Yersiniosis

Yersiniosis in guinea pigs is a serious bacterial infection caused primarily by Yersinia pseudotuberculosis, a gram-negative bacterium that affects the gastrointestinal system and associated lymph nodes, frequently progressing to systemic disease involving multiple organs. This infection, sometimes called pseudotuberculosis due to the tubercle-like nodules it forms in affected organs, is one of the most significant bacterial diseases affecting guinea pig colonies and carries high mortality rates even with treatment. The disease is zoonotic, meaning it can spread from guinea pigs to humans, adding public health considerations to the clinical management of affected animals and colonies.

Yersiniosis occurs sporadically in pet guinea pigs but can cause devastating outbreaks in breeding facilities, pet stores, and rescue organizations where animals are housed in close proximity and stress levels may be elevated. The bacteria are typically introduced through contaminated food, water, or bedding, often originating from wild rodents, birds, or their droppings. Guinea pigs are exquisitely sensitive to Yersinia infection, with exposure frequently resulting in clinical disease rather than asymptomatic carriage. The combination of high susceptibility and environmental persistence of the organism makes control of outbreaks challenging once a colony becomes contaminated.

The impact of yersiniosis on guinea pig health is severe, with the disease frequently fatal even in animals receiving veterinary care. The infection typically begins in the gastrointestinal tract, causing enteritis with diarrhea and weight loss, but rapidly spreads to mesenteric lymph nodes and then systemically to the liver, spleen, and lungs. Affected organs develop characteristic caseous nodules that impair function and serve as ongoing sources of bacterial dissemination. Guinea pigs with yersiniosis experience significant suffering from gastrointestinal symptoms, systemic illness, and multi-organ dysfunction, making this a serious welfare concern.

Early detection offers the best chance of survival, but the prognosis for clinical yersiniosis in guinea pigs remains guarded to poor even with aggressive antibiotic therapy and supportive care. The zoonotic nature of this disease requires implementation of strict hygiene protocols when caring for infected or potentially infected animals, and households with immunocompromised individuals, young children, elderly persons, or pregnant women must carefully consider the risks of attempting treatment versus humane euthanasia. Prevention through excellent husbandry, protection from wild animal contamination, and proper quarantine of new animals is essential for protecting guinea pig colonies from this devastating disease.

The primary cause of yersiniosis in guinea pigs is infection with Yersinia pseudotuberculosis, a gram-negative coccobacillus belonging to the Enterobacteriaceae family. Less commonly, Yersinia enterocolitica may also cause disease in guinea pigs, though Yersinia pseudotuberculosis is the predominant pathogen. These bacteria are environmental organisms found in soil, water, and vegetation contaminated by the feces of wild animals including rodents, rabbits, and birds that serve as reservoir hosts. Guinea pigs become infected primarily through ingestion of contaminated food, water, or bedding materials, with the fecal-oral route being the primary means of transmission.

While yersiniosis is not a hereditary condition, individual guinea pig susceptibility to infection may be influenced by genetic factors affecting immune function. Guinea pigs are considered highly susceptible hosts for Yersinia pseudotuberculosis compared to many other species, suggesting species-level genetic factors that make them particularly vulnerable. Within guinea pig populations, animals with compromised immune systems due to genetic factors, concurrent illness, nutritional deficiencies, or chronic stress are significantly more likely to develop severe disease when exposed. Young guinea pigs with immature immune systems are at especially high risk.

Environmental factors play a crucial role in the introduction and transmission of Yersinia within guinea pig populations. Contamination of hay, vegetables, pellets, or bedding with wild animal droppings introduces the pathogen to the guinea pig environment. Inadequate storage of food and bedding materials in areas accessible to wild rodents or birds facilitates contamination. Cool, moist conditions favor Yersinia survival in the environment, with the bacteria capable of persisting for extended periods in contaminated materials. Once introduced to a guinea pig colony, the organism spreads through fecal shedding by infected animals, contaminating the shared environment and exposing cage mates.

Multiple risk factors significantly increase the likelihood of guinea pigs developing clinical yersiniosis. Stress from any source including overcrowding, transportation, environmental changes, concurrent illness, and improper handling suppresses immune function and increases susceptibility to infection and disease progression. Vitamin C deficiency, extremely common in guinea pigs, severely compromises immune function and increases vulnerability to all infectious diseases. Poor sanitation with infrequent bedding changes allows environmental bacterial loads to build up. Feeding unwashed vegetables or hay contaminated during growing, harvesting, or storage introduces the pathogen. Cold stress during winter months may increase susceptibility, as Yersinia grows well at cooler temperatures.

