The healthy snake is a sleek, symmetrical, well-muscled animal, covered in smooth scales from the nose to the tail tip. Even the eyes are covered by clear scales, called spectacles. Internally, the snake's organs line up, one after the other to accommodate the long thin body. This anatomy is unique to the snake, but the location of the organs is predictable. As part of your pet's routine annual check-up, your reptile veterinarian will examine your pet externally and with the practiced skill of palpation, he will use his hands to feel the internal organs. Knowledge of the anatomy of a snake, the location of the organs and the normal variations of those organs allows your veterinarian to make a preliminary assessment of your pet's health.
The loss of the normal svelte physique and smooth lines often points to health concerns. Pet snakes should be observed daily for changes in their physical appearance or behavior. In addition, most should be handled regularly, and should have their eyes, mouths, skin and vents inspected. When you hold your snake, pay attention to the texture of his skin and to his muscle tone. As he slithers through your hands, take note of any segments of his body which stiffen or do not move normally. A swelling inside your snake will be felt before it can be seen and unusual masses or lumps within or under the skin, or within the body should be investigated with the help of a reptile veterinarian.
- Parasites. Lumps on the surface of the skin are often caused by mites, ticks and other external parasites. These are most often found around the lips, eyes, and cloaca, and when watched carefully with the naked eye or with a magnifying glass, will often move.
Both ticks and mites can transmit bacterial and viral disease. In sufficient numbers, ticks can take enough blood to cause anemia in a snake. Mite and tick infestations often contribute to dysecdysis (abnormal shedding). Treatment of parasites is directed at both the snake and possible parasite reservoirs, or mites, in the environment.
Some worm-like parasites form cystic structures underneath the skin. Superficially, these may appear much the same as lumps, like abscesses. Treatment, however, is quite different, and some testing or investigation is usually required to reach a diagnosis. Encysted parasites are most commonly seen in wild caught individuals, and may require surgical as well as medical therapy.
- Abscesses. An abscess is a pocket of bacterial infection, which in snakes may appear as a firm lump. Pus formed by snakes is solid, unlike the liquid pus formed by mammals. Because the pus cannot be drained, an abscess may require surgical, as well as medical therapy. Abscesses can be just a millimeter or two in diameter, or can grow very large. They may have a scab on the top. These bacterial infections can form at the site of a bite from live prey, cage mates or parasites. In these cases the bite mark may be obvious.
It is also common for snakes to develop many small abscesses within or just under unbroken skin. These are more easily felt than seen. If the infection did not arrive through external trauma, such as a bite, scratch or burn wound, it must have arrived internally. Frequently, skin infection is the outward manifestation of a more serious internal problem, septicemia, or blood poisoning. In these cases, the bacterium that causes the abscesses has been disseminated throughout the body, although we may only see the effects on the skin.
The source of bacteria is usually the snake himself or the prey. Most bacteria, given the right conditions and a host with a weakened immune system, are capable of causing some sort of disease. Some of the bacteria found on and in the body of a healthy, normal snake have the potential to be particularly dangerous. One of the best known is Salmonella. Potentially dangerous bacteria are also found in the snake's mouth, his digestive tract and waste. Some are found in the blood stream. When the environment is clean and well suited to the species, a snake in good health will not usually become ill; his immune system keeps the bacteria in check. Usually as a secondary invader, fungi can also become involved, complicating an already serious condition. Bacterial and fungal skin infections are generally related to a husbandry problem and should be treated by a veterinarian.
Blister disease is a life-threatening condition in which fluid-filled pockets form under the scales, lifting the scales. The surrounding skin may be abnormally pink, red or moist. These blisters are painful and are prime entry points for bacteria and fungus. Blister disease is largely due to improper husbandry. Usually the environment is inadequately heated, too moist or too dirty. Some bacterial or viral infections cause inflammation of blood vessels, interfering with normal circulation. The resulting fluid build-up can appear similar to blister disease. It is important to inspect the underside of your snake for irregularities in the color and normally smooth, dry contour of the large belly scales.
- Cancer. Cancer can be defined as new growth of body tissues, which is not limited by the usual control mechanisms and while not serving any physiologic purpose, usually occurs to the detriment of the animal. Any of the body's tissues can be affected, including the skin.
The appearance of cancer can take many forms, including lumps within or under the skin, blisters, sores, abnormal feeling or discolored skin. Testing will likely be necessary to distinguish cancer from other skin changes and to give a prognosis. Some cancerous growths may be surgically or otherwise treated, while others, because of size, location or tumor type, cannot be treated.
