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Concern over Ghost's weight

Discussion in 'Sulcata tortoises' started by Mizcreant, Jan 11, 2019.

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  1. Mizcreant

    Mizcreant Well-Known Member Tortoise Club

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    Based on the tBMI formula (tBMI= cWTcm/tWTgr), I'm a little concerned with Ghost's weight and am looking for suggestions.

    His current diet consists of a variety/combination of greens including weeds, dandelion greens, bok choy, turnip and mustard greens, and escarole. I will throw in maybe 8-10 pellets of Mazuri Diet per day as well. He gets fed in the mornings, and I might occasionally throw in a small amount of greens or Mazuri at night after his soaks if he appears hungry and had polished off his bowl from the morning.

    Here is his weight chart (cWTgr):

    upload_2019-1-11_19-17-55.png

    Here is his growth (SCLcm) progress:
    6/24/2018 4.3cm
    7/15/2018 6.4cm
    8/12/2018 8.6cm
    9/9/2018 8.9cm
    10/7/2018 10.3cm
    11/4/2018 11.7cm
    12/9/2018 13.0cm
    1/6/2019 14.6cm

    And finally, here is his tBMI chart:
    upload_2019-1-11_19-25-43.png

    My goal is to try to get his tBMI as close to the 1.0 point as possible. As it stands (according to the chart), he is overweight. Any recommendations what I could be doing to achieve this? Thanks in advance!
  2. Yvonne G

    Yvonne G Old Timer TFO Admin

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    Sorry, it's all greek to me!
  3. Mizcreant

    Mizcreant Well-Known Member Tortoise Club

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    I'm sorry. Here's the index I'm going by:

    - 0.66 or lower: There is less than a 2.5% chance that this tortoise is healthy at this weight. It is probably very dehydrated and/or underfed and should be seen by a vet.
    - 0.66 to 0.83: There is only about a 15% chance that this tortoise is healthy at this weight. It is probably dehydrated and/or underfed and needs appropriate care.
    - 0.83 to 1.00: This is a normal range, but statistically a little underweight, which may signal mild dehydration and/or being underfed. Review and correct cares and diet as appropriate.
    - 1.00 to 1.16: This is a normal range, but statistically a little overweight, which may signal mild overfeeding. Review and correct cares and diet as appropriate.
    -1.16 to 1.33: There is only about a 15% chance that this tortoise is healthy at this weight. It is probably at least somewhat obese and needs appropriate care.
    1.33 or over: There is less than a 2.5% chance that this tortoise is healthy at this weight. It is probably obese and needs appropriate care.

    As you can see, the 1.00 mark is optimum which is where I'm trying to get.
  4. Big Charlie

    Big Charlie Well-Known Member

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    I didn't know you could overfeed a tortoise. I'd be more worried if he wasn't gaining weight. Who devised this index?
    If you want to slow the weight gain, cut out the mazuri and make sure he gets a lot of exercise.
    Do you weigh him before or after soaks?
  5. Mizcreant

    Mizcreant Well-Known Member Tortoise Club

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    I was going by Madkins007's post from back in 2008 on determining BMI and hydration. Here's the post and link:

    https://www.tortoiseforum.org/threads/tortoise-weight-formula-tbmi.38420/

    Susan Donoghue, DVM wrote an article about tortoise weights in 1997- "Nutritional status of tortoises using morphometrics to assess body condition".Vivarium magazine, Volume 8 Number 2, in which she offers is the helpful formula "SCLcm^3 x 0.191 = tWTgr", where SCLcm is 'Straight-line carapace length in centimeters' and tWTgr is 'Target weight in grams'. (See the end of the article for advice on getting a good SCL).

    The data is based on 76 tortoises and box turtles representing 11 species, and works fairly well even for young tortoises.

    We are going to make this formula more 'user friendly' by using it to calculate the tortoise's Body Mass Index, the BMI that all dieters are familiar with. Because this is tailored for torts, we are going to call it the tBMI.

    tBMI= cWTcm/tWTgr
    (or SCLcm^3 x 0.191)[/b]

    EXAMPLE:
    A tortoise with a straight-line carapace length (SCL) of 12.3 centimeters and a cWTgr (current weight in grams) of 349.
    - The tWTgr is 355.425597 (12.3^3x0.191)
    - 349/355.4= 0.982
    - tBMI= 0.982

    (Note- Google do all the work for you if you type in "[current weight in grams]/([SCL in centimeters]^3x0.191)=". The answer you get will be the tBMI.)

