Health Testing in Shetland Sheepdogs
Shelties are a relatively healthy and hardy little dog, but there are several heritable disorders which owners and breeders should be aware of and which many breeders are now testing for.
We recommend for all breeding dogs a physical eye exam with an ophthalmologist (often performed as part of litter screening), DNA testing for breed specific diseases (see below) and hip and elbow scoring (which must be performed after 12 months of age).
DNA testing for shelties includes: Collie Eye Anomaly (CEA), Ivermectin Sensitivity (MDR1), Von Willebrands III (VWDIII), Degenerative Myelopathy (DM) and Juvenile Dermatomyositis (DMS) with more tests being added regularly.
Collie Eye Anomaly
Collie Eye Anomaly (CEA), also known as choroidal hypoplasia (CH), is an inherited disease affecting several dog breeds including the Shetland sheepdog. Breeders should be having puppies eye tested with a Veterinary Ophthalmologist between 6 and 8 weeks of age and a copy of these eye results should be provided to new puppy homes.
What is choroidal hypoplasia (CH aka CEA)? The choroid is the layer of tissue in the eye responsible for supplying blood and nutrients to the Retina. In dogs affected with CEA, the choroid does not develop properly and is therefore thinner than normal. The severity of the condition can vary from dog to dog. In mild cases, affected dogs may only show signs of collie eye anomaly on eye exam between about 5 and 12 weeks of age, just prior to normal, age-related pigmentation of the retina which often masks the characteristic, disease-related changes. After this time period, mildly affected dogs may be impossible to distinguish from normal dogs on eye exam (a phenomenon often referred to as “going normal”) and may not display obvious vision deficits. In more severely affected dogs, clinical signs include malformations of the eye and/or optic nerve (colobomas), retinal detachment, intraocular bleeding, and subsequent blindness. Both mild and severe forms of CEA are associated with the same NHEJ1 gene Mutation. (overview from pawprintgenetics.com)
Selective breeding and hard work by breeders over many generations means that Shelties in Australia are most often unaffected or only mildly affected for CEA.
Ivermectin Sensitivity (MDR1 or IVM)
Shelties can suffer adverse reactions to an anti-parasitic drug called Ivermectin. It has been discovered that some breeds of dog, mainly, but not exclusively varieties of Collie, are unable to produce a protein which is essential for pumping drugs and toxins out of the central nervous system. Ivermectin is just one of several drugs which are now known can cause this reaction and the condition is generally referred to as MDR1 because the protein responsible is known as the Multi-Drug Resistance protein. MDR1 is not a disease and as long as a dog with the sensitivity is not exposed to any of the dangerous drugs then it will not be at risk of a reaction. Both carriers (one copy of the gene) and affected dogs (2 copies) will have increased sensitivity to these drugs, so both should be treated as "affected" and these drugs avoided, or in the case of some drugs reduced doses used.
A list of those drugs and whether they are high or low risk to use can be found in the file below:
We recommend for all breeding dogs a physical eye exam with an ophthalmologist (often performed as part of litter screening), DNA testing for breed specific diseases (see below) and hip and elbow scoring (which must be performed after 12 months of age).
DNA testing for shelties includes: Collie Eye Anomaly (CEA), Ivermectin Sensitivity (MDR1), Von Willebrands III (VWDIII), Degenerative Myelopathy (DM) and Juvenile Dermatomyositis (DMS) with more tests being added regularly.
Collie Eye Anomaly
Collie Eye Anomaly (CEA), also known as choroidal hypoplasia (CH), is an inherited disease affecting several dog breeds including the Shetland sheepdog. Breeders should be having puppies eye tested with a Veterinary Ophthalmologist between 6 and 8 weeks of age and a copy of these eye results should be provided to new puppy homes.
What is choroidal hypoplasia (CH aka CEA)? The choroid is the layer of tissue in the eye responsible for supplying blood and nutrients to the Retina. In dogs affected with CEA, the choroid does not develop properly and is therefore thinner than normal. The severity of the condition can vary from dog to dog. In mild cases, affected dogs may only show signs of collie eye anomaly on eye exam between about 5 and 12 weeks of age, just prior to normal, age-related pigmentation of the retina which often masks the characteristic, disease-related changes. After this time period, mildly affected dogs may be impossible to distinguish from normal dogs on eye exam (a phenomenon often referred to as “going normal”) and may not display obvious vision deficits. In more severely affected dogs, clinical signs include malformations of the eye and/or optic nerve (colobomas), retinal detachment, intraocular bleeding, and subsequent blindness. Both mild and severe forms of CEA are associated with the same NHEJ1 gene Mutation. (overview from pawprintgenetics.com)
Selective breeding and hard work by breeders over many generations means that Shelties in Australia are most often unaffected or only mildly affected for CEA.
Ivermectin Sensitivity (MDR1 or IVM)
Shelties can suffer adverse reactions to an anti-parasitic drug called Ivermectin. It has been discovered that some breeds of dog, mainly, but not exclusively varieties of Collie, are unable to produce a protein which is essential for pumping drugs and toxins out of the central nervous system. Ivermectin is just one of several drugs which are now known can cause this reaction and the condition is generally referred to as MDR1 because the protein responsible is known as the Multi-Drug Resistance protein. MDR1 is not a disease and as long as a dog with the sensitivity is not exposed to any of the dangerous drugs then it will not be at risk of a reaction. Both carriers (one copy of the gene) and affected dogs (2 copies) will have increased sensitivity to these drugs, so both should be treated as "affected" and these drugs avoided, or in the case of some drugs reduced doses used.
