Do dogs (and animals in general) have mental/personality disorders? There all those books/people out there defining the overall temperment of certain breeds...when in reality they could be passing on mental illness or personality disorders through their selective breeding.
Jack Russels are super hyper: OCD
Pit Bulls are aggressive: Antisocial Personality Disorder (PD)
Shar-peis are the #1 dog to turn on their owner: Schizophrenia (hallucinations/delusions)
Chihuahuas are bark @ everything: Panarnoid PD
Golden Retreviers are man's best friend: normal :-)
Muts are sometimes the best dogs: all the dominant/recessive gene disorders never got far
Dogs that are classified as lazy: narcolepsy
Cats sometimes love you, then hate you: manic depression
Think about it.