The mechanism of yersiniosis involves oral ingestion of bacteria, colonization of the intestinal tract, invasion of the intestinal epithelium, and spread to regional lymph nodes and beyond. After ingestion, Yersinia bacteria attach to and invade the intestinal epithelial cells, particularly in the ileum and cecum, triggering an inflammatory response that causes enteritis with diarrhea. The bacteria spread through lymphatic drainage to the mesenteric lymph nodes, where they multiply and cause characteristic granulomatous inflammation with caseous nodule formation. From the lymph nodes, bacteria enter the bloodstream and seed distant organs including the liver, spleen, and lungs, where similar nodules develop. The progressive multi-organ involvement and ongoing systemic infection explain the high mortality rate despite treatment.

Early warning signs of yersiniosis in guinea pigs are often subtle and may be overlooked until disease has progressed to a serious stage. As prey animals, guinea pigs instinctively hide signs of illness to avoid appearing vulnerable, making early detection challenging even for attentive owners. Initial signs may include slightly decreased appetite, subtle reduction in activity levels, mild weight loss, or minor changes in fecal consistency. Some guinea pigs may show ruffled fur indicating general malaise before more specific symptoms develop. The insidious onset means that by the time obvious clinical signs appear, the infection has often already spread beyond the gastrointestinal tract.

As infection progresses, more recognizable gastrointestinal symptoms develop that should prompt immediate veterinary attention. Diarrhea is a common finding, ranging from soft, poorly formed stools to watery or mucoid diarrhea that can rapidly lead to dehydration. Weight loss becomes more pronounced as both decreased appetite and malabsorption from intestinal damage combine to produce wasting. Affected guinea pigs may show abdominal discomfort, reluctance to move, or hunched posture indicating internal pain. Decreased fecal output may occur as gastrointestinal function deteriorates, and any cessation of fecal production indicates dangerous gastrointestinal stasis requiring emergency attention.

Behavioral changes in guinea pigs with yersiniosis reflect both gastrointestinal distress and systemic illness from widespread infection. Affected animals become progressively lethargic, spending increased time hiding or lying in one spot rather than engaging in normal activities. Appetite continues to decline, and guinea pigs may completely refuse food including favorite treats. They typically stop vocalizing, including the characteristic wheeking sounds associated with feeding time excitement. Reduced grooming results in a rough, unkempt coat appearance. Social interaction with cage mates and human caregivers decreases as the guinea pig withdraws into illness.

Physical examination findings in guinea pigs with yersiniosis reveal multiple abnormalities depending on disease stage and extent of organ involvement. Palpation of the abdomen may reveal enlarged mesenteric lymph nodes as distinct masses, along with possible hepatomegaly and splenomegaly from organ involvement. The fur is typically dull and may be soiled around the hindquarters from diarrhea. Dehydration is common, evidenced by skin tenting and tacky mucous membranes. Body condition score is often poor with visible weight loss. Fever may be present but can be difficult to detect without proper equipment. In advanced cases, respiratory signs may develop from lung involvement.

Symptom progression in yersiniosis is often rapid once clinical disease becomes apparent, with guinea pigs deteriorating significantly over days to a week or two. What begins as gastrointestinal illness progresses to systemic disease as bacteria spread throughout the body. Multiple organ involvement causes compound symptoms including respiratory compromise from lung lesions, potential jaundice from liver involvement, and general systemic illness from widespread infection. Some guinea pigs develop a chronic form with prolonged wasting and intermittent symptoms, though this is less common than acute progressive disease.

Emergency symptoms requiring immediate veterinary care include severe watery or bloody diarrhea, complete cessation of eating and drinking, complete absence of fecal production indicating gastrointestinal stasis, severe lethargy or collapse, difficulty breathing, distended or obviously painful abdomen, and any signs of septic shock including pale or blue-tinged mucous membranes, cold extremities, or collapse. Guinea pigs showing these signs are critically ill and may die within hours without aggressive intervention. Even with emergency care, prognosis for advanced yersiniosis remains poor.

