Genetic Disease & Color Testing for the Miniature American Shepherd Breed:
Why is genetic disease testing important?
Here at PreciousGem I strive to ensure healthy, quality Miniature American Shepherd (Mini Australian Shepherd) puppies. A very important role in being a responsible breeder and improving the breed means testing for common genetic diseases. It is my responsibility to have an understanding of the genetic make-up of my breeding dogs when testing is readily available for many diseases. Otherwise, a breeder may accidentally pair parents together that produce puppies with a life-long disease or condition that was entirely preventable.
What genetic tests do I recommend for breeding dogs?
To put it shortly, I recommend a full genetic panel that includes as many breed specific tests as possible plus coat color and other traits that can impact or improve breeding decisions.
To elaborate, these are the genetic tests that I feel are the bare minimum for a breeder:
- CEA, PRA, MDR1, HC, CD, DM, CDDY, and NAD.
However, I would ALSO like to see breeders testing for other diseases and traits such as:
- HUU, Non-HSF4 Cataracts, CMR1, CDPA, IVDD
- Color tests include: M locus (including merle length), S locus (piebald), D locus (dilute), E locus (yellow)
To elaborate, these are the genetic tests that I feel are the bare minimum for a breeder:
- CEA, PRA, MDR1, HC, CD, DM, CDDY, and NAD.
However, I would ALSO like to see breeders testing for other diseases and traits such as:
- HUU, Non-HSF4 Cataracts, CMR1, CDPA, IVDD
- Color tests include: M locus (including merle length), S locus (piebald), D locus (dilute), E locus (yellow)
Which testing laboratories do I recommend?
FULL COMPREHENSIVE PANEL
I currently recommend testing potential breeding dogs through AKC DNA + Health Kit which is processed by Neogen (formerly Canine Health Check panel). This includes a lengthy panel including MANY diseases and traits that are helpful when making breeding decisions. They have also shown to have fewer mistakes than other laboratories over the years. I am particularly interested in their "Social Attraction" test which is included.
AKC DNA + Health Kit by Neogen:
www.akc.org/breeder-programs/dna/dna-resource-center/akc-dna-health/
AKC DNA + Health Kit by Neogen:
www.akc.org/breeder-programs/dna/dna-resource-center/akc-dna-health/
INDIVIDUAL TESTING
If you are looking for individual testing without needing a full panel, consider these laboratories. UC Davis is recommended for merle length testing.
UC Davis: vgl.ucdavis.edu/dna-tests/dog
Animal Genetics: animalgenetics.com/canine-services/
GenSol: www.gensoldx.com/dogs/
UC Davis: vgl.ucdavis.edu/dna-tests/dog
Animal Genetics: animalgenetics.com/canine-services/
GenSol: www.gensoldx.com/dogs/
NAD and Non-HSF4 CATARACTS
NAD or Neuroaxonal Dystrophy is a recently discovered and horrific disease found in Miniature American Shepherds, Mini Australian Shepherds, and Toy Australian Shepherds. Testing has only recently become available and I highly recommend testing through Purdue who discovered the gene. They also recently discovered Non-HSF4 Cataracts in Mini American Shepherds.
Purdue ADDL Lab: vet.purdue.edu/addl/canine-genetics.php
Purdue ADDL Lab: vet.purdue.edu/addl/canine-genetics.php
How is a gene passed from parent to offspring?
The following chart is a Punnet Square which demonstrates the probability of a genetic trait being passed down from the parents to the offspring, particularly with a recessive trait. It is important to understand that a dog can still be a "carrier" of a recessive allele or disease and be bred - AS LONG AS they are not bred to another carrier. If a carrier dog is bred with another carrier, there is roughly a 25% chance that cross will produce puppies that are now expressing this trait or disease because they inherited two copies of the gene.
MDR1 (Multi-Drug Resistance Gene)
The MDR1 gene mutation affects how a dog’s body processes certain medications. Dogs with this mutation may have serious reactions to drugs that are normally safe for most dogs.
Medications that may be affected include some parasite preventatives, chemotherapy drugs, and sedatives. Dogs with the mutation may experience symptoms such as neurological problems, tremors, weakness, or severe illness if exposed to certain medications.
Genetic testing allows owners and veterinarians to know if a dog carries this mutation so that unsafe medications can be avoided.
Click HERE for further information about MDR1:
Medications that may be affected include some parasite preventatives, chemotherapy drugs, and sedatives. Dogs with the mutation may experience symptoms such as neurological problems, tremors, weakness, or severe illness if exposed to certain medications.
Genetic testing allows owners and veterinarians to know if a dog carries this mutation so that unsafe medications can be avoided.
