Snofalls and Brian,
I think you guys have identified an important varient subtype of tractorphilia in which the particular brand obsession complicates both diagnosis and management. As you have noted, the "Deere" group may have higher rates of misdiagnosis leading to injuries inflicted by spouses. Similarly, the ASPCA may become involved before mental health professionals in certain cases when patients mutter about coyotes in the garage or hooking up attachments to coyotes to work on a farm.
Other new varients are being decribed as well. One particularly common type may have unusual reactions to seeing colored objects especially while driving. I believe DodgeRam may have this subtype. What is absolutely fascinating is that while all members of this group rubberneck while driving, the stimulus is not consistent. Individual patients respond to DIFFERENT colors. It is reported that there are patients who turn only to observe orange objects while other patients respond similarly only to red, blue or green objects. In addition to the sudden turning of the head, these patients also lose track of conversations during these color induced seizures. Spousal reports are the most accurate means of identifying patients with this varient illness as the patients rarely report the problem themselves.
I must say that it feels as though we are discovering more and more about this complicated illness every day. Freud must have experienced similar excitement as he started to unravel the psyche. I wonder, by the way, what color tractor he would have owned?