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The Australian Shepherd Disease Panel

 

Autosomal Recessive

(Need to inherit 2 copies to be affected)

 

Collie Eye Anomaly

Collie Eye Anomaly (CEA), also known as choroidal hypoplasia (CH), is an inherited disease affecting several dog breeds including the Australian shepherd. 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. Therefore, predicting the potential severity of the disease in an affected puppy is difficult as mildly affected parents may produce offspring that are severely affected.

 

Degenerative Myelopathy

Degenerative Myelopathy caused by Mutation of the SOD1 gene is an inherited neurologic disorder of dogs. This mutation is found in many breeds of dog, including the Australian shepherd. While it is not clear for some of the other breeds, Australian shepherds are known to develop degenerative myelopathy associated with this mutation. The variable presentation between breeds suggests that there are environmental or other genetic factors responsible for modifying disease expression. The average age of onset for dogs with degenerative myelopathy is approximately nine years of age. The disease affects the White Matter tissue of the spinal cord and is considered the canine equivalent to amyotrophic lateral sclerosis (Lou Gehrig’s disease) found in humans. Affected dogs usually present in adulthood with gradual muscle Atrophy and loss of coordination typically beginning in the hind limbs due to degeneration of the nerves. The condition is not typically painful for the dog, but will progress until the dog is no longer able to walk. The gait of dogs affected with degenerative myelopathy can be difficult to distinguish from the gait of dogs with hip dysplasia, arthritis of other joints of the hind limbs, or intervertebral disc disease. Late in the progression of disease, dogs may lose fecal and urinary continence and the forelimbs may be affected. Affected dogs may fully lose the ability to walk 6 months to 2 years after the onset of symptoms. Affected medium to large breed dogs, such as the Australian shepherd, can be difficult to manage and owners often elect euthanasia when their dog can no longer support weight in the hind limbs.

 

Hyperuricosuria

Hyperuricosuria is an inherited condition affecting Australian Shepherds. The SLC2A9 gene codes for a protein that allows the kidneys to transport uric acid from the urine. Dogs with mutations in both copies of the SLC2A9 gene are predisposed to have elevated levels of uric acid in the urine, hence the name hyperuricosuria. Uric acid can form crystals and/or stones (uroliths) in the urinary tract. Dogs with hyperuricosuria most commonly present with symptoms of recurrent urinary tract inflammation, which include frequent urination, blood in the urine, and straining to urinate. They may also have loss of appetite, lethargy, weakness, vomiting and pain. Urinary stones in the bladder can cause urinary tract infections or more seriously, blockage of the Urethra. Both male and female dogs can be affected, but obstruction of urine flow is more common in males due to differences in anatomy. Although an x-ray can be used to exclude other types of stones, urate stones cannot typically be seen using x-rays and must be evaluated by ultrasound. Not all dogs with mutations in both copies of the SLC2A9 gene will have symptoms of disease, though they will have increased uric acid excretion in the urine.

Intestinal cobalamin malabsorption (Australian shepherd type)

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Intestinal cobalamin malabsorption (Australian shepherd type)

Intestinal cobalamin malabsorption (Australian shepherd type) is an inherited disease affecting Australian shepherds. Affected dogs are unable to make adequate amounts of a protein that plays a role in absorption of certain nutrients from the intestinal tract and kidneys, including the B vitamin, cobalamin. Affected dogs have increased levels of methylmalonic acid in their urine (a sign of cobalamin deficiency) after weaning, but symptoms of disease may not be recognized by owners for months or years. Symptoms of disease include anorexia, lethargy, poor weight gain, poor muscle mass, and in rare circumstances, a severe neurological dysfunction called hepatic encephalopathy that can lead to altered mental state, seizures, coma and death. Affected dogs have an increase in certain proteins in their urine, and have decreased synthesis of blood cells resulting in Anemia and decreased numbers of neutrophils. Affected dogs require cobalamin supplementation for life that results in disease remission for most animals within a few weeks. Though not associated with clinical disease, affected dogs will continue to pass increased amounts of certain proteins in the urine even with cobalamin supplementation.

