe disabilities or poor quality of life.

Genetic testing allows Collie breeders to identify genetic markers known to produce disorders or disability and to use this knowledge to reduce risk when planning breedings.

The CHF highly recommends the following genetic screening tests as minimum for a good breeding program: CEA, MDR1, PRA-rcd2, and DMS. 

Testing can be classified by both genotype (heritable genes transferred from parents to offspring) or phenotype (observable physical properties) but it is important to understand that phenotype is created by the physical expression of one or more genes (interaction of the genotype and the environment) so they are not mutually exclusive.

See the Collie Health Foundation Website ( for a more thorough discussion of these conditions and tests.

Genetic Diversity

The dog species as a whole can be said to have wide phenotypic diversity based on physical characteristics, behaviors, etc., but as domestication becomes increasingly selective for specific characteristics in individual breeds of dogs, genetic diversity decreases.  As genetic gene pools become narrower in a specific breed, the risk of health issues – most especially complex disease, cancer, and autoimmune disorders – increases. In nature a species breeds for survival, thus the strongest and healthiest are privileged.  The area of genetic diversity and the impact on health has become a focus of research over the years as disease incidence has increased in certain breeds. One issue that decreases diversity is the selective breeding practices that help solidify “breed type” – creating homozygosity. This is not all bad. It can help maintain uniformity and “breed type.”  It is also possible to use genetic testing to select against harmful or disease expressing genes.  This is a delicate balance and knowledge of genetic diversity should be used purposefully to protect the Collie as a breed and promote its health. 

For further information see links below:

Genetic Tests

MDR1 (Multidrug Resistance 1 drug sensitivity) is an autosomal dominant genetic mutation that, when present, makes the natural barriers in the body more permeable.  This allows certain drugs to more readily cross the protective blood/brain barrier.  As a result, dogs can develop toxic levels of drugs, even at recommended doses, and severe neurological symptoms may occur depending on the drug, the dosage, and the severity of mutation. Many of these medications are used to treat a wide range of medical conditions (including pain, stress, or anxiety) in dogs. The mutation is especially prevalent in herding breeds. It is extremely important that a Collie’s MDR1 genetic marker status is known prior to administering any drug from the classifications known to be affected by MDR1.  Dosages can thus be monitored to minimize side effects and/or other treatments or drugs can be utilized.

The MDR1 test will identify a Collie’s MDR1 genetic marker status as either normal/normal, mutant/normal, or mutant/mutant. Both mutant/normal and mutant/mutant dogs have the defect, but, theoretically, the mutant/normal dog will express the condition less severely.  Over time, and with thoughtful breeding assisted by genetic testing information, the prevalence of affected Collies can be reduced and/or drug side effects minimized.

PRA (progressive retinal atrophy) is a group of degenerative diseases affecting the retina of the eye.  It is unrelated to Collie Eye Anomaly (CEA).  Fortunately, through a no-tolerance policy by breeders and strict testing, PRA is rare in Collies today. The unique type of PRA in Collies is designated as PRA-rcd2 – an autosomal recessive disorder that is characterized by early onset vision loss (typically symptomatic by 6 weeks and complete blindness by 6-8 months).  The PRA-rcd2 genetic test identifies if a Collie’s genetic marker is normal or if the Collie is a carrier or is affected. The PRA-rcd2 test is important to include in basic genetic testing because of the severity of the disease.  Additionally, it is critical that puppies have an eye examination by a Board Certified Veterinary Ophthalmologist to identify the beginning stages phenotypically.   

DMS (Dermatomyositis) refers to an inflammatory autoimmune disorder affecting skin and/or muscle and can vary from mild to severe. A combination of genetic and environmental factors are associated with the appearance of DMS symptoms. Environmental factors may include sun exposure, viral infections, air pollutants, etc.  A genetic 3 loci-gene DNA test helps determine the risk factors for developing DMS, but it is not definitive; thus it is also important that a skin biopsy be completed on any lesions that develop.  The test allows breeders to lower  genetic risk in offspring.

CEA (Collie Eye Anomaly) – See below

Other tests that may be done to ensure a healthy collie breeding outcome, include, but are not limited to, a complete Genetic Panel (that may include all or some of the tests for the disorders described above), hip radiographs (OFA or PennHip), Hypothyroidism, Canine Cyclic Neutropenia, and Degenerative Myelopathy (DM). 

Phenotype Health Testing

CEA  (Collie Eye Anomaly) refers to an autosomal recessive genetic mutation disorder of the inner structures of the eye found in most herding breeds, especially Collies and Shetland Sheepdogs.  The CEA genetic test does not replace the need for a physical eye examination done by a Board Certified Veterinary Ophthalmologist (typically @ 6-8 weeks old),  CEA generally does not worsen over time and does not cause vision defects unless the dog is severely affected. 

Hip and Elbow Screening  Orthopedic screening of breeding stock should be certified by either OFA or Penn-Hip.  This requires submission of X-rays to OFA or Penn-Hip. for evaluation and rating.

Merle to Merle Breedings

Merle in dogs manifests in both coat color patterns and genetic DNA allele markers. The genetic merle mutation  affects melanocytes that are found in the skin and coat, eye, inner ear, bone and heart.  The genetic merle allele was first identified in 2006. The gene involved may manifest differently (depending on allele loci sub-categories), thus causing varied coat pattern responses, including patterns that are visually subtle or “hidden”.  The merle (M) allele is considered dominant, so it only takes one copy to produce a merle dog. The non-merle allele (m) is recessive. There is both a dominant and recessive trait in the regular merle (Mm). A non-merle is designated mm. If two regular merles (Mm) are bred together it results in a potential for a double merle or “double dilute” designated as MM (Statistical risk – 25%). Merle to Merle breedings result in a high potential for microphthalmia (abnormally small eyes) and blindness, deafness, and loss of most coat and skin pigment. 

Finally, due to the high potential for deaf and/or blind offspring, the CHF cannot condone merle to merle breedings and therefore states that breeding a merle (sable or blue) Collie to another merle (sable or blue) Collie should be avoided due to the high risks of such breedings.

Collie Health Foundation Role

The Collie Health Foundation seeks out, supports, and sponsors research on major health concerns impacting the Collie and encourages breeders of purebred rough and smooth Collies to participate in such research. The CHF educates Collie breeders and owners on important health issues and serves as a health resource through sponsored seminars, website posts and articles, current research findings, and website links to pertinent health information. CHF supports and sponsors testing for CHF members through finding the best resources for reliable testing, seeking discounts, and establishing subsidies as able for those tests. CHF also supports the Martha E. Hoffman CHIC DNA Banking Project, sponsored by AKC Canine Health Foundation and Orthopedic Foundation for Animals. Collie Breeders who contribute to this project help preserve the future of the Purebred Collie. With the gene pool of all purebred dogs shrinking, the DNA bank will provide samples needed for genetic research projects at time of need, leading to better efficiencies and faster results. Donors will have access to their dogs’ DNA when new tests become available. In addition, CHF encourages Collie Breeders to obtain CHIC certification. See for special CHF member benefits regarding certification submission.

The Collie Health Foundation sponsors research and genetic testing for the purebred Collie and provides additional benefits for Foundation members. For more information, please go to TEST YOUR COLLIE.

Approved 1/9/2024 by the CHF Board of Directors.