Step right up! Behold a Two-headed Snake!

Clients of mine who breed corn snakes recently had this very unusual baby hatch out of an egg in their incubator, a two headed snake! The hatchling appears to be a pair of conjoined twins which is very rare indeed. We occasionally see two-headed snakes hatching and it is usually a random event; a freak coincidence causing fusion during early embryonic development known as polycephaly.

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In any case, most two headed snakes look to all intents and purposes like a single snake body with two heads side by side on a single neck. This hatchling however is conjoined much farther down the body, just above the level of the heart so it appears from X-rays I took that each head has a separate throat, windpipe (or trachea) and oesophagus that carries food to the stomach. This most likely resulted from fusion of monozygotic or identical twins during the early stages of development within the egg. It was extremely difficult considering the tiny size of the creature to obtain good diagnostic quality X-rays especially as the animal was conscious and difficult to keep it still to take a shot, so the exact anatomy is still unclear. I didn’t want to risk anaesthetising such a fragile, tiny creature just for interest sake to look at its anatomy but from what I can make out it seems like there is one dominant animal with relatively normal anatomy and the other has fused just above the level of the heart. I think there is a single heart, stomach and other abdominal organs, although there is a lot of air so there may be two lung spaces, unusual in that snakes usually only have a single functional lung.

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Other problems that are evident are that the spine is kinked in a few places, which may cause problems down the line, although plenty of minor kinked snakes do lead perfectly normal and pain free lives. The good news is that the little snake has now eaten its first meal, and appears to be doing well. Whether it survives long term is still unknown however. There could be invisible problems we are not yet aware of. If it does survive it would be very interesting to perform more advanced imaging such as MRI to determine the anatomy, but of course this is all academic as there would be no benefit to this little snake, or should I say snakes! Surgical correction is not possible and would result in the death of one or both animals. The main concern in the near future is whether quality of life can be maintained.

More information on the underlying causes can be found here:

http://genetics.thetech.org/ask/ask299

http://news.nationalgeographic.com/news/2002/03/0318_0319_twoheadsnake.html

Can you see my heart beating? A snake with a very big problem!

Snake transport box

I received an unusual phone call recently from the owner of an 18 month old False Water Cobra (Hydrodynastes gigas), a South American rear-fanged, mildly venomous species of snake (http://www.reptilesmagazine.com/Snake-Species/False-Water-Cobra/). The owner had noticed shortly after acquiring the snake that it had what was described as a wound on it’s underside through which you could see it’s insides! Naturally, I was quite worried so asked for the snake to be brought in for examination, and in the meantime they emailed me some photos and reassurance that the snake was acting perfectly normally, eating and defaecating fine and didn’t seem in any way bothered by the strange ‘wound’.

False Water Cobra Hospital Vivarium on AdmissionFalse Water Cobra Hospital Vivarium on Admission 1

Having examined the animal, it appeared that she had a defect in the body wall on her ventral surface or belly with a large hole visible in the ventral muscles. Bizarrely, this defect was at the level of the heart about a third of her length down her body. The only tissue separating her visibly beating heart from the outside world was a thin membranous layer of body cavity lining and some connective tissue which was quite transparent. I have seen some similar lesions in reptiles at the umbilicus or site where the blood vessels carry nutrients into the growing embryo from the egg or from maternal tissues in the case of live bearing species. Sometimes when these animals hatch or are born the hole in the body wall fails to close completely and an umbilical hernia or body wall defect is left behind. However, I have never seen or even heard of such a defect high up on the body overlying the heart! I concluded that this must be a congenital problem that the snake was born with, perhaps a fluke genetic mutation or a developmental insult during incubation of the egg which disrupted the normal growth of the embryo resulting in a physical abnormality at birth. Having spoken to a few reptile enthusiasts in the UK who keep this species of snake, it turns out there have been a few reported with the exact same defect in the exact same place, so it looks likely this is a genetic problem, most likely caused by inbreeding in certain lines due to relatively low genetic diversity in the UK population.

