Salmonellosis in Dogs

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Salmonellosis is a bacterial disease that most commonly causes enteritis (inflammation of the intestines), septicemia (systemic disease due to the presence of bacteria or their toxin in the bloodstream) and abortions. It is not uncommon for the infected individual to be a subclinical carrier, which is a carrier with no symptoms.

Salmonellosis is caused by any one of more than 2000 serotypes (subtypes) of the Salmonellae bacteria. It is seen in both dogs and cats. In dogs, clinical disease is most commonly seen in immature puppies and pregnant bitches.

What to Watch For

  • Lethargy
  • Depression
  • Weakness
  • Anorexia
  • Weight loss
  • Fever
  • Diarrhea (with or without blood)
  • Abdominal pain

    Diagnosis

  • Complete blood count (CBC)
  • Biochemical profile
  • Urinalysis
  • Fecal flotation
  • Platelet count
  • Screening thoracic (chest) and abdominal radiographs (X-rays)
  • Fecal Culture
  • Blood Culture

    Treatment

  • Depending on the severity of clinical signs, treatment options may include out patient care or may necessitate hospitalization. Affected individuals are contagious, and should be kept in isolation and handled carefully.

  • Food restriction may be recommended for those patients with severe gastrointestinal signs. Supportive care, to include fluid and electrolyte therapy, and/or intestinal adsorbents and protectants, may be indicated.

  • Antibiotic therapy may be indicated in certain cases, but contraindicated in others.

    Home Care and Prevention

    Administer all medication and return for follow-up fecal cultures as directed by your veterinarian. Prognosis varies depending on the individual and associated conditions. Be aware that salmonellosis is contagious to others animals and people.

    Keep animals vaccinated and feed a good quality food. Keep the environment clean and disinfected. Properly store feed and utensils. Reduce overcrowding and isolate and screen/monitor for sickness in new additions to household or kennel.

  • Salmonellosis is a highly contagious bacterial disease caused by many different types of the organism Salmonella. It can affect any age or breed of dog, although it is most commonly seen in young puppies and pregnant bitches. Salmonella is transmitted by contaminated water, food, or fomites (objects that can harbor transmit infection), and although it may cause severe clinical signs, individuals sometimes have no symptoms at all; Salmonella has been isolated from the feces of up to 25 percent of healthy dogs.

    Several risk factors can render an individual more susceptible to Salmonella, including their overall health status and environment; concurrent disease; administration of certain medications like corticosteroids or chemotherapy, which causes suppression of the immune system; and exposure to the organism. There are several scenarios after infection, including gastroenteritis (diarrhea, with or without blood); subtle nonspecific signs, such as lethargy, depression, anorexia, diarrhea and fever; abortion; bacteremia and endotoxemia, systemic disease due to the presence of bacteria or their toxin in the bloodstream; and asymptomatic carriage.

    Because the signs are so variable with Salmonella, many disorders must initially be considered when these individuals present. A host of infectious agents that cause gastrointestinal signs need to be differentiated from Salmonella. These include:

  • Other bacteria – Clostridium, Campylobacter, Escherichia coli, Yersinia, Bacillus piliformis, Staphylococcus

  • Viral – parvovirus, coronavirus, rotavirus, paramyxovirus, adenovirus type I, infectious canine hepatitis

  • Fungal – Histoplasma, Pythium, Aspergillus

  • Rickettsial – Salmon poisoning in the pacific northwest, Rocky Mountain Spotted Fever

  • Intestinal parasites. Roundworms, hookworms, whipworms, coccidia and Giardia are a common cause of acute diarrhea, especially in young puppies. You may or may not be able to see them in the feces.

  • Hemorrhagic gastroenteritis (HGE) is a dramatic, potentially fatal disorder with no one known cause. It has a predilection for small breed dogs and is characterized by the sudden onset of profuse bloody diarrhea and occasional vomiting.

  • Small intestinal bacterial overgrowth (SIBO) is characterized by an overgrowth of normal intestinal flora (bacteria), and may mimic salmonellosis.

  • Acute gastroenteritis is an inflammation of the lining of the stomach/intestines, and is characterized by diarrhea and/or vomiting.

  • Dietary indiscretion can include eating spoiled food, overeating, ingesting foreign material, and sudden dietary changes. It is more common in dogs than cats, due to the indiscriminate eating habits of dogs.

