Salmonellosis in Dogs
Dr. Bari Spielman
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.
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:
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.
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.
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.