The presence of diarrhea in dogs should always be cause for concern. There are a plethora of causes of both acute and chronic diarrhea in dogs, including infectious causes, toxins, inflammation or disease of the intestinal tract and parasites. Diarrhea can have a devastating effect on the body due to its dehydrating effect, and left untreated it can lead to blood sugar depletion, circulatory collapse and death. Although mild cases of diarrhea may resolve without intervention, diarrhea accompanied by vomiting, lethargy or any other behavioral changes should be treated as a medical emergency. Because the severity of the cause of diarrhea is not immediately present at onset, prompt medical attention must be sought to quickly diagnose and treat the underlying problem.

Diarrhea is always a symptom of an underlying problem, and not a disease in itself. Diarrhea can be used to describe a varying severity of a problem, from occasional loose stools to a continuous watery stream of feces. Unfortunately there are many potential causes of diarrhea in dogs, and determining the cause can require a joint effort by you and your veterinarian.

One of the most common causes of diarrhea is intestinal upset. A sudden change in the type of food, giving an unfamiliar treat, or feeding table scraps can cause a bout of diarrhea. Diarrhea caused by food changes can often be resolved at home, so long as the diarrhea is not severe, and the dog continues to act and feel normally. Withholding food for 24 hours will allow the dogs digestive system to settle down (while continuing to encourage water consumption). After 24 hours, small amounts of a bland diet, such as white rice and chicken, can be offered. If the diarrhea subsides, you can gradually place the dog back on their original diet, and transition slowly to the new diet. If the diarrhea does not improve, or gets worse, veterinary treatment may be required.

In order to avoid intestinal upsets due to dietary changes, all changes in food should take place over several days, to allow the dog to get used to the new food. For the first three days of a food switch, feed ¼ of the new diet and ‘¾ of the old food. If your dog is doing well, then feed a half portion new food and half old food for another three days, then ‘¼ old food and ‘¾ new food for another three days. This slow transition will help to minimize intestinal upsets and decrease the chances of an episode of diarrhea.

Although many dogs regularly receive table scraps, care must be taken to ensure that the types of human foods are not too rich for the dogs system. Fatty foods especially can cause diarrhea and vomiting, and can also cause pancreatitis, a form of inflammation in the pancreas that can lead to chronic digestive problems. In addition, while dogs love most of the types of meat that we may be eating, the form they are accustomed to (in their dog food) is highly processed. Giving large amounts of meat from human plates can be far too rich for the dog, and cause diarrhea. It is also important to remember that dogs should NEVER be given turkey or chicken bones, as these can splinter into small pieces and puncture the stomach and intestines.

Intestinal Parasites can Cause Diarrhea in Dogs

Intestinal parasites are a very common cause of diarrhea in dogs. There are many types of parasites that can infect dogs, and diarrhea is often one of the most common symptoms of a parasite infection.

Roundworms are one of the most commonly seen intestinal parasites in puppies. Although roundworms are not commonly active in most adult dogs, puppies are especially susceptible to their presence and side effects. Dogs ingest the roundworm egg in the soil, and puppies can be passed the worm from their mothers. As the eggs hatch in the intestine, the larva is then carried to the lungs via the bloodstream. From the lungs, the worms crawl up the windpipe and cause gagging and coughing, before returning to the intestine to grow into adults. Roundworms can grow to up to seven inches long and appear spaghetti-like, long and thin. A pot-bellied appearance, poor growth and a rough, dull hair coat are signs of a worm infestation. Diarrhea and vomiting may be present as well, and the dog may expel worms in their stool or vomitus. If allowed to continue unchecked, the worms can cause pneumonia, intestinal obstructions and death.

Hookworms can be seen in dogs of all ages, but are most common in warmer, humid climates. Transmitted by ingestion of contaminated feces, mature hookworms attach to the lining of the intestinal tract and feed on the blood supply there. In pregnant dogs, the hookworms migrate into the fetuses, and begin to infest the puppies before they are even born. Hookworms in puppies can be devastating, as they can cause severe anemia, weakness and bloody diarrhea.

While not a worm, Giardia is an intestinal parasite caused by a single-celled organism that lives in the intestines of infected animals. Recent research has shown that Giardia is present in up to 11% of the general population of pets, and as many as 50% of puppies. Giardia can be transmitted from pet to pet, through contaminated feed or water, and through the soil. Pets who attend dog-park, doggy day care or are kenneled are at higher risk for infection. The most common symptom of Giardia is diarrhea of varying severity. However, many animals who are infected with Giardia can show no symptoms for extended periods of time, which makes routine testing even more important.

Coccidia is another single-celled organism that infects the small intestine of dogs. Dogs with coccidia may show know signs of illness, and some may have severe bouts of watery stools and bloody diarrhea, vomiting, depression and fever, and even death as a result of severe dehydration. These severe side effects of coccidia are most common in puppies and adult dogs suffering from other illnesses.

Diarrhea in puppies and young is of particular concern, because if is often the first symptom of severe and potentially fatal viral diseases such as the parvovirus, coronavirus and distemper.

Parvovirus is most commonly found in young dogs than adults, and puppies that are unvaccinated, or have not yet completed their vaccination series are most susceptible. The parvovirus attacks and kills the cells in the intestinal lining, rendering the dog unable to absorb nutrients or liquids. Dogs with parvo develop a high fever, lethargy and loss of appetite. Profuse, liquid diarrhea occurs as the damage to the intestinal tract progresses, and may be foul smelling, or have blood in the stool. The diarrhea leads to severe dehydration, shock and death, and is often fatal, even in dogs diagnosed and aggressively treated for the disease. Vaccination is the best prevention for development of Parvo.