Snake membranous hernia before surgery

The risk of leaving the snake in this condition was that during the course of her life she may snag this fragile membrane protecting her heart and eviscerate herself or worse still puncture her heart. Although this risk was small, it would be safer to carry out a surgery now than always wonder and worry if she might do some damage and seriously injure herself, when pulling off her shed skin for example. I admitted her and set her up in our reptile ward in a heated vivarium to bring her body temperature up to preferred range. Once her temperature was correct I injected her with a combination of sedative drugs into the muscle in her back. I say I injected her, but actually I restrained her with a thick pair of gloves whilst my nurse Justyna gave her the injection. She was very feisty, strong, and objected to restraint, trying to bite the gloves. Obviously considering her potential to give a painful bite and possible envenomation we took great care at this stage. Rear fanged snakes are different to other venomous species in that they have modified salivary glands and teeth at the back of their mouth, with which they chew their prey in order to inject and subdue it. Therefore it would be difficult to get a dangerous bite  from a rear fanged species unless you allowed the snake to chew on you. Front fanged species can deliver a dry or wet bite from the front of the mouth with a rapid strike and minimal contact so are far more dangerous to work with and handle. After her injection we left her back in her hospital vivarium in the correct temperature to allow her to metabolise the drugs efficiently. Ectothermic or ‘cold-blooded’ animals such as reptiles rely on external temperature to control their biological functions and metabolic rate, so it is vital when treating ill specimens and indeed when undertaking anaesthesia and surgery to maintain their body temperature in the correct range so everything runs smoothly and drug dosages work effectively. After about a 20-30 minute induction period, now nice and relaxed after her sedation we removed her and placed her into an anaesthetic gas chamber so she fell further asleep and we could position and prepare her for surgery. She was maintained under anaesthesia by using a gas mask delivering a safe gaseous drug called Sevoflurane. Normally for a prolonged surgical procedure in a snake I would intubate the animal with a solid plastic or rubber tube placed into the windpipe or trachea for better control and access to her airway should she stop breathing for instance, but in the case of venomous species I prefer not to mess around in the mouth due to the risk of accidental envenomation. A correct sized mask with her head taped inside in place and sealing the entrance provides the next best option and is safer for all involved.

Snake anaesthesia preparing for surgery

 

Here’s a video link showing the heart visibly beating underneath the membranous layer of the abdominal wall defect:

Once Justyna prepped her with a surgical scrub and insulating layers to maintain her body temperature lying belly up on a surgical heat mat, I was ready to begin. I carefully dissected away the thin membrane covering her heart from the scales on either side of the deficit. I had to be extremely careful as this layer of tissue was so thin and the heart was literally beating against it directly underneath. Tiny blades and scissors were required, and I cut in time between the beats to avoid cutting at the moment the heart filled to maximum capacity with blood. Myself, Justyna and the veterinary student who is seeing practice with us this week to learn more about exotic pet medicine were all holding our breaths at times. Credit to the student Conor for taking the photographs while I operated by the way. Justyna found this anaesthetic very easy to monitor throughout as we were literally watching the heart beating throughout so she could record heart rate and strength with the naked eye for a change! Often we use sensitive probes to monitor heart rate through the body wall but not needed in this case.

And here is a video during the surgery when I had carefully dissected away the thin tissue revealing the heart beating underneath before I began to suture the defect closed:

Once the tissue had been separated away from the half sized scales lining either side of the lesion I set about suturing the hole back together, bringing the soft tissue of the internal body wall and the edges of the scales together to meet in the middle and form a tight seal which would heal and protect the heart and blood vessels underneath. I was quite happy with a neat and tidy job at the end. She was given a long acting pain medication and anti-inflammatory by injection, and a reversal drug for the sedatives given earlier and placed back in a clean dry cage with paper substrate to recover. We turned up the heat temporarily to boost her metabolic rate and aid her clearance of the anaesthetic drugs, and within 20 minutes she was groggy but wandering around her cage getting her bearings again. It always surprises me how tough these animals are. Reptiles have been around for millions of years and they really are quite resilient and remarkable in what they can withstand. Many of my clients fret and worry about anaesthetic risk in particular if their pet reptile needs a surgery for example. Although the general risk is higher than in dogs and cats I find them to be remarkably sturdy anaesthetic patients for the most part, so the risk is still quite low as long as you seek out an experienced and knowledgeable reptile vet.

Snake repair after closure

 

In terms of aftercare, she just needs to be kept clean and dry. No antibiotics were prescribed as it was a sterile op and good hygiene practices should prevent infection from here. Being a semi-aquatic species that likes to bathe in water, I’ve specified that she is not allowed a water dish in which she could submerge as the wound could act as an entry point for water and bacteria or other contamination into the body cavity if she submerged in the coming week or so. I will keep her in overnight and send her home tomorrow. So far she is making an excellent recovery. The sutures I placed are dissolvable over time and should slough off the next time she sheds her skin or possibly after that, so I just need to recheck her in a week to make sure the wound looks good, is healing well and is free of infection. Problem solved!