Based on your snake's history, your reptile veterinarian may begin to narrow the field of possible diagnoses. Your snake's vent should be clean and smooth. Swellings in front of the vent area can be due to a mass in the cloaca, in the reproductive tract or in the colon. Masses include retained eggs, fetuses or very firm stool. Cloacaliths, stone like formations of urate (the white, semi-solid portion of the urine) can also form in the cloaca. All of these may act as a blockage, preventing the passage of waste, and in some cases, the remainder of the clutch of eggs or fetuses. Swellings around the vent, or within the tail may indicate infected scent glands or hemipenes. Protrusions from the vent are usually prolapsed internal organs. These may include reproductive structures (oviduct, hemipene), part of the colon, or the cloaca, and should be dealt with by a veterinarian immediately.
Deviations or lumps in the spine can be due to congenital defects or malformed vertebrae. They are also seen in cases of severe malnutrition and as a result of trauma. Bone infection or osteomyelitis can occur where a bone has been broken or otherwise damaged, perhaps by a fall or other blunt trauma. In the case of a snake, the spine or ribs may be affected.
Other metabolic and possibly viral conditions exist in snakes which can cause spinal deformity. This includes Osteitis Deformans, a disease much like Paget's disease, seen in humans. Bone swellings can be detected in the ribs or more likely along the spine. There may be a single area of firm swelling, or an area of spinal deviation, either a sideways “kink” or a protruding lump. The area might be painful to the snake, and he might be reluctant to move or have difficulty moving. An examination by your reptile veterinarian, the snake's history and radiographs (X-rays) are the first steps in determining the nature of a bone swelling. Further tests might be relevant and are discussed below.
Internal Lumps or Swellings
It is common to feel the prey within the digestive tract, particularly in lean, fit, recently fed snakes. The snake's stomach is located approximately midway between the head and the vent. After this point, the prey is sufficiently digested that it should not be easily felt. That said, it is recommended that snakes not be handled for at least 48 hours after they have fed, to minimize the risk of regurgitation.
Swellings or lumps associated with the gastrointestinal tract can be abnormal. Undigested prey can cause a swelling in the stomach (mid-body) region of a snake whose housing conditions (particularly temperature) are not adequate. Food may be physically prevented from passing through the digestive tract by an obstruction. Such obstructions can be created by parasites, foreign bodies, previously undigested meals, tumors, abscesses, granulomas (bacterial or fungal masses), force feeding or the feeding of too large a meal.
Viral, bacterial, fungal and parasitic conditions can thicken the lining of the digestive tract and affect its ability to digest and propel food, causing a functional, if not physical obstruction. Snakes suffering from serious or systemic disease such as kidney or liver failure may not have normal intestinal motility. Snakes kept in conditions which are not warm enough will be unable to move food through the gastrointestinal tract at a normal pace.
Ingested material can become lodged at any point along the digestive tract. Snakes whose prey is too dry, who do not have access to water or whose environment is insufficiently humid may suffer from chronic dehydration and will easily become constipated. It is possible to see snakes who have not had a bowel movement in some time and have several fecal masses palpable in the colon. Lumps adjacent to the digestive tract can put pressure on intestinal contents, preventing their passage.
Female snakes in breeding condition may have large developing follicles on the ovaries. These can be palpated by experienced people, but this is not recommended in most cases as follicles are extremely delicate and can burst with handling of the snake. Although the young of live-bearing or viviparous snakes may be detected as a swelling in the last half of the body, the eggs of an oviparous snake are more easily felt and recognized for what they are.
Swelling associated with the reproductive tract may also be abnormal, associated with egg binding, retained fetuses, tumors or infection.
Enlarged livers, kidneys and other internal organs may be palpated with skill. These may reflect infection, cancer, cysts, degenerative or metabolic disease.
Obesity is a common problem among captive snakes. In addition to other health risks, obese snakes are difficult to palpate, as the organs are surrounded by fat. These fat deposits can become lumpy and in some cases inflamed, particularly in the case of snakes fed obese prey. Palpation alone will not differentiate between fat and a more sinister lump.
Virtually all the internal organs can be affected by disease, some more commonly than others. Internal abscesses, granulomas and cysts are seen in snakes and if large enough will be detected directly by owners or veterinarians. Entire organs or tissues may also enlarge enough to be physically detected as an internal mass. Enlargement may be due to bacterial, viral or metabolic conditions. Tumors or cancer are also not unusual in snakes. These have been recognized in the skin, muscles, liver, kidney, reproductive tract, bone and eye, among many other sites.
