Captive Rattlesnakes Research Articles

Does Rattling Deter? The Case of Domestic Dogs.

Although the rattling of rattlesnakes (Crotalus and Sistrurus) is widely accepted as being aposematic, the hypothesis that rattling deters approach from the snake's potentially dangerous adversaries has not been well tested. In a controlled study using rattling recorded from captive rattlesnakes (C. oreganus helleri) and a variety of comparison sounds or no-sound controls, domestic dogs (Canis familiaris) showed no hesitation to approach camouflaged speakers projecting the recorded rattles. The dogs were equally likely to approach speakers projecting rattling as they were to approach speakers playing control sounds, or speakers that were silent. Furthermore, the dogs spent no less time in front of the speakers projecting the rattles than they did in front of speakers projecting control sounds or no sound. The dogs' reactions may not be representative of other species with whom rattlesnakes come into contact, but the data suggest a need for some circumspection about the role of rattling in the rattlesnake's defensive repertoire. Our results also suggest that dogs may be vulnerable to envenomation because they fail to react to the sound of rattling with avoidance.

Effect of a biostimulatory homeopathic complex on venom production in captive rattlesnakes (Crotalus durissus).

The purpose of this study was to evaluate the effect of two administration methods of a biostimulatory homeopathic complex (Convert H®) on the production of fresh and lyophilized venom of rattlesnakes (Crotalus durissus) under intensive captivity conditions. Sixty snakes were subjected to treatment following a randomized block design. The effects of sex and size were controlled for. Thirteen consecutive extractions were performed over 21 months. The first factor considered in the experiment was the origin of mice used as prey: a conventional colony (A1) or the Convert H colony (A2; mice receiving the homeopathic complex in water at 1%). The type of water given to snakes was the second factor: pure (B1) or amended with 5% of Convert H® (B2). The experiment was structured in a factorial 2×2 design combining mouse and water types (A1B1, A1B2, A2B1, and A2B2). No consistent treatment effects on fresh venom production (mL) were observed when the experimental groups were compared with controls (A1B1). However, production of lyophilized venom (mg) was significantly higher (p<0.05) in A2B2 animals than in controls in eight of 13 extractions performed, and also in aggregate. The results revealed that production of lyophilized venom, measured over multiple extractions, can be increased by administering the homeopathic complex simultaneously to rattlesnakes and prey.

Microscopic agglutination test on captive rattlesnakes : Data on serovars and titers.

The microscopic agglutination test (MAT) is considered the “golden standard” leptospirosis serodiagnostic test, but there is little information about it as it pertains to snakes. To fill this information gap, we provide data on serovars and titers of fifty-six Crotalus durissus collilineatus sera samples that tested positive by MAT (10.1016/j.actatropica.2016.02.006 (Rodrigues et al., 2016) [5]). These data are presented in a table, along with a description of the methodology used for sample collection and serologic testing.

Variación estacional del contenido proteico y actividad de la PLA2 del veneno de Crotalus molossus molossus entre especímenes de origen silvestre y en cautiverio

Envenomation by rattlesnake bites is medical imperative. Medicine focuses on diverse fac­tors such as climate, age, sex, distribution, season of the year and diet, as these make the snake’s venom more poisonous and toxic. The objective of this study is to provide informa­tion on the seasonal variation of the protein content and hemolytic damage of the venom produced by captive and wild Crotalus molossus molossus. For this, we analyzed 16 samples of venom using the colorimetric method and visualized by Sodium Dodecyl Sulfate-Polyacryl­amide Gel Electrophoresis (SDS-PAGE). The hemolytic activity of the phospholipase A2 (PLA2) was evaluated on erythrocytes-agar plates.We observed a large variation in the protein con­tent between captive and wild snake venom; the winter pool of wild snake venom stands out with the highest concentration at 697 μg/μl ± 5.9 μg/μl, followed by the autumn pool in captivity with 648 μg/μl ± 20.8 μg/μl, the spring pool in captivity 528.51 μg/μl ± 10.59 μg/μl, and, lastly, the summer pool in captivity 1 with 387.9 μg/μl ± 5.6 μg/μl. The PLA2 was purified from the venom obtained from independent fractions 27, 39, 26, and 27 (n=60) of spring, summer, autumn and winter, respectively. The autumn sample showed higher hemolytic activity and the lowest activity was shown in the winter sample. We conclude that venom samples from captive rattlesnakes showed higher concentrations of protein compared to samples from wild snakes, in addition there were variations in the hemolytic activity according to the time of year.

Proteomic analysis of ontogenetic and diet-related changes in venom composition of juvenile and adult Dusky Pigmy rattlesnakes (Sistrurus miliarius barbouri)

