Renal Tumour in a Chameleon: A Case Study.

A one year old male Panther Chameleon presented to the clinic following a one week history of progressive hind limb weakness, loss of motor function, swelling of the left knee and sleeping with his back legs dangling from his branch. He was still eating although his appetite was reduced. His owner was very knowledgeable and experienced in keeping reptiles, and his husbandry and captive care sounded excellent when taking a full clinical history and appraisal. There had been no changes to his routine or care, and no known history of trauma. His left knee joint however was visibly enlarged and swollen compared with the right hand side.

Hind limb paresis unilateral swollen stifle

On clinical examination, the joint was swollen but didn’t appear painful on palpation. However he was demonstrating bilateral hind limb paresis, or loss of motor function. Gripping was much reduced in the back feet compared to the front, and he appeared much weaker on the pelvic limbs also. Similarly he was reluctant to bear weight on the left hind compared with the right. Sensory function was intact and present in all limbs. This examination allowed me to form a reasonable diagnosis of a neurological problem, most likely a spinal lesion in the lumbar region or an intra-abdominal mass placing pressure therefore impinging on the nerves in this area resulting in compression and subsequent loss of motor function. I should mention here that I had seen a photo of this chameleon on a forum I am a member of the previous day when the owner asked for advice. From a photo alone it would have been impossible for me to pinpoint the problem or give a reasoned diagnosis as I could when the animal was in the clinic and I could perform a full neurological examination. For this reason I would always warn owners to beware accepting an online diagnosis based on a photo alone. If in doubt, a vet visit with a reputable reptile vet is really worthwhile.

Hind limb paresis perching

I explained to the owner that based on the issues I was seeing, I suspected an abdominal mass was the worst case but highly likely scenario, so we decided an X-ray was the next step. I took a dorso-ventral view after giving the chameleon some anaesthetic gas to allow me to tape both legs in position so I could get the best image possible to compare the knee joints in the same position. The X-ray however showed a very serious and obvious problem quite apart from the swollen joint. The entire abdomen of the lizard was full of air and the internal organs were all compressed. Air on an X-ray is black, and in normal chameleons the lung shadows demarcated by free gas extend a little over halfway down the length of the abdomen. Chameleons are fairly unique in that they also have finger like extensions or air sacs extending very far back towards the tail end of the body which are lined with a very thin transparent tissue almost like cling film. Therefore this is very prone to rupture from trauma, infection or damage during surgery for example.

DV view

I took a lateral view to confirm the organs were compressed ventrally (towards the bottom or belly of the abdomen), which highlighted that in fact a lung or both lungs were ruptured and air had leaked into the free space within the abdomen. I was also curious to gain another view of the very dense whitish-grey mass in the caudal or tail end of the abdomen just before the pelvis, which was occupying the entire width of this section of the abdomen. Unfortunately, on the lateral view this corresponded to the site of the kidneys and confirmed my worst fear that a kidney mass of some description was responsible for the nerve impingement and neurological signs on presentation. The kidney mass may have been an abscess or a congenital problem such as hydronephrosis present from birth which was gradually causing a growth in size over time. Similarly it may have been a tumour but it was difficult to tell from X-rays alone. The swelling of the joint in the left knee could have been explained by trauma associated with reduced motor function, the assumption being that he injured it in the preceding days whilst dragging it behind him.

Lateral view

The prognosis based on a renal or kidney mass of that size no matter what the underlying cause was unfortunately quite grim, not to mention the issue of air within the abdomen causing breathing problems and compression of other vital organs. After lengthy discussion with an upset owner, it was decided that it would be fairest and most humane to put the chameleon to sleep and prevent further suffering. Any treatment or further diagnostics would have had to be very invasive and highly unlikely to bring a resolution to the problem. In order to bring a resolution to the case and for the sake of education, the owner kindly allowed me to open the abdomen following euthanasia in a post mortem examination to confirm my diagnosis of a renal or kidney mass, and ascertain the nature of the lesion. Sadly my suspicion of a renal tumour was confirmed; quite a surprising diagnosis in such a young animal you might say. However renal lymphoma, which is one of the more common cancers in reptiles, is unfortunately not exclusive to older animals as in many other cancers. Several other cancers are also reported in reptiles. In this case, the classification of the tumour would not affect the outcome of the case so I did not send any tissue samples for pathological classification. A very sad case, but the positives if any can be taken from it were that I and hopefully other veterinarians can learn from this little chameleon’s death. I’m therefore very appreciative to the owner for allowing me to write this up and share the case study.


WARNING: THE FOLLOWING PICTURE IS GRAPHIC IN NATURE, SHOWING THE POST MORTEM FINDINGS. PLEASE DO NOT VIEW IF YOU ARE SQUEAMISH OR EASILY OFFENDED. I INCLUDE IT HERE FOR EDUCATIONAL PURPOSES ONLY SO THAT SIMILAR CASES MAY BE DIAGNOSED EARLIER IN FUTURE WITH THE EXPRESS PERMISSION OF THE OWNER OF THE ANIMAL IN QUESTION.

PM findings labelled

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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.