Distal Fractures of the Radius and Ulna (Broken front leg)
Related terms: antibrachial fracture, fracture non-union, fracture malunion, fracture delayed union.
Outline: Pomeranians, like dogs of other miniature and toy breeds, have a high prevalence of fractures of the distal radius and ulna, that is, of the lower part of the forearm. Not only do they occur more commonly in Pomeranians than in larger dogs, but they also often take a long time to heal or even fail to do so. These fractures can occur as a result of relatively minor trauma and it has been found that the bones are relatively weaker, in relation to body size, than in larger dogs. These fractures cause acute and severe pain and their pain and discomfort can be of days to months in duration depending on how well they heal. Whether predisposition to these fractures is an unavoidable by-product of selecting for small size or whether selecting for stronger bones (by not breeding from dogs that have had fractures) might prove successful in tackling the problem, is not known. As far as we are aware there are no coordinated efforts to address the issue.
Brief description
All toy breed dogs, including the Pomeranian are vulnerable to fractures of the distal (lower end of the) radius and ulna (Denny 1985, Muir 1997). Generally, these types of fracture are the result of major trauma, such as road traffic accidents, but in toy breeds they can commonly result from only rather minor trauma (Waters et al 1993, Muir 1997, Rochat 2010). The commonest cause appears to be jumping or falling from a height eg from the owner’s arms (Sumner-Smith 1974a, Harasen 2003a, Rochat 2010, McCartney et al 2010). These fractures occur because, in relation to their body weight, of the lower mechanical strength of the distal radius and ulna in toy breeds compared to other breeds. This is due to size-related differences in the cross-sectional structure of the bones (Brianza et al 2006).
Delayed (non-union) healing of this type of fracture is also more common in toy than in larger breeds of dogs (Vaughan 1964, Sumner-Smith & Cawley 1970, Sumner-Smith 1974a, b, Muir 1997, Harasen 2003a, Welch et al 1997, McCartney et al 2010). Factors associated with delayed or incomplete healing of these fractures include: reduced blood supply to the distal radius in toy breeds; the absence of soft tissues enveloping the fracture site in these breeds; and the ‘exuberant’ nature of these dogs resulting in their wanting to use the limb soon after surgery or before external stabilisation of the fracture.
Casts and splints are generally no longer used to treat distal radial fractures in toy breeds, as the number of cases in which the break fails to heal can be as high as 80% (Muir 1997, Welshet al 1997; Harasen 2003b). Surgical interventions that rigidly fix the bones are necessary to allow these fractures to heal.
Intensity of welfare impact
Fractures of long bones are extremely painful, from the time of fracture until appropriate veterinary intervention. Treatment is likely to involve travel to a veterinary practice, surgery, and subsequent medication and all these may cause significant stress to the affected animal. During healing, pain and discomfort may occur and restriction of normal activities is likely.
Some dogs with fracture that fail to heal may have to undergo repeated surgical interventions and, occasionally, amputation of the limb is necessary (Hunt et al 1980, Muir 1997).
Duration of welfare impact
It can take months for these fractures to heal. If the broken ends fail to unite (non-union), the healing process can be protracted and may last many months.
Number of animals affected
Denny (1985) suggested that fractures of the distal antebrachium (the lower part of the front leg between the elbow and wrist), in dogs weighing less than 3 kg, are relatively common. However, we are unaware of any published data on the prevalence of these fractures in Pomeranians.
Diagnosis
A fracture will be suspected in any Pomeranian showing signs of acute forelimb lameness, especially if there is swelling or deformity, and particularly after a fall or a jump. The diagnosis can be confirmed, and the site and nature of the fracture determined, by radiography (x-rays).
Genetics
Many miniature or toy dog breeds, including Pomeranians, are apparently predisposed to distal fractures of the radius and ulna and to subsequent non-union (failure to heal) of these fractures. A single gene for an insulin-like growth factor (IGF1) has been identified that influences variation in body size between many breeds of dog. One form of this gene is associated with small body size, another with larger size (Sutter et al 2007). However, other genes may also be involved in determining body size among breeds of dogs.
How do you know if an animal is a carrier or likely to become affected?
All Pomeranians are vulnerable to radial and ulna fractures that are the result of relatively mild trauma and all are at risk of the delayed healing of these fractures.
Methods and prospects for elimination of the problem
The relatively high risk of these antebrachial fractures, that tend to heal poorly in toy breeds, appears to be associated with small body size. It may be that reducing their prevalence will therefore be difficult without also selecting for an increase in body size.
