Tag archives: dwarfism

Preventing Congenital Hypothyroidism with Goiter in the Toy Fox Terrier

Preventing Congenital Hypothyroidism with Goiter in the Toy Fox Terrier

With a personality much bigger than their diminutive size, the toy fox terrier (TFT) is a fun and feisty breed well known for their charming and entertaining personalities. Originally created by the breeding of various toy breeds to the smooth fox terrier, like other terriers, TFTs still love the thrill of the hunt and are at their happiest giving chase to any small mammal willing to run. Though toy fox terriers have occasionally been described as headstrong and have been known to take control of a house, a well socialized and well trained toy fox terrier is a wonderful addition to many families. Still retaining tenacity from their terrier roots, their disposition is also tailored by the variety of toy breeds used to make this fine breed. Unfortunately, like other purebred dogs, the TFT has developed some inherited disease concerns along their path to the modern breed. Luckily, some of these diseases can now be prevented by performing genetic testing on dams and sires prior to breeding and by implementing selective breeding strategies based upon these results. One such genetic condition known to occur in TFTs is congenital hypothyroidism with goiter (CHG), a disease caused by a genetic mutation in ...

Skeletal Dysplasia 2 and Retinal Dysplasia/Oculoskeletal Dysplasia 1 in the Labrador retriever

Skeletal Dysplasia 2 and Retinal Dysplasia/Oculoskeletal Dysplasia 1 in the Labrador retriever

In this second part of a four part blog series examining preventable inherited diseases of the Labrador retriever (see part one here) we will be examining two diseases known to cause dwarfism in the breed.

Skeletal Dysplasia 2

Skeletal dysplasia 2 (SD2) is an inherited disease of collagen resulting in disproportionate dwarfism in the Labrador. Disproportionate dwarfism is marked by abnormal size discrepancies between the limb length of affected individuals and the size of their torso. In the case of SD2, the limbs of affected dogs tend to be shorter than normal despite an average sized torso. International breed standards of the Labrador list shoulder heights of 56-57 cm in males and 54-56 cm in females. In the publication describing the COL11A2 gene mutation associated with SD2, the authors found that most of the affected males had shoulder heights of less than 55 cm and most affected females showed heights of less than 50 cm. However, there is some overlap of shoulder heights between those of normal dogs from blood lines of smaller size and affected dogs from larger sized blood lines. Though the front limbs tend to be more severely affected (and sometimes slightly bowed) with SD2, the long ...

Skeletal Dysplasia 2: A cause of dwarfism in the Labrador retriever

Skeletal Dysplasia 2: A cause of dwarfism in the Labrador retriever

Thanks to human selection and breeding, the physical appearance of dogs varies tremendously. Using only physical attributes as a guide, it’s safe to say that most uninformed biologists would have a hard time believing that a Chihuahua and a great dane were from the same species, let alone that they were capable of producing viable offspring together. In order to facilitate such dynamic intraspecies diversity of canines, people have long used random genetic mutations to their advantage. One example is the selection for various forms of dwarfism. Breeds such as the dachshund, corgi and the Basset hound have been created through selective breeding of individuals with a genetic mutation of the FGF4 gene that when inherited from one of their parents, leads to the characteristic short legs of these breeds. While a mutation for dwarfism is an expected standard for some breeds, it can be particularly undesirable in others.

A prime example of an undesirable mutation (especially for working dogs) is a mutation in the COL11A2 gene that causes a generally mild disproportionate dwarfism in the Labrador retriever known as skeletal dysplasia 2 (SD2). Disproportionate dwarfism is characterized by one or more body parts being smaller in comparison to overall ...