Hepatic lipidosis, often called fatty liver disease, is defined as an increase in fat in the liver that is significant enough to cause disease and adversely affects liver function. The most common cause of fatty liver disease is over-feeding in any adult reptile. This disease is especially common in turtles and tortoises.
In the majority of reptiles with fatty liver disease, there is usually a gradual reduction in appetite and activity; they may have reduced weight gain or gradual weight loss; hibernation problems, including post-hibernation lack of appetite; and changes in fecal character and color (diarrhea and light colored feces).
When hepatic lipidosis has been going for a long period of time and is considered chronic, most affected reptiles will be in poor body condition and are flaccid, weak, and extremely thin. Many reptiles with this disease will have abnormal fluid in the abdomen. Regurgitation can occur (especially in turtles and lizards), and is considered to be a poor sign. In chronic cases of hepatic lipidosis, diarrhea is uncommon.
In acute cases where the liver disease has just started, the affected reptiles are usually in good body condition but will have a sudden-onset of lethargy and lack of appetite; they will be great one day and then sick the next. In these acute cases, diarrhea is more commonly seen, and if the urates (the normally white portion of the feces) are pigmented yellow-green, this may indicate severe liver compromise and decrease in function. These severely affected animals usually will be depressed, lethargic, and weak; and their gums may be pale or have a yellowish color to them.
Some of the reasons reptiles become ill with hepatic lipidosis is because the function of the liver becomes compromised. The functions of the reptile liver are similar to those of mammals and birds, including fat and protein metabolism, production of uric acid and blood clotting factors; when these functions are reduced, the animal becomes ill. It is important to remember that hepatic lipidosis is a metabolic derangement and is not a single disease.
Any species of reptile can be affected with fatty liver disease but it appears commonly in turtles and tortoises, large carnivorous lizards (monitors, tegus), and bearded dragons (Pogona vitticeps).
Your veterinarian will start by taking a thorough medical and husbandry history and give a physical examination. Because any disease that results in lack of appetite or metabolic problems, including toxins such as ivermectin in turtles and tortoises, can lead to a fatty liver your veterinarian may need to perform an number of diagnostic tests to find out the cause of the disease. Additionally, hepatic lipidosis must be differentiated from physiologically normal increases in liver fat associated with hibernation and reproduction. These tests may include:
- Blood work
o Acute inflammation or necrosis of the liver usually will result in a dramatic change in the blood cells that can be detected and may be able to diagnose a bacterial or parasitic reason for the liver disease.
o The liver can often be seen on X-rays and your veterinarian may be able to tell if the liver is larger or smaller than normal.
o It is often possible to detect changes in the liver that may suggest a reason for the liver disease that X-rays cannot detect.
- Specific liver tests
o Bile acids are often seen at much higher levels when there is liver disease.
o Endoscopic evaluation of the liver to get samples for testing.
o MRI provides excellent soft tissue detail of the liver and may be indicated in some cases.
Because these reptiles are often dehydrated from being ill, your veterinarian may give fluids and nutritional support to stabilize them. In mild to moderate cases of hepatic lipidosis, oral fluids may adequate but in cases with more severe disease, reptiles often require intravenous (IV) or intraosseous (in the bone) administration. Based on the results of all these tests, your veterinarian may prescribe antibiotics for the treatment of the disease.
In chronic cases of hepatic lipidosis, it is important to understand that treatment may take months, if not years, to reverse. Therefore, means of providing long-term fluid and nutritional support may be needed; the importance of nutritional support cannot be overemphasized.
Your veterinarian will discuss the different ways to provide this fluid and nutritional support, which may include tub feeding or the placement of a feeding tube that take into account the patient’s energy and nutritional requirements as well as the patient’s natural dietary preferences (e.g., herbivorous, omnivorous, carnivorous).
It is critical that the suggestions by your veterinarian to modify and monitor weight and food intake be followed. Some things that your veterinarian may suggest are the repeat monitoring of the reptile’s liver enzymes and bile acids and performing serial liver ultrasound and endoscopic liver biopsies for histopathology at 3, 6, and 12 months to look at the progression of healing.
Appropriate husbandry is critical (temperature, diet, exercise) in preventing hepatic lipidosis; specifically, dietary requirements for the specific reptile species in question. Overfeeding is the single most important risk factor for developing hepatic lipidosis in reptiles, but especially in species that are prone to overeating and obesity (see above). Additionally, larger enclosures or the opportunity to exercise these is quite important.
Consider and discuss with your veterinarian spaying as a preventive procedure for conditions such as reproductive disease and hepatic lipidosis, especially in female lizards, turtles and tortoises.
Prognosis and Outcome
Unfortunately, the prognosis for severe chronic hepatic lipidosis is guarded to poor, but for acute cases given proper treatment, husbandry and dietary changes the prognosis is much better.