Related terms: antibrachial fracture, fracture non-union, fracture malunion, fracture delayed union.
Outline: Pomeranians, like dogs of other miniature and toy breeds, have a high prevalence of fractures of the distal radius and ulna, that is, of the lower part of the forearm. Not only do they occur more commonly in Pomeranians than in larger dogs, but they also often take a long time to heal or even fail to do so. These fractures can occur as a result of relatively minor trauma and it has been found that the bones are relatively weaker, in relation to body size, than in larger dogs. These fractures cause acute and severe pain and their pain and discomfort can be of days to months in duration depending on how well they heal. Whether predisposition to these fractures is an unavoidable by-product of selecting for small size or whether selecting for stronger bones (by not breeding from dogs that have had fractures) might prove successful in tackling the problem, is not known. As far as we are aware there are no coordinated efforts to address the issue.
Brief description
All toy breed dogs, including the Pomeranian are vulnerable to fractures of the distal (lower end of the) radius and ulna (Denny 1985, Muir 1997). Generally, these types of fracture are the result of major trauma, such as road traffic accidents, but in toy breeds they can commonly result from only rather minor trauma (Waters et al 1993, Muir 1997, Rochat 2010). The commonest cause appears to be jumping or falling from a height eg from the owner’s arms (Sumner-Smith 1974a, Harasen 2003a, Rochat 2010, McCartney et al 2010). These fractures occur because, in relation to their body weight, of the lower mechanical strength of the distal radius and ulna in toy breeds compared to other breeds. This is due to size-related differences in the cross-sectional structure of the bones (Brianza et al 2006).
Delayed (non-union) healing of this type of fracture is also more common in toy than in larger breeds of dogs (Vaughan 1964, Sumner-Smith & Cawley 1970, Sumner-Smith 1974a, b, Muir 1997, Harasen 2003a, Welch et al 1997, McCartney et al 2010). Factors associated with delayed or incomplete healing of these fractures include: reduced blood supply to the distal radius in toy breeds; the absence of soft tissues enveloping the fracture site in these breeds; and the ‘exuberant’ nature of these dogs resulting in their wanting to use the limb soon after surgery or before external stabilisation of the fracture.
Casts and splints are generally no longer used to treat distal radial fractures in toy breeds, as the number of cases in which the break fails to heal can be as high as 80% (Muir 1997, Welshet al 1997; Harasen 2003b). Surgical interventions that rigidly fix the bones are necessary to allow these fractures to heal.
Intensity of welfare impact
Fractures of long bones are extremely painful, from the time of fracture until appropriate veterinary intervention. Treatment is likely to involve travel to a veterinary practice, surgery, and subsequent medication and all these may cause significant stress to the affected animal. During healing, pain and discomfort may occur and restriction of normal activities is likely.
Some dogs with fracture that fail to heal may have to undergo repeated surgical interventions and, occasionally, amputation of the limb is necessary (Hunt et al 1980, Muir 1997).
Duration of welfare impact
It can take months for these fractures to heal. If the broken ends fail to unite (non-union), the healing process can be protracted and may last many months.
Number of animals affected
Denny (1985) suggested that fractures of the distal antebrachium (the lower part of the front leg between the elbow and wrist), in dogs weighing less than 3 kg, are relatively common. However, we are unaware of any published data on the prevalence of these fractures in Pomeranians.
Diagnosis
A fracture will be suspected in any Pomeranian showing signs of acute forelimb lameness, especially if there is swelling or deformity, and particularly after a fall or a jump. The diagnosis can be confirmed, and the site and nature of the fracture determined, by radiography (x-rays).
Genetics
Many miniature or toy dog breeds, including Pomeranians, are apparently predisposed to distal fractures of the radius and ulna and to subsequent non-union (failure to heal) of these fractures. A single gene for an insulin-like growth factor (IGF1) has been identified that influences variation in body size between many breeds of dog. One form of this gene is associated with small body size, another with larger size (Sutter et al 2007). However, other genes may also be involved in determining body size among breeds of dogs.
How do you know if an animal is a carrier or likely to become affected?
All Pomeranians are vulnerable to radial and ulna fractures that are the result of relatively mild trauma and all are at risk of the delayed healing of these fractures.
Methods and prospects for elimination of the problem
The relatively high risk of these antebrachial fractures, that tend to heal poorly in toy breeds, appears to be associated with small body size. It may be that reducing their prevalence will therefore be difficult without also selecting for an increase in body size.
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No photo's or text maybe copied from this site.
Copyright to The Pomeranian Club 2021.