Genetic Diseases
Acral Mutilation Syndrome (SPANIEL & POINTER TYPE)
Abbreviated as AMS this condition is somewhat rare and results in the dog slowly but progressively over-grooming (licking) or biting their pads and paws leading to bleeding and ulceration. This leads to bacterial and fungal infections and in many cases ulcers. Symptoms can be managed by using 'elizabeth' cones or anti-anxiety medication. if the disorder cannot be managed then euthanasia is common. It is neurological seen in a mutation of the GDNF gene affecting the development of the axon in the dog's neurons, this leads to a decrease in the sensation to recognise pain and temperature sensation.
Moderate-Severe. This is a disease with significant welfare impact on the affected animal, in terms of clinical signs and generally reduced life expectancy.
Black Hair Follicular Dysplasia
Black hair follicular dysplasia (BHFD) is inherited as an autosomal recessive trait and is a type of alopecia (hair loss) that only affects areas of black fur. It is seen in bicolour and tricolour dogs. Pups are born normally, but may show a dulling of the normal dark, glossy black hair. The hair on adjacent white skin grows normally. With time black hairs become brittle and break easily. Black hair fails to grow, and skin can become scaly. It is thought that BHFD may be related to the condition “colour dilution alopecia”, in which hair loss is seen in colour dilute animals (e.g. blue and fawn dogs). Both conditions seem to involve defects in the processing and transport of the skin and hair pigment melanin. With BHFD, the hair follicles in areas of black hair are abnormal, with clumps of melanin, distorted follicles and hyperkeratosis seen on histopathology. These abnormal hair follicles are prone to infection, and so affected areas of skin can develop bacterial folliculitis, an infection that is very irritating and can sometimes lead to deeper skin infection (pyoderma). Treatment is symptomatic only, and abnormal or missing hairs will not be replaced by normal hairs. Topical antiseptics or antibiotics are used for bacterial folliculitis. Antiseborrhoeic shampoos and oil rinses are often helpful, and general skin treatments such as omega fatty acids are often given. Other treatments recently reported of possible benefit include melatonin, etretinate (a synthetic aromatic retinoid) and niacinamide. Affected animals should not be used for breeding. Several breeds now have a DNA test available to them for screening prior to breeding.
It is a trait and so is tested based on preference, not usually for health concerns.
Autosomal Hereditary Recessive Nephropathy
Autosomal Hereditary Recessive Nephropathy (Familial Nephropathy) is an inherited disorder of the kidneys. Symptoms of chronic kidney disease usually start showing between 6 months and 2 years of age. These include excessive thirst and urination, weight loss, fatigue, vomiting, and loss of appetite. Protein is generally not present in urine, however in there is a defect in affected dogs that filters protein from the blood to the kidneys and subsequently lost in the urine. Abnormal amounts of protein can be detected in the urine as early as five months of age. Affected dogs eventually die of chronic kidney failure within a year.
Moderate-Severe. This is a disease with significant welfare impact on the affected animal, in terms of clinical signs and generally reduced life expectancy.
Progressive Rod Cone Degeneration (prcd) - PRA
Progressive retinal atrophy (PRA) is a collection of inherited diseases affecting the retina that cause blindness. Each breed exhibits a specific age of onset and pattern of inheritance, and the actual mechanism by which the retina loses function can vary. The result of almost all types of PRA is similar - generally an initial night blindness, with a slow deterioration of vision until the dog is completely blind. The age at which the dog becomes fully blind also varies, depending on the genetic disruption present and the breed. Affected eyes are not painful, unless complicated by a secondary problem, such as cataract or uveitis (inflammation due to a leaking cataract). Progressive retinal atrophy (PRA) has been classified in several different ways. The simplest of these is by age of onset. Early onset PRA occurs when the affected dog is night blind from birth, and generally is completely blind between 1 - 5 years of age. Late onset PRA is where the dog is night blind at some time over 1 year of age, and full blindness will occur at a somewhat later stage in life. Another is by the type of genetic abnormality causing the PRA. PRA may be inherited by recessive, dominant or sex-linked mechanisms in dogs. For many types of PRA in many breeds a DNA test is now available to allow for easy screening for the disease. Despite the complexity of the disease and its many forms, ultimately all forms have one thing in common – degeneration of the retina causing progressive loss of vision. DNA tests are not yet available for all affected breeds. And because breeds may also be prone to several forms of PRA (and not all may have a genetic test available) examination of the retina by a veterinary ophthalmologist remains a mainstay of the diagnostic testing regimen. In some breeds with a late onset PRA, serial eye examinations may be required before the signs of retinal degeneration become apparent. Electroretinography (ERG) is a diagnostic test that the veterinary ophthalmologist may choose to use in some cases and is a very sensitive method of detecting loss of photoreceptor function. The ERG can be a very good screening test for puppies that may have an early onset form of PRA. In progressive rod cone degeneration (known as prcd-PRA) photoreceptors of the retina appear to develop normally, then develop irregularities and progressively lose function. A mutation has been discovered on a gene called PRCD, and this mutation seems to be responsible for this condition in at least 18 breeds, when a dog possesses two copies of the mutation. This is therefore an autosomal recessive mutation, and a DNA test is available. The age of onset of retinal changes varies depending on the breed. Clinical signs may be seen from as early as 2 years of age in the golden retriever or may not be clinically apparent until 3-5 years of age, as in miniature and toy poodles. (Hence it is a late onset form of PRA.) Some cocker spaniels are even older than this when clinical signs are first seen. Initially the disease will manifest as night blindness, but will slowly progress to blindness in bright light. Serial eye exams are required to detect the early signs of PRA. Often cataracts can develop concurrently, and this may lead to uveitis or glaucoma, which can certainly be painful and needs to be treated appropriately. Dogs generally adapt quite well to blindness - especially when it develops gradually - as long as their surroundings remain familiar (e.g. furniture does not get rearranged, they do not move house etc). They should always be kept on a lead outside the yard, and care should be taken not to startle them. Balls containing bells (as an example) can be used as toys for mental stimulation.