Snake venom proteins show high levels of variation at the level of the individual yet the environmental and molecular mechanisms that generate this diversity remain unclear. Here we report the results of a controlled feeding experiment combined with proteomic analyses of periodically collected venom samples to assess the roles of ontogenetic and diet-related effects on venom composition of captive juvenile and adult Dusky Pigmy rattlesnakes (Sistrurus miliarius barbouri). Juvenile snakes fed from birth with mice, lizards, or frogs showed little evidence for an ontogenetic shift in venom composition from 5 to 26 months in terms of substantial changes in the relative abundance of major classes of venom toxins. However, there were fine-scale changes in the relative abundance of D49-PLA₂ 15, PI-SVMPs, and PIII-SVMP 28, and a decline in the abundance of other PIII-SVMPs. Although juveniles raised on different prey exhibited distinct relative toxin compositional change rates, at 26 months old, their venoms showed similar patterns of protein composition suggesting little effect of diet on the overall make-up of venom in snakes this age or younger. In contrast, adult females raised on different prey over a 26 month period showed prey-related changes in the relative abundance of major protein families from initial to final samples. Specifically, mouse-fed females showed substantial increases in the relative abundance of total PLA₂s and serine proteinases of 95% and >100%, respectively, whereas comparable values for lizard- (42% and -22%) and frog-fed females (2% and 11%) were distinctly smaller in magnitude. Venom from adult snakes fed on different prey also showed distinct changes in the abundance of PLA₂ molecules 15, 19a, and 19, which were, respectively, (>100%, 33%, 63%), (>100%, 0%, 35%), and (71%, 20%, -4%) for the mice-, lizard-, and frog-diet. Venom from snakes raised on frogs contained a small (1.1%) but consistent amount of a PLA₂ molecule (15a) not present in snakes fed on mice or lizards. This work provides evidence that venom composition is somewhat plastic in both juvenile and adult S. m. barbouri and that, at least in adults, prey consumed may influence the relative abundance of possibly functionally-distinct classes of venom proteins.

Duration of strike‐induced chemosensory searching in long‐term captive rattlesnakes at national zoo, audubon zoo, and San Diego Zoo

AbstractRattlesnakes typically strike and release adult rodent prey. Striking is followed by a sustained, high rate of tongue flicking that guides the snake to the envenomated, dead prey. Wild‐caught rattlesnakes exhibited this chemosensory searching for about 2.5 h, and the present study demonstrated that long‐term captive rattlesnakes (Crotalus atrox, C durissus, C horridus, C vegrandis, C unicolor) at three zoos did the same. Because these zoo‐raised snakes had always been offered dead rodents and because the snakes had become accustomed to ingesting them without striking, the present snakes had rarely exercised their innate predatory repertoires. The duration of chemosensory searching in these snakes indicates that this important aspect of the predatory repertoire had not been degraded as a consequence of long‐term captive husbandry.

Rate of tongue flicking by rattlesnakes during successive stages of feeding on rodent prey

Specimens of each of three species of rattlesnakes (Crotalus enyo enyo, C. durissus culminatus, and Crotalus vegrandis) exhibited no tongue flicking prior to striking live mice during a regular feeding session. All snakes flicked their tongues at high rates (more than 20 flicks/minute) between striking and commencement of swallowing. Also, frequent tongue flicking (10 to 15 flicks/minute) was seen for about 15 min after swallowing. These data indicate that well-acclimated, captive rattlesnakes do not rely upon the Jacobson’s organ to detect prey or to guide the predatory attack, but that they do use this sensory system to locate prey after striking. Since an envenomated rodent may wander several meters prior to dying, Jacobson’s organ may be very important in finding such prey. It is also of interest that renewed tongue flicking occurs after swallowing. A hypothesis is offered concerning the role of the latter behavior.

Surgical Removal of the Poison Glands of Rattlesnakes

T HE complete removal of the venom glands in poisonous snakes is apparently not a common operation. The writer, who began his attempts to render captive rattlesnakes safe by extracting both the fixed and the reserve fangs, soon discovered, as others had found before him, that this procedure is usually followed by a mouth infection, to which the animals succumb in spite of all subsequent efforts at disinfection of the wounds. Consequently the safer but more elaborate operation of taking away the poison glands was devised. The purpose of deglanding the snakes was to render them more readily amenable in physiological experimentation. A certain amount of technical equipment is necessary for the operation; also the help of an assistant to bind the snake, to act as anesthetist, to prepare the tray of aseptic instruments, to hand ligatures, etc.-for only the operator need have his hands sterilized. Were one to work single-handed, one would employ a water-soluble anesthetic, e.g. dial or nembutal, by means of which the subject may be rendered and kept inert for long hours on end. It is only because rapid recovery of the animals was desired that volatile anesthetics were in general preferred to those whose action is longer lasting. The snake is placed at first in a glass-covered box containing dilute chloroform vapor. There it is left for a matter of twenty minutes to threequarters of an hour. After its head has drooped and it has ceased to respond to prodding stimulation, but before its body has become limp and lost its tone, it is laid lengthwise on a flat board placed on a narrow animal table. With strips of sticking-plaster, arranged at intervals athwart its body and secured to the wood with thumb tacks, the subject is gullivered to the board. If the snakes are of uniform size, any one of them can equally well be held by being dropped, tail first, into a brass tube of suitable diameter and of a length sufficient just to leave the head and neck and the muscular part of the tail free at the ends. A transverse bar of metal soldered to the tube keeps it from rolling. With this device it suffices to apply sticking-plaster only to the neck and to the tail. At all times, but particularly when the subject is a large and powerful one, it is necessary to give careful attention to the fixing of the neck. A glass tube, connected to a rhythmically acting air-pump and ether bottle, is then inserted into the trachea. The sides and top of the head are next painted with tincture of iodine. The tracheal tube is momentarily removed, and the area of operation covered with a dry sterile cloth so slit as to allow only the head to protrude. On second insertion of the tracheal tube, this time on top of the sterile cloth, the animal is ready for operation. The depth of anesthesia is gauged at intervals by observing (1) any spontaneous bodily movements, (2) reflex withdrawal of the tongue when it is grasped with forceps, (3) reflex coiling of the tail when the area of black skin at the base of the rattle is tweaked. In general the anesthesia is so adjusted as to abolish all spontaneous movement and yet leave the former of these two reflexes present. Total abolition of the tongue reflex means unduly deep anesthesia. As in any surgical operation, sudden cessation of hemorrhage at any stage is an indication that the circulation is failing from overdosage