Common Diseases of Tortoises

What are some of the common diseases of pet tortoises?

Common conditions of pet tortoises include metabolic bone disease (MBD), pyramiding, vitamin A deficiency, respiratory diseases, abscesses, shell infections, shell trauma, cloacoliths, and parasites.

What are the signs of these diseases?

Metabolic bone disease (MBD) is an imbalance of calcium and phosphorus due to an improper diet, lack of adequate ultraviolet (UV) light, inadequate intake of protein, or a combination of poor diet and insufficient UV light. Signs of MBD in tortoises are usually either a misshapen shell or deformed bones in 1 or all 4 legs. Tortoises affected by MBD grow slowly and often never grow to full adult size. In severe cases, one or more legs will have pathologic fractures from weakened bones. The shell will often be flimsy or pliable beyond the first 6 months of age. 

Fig. 1: A tortoise showing pyramiding, with pyramid-shaped scutes on the upper shell.A condition called pyramiding (Fig. 1) occurs when the upper shell, called the carapace, has raised scutes (the individual sections that form the upper shell and lower shell) that look like pyramids. Although this condition is not completely understood, it has been shown to occur commonly in young tortoises when the environmental temperature and humidity are not optimal or when there is an imbalance in calcium, phosphorus, and/or protein intake.

Vitamin A deficiency (hypovitaminosis A) occurs when a tortoise is fed an inappropriate diet. Tortoises that are fed iceberg lettuce, a high-meat diet, or a poor-quality commercial diet are most likely to develop hypovitaminosis A. Lack of vitamin A produces changes in the epidermis (outer layer of the skin) and in the mucus-producing glands and membranes lining the mouth, eyes, kidneys, and upper respiratory tract. Symptoms include a lack of appetite, lethargy, swelling of the eyelids (often with a pus-like discharge), swelling of the ear (due to the formation of an ear abscess), respiratory infections, and kidney failure in later stages.

In tortoises, most respiratory tract infections are generally caused by either mycoplasma (a type of bacteria) or a bacterial infection secondary to a viral infection. The most common viral infections in tortoises are caused by either Herpesvirus or Ranavirus. Respiratory infections may also be secondary to vitamin A deficiency. Tortoises with respiratory infections may have excess mucus in their mouths (seen as bubbles in the mouth, nose, and eyes), nasal discharge, lethargy, loss of appetite, wheezing, extension of the neck to breathe, and open-mouth breathing or gasping.

Abscesses (infected, pus-filled swellings within a tissue of the body) appear as hard, tumor-like swellings anywhere on the skin or within the pet's body. Reptile pus is usually very thick and dry, with the texture and consistency of cottage cheese. Abscesses may develop in a tortoise’s ears or oral cavity, and they appear as large swellings on the sides of the head, just behind the eyes or in the roof of the mouth. Abscesses in tortoises are often related to vitamin A deficiency. Abscesses in the oral cavity generally cause a thick nasal discharge and/or mucus to form around the sides of the mouth.

Shell infections, called shell rot or SCUD, may be caused by bacteria, fungi, or parasites. These infections are often secondary to trauma, burns, or bites. SCUD is an older term that is defined as Septicemic Cutaneous Ulcerative Disease. Some of these infections can penetrate deep into the layers of the shell, causing ulcers or pitting of the shell or extension into the bone below. Deep ulcerations may become life-threatening if not treated aggressively. The outer (keratin) layer of the shell protects the living bone underneath. The shell is an extremely important form of protection for the inner organs, which are located beneath the shell. 

Shell trauma is somewhat common in pet tortoises. This injury is most often related to a pet dog in the house. When left unattended, dogs like to chew on the shell and can cause puncture wounds or break off large sections of the shell – in some cases, exposing internal organs. Since the shell is a keratinized covering of the bony skeleton, any damage can lead to life-threatening bone infection if not treated quickly and aggressively. Bite wounds from other tortoises usually cause traumatic injuries on the neck or feet.

Fig. 2: A tortoise and cloacoliths, which can cause a blockage of the cloaca.Cloacoliths (Fig. 2) are an accumulation of urates, the crystalline portion of the urine. Large cloacoliths will cause a blockage of the cloaca, which is the port where intestinal and urinary tract excretions exit the body. Tortoises with this condition may be seen straining to produce a bowel movement and will often be heard vocalizing as they are straining. This is a true emergency condition.

Gastrointestinal parasites, such as roundworms and flagellated protozoa, are common in pet tortoises. In many cases, parasitic infections do not cause any clinical signs. They are detected on a routine fecal examination by your veterinarian. With severe infection, parasites may cause diarrhea or weight loss and may require treatment.

How can I tell if my tortoise is sick?

Signs of disease in tortoises may be specific to certain diseases, such as nasal discharge in the case of a respiratory infection, but more commonly, signs of illness are non-specific, such as a tortoise with a lack of appetite and lethargy, which can be seen with many diseases. Any tortoise that shows a deviation from normal should be evaluated by a veterinarian familiar with reptile diseases.

How are tortoise diseases treated?

Tortoises with pyramiding or signs of MBD will require dietary changes and environmental modifications to change the nutritional imbalances and/or improper temperature and humidity settings. Shell and skeletal imperfections may take months to years to correct. Each species has different temperature and humidity ranges that are required for proper shell and bone growth. Severe cases of MBD may leave the tortoise with misshapen bones or a permanent shell deformity.

Fig. 3: A tortoise with pyramiding requires dietary and environmental changes to address the condition.Vitamin A deficiency is treated with either oral or injectable vitamin A. Vitamin A deficiency typically indicates improper nutrition that must be corrected; your veterinarian will make these recommendations. Treatment should only be performed under veterinary supervision, as overdose of vitamin A to treat hypovitaminosis A can occur.

Respiratory infections are most often caused by bacteria. Many tortoises with respiratory tract infections may also have underlying vitamin A deficiency that requires correction. Your veterinarian may recommend taking radiographs (X-rays) and running blood tests and cultures to determine the cause of the infection. 

Treatment of respiratory tract infections usually involves administration of antibiotics orally, through injection, or possibly as nose drops. Very sick tortoises may require hospitalization for intensive care, including injectable fluid therapy, antibiotic injections, and force-feeding. Tortoises infected with either Herpesvirus or Ranavirus often do not recover.

Abscesses are treated surgically. The abscess is opened, pus is drained or surgically removed, and the affected tissue is flushed with a medicated cleansing solution. A culture of the abscess is typically recommended to determine the type of bacteria that is causing the abscess. Topical medication, plus oral or injectable antibiotics, may also be required.

Veterinarians can often repair most basic shell fractures if the fractures are fresh and the patient is in a good nutritional state. Shell infections can be challenging to treat but usually involve microscopic analysis and culture to identify what type of organism (virus, bacteria, or fungus) is causing the problem, thoroughly cleaning the shell, and treating with appropriate medications.

Tortoises with cloacoliths require sedation, medication for pain relief and use of forceps to break down the blockage and flush it out of the cloaca.

Gastrointestinal parasites are treated with deworming medications. The type of parasite identified on a microscopic analysis of the stool will determine which drug is needed.

Photos in this handout courtesy of Dr. Gregory Rich, DVM.