Snake in recovery

Thiamine (Vitamin B1) Deficiency in Garter Snakes

Neurological garter snake

Neurological garter snake

This week I was presented with a sub-adult red-sided garter snake (Thamnophis sirtalis infernalis), a North American species of snake which feeds primarily on fish and amphibians in the wild. In captivity these snakes are often fed on fresh or defrosted fish, as well as earthworms, live goldfish or other feeder fish such as minnows or guppies, and pinkies or baby mice.

The snake had suddenly shown a minor head tilt and by the following day was found turning upside down unable to right itself. The owner who is quite knowledgeable on reptiles brought it down immediately for me to examine as timing is of the essence in treating reptile patients. Often they hide signs of illness until a disease is quite advanced, due to being prey species in the wild, so the owner recognised the urgency of seeking veterinary treatment.

The most common differential or suspected diagnosis for a presentation such as this, a garter snake with neurological signs, is a thiamine (Vitamin B1) deficiency associated with captive diet provision.  A deficiency in this vitamin leads to inflammation and destruction of cells in the central nervous system resulting in symptoms such as head tilt or wobble, torticollis (twisting of the neck), opisthotonus (stargazing), nervous tremors, incoordination, convulsions, apparent blindness and death.

In the video link below on my Facebook account you can see how the snake was off balance and incoordinated, as well as ‘stargazing’ or throwing it’s head back over it’s body to the sky:

The issue with captive diets is that they often rely heavily on a single, readily available species of fish. Many fish species, both freshwater and saltwater, contain an enzyme called thiaminase which degrades thiamine or vitamin B1 from the diet. If such species are fed over long periods a deficiency in this vitamin occurs causing the clinical signs outlined above. There is some confusion as to the role of freezing and defrosting fish to feed to garter and other piscivorous or fish-eating snakes such as the water snakes (Nerodia spp.) as well as freshwater turtles and terrapins that rely heavily on fish based diets. In certain species of fish the naturally occurring thiaminases in the flesh are not destroyed by freezing, therefore when they are fed exclusively the thiamine in the diet is depleted and deficiencies occur. Some loss of thiamine in frozen defrosted fish can be prevented by defrosting the fish in hot water (80C for 5 minutes) which denatures the enzyme, although this has some disadvantages in that it can reduce the nutritional value of the food further. Some owners will add a vitamin B1 supplement to the food to counteract the depletion of thiamine. However, the best option for feeding fish to piscivorous reptiles is to feed fish species which have very little or no thiaminase enzyme in the first place. Many readily available and traditional food choices for garter snakes are poor choices due to their thiaminase content, feeder goldfish being a perfect example. Goldfish actually contain high levels of thiaminase despite being the most widely available feeder fish and most widely recommended for garter snake food!

The owner of the snake I treated this week fed frozen defrost Smelt to her garter snakes, along with fresh trout and salmon. All of her garter snakes were very healthy and thriving on this diet so there was some confusion and disappointment as to why I thought this one had succumbed to hypovitaminosis B1. It turned out that this particular animal was quite a fussy feeder compared to the other individuals and rarely accepted a meal of trout or salmon, but rather fed almost exclusively on the defrosted Smelt. Smelt is a readily available frozen feeder fish, which contains relatively low levels of thiaminase compared with many other sources such as mackerel, goldfish or whitebait, but if fed exclusively for long periods can result in the thiamine or B1 deficiency over time. My plan for treatment was to administer high dose injections of Vitamin B1 and monitor the response to treatment. A positive response to treatment with reversal of the clinical signs confirms the diagnosis in these cases. I gave two injections 3 days apart, the second of which was today and already the little snake is doing much better; more alert, responsive with normal coordination and mobility, and no longer twisting or flipping over. Only a very mild head tilt remained, which I anticipate will have disappeared once it comes back at the end of the week for the last vitamin injection. In severe or advanced cases the neurological damage can be too severe that the central nervous system particularly the cerebral cortex of the brain becomes necrotic and the animal fails to recover. Luckily in this case the vigilant owner brought the patient in in time to save it.

Garter snake recovered and moving normally

Garter snake recovered and moving normally

In future, I recommended Smelt should only be used as an occasional convenient source of food, not as a regular component of the diet. The owner will have to make efforts to introduce more variety into the snakes diet with earthworms, pink mice, feeder fish species that lack the thiaminase enzyme such as guppies and platies, or commercially available fresh and frozen fish species again that lack thiaminases such as trout and salmon and some other native freshwater angling species. It may be difficult to convert this fussy feeder onto new food sources, in which case the Smelt could be used to scent new foods until they are readily accepted.

