Tortoises live long lives, growing much slower than other animals.
Depending on the species, a tortoise may take up to a decade to reach its full size. However, there are times when a tortoise’s growth might slow down or stall, seemingly without explanation.
Fortunately, most cases of stunted growth in tortoises can be corrected by adjusting their habitat, diet, and enrichment. These changes will mean the tortoise can grow and catch up on any lost size.
Some situations will cause a tortoise to grow slowly or stop growing entirely. Some are caused by genetics, while others are caused by habitat or lifestyle. The causes are as follows:
1/ Cramped Enclosures
Therefore, captive tortoises living in too-small enclosures with little room for walking and climbing will likely experience a slower growth rate than those with greater freedom.
2/ Genetic Factors
Species, such as Kleinmann’s tortoise and the speckled cape tortoise, are naturally small due to their genetic makeup. So, any growth is likely to go unnoticed and be mistaken for stunted growth.
Some tortoises experience growth impediments due to genetic flaws passed on from previous generations. Unfortunately, there’s no way to address the problem if this is the case.
3/ Unmet Metabolic Needs
Inadequate exposure to sunlight can impede the absorption of vitamin D3 and calcium, which are essential for bone, shell, and skeletal formation.
For this reason, captive tortoises must have a basking area in their outdoor enclosure and UV lights when kept indoors. This can help tortoises grow at a normal pace or prevent stunted growth.
4/ Inadequate Diet
Most tortoises are herbivores, so they mainly subsist on plants and vegetation.
Of course, they’ll consume most non-toxic weeds, herbs, and leafy greens. However, the bulk of their diet should comprise fiber-rich and low-protein foods.
Provide nutritional supplements to ensure they receive other nutrients that they may not be getting from their regular diet. For example, calcium supplements promote healthy bones and shell growth.
According to The Veterinary Record, tortoises that receive sufficient calcium in their diet have the highest growth rate and better overall health.
5/ Early Skeletal Damage
Stunted growth in tortoises often arises due to injuries in their formative years.
Young tortoises are more vulnerable to skeletal or shell damage. When this happens, the normal growth of tortoises can stall, causing them to remain small.
So, if a tortoise had a fall at a young age, this may explain why it doesn’t grow to the same size as others. This can be true even if the tortoise appears to have fully recovered from its injury.
6/ Internal Parasites
According to Parasitology Research, internal parasites are common in tortoise species.
The most prevalent are ascarids, such as roundworms and pinworms; protozoans, like cryptosporidium; flukes, and amoeba. So, it’s important to check for worms in tortoises’ feces.
While not all parasites are dangerous for tortoises (some are entirely natural), most attack the gastrointestinal organs of their host, depriving them of the nutrients they need to grow.
Stress can cause a tortoise to stop growing properly, so its enclosure must be peaceful and relaxed. So, avoid loud noises, bright lights, sudden activity, and other animals (including pet cats and dogs).
Tortoises are loners, so they’re unlikely to appreciate another tortoise’s company, especially one from a different species or a second male. Tortoises only usually come together to breed.
Also, ensure that the tortoise has plenty to do, as a tortoise will become stressed without enrichment. Add climbing structures, foraging toys, digging materials, and hides to the tortoise’s enclosure.
8/ Sub-optimal Temperature And Humidity
Tortoises require a warm, humid enclosure to be healthy and grow. If the ambient temperature is too cold or too hot, it can lead to stunted growth.
Optimal temperatures for tortoises are species-specific, but 70-85°F (21-29°C) is usually optimal. Also, the humidity level should be 50-80%.
If the temperature is too low, tortoises become inactive, slowing their growth. Also, tortoises become stressed and dehydrated if the temperature gets too hot, resulting in stunted growth.
How To Tell If A Tortoise Is Not Growing
Identifying stunted growth in a tortoise isn’t always easy, especially with small species. That’s further compounded by the fact that most tortoises grow at such a slow rate.
There are two ways to track the growth of a tortoise. Measuring and weighing the tortoise every few months will determine whether it’s steadily increasing in size.
Alternatively, you can trace an outline of the tortoise on a piece of paper every few months. Then, you can compare the drawn outlines to determine if they’re getting bigger.
The growth rate of individual tortoises varies based on their species, diet, and living environment. A tortoise’s shell will grow with them.
Usually, captive tortoises grow faster than wild varieties due to the over-consumption of high-protein foods. Protein usually accounts for under 15% of a wild tortoise’s diet.
Although tortoises should consume some protein, it isn’t advisable to feed them protein-rich foods regularly or in large amounts.
Excessive protein leads to rapid shell growth, but the shell composition is less dense. Unfortunately, this can lead to irreversible shell conditions, such as shell pyramiding.
Most slow or stunted growth cases occur due to unsuitable living conditions and dietary issues.
Unless the tortoise has a genetic condition that prevents it from growing properly, there are ways to promote faster growth. These include the following:
For tortoises to grow, they need enough space to roam freely, dig and burrow, and climb surfaces.
Housing a tortoise in a large enclosure with lots of room allows it to remain active and improves its gut motility, assisting with the absorption of nutrients.
Tortoises require UVB light to facilitate healthy bone and shell growth.
Although wild tortoises usually bask in the sun during the day to meet their UVB light needs, they must be provided with artificial UV-emitting bulbs in captivity.
Providing a nutrient-rich diet is among the most important things you can do to ensure the tortoise grows healthily and to its optimal size.
Tortoises need a diet rich in calcium, phosphorus, magnesium, zinc, and Vitamins A and D. The best foods for tortoises include non-toxic plants and vegetables like:
- Aloe vera
- Collard greens
- Brussel sprouts
Unless you have a fruit-eating species, like the red-footed or Hermann’s tortoise, fruit consumption should be limited to prevent digestive issues that can inhibit nutrient absorption.
Tortoises are prone to internal parasites, such as worms, mites, and ticks.
Parasites cause damage to the gastrointestinal organs, depriving tortoises of the nutrients they need to grow and thrive. They can adversely affect tortoises’ growth rate and health.