Protein Losing Enteropathy: Intestinal Protein Loss in Dogs

Protein losing enteropathy in dogs is a condition that affects the ability of the intestines to absorb protein from the diet. Dogs with protein losing enteropathy have to deal with a net loss of protein, which means they lose more protein than they are able to take in from the diet. This can affect the dog’s health quite severely, as proteins are needed for numerous roles within the body.

Dogs with protein losing enteropathy (PLE) are still able to absorb protein from the diet through the intestines, but these proteins are able to leak back in to the gut and end up being excreted.

The development of PLE can be a result of one of many factors. Two conditions that are often involved in the development of PLE include canine inflammatory bowel disease (IBD) and lymphangiectasia (a condition where lymph vessels become dilated). There are many more acute or chronic conditions that can increase intestinal permeability to proteins, these are listed below.

Urinary loss of proteins and liver disease need to be ruled out before the diagnosis of PLE.

Why Intestinal Protein Loss is a Problem

One of the main proteins that is lost through protein losing enteropathy is albumin. Albumin is the most abundant blood plasma protein, and is responsible for transporting various important biological and chemical compounds around the body.

A net loss of albumin is bad news for the body, as vital biological systems depend on it. As such, a decrease in albumin will cause the breakdown of other proteins such as muscle. This muscle wasting, coupled with diarrhoea and vomiting will result in noticeable weight loss.

Breeds Predisposed to Protein Losing Enteropathy

Certain breeds are more likely to develop protein losing enteropathy than others. A genetic predisposition to a disease can usually be traced back to a single individual early in the history of the breed that had the genetic defect, particularly in pedigree breeds where the gene pool is often limited.

Breeds more likely to develop protein losing enteropathy include: ¹

• Soft coated whetan terrier
• Basenji
• Yorkshire Terrier
• Norwegian Lundehund
• Poodle
• Maltese Terrier
• Shar Peis

Symptoms of Protein Losing Enteropathy

The symptoms of protein losing enteropathy can be quite easily confused with various other diseases, such as irritable bowel disease or chronic gastritis. Often, the first symptom that indicates a problem, is weight loss. The weight loss associated with protein losing enteropathy can be quite rapid. Diagnostic tests performed by your vet will rule out other possible diagnoses.

The main symptoms to look out for include:

• Diarrhoea – Your pet may develop chronic diarrhoea as a result of protein losing enteropathy, which may contribute to weight loss. However, this symptom may not be present in all dogs with protein losing enteropathy.
• Weight loss – Protein is required to develop muscle and is an essential part of many cells within the body. A net loss of protein will cause the body to breakdown existing muscle to ensure it is still able to produce the more essential biological components.
• Lethargy – A lack of energy as a result of net protein loss.
• Difficulty breathing – This is due to a build up of fluid between the lungs and the chest wall.
• Swollen abdomen – Again, due to a build up of fluid beneath the skin.

If you notice that your pet has started to dramatically lose weight, you should consult your veterinarian.

Image credit Nottingham Vet School

Causes of Protein Losing Enteropathy

The causes of protein losing enteropathy can essentially be split in to two categories:

1. Complications of the lymphatic system – part of the circulatory system that is responsible for transporting lymph. Lymph mainly carries white blood cells, proteins and fats, making it an important part of the immune system.
2. Diseases that affect intestinal tissue, or the intestinal lining – Damage or inflammation to the intestines can impact on its ability to function correctly.

• Tumours – Cancerous or benign tumours are both a result of abnormal cell growth. The development of a tumour within the lymphatic system or the gastrointestinal system can reduce the ability of the body to absorb protein.
• Viral, bacterial, fungal or parasitic infections – Infections such as parvovirus, can cause damage and inflammation to the gut, impeding its ability to absorb protein and other nutrients from digested food.
• Food allergies – Food allergies can irritate the gastrointestinal system, causing inflammation. Food allergies may also be responsible for numerous other pet health issues such as itchy skin.
• Stomach or intestinal ulcers – Ulcers can damage gastrointestinal lining.
• Lymphangiectasia (Dilation of the lymph vessels) – Dilation of the lymph vessels allows protein-rich lymph to ‘leak’ back in to the intestines, causing the digested protein to be excreted instead of being utilised by the body.
• Intestinal inflammation (e.g. Inflammatory bowel disease) – There can be a number of causes of intestinal inflammation. Inflamed tissue is unable to function as efficiently as normal tissue, so for example, if the intestinal lining becomes inflamed it will be unable to absorb as much protein, and other nutrients, as usual.

Treating Protein Losing Enteropathy

At present there is no medication available to directly treat protein losing enteropathy. In many cases, the underlying issues can be treated, which can reduce the severity of the disorder and make it more manageable through lifestyle changes. As the underlying issues can vary, the appropriate treatment will need to be determined by your veterinarian.

Patients that have developed swelling as a result of fluid build up may be prescribed diuretics. Diuretics aid the removal of excess fluid from the body and as such, can reduce swelling.

Dogs with severe protein losing enteropathy may require a plasma transfusion. This can increase the amount of the biologically important protein albumin. Some dogs may also need treatment with anticoagulants that will reduce the likelihood of blood clots developing due to a lack of the protein antithrombin.

Management of Disease

As mentioned earlier, there is ‘no cure’ for protein losing enteropathy, it needs to be managed through lifestyle changes.

One of the best ways to manage protein losing enteropathy is by altering your dog’s diet. One of the most important aspects of a protein losing enteropathy diet is to restrict the amount of fat. Dietary fat increases the protein content of lymph and also increases the flow of lymph. This results in more protein being lost through the lymphatic system. As a recommendation, <20% of your dog’s calorific intake should come from dietary fat, if they suffer from protein losing enteropathy.

Meals should also be highly digestible but low in fibre, as fibre will decrease the energy density of your pet’s diet, which will already be lowered by the reduction of fat. Feeding a hypoallergenic pet food, such as those given to pets with food allergies, can be beneficial as they contain hydrolysed proteins that are more easily absorbed.

Providing your dog with vitamin supplements such as pumpkin supplement for dogs may also be beneficial.  It is not uncommon for dogs with protein losing enteropathy to develop vitamin and mineral deficiencies. For example, calcium deficiency can be a problem as a large proportion of calcium is bound to albumin in the body – a protein that is lost through protein losing enteropathy. In this instance, a calcium supplement may be beneficial. You may also want to consider general multivitamins, formulated for dogs.