Low-Moderate. This disease can cause some discomfort and/or dysfunction in the affected animal. It does not generally affect life expectancy.
Phosphofructokinase Deficiency (Spaniel Type)
Phosphofructokinase (PFK) is an important enzyme that is found in cells of the body and is involved in the use and regulation of glucose as an energy source. A deficiency of the PFK enzyme in cells interferes with the metabolism of glucose, and the main signs seen in affected dogs relates to the muscles and the blood cells. PFK deficiency is an autosomal recessively inherited defect, and is often present by 2 – 3 months of age. However diagnosis is often delayed, as owners may not notice the more subtle changes, and sometimes affected dogs may go for several years before being diagnosed. PFK deficiency leads to muscles that fatigue very easily, because they cannot use energy very efficiently. This manifests as muscle weakness, an inability to exercise properly, or muscle cramping. Also the muscle breakdown product myoglobin can be excreted in the urine, causing a brown discolouration of the urine. This myoglobin can also cause kidney damage or acute renal failure in large amounts. PFK activity in red blood cells is also reduced, leading to an abnormally short lifespan of these cells. This causes a (usually mild) haemolytic anaemia, and often a reticulocytosis can be detected on routine blood screening. Occasionally dogs may present with an acute severe haemolytic crisis, where a large number of red blood cells have been broken down at the same time, causing severe anaemia with shortness of breath, lethargy, weakness, fever and pale gums. Sometimes jaundice may be seen as well (yellowing of the sclera of the eyes and gums). There is no cure for PFK deficiency, and treatment is supportive only. Affected animals should avoid exercising, which can lead to muscle damage and pain, and the kidneys should be protected from muscle breakdown products (with iv fluids) to protect them from damage if necessary (e.g. after an episode of running/exercise). Occasionally blood transfusions may be required for severe anaemia. General therapy with L-carnitine, riboflavin and coenzyme Q10 has been reported to have some beneficial effects. Dogs may have a relatively normal lifespan if they avoid situations of stress and/or exercise. After 3 months of age the activity of PFK can be tested in the red blood cells, and there is also a DNA test available for several breeds (the English springer spaniel, the American and English cocker spaniel, the Wachtelhund and the whippet), which allows for accurate screening of breeding stock. This disease has also been reported in mixed breed dogs.
Low-Moderate. This disease can cause some discomfort and/or dysfunction in the affected animal. It does not generally affect life expectancy.
Exercise Induced Collapse (Retriever Type)
This is an autosomal recessive condition that affects Labradors, as well as several other related breeds. The condition is also seen in mixed breeds, mainly Labrador crosses. The condition is not common, although it is estimated up to 35% of the Labrador population (in the USA) may be carriers of the gene mutation that causes the disease (ie mutation of the dynamin-1 gene). Signs are usually first seen in young adults, between 6 months and 3 years of age. With vigorous exercise lasting 5-20 minutes, a loss of control becomes apparent in the hind limbs. Starting as a wobbly gait, the loss of control progresses to collapse, and sometimes dogs may seem confused. Occasional deaths have been reported, so it is important that exercise is stopped as soon as signs first appear. Excitement and high temperatures and/or humidity may exacerbate signs. There are sporadic reports of various supplements having some positive effect in a small number of dogs, as well as one report of sub-anticonvulsant doses of phenobarbitone being useful in some severely affected dogs; however there is currently no proven reliable cure or treatment for this disease. All affected animals should be withdrawn from work and should avoid situations involving excitement and/or stress.
Low-Moderate. This disease can cause some discomfort and/or dysfunction in the affected animal. It does not generally affect life expectancy.
Bernard-Soulier Syndrome (Cocker Spaniel Type)
Moderate. This disease can cause significant signs of discomfort and/or dysfunction in affected animals. It may involve relatively high treatment/management costs, and can sometimes reduce life expectancy.