Diarrhea in older dogs

Diarrhea in older dogs

About 90% of veterinary consultations are for gastrointestinal problems in our pets. This is because many systemic or digestive diseases cause diarrhea. For gastrointestinal pathology, this is the most common symptom. Most changes in feces occur when the animal’s diet has been affected in some way. However, when it comes to diarrhea in older dogs a comprehensive diagnosis should be initiated. Because elderly dogs‘ immune systems are fully developed, it is unlikely that the diarrhea is being caused by a dietary problem. For this reason, we must find out if our pet is suffering from any common disease of its age.

As diarrhea in older dogs is a common reason for a visit to the vet, in this article we will talk about the most likely causes that can lead to it. Nevertheless, we should always go to the vet if our pet is not feeling well . Only he would be able to tell us what is wrong with him and how to treat him.

Diarrhea in older dogs
Diarrhea in older dogs

Diarrhea in older dogs: differential diagnosis

In diagnostic methods, the first distinction to be made is. Because different diseases and deformities present a similar clinical picture, the veterinarian must rule out potential problems. When it comes to diarrhea in large dogs, this exclusion process is usually quite lengthy and includes blood, stool and urine tests. In addition, the vet may also require X-rays, ultrasound or a biopsy of part of the intestinal tract. It is also likely that the veterinary specialist will want to look at diet and the use of empirical medication when trying to diagnose an affected pet. However, the first step to get closer to the answer is to determine what type of diarrhea our dog is suffering from.

In some cases, dogs may present with different types of diarrhea. In addition, if it is chronic, acute or intermittent diarrhea should be taken into account in order to correctly perform the differential diagnosis. To be considered acute, it must last less than two weeks. If it lasts longer, diarrhea is considered chronic. When periods of recurrence and recovery alternate, it is intermittent diarrhea.

types of diarrhea

In addition to defining diarrhea by its duration, it can also be distinguished by its point of origin: from the small intestine or from the large intestine. In the first case, the animal usually excretes abundantly twice a day. However, there has been no change in his effort or need to defecate. Diarrhea in the small intestine may be accompanied by loss of appetite, vomiting and weight loss. In the event that there is blood in it, the color will be black or have a grayish appearance.

On the other hand, when it comes to diarrhea occurring in the large intestine, the dog feels a greater need to defecate. As a result, the number of deposits increases. Usually, these cases are not accompanied by vomiting, loss of appetite, or weight loss. When there is blood, the color turns a bright red. In addition, the stool may become covered in mucus.

Diarrhea in older dogs: main causes

There are many diseases that can cause diarrhea in older dogs. From tumors, passing through various organs and even a simple change in diet can alter our pet’s poop. To know the cause of the animal’s discomfort, we must go to a veterinarian so that they can diagnose and treat it as soon as possible. Especially when it comes to large dogs, the time it takes to start treatment is crucial for them. Below we will mention the main reasons that can cause diarrhea in elderly dogs.

inflammatory bowel disease

In the case of inflammatory bowel disease, the lining of the digestive tract is affected, causing thickening and inflammation. This pathology is very common in older dogs and causes various symptoms: chronic or intermittent diarrhea, weight loss, anorexia and vomiting. When it occurs in the last part of the digestive tract where lesions occur, the diarrhea is watery and may contain mucus or even fresh blood.


Some of the main causes of diarrhea in older dogs are tumors such as lymphomas and adenocarcinomas. These cause chronic diarrhea in the animal and often lead to loss of appetite and weight. In addition to darkening stools, they also have a rancid and shiny appearance due to digested blood.

rectal polyps

Rectal polyps are growths of the lining of the intestinal wall, usually internally. And, despite their appearance, they are not cancer. Older dogs are more likely to develop this deformity. Symptoms of rectal polyps are chronic diarrhea and stools with blood and/or mucus.

kidney problems

There are certain organ malformations that can cause diarrhea in older dogs, despite the fact that their functioning is not directly related to the digestive system. Among those organs are the kidneys. When dogs have kidney disease, and especially in cases of high blood urea concentration, they may suffer from vomiting and diarrhea.

liver diseases

The liver plays a fundamental role in the metabolism of proteins, carbohydrates, fats, minerals and vitamins. For that reason, when an animal suffers from certain liver disorders, the first symptoms that usually appear are non-specific gastrointestinal ones. These include vomiting, anorexia and diarrhea. While vomiting is caused by a gastroduodenal ulcer, diarrhea is caused by a coexisting inflammatory bowel disease. When there is a blockage in the bile ducts, the stool usually feels stringy. As for the mane, it may be caused by cysts or changes related to coagulation.

diseases of the pancreas

Malfunctioning of the pancreas is also one of the main causes of diarrhea in older dogs. Of all pancreatic diseases, the most prominent is exocrine pancreatic insufficiency. When an animal suffers from pancreatic disorders, chronic diarrhea with vomiting and weight loss occurs due to a lack of pancreatic acinar cells. The stool is usually thicker and softer. Also, they give off a strong odor and have a lighter colour.