Veterinarians: Are you overanalyzing your fecal exams?

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Question: Fecal examination results from a 20-week-old spayed female kitten revealed soft, unformed feces with steatorrhea (of 1 week's duration) and a moderate amount of spirochete bacteria.

The cat is otherwise asymptomatic and is current on vaccinations and anthelmintic administration. It was adopted at about 12 weeks of age from a household where the queen and kittens had indoor and outdoor access and minimal veterinary care. An ovariohysterectomy was performed at 14 weeks of age. The cat's body condition score is 5 of 9 and no weight loss has occurred. The owner had recently added a high-quality canned food meal as a treat once a day but has since discontinued it.

Do these spirochetes indicate bacterial overgrowth in the stomach or small intestine? Should I begin treatment for possible Helicobacter pylori or Campylobacter infection?

Answer: Fecal testing can be simple, convenient and affordable when evaluating animals with chronic diarrhea, but sometimes we need to be cautious about over-interpreting what we see. In this case, it is difficult to determine the clinical relevance of spiral bacteria in a stool sample, as these can be an incidental finding in many cats with and without diarrhea.

This kitten has a history of being in a multicat environment with minimal preventive care, presenting with acute diarrhea (less than 2 weeks' duration). On initial evaluation prior to fecal analysis, my top differentials would be infectious etiologies (i.e. intestinal parasites or viral disease); however, food allergy would also have to be a consideration as it can affect animals of all ages. 

The finding of steatorrhea means I'd keep exocrine pancreatic insufficiency (EPI)-although rare in a young cat-on the differential list as well. A fecal flotation to investigate for intestinal parasites would be the first step, especially if the patient's deworming status is unknown. To investigate for possible bacterial overgrowth, fecal cytology could be performed, as it was in this cat. 

The presence of a moderate amount of spirochete bacteria on fecal cytology would not be enough evidence for targeted treatment of a specific disease. Numerous spirochete bacteria exist within the gastrointestinal (GI) tract of both healthy and sick cats, and the appearance can be very similar among different types. 

One example mentioned in the question is Helicobacter, a bacterium most commonly isolated to the stomach of both sick and healthy dogs and cats. Helicobacter is rarely identified in significant quantities in the stools, and even in high concentration in the stomach (where it most commonly resides) may not be indicative of clinical disease. Additionally, for this patient, the most common presentation of an animal with a Helicobacter infection is chronic vomiting, so that would not be a consideration for this case. 

Campylobacter, another common spirochete bacterium seen in cats that can be associated with acute diarrhea, can also be seen in healthy cats as an incidental finding. As a result, observation of spirochete bacteria in the stool alone is not enough to confirm a diagnosis.

Given that the cat has clinical signs consistent with GI disease, I would recommend submitting a fecal sample for a diarrhea polymerase chain reaction (PCR) panel to investigate for the presence of a causative agent. While this test cannot confirm cause and effect (that is, it's not uncommon to see an incidental false positive) it will help to determine whether the spirochete bacteria seen are Campylobacter. 

Pending results of the PCR, the cat should be started on nonspecific therapy including oral metronidazole (12 mg/kg q12h) and a bland diet, as well as an additional broad-spectrum dewormer such as fenbendazole. If PCR results confirm Campylobacter, then consider either oral azithromycin or tylosin; if the PCR is negative and the cat is not responding to conservative therapy, then additional diagnostics should be considered, including baseline blood work and a GI malabsorption panel that includes trypsin-like immunoreactivity (to further investigate for exocrine pancreatic insufficiency as a cause for the steatorrhea). 

Scott Owens, DVM, MS, DACVIM (SAIM) is a board-certified small animal veterinary internal medicine specialist at MedVet Indianapolis, where he has been part of the medical team since 2015.