Click HERE for further information about MDR1:
NAD (Neuroaxonal Dystrophy)
Neuroaxonal Dystrophy (NAD) has been affecting the breed for a long time but only recently has a test been developed through extensive research. NAD is a neurological disease that affects the brain and spinal cord. It has been identified in Miniature American Shepherd, Mini Australian Shepherd, and Toy Australian Shepherd. Other forms of NAD exist in different breeds.
Affected dogs typically begin showing signs as young adults, often between 2 and 4 years of age. Early symptoms may include abnormal gait, hind limb weakness, or difficulty climbing stairs. Over time the condition gradually worsens as nerve cells degenerate, which can eventually affect coordination and movement. This typically affects the dog's quality of life and causes a shorter life span due to neurological complications.
NAD is inherited in an autosomal recessive pattern, meaning a dog must inherit two copies of the mutation to develop the disease. Genetic testing is so important for breeders to make sure they are not breeding to carriers together.
Affected dogs typically begin showing signs as young adults, often between 2 and 4 years of age. Early symptoms may include abnormal gait, hind limb weakness, or difficulty climbing stairs. Over time the condition gradually worsens as nerve cells degenerate, which can eventually affect coordination and movement. This typically affects the dog's quality of life and causes a shorter life span due to neurological complications.
NAD is inherited in an autosomal recessive pattern, meaning a dog must inherit two copies of the mutation to develop the disease. Genetic testing is so important for breeders to make sure they are not breeding to carriers together.
CEA (Collie Eye Anomaly)
Collie Eye Anomaly is an inherited eye condition that affects the development of structures inside the eye. The severity can vary widely.
Some dogs show only mild changes in the eye and have normal vision, while more severe cases may develop:
Some dogs show only mild changes in the eye and have normal vision, while more severe cases may develop:
- vision impairment
- retinal detachment
- bleeding within the eye
PRA (Progressive Retinal Atrophy)
Progressive Retinal Atrophy is an inherited diseases that cause gradual degeneration of the retina, the light-sensitive tissue at the back of the eye.
Affected dogs typically experience progressive vision loss, often beginning with night blindness and eventually progressing to complete blindness. The disease usually develops later in life and currently has no cure.
Affected dogs typically experience progressive vision loss, often beginning with night blindness and eventually progressing to complete blindness. The disease usually develops later in life and currently has no cure.
HC (Hereditary Cataracts)
Hereditary Cataracts are an inherited form of cataracts that cause clouding of the lens of the eye. This cloudiness can interfere with normal vision and may progress over time.
The severity varies from mild changes that cause little vision impact to more advanced cataracts that may result in significant vision loss.
The severity varies from mild changes that cause little vision impact to more advanced cataracts that may result in significant vision loss.
DM (Degenerative Myelopathy)
Degenerative Myelopathy is a progressive neurological disease affecting the spinal cord, most often seen in adult or senior dogs. The condition gradually affects the nerves responsible for movement in the hind limbs. Signs can present from 6 months to 2 years. It is not entirely understood how the disease is inherited. Early signs may include:
- weakness in the rear legs
- difficulty standing or walking
- dragging of the feet
CD (Cone Degeneration)
Cone Degeneration is an inherited eye disorder that affects the cone cells of the retina, which are responsible for vision in bright light and color perception. Dogs affected by cone degeneration typically have difficulty seeing in daylight and bright conditions but may see better in low-light environments. Signs often appear early in life.
CDDY (Chondrodystrophy)
CDDY is a genetic variant associated with shorter legs and an increased risk of intervertebral disc disease (IVDD) in some dog breeds.
While the mutation contributes to the shorter leg structure seen in certain breeds, it may also increase the likelihood of spinal disc problems later in life.
I have yet to hear of a Miniature American Shepherd developing IVDD due to having one copy of CDDY (or 2 copies for that matter), but I would not recommend breeding two carrier parents together that could produce a puppy with two copies.
While the mutation contributes to the shorter leg structure seen in certain breeds, it may also increase the likelihood of spinal disc problems later in life.
I have yet to hear of a Miniature American Shepherd developing IVDD due to having one copy of CDDY (or 2 copies for that matter), but I would not recommend breeding two carrier parents together that could produce a puppy with two copies.
HUU (Hyperuricosuria)
Hyperuricosuria (HUU) is a genetic condition that affects how a dog processes uric acid, a natural waste product produced by the body. Dogs affected by HUU are more likely to develop urinary stones (uroliths) in the bladder or urinary tract. These stones can cause symptoms such as:
A dog must inherit two copies of the recessive mutation to be at significant risk for developing the condition.
