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Dr. Michael Salkin
Dr. Michael Salkin, Veterinarian
Category: Dog Veterinary
Satisfied Customers: 27467
Experience:  University of California at Davis graduate veterinarian with 44 years of experience
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My dog has not eaten in two days, throws up what she eats

Customer Question

My dog has not eaten in two days, throws up what she eats and every time she strains to go to the bathroom, a couple of drops of blood come out. She is not lethargic.
Submitted: 1 year ago.
Category: Dog Veterinary
Expert:  Dr. Michael Salkin replied 1 year ago.

Please clarify for me if you're seeing those drops of blood when she attempts to urinate or, instead, when she attempts to defecate.

Customer: replied 1 year ago.
Expert:  Dr. Michael Salkin replied 1 year ago.

Thank you. This is called hematochezia and can result from more disorders than I could list in this venue. In most cases, a colitis is found in a young dog such as Lilah. I'll post a synopsis of colitis for you below but whatever the cause, her two days of anorexia, vomiting, and hematochezia should prompt her being attended to by her vet at your earliest convenience. Please peruse the synopsis and then return to our conversation with further questions or concerns if you wish...


 Basic Information


The presence of red blood on the surface of or admixed into the stool


Species, Age, Sex

Dependent on underlying cause

  • Neoplasia more likely in older animals
  • Histiocytic ulcerative colitis: dogs < 2 years old
  • Perineal hernia: adult/older, male intact dogs

Risk Factors

The most common risk factor for hematochezia is colitis of any cause. Neoplasia is less commonly responsible. Coagulopathies are a rare cause of hematochezia.

Associated Disorders

Clinically significant anemia very uncommonly occurs as a result of hematochezia.

Clinical Presentation

History, Chief Complaint

  • Concurrent mucus in the stool, tenesmus (both are common), painful defecation, “scooting” behavior, licking/chewing/scratching the perineum are common manifestations of colonic or anorectal disease.
  • Animals with isolated hematochezia rarely present signs of systemic illness.
  • Weight loss and inappetence can occur with concurrent small-intestinal or pancreatic disease, histiocytic ulcerative colitis, or neoplasia.

Physical Exam Findings

  • Generally clinically healthy
  • The perianal area may be soiled with blood, fecal material, and/or mucus.
  • The anus may be inflamed, ulcerated, or painful.
  • A mass (neoplasm), swelling (anal sac abscess, perineal hernia, or neoplasm), or fissure (perianal fistula) around the anus may be visible.
  • A digital rectal examination is essential in any patient with hematochezia (intraluminal or extraluminal mass, stricture, anal sac mass or abscess, pain, melena).

Etiology and Pathophysiology

  • The blood is fresh (undigested), localizing the problem to the descending colon, rectum, or anus.
  • Conversely, melena represents oxidized blood as seen with digested blood. Rarely, colonic disorders may produce melena, instead of hematochezia, if colonic transit times are substantially increased (e.g., constipation).


Diagnostic Overview

  • Evaluation begins with history, physical exam, and digital rectal exam.
  • In otherwise well animals with normal physical exam findings, diagnostic testing can begin with fecal analysis and/or response to nonspecific, supportive treatment.
  • Further diagnostic evaluation is required in animals with signs of systemic illness, physical exam abnormalities, bleeding diathesis, and/or chronic/recurrent hematochezia.

Differential Diagnosis


  • Anus (e.g., anal sac disorders, perianal fistula, neoplasia, trauma)
  • Rectum and colon (e.g., colitis [most common], parasites, neoplasia, stress-associated)

Initial Database

  • Visual and digital anorectal examination, including anal sac palpation
  • Fecal flotation and direct examination for parasites
  • Fecal smear, culture for fecal pathogens, Clostridium enterotoxin detection
  • Results of trial therapy

Advanced or Confirmatory Testing

Further diagnostic evaluation is required in animals with signs of systemic illness, physical exam abnormalities, bleeding diathesis, and/or chronic/recurrent hematochezia.

  • CBC
  • Serum biochemistry profile
  • Urinalysis
  • Coagulation profile
  • Abdominal radiographs, ultrasound
  • Colonoscopy


Treatment Overview

Initial therapy consists of dietary change, broad-spectrum dewormer, and an antibiotic to control bacterial overgrowth. Unresponsive chronic cases may benefit from referral to a specialist for colonoscopy.

Acute General Treatment

Nonspecific trial therapy can be attempted in an animal without systemic signs:

  • Dietary modification as dictated by underlying disorder
  • Broad-spectrum anthelmintic (e.g., fenbendazole 50 mg/kg PO q 24h × 3 days)
  • Trial course of metronidazole (e.g., 7.5-10 mg/kg PO q 12h × 10 days), or tylosin (10 mg/kg PO q 8h for 21 days as treatment trial if suspecting inflammatory bowel disease, or 20 mg/kg PO q 12h for clostridial colitis), sulfasalazine (dogs: 20-40 mg/kg PO q 8h for 14-21 days, then taper by 25%-30% q 14-21 days; cats [use with caution given salicylate sensitivity]: 10-20 mg/kg PO q 24h maximum of 10 days, then taper to lowest effective dose/discontinue)

Chronic Treatment

Specific treatment depends on the underlying disease.

 Prognosis & Outcome

Dependent on underlying disease

Expert:  Dr. Michael Salkin replied 1 year ago.
Hi Norah,
I'm just following up on our conversation about Lilah. How is everything going?
Dr. Michael Salkin

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