Yellow Fat Disease in Dogs

Yellow fat disease is the common name for a medical condition known as steatitis or pansteatitis. It is a rare condition in dogs and is characterized by an inflammation of the fatty tissue that causes a hardening of the fat reserves, giving them a rubbery texture and yellowed appearance. This condition can become very painful for the animal and cause them to lose interest in eating. A change in diet and supplementation with vitamin E are useful in reversing this condition, and most animals will fully recover with this treatment.

Pansteatitis or steatitis is more commonly known as Yellow Fat Disease. Although this is more frequently related to cats, on rare occasions it can be seen in canines as well.

The symptoms of yellow fat disease can occur at any age, however, it is more common for older dogs to develop this disorder. Signs that your canine has developed this disorder can include:

• Depression
• Fever
• Flaky skin
• Greasy coat
• Joint pain
• Lethargy
• Loss of appetite
• Pain to the touch 
• Reluctance to move
• Subcutaneous lumps

Types

Pansteatitis and panniculitis are two different conditions with very similar properties, however, they may have very different triggers. 

Panniculitis is also an inflammation fatty tissues, but it is restricted to the the fatty tissues that are positioned in the subcutaneous layer. This disorder often accompanies cases of steatitis, however, it can also occur due to trauma, inflamed lipomas, immune disorders, and reactions to injections. 

Pansteatitis is an inflammation of the fatty tissues and can occur in the subcutaneous layer, but it is not restricted to these areas. It also features a hardening and yellowing of the fat which may or may not be present in the inflamed lumps of panniculitis that are found just under the skin. This disorder is most often caused by nutritional imbalances.

The causes of this disorder are poorly understood, however, it is most often attributed to an overabundance of unsaturated fatty acids in the diet, and a deficiency in the amount of vitamin E. Other possible factors in the development of this condition can include:

• Ingestion of affected animals
• Microcystin toxicity
• Poisoning from heavy metals
• Unidentified pathogens

Your visit to the veterinarian’s office is likely to start with a thorough physical examination, and in most cases, the examiner will find that the animal shows signs of pain on being handled. Panniculitis nodules may also be located by palpating the skin of the patient, which is likely to be in poor condition and the dog’s history will also be requested, including a timeline of symptoms and information about their daily diet. The results of standard diagnostic tests, such as a complete blood count, biochemical profile, and urinalysis, will help to determine if any underlying conditions are contributing to the dog’s distress. 

A biopsy will be done on any nodules are found on the skin by taking samples of the underlying tissue utilizing a technique known as fine-needle aspiration. Samples collected from the fat tissue used for biopsy will exhibit the characteristic yellowish brown color, and will generally have inflamed adipose cells. These samples will also be tested to rule out bacterial or fungal infections as well as cancer.

If nodules are found in the subcutaneous tissue, they may require removal and immunosuppressive drugs such as glucocorticoids or anti-inflammatory medications such as NSAIDs may be temporarily prescribed to reduce the pain and inflammation caused by this disease, although anti-inflammatory medications may not be as effective for cases of steatitis. As this disorder is generally caused by a nutritional imbalance, a change in diet is the most effective treatment for this disease in most cases. The corrected diet should be designed to be low in polyunsaturated fats; foods that are high in polyunsaturated fats can include:

• Corn oil
• Fatty fish (herring, mackerel, salmon, trout)
• Flax seeds
• Soybean oil
• Sunflower oil 
• Sunflower seeds
• Walnuts
• Wheat germ

This disorder is also responsive to additional supplementation of vitamin E in the form of a-Tocopherol, which can be administered as an oral medication or by injection. The additional supplementation of vitamin E typically lasts several weeks after the visible symptoms have been eliminated.

The prognosis for this condition is generally quite good once the patient’s diet has been adjusted to fit its nutritional needs, and signs of the disorder are often fully eliminated within just ten weeks of starting treatment. It is essential to continue all medications as instructed by your veterinarian in order to prevent any complications or relapses. The dog should not be returned to its previous diet as this may eventually lead to a reoccurrence of the discolored and swollen tissues. Any wounds caused by trauma to the subcutaneous lesions will need to be assessed, and antibiotic or antifungal drugs may be recommended to help control or prevent the development of bacterial or fungal infections.