 

Intestinal cobalamin malabsorption (border collie type)

Intestinal cobalamin malabsorption (border collie type) is an inherited disease affecting dogs. Affected dogs are unable to make adequate amounts of a protein that plays a role in absorption of certain nutrients from the intestinal tract and kidneys, including the B vitamin, cobalamin. Affected dogs have increased levels of methylmalonic acid in their urine (a sign of cobalamin deficiency) from as early as 14 weeks of age, but symptoms of disease may not be recognized by owners for months or years. Symptoms of disease include anorexia, lethargy, poor weight gain, poor muscle mass, and in rare circumstances, a severe neurological dysfunction called hepatic encephalopathy that can lead to altered mental state, seizures, coma and death. Affected dogs have an increase in certain proteins in their urine, and have decreased synthesis of blood cells resulting in Anemia and decreased numbers of neutrophils. Affected dogs require cobalamin supplementation for life that results in disease remission for most animals within a few weeks. Though not associated with clinical disease, affected dogs will continue to pass increased amounts of certain proteins in the urine even with cobalamin supplementation.

 

Multifocal Retinopathy 1

Multifocal Retinopathy 1 is an inherited disorder of the Retina affecting Australian Shepherds. Affected dogs typically present between 11 and 16 weeks of age with multiple discrete circular areas of retinal detachment with underlying fluid accumulation that are visible on an eye exam performed by a veterinarian. These blister-like lesions are typically found in both eyes and can appear gray, tan, orange or pink and vary in number, size and location. Progression of retinal changes is usually slow and new lesions are not noted after 6 to 12 months of age. Occasionally as affected dogs age, lesions appear to heal and are no longer visible on an eye exam. Generally the dog’s vision is not affected although vision loss has been described in some cases of multifocal retinopathy 1.

 

Progressive retinal Atrophy

Progressive retinal Atrophy, progressive Rod-cone degeneration (PRA-prcd) is a late onset, inherited eye disease affecting Australian Shepherds. PRA-prcd occurs as a result of degeneration of both rod and cone type Photoreceptor Cells of the Retina, which are important for vision in dim and bright light, respectively. Evidence of retinal disease in affected dogs can first be seen on an Electroretinogram around 1.5 years of age for most breeds, but most affected dogs will not show signs of vision loss until 3 to 5 years of age or later. The rod type cells are affected first and affected dogs will initially have vision deficits in dim light (night blindness) and loss of peripheral vision. Over time affected dogs continue to lose night vision and begin to show visual deficits in bright light. Other signs of progressive retinal atrophy involve changes in reflectivity and appearance of a structure behind the retina called the Tapetum that can be observed on a veterinary eye exam. Although there is individual and breed variation in the age of onset and the rate of disease progression, the disease eventually progresses to complete blindness in most dogs. Other inherited disorders of the eye can appear similar to PRA-prcd. Genetic testing may help clarify if a dog is affected with PRA-prcd or another inherited condition of the eye.

 

Coagulation factor VII

Coagulation factor VII deficiency is an inherited bleeding disorder affecting dogs. Factor VII is an essential protein needed for normal blood clotting. Deficiency of this factor most commonly results in a mild bleeding disorder. An affected dog may bruise easily, have frequent nosebleeds, and exhibit prolonged bleeding after surgery or trauma. In rare cases, the bleeding may be severe. Due to the mild nature of this disorder, affected dogs may not be identified until a surgery is performed or trauma occurs at which time excessive bleeding is noted. Veterinarians performing surgery on dogs that are known to have coagulation factor VII deficiency should have ready access to blood banked for transfusions. Most dogs with this condition will have a normal lifespan despite increased blood clotting times.

 

Cone Degeneration

Cone Degeneration is an inherited eye disease affecting dogs. Affected dogs develop day blindness (blindness in bright light) and Photophobia (light sensitivity) between 8 to 12 weeks after birth due to degeneration of cells in the eye called cone photoreceptors which are responsible for vision in bright light. Affected dogs have normal vision in low light and structures of the inner eye appear normal on eye exam. Normal cone cell function can be seen on Electroretinogram (ERG) before six weeks of age, but becomes abnormal between 6 to 12 weeks of age and is completely absent in affected adult dogs signifying complete loss of Cone Cells. The cells responsible for vision in low light called Rod photoreceptors are not affected and thus, affected dogs will still be able to see normally in low light throughout life.

