Improving the enforcement of Finnish animal welfare legislation related to animal breeding. Part III: Problems and control criteria in dog breeding

This report defines control criteria and thresholds (breeding restrictions) under Finnish animal welfare legislation for genetic diseases in dogs that negatively affect their well-being. It addresses diseases and issues that were not included in the initial 2020 report, or for which further clarification was deemed necessary for the development of control criteria. According to the proposed control criteria and thresholds, breeding dogs must not have serious genetic diseases or traits that could lead to significant welfare issues. The prevalence of hereditary diseases increases in consanguineous animal populations as genetic variation decreases. This results in increased morbidity throughout a dog's life and a significantly reduced lifespan. It also causes reproductive problems, puppy mortality, malformations in puppies, reduced immunity, and increased susceptibility to inflammation. The report therefore calls for genetic variation to be maintained and increased in breeding populations and suggests that puppies should not be bred from close relatives. Intense fear can severely restrict dogs' and their owners' lives, causing significant welfare issues. Severe fear is a stressful condition that puts the whole body on alert. Long-term exposure to this state increases the risk of illness and obsessive-compulsive behaviour. Fear is also a common cause of bite incidents. Since genes largely regulate fearfulness and aggression, dogs that can cope with an active daily life without displaying excessive fear or aggression should be used for breeding. Atopic dermatitis is a highly hereditary inflammatory skin disease that causes significant itchiness. If left untreated, it can lead to serious welfare issues for dogs. In humans, prolonged itching is considered a serious symptom, and the perceived discomfort is comparable to prolonged pain. Unfortunately, however, dog owners often fail to recognise the serious welfare issues that atopy causes their dogs. Atopy also places a burden on owners, as it requires lifelong treatment that is time-consuming and can place psychological and financial strain on them. This can negatively affect owners' commitment to managing the condition. However, effective treatment can eliminate symptoms, though it does not eliminate the risk of passing the disease on to offspring. Overall, the risk of offspring developing atopy can be reduced by ensuring that breeding dogs have healthy skin. Atopy is the main cause of pododermatitis in dogs. This multifactorial disease is also influenced by the dog's conformation. Chronic and progressive skin inflammation resulting from an abnormal position or shape of the paws can significantly reduce quality of life and is a debilitating condition. Heart disease is a significant cause of morbidity and mortality in dogs worldwide. Welfare damage is usually due to congestive heart failure. In this condition, the heart is unable to maintain normal blood flow, resulting in a reduced oxygen supply to the body and fluid build-up in the tissues. Heart failure progresses gradually and can eventually lead to death. Some heart diseases can also cause sudden death in young dogs. The most common heart conditions in dogs are chronic and incurable. To reduce the incidence of heart disease, breeding programmes for many breeds require heart examinations to identify suitable breeding stock. Many dental problems are related to the structure of the skull and jaw. Despite being painful, dental defects and diseases can often go unnoticed by dog owners. For example, they can destroy the jawbone and even cause it to fracture. Dog breeding programmes should prioritise conformation and structure that reduce the risk of serious oral and dental problems, ensuring that dogs have healthy teeth and a functioning bite. With regard to musculoskeletal disorders, this report builds on the previous one by considering the following conditions: chondrodystrophy, intervertebral disc disease, chondrodysplasia (short limbs), patellar luxation, cranial cruciate ligament disease, and osteochondrosis. Chondrodystrophic dogs are those whose intervertebral discs degenerate prematurely. This degeneration is caused by a retrogene located on chromosome 12 (CDDY). Degeneration of the discs makes them prone to protruding into the spinal canal or even rupturing. This can result in damage to the spinal cord and nerves, causing pain and paralysis. In the most severe cases, euthanasia is necessary. Dogs susceptible to herniated discs may experience multiple herniations in different vertebral canals throughout their lifetime. The primary objective of breeding should be to prevent the premature degeneration of intervertebral discs, as this is the primary risk factor for disc herniation and spinal cord injury. This can be achieved by reducing the frequency of the predisposing retrogene in breed populations. Another possibility is X-ray screening of breeding dogs to reduce the risk of disc herniation. A long-term breeding strategy may require a combination of genetic testing and crossbreeding. A retrogene on chromosome 18 (CDPA) causes short stature in dogs by prompting the growth plates in their limbs to close prematurely. This can result in varying degrees of rotation and bending of the limbs, as well as incongruity of the elbow joint. In cases where the limbs are very short and twisted, the misalignment can cause them to rub against the chest. The misalignment predisposes dogs to osteoarthritis, chronic pain, and pododermatitis. These joint problems and the resulting pain often become more apparent as the dog ages, and the condition worsens. When breeding, preference should be given to dogs with normal limb structure and posture. Patellar luxation, cranial cruciate ligament disease, osteochondrosis, and osteoarthritis are among the most common musculoskeletal disorders in dogs. These conditions are usually painful and often become chronic, causing welfare problems for affected dogs over a considerable period of time. Structural weaknesses in the stifle joint can lead to patellar luxation. In turn, luxation increases the risk of cranial cruciate ligament disease. Patellar luxation is relatively common in small dogs, as well as in larger breeds with straight hind legs. According to Finnish screening statistics, patellar luxation occurs in almost every second dog of certain breeds. Only dogs without patellar luxation should be used for breeding. Cranial cruciate ligament disease (rupture) is highly hereditary, although it often occurs alongside trauma. Many of the predisposing factors are also hereditary. If a dog is diagnosed with and treated for this disease, there is about a 50% chance that they will develop the same lesion in the other knee within the next year. The incidence of cranial cruciate ligament disease could be reduced through selective breeding. This could be achieved by collecting data on affected dogs and excluding them from breeding programmes while promoting healthy, functional conformation. Progress could be enhanced by risk prediction based on pedigree and/or genome data (e.g. estimated breeding values, genetic testing). With regard to eye diseases, the report supplements the breeding restrictions listed in the previous report for conditions that cause pain or discomfort, pose a threat to vision and require surgical treatment or ongoing medication. Some characteristics that define a dog's breed are caused by gene variants that also cause or predispose dogs to welfare issues. These variants are selected and maintained to preserve breed characteristics. This report addresses such gene variants, including those responsible for certain coat colours, excessive skin folds, shortened tails, and hairlessness. It shows that most genetic diseases and health problems in dogs become apparent by the age of three. Therefore, it is important to refrain from large-scale breeding of dogs under the age of three, to allow any potential genetic issues to manifest. Many diseases and defects that cause welfare problems in dogs are related to their conformation. Heritabilities for conformation traits are usually high, making it relatively easy to reduce unhealthy conformations through breeding, particularly if a large gene pool is maintained by making use of all available tools. This report proposes regular reviews and updates to the breeding restrictions. After the transition period, measures to reduce retrogenes causing chondrodystrophy and short stature in breeds should be examined. Similarly, the relationship between extremes of dog size, coat type and welfare issues should be investigated.