Health Tests & Genetic Screening
We feel starting with physically healthy animals is important to reduce risk of health conditions or occurrence of known genetic diseases in the next generation. Below is some information about the health testing done for our relevant breeds. Follow the highlighted links to learn more.
Sealyham Terriers
We feel starting with physically healthy animals is important to reduce risk of health conditions or occurrence of known genetic diseases in the next generation. Below is some information about the health testing done for our relevant breeds. Follow the highlighted links to learn more.
Sealyham Terriers
- Primary Lens Luxation (DNA Test) - Primary lens luxation can be an inherited or acquired problem that is caused by the lens becoming dislodged. This results in glaucoma and cause persistent pain and blindness without prompt surgical intervention to remove the lens. The test distinguishes between clear, carrier and affected dogs. Clear dogs have no copies of the mutant gene and will neither develop the inherited condition nor pass the gene on to their offspring. Carrier dogs have one copy of the normal gene and one copy of the mutant gene and so will pass the mutant gene to approximately half of their offspring, although will not develop the disease themselves. Affected dogs have two copies of the mutant gene that causes the condition and have a high risk of developing the disease. Testing is required under the Assured Breeders Scheme.
- Eye Examination (BVA/KC/ISDS Eye Scheme) - The BVA/KC/ISDS Eye Scheme offers eye testing to screen for inherited eye disease. The aim of screening breeding stock is so breeders can eliminate or reduce the frequency of eye disease being passed on to puppies. Under the scheme a specialist canine ophthalmologists examines a dog to look for clinical signs of inherited disease known to affect the breed in question. If no clinical signs are noted for these diseases, then the dog is declared ‘Unaffected’. If signs consistent with one or more conditions are detected, then the dog will be declared ‘Affected’ for the relevant disease. In Sealyham Terriers, conditions examined for includes Primary Lens Luxation and Total Retinal Dysplasia. It is recommended that eyes are examined within 12 months of breeding, with the advice given to only breed from dogs that are found to be unaffected (or clear) of all known conditions in the breed. Examinations are required under the Assured Breeders Scheme.
- Chondrodystrophy (CDDY with IVDD Risk) and Chondrodysplasia (CDPA) - The test checks for two mutations: CDDY with IVDD Risk, and CDPA. Chondrodysplasia (CDPA) and Chondrodystrophy (CDDY) both contribute to a short legged phenotype (appearance) and are common in many dog breeds. The intervertebral disc, which sits between vertebrae, is composed of an outer fibrous basket made of 70% collagen and an inner gel-like layer called the nucleus pulposus. These structures allow for flexibility of the vertebral column. In Chondrodystrophic breeds (CDDY), premature calcification of the nucleus pulposus at early age (from birth to 1 year of age) results in degeneration of all discs in young dogs. These abnormal discs are predisposed to herniation into the spinal canal where the inflammation, and hemorrhage can cause severe pain and neurological dysfunction (myelopathy) termed Intervertebral Disc Disease or IVDD. The inheritance follows a dominant mode, meaning that 1 copy of CDDY mutation is sufficient to predispose dogs to IVDD. The CDDY mutation has not been found to specifically be of concern in Sealyham Terriers, however given the breed type and availability of the test we have decided to start testing for this gene. The currently known frequency of the allele (with a small sample size tested) is quite high so breeding away from the gene may be difficult to do.
- Degenerative Myelopathy (DM) - (also known as chronic degenerative radiculomyelopathy) is a progressive disease of the spinal cord in older dogs. The disease has an insidious onset typically between 7 and 14 years of age. It begins with a loss of coordination (ataxia) in the hind limbs, is chronic and progressive, and results in paralysis. Degenerative myelopathy initially affects the back legs and causes muscle weakness and loss, and lack of coordination. These cause a staggering effect that may appear to be arthritis. The dog may drag one or both rear paws when it walks, causing the nails of one foot to be worn down. The condition may lead to extensive paralysis of the back legs. As the disease progresses, the animal may display symptoms such as incontinence and have considerable difficulties with both balance and walking. If allowed to progress, the animal will show front limb involvement and extensive muscle atrophy. Eventually cranial nerve or respiratory muscle involvement necessitates euthanasia. Progression of the disease is generally slow but highly variable. The animal could be crippled within a few months, or may survive up to three years. If a dog has no copies or one copy of the gene, it is very unlikely that the dog will show signs of the Degenerative Myelopathy. If the dog has two copies of the gene it may or may not show signs of the disease. Although DM has not been identified as a concern in Sealyham Terriers, we have decided to begin testing our breeding stock for it to make informed breeding choices.
