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do tortoises need calcium?

How To Give Tortoises Calcium

Last Updated on October 10, 2023 by Samantha Harris

Tortoises need calcium carbonate and vitamin D3 (from the sun’s rays or artificial UV lighting) for strong bones, healthy shells, muscle and nerve function, hormone production, and metabolism.

Tortoises are at risk of Metabolic Bone Disease (MBD), brittle bones, lethargy, twitching, tremors, and seizures without sufficient calcium. Females need extra calcium for egg development.

While lacking a nutrient like calcium is bad, an overabundance can be almost as damaging. If a tortoise gets too much calcium, it’s at risk of arterial sclerosis (hardening of the arteries).

Why Do Tortoises Need Calcium?

The tortoises’ physiology relies on calcium to grow and function healthily.

Besides their bone structure, tortoises need calcium because their shell comprises beta-keratin, and calcium determines how thick and robust it’ll be.

Without enough calcium, a tortoise’s shell will become soft, deformed, or may not even grow.

Females need more calcium when developing and laying eggs. Since calcium goes into forming and passing eggs, hypocalcemia will result in health problems for the female and her clutch.

tortoise calcium deficiency symptoms

Can a Tortoise Have Too Much Calcium?

A tortoise can have too much calcium, but this is rarely acknowledged.

Hypercalcemia can result in the calcification of certain body parts. Calcification occurs when calcium builds up in soft tissues, organs, and blood cells.

A significant calcium buildup can cause pain, depending on where it has accumulated. As calcium passes through urine, it’s hard for a tortoise to build up large calcium deposits quickly.

According to the Veterinary Record, tortoises that ingest excessive calcium fare better than those that ingest too little. However, they have the highest rate of metastatic calcifications.

Tortoises that get too much dietary calcium are far more at risk of developing kidney stones. A vet can confirm if there’s excess calcium in the tortoise’s urine and blood.

How Do Tortoises Get Calcium in the Wild?

Tortoises can get calcium from various sources, including vegetation like dandelions.

Plants such as kale, common in areas where tortoises are native, contain a good amount of calcium for tortoises. Fruits and berries (like kiwi, figs, and oranges) are other viable sources.

Snails with crunchy shells made of calcium carbonate and protein are another option.

Egg shells are harder to come by, but tortoises eat them for their calcium content. There are instances where females eat their eggs when they’re low on nutrients like calcium.

Tortoise Calcium Deficiency Symptoms

A calcium deficiency (hypocalcemia) affects a tortoise’s happiness level, the shape and growth of its shell, and skeletal development.

Health problems related to a tortoise’s bones and shell are called Metabolic Bone Disease (MBD). The most common symptoms of MDB in tortoises are:

  • Soft shells.
  • Deformed shells.
  • Lethargy.
  • Small shell in comparison to the body.
  • Pyramiding.
  • Egg binding.
  • Trouble walking.
  • Bone fractures.
  • Loss of appetite.
  • Constipation.
  • Bowed legs.
  • Shell breakage.

Other issues resulting from calcium deficiency include respiratory infections and tortoise cloacal prolapse. An unbalanced diet affects the immune system, so you may hear it wheezing.

A lack or overabundance of calcium can cause kidney stones. When a tortoise is trying to pass a bladder stone through its cloaca, some of its organs may exit the body cavity along with the stone.

how do tortoises get calcium in the wild?

How To Give Tortoises Calcium

You can offer a tortoise calcium-rich foods or give it a cuttlebone or mineral block.

Cuttlebone is made of 85% calcium carbonate. Many tortoise owners prefer giving their pets cuttlebones because it also helps keep their beaks trimmed.

Tortoise Food with Calcium

Many fruits and vegetables are rich in calcium, including the following:

FoodCalcium Per 100 Grams
Collard Greens141 mg
Parsley138 mg
Turnip Greens137 mg
Spinach136 mg
Kale132 mg
Beet Greens114 mg
Oranges40 mg
Mulberries39 mg
Tangerines37 mg
Kiwi34 mg
Blackberries29 mg
Papaya20 mg
Guava18 mg

If you’re giving a tortoise calcium-rich foods, limit the calcium supplements it gets if it isn’t very active (elderly tortoise, wintertime inactivity, etc.)

Some people believe tortoises regulate their need for calcium and only consume as much as they need. However, their instincts may compel them to gorge on food and gain weight.

How Much Calcium Should A Tortoise Have in Its Diet?

The amount of calcium a tortoise requires is age, gender, and species-specific. For example, a young gravid female tortoise needs more calcium than a senior male tortoise.

Ensure that 1% of all dry matter is calcium and that the phosphorous ratio is 2:1.

It’s broadly accepted that too much calcium is better than too little calcium. The reverse applies to nutrients like protein, often leading to abnormal growth and development.

For chelonians to absorb calcium, they need sufficient vitamin D3. This means a tortoise must be exposed to the sun’s UV rays or have a specific artificial lighting setup in its enclosure.

Without sufficient vitamin D3, calcium supplementation won’t keep tortoises healthy.