Here is a video of the snake after three vitamin B1 injections a week later, moving much more normally, more alert and responsive than before:

 

For further reading on this topic have a look at these links:

http://www.gartersnake.info/articles/2012/all-about-thiaminase.php

http://www.ces.ncsu.edu/gaston/Pests/reptiles/gsnakecare.pdf

 

The snake that became unstuck!

Crystal the Royal python got in a rather sticky situation, when she managed to tangle herself in some loose duct tape that was being used temporarily in her vivarium when her owners were installing new lights. Unfortunately in her bid to untangle herself she managed to rip the delicate thin skin on her neck and caused a full thickness laceration exposing the underlying muscle. Her owners were panicked and rushed her down to see me, travelling nearly 3 hours in traffic to get to the surgery. Luckily it was my turn to work the Saturday clinic that day and my afternoon wasn’t as busy as usual so we managed to see her quickly and fix her up before more damage was done.

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Snakes and sticky tape do not mix

Here she is being given some anaesthetic gas and oxygen, after initially being given sedative drugs via intramuscular injection. At this point we couldn’t see the true extent of her injury, but knew it was bad. I was confident however that we would stitch her up and have her reasonably back to normal in no time. I took the opportunity while she was going under anaesthetic to administer pain relief and antibiotic injections to make her comfortable and prevent infection setting in.

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Snake laceration wound

Once she was fully anaesthetised I used surgical spirit to dilute the solvent on the tape and peel it off bit by bit, taking great care not to allow any spirit to contact her delicate tissues underlying her scales or to cause further tears. After removing the tape the area was cleaned and disinfected and prepped for surgery, reducing contamination and minimising the risks of post-operative infection. She was kept on a warm heat pad throughout the procedure to enable her cold-blooded body to maintain it’s metabolism and process the anaesthetic and other drugs effectively. Reptile patients are unique in that all bodily functions rely on external heat from immune function, to heart rate and even breathing rate. Therefore it is vital that they are warmed throughout surgery and maintained in thermostatically controlled conditions whilst hospitalised and in recovery.

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Suturing snake wound

I carefully sutured her skin back together taking care not to cause too much tension and not to invert the scale edges so that the wound could knit back together efficiently and heal quickly. Good surgical technique at this stage was critical to obtain a cosmetic and functional wound that would repair over the coming weeks without causing future problems with shedding skin for example.

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A vet’s work is never done, even on a Saturday evening

Here I am hard at work on a Saturday afternoon whilst all my colleagues (apart from my nurse Sharon assisting on anaesthetic duties) were out in the back car park starting our end of summer barbecue, beers and wine in hand. Now there’s dedication, eh?!

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Python in recovery hospital cage

After she was stitched back together I reversed her sedative drugs with another injection and set her up in a warm hospital cage on a heat pad to recover from her ordeal. By this point her meds ensured she would awake pain free within a couple of hours. Things are definitely slower in my reptilian patients compared with dogs and cats.

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Snake wound sutured post-op

This was the finished handiwork post-operatively. I am happy to say she went home very alert and happy on the Monday morning to her relieved owners and will come back to visit me to remove her sutures in 4-6 weeks.

Cardiac Disease in Reptiles

I would like to share with you two interesting cardiac cases in reptiles which I encountered in the past, both causing heart failure but with different presentations, underlying disease mechanisms and outcomes. Cardiac conditions in reptiles are rarely seen, possibly due to under-diagnosis or not being presented frequently to specialist reptile clinics. This could also be due to various other illnesses and diseases causing the death of pet reptiles before they reach the grand old age when they are likely to present with cardiac failure.

Cornsnake

In any case, I was very surprised to see both of the following cases within two weeks of each other, when in my previous three years of clinical practice I have rarely encountered such problems in reptile species. The first case was a 5 year old female Yemen Chameleon named Blossom. Blossom is an old girl for her species and has now laid 6 fertile clutches of eggs which is a great achievement in itself and a credit to her owners excellent knowledge and care for these specialist reptiles. Chameleons do not make easy pets, but especially females as they often get reproductive and metabolic problems. In fact, Blossom’s owner was concerned that perhaps this time around Blossom was egg-bound or unable to lay her next clutch as she was mated 10-12 weeks previously and had failed to lay any eggs. She was also quieter than usual, had a decreased appetite, was showing darker stress colouration, and her abdomen was becoming enlarged suggesting she may be gravid (carrying eggs).