Diagnosis of yersiniosis in guinea pigs begins with a thorough examination by a veterinarian experienced with exotic species and cavy medicine specifically. The veterinarian will obtain detailed history including information about diet sources, potential exposure to wild animal contamination, recent introductions of new animals, other sick guinea pigs in the colony, and timeline of symptom development. Physical examination focuses on assessment of hydration status, abdominal palpation to detect enlarged lymph nodes or organomegaly, evaluation of body condition and weight loss, and overall assessment of illness severity. The combination of gastrointestinal symptoms, wasting, and palpable abdominal masses in a guinea pig strongly suggests yersiniosis.

Diagnostic testing for yersiniosis involves multiple laboratory evaluations to identify the causative organism and assess disease extent. Bacterial culture from feces, blood, or tissues provides definitive diagnosis when Yersinia pseudotuberculosis is isolated. Fecal culture may be positive in animals shedding the organism, though intermittent shedding can cause false negative results. Blood cultures may be positive in cases of septicemia. Post-mortem culture from affected organs including liver, spleen, and mesenteric lymph nodes is often diagnostic in fatal cases. Serological testing detecting antibodies against Yersinia may support diagnosis but is not routinely available for guinea pigs.

Differential diagnosis for guinea pigs presenting with gastrointestinal symptoms, weight loss, and abdominal masses includes several other conditions. Salmonellosis causes similar gastrointestinal symptoms and systemic illness, with differentiation requiring bacterial culture. Tyzzer's disease caused by Clostridium piliforme affects guinea pigs with acute fatal enteritis. Other bacterial enteritides including Escherichia coli and Clostridium difficile cause diarrhea and systemic illness. Intestinal parasitism including coccidiosis can cause diarrhea and wasting. Abdominal lymphoma or other neoplasia may cause similar abdominal masses and systemic illness. Antibiotic-associated dysbiosis causes severe enteritis in guinea pigs given inappropriate antibiotics.

Once yersiniosis is suspected or confirmed, additional testing helps assess disease extent and provides prognostic information. Complete blood count often reveals elevated white blood cell counts with increased heterophils indicating bacterial infection, though severely ill animals may show depressed counts. Blood chemistry panels assess liver and kidney function, which may be compromised with organ involvement. Radiographs may reveal hepatomegaly, splenomegaly, or pulmonary nodules in advanced cases. Ultrasound examination provides more detailed evaluation of abdominal organs and lymph nodes. In colonies where yersiniosis is diagnosed, all contact animals should be considered potentially infected and monitored closely, with fecal cultures obtained to identify shedders.

Emergency treatment for guinea pigs with suspected or confirmed yersiniosis focuses on aggressive supportive care to address immediate life-threatening complications while initiating antimicrobial therapy. Fluid therapy is essential to correct dehydration and maintain hydration, typically administered subcutaneously or intravenously depending on severity. Nutritional support through assisted syringe feeding with critical care formulas maintains gut function and provides essential calories, as gastrointestinal stasis is an emergency in guinea pigs. Pain management with guinea pig-safe analgesics addresses abdominal discomfort. Warming support may be needed for hypothermic animals. Critically ill guinea pigs require intensive monitoring and may deteriorate rapidly despite intervention.

Medical management with appropriate antibiotics forms the core of yersiniosis treatment, but antibiotic selection in guinea pigs requires extreme caution. Guinea pigs are obligate hindgut fermenters with a delicate intestinal microbiome, and many commonly used antibiotics are absolutely contraindicated and potentially fatal. Antibiotics that must never be given to guinea pigs include penicillins, ampicillin, amoxicillin, cephalosporins, clindamycin, lincomycin, and erythromycin. Yersinia pseudotuberculosis is typically susceptible to fluoroquinolones, aminoglycosides, trimethoprim-sulfonamides, and chloramphenicol. Enrofloxacin is often the antibiotic of choice due to its safety profile in guinea pigs and activity against Yersinia. Treatment must be prolonged, typically four to six weeks minimum, due to the intracellular nature of the infection.

Surgical intervention has limited role in treating yersiniosis due to the disseminated nature of the infection by the time clinical signs are apparent. Unlike localized abscesses that can be excised, the multiple nodules throughout the liver, spleen, lymph nodes, and potentially other organs cannot be surgically addressed. Surgery may occasionally be considered for diagnostic purposes, such as biopsy of affected organs when diagnosis is uncertain, but does not provide therapeutic benefit. Treatment relies primarily on antimicrobial therapy and supportive care rather than surgical approaches.

