What is protein-losing enteropathy?
The word “enteropathy” means any disease of the intestinal system. Protein-losing enteropathy (PLE) is not a specific disease, but a group of diseases that cause the loss of proteins from the bloodstream into the gastrointestinal (GI) tract. Primary GI disease, heart disease, and diseases of the lymphatic system can all cause PLE.
When the body is functioning normally, small amounts of blood proteins that end up in the GI tract are broken down and re-absorbed by the body. When disease occurs, protein loss may exceed protein manufacturing by the body. This is called “hypoproteinemia”.
When hypoproteinemia is severe, fluid may leak from the circulatory system into the abdomen or chest, or out of the tiny blood vessels in the limbs, causing swelling of the legs.
What breeds most commonly get PLE?
Certain breeds are over-represented among PLE patients: the soft-coated wheaten terrier, Yorkshire terrier, Maltese, Chinese shar pei, rottweiler, basenji, Irish setter, and Norwegian lundehund. There may be a genetic predisposition in some of these breeds.
What are the signs of PLE?
Diarrhea is one common sign of PLE. The diarrhea may come and go, may be continuous, or may be the consistency of water. But some dogs with PLE can have normal stools.
Dogs with PLE generally have a difficult time holding their weight and may become lethargic. Vomiting may occur but is inconsistent. Appetite may initially increase, as affected dogs cannot absorb nutrients properly, but will eventually decline as they become sicker.
Other signs of PLE include fluid in the abdomen (ascites), fluid under the skin (edema) on the under-side of the body or in the limbs, difficulty breathing from the pressure of fluid build-up inside the chest cavity (pleural effusion), and thickened loops of intestine.
What diseases cause PLE?
The lymphatic vessels carry a clear fluid that contains white blood cells, called “lymph”, throughout the body. Lymphatic diseases that can lead to PLE include:
- Lymphangiectasia — dilation of the lymphatic vessels in the GI tract
- GI lymphoma/lymphosarcoma — cancer of the lymphoid tissues around the body, including the lymphoid tissues within the GI tract
- Infiltration of the GI tract by granulomatous tissue which interrupts lymphatic flow
- Congestive heart failure, causing increased pressure within the lymphatic system
Diseases that directly affect the GI tract and can lead to PLE include:
- Bacterial gastroenteritis (e.g., salmonella)
- Fungal gastroenteritis (e.g., histoplasmosis)
- Parasitic enteritis (e.g., whipworms)
- Inflammatory bowel disease (IBD)
- Adverse food reactions (e.g., food intolerance)
- Mechanical GI disease (e.g., chronic foreign body irritation, without creating a blockage)
- Intestinal cancer (e.g., carcinoma)
- Ulcers in the stomach or intestines
- Viral gastroenteritis (e.g., parvovirus)
How is PLE diagnosed?
Your veterinarian will perform diagnostic testing if they see clinical signs that suggest PLE. Bloodwork often shows low blood protein, including both low albumin and globulins.
Albumin is a small protein that is very important in the bloodstream. It helps transport other molecules and helps keep fluid inside the blood vessels. Globulins make up the remainder of the proteins in the blood and are important for different functions including blood clotting, and immune responses.
Changes in the complete blood count (CBC) may include low red blood cell counts (anemia), and increased or decreased white blood cell counts. Imaging with an ultrasound may show fluid buildup in the chest or abdomen, and thickened bowel loops.
Other testing may include fecal examination to look for infectious organisms, measurement of vitamin B12 (cobalamin) in the blood to indicate whether there is decreased ability to absorb nutrients, and measurement of folate in the blood to indicate whether there is an imbalance in the normal bacterial populations in the GI tract. Definitive diagnosis may depend on biopsies of the stomach and/or intestines.
How is PLE treated?
Severe hypoproteinemia may require hospitalization for plasma transfusions or intravenous fluids to keep fluid within the blood vessels. If a dog has difficulty breathing, the veterinarian may need to remove fluid from the chest or abdomen.
In general, treatment of PLE is determined by the underlying disease. Ongoing monitoring, including exams and other tests, will help guide best treatment and may reveal the underlying cause over time, if not already diagnosed. Modified nutrition is part of ongoing management because the primary, underlying disease may not be treatable. The long-term prognosis in most dogs depends largely on the underlying cause of the PLE.