    RESULTS:
    You can determine if your tortoise is normal, dehydrated, or obese based on these results. Note- the figures used below are extrapolated from several sources and should be used as guidelines only!

    - 0.66 or lower: There is less than a 2.5% chance that this tortoise is healthy at this weight. It is probably very dehydrated and/or underfed and should be seen by a vet.
    - 0.66 to 0.83: There is only about a 15% chance that this tortoise is healthy at this weight. It is probably dehydrated and/or underfed and needs appropriate care.
    - 0.83 to 1.00: This is a normal range, but statistically a little underweight, which may signal mild dehydration and/or being underfed. Review and correct cares and diet as appropriate.
    - 1.00 to 1.16: This is a normal range, but statistically a little overweight, which may signal mild overfeeding. Review and correct cares and diet as appropriate.
    -1.16 to 1.33: There is only about a 15% chance that this tortoise is healthy at this weight. It is probably at least somewhat obese and needs appropriate care.
    1.33 or over: There is less than a 2.5% chance that this tortoise is healthy at this weight. It is probably obese and needs appropriate care.

    RESOURCES:
    - http://www.tortoiselibrary.com/ for articles on hydration/dehydration, a bibliography, and more
    - BARTHEL, Tom “The Hydration Equation” Reptiles, July 2007
    - DONOGHUE, Susan,1997. "Nutritional status of tortoises using morphometrics to assess body condition".Vivarium magazine, Volume 8 Number 2
    - MADER, Douglas R., DVM, ed. "Reptile Medicine and Surgery". Saunders Elsevier, 2nd Edition 2006.

    APPENDIX: Getting a good SCL reading.
    The easiest way to get a good SCL without tools like calipers is to...
    1. Place a metric ruler on the floor, '0' against the wall.
    2. Set the tortoise on the ruler, head towards the wall, and position it so the shell touches the wall.
    3. Place a block, box, etc. behind the tortoise, on the ruler, and move it so it touches the back of the tortoise's shell.
    4. Move the tortoise and read the ruler at the block.

    (Note- if the ruler has a space beside the '0' mark, you should either cut the ruler down so '0' is on the end, or remember to subtract the size of the gap from the final measurement... or cut the end off so '0' in on the end!)
    Madkins007, Dec 27, 2011
  6. Big Charlie

    Big Charlie Well-Known Member

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    Honestly, I think there are other factors that this index doesn't take into account. BMI doesn't take into account bone density or muscle mass, as well as other factors. With tortoises, some have a higher dome, which would lead me to believe that their weight would be greater compared to their length than other tortoises. What about pancake tortoises? How can you hold them to the same standard?
    TechnoCheese and Mizcreant like this.
  7. Mizcreant

    Mizcreant Well-Known Member Tortoise Club

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    That is certainly a thought. So you think I should scrutinize the formula a bit more before accepting it as gospel?
  8. Big Charlie

    Big Charlie Well-Known Member

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    I do. I think you can go too far in analyzing every little thing. When I got Charlie nearly 20 years ago, it never occurred to me to track his growth. I've never weighed him. I'm curious but I can tell he is healthy by the way he acts.
    SulcatAZer likes this.
  9. jsheffield

    jsheffield Well-Known Member Platinum Tortoise Club

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    I had some concern that in feeding my redfoot Darwin nearly everyday I was running the risk of killing him with kindness (or at least chancing some form of uneven growth).

    I ran his numbers through the tbmi formula, and it yielded a 0.96.

    Although I know the formula isn't designed for hatchlings, this result quieted my worries, and I'll likely continue on with feeding/soaking him him along the same lines that I've followed until now.

    Jamie
  10. Mizcreant

    Mizcreant Well-Known Member Tortoise Club

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    Nice. I've altered Ghost's diet slightly. He isn't getting as much exercise due to it being winter. Think he'd do good on a hamster wheel?[​IMG]
    Cheryl Hills, Miscally and jsheffield like this.
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