Hypervitaminosis and vitamin A deficiency in turtles

What is it?

Vitamin A balance is essential for the health of the Greek tortoise (Testudo graeca). This vitamin is involved in vision, protection of the skin and mucous membranes, as well as in the proper functioning of the immune system. \n\nTwo opposing situations pose a problem: deficiency, very common in turtles fed a poor and unbalanced diet, and excess (hypervitaminosis), more rare, which occurs especially after poorly controlled supplementation or repeated injection without veterinary advice. \n\nBoth disorders mainly affect the skin, eyes and mucous membranes, but with different mechanisms and consequences.

Vitamin A deficiency is first manifested by swollen, half-closed or glued eyes with secretions, sometimes accompanied by swelling of the eyelids. \nThe turtle may show progressive loss of appetite, general weakening and greater susceptibility to respiratory or eye infections. \nThe skin may become dry, thickened, with scaly areas or small wounds that heal poorly. \n\nHypervitaminosis A, conversely, mainly causes skin damage: the skin becomes abnormally thin, peels off in shreds, sometimes with red, sensitive or oozing areas. \nIn severe cases, more general disorders such as marked depression or weight loss may appear.

Commonly observed signs

These signs are neither exhaustive nor specific. Only a veterinarian can establish a diagnosis.

Causes and risk factors

The deficiency almost always results from a diet too poor in plants rich in beta-carotene (precursor of vitamin A), replaced by a base too rich in fruits, unsuitable industrial foods or too poor and varied vegetation. \n\nHypervitaminosis typically occurs after excessive vitamin supplementation given by the owner, a repeated injection of vitamin A for “preventive” purposes without veterinary monitoring, or the use of supplements not suitable for reptiles.

Captive turtles fed monotonously, with few green leafy plants or edible wild plants, are most exposed to deficiency. \nLack of exposure to suitable UV light can worsen associated metabolic disorders. \n\nFor hypervitaminosis, the main risk factor is self-medication: “just in case” supplementation without controlled dosage, or repeated vitamin treatments close together.

Diagnosis and care

Diagnosis is the veterinarian's responsibility, based on clinical examination and laboratory tests. Care is decided case by case.

Treatment

Management of the deficiency is based on a gradual correction of the diet, possibly associated with vitamin A supplementation strictly supervised by the veterinarian. \nTopical eye care may be necessary if eye damage occurs. \n\nFor hypervitaminosis, treatment consists above all of immediately stopping all supplementation, supporting skin healing and treating possible superinfections with local care or an antibiotic if necessary.

Prevention

Possible complications

Untreated deficiency can progress to severe eye infections, respiratory tract damage, or even partial vision loss. \n\nSevere hypervitaminosis can lead to extensive skin peeling, secondary bacterial infections of the skin and a significant general weakening of the animal.

When to see a veterinarian

Prognosis

The prognosis is generally favorable for the deficiency if it is taken care of early and if the diet is corrected sustainably. \n\nFor hypervitaminosis, the prognosis depends on the severity of the skin lesions at the time of diagnosis; Early treatment significantly improves the chances of complete recovery.

Frequently asked questions

References

AVMA — American Veterinary Medical Association

Cornell Feline Health Center

Content reviewed by the TunisieVet editorial team · Updated 29 August 2026