Another common reason that snakes are brought to veterinarians for exams is that they are regurgitating or vomiting. Regurgitation occurs soon after eating, whereas vomiting occurs hours or days after ingestion of food. Regurgitated food is generally undigested food expelled primarily from the esophagus (passively, that is, without much force). Uomitus consists of partially digested food, usually actively expelled from the stomach. With reptiles, distinguishing between the two actions can sometimes be difficult. The point is that the snake is not holding down food, and possible causes are numerous.There are ten common causes for vomiting or regurgitation in snakes, but remember that there may be more than one cause for any particular case. A good example of this has been termed "regurgitation syndrome" by Ross and Marzec (1990) which occurs in all snakes, although Ross and Marzec were studying boid snakes at the time the phrase was coined. Following are the ten common causes for vomiting or regurgitation in snakes:
- Handling too much or too soon after feeding
- A sharp (sudden) drop or rise in ambient temperature or just improper ambient temperature for digestion
- Increased stress (including from mating) soon after feeding
- A meal that is too large, too old, or too toxic or offered too frequently
- Bacterial infection
- Protozoal infection (amoeba, coccidian, flagellate)
- Metazoan (worm) infection
- Excessive drinking right after eating
Sometimes, making minor changes to a snake's environment or adding a new animal to the enclosure may be very stressful for the snake and cause it to vomit its last meal. Perhaps the most common cause of vomiting or regurgitation is an ambient temperature that does not allow normal digestion. More frequently, a drop in ambient temperature is the cause of sudden onsets of vomiting or regurgitation, yet it also can be caused by sharp rises in temperature. This symptom should serve as a warning to the herpetoculturist that the normal ambient temperature may be marginal for digestion.
Very large meals may cause irritation of the gastrointestinal tract and may result in vomiting or regurgitation. Toofrequent feedings have the same effect. In snakes, irritation leading to vomiting or regurgitation may also be the result of swallowing a large meal backward; the scales of a fish or the fur of a mammal—which generally are directed from nose to tail—would be pushed up if the prey were swallowed tail end first and would irritate the snake's insides.
If the prey offered has been in freezer storage for a long time, perhaps longer than six months, it may be loaded with bacteria or bacterial toxins, which in some cases may induce vomiting or regurgitation as happens with humans in cases of food poisoning. Some food items, such as certain species of frogs and toads, produce chemical toxins that may be a little more than some snakes can handle.
Bacteria flourish in a filthy environment. Bacteria that are extremely contagious are commonly discovered as the cause of outbreaks of vomiting. These bacteria may be responsible for an inflammation of the lining of the stomach and intestine known as bacterial gastroenteritis. Not surprisingly, two of the contagious gram-negative bacteria, Salmonella and Arizona, are frequent offenders. These bacterial infections are among the few cases in snake medicine in which oral antibiotics are deemed appropriate and necessary. Ross and Marzec (1984) and Ross and Maxzec (1990) have used ciprofloxacin and amoxicillin successfully. The senior author of this book commonly uses ciprofloxacin and enrofloxacin orally in snakes with gastroenteritis, at the doses listed in the drug tables at the back of the book, and it has worked very well.
Since we discuss parasites (protozoan and metazoan) in some detail in the last chapter, we will not dwell upon them here. However, you should always consult your veterinarian if you suspect parasites. It is usually a waste of time and money—not to mention dangerous for the snake—to pump one routine deworming agent after another into a debilitated snake without the benefit of repeated fecal exams or a gastric wash.
A foreign-body obstruction commonly occurs in captive snakes that are housed on the improper substrate. Check your references, and use the proper substrates as mentioned in chapter 2. Towels, hand cloths, and T-shirts are not acceptable; they may be accidentally ingested. Incidentally, you can sometimes induce the vomiting of an ingested towel or hand cloth by lowering the cage temperature. Give the snake a sterile electrolyte solution intraperitoneally to counteract the dehydrating action of the towel. Then place the snake in a relatively cool area, about 50°F to 60°F (10°C to 16°C). Vomiting of these soft objects usually occurs within two to three days under these circumstances. You must monitor the snake for dehydration, and intraperitoneal fluids and antibiotics are advisable during and after this procedure. Note that this is a practical field approach to be used when sedation and endoscopic retrieval of the hand cloth are not possible. This approach is definitely worth considering before attempting surgical retrieval, but you must carefully monitor the state of hydration in these animals. (In a seriously dehydrated snake, its skin has wrinkles that return very slowly or not at all to their original position when gently pulled away from the body)
In older snakes, tumors are definitely a possible cause of regurgitation or vomiting. Your reptileoriented veterinarian can determine if one is present by means of physical examination, endoscopic exam, X ray, or any combination of these.
Many snakes tend to drink heavily after gorging on a large meal. Sometimes, it appears that they may overdrink; vomiting or regurgitation occurs soon afterward.
Dehydration theoretically causes irritation to the lining of the gut by blocking the smooth passage of food because of the increased friction, thereby increasing the likelihood of vomiting or regurgitation.
When vomiting occurs, isolate the animal, restrict handling, lower the temperature of the enclosure as needed, feed less frequently and offer smaller prey, and make sure that the cage is clean and the food is fresh. If vomiting persists, have your snake examined by a reptile-oriented veterinarian, who may suggest a fecal exam, a culture and sensitivity test, or a biopsy to determine the cause or causes of the problem and the proper treatment.