Supportive care measures are critical for any chance of survival and require intensive, prolonged nursing care. Assisted feeding must continue every two to four hours for guinea pigs not eating adequately on their own, using herbivore critical care formulas. Vitamin C supplementation at elevated doses supports immune function during the prolonged illness and recovery period. Fluid supplementation continues as needed to maintain hydration. Probiotic supplementation may help maintain gut flora during antibiotic treatment. Housing should be warm, clean, and stress-free. Continued pain management supports comfort and appetite.

Alternative and complementary treatments may support conventional therapy but cannot replace appropriate veterinary care and antibiotic treatment for this serious infection. Ensuring the guinea pig remains warm and comfortable reduces physiological stress. Gentle abdominal massage may help with gut motility in recovering animals. Maintaining visual contact with bonded companions while keeping them separated reduces stress from isolation. Herbal appetite stimulants approved by the veterinarian may encourage voluntary food intake. Immune support supplements may be considered but have limited evidence in this context.

Treatment decisions for yersiniosis must carefully weigh multiple factors including the zoonotic nature of the disease, poor prognosis despite treatment, and household safety considerations. The guarded to poor prognosis even with aggressive treatment means many guinea pigs will not survive despite veterinary intervention. The zoonotic risk requires strict hygiene protocols, and households with immunocompromised individuals, young children, elderly persons, or pregnant women face additional risk considerations. The cost of intensive treatment over potentially weeks to months, combined with uncertain outcomes, should be discussed honestly. Humane euthanasia may be the most appropriate choice in severe cases or when household safety cannot be assured.

Recovery from yersiniosis in guinea pigs is a prolonged process that requires weeks to months of treatment and monitoring, assuming the animal survives the initial acute phase of illness. Guinea pigs that survive the first one to two weeks of treatment and show clinical improvement have better chances of eventual recovery, though the intracellular nature of Yersinia infection means bacteria can persist in tissues despite apparent clinical improvement. Resolution of diarrhea, return of appetite, stabilization of weight, and improved activity levels indicate positive treatment response. Complete elimination of the bacteria is difficult to confirm and may never be fully achieved in some survivors.

Post-treatment care for recovering guinea pigs requires continued vigilance and potentially ongoing management. Antibiotic therapy typically continues for a minimum of four to six weeks, and some veterinarians recommend even longer courses given the tendency for relapse. Assisted feeding may be needed for extended periods until the guinea pig consistently maintains weight through voluntary food intake. Vitamin C supplementation should continue at elevated doses throughout recovery and long-term. Follow-up veterinary examinations assess clinical progress and monitor for complications or relapse. Fecal cultures may be obtained to assess ongoing bacterial shedding, though interpretation is complicated by intermittent shedding patterns.

Prognosis for guinea pigs with yersiniosis is guarded to poor overall, though outcomes vary based on several factors. Guinea pigs diagnosed early before extensive systemic spread have better survival chances than those with advanced multi-organ involvement. Overall health status and immune function prior to infection influence outcome. Response to initial treatment within the first week provides prognostic information, with guinea pigs that stabilize and improve having better chances than those that continue to decline. Even with aggressive treatment, mortality rates for clinical yersiniosis in guinea pigs are high, often exceeding 50 to 70 percent.

Long-term outlook for surviving guinea pigs requires understanding of the chronic nature of this infection. Some guinea pigs make apparent clinical recovery but continue to harbor bacteria in tissues, with potential for relapse during periods of stress or immune compromise. Survivors may have residual organ damage from the nodules that formed during acute infection, potentially affecting liver, spleen, or lung function. Chronic carriers pose ongoing infection risk to other guinea pigs and potentially to humans, requiring continued attention to hygiene. Recovered guinea pigs should be considered potentially infectious and managed accordingly, with owners accepting the ongoing responsibilities this entails.

Primary prevention of yersiniosis in guinea pigs centers on preventing introduction of the pathogen through contaminated food, water, or bedding. All hay, pellets, and bedding should be stored in sealed containers inaccessible to wild rodents, birds, and other animals that may carry Yersinia and contaminate supplies with their droppings. Food storage areas should be inspected regularly for evidence of wild animal intrusion. Fresh vegetables should be washed thoroughly before feeding, with organic produce from known clean sources preferred. Water should be provided fresh daily from clean sources. Any supplies showing evidence of contamination, moisture damage, or pest access should be discarded rather than fed.

