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Intestinal Lymphangiectasia in the Yorkie
Protein-Losing Enteropathies
Protein-Losing Nephropathy
Protein-Losing diseases can occur in two forms: Protein-Losing Nephropathy (PLN) which affects the kidneys and Protein-Losing Enteropathy (PLE) which affects the intestines. Research is showing that PLE and PLN are closely associated and may occur together. PLE is currently the most common type. Both diseases cause the loss of large amounts of protein, in the urine (PLN), and in the feces (PLE).
As part of the normal circulatory system, lymph fluid is collected from tissues throughout the body and returned to the blood by way of the lymphatic vessels. In intestinal lymphangiectasia, normal drainage is blocked so that intestinal lymph leaks into the intestines instead of being returned to the circulation. This results in the loss of proteins, lymphocytes (a type of white blood cell), and lipids or fats into the stool.
Signs of intestinal lymphangiectasia usually develop slowly over several months, and may come and go. Your dog may fail to gain weight or may progressively lose weight. The loss of protein into the bowel causes loss of fluid from the circulation into the limbs, the abdomen, or the chest. Your dog's legs and/or abdomen may appear swollen and he/she may have trouble breathing because of fluid buildup. There may be a chronic persistent or intermittent diarrhea due to the loss of protein, fluid and fat into the bowel.
Primary Intestinal Lymphangiectasia is a congenital disorder that is due to an idiopathic abnormality of lymphatic drainage. Lymphangiectasia is a prominent feature of Protein Losing Enteropathy or PLE.
Secondary Lymphangiectasia is usually associated with obstructive lesions of the lymphatic system. Lipogranulomatous lesions within and around the lymphatics are commonly observed, and may even be present in other organs. It is possible that secondary Lymphangiectasia develops in dogs with a congenitally compromised lymphatic system that leads to leakage of lymph. Lymphatic leakage then leads to a granulomatous response, leading to lymphatic obstruction and Lymphangiectasia. Lymphatic stasis can also arise due to venous hypertension, as is the case in right-sided heart failure. Lymphatic stasis results in lymphatic hypertension, which causes interstitial fluid to leak out into the abdominal cavity and into the lumen of the intestine. Lymphatic obstruction also causes a loss of lymphocytes into the intestinal lumen. Lymphangiectasia is therefore characterized by hypoproteinemia as well as lymphopenia. However, lymphopenia is not specific for Lymphangiectasia, especially since lymphopenia is common in animals with a stress response during disease states.
Protein-losing enteropathy is diagnosed by excluding other causes of hypoalbuminemia. During physical examination the patient is carefully evaluated for signs of heart failure and/or blood loss. A CBC, serum chemistry profile, and serum pre- and postprandial bile acid concentrations are useful to evaluate the patient for possible hepatic failure. Diarrhea for Intestinal Lymphangiectasia is usually mild or inapparent, in comparison with other protein-losing enteropathies.
This condition can not be cured but it can generally be well-managed by you and your veterinarian. Remissions of several months with occasional flare-ups are common.
The major goal of therapy is to reduce the loss of proteins into the intestine, to restore normal protein levels in your dog. This is done through diet, and medication to reduce inflammation in the intestinal wall. An ideal diet for dogs with intestinal lymphangiectasia contains minimal fat, and an ample quantity of high-quality protein. There are commercial prescription diets available which fulfill these requirements, or your veterinarian can give you information to prepare a low-fat diet at home. In either case, you will need to supplement your dog's diet with fat-soluble vitamins, due to the poor absorption of fat that occurs with this condition.
Corticosteroids are given to reduce inflammation, and thereby reduce loss of protein and associated diarrhea. Your veterinarian may also prescribe antibiotics.
In general the prognosis for canine patients with PLE of inflammatory origin is guarded. Many patients with severe inflammatory bowel disease will eventually respond, but the therapy is often protracted and may need to be life long. Lymphangiectasia also carries a guarded prognosis. Response to therapy is unpredictable and is affected by the severity of the disease process at presentation. Patients that are anorectic and severely malnourished at presentation have a poor prognosis.
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.
BIOPSY
As mentioned, there are four likely causes of protein-losing enteropathy. To distinguish them and initial the correct treatment, an intestinal biopsy is essential. This can be done surgically or via endoscopy but rational treatment is not possible without a tissue sample.
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 azathioprine are commonly used, especially if inflammatory bowel disease is 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 the addtion of Medium Chain Triglycerides (or “MCT’s”) 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.
INFLAMMATORY AND IRRITABLE BOWEL DISEASE
Typically, the animal doesn’t seem obviously sick. There has been weight loss over time but nothing drastic. There is simply a chronic problem with vomiting, diarrhea or both. Inflammatory bowel disease is probably the most common cause of chronic intestinal clinical signs and would be the likely condition to pursue first.
The treatment for inflammatory bowel disease is suppression of the inflammation. In milder cases of large intestinal inflammatory bowel disease, Metronidazole (Flagyl) might be adequate for control but usually Prednisone is needed. Prednisone will work on inflammatory bowel disease in any area of the intestinal tract. In more severe cases, stronger immune suppression may be needed. Some animals are able to eventually discontinue treatment or only require treatment during flare-ups. Others require some medication at all times. Long term use of Prednisone should be accompanied by appropriate periodic monitoring tests due to the immune suppressive nature of this treatment.
Dietary manipulation may also be helpful in the management of inflammatory or irritable bowel disease depending on the patient’s interest in newer foods.
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