The technique is based on a pituitary-ovarian endocrine challenge test using the synthetic gonadotrophin releasing hormone buserelin (Receptal; Hoechst). This is available in 10ml vials containing 0.004 mg/ml (4 m g/ml) buserelin. Dilution 1/10 with water for injection may make the volumes more manageable.

PROTOCOL

1. Take a basal sample of 2ml clotted blood.
1. Inject i/v 0.32 m g buserelin for a bitch with a body weight of 12 - 15 kg.
1. 1 to 1.5 hours later take a second sample of 2ml clotted blood.
1. Separate the sera before despatching to the laboratory.

Normal bitches or those with residual ovarian tissue:
 

Oestradiol	Pre-injection	<18 pmol/L (assuming anoestrus)
	Post-injection	55 - 74 pmol/L

Pre-injection oestradiol levels >100 pmol/L would be indicative of proestrus/oestrus and would confirm the presence of active ovarian tissue.
 

Test Code	Test Name and Description	Sample
OVA	Ovarian Activity (Canine)	2 x serum

REFERENCE

Jeffcoate, I.A (1991). Identification of Spayed Bitches (Correspondence). Veterinary Record 129 p 58.