SYRIAN HAMSTERS: Viral, Parasitic, Bacterial and Noninfectious Diseases

HAMSTERS

• More likely to bite• Signs of an angry

hamster– Roll on back– Stand on hind

limbs– Vocalizing

VIRUSES

• Compared with laboratory mice, relatively few naturally acquired viral infections have been reported for the Syrian hamster. However, Syrian hamsters can be infected with several of the viruses that infect laboratory mice and rats.

• In most cases, viral infections in Syrian hamsters are subclinical—there is no overt disease.

• Most viral infections in Syrian hamsters are poorly described, unlike similar infections in laboratory mice and rats

Sendai and pneumonia viruses

• Two respiratory viruses, Sendai virus and pneumonia virus of mice (PVM), have been shown by serologic surveys to commonly infect laboratory hamsters These RNA viruses are of the family Paramyxoviridae.

• These viral infections involve both the upper and lower respiratory system and are spread by direct contact with nasal secretions and aerosol in rats and mice

Diagnosis & Control

• Diagnosis of Sendai virus or PVM infection is made by testing sera for specific antiviral antibodies in either an enzyme-linked immunosorbent assay (ELISA) or indirect immunofluorescent antibody (IFA).

• Control Both Sendai virus and PVM infection can be eliminated from a hamster population by isolating the animals and letting the infection run its natural course

LCMV

• Lymphocytic choriomeningitis virus (LCMV), an arenavirus of the wild house mouse, can infect hamsters, monkeys, dogs, guinea pigs, rabbits, chickens, and people. Both pet and laboratory hamsters have been shown to harbor the virus. Naturally-occurring LCMV infection of hamsters is chronic, persistent, usually subclinical, and characterized by prolonged viral excretion in the urine

LCMV

• LCMV is a serious zoonotic agent. It can be spread from hamsters to people both by aerosol and by direct contact. Outbreaks in people have occurred from contact with infected pets as well as laboratory hamsters.

• Symptoms in humans- Infection in people may be either subclinical or clinical with symptoms including fever, headache, myalgia, nausea, vomiting, sore throat, and photophobia

Bacterial Diseases

Tyzzer’s Disease

• Occasionally reported in hamsters and other rodent species, Clostridium piliforme

• Clinical signs:anorexia, dehydration, watery diarrhea, and sudden death.

• See mice info..

C piliforme

Clostridial Enteritis

• Enteric disease associated with variable morbidity and mortality may result from overgrowth of Clostridium perfringens, C. difficile, and perhaps C. spireforme.  These anaerobic bacteria produce toxins that cause edema and hemorrhage, and occasionally mucosal dysfunction and  necrosis. 

Clostridial enteritis manifests as 2 syndromes.

• The first is acute diarrheal disease in hamsters with cecal bacteria dysbiosis from dietary changes, antibiotic therapy, concurrent diseases or other physiologic stressors that can disrupt the cecal microbiota.

• The second syndrome occurs in older (>6 mo) hamsters usually on experimental studies that often do not involve changes in diet or oral medication.  Hamsters slowly lose weight and die without developing diarrhea.  Gross lesions include mild dehydration and thickening of the cecal wall with thick to watery cecal contents

Clostridial enteritis

Colibacillosis

•   1.  Etiology:  E. coli recovered from hamsters with colibacillosis has virulence factors that allow for adherence to mucosal cells and production of enterotoxins or invasion.  The incidence of disease is moderate.

•   2. Transmission:  The disease is transmitted via direct contact, fecal-oral and fomite contamination.

•   3. Predisposing Factors:  A high carbohydrate or vitamin imbalanced diet, exposure to infected animals, shipment stress, overcrowding, and lack of fresh water are stressful events that precipitate disease

Clinical Signs

• Generally the disease is acute in onset, with 2- to 4-week-old hamsters developing a profuse yellow watery diarrhea that mats the area around the tail.  Dehydration and death quickly ensues. 

Diagnosis:  Culture of the gut with recovery of pure culture of E. coli is strong evidence for disease. 

Treatment:   Supportive treatment for dehydration with lactated Ringer's solution given SQ (5% to 15% of body weight) and Kaopectate (1-2 ml PO) for diarrhea may be effective.  Antimicrobial therapy may actually worsen the bacterial population imbalance and lead to development of a fatal enteritis.

Control:  Even though colibacillosis outbreaks are generally associated with stress every effort should be made to prevent cage to cage transmission of feces.  Strict sanitation practices.

Salmonellosis

Etiology:  Salmonella enterica serovars Typhimurium and Enteritidis are Gram-negative, invasive enteric bacteria.  Incidence of infection and disease is low.

Transmission:  Food, water and bedding may be contaminated by infected feces from wild rodents.