English Springer Spaniels
- Fucosiodiosis (DNA Test) - Canine Fucosidosis (Fuco) is a disease which is severe, progressive and ultimately fatal. It is characterised by deteriorating signs of the nervous system progressing over a period of months, sometimes from an early age. Symptoms include un-coordination, ataxia (loss of control of movement), change in temperament, loss of learned behaviour, loss of balance, apparent deafness, visual impairment and varying degrees of depression. The disease, which usually affects animals between 18 months and 4 years of age, is caused by a recessive mutation in the gene for the enzyme alpha-L-fucosidase. This enzyme is one of many required to break down complex compounds into simple molecules that the body can use. In affected dogs, those carrying two copies of the mutated gene, this enzyme is absent, the pathway is blocked and toxic compounds build up in the cells of the affected animal. The cells of the nervous system are particularly sensitive to these toxic intermediates.
- Progressive Retinal Atrophy cord-1 (DNA Test)- Generalised progressive retinal atrophy (gPRA) is a disease of the retina. This tissue, located inside the back of the eye, contains specialized cells called photoreceptors that absorb light focused on them by the eye’s lens, and converts this light into electrical nerve signals which are interpreted by the brain as vision. These photoreceptors are divided into two groups; the cones, which aid bright light and colour vision, and the rods, which facilitate low light or night vision. The cord-1 mutation is recessive mutation which causes both cone and rod degeneration resulting in initial night blindness, but usually progressing to total blindness in affected dogs. The effects of this mutation were initially believed to result in an early onset form of PRA, typically with an age of onset around two years of age, but more recent results show that some dogs with two copies of this mutation are not diagnosed until much later in life, sometimes as late as 10 years of age.
- Phosphofructokinase (DNA Test) - Phosphofructokinase (PFK) deficiency is an inherited disease which leads to a lack of the enzyme phosphofructokinase. Without this enzyme, muscle cells and erythrocytes (a type of blood cell) are not able to produce enough adequate energy for their needs. Therefore affected dogs display the following intermittent, clinical signs: weakness, lethargy, exercise intolerance, poor performance, muscle cramps, anaemia, jaundice and dark-coloured urine. Dark-coloured urine usually appears after strenuous exercise or after excessive barking, panting or heat exposure, and is caused by the destruction of the erythrocytes. Dogs with at least one clear copy of the gene will not develop the condition.
- Hip Dysplasia (BVA/KC Hip Dysplasia Scheme) - Dysplasia means abnormal development, and the degree of hip dysplasia present is indicated by a score assigned to each hip. The hip score is the sum of the points awarded for each on nine aspects of a radiograph (X-ray) of both hip joints. The minimum hip score is 0 and the maximum is 106 (53 for each hip). The lower the score the less the degree of hip dysplasia present. An average (or mean) score is calculated for all breeds scored under the scheme and advice for breeders is to use only breeding stock with scores below the breed mean score. In Spaniels the overall incidence of dysplasia is lower than some breeds. A Score of 10 or less indicates a sound and healthy dog. A 15 year breed average for English Springer Spaniels (1999-2014), shows a Median score of 10 (Range of 0 - 92).
- Elbow Dysplasia (BVA/KC Elbow Dysplasia Scheme) - As described above, points of the elbow joint are evaluated from radiographs of each elbow and scored from 0 to 3 with 0 being ideal.
- Eye Examination (BVA/KC/ISDS Eye Scheme) - The BVA/KC/International Sheep Dog Society (ISDS) Eye Scheme offers eye testing to screen for inherited eye disease. The aim of screening breeding stock, is so breeders can eliminate or reduce the frequency of eye disease being passed on to puppies. Under the scheme a specialist canine ophthalmologists examines a dog to look for clinical signs of inherited disease known to affect the breed in question. If no clinical signs are noted for these diseases, then the dog is declared ‘Unaffected’. If signs consistent with one or more conditions are detected, then the dog will be declared ‘Affected’ for the relevant disease. In English Springer Spaniels, conditions examined for includes Goniodysgenesis/Primary Glaucoma, Central Progressive Retinal Atrophy, Generalized Progressive Retinal Atrophy, and Multifocal Retinal Dysplasia. It is recommended that eyes are examined within 12 months of breeding (except for glaucoma predisposition which is only done once by gonioscopy), with the advice given to only breed from dogs that are found to be unaffected (or clear) of all known conditions in the breed.