Blood in Dog’s Stool (Hematochezia)

Blood in Dog’s Stool (Hematochezia)

blood in dog's stoolblood in dog's stool
blood in dog's stoolblood in dog's stool

Overview of Blood in Dog’s Stool

Hematochezia is the presence of bright red, fresh blood in the feces. Hematochezia can occur in dogs and usually occurs with bleeding in the lower intestines (colon, rectum). Hematochezia should not be confused with melena, which is the passage of dark, tarry, black feces. Melena represents the passage of old, digested blood that has occurred with bleeding higher up in the intestinal tract.

The presence of hematochezia may be a symptom of either a minor problem, or a potentially more serious problem in the animal. One occurrence of hematochezia may be a minor and transient event. Repeated or persistent hematochezia is more serious and should not be ignored. There are several possible causes. The most common cause in older pets is cancer and in younger pets are parasites. General causes include:

General Causes of Bloody Stool in Dogs

  • Infectious agents, such as bacteria, protozoa, viruses, and intestinal parasites
  • Dietary intolerance/allergy/indiscretion
  • Cancer (neoplasia) of the lower bowel
  • Polyps (benign masses) in the colon or rectum
  • Inflammatory bowel diseases, such as colitis
  • Trauma to the lower bowel or anal area
  • Clotting disorders (coagulopathy)
  • Intussusception (the telescoping of one part of the bowel into another)
  • Miscellaneous diseases of the anus, rectum and colon

What to Watch For

  • Bright red blood in the feces
  • Possible straining to defecate
  • Increased number of bowel movements produced
  • Possibly no other clinical signs
  • Possibly other systemic signs of illness, such as excessive drinking, urinating, vomiting and diarrhea, lethargy, poor appetite, weight loss

Diagnostic Tests for Hematochezia in Dogs

  • Rectal examination
  • Complete blood count (CBC)
  • Biochemical profile
  • Urinalysis
  • Fecal examination
  • Coagulation profile
  • Abdominal X-rays (radiographs)
  • Abdominal ultrasound
  • Colonoscopy

Treatment of Hematochezia in Dogs

There are several things your veterinarian might prescribe to treat your pet’ symptoms. These include:

  • Changes in the animal’s diet
  • Fluid therapy
  • Deworming medications for intestinal parasites
  • Antibiotics for bacterial infections
  • Motility modifying drugs that change the rate of movement of food through the intestines
  • Intestinal protectant/adsorbent drugs to coat, protect, and sooth the gastrointestinal tract

Home Care

At home administer any prescribed medications as directed by your veterinarian and follow any dietary recommendations closely.

You should also observe your pet’s general activity and appetite, and watch closely for the presence of blood in the stool, or a worsening of signs. If any changes occur, notify your veterinarian.


In-Depth Information on Bloody Dog Feces

Hematochezia refers to the presence of red or fresh blood in the stools, and must be differentiated from melena, which is the presence of black, tarry stools. The causes, diagnostic tests, and treatment protocols for hematochezia often differ from those for melena.

Hematochezia is often a sign of lower gastrointestinal disease. In some cases it is an indication of a minor, transient problem. In other cases it is indicative of a serious underlying disease that can become an emergency requiring intensive therapy. Hematochezia may be the only clinical sign seen, or it may be accompanied by other signs, especially straining to defecate. Obtaining a detailed history and through physical examination are essential when evaluating these patients.

Causes of Bloody Stools in Dogs

There are many potential causes of hematochezia. The most common causes are usually associated with the gastrointestinal tract, although in some cases, the cause is completely unrelated (e.g. clotting disorders or coagulopathies). It is important to determine the cause of hematochezia, as specific treatment is often necessary for these patients.

  • Numerous infectious agents may result in hematochezia. These include viral infections such as parvovirus and corona virus, bacterial infections such as Clostridium and Salmonella, protozoal agents such as coccidiosis, and intestinal parasites such as hookworms and whipworms.
  • Dietary intolerance and indiscretion from eating spoiled food, overeating, ingesting foreign material (especially bones), a sudden change in diet, or eating people food may cause inflammation of the lower bowel and hematochezia.
  • Dietary allergy to certain food substances, such as to particular proteins, lactose, high fat content, and certain food additives may also cause colitis with hematochezia.
  • Masses of the colon, rectum or anus may cause bleeding and produce hematochezia. Such masses include benign (polyps) and malignant (cancer) tumors.
  • Persistent hematochezia is a common sign of inflammation of the colon, sometimes referred to as colitis. Many of the causes of hematochezia listed above also cause colitis. Colitis can also occur for unknown, immune-related, or poorly defined reasons, and may require a colonic biopsy to identify the type of inflammation present.
  • Trauma of any sort can cause hematochezia. Examples include bite wounds to the anal area, fractures of the pelvis that disrupt the colon or rectum, the passage of sharp ingested objects (e.g. bones, needles, tacks, etc.), and the insertion of instruments or materials into the rectum (e.g. examination scopes, enema syringes, etc.).
  • Bleeding disorders (coagulopathies) of the body may result in bleeding from the lining of the lower bowel. There are numerous types of bleeding disorders that may occur in animals. Examples include thrombocytopenia (decreased numbers of platelets), ingestion of rat poison that contains anticoagulants, inherited clotting disorders (e.g. hemophilia, abnormal platelet function problems, etc.), disseminated intravascular coagulation (DIC) from massive infections or organ failure, and severe liver disorders.
  • Intussusception (the telescoping of one part of the bowel into another) secondary to foreign bodies, tumors, or parasites can cause hematochezia.
  • Hemorrhagic gastroenteritis (HGE) is a syndrome seen in dogs whose cause is unknown. It usually presents with acute bloody diarrhea, with or without vomiting. The bleeding associated with this disease can be very dramatic.
  • Stricture (narrowing) of the anus or colon, secondary to previous trauma, inflammation, cancer or a foreign body may result in bleeding, especially as stools are passed.
  • Anal sacculitis (inflammation of the anal sacs) or anal sac abscessation can change the consistency of the fluid in the anal sacs to a bloody liquid. This liquid may coat the stools as they are defecated.
  • Perianal fistulae are ulcerations or tracts that are visible in the skin around the anus. If these tracts communicate with the rectum, then hematochezia may occur.
  • Proctitis is inflammation of the rectum and is often associated with colitis.


