I found a great list of potential reading.

Hill, R. E. and S. P. Mackessy. 2000. Characterization of venom (Duvernoy's secretion) from twelve species of colubrid snakes and partial sequence of four venom proteins. Toxicon 38(12):1663-1687. Report enzyme assays, electrophoresis, protein sequencing, etc. for venom, saliva New, Old World species; observe Thamnophis, Diadophis, Hypsiglena bites lethal to other snakes.

Rossi, J. V. and R. Rossi. 1995. Snakes of the United States and Canada, Vol. 2. Western Area. Krieger Publishing Company, Malabar, FL, 325 pp. Mention "venom" effects - Coniophanes, Heterodon, Hypsiglena, Leptodeira, Oxybelis, Tantilla, Thamnophis, Trimorphodon.

Gomez, H. F., M. Davis, S. Phillips, P. McKinney, and J. Brent. 1994. Human envenomation from a wandering garter snake. Annals of Emergency Medicine 23(5):1119-1122. Report local edema, ecchymosis, hemorrhagic vesicles after prolonged bite, no systemic effects; describe hospital treatment; include photos.

Weed, H. G. 1993. Nonvenomous snakebite in Massachusetts: prophylactic antibiotics are unnecessary. Annals of Emergency Medicine 22(2):220-224. Reports Thamnophis (47 cases), Storeria (3), Elaphe (2), Nerodia (1), Lampropeltis (1): "wounds...pinpoint abrasions...no erythema, edema, blistering, or lymphangitic streaking," no prolonged bleeding.

Ernst, C. H. and R. W. Barbour. 1989. Snakes of Eastern North America. George Mason University Press, Fairfax, VA, 282 pp. Comment on toxicity, or questioned toxicity, Farancia, Heterodon, Rhadinaea, Tantilla, Nerodia, Thamnophis; note senior author developed allergy to saliva T. sirtalis - "burning rash at the site."

Jansen, D. W. 1987. The myonecrotic effect of Duvernoy's gland secretion of the snake Thamnophis elegans vagrans. Journal of Herpetology 21(1):81-83. Reports rhabdomyodegeneration, necrosis, hemorrhagic damage, etc. in mice following intramuscular injection; relates findings to speculation evolution venoms

Nichols, A. 1986. Envenomation by a bluestripe garter snake, Thamnophis sirtalis similis. Herpetological Review 17(1):6. Reports localized edema, cyanosis, arthralgia, numbness, lymphadenitis axillary nodes from prolonged bite; discounts allergy, infection as factors.

Hayes, W. K. and F. E. Hayes. 1985. Human envenomation from the bite of the eastern garter snake, Thamnophis s. sirtalis (Serpentes: Colubridae). Toxicon 23(4):719-721. Report FEH hospitalized after prolonged bite Delaware - localized edema, ecchymosis, lymphadenitis, etc.; vital signs, lab tests normal; allergy, infection not implicated.

Rosenberg, H. I., A. Bdolah, and E. Kochva. 1985. Lethal factors and enzymes in the secretion from Duvernoy's gland of three colubrid snakes. The Journal of Experimental Zoology 233(1):5-14. Report Malpolon, Spalerosophis far more toxic than Thamnophis; describe use pilocarpine in collection secretions; provide detailed discussion, literature review.

Jansen, D. W. and R. C. Foehring. 1983. The mechanism of venom secretion from Duvernoy's gland of the snake Thamnophis sirtalis. Journal of Morphology 175(3):271-277. Report adductor musculature not directly connected to Duvernoy's gland however find stimulation this musculature increases secretion release.

Phelps, T. 1981. Poisonous Snakes. Blandford Press Ltd. Poole, Dorset, 237 pp. Discusses variety rear-fanged colubrids; notes saliva some non-venomous species, e.g. Natrix, Thamnophis, "said to have a paralyzing effect on prey."

Vest, D. K. 1981. Envenomation following the bite of a wandering garter snake (Thamnophis elegans vagrans). Clinical Toxicology 18(5):573-579. Reports prolonged bite, child - localized bleeding, swelling (rapid onset), edema, pain, ecchymosis (includes drawing, photo of signs).

Vest, D. K. 1981. The toxic Duvernoy's secretion of the wandering garter snake, Thamnophis elegans vagrans. Toxicon 19(6):831-839. Reports i.p. LD 50 mice 13.85 mg/kg, "massive pulmonary hemorrhage," etc. observed; other oral secretions no significant effects; describes micro-aspiration technique collection secretion.

Wright, D.L., K.V. Kardong, and D.L. Bentley. 1979. The functional anatomy of the teeth of the western terrestrial garter snake, Thamnophis elegans. Herpetologica 35(3):223-228. Report rear maxillary teeth enlarged, have cutting edge; speculate may facilitate flow (possibly toxic) saliva into prey.