In most instances, when presented with a snake with a lump, your veterinarian will follow a sequence of steps, which should allow him to arrive at a diagnosis.
- History and physical. First he will take a history, to understand the background of both the lump and the snake. He will also question you as to the snake's diet and environment, with particular attention to the temperature and humidity. Then he will perform a physical examination. In some cases this will be enough for your veterinarian to be able to make recommendations or to prescribe treatment. In most cases, he will prefer to have more information.
- Blood tests. These allow for the evaluation of function of organs such as the liver and kidneys, and even when a mass does not involve these organs directly, their role in the snake's overall health is important and needs to be assessed. An evaluation of the red and white blood cells can indicate anemia or sub-clinical, that is undetected, disease. In the case of bacterial, viral or fungal conditions, blood tests provide a means to diagnose disease, assess its severity and monitor response to therapy.
- Bacterial or fungal culture. In the case of skin lumps, infection is often suspected, and your veterinarian may take a sample of the lump contents to assess the infectious agent and to choose the best treatment.
- Radiographs (X-rays). Radiographs are often used to assess internal organ enlargements. They may reveal changes to the skeleton, retained eggs or fetuses, foreign bodies or other masses. If the lump in question involves the digestive tract, it is common to tube-feed the snake with barium, which will coat the digestive tract and show up as bright white material on the radiograph, outlining any masses, obstructions or abnormalities.
- Fecal testing and stomach washes. These may reveal parasites, which may directly or indirectly cause swelling of the digestive tract. Particularly in the case of fecal testing, fresh samples are best. A sample containing no parasites does not necessarily indicate that the snake is free of parasites. Serial samples are often required.
- Endoscopy. A fiber-optic endoscope, which is like a very small microscope on the end of a slim rod or cord, allows internal examination through a small incision or through the mouth. The extent of the problem can be assessed this way, avoiding more invasive procedures. Biopsies or samples for culture can also be obtained this way.
- Biopsies and fine needle aspirates. Relatively large samples comprised of up to a few millimeters of tissue (biopsy) or just a few cells aspirated through a needle directed into a lump (fine needle aspirate) can be revealing when examined under a microscope. Depending on the circumstances, this test may be done by your reptile veterinarian, or at a laboratory by a veterinary pathologist. Biopsies and aspirates are often taken from the skin or other superficial lumps, but are also used as part of an exploratory surgery. For example, a snake with a mid-body swelling, which appears by palpation and on a radiograph to be an enlarged liver, might undergo an exploratory surgery. The intent of the surgeon is to be sure of the origin of the swelling, and should the swelling be a foreign body in the gastrointestinal tract, or an abscess, it can be removed. However, if the lump inside the snake is discovered to be a swollen liver, it obviously cannot be removed. However, a small sample of liver (that is, a biopsy) can be taken. This can be examined microscopically, in an effort to reach a diagnosis of the type of liver disease and to determine an approach to treatment.
It is not unusual to find a lump on a pet snake. Changes in your pet's body, which manifest as lumps, either on the skin or within the body are seldom normal. Regular inspection and careful handling of your pet snake will allow you to detect these changes as early as possible. The causes of masses or lumps are many and varied but are always worth being examined by a reptile veterinarian, because a number of conditions, some serious and some not, can appear the same at first glance.
In most cases, a detailed history and a thorough physical examination will be sufficient to narrow down the possible diagnoses. At this point your veterinarian may have a good idea as to the extent and general nature of the problem. Your reptile veterinarian should be able to explain to you why he recommends a given test or tests, and should be able to help you to choose an approach that meets your budget and also addresses the needs of your snake. This may be as simple as a few husbandry changes or basic, inexpensive tests.
In the event of a more complicated or more serious condition, a reptile veterinarian will be able to outline a stepwise investigation, designed to lead to a definite diagnosis, a prognosis and a treatment plan. It is almost always worth trying to reach a definite diagnosis; once we know what to call the problem, we can address it logically.
Reptile medicine has made huge advancements in recent years, and tests and treatments are improving along with our knowledge of reptile disease. Many disease conditions remain to be understood, and no doubt many are yet to be discovered. Reptiles never fail to surprise those of us who work with and care for them; a step-by-step, scientific approach, will inevitably lead to improved medical care for all snakes, as well as to the best treatment options for your pet.