GENETIC DISEASES
The following genetic disorders have been reported in Scotties:
Scottish Terrier Genetic Disorders
Von Willebrand’s Disease (vWD)
This serious blood clotting disorder was previously recognized in the Scottie but today is rarely seen thanks to the widespread use of a DNA test to identify the mutation. Used by all reputable breeders before producing their litters, this cheek swab test identifies the Affected individual (having both copies of the mutated gene), the Carrier individual (having one copy of the mutated gene and one normal copy but not showing signs of the disease), and the Clear individual (having two normal copies of the genes). Affected dogs are removed from the breeding program, and the carrier dogs are monitored closely and eventually retired from breeding. This strategy has resulted in the near elimination of the disease in litters today. If you are looking for a Scottie pup, always ask the breeder for evidence that parents are free of the vWD mutation.
The vWD DNA test is a requirement for Scottie CHIC Certification.
Scottie Cramp
Scottie Cramp is not actually a muscle “cramping” disorder, nor is it a seizure. Cramp is a genetic dysfunction of the chemical neurotransmitter made by the nerves that control the dog’s muscles. Affected Scotties are normal at rest and exhibit normal ability to walk until they become excited. After several minutes of strenuous activity and/or excitement, an affected dog may arch its back, walk stiffly, become immobilized, and may even roll to its side. A short while after the stimulation abates, the dog will recover and appear completely normal.
Scottie Cramp is a non-painful, episodic disorder, not constantly present; nor does it compromise the dog’s quality or length of life. Many affected dogs learn to manage the problem on their own and will stop running before symptoms appear. Sometimes an affected dog that is only leash-walked or that never has the opportunity to run strenuously will fail to exhibit clear symptoms at all.
In 2024, the HTF funded a project at the Canine Genetic Laboratory in Columbia, MO to search for the responsible mutation. As yet, there is no DNA test available, but research is ongoing. The incidence of Scottie Cramp has dramatically decreased in litters where the breeders carefully research and avoid the pedigrees with a history of this disorder.
Cerebellar Abiotrophy (CA)
CA is an uncommon neurologic disorder caused by a genetic mutation leading to gradual death of special “Purkinje” nerve cells in the cerebellum, the part of the brain that coordinates movement. Scotties with CA are born without symptoms of this disorder, but after a few months, or even years in some cases, they begin to develop a wobbly gait, incoordination, and the inability to run smoothly or to navigate stairs. CA is not a painful disease, nor does it cause weakness or affect the mental abilities of the dog. But CA is ever-present, usually progressing over the life of the dog. CA does affect the quality but not necessarily the length of life. Although a genetically-based test is not yet available, research on this genetic disorder is ongoing. While it was initially thought that this disorder is inherited in a straightforward way, similar to Scottie Cramp, research now suggests otherwise. Until the exact mutation for CA is discovered and a test is available, the best policy for breeders is to avoid any bloodlines where this disorder has occurred.
Craniomandibular Osteopathy (CMO)
Thankfully rare in the Scottie, CMO is a genetic disease of the bones of the jaw, typically seen in the 4-7-month-old pup. The disorder causes over-growth and painful swelling in the lower jaw. The puppy may be feverish, reluctant to open the mouth or to eat. A diagnosis of CMO is confirmed by a veterinarian using x-ray analysis. This disorder is transient and can be successfully treated with appropriate medication. As of 2018, a DNA test is available to identify Affected, Carrier and Clear individuals. With this tool, breeders are able to avoid this disease entirely in their programs.
The CMO DNA test is a requirement for Scottie CHIC Certification.
Liver Shunt (Portosystemic Shunts)
The liver has many vital roles, including regulating blood sugar, breaking down and removing toxins, and storing essential nutrients, among others. When a liver shunt is present, nutrient rich blood is diverted either around or through the liver, thereby depriving liver cells of components essential for their normal growth and function. Liver shunts can arise in any purebred or mixed breed dog. They go by many different names, but the underlying issue is a mutation or mutations that causes blood to bypass the liver through abnormal blood vessels. Liver shunts have been reported in a few Scotties, and this disorder continues to appear occasionally in certain lines.
Most of what is known about liver shunts in dogs comes from research done on Yorkshire Terriers, a breed where this problem is widespread due to the repeated use of shunt producers and carriers over many generations. And yet, despite years of painstaking research, the mutation(s) involved in this disorder and the mode of inheritance have not been identified.
Liver shunts can be detected early in puppies or they can emerge later in life in the adult dog. Puppies born with a liver shunt are typically small, weak and unthrifty. Build-up of nitrogenous wastes in the blood can cause bizarre neurological behavior, especially after eating. The diagnosis is made through a bile acid test that assesses the function of the liver. Follow-up ultrasound examination will reveal the abnormal shunting of blood flow and confirm the location and type of shunt. Surgery may correct the condition, depending on the location of the shunt or shunts, but this procedure requires great skill and is very expensive. As it is not possible to predict which dog will produce an affected puppy or which dog will carry the genetic mutations that will be passed along to the next generations, geneticists recommend that dogs who have produced offspring with liver shunts should not be bred again, and the siblings of an affected dog should also be spayed/neutered.
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