- difficulty urinating
- blood in the urine
- urinary blockages
- discomfort or pain
A dog must inherit two copies of the recessive mutation to be at significant risk for developing the condition.
Merle (M locus)
The merle gene creates the mottled or marbled coat patterns seen in blue merle and red merle dogs. This gene affects pigment distribution throughout the coat and sometimes the eyes.
When a dog inherits two copies of the merle gene (double merle), pigment is deleted causing more white in the coat. Along with pigment deletion, the risk of serious health issues increases significantly. I mention the risks of double merle dogs above.
More recently, research by Mary Langevin and colleagues (Langevin et al., 2018) has shown that the merle gene can exist in multiple forms and lengths, which may influence how strongly the pattern is expressed. This research has helped improve genetic understanding of merle inheritance and its associated risks, particularly with merle lengths that are more likely to produce white and therefore cause vision and hearing impairments. Understanding merle lengths and how they interact helps a breeder make better pairing decisions.
Merle lengths include Mc, Mc+, Ma, Ma+, M, and Mh depending on the basepair numbers of the gene.
See more about Mary's research HERE!
When a dog inherits two copies of the merle gene (double merle), pigment is deleted causing more white in the coat. Along with pigment deletion, the risk of serious health issues increases significantly. I mention the risks of double merle dogs above.
More recently, research by Mary Langevin and colleagues (Langevin et al., 2018) has shown that the merle gene can exist in multiple forms and lengths, which may influence how strongly the pattern is expressed. This research has helped improve genetic understanding of merle inheritance and its associated risks, particularly with merle lengths that are more likely to produce white and therefore cause vision and hearing impairments. Understanding merle lengths and how they interact helps a breeder make better pairing decisions.
Merle lengths include Mc, Mc+, Ma, Ma+, M, and Mh depending on the basepair numbers of the gene.
See more about Mary's research HERE!
Dilute (D locus)
The dilute gene affects how pigment is distributed within the hair shaft, resulting in lighter coat colors such as blue (dilute black) or lilac shades. Dogs that inherit two copies of the dilute gene may have an increased risk of a condition known as Color Dilution Alopecia (CDA). This condition can cause:
Picture credit to https://color.ashgi.org/color/dilute_aussies.htm
- thinning hair or patchy hair loss
- brittle or fragile coat texture
- increased susceptibility to skin infections
Picture credit to https://color.ashgi.org/color/dilute_aussies.htm
Piebald / White Spotting (S locus)
The piebald gene controls the amount and distribution of white markings on a dog’s coat.
Dogs that inherit two copies of certain piebald variants may develop very large areas of white, particularly on the head and ears. As has been mentioned previously, when pigment cells are absent in parts of the inner ear, this can increase the risk of congenital deafness. Understanding if a dog carries for piebald helps a breeder reduce the likelihood of producing extreme white patterns.
Picture credit to https://coatsandcolors.com/s-locus-white-spotting-piebald/
Dogs that inherit two copies of certain piebald variants may develop very large areas of white, particularly on the head and ears. As has been mentioned previously, when pigment cells are absent in parts of the inner ear, this can increase the risk of congenital deafness. Understanding if a dog carries for piebald helps a breeder reduce the likelihood of producing extreme white patterns.
Picture credit to https://coatsandcolors.com/s-locus-white-spotting-piebald/
Yellow (E locus)
The E locus controls whether a dog can produce black-based pigment (eumelanin) in the coat.
When a dog inherits two copies of the recessive yellow gene (e/e), the coat may appear cream, yellow, or pale red regardless of the underlying color genetics.
In breeds such as the Miniature American Shepherd and the closely related Australian Shepherd, this color can sometimes mask other genetic traits such as merle. Because merle may not be visibly expressed in these dogs, careful genetic testing is important to prevent accidental merle-to-merle breedings. Therefore, yellow is not a color that is within the breed standard for Miniature American Shepherds and related breeds.
Picture credit to https://www.ashgi.org/home-page/genetics-info/coat-color/sable-and-yellow
When a dog inherits two copies of the recessive yellow gene (e/e), the coat may appear cream, yellow, or pale red regardless of the underlying color genetics.
In breeds such as the Miniature American Shepherd and the closely related Australian Shepherd, this color can sometimes mask other genetic traits such as merle. Because merle may not be visibly expressed in these dogs, careful genetic testing is important to prevent accidental merle-to-merle breedings. Therefore, yellow is not a color that is within the breed standard for Miniature American Shepherds and related breeds.
Picture credit to https://www.ashgi.org/home-page/genetics-info/coat-color/sable-and-yellow
Ready to learn about OFA Testing??
Check out the article about OFA testing and what I recommend HERE: