Biology Reference
In-Depth Information
the western hognose snake,
H. nasicus
; Weinstein and Keyler, 2009; Plate 4.24D-J;
Table 4.1
), a hematoma appeared along the arm between the elbow and the axilla, as
well as at the bite site (Ineich et al., 2006). The patient was observed in an emergency
room for 12 h and treated with an i.v. antihistamine. There were no laboratory results
included in this report, and no other symptoms or signs were mentioned. There were
no signs of neurotoxicity, and no significant bleeding was reported (Ineich et al., 2006).
The patient's edema persisted for 5-6 days; mild residual pain in the affected thumb
remained for several additional days. The hematoma on the arm remained visible for
almost 1 week, and slowly diminishing pain in the “arm lymphatic tract” was reported
(Ineich et al., 2006). Some of these effects could be interpreted as lymphatic spread of
introduced Duvernoy's secretion, or lymphatic drainage related to regional hypersensi-
tivity (see Section 4.6).
As with
B. dendrophila
, anecdotal reports posted on the Internet (Appendix A)
describe prolonged bleeding and/or edema following protracted bites from captive
specimens of
Thrasops jacksoni
(western black tree snake, Jackson's black tree snake
or isilukanga; there are other names as well). However, as these were not formally
medically reviewed, risk assessment and clinical evaluation of this taxon are not fea-
sible using the information in these cases of unconfirmed provenance (see later and
Section 4.5). Similarly, there are no data available about possible risks by bites of the
third species,
T. occidentalis
(also often referred to as the western black tree snake).
Although some authors are eager to ascribe perceived significant risk to some
ophidian species of little-known importance (i.e.,
Boiga
(
Toxicodryas
)
blandingi
),
others have underestimated the lethal potential of some of the Dispholidini. Sweeney
(1971) stated that bites from
Thelotornis
spp. caused edema, pain, and fever, but did
not cause “true hemophilia.” Although the lethal potential of
D. typus
was clearly
identified as early as 1909 (FitzSimons, 1909), Cansdale (1955) questioned the docu-
mented hazard posed by
D. typus
and opined that
Thelotornis
spp. was “almost harm-
less.” These mixed and incorrect popular perceptions of the danger of these snakes
may have contributed to the deaths of Robert Mertens, Karl Schmidt, and probably
others as well.
Envenomation by these snakes often features severe consumptive coagulopathy
with disseminated intravascular coagulation (DIC) causing spontaneous systemic
bleeding that can pose a clinical management challenge for the attending physician.
In cases of
D. typus
envenomation, symptoms may appear very soon after the bite or
be delayed for 12-48 h, resulting in premature discharge from the hospital (Lakier
and Fritz, 1969; Nicolson et al., 1974; Reitz, 1989). Persistent bleeding from the
“fang” or maxillary teeth puncture marks is often the first symptom. Dizziness, syn-
cope, shock, and seizures within the first 15 min after the bite have been described.
Within a few hours, nausea, vomiting, colicky abdominal pain and severe, often
occipital, headache may develop (Broadley, 1960). There may be bleeding from
old and recent wounds such as venepunctures and scratches, as well as spontane-
ous systemic bleeding from gums, nose, conjunctivae, and external auditory meatus.
Numerous documented cases have included: hematemesis, hemoptysis, rectal bleed-
ing, hematochezia or melena, subarachnoid and intracranial hemorrhages, hematuria,
