My Dog has Blood in its Stool

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“My dog has blood in its stool” is a common complaint to veterinarians. Any blood in the stool of your dog is abnormal, and should be cause for medical concern. There are many causes of bloody stool, and it is important to consult your veterinarian if this condition is seen in your dog.

“My dog has blood in its stool - why?”

Blood in the stool often accompanies diarrhea, and may vary in severity. Often times dogs that have had a bout of diarrhea will begin to have flecks of blood in the feces after several bowel movements. In other cases, large amount of frank blood may be present. Because any irritation to the lining of the intestines can cause them to bleed, blood in the feces indicates a serious underlying condition of the dogs intestinal tract.

The most common causes of blood in the stool include:

  • Parasites 
  • Viral infection
  • Hemorrhagic Gastroenteritis

Parasites are the least serious cause of blood in the stool. However, once a parasite infection has progressed to the advanced stage of causing blood in the feces, it is likely a serious infestation that may be difficult and even dangerous to treat.

Hookworms are intestinal parasites that can infect dogs of all ages, seen mostly in warmer, humid climates. Transmitted through the ingestion of contaminated feces, hookworms bite and attach themselves to the lining of the intestines, feeding on the blood supply there. Hookworms can be transmitted to puppies in utero and begin to do their damage before the puppies are even born. The parasite can be devastating to puppies, causing blood loss and severe anemia, weakness, and bloody diarrhea. There are many dewormers available that can treat hookworms, but in severely affected puppies supportive care may be necessary to stabilize and support their bodies from the infestation.

Other parasites that can cause GI bleeding and blood in the stool include whipworms, coccidiosis and Giardia.

Two of the most serious and potentially deadly diseases, Canine Parvovirus and Canine Distemper virus both have bloody diarrhea as a major symptoms of infection. Both of these diseases are highly contagious, and often deadly, even with treatment.

Canine parvovirus is a devastating disease, especially in puppies that are unvaccinated or have not yet finished their vaccination series. This viral form of gastroenteritis attacks the cells of the intestines, where nutrients and liquids are normally absorbed. Profuse, malodorous watery diarrhea and blood in the stool develops as the intestinal lining sloughs. Affected dogs develop a high fever, lethargy and loss of appetite in addition to diarrhea and vomiting. These lead to severe dehydration, electrolyte imbalance, shock and can quickly become fatal, even in dogs diagnosed and aggressively treated for the disease.

Like parvo, canine distemper is a highly contagious, devastating disease that affects unvaccinated dogs and puppies. The virus attacks the respiratory tract, intestinal tract and even the brain. Dogs affected with distemper first run a high fever, along with a cough, sneezing, and green mucous discharge from the eyes and nose. As it progresses, the virus attacks the intestinal tract, causing vomiting and dark, tar colored diarrhea (so colored due to blood in the stool). Finally the virus travels to the brain and spinal cord, causing uncontrollable twitching and seizures. Even with aggressive medical treatment to treat the symptoms, 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.

Hemorrhagic Gastroenteritis (HGE) is the sudden onset of bloody diarrhea in formerly healthy dogs. While young, toy and miniature breed dogs are most commonly affected, any dog can develop HGE.

The underlying cause of HGE is unknown, but is thought to be an abnormal response to bacteria, bacterial endotoxins (i.e. salmonella or clostridium), intestinal parasites, or even food allergies. In addition, stress and hyperactivity may contribute to the development of the condition. Often the condition can occur without any obvious change in diet, environment or daily routine.

Acute, bloody diarrhea, vomiting, depression and anorexia are the most common signs of Hemorrhagic Gastroenteritis. Dogs may not appear to be dehydrated, but blood tests will often show signs of severe dehydration due to blood loss through the feces. HGE is highly treatable, but left untreated it has a high fatality rate.

“My dog has blood in it’s stool- what do I do?”

If your dog has blood in its stool, a veterinarian should be consulted immediately. After a complete physical exam, a fecal sample may be examined for the presence of parasites or bacteria. Parasites can be easily treated with deworming medication and most cases will clear up quickly after treatment.

An antigen test can be performed to test for Parvo in young dogs. If positive, aggressive treatment in the form of blood tests, IV fluids and other supportive care must begin immediately for the best possible outcome. Depending on the severity of the illness, hospitalization for several days in addition to blood and plasma transfusions may be necessary to support the dog through the illness. Younger puppies are generally affected more severely, and have a higher mortality rate.

While there is no clear test to determine Distemper infection, diagnosis is made through the presence of symptoms. As with parvo infection, treatment of distemper is aimed at supportive care as the dogs body deals with the symptoms. Reducing and preventing high fevers is imperative, as the damage done to the brain can be fatal and life-long. Treatment can take days, and the full extent of damage done to the dogs body may not be apparent for several weeks after the virus is no longer active. Often fatal, prevention through vaccination is highly effective, and necessary for all dogs.

In dogs with HGE, supportive care initiated quickly can ensure a favorable outcome. Fluid therapy and antibiotics are the mainstays of treatment, as well as careful attention to restoring and maintaining appropriate electrolyte levels in the blood. Food and water are withheld for several days, and when the vomiting and diarrhea ceases, an easily digestible diet is added back slowly. Most dogs recover within 2-3 days, and generally have no lasting effects of illness.

Blood in the stool can have an array of causes. However, since blood in the gastrointestinal tract can signify a serious illness, any time blood appears in the stool it should be considered a medical emergency, and the dog should see a veterinarian immediately.

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