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(This information is meant only to inform and educate you, it does not replace Veterinary treatment.  Always take your pet to your Vet for a proper diagnosis of a health problem)

What Is Protein-Losing Enteropathy?

Protein-losing enteropathy is a fancy way of saying that protein is being lost from the body through the intestine. This is a serious problem as the body's proteins are not easily replaced and the only way to replace them involves the absorption of protein constituents (the amino acids that make up proteins) from the intestine. If the intestine is actually leaking nutrients out instead of absorbing them in, the result is a nutritional disaster. Protein Losing Enteropathy is an inherited immune-mediated disease of the intestines. Many dogs don't show clinical signs of this disease until they are over the age of 5. Abnormal fluid accumulation may occur secondary to decreased protein levels in the blood.

The mechanism for protein loss in protein-losing enteropathy may be related to inflammation or erosion affecting the normal barrier function of the gut, or to acquired or congenital abnormalities in intestinal lymphatic or vascular drainage. The most important protein-losing gastroenteropathies are associated with chronic inflammatory diseases and circulatory diseases such as impaired drainage of lymph glands of the digestive tract. When loss of plasma proteins is by protein-losing enteropathy due to inflammation, there are often associated clinical signs of gastrointestinal disease such as vomiting, loss of appetite or diarrhea that suggest an underlying problem in the gastrointestinal tract.   Protein-losing enteropathy is one mechanism contributing to weight loss in gastrointestinal disease. In some cases there is severe loss of proteins such that the body can not maintain proper plasma protein concentrations. This may be so sever that fluid will accumulate in the abdominal cavity or chest.

The main protein that one cannot afford to lose is called albumin. This protein normally is produced by one's liver and circulates in the bloodstream acting as a carrier for biochemicals that require transport but cannot actually dissolve in blood. Albumin can be considered sort of a mass transit system in the bloodstream, a bus or subway, if you will, carrying important biochemicals from one place to another.  Albumin, by being the most prevalent blood protein, also is responsible for actually keeping water in one's bloodstream. When water cannot be held within the vasculature, it leaks out causing fluid accumulation in tissue (i.e., edema) or in within the chest or abdomen (i.e., effusion).

Of course, in a protein-losing enteropathy, other proteins are lost, too. Antibodies, proteins of blood clotting, enzymes, etc. all leak out the intestine and are forever lost in the feces that exit the body.  The body tries hard to maintain its albumin level by extracting protein from other sources (like muscle), and having the liver make albumin from the components of these other proteins. This may help maintain a workable amount of albumin in the bloodstream but it comes at the expense of muscle tissue and other protein.

Clinical Signs

Animals with protein-losing enteropathies usually exhibit signs of weight loss (muscle wasting and decreased body fat). There may be vomiting and diarrhea and fluid accumulation in the abdomen can create a bloated appearance, but these signs are by no means always seen, and it should be emphasized that failure to exhibit diarrhea or other characteristic signs of gastrointestinal disease does not eliminate the possibility of protein-losing enteropathy.

Signs related to the underlying disease responsible for protein-losing enteropathy may be present, and physical examination may reveal evidence of thickened bowel loops, an abdorninal mass, or cardiac abnormalities. If hypoalbuminemia is severe then this may be responsible for the sole presenting signs (swelling of the limbs,fluid accumulation in the abdominal cavity, or difficult breathing due to fluid accumulation in the chest cavity). Limb swelling and fluid accumulation in the abdomen are generally present when the serum albumin concentration decreases.

How is A Diagnosis Made?

In most cases, an obviously sick dog is brought to the veterinarian. Sometimes the above classical signs are present but sometimes there is no specific hint of this condition until blood test results are in.

Low lymphocyte count: Animals with lymphangiectasia have lymphocytes rolling out their lacteals and into their intestine. The low blood lymphocyte count is so consistent with lymphangiectasia that it is difficult to make this diagnosis if this finding is not present.
Low cholesterol: Cholesterol is part of the lymph fluid being lost.
Low albumin level: Low blood albumin level is the most consistent finding in lymphangiectasia, though it is possible to have lymphangiectasia in a small portion of the intestine only and still maintain a normal albumin level. There are only four ways a patient can develop a low albumin level.
A protein-losing enteropathy
Glomerular disease (such as glomerulonephritis) in which albumin is lost through diseased kidneys
Reduced albumin production in the liver due to liver failure
Serum leakage through extreme skin damage (such as third degree burns)
These conditions can be easily ruled out one by one. It is obvious if third degree burns are present. If there are none, a routine urinalysis will indicate if there is significant protein loss in the urine and if glomerular disease should be pursued. A liver function test such as a bile acids test will indicate whether or not there is liver failure. If none of these three conditions are present, then there must be a protein-losing enteropathy.


Treatment and What to Expect

The first step in treatment is to address the underlying cause. In most cases of lymphangiectasia, the underlying cause involves inflammation and most treatment of lymphangiectasia involves suppression of inflammation.

Medications such as prednisone and/or azathioprineare commonly used, especially if inflammatory bowel diseaseis present.

The second step in treatment is dietary though success has been mixed. Traditionally, rather nasty-tasting medium chain triglycerides have been used in lymphangiectasia treatment. Triglycerides (a fancy word for fats) are very long molecules. Some are longer than others. The more usual dietary fats are called long chain triglycerides and, when absorbed into one's body, must be repackaged into fat globules called chylomicra, and are normally absorbed into the lymph vessels. In lymphangiectasia, we want to reduce the pressure in the lymph vessels. We want less lymph. The idea was that if the patient ate shorter fat chains, the fats could be absorbed right into bloodstream directly and bypass the lymph system altogether. Whether or not this actually happens is still a matter of controversy but adding medium chain triglycerides (or MCTs) in conjunction with a low fat diet are common recommendations in the therapy of lymphangiectasia.

Other treatments include the use of diuretics (such as furosemide to help increase urination and ultimately reduce fluid accumulation in the chest or abdomen. Actual tapping of the body cavity and suctioning the fluid affected may be needed periodically.

If the underlying condition is treatable then prognosis for lymphangiectasia is good. It should be understood that lymphangiectasia is unlikely to be cured and at best can be managed.