Environmental prevention strategies focus on protecting guinea pigs from exposure to wild animal vectors and maintaining sanitary conditions. Housing should be secured against wild rodent entry, with attention to gaps around doors, windows, and utility penetrations. Guinea pigs should not be housed in areas where wild birds have access or where wild bird droppings may contaminate the environment. Outdoor housing for guinea pigs is particularly risky due to exposure potential and should include barriers against wild animal contact. Indoor housing is safer when wild animal exclusion is maintained. Cage cleaning with appropriate disinfectants reduces environmental bacterial loads.

Quarantine protocols are essential for preventing introduction of yersiniosis into established guinea pig populations. All new guinea pigs should be quarantined for a minimum of three to four weeks in a completely separate area before introduction to resident animals. New animals should be monitored carefully for any signs of illness during the quarantine period, particularly diarrhea, weight loss, or declining condition. Fecal cultures from quarantine animals before introduction can identify shedders, though negative results do not guarantee freedom from infection. Any animal showing signs of illness during quarantine should remain isolated and receive veterinary evaluation.

Nutrition and immune support help guinea pigs resist infection when exposed. Proper nutrition including unlimited timothy hay, appropriate pellets, and daily fresh vegetables provides the foundation for healthy immune function. Vitamin C supplementation is absolutely essential, providing 25 to 50 milligrams daily for healthy adults, as deficiency severely compromises immunity. Stress reduction through stable environments, gentle handling, appropriate social groupings, and avoiding overcrowding supports immune function. Maintaining overall health through regular veterinary care and prompt attention to any illness keeps guinea pigs in optimal condition to resist infection.

Early intervention strategies help contain potential outbreaks and protect colonies when yersiniosis is suspected or confirmed. Any guinea pig showing diarrhea, weight loss, or declining condition should be isolated immediately pending veterinary evaluation. If yersiniosis is diagnosed, all contact animals should be considered exposed and monitored closely. Environmental decontamination with appropriate disinfectants may help reduce bacterial loads. Investigation of potential contamination sources including food, bedding, and water helps identify and eliminate ongoing exposure. Necropsy of guinea pigs that die should be performed to identify infectious causes and prompt protective measures for remaining animals.

Daily management of guinea pigs with active yersiniosis requires intensive nursing care, strict isolation, and attention to both the animal's needs and zoonotic safety considerations. Infected guinea pigs must be housed completely separately from healthy animals, ideally in a different room with separate ventilation. All care for infected animals should be performed after caring for healthy guinea pigs, never before, with thorough handwashing and ideally dedicated clothing between groups. Medication administration, assisted feeding, and monitoring must occur on a consistent schedule. Detailed records of food intake, fecal output, weight, and clinical status help track response to treatment and guide veterinary adjustments.

Home environment modifications for guinea pigs with yersiniosis prioritize infection control, cleanliness, and supportive conditions. Housing should be simple and easy to clean thoroughly, with fleece liners or paper-based bedding that can be changed frequently and disposed of safely. Cage and accessories should be cleanable with disinfectants effective against Yersinia. The area should be easily isolated from other pets and family activities. Temperature should be kept comfortable and stable to reduce physiological stress. Waste materials including bedding, uneaten food, and feces should be bagged and disposed of appropriately, with consideration given to preventing environmental contamination.

Quality of life considerations must be balanced against realistic assessment of prognosis when managing guinea pigs with yersiniosis. Pain management through appropriate medications improves comfort and may encourage eating. Providing favorite foods within dietary appropriateness gives the guinea pig something positive. Gentle interaction and quiet companionship from the caregiver provides social contact while maintaining safety precautions. The guinea pig's quality of life should be honestly assessed on an ongoing basis, and if suffering cannot be adequately managed or clinical status continues to decline despite treatment, humane euthanasia may be the most compassionate option.

Ongoing monitoring requirements for guinea pigs being treated for yersiniosis are intensive and extend well beyond apparent clinical recovery. Daily assessment of appetite, activity, fecal production, and overall demeanor identifies changes requiring veterinary attention. Regular weighing, ideally daily during acute illness and at least weekly during recovery, provides objective data on treatment response. Any recurrence of diarrhea, weight loss, or declining condition may indicate treatment failure or relapse requiring veterinary consultation. Long-term survivors require ongoing monitoring for potential relapse, particularly during periods of stress.