  • Dietary intolerance associated with particular proteins, lactose, diets high in fat, and certain food additives can cause signs similar to Salmonella.

  • Drugs and toxins can cause acute diarrhea most often by either directly irritating the lining of the intestinal tract or disturbing the normal population of bacteria. Examples include nonsteroidal anti-inflammatory drugs such as aspirin, corticosteroids, antibiotics, anti-cancer drugs, insecticides, lawn and garden products, heavy metals, and certain heart drugs (digitalis).

  • Many metabolic diseases (kidney, liver, hypoadrenocorticism, hyperthyroidism) present with clinical signs of gastrointestinal disease, including diarrhea. Diarrhea may be bloody and often is accompanied by multiple other systemic signs in these cases.

  • An intussusception (telescoping of the bowel into itself) will often cause gastrointestinal signs. It is most often associated with the presence of inflammation, foreign bodies, parasites or tumors, and commonly causes diarrhea.

  • Pancreatitis – inflammation of the pancreas – can cause a spectrum of clinical signs including severe hemorrhagic diarrhea.

  • Exocrine pancreatic insufficiency (EPI) is a disorder in which the pancreas does not produce an adequate amount of digestive enzymes. This deficiency most often results in diarrhea secondary to maldigestion (poor digestion) and malabsorption (poor absorption).

    Disorders That Cause Fever

  • Infectious disorders such as viral, bacterial, fungal, rickettsial and parasitic diseases

  • Immune or inflammatory diseases such as systemic lupus erythematosus (SLE), polyarthritis (inflammation of the joints), polymyositis (inflammation of the muscles), encephalomyelitis (inflammation of the brain and spinal cord), pancreatitis, and many others

  • Neoplasia (cancer)

    Disorders That Cause Abortion

  • Infectious disorders such as viral, bacterial, rickettsial and parasitic diseases.

  • Endocrine disorders such as hypothyroidism

  • Drug administration such as chemotherapy, hormones, certain antibiotics

  • Severe stress or trauma

  • Placental or fetal defects

  • Diagnosis In-depth

    Certain diagnostic tests must be performed for a definitive diagnosis of salmonellosis and to exclude other disease processes that may cause similar symptoms. A complete history, description of clinical signs, and thorough physical examination are all important for obtaining a diagnosis. In addition, the following tests are recommended to confirm a diagnosis:

  • Fecal studies (flotation, smear, and zinc sulfate for Giardia) should be performed on all patients with diarrhea, as intestinal parasitism is one of the most common causes diarrhea in the small animal patient. It is sometimes necessary to run multiple fecal exams, as some parasites are difficult to diagnose.

  • A complete blood count (CBC) may be within normal limits, although it may reveal anemia (low red blood cell count), and depending on the stage of disease, a decreased or elevated white blood cell count.

  • A biochemical profile helps to evaluate the kidney, liver, protein, and electrolyte status. Although often within normal limits, it is helpful to rule out other disorders that may mimic salmonellosis. Hypoglycemia (low blood sugar) may be present in those with septicemia.

  • A urinalysis helps to evaluate the kidneys and level of hydration.

  • Abdominal radiographs (X-rays) help evaluate the abdominal organs, the presence of a foreign body, or tumor. In most cases of Salmonella, there are no abnormalities detected.

  • Bacterial cultures on the feces are strongly recommended and are the only definitive means of confirming infection. It is important to know that Salmonella can be cultured from the stool of normal animals as well, so a positive culture must be interpreted in light of the particular individual and their clinical signs.

    Your veterinarian may require additional tests to ensure optimal medical care. These are selected on a case by case basis:

  • Blood cultures should be performed in those individuals suspect of having systemic infection.

  • Fecal serology, ELISA (enzyme-linked immunosorbent assay), may be helpful in diagnosing certain diseases, such as parvovirus.

  • Abdominal ultrasound may be indicated if the previous diagnostics have been inconclusive. It helps to evaluate the size, shape and integrity of the abdominal organs, and is especially helpful in evaluating for an intussusception or pancreatitis. It is a non-invasive procedure, however may require a referral facility. In cases of salmonellosis, it is usually within normal limits.

  • Serum trypsin-like immunoreactivity (TLI) is a simple blood test and is recommended in all dogs with chronic diarrhea and weight loss if the previous tests are not diagnostic.

  • Serum folate and cobalamin are blood tests, which generally increase and decrease respectively, in those cases with small intestinal bacterial overgrowth.

  • An upper gastrointestinal (GI) barium series may be considered, especially when there is concurrent vomiting. It will help rule out foreign bodies that are lucent (see through) radiographically, and other obstructive causes of acute diarrhea. It also helps evaluate for intestinal ulcers, and can assess intestinal wall thickness. It is more helpful in ruling out causes of gastroenteritis then diagnosing Salmonella. A safe dye is given to the pet by mouth, and it is watched as it travels through the GI tract. It is non-invasive, and most often able to be performed by your veterinarian, although sometimes may necessitate a referral facility.

  • Duodenoscopy or colonoscopy, which evaluates a portion of the small intestine and colon with proper instrumentation, may be indicated in some of these patients. Biopsies can be submitted for both microscopic evaluation and culture.

  • In patients who see a veterinarian for abortion, testing for Brucella, toxoplasma and herpes virus is indicated.

  • In patients who have fever as the primary clinical sign, additional diagnostics may be indicated. These include:

  • Arthrocentesis (joint taps) to rule out polyarthritis

  • Creatinine Kinase, EMGs and/or muscle biopsy to rule out polymyositis.

  • Cerebrospinal fluid tap (CSF) tap, to rule out encephalomyelitis.

    Therapy In-depth

    Appropriate therapy for canine salmonellosis varies according to the type and severity of clinical illness. Depending on the severity of clinical signs and/or stage of disease, hospitalization may or may not be recommended. Patients who are septicemic, or who have severe vomiting and/or diarrhea, fever, and or dehydration are hospitalized for aggressive treatment and stabilization. Stable patients can be treated as outpatients as long as they are monitored closely for response to therapy, and handled properly, keeping them quiet, comfortable, and most importantly, isolated. With appropriate therapy, most patients do quite well.

    It is important that all recommendations by your veterinarian are followed very closely, and any questions or concerns that arise during the treatment protocol are addressed immediately.

  • Dietary management. Placing the intestinal tract in a state of physiologic rest by dietary restriction is the single most important aspect of therapy in acute diarrhea associated with salmonellosis. Completely restricting food intake for several hours allows the intestinal tract lining to heal.

  • Food should be gradually reintroduced, starting with a bland, easily digestible and low in fat diet, feeding small, frequent meals. Examples include boiled chicken or beef, or cottage cheese as a protein source, mixed with boiled rice or potato, a carbohydrate.

  • The original diet may be gradually reintroduced over a two to three day period if the diarrhea is improving.

  • Fluid therapy may be necessary in some patients with acute diarrhea, and is directed toward correction of dehydration and acid-base derangements, replacement of electrolyte deficits, and to provide for ongoing losses.

  • Antibiotic therapy for salmonellosis is controversial. In those individuals who are healthy or have acute diarrhea, antibiotics may promote a carrier state and is contraindicated. However, they may be of benefit in animals that have hemorrhagic diarrhea, shock, fever, or sepsis. The particular antibiotic should be chosen based on the culture and sensitivity results. Enrofloxacin (Baytril®), chloramphenicol, and trimethoprim-sulfa are generally the most effective antibiotics against Salmonella.

  • Plasma transfusions may be of benefit to those critically ill patients who are septic.

  • Intestinal protectants and adsorbents, which are medications that coat, sooth and protect, are felt to aid an irritated intestinal lining.

    Follow-up

    Optimal treatment for your pet requires a combination of home and professional veterinary care. Follow-up can be critical, especially if your pet does not rapidly improve.

  • Administer all prescribed medication as directed. Alert your veterinarian if you are experiencing problems treating your pet.

  • Repeat fecal cultures monthly for several months to assess development of a carrier state.

  • Keep individuals healthy with proper nutrition, clean and disinfect your pet's environment on a regular basis, and limit excessive exposure to pounds, shelters and kennels.

  • Observe your pet's general activity level, appetite, and general demeanor and monitor for any recurrence of signs, suggestive of reinfection.

  • Remember, Salmonella is highly contagious.

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