Diagnosis In-depth on Bloody Stool in Dogs

Obtaining a complete medical history, and performing a thorough physical examination are necessary in order to create an appropriate diagnostic plan for the patient with hematochezia. The physical examination often includes a digital rectal examination. In addition, the following tests may be recommended:

  • A complete blood count (CBC) to evaluate for the presence of infection, inflammation, anemia, and altered numbers of platelets
  • A biochemical profile to assess the overall health and function of various abdominal organs, and to help rule out other disorders
  • A urinalysis to evaluate the kidneys, the hydration status of the patient, and the presence of blood in the urine
  • Multiple fecal examinations for parasites, bacteria, protozoa, and the presence of occult blood (blood that is not visible with the naked eye)
  • A coagulation profile to assess the ability of the blood to clot
  • Abdominal radiographs (X-rays) to evaluate the abdominal organs and assess for the presence of a foreign body or tumor

Your veterinarian may recommend additional tests, based on results of the above tests and the clinical signs exhibited by the animal. These ancillary tests are selected on a case-by-case basis:

  • An abdominal ultrasound evaluates the size, shape and texture of abdominal organs and helps to determine the presence of tumors. Organs, lymph nodes, and masses can be sampled with a needle or biopsy instrument with the guidance of ultrasound. This test may require referral of your pet to a specialist in veterinary internal medicine or veterinary radiology to perform the procedure.
  • Bacterial fecal cultures may be recommended in those cases where a bacterial cause is suspected.
  • Colonoscopy (lower GI endoscopy) may be of benefit in the patient with hematochezia. Colonoscopy involves the passage of a viewing scope into the lower bowel to visualize the lining of the colon and to allow biopsy of any abnormal tissue. Colonoscopy is performed under general anesthesia, and may require referral of your pet to a specialist in veterinary internal medicine to perform the procedure.


Therapy In-depth for Bloody Stool

Supportive Care

Treatment of the symptoms may be necessary while diagnostic testing is underway, especially if the animal is severely ill or blood loss is dramatic. The following supportive measures may be instituted as needed to reduce the severity of symptoms or stabilize the animal.

  • Intravenous fluid and electrolyte therapy may be indicated in severe cases of hematochezia, especially if there are concurrent systemic signs of illness like vomiting, dehydration or lack of appetite.
  • Treatment for shock may be undertaken in weak or collapsed animals.
  • Food and water may be withheld for 24 hours or more.
  • Antibiotics may be started via injection.

    Symptomatic Care

    With mild cases or nonspecific cases of hematochezia, symptomatic therapy may be tried. Such therapy is aimed at reducing inflammation within the lower bowel and decreasing exposure to materials that are difficult to digest or pass in the stools. Symptomatic treatments are not a replacement for specific therapy. With any serious or persistent hematochezia, it is important to perform diagnostic tests that allow a specific cause to be identified, and then specific therapy is instituted. Examples of symptomatic measures include the following:

  • Changes in diet may be recommended, and may include a trial of either a high fiber diet or a hypoallergenic diet.
  • Thoroughly deworming the pet is often recommended, regardless of whether the fecal examination confirms parasitism. In some cases intestinal parasites are present, but they are difficult to detect on routine fecal screenings. A broad spectrum dewormer such as fenbendazole may be recommended.
  • Antibiotic therapy with oral Flagyl® (metronidazole), tylosin, or tetracycline may be recommended because these drugs alter the bacterial counts in the lower bowel and may have some mild anti-inflammatory properties.
  • Gastrointestinal protectants may be tried, such as the bismuth containing over-the-counter products.
  • Motility modifying drugs that change the rate of movement of food through the intestines may be helpful in some cases.

    Specific Treatments

    Once a diagnosis is made, then specific therapy may be instituted. Specific treatments are sometimes combined with supportive and symptomatic treatments to ensure the hematochezia resolves. Depending upon the cause, the following may be considered:

  • Common treatments used for colitis include dietary changes and oral antibiotic or antibacterial (e.g. sulfasalazine) medications.
  • Corticosteroids may be indicated in some forms of immune-related colitis.
  • Treatments for clotting disorders may include Vitamin K therapy, transfusions of either blood or plasma, and corticosteroids for certain platelet problems.
  • Masses of the colon or rectum are surgically removed whenever possible.
  • Intussusceptions often require correction via require abdominal surgery.
  • Hemorrhagic gastroenteritis usually responds to intensive intravenous fluid therapy and antibiotics.
  • The presence of colonic foreign bodies, such as bones, metallic materials, etc., may sometimes necessitate cleansing enemas or manual removal with the animal under general anesthesia.
  • A variety of treatments exist for perianal fistulas, strictures, and anal sac disease.
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