Enterocolitis in Hamsters

Introduction

Diarrhea is the most common problem in pet hamsters. In a recent survey of two large American commercial breeding facilities, approximately 3% of shipped hamsters develop diarrhea. Diarrhea caused by enterocolitis can occur in hamsters of any age or breed and is commonly known as “wet-tail” (Fig 1). Clinical signs in weanlings usually include diarrhea, anorexia, ruffled hair, dehydration, weight loss, and death. The mortality rate is often highest in 3-10 week old hamsters, however adult hamsters may also suffer debilitating disease and death.

Figure 1. “Wet tail” or diarrhea in a hamster (Mesocricetus auratus). Photograph by Dr. Lauren Richey. Click image to enlarge.

Etiology

The cause of enterocolitis (Fig 2) may be multifactorial in hamsters, involving bacterial, parasitic, and even fungal etiologic agents. A number of the pathogens documented in hamsters are also transmissible to humans. Clinical outbreaks may be precipitated by stress, such as high temperatures or humidity, overcrowding, malnutrition, dietary changes, shipping, or underlying disease, such as endoparasitism.

Figure 2. Gross appearance of enterocolitis in a hamster (Mesocricetus auratus). Photograph provided by Dr. Lauren Richey. Click image to enlarge.

Bacteria

Historically, enterocolitis or “wet-tail” has been associated with proliferative ileitis caused by Lawsonia intracellularis, however there was no evidence of proliferative ileitis in studies by Barron et al or Motzel et al. Other bacteria that have been implicated in “wet-tail include Clostridium spp., E. coli, Campylobacter jejuni, Helicobacter aurati, Salmonella spp., and Pasteurella pneumotropica. In a recent survey of two large American commercial breeding facilities, the most clinically significant infections were with species of Campylobacter and Clostridium. Clostridium piliforme is a gram-negative, spore-forming, obligate intracellular bacterium and the causative agent of Tyzzer’s disease. Clostridium difficile has also been associated with enterotoxemia, typhlitis and enteritis in hamsters (Fig 3).

Figure 3. Histologic appearance of Tyzzer’s disease in a hamster (Mesocricetus auratus). Photograph provided by Dr. Lauren Richey. Click image to enlarge.

Parasites

Concurrent mild to severe infections with the tapeworm, Hymenolepis nana, are very common in hamsters with bacterial enterocolitis (Fig 4).  As the degree of disease and debilitation increase, so does the tapeworm burden. In some individuals, the tapeworm load is high enough to nearly obstruct the intestines. The protozoa Giardia, Entamoeba, Spironucleus muris, and trichomonads are also variably found in affected individuals.

Figure 4. Gross appearance of the tapeworm, Hymenolepsis nana, from a hamster (Mesocricetus auratus). Photograph provided by Dr. Lauren Richey. Click image to enlarge.

Fungal

The yeast Torulopsis sp. (Candida sp.) can heavily colonize the stomach of hamsters.

Control

Prevention and treatment of “wet’-tail” has historically centered around antimicrobials, husbandry practices, selective breeding, and culling. Unfortunately this approach is rarely rewarding because of the intracellular nature of C. piliformeand the acute progression of Tyzzer’s disease.

Bacterial spores are quite stable and can remain infectious for 1 to 2 years. Control of enterocolitis in a commercial breeding facility would ideally involve depopulation, rigorous disinfection, and repopulation with C. piliforme-free breeding stock.

Care of the individual patient relies upon antibiotic therapy and supportive care. Begin oral antibiotics such as sulfa-trimethoprim (Bactrim®, Roche) at 30 mg/kg PO q12h or enrofloxacin (Baytril®, Bayer) 5-10 mg/kg PO q12h. Depending on the clinical status of the patient, subcutaneous fluids and nutritional support may also be indicated.

Theorizing that high worm burdens make the gut more vulnerable to bacterial infection, Barron et al treated weanling hamsters with praziquantel (Droncit®, Bayer) 20 mg/kg PO, repeat in 10d and fenbendazole (Panacur®, Hoechst) 20 mg/kg PO q24h x 5d prior to shipping. (Note: Napa Nectar™ Plus is a useful and easy way to administer fenbendazole to large hamster colonies). Unfortunately this treatment regimen made no significant difference when compared to control animals.

Summary

“Wet-tail” is a non-specific clinical sign that can result from enterocolitis and resultant diarrhea in pet hamsters. Unfortunately enterocolitis is the most important cause of morbidity and mortality in hamsters. The cause of enterocolitis may be multifactorial in hamsters of all ages and may include bacteria such as Clostridium spp. and Campylobacter jejuni and parasites, particularly Hymenolepis nana. Clinical outbreaks of diarrhea in hamsters may be precipitated by stress, including high temperatures or humidity, overcrowding, malnutrition, dietary changes, shipping, or underlying diseases, such as endoparasitism. Prevention and treatment of “wet’-tail”, which centers around the use of antimicrobials, husbandry practices, selective breeding, and culling, have generally proved unrewarding.

Acknowledgement: I thank Dr. Lauren Richey who was instrumental in the study referenced below (Barron et al) and who also provided the photographs provided above.

References