Caregiver support and education are essential given the serious nature of yersiniosis and the demands of treatment. Understanding the zoonotic risk and implementing appropriate protective measures is critical for family safety. Household members should know the symptoms of human yersiniosis, which include fever, abdominal pain, and diarrhea, and seek medical attention promptly if symptoms develop. The emotional challenges of caring for a critically ill pet with uncertain prognosis while managing infection control concerns should be acknowledged. Caregivers should have realistic expectations about outcomes and be prepared for the possibility of their guinea pig not surviving despite best efforts. Support from exotic pet communities and veterinary staff helps manage the stress of this demanding situation.

Yersiniosis does not demonstrate significant breed predisposition in guinea pigs, as susceptibility is primarily determined by exposure, stress levels, immune status, and environmental factors rather than genetic background. All guinea pig breeds including American, Abyssinian, Peruvian, Silkie, Teddy, Texel, and others are equally susceptible to Yersinia pseudotuberculosis infection when exposed to contaminated materials. Guinea pigs as a species are highly susceptible hosts for this organism, with the species-level susceptibility crossing all breed lines. No breed has demonstrated resistance to yersiniosis.

Certain guinea pig populations face elevated risk due to management circumstances and stress factors rather than breed genetics. Guinea pigs in large colonies including breeding facilities, pet stores, rescue organizations, and shelters experience higher infection rates due to increased opportunities for pathogen introduction, stress from handling and environmental changes, and challenges of maintaining strict hygiene across large numbers of animals. Young guinea pigs under six months have immature immune systems placing them at higher risk for severe disease. Guinea pigs experiencing concurrent illness, nutritional deficiencies particularly vitamin C, or chronic stress have compromised immunity increasing susceptibility.

Screening and prevention recommendations apply equally across all guinea pig breeds with emphasis on environmental management rather than breed-specific protocols. Breeders and those maintaining multiple guinea pigs should implement strict protocols for food and bedding storage to prevent wild animal contamination. Quarantine of new animals before introduction protects established colonies. Regular health monitoring of all animals allows early detection of illness. Necropsy of guinea pigs that die helps identify infectious causes requiring colony-wide intervention. No breed is immune to yersiniosis, and prevention depends entirely on management practices rather than genetic selection.

Several conditions may co-occur with or result from yersiniosis in guinea pigs. Hepatic involvement is common as the infection spreads systemically, potentially causing liver dysfunction and contributing to overall clinical deterioration. Secondary bacterial infections may develop as the immune system is overwhelmed fighting Yersinia, potentially affecting respiratory or other organ systems. Gastrointestinal stasis, an emergency in guinea pigs, can develop secondary to anorexia and systemic illness from yersiniosis. Dehydration and electrolyte imbalances result from diarrhea and reduced intake, requiring aggressive fluid support. Malnutrition and muscle wasting develop during prolonged illness.

Several conditions present with symptoms similar to yersiniosis and must be differentiated through appropriate diagnostic testing. Salmonellosis causes similar gastrointestinal and systemic illness in guinea pigs, with differentiation requiring bacterial culture. Tyzzer's disease causes acute fatal enteritis with different organ involvement patterns. Other bacterial enteritides including those caused by Clostridium species and pathogenic Escherichia coli cause diarrhea and systemic illness. Antibiotic-associated dysbiosis from inappropriate antibiotic administration causes severe enterocolitis. Intestinal parasitism including coccidiosis causes diarrhea and wasting. Abdominal neoplasia including lymphoma may cause similar abdominal masses and systemic illness.

Potential complications of yersiniosis extend beyond the primary infection and affect long-term outcomes for survivors. Chronic carrier status represents a significant complication, with recovered guinea pigs potentially shedding bacteria intermittently and posing ongoing infection risks. Permanent organ damage from nodule formation in the liver, spleen, and other organs may affect long-term health and function. Relapse of clinical disease can occur during periods of stress or immune compromise. The zoonotic potential means human family members may be at risk from contact with infected or carrier guinea pigs. Spread to other guinea pigs in the household can cause colony-wide disease. These complications underscore the serious nature of this infection and the importance of considering all factors when making treatment decisions.