Early spay study

This was posted on my CPDT email list.
I found it very interesting! I thought ya'll might want to see it too:

Vet J. 2006 Jul;172(1):154-9. Links
Comment in:
Vet J. 2007 Jan;173(1):9-11.
Effects of ovariohysterectomy on reactivity in German Shepherd dogs.

Kim HH, Yeon SC, Houpt KA, Lee HC, Chang HH, Lee HJ.
Institute of Animal Medicine, College of Veterinary Medicine,
Gyeongsang National University, Jinju 660-701, Republic of Korea.

This study investigated the effects of ovariohysterectomy on
reactivity of German Shepherd dogs. Fourteen healthy dogs ranging in age from 5 to 10 months were assigned to an ovariohysterectomy or a sexually intact group.

Their behaviours were digitally video recorded 4-5 months after treatment and analysed for treatment effects on reactivity.

Responses to the approach of an unfamiliar human leading an unknown dog were assigned the following reactivity scores: severe reactivity, 3; moderate reactivity, 2; defensive or mild reactivity,
1; attentive or no reactivity, 0.

Median reactivity scores in response to the approach of an unfamiliar human walking with an unknown dog were calculated for each observation period.

Dogs in the ovariohysterectomized group showed more reactivity, and median reactivity scores were higher in the ovariohysterectomy group compared with those of the sexually intact group.

Ovariohysterectomy of 5-10 month old German Shepherd bitches specifically, and perhaps bitches of any breed generally, may induce an increase in reactivity.

Practitioners may benefit from recognizing that a range of
behavioural changes may occur post-ovariohysterectomy.