A list of those drugs and whether they are high or low risk to use can be found in the file below:
mdr1_picture.jpg |
Von Wilebrands type III (vWDIII)
Von Willebrand disease (vWD) is the most comon inherited bleeding disorder found in dogs and humans. vWD inhibits the normal blood clotting process, causing prolonged bleeding after an injury. Von Willebrand's disease type III (VWDIII) is transmitted as an autosomal recessive trait, which means that only animals with 2 copies of the gene will be affected by the disease. Whilst this can be a very serious disease, the incidence of the gene in Australia is extremely low with even carriers being a rare finding, so it is easy to avoid producing affected puppies. (as of March 2020, from 750 shelties DNA tested through Orivet Genetics, 2.7% were found to be carriers of the disease, 0 affected dogs were tested, so >97% of the population is genetically clear of VWD).
Degenerative Myelopathy (DM or DGMY)
Degenerative Myelopathy (DM) is a disease affecting the spinal cord, resulting in slowly progressive hind limb weakness and paralysis, typically occurring in older dogs, between 8 and 14 years of age. It is a recessive gene, so only dogs with 2 copies of the gene may be affected, and those dogs are termed "at risk" and still not guaranteed to develop clinical disease. This is a common gene across many dog breeds, but only some breeds show a regular incidence of "at risk" individuals going on to develop clinical disease (such as German Shepherds and Bernese Mountain Dogs). It is not clear as to whether we are seeing any clinically affected Shelties in Australia at this stage, but this is still a gene that many breeders will test for and keep in consideration in their breeding dogs.
Juvenile Dermatomyositis (DMS)
Dermatomysitis (DMS) is an autoimmune disease with a genetic background and additional environmental triggers. Dermatomyositis symptoms appear in young dogs, usually by 6 months of age, but may appear as early as 7 to 11 weeks of age. The earliest clinical signs include crusting and scaling on the face, ears, tail tip, and across the bony prominences of the limbs and feet. In some cases, those symptoms weaken or disappear, and sometimes reappear during the life of a dog. The gold standard for the direct diagnosis of DMS is a skin biopsy.
The genetic test analyses three gene variants that help determine the risk for DMS. The complex multifactorial genetic trait needs an additional external trigger like vaccination or viral infection to cause symptoms of the disease. Stress-related factors are described to worsen the course of DMS.
See file below for the risk of different allele combinations. Note, in Australia testing is currently available for the A and B alleles.
Von Willebrand disease (vWD) is the most comon inherited bleeding disorder found in dogs and humans. vWD inhibits the normal blood clotting process, causing prolonged bleeding after an injury. Von Willebrand's disease type III (VWDIII) is transmitted as an autosomal recessive trait, which means that only animals with 2 copies of the gene will be affected by the disease. Whilst this can be a very serious disease, the incidence of the gene in Australia is extremely low with even carriers being a rare finding, so it is easy to avoid producing affected puppies. (as of March 2020, from 750 shelties DNA tested through Orivet Genetics, 2.7% were found to be carriers of the disease, 0 affected dogs were tested, so >97% of the population is genetically clear of VWD).
Degenerative Myelopathy (DM or DGMY)
Degenerative Myelopathy (DM) is a disease affecting the spinal cord, resulting in slowly progressive hind limb weakness and paralysis, typically occurring in older dogs, between 8 and 14 years of age. It is a recessive gene, so only dogs with 2 copies of the gene may be affected, and those dogs are termed "at risk" and still not guaranteed to develop clinical disease. This is a common gene across many dog breeds, but only some breeds show a regular incidence of "at risk" individuals going on to develop clinical disease (such as German Shepherds and Bernese Mountain Dogs). It is not clear as to whether we are seeing any clinically affected Shelties in Australia at this stage, but this is still a gene that many breeders will test for and keep in consideration in their breeding dogs.
Juvenile Dermatomyositis (DMS)
Dermatomysitis (DMS) is an autoimmune disease with a genetic background and additional environmental triggers. Dermatomyositis symptoms appear in young dogs, usually by 6 months of age, but may appear as early as 7 to 11 weeks of age. The earliest clinical signs include crusting and scaling on the face, ears, tail tip, and across the bony prominences of the limbs and feet. In some cases, those symptoms weaken or disappear, and sometimes reappear during the life of a dog. The gold standard for the direct diagnosis of DMS is a skin biopsy.
The genetic test analyses three gene variants that help determine the risk for DMS. The complex multifactorial genetic trait needs an additional external trigger like vaccination or viral infection to cause symptoms of the disease. Stress-related factors are described to worsen the course of DMS.
See file below for the risk of different allele combinations. Note, in Australia testing is currently available for the A and B alleles.
DMS Allele Risk List |
Hip Dysplasia and Elbow Dysplasia.
Hip and/or Elbow Dysplasia has been know to affect some Shelties. A number of breeders are now getting their breeding stock hip scored.
Both Hip and Elbow Dysplasia are polygenic diseases, which means that multiple genes and environmental factors (such as weight and early exercise) will influence the quality of a dogs hip and elbow conformation.
Hip scoring and Elbow scoring via xrays is our best way to screen the quality of our breeding dogs joints, and it is recommended that these xrays are performed by your vet after 12 months of age.
To see the live breed average hip and elbow scores for the last 5 years follow the link below:
http://orchid.ankc.org.au/Home/HipScores
Hip and/or Elbow Dysplasia has been know to affect some Shelties. A number of breeders are now getting their breeding stock hip scored.
Both Hip and Elbow Dysplasia are polygenic diseases, which means that multiple genes and environmental factors (such as weight and early exercise) will influence the quality of a dogs hip and elbow conformation.
Hip scoring and Elbow scoring via xrays is our best way to screen the quality of our breeding dogs joints, and it is recommended that these xrays are performed by your vet after 12 months of age.
To see the live breed average hip and elbow scores for the last 5 years follow the link below:
http://orchid.ankc.org.au/Home/HipScores