 

Exercise-induced collapse (EIC)

Exercise-induced collapse (EIC) is an inherited neuromuscular disorder affecting several breeds of dog. EIC presents as exercise intolerance in apparently healthy dogs. Affected dogs are usually diagnosed before two years of age and appear normal during low to moderately strenuous activity. However, shortly after 5-20 minutes of strenuous exercise affected dogs will begin to walk with a wobbly, uncoordinated gait that often only affects the hind limbs. Dogs remain mentally alert and are not in pain during episodes of EIC. In some circumstances, the symptoms of EIC can progress to full body weakness with low muscle tone (flaccid paralysis), confusion, loss of consciousness, seizures and very rarely, death. The episodes typically last 5-10 minutes and most dogs will completely recover within 15-30 minutes.

 

Neuronal ceroid lipofuscinosis 5 (NCL5)

Neuronal ceroid lipofuscinosis 5 (NCL5) is a lysosomal storage disease affecting Border Collies. Affected dogs lack adequate activity of a specific Enzyme necessary for normal cellular metabolism. As a result, there is an abnormal accumulation of waste compounds primarily in the cells of the nervous system, leading to a range of nervous system disorders. Affected dogs typically present between 15 and 20 months of age with behavioral changes. Symptoms initially include non-responsiveness to commands, loss of interest in play or other dogs, irrational fears, hallucinations, disorientation and aggression. Symptoms become more frequent and severe over time and may include Ataxia, falling, seizures, aimless wandering, abnormal gait, lethargy and vision loss. Dogs with this disease rarely live beyond 32 months of age.

 

Neuronal Ceroid Lipofuscinosis 6 (NCL6)

Neuronal Ceroid Lipofuscinosis 6 (NCL6) is a lysosomal storage disease affecting Australian Shepherds. Affected dogs lack a specific Enzyme necessary for normal metabolism. As a result, there is an abnormal accumulation of waste compounds primarily in the cells of the nervous system, leading to a range of nervous system disorders. Affected dogs present around 1.5 years of age with progressive neurologic disease. Symptoms include loss of vision, behavioral change, anxiety, lack of muscle coordination and abnormal gait. Affected dogs are often humanely euthanized by 2 years of age due to progression of the disease.

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Neuronal ceroid lipofuscinosis 8

Neuronal ceroid lipofuscinosis 8 (Australian shepherd type) is a lysosomal storage disease affecting Australian shepherds. Affected dogs lack a specific Enzyme necessary for normal cellular metabolism. As a result, there is an abnormal accumulation of waste compounds primarily in the cells of the nervous system, leading to a range of nervous system disorders. In affected dogs poor vision may be noticed as puppies, but by as early as 10-12 months of age symptoms of cognitive decline appear and may include loss of learned behaviors, circling, and pacing. Symptoms progress to blindness, Ataxia, behavior changes such as anxiety and aggression, tremors, sensitivity to touch and sound, and seizures by the time the dog is 2 years of age. Affected dogs are typically euthanized due to disease progression.

 

Von Willebrand disease type I (VWDI)

Von Willebrand disease type I (VWDI) is an inherited bleeding disorder affecting many breeds of dog. Dogs affected with VWDI have less than half of the normal level of von Willebrand coagulation factor (vWf), which is an essential protein needed for normal blood clotting. There is variability in the amount of vWf such that not all dogs with two copies of the Mutation are equally affected. Dogs that have less than 35% of the normal amount of vWf generally have mild to moderate signs of a bleeding disorder. Affected dogs may bruise easily, have frequent nosebleeds, bleed from the mouth when juvenile teeth are lost, and experience prolonged bleeding after surgery or trauma. Less often, the bleeding may be severe enough to cause death. Due to the variable severity of the disorder, affected dogs may not be identified until a surgery is performed or trauma occurs at which time excessive bleeding is noted. Veterinarians performing surgery on known affected dogs should have ready access to blood banked for transfusions. Most dogs will have a normal lifespan with this condition despite increased blood clotting times.

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