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4.7 Medical Conditions That Have Breed Tendencies and Their Associated Behavior Changes
ОглавлениеDiseases that have a breed tendency can be due to morphologic extremes or to an inherited condition (Rooney 2009). Examples of morphologic extremes include characteristics like dome‐shaped heads in Cavalier King Charles spaniels and corkscrew tails in bulldogs. Inherited conditions are numerous, and, at last count, 312 non‐conformation‐linked inherited disorders had been identified in the top 50 breeds of registered dogs (Summers et al. 2010).
Selecting for breed standards and specific characteristics leads to inbreeding, reducing variation and causing an increased likelihood of concentrating genes that may have undesired effects. In addition, the incidence of these diseases in mixed‐breed and shelter dog populations has never been studied and is, therefore, unknown.
Recent research has attempted to divide diseases with breed tendencies into (i) disorders related to breed standards and (ii) inherited defects (Asher et al. 2009; Summers et al. 2010). In addition, a Genetic Illness Severity Index for Dogs (GISID) was developed to rank these conditions in terms of their impact on the welfare of the dog (Asher et al. 2009). In general, these diseases affect welfare by compromising a particular body system, often causing pain and discomfort (Yeates 2012). In addition, some of these conditions may further impact welfare by preventing normal expressions of behavior, either due to pain or associated with anatomical alterations such as ear, tail, and body conformation (Rooney 2009).
Although the cat genome has been mapped, not as much progress has been made in identifying genetic diseases in cats. Purebred cats make up only a small portion of the overall cat population (estimates show that about 8% of cats are purebred) (American Pet Products Association 2013). Compared to the multitude of genetic tests available for dogs, there are only 20 that have been developed for cats (Slutsky et al. 2013).
A database developed by the University of Pennsylvania allows users to search for available genetic tests in both cats and dogs (Slutsky et al. 2013):