When Blossom presented to the clinic her physical examination was unremarkable apart from a distended abdomen. I decided to take an X-ray to determine whether she was indeed gravid or egg-bound, or suffering from a condition called pre-ovulatory stasis whereby the ovaries produce multiple follicles but fail to ovulate and progress to laying a clutch of eggs. I was extremely surprised to find that the distended abdomen did not contain eggs or follicles but was full of fluid creating a grainy, diffusely opaque greyish appearance throughout the abdomen and obscuring the abdominal contents. The striking finding on the X-ray however was an enlarged perfectly spherical cardiac outline suggesting heart enlargement. More specifically this appearance indicated an accumulation of fluid in the pericardium or thin membranous sac that surrounds the heart rather than enlargement of the heart itself obscured within this fluid sac.

chameleon pericardial effusion A diagnosis of pericardial effusion was made, which has most likely resulted from primary cardiac failure due to old age and high metabolic stresses or demands throughout Blossom’s life. Secondary fluid accumulation in the abdomen called ascites has resulted from the failure of the heart to pump blood as effectively as normal. This inefficiency in the pumping mechanism leads to fluid pressure building up in the vessels leading to the heart and subsequently fluid leaking from the blood vessels into surrounding tissues and organs, eventually accumulating over time in the abdominal cavity. Other causes for pericardial effusion can include parasitic disease and infection but considering Blossom’s relatively bright demeanour, history, husbandry conditions and age these are unlikely causes in this case. Unfortunately for Blossom this does mean that she has congestive heart failure, which will inevitably worsen with time.

Treatment for congestive heart failure in reptiles is difficult and not a great deal of research has been carried out on the various drugs available in terms of efficacy and safety. The mainstay of treatment in such congestive heart failure cases where fluid accumulation is the most problematic clinical sign is the use of diuretic medications, which encourage elimination of excessive fluid from the body. Unfortunately, the risks of diuretic treatment in reptiles are higher than in mammals as they have a specialised renal system with a unique blood supply to the kidneys. This can therefore render them susceptible to dehydration and kidney failure on diuretics or other medications. Similarly, because treatment would involve injecting Blossom with medication 2-3 times daily, myself and the owner agreed that this would be unfair and cause her far more stress and pain than was humane considering chameleons make for stressful patients at the best of times. At present Blossom is doing well without treatment, so as long as she remains comfortable and her breathing is unaffected we will monitor her progress. I have suggested decreasing the temperatures in her vivarium to the lower end of her preferred optimum temperature zone, and also advised reducing her food intake. Both of these alterations in her husbandry are an attempt to decrease the metabolic demands on her cardiovascular system and hence try to prolong her lifespan as much as possible whilst keeping her comfortable. It will be interesting to see how long she remains healthy and bright, but sadly there may come a time where she dies of acute cardiac failure or we have to consider euthanasia when her breathing or quality of life is compromised. At this point the fact that Blossom has thrived, reproduced and lived beyond her natural lifespan in the wild to succumb to a geriatric disease rarely seen in captive reptiles is a credit to her owners excellent care.

Blossom Chameleon

 

 

 

 

 

 

 

 

The second cardiac case I saw was an old cornsnake, of unknown age due to being rehomed as a mature adult snake. I do not have as much background information for this case as it was seen by a colleague in my previous practice. The snake presented with lethargy and inappetance, having refused food for several weeks. The striking physical exam finding was a large firm swelling in the cranial third of the body corresponding to the site of the heart or possibly the stomach. X-rays (seen above and below) revealed a soft tissue opacity in this region suggesting one of either of these organs was grossly enlarged. Due to the appearance on the X-ray a foreign body ingestion in the stomach could be ruled out. Unfortunately the snake died in clinic so after discussion with the owner a post mortem exam was carried out which revealed the enlarged organ to be the heart. All three chambers of the heart were massively dilated to about three times their normal size and the ventricle was grossly thickened and enlarged. As an aside mammals and birds have four chambers of the heart compared to three chambers in reptiles and amphibians, and just two in fish!

Cornsnake DCM dissectionA diagnosis of dilated cardiomyopathy was made which lead to acute cardiac failure and death in this animal. If the snake hadn’t died this diagnosis would have been made by doing an ultrasound scan to determine what indeed the enlarged structure was. Another possibility I would have been concerned about in this case before seeing the X-rays was a parasitic infection called Cryptosporidiosis which can cause a large swollen stomach in infected snakes manifesting as a firm mid body swelling on physical examination. Again, the most likely cause of cardiac disease was degeneration of the heart and valves associated with ageing. If the snake had presented at an earlier stage of the disease treatment with cardiac medications may have been attempted but unfortunately in this case it was too late.

Cornsnake DCM Lateral 1I hope you found these case studies interesting, and if you have any questions or comments please feel free to ask in the comments section below. Similarly if you have any topics you would like me to write about in future let me know.