Like Parvo, the coronavirus is a highly contagious virus causes gastrointestinal problems. Although adult dogs that contract corona may simply show symptoms like stomach flu, and recover within a few days without treatment, puppies can develop far more serious infections and complications. The signs of corona are similar to those of parvo- profuse watery diarrhea, which if left untreated can cause severe dehydration and secondary complications.

Canine Distemper Virus is a devastating disease that is highly contagious, and infects unvaccinated dogs and puppies. This virus normally localizes in the brain, intestinal tract and upper respiratory tract. A high fever is usually the first sign of infection, along with a cough, sneezing, and green discharge from the nostrils. The virus then affects the intestinal tract, causing vomiting, and dark, tar colored diarrhea. Finally the virus travels to the brain and spinal cord, causing seizures and uncontrollable twitching.

There is no cure for distemper- medical treatment is aimed at controlling the symptoms and supporting the dogs body to help survive the infection. Even with aggressive treatment, Distemper is often fatal, and dogs that do survive are often left with lifelong seizure disorders and other nervous system problems. Vaccination is the best way to prevent distemper.

Other causes of acute diarrhea in dogs can include bacterial infections, such as salmonella and E.coli, toxin exposure, such as from insecticide and lead, and even stress.

Treatment of acute diarrhea in dogs is aimed at diagnosing the underlying problem, and correcting that. If your dog has had loose stools for less than 24 hours, but is otherwise acting normally (normal energy level, eating and drinking normally), you may be able to take a conservative approach, and wait and see how he does. However, if your dog is showing any additional signs of distress, or has had increasing amounts of diarrhea for any length of time, a visit to your veterinarian in required.

Your veterinarian will first take a full history on your dogs condition, when the diarrhea first started, were there any precipitating factors, etc. After a comprehensive physical exam, your veterinarian may recommend:

Fecal testing– a sample of the diarrhea will be obtained, and checked for evidence of parasites such as roundworms and coccidia. In addition, an antigen test may be run on the fecal sample to check for the presence of Giardia.

Fecal Cultures may be recommended to test for the presence of bacteria in the stool, such as salmonella.

Blood work– Blood chemistries look at a variety of body systems, and will give your vet a reading as to the basic health of your dogs major organs such as the kidneys and liver. The CBC evaluates the components of your dogs blood, including red blood cells, white blood cells, and platelets. The CBC will help to diagnose or rule out infection as a potential cause of your dogs diarrhea.

Parvo test– In puppies, a parvovirus antigen test may be run. This quick ‘snap’ type test is run on a small sample of feces, and results may be available within minutes. The sooner parvo can be diagnosed and treated, the greater chance your puppy has for a favorable outcome.

X-rays– Radiographs of your dogs abdomen may be recommended to rule out potential intestinal obstructions, or foreign bodies that your dog may have ingested.

Treatment of your dogs diarrhea depends on what your vet suspects may be the cause. In cases of intestinal upset, a bland diet may be all that’s needed to settle the stomach. Parasites can be treated with de-wormers, and a drug may be prescribed to help return the digestive system to working order. Treatment of severe diarrhea will begin with intravenous fluid therapy, and balancing of electrolyte levels to combat the fluid loss caused by the diarrhea.

While acute cases of diarrhea can be cause for great concern, chronic diarrhea, while less common, is also reason for a visit to your veterinarian.

Diarrhea that persists for three or more weeks is considered chronic. Often the stool may begin to firm, only to become soft and unformed again. It is not uncommon to see mucous or even small amounts of blood in the sample. Because chronic diarrhea can lead to poor digestion and absorption of nutrients, often dogs will not eat well, have a low energy level and poor quality hair coat.

Food allergies and intolerances are a common cause of mild chronic diarrhea. Similar to lactose intolerance in people, dogs may have or develop allergies or sensitivities to variety of ingredients in dog food, leading to chronic inflammation in the intestinal tract.

Pancreatitis can present in dogs in both an acute form, as well as a chronic problem. The pancreatic gland is responsible for secreting hormones such as insulin and glucagons into the bloodstream to regulate blood sugar levels, as well as making the digestive enzymes that break down food for digestion. Pancreatitis, or inflammation of the pancreas, can cause these digestive enzymes to decrease, and in severe cases the enzymes may begin to digest the actual organs of the dog instead of digesta. Diarreha, abdominal pain, vomiting and a poor appetite are the symptoms of pancreatitis, but because these symptoms are shared with so many other gastrointestinal problems, it can be hard to diagnose.

Inflammatory bowel disease (IBD) can also be a cause of chronic diarrhea in dogs. In affected dogs, the intestine is taken over by inflammatory cells, eventually leading to scar tissue throughout the lining of the digestive system. Although the exact cause of IBD is unknown, nutrition, genetics and the immune system are thought to play a role in its development. Dogs with a long history of diarrhea or weight loss that have been found to be free of parasites and diarrhea causing agents should be considered for IBD. Diagnosis of IBD can be difficult, and often requires an intestinal biopsy to confirm. Treatment is aimed at reducing the inflammation, as well as dietary changes to provide a more easily digestible food source.

Whether chronic or acute, diarrhea is almost always a sign of an underlying medical condition that needs to be addressed. Because diarrhea in itself has the potential to be life threatening, any dog suffering from more than a short-term bout of diarrhea, or dogs showing signs of other medical problems, should immediately be seen by a veterinarian. In addition, because young are so susceptible to several potentially fatal viruses, the presence of diarrhea in any puppy should be treated as a medical emergency until proven otherwise.


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