Leopard Gecko weight worry

Question
QUESTION: One of our two leopard geckos has lost a lot of weight recently. Her tail is now thin through the length of it. Her colour is good, eyes bright, and she is eating well. The other gecko is huge in comparison. Her tail is chubby at the base, as I believe it should be. Do you have any ideas what could be wrong? We are thinking perhaps a parasite, or worms or something internal? In 7 years they have never been ill.
Thanks.

ANSWER: Hello Emma,

Are your geckos both female, or do you have a male & a female?
What type of substrate do you have, sand, tiles, papepr towels?
Since she is losing weight, that would be my first thought also, parasites or worms.  Can you get a fecal done on her?  
If she is not eating, you will need to intervene for awhile so she doesn't keep losing weight.  Try using chicken, turkey or beef babyfood to feed her.  You can use a a plastic dropper to drop food onto her nose & once she tastes it she should lick some of it off for you.

What type of feeders do you use?  Are you supplementing calcium regularly?  

Tracie

---------- FOLLOW-UP ----------

QUESTION: Thanks for your prompt response.
They are both female.
We have calci-sand substrate, as advised when we first bought them.
Where/how would I get a faecal done? (We are in London, UK)
We feed them only live locusts, occasionally dusted in multi-vitamins, and whenever we put them in the viv, she is the first to catch at least one...so I know she's eating - hence the parasite/worm theory!
Emma

ANSWER: Hello Emma,

Well, most vets should be able to do a fecal exam on her, even if they are not an exotic vet.  A fecal exam is the same no matter what species they are.
If she is losing weight like, it would almost have to be worms stealing nutrition from her.
I do recommend not keeping them on calcium based sand though.  They can become impacted from it & the sand does not stay clean very well which can contribute to parasite infestations.  
The locusts are fine.  I would keep a small dish of calcium in the tank too, so they can lick that when they need extra.
Good to hear that she is eating.  I would get a fecal done on her though, that would tell us a lot.

Tracie

---------- FOLLOW-UP ----------

QUESTION: Thanks Tracie.
I've contacted our nearest vet, and will organise the faecal.
We were told by the herpatologist we bought them from (now closed down) that calci-sand was the best substrate for leopard geckos. What alternative would you recommend?
Emma

Answer
Hello Emma,

Hm, well, unfortunately, calcisand causes horrible & fatal impactions.  It is calcium based & when ingested, it clumps up like cement making it virtually impossible to pass through.  Their gut & intestines fill up & causes nutritional deficiencies & damages the microvilli & brush border.  I lost one a long time ago due to impaction of that sand.  
The best substrate for them is non adhesive shelf liner, tiles, paper towels or felt.  Now, if you want to use sand, you could try washed & sifted playsand because that doesn't clump together like the calcium based sand does & can pass through more easily.  As long as he doesn't ingest it, he should be ok on that type of sand, but I normally don't recommend loose substrates for captive reptiles.

Let me know what the fecal results come out as.

Tracie