Should I trust the Jackson Ratio?

Mweigel

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So my hermans tortoise Poe acts fine, she eats most of her food, greens, and some small Mazuri pellets. She walks around her enclosure and makes a huge mess, her eyes are clear and she is really responsive. She weighs 741g and is 7 3/4in top to bottom and side to side. I put the information in the Jackson ratio and it says she is super underweight. I'm not sure what to do about it. Since I got her in 2019 she has grown 2in and has gained over 450g. I don't know how old she is it's estimated she's almost 7. I haven't planned on hibernating her so I'm not sure if I should look at the ratio anymore. Suggestions would be helpful
 

Markw84

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I believe you must be measuring your tortoise improperly. I have no idea what you mean by "top to bottom and side to side" Are you adding the length AND width of your tortoise? That would be your problem.

The Jackson ratio is a decent guideline for most Testudo, and anything way out of the recommended range should be of concern.

You need to use the SCL - Straight Carapace Length in centimeters. So put your tortoise on a flat surface with the front of the shell touching a wall or some straight vertical surface. Draw a line exactly at the back edge of the shell where it covers the tail area. Measure that distance in cm. OR... simply place your tortoise with the front edge touching a flat vertical surface with the tortoise on top of a ruler in cm. that is also touching the vertical surface with the zero end. Read the length at the rear of your tortoise looking straight down.

You would then use that SCL in cm and the weight in grams to plug into the jackson ratio calculator.
 

Mweigel

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I believe you must be measuring your tortoise improperly. I have no idea what you mean by "top to bottom and side to side" Are you adding the length AND width of your tortoise? That would be your problem.

The Jackson ratio is a decent guideline for most Testudo, and anything way out of the recommended range should be of concern.

You need to use the SCL - Straight Carapace Length in centimeters. So put your tortoise on a flat surface with the front of the shell touching a wall or some straight vertical surface. Draw a line exactly at the back edge of the shell where it covers the tail area. Measure that distance in cm. OR... simply place your tortoise with the front edge touching a flat vertical surface with the tortoise on top of a ruler in cm. that is also touching the vertical surface with the zero end. Read the length at the rear of your tortoise looking straight down.

You would then use that SCL in cm and the weight in grams to plug into the jackson ratio calculator.
So the top near the head of the shell to the bottom is 7 3/4". oh so maybe I am measuring wrong. I haven't measured against the wall, I have used a fabric tape measure to measure her from top to bottom. Thank you I will do that
 

Markw84

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So the top near the head of the shell to the bottom is 7 3/4". oh so maybe I am measuring wrong. I haven't measured against the wall, I have used a fabric tape measure to measure her from top to bottom. Thank you I will do that
Yes, you are measuring the curved (over the shell) carapace length. You want straight carapace length. That will make a difference!
 

Yvonne G

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So the top near the head of the shell to the bottom is 7 3/4". oh so maybe I am measuring wrong. I haven't measured against the wall, I have used a fabric tape measure to measure her from top to bottom. Thank you I will do that
Not over the curve. . . in a straight line.
 

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