Clinical Signs:  The disease may only be manifest as acute death. Clinical signs are seen primarily in pregnant or recently delivered females and infant or weanling hamsters.  Diarrhea is usually not present but pregnant females may abort and become cachexic.

Parasites

Hamsters can harbor several different endo- and ectoparasites. The commonly seen protozoa, pinworm, tapeworm, and mite infestations.

Protozoa• Spironucleus muris (left photo), Giardia sp.,

Tritrichomonas sp., and Entamoeba sp. (right photo) are protozoa which commonly inhabit the small and large intestine without causing clinical signs.  When the luminal contents become more fluid, as in the case of bacterial enteritis, these protozoa take advantage of the opportunity to replicate, and frequently aggravate the inflamed intestinal tract

Pinworms• Etiology:  Syphacia mesocricetus is the hamster

pinworm (see photo).  Syphacia obvelata and Syphacia muris are also capable of infecting hamsters.  Prevalence of a pinworm infection is low, however the incidence of parasitism within individual colonies may be high.

Pinworms

• Transmission:  Syphacia  sp. deposit eggs in the perianal region.  Transmission of infection occurs via ova ingestion. 

• Clinical signs:  No signs are usually seen.  Heavy parasite loads may lead to rectal prolapse or perianal irritation.

•  Gross Pathology:  Pinworms are easily recognized as white hair-like nematodes in the cecum.

• Diagnosis:  Direct exam of cecal contents to identify adult worms, and fecal flotation, and perianal tape test for ova (see photo) are routinely used diagnostic methods. 

Treatment & Control 

• If treatment is desired, two doses of piperazine (10 mg/ 1ml water) for 7 days followed by 5 days without treatment is effective.  Thiabendazole at 0.1% in the feed for 3 to 4 weeks is also effective. 

• Rigid sanitary procedures, and use of filter hoods should be employed to prevent aerosol transmission.  Regular ova examinations with treatment may control the parasitism.

Mange Mites

•  Etiology:  Demodex criceti and Demodex aurati are mange mites of hamsters.  High incidence of infestation occurs without clinical signs.  The mites are generally found together. Demodex criceti is considered non-pathogenic and is found in the epidermis. Demodex aurati, the more pathogenic mite, is found in the pilosebaceous component of the skin

• Transmission:  Demodex infestations are thought to be spread by direct contact.

• Predisposing factors are considered necessary for the development of clinical signs including malnutrition, concurrent systemic disease, and age

Clinical Signs

• Clinical signs can range from none to alopecia, dry, scaly, scabby dermatitis, and rough hair coat.  Alopecia generally occurs over the rump and back.

Demodicosis

Alopecia

Dermatitis

Alopecia

Diagnosis

• Diagnosis:  Skin scrapings of alopecia skin will reveal mites. Demodex criceti has a shorter body length and is scraped from epidermal pits (A.).  Demodex aurati is longer that Demodex criceti, and is squeezed from the hair follicles (B.).

Do you know my name ?

Miscellaneous Maladies

Antibiotic-associated Enterocolitis

• Administration of antibiotics selective for gram-positive bacteria such as lincomycin, clindamycin, ampicillin, vancomycin, erythromycin, gentamicin, penicillin, and cephalosporins may cause a fatal enterotoxemia with profuse diarrhea and high mortality within 2-10 days.

Proliferative Enteritis (“wet tail”)

• Proliferative enteritis is a frequent cause of diarrhea in hamsters.

• Recently, the causative agent was determined to be identical to Lawsonia intracellularis , a bacteria that causes proliferative enteritis in swine.

• Precipitating factors include recent transport, overcrowding, surgery, and dietary changes

Proliferative Enteritis (“wet tail”)

• Clinically, it is more common in younger hamsters with sudden onset, high morbidity and mortality, and signs of watery diarrhea and matting of fur around the tail and ventral abdomen.

• Transmission is by the fecal-oral route.

• Gross pathology may include ileal thickening, enlarged mesenteric lymph nodes, peritonitis, and abdominal adhesions.

Hyperemic ileum

Treatment

• Treatment includes supportive fluids (oral electrolyte solutions or lactated Ringer’s solution, SC) for dehydration (5-15% body wt), 1-2 mL bismuth subsalicylate, PO, and appropriate antibiotics such as enrofloxacin, metronidazole, or trimethoprim-sulfa, which can be administered via the drinking water

Amyloidosis

• Amyloidosis is a condition whereby proteins produced by the body are deposited in various organs, primarily the liver and kidneys.

• Kidney and liver failure

Amyloidosis

Malocclusion

Neoplasia• Lymphosarcoma• Adrenal cortex tumors• Malignant melanoma