Myxomatosis (Myxoma virus)

Myxomatosis is a severe and often fatal viral disease of rabbits caused by the myxoma virus, a member of the Poxviridae family in the Leporipoxvirus genus. The disease primarily affects European rabbits (Oryctolagus cuniculus), which includes all domestic pet rabbit breeds, and causes devastating illness with mortality rates approaching ninety-five to ninety-nine percent in unvaccinated individuals. The virus originally evolved in South American tapeti rabbits and North American brush rabbits, which serve as natural reservoir hosts and experience only mild disease. When introduced to susceptible European rabbits, however, the virus causes severe systemic infection affecting multiple organ systems.

The myxoma virus was deliberately introduced as a biological control agent for wild rabbit populations in Australia in 1950 and in France in 1952, from where it spread throughout Europe. These introductions caused massive epidemics with nearly complete mortality in affected rabbit populations. Over subsequent decades, both viral attenuation and rabbit resistance have evolved, resulting in somewhat reduced mortality in wild populations, though myxomatosis remains a significant cause of rabbit mortality and continues to regulate wild rabbit numbers. Different strains of varying virulence exist worldwide, with the Californian strain found in North America being among the most virulent, approaching one hundred percent mortality.

The disease spreads primarily through biting insects including mosquitoes, fleas, mites, and ticks that carry viral particles from infected to susceptible rabbits. Direct contact with infected rabbits or contaminated materials also transmits infection. The virus can survive for extended periods on surfaces, in rabbit secretions, and in the environment. Clinical signs include characteristic swelling of the face, eyes, ears, and anogenital region, followed by fever, secondary infections, and progressive deterioration. The disease course typically spans one to two weeks in acute cases, with death resulting from systemic viral effects and secondary bacterial infections.

Prevention through vaccination represents the cornerstone of myxomatosis control in domestic rabbits in regions where the disease is endemic, including the United Kingdom, Europe, and Australia. Effective vaccines are available that significantly reduce disease severity, and vaccinated rabbits that become infected typically experience much milder illness with good survival rates. Unfortunately, no vaccine is currently approved for use in the United States, making prevention through insect control and avoiding wild rabbit exposure the primary protective strategies in affected American regions. There is no specific treatment for myxomatosis, and management relies entirely on supportive care. For unvaccinated rabbits that contract the disease, euthanasia is often the most humane option to prevent suffering.

The primary cause of myxomatosis is infection with the myxoma virus, a large double-stranded DNA virus in the family Poxviridae. The virus specifically targets European rabbits with high virulence, while causing minimal disease in its natural hosts, the South American tapeti (Sylvilagus brasiliensis) and North American brush rabbit (Sylvilagus bachmani). This host specificity reflects millions of years of co-evolution between the virus and its reservoir hosts, allowing a balance between viral persistence and host survival that does not exist with the more recently exposed European rabbit species. Multiple strains of myxoma virus exist with varying virulence, from highly lethal strains approaching complete mortality to attenuated strains causing milder disease.

Genetic and hereditary factors influence susceptibility and disease outcome at the population level but do not cause the disease itself. Following the introduction of myxomatosis to Australia and Europe, wild rabbit populations have developed increased genetic resistance over many generations. This resistance manifests as improved survival rates and milder disease courses in descendent populations compared to their ancestors or to naive populations. Individual variation in immune response affects disease outcome, with some rabbits mounting more effective responses than others. However, no domestic rabbit breed or individual is immune to myxomatosis in the absence of vaccination, and all unvaccinated European rabbits remain susceptible to severe disease.

Environmental and lifestyle factors significantly influence infection risk. The virus is transmitted primarily by biting insects, making insect exposure the dominant risk factor. Mosquitoes are particularly important vectors, capable of carrying the virus for extended periods and transmitting infection through blood-feeding. Fleas from wild rabbits, dogs, or cats commonly transmit the virus to domestic rabbits. Ticks and biting flies contribute to transmission in various geographic regions. Outdoor housing dramatically increases infection risk compared to indoor housing due to insect exposure. Geographic location determines disease presence, with myxomatosis endemic in Australia, Europe, and certain regions of the Americas but absent from other areas. Seasonal variation in insect activity affects infection rates, with peak transmission during warm months.

Risk factors for myxomatosis infection include any exposure to insect vectors in endemic regions. Outdoor rabbits face substantially higher risk than indoor-housed rabbits. Multi-pet households with dogs or cats that go outdoors may bring infected fleas into contact with rabbits. Proximity to wild rabbit populations increases risk, as wild rabbits serve as disease reservoirs. Unvaccinated status represents the primary risk factor for severe disease outcome, as vaccinated rabbits that become infected typically experience mild illness. Areas with standing water that supports mosquito breeding present elevated local risk. During outbreak periods in wild rabbit populations, transmission pressure to domestic rabbits increases substantially.

The mechanism of disease development involves viral entry through the skin, typically at the site of insect bite or through mucous membranes. The virus initially replicates at the inoculation site and in regional lymph nodes before spreading systemically via the bloodstream. Target organs include skin, eyes, respiratory tract, liver, and reproductive organs. The characteristic skin swellings result from proliferation of infected cells combined with inflammatory responses. Immunosuppression caused by the virus promotes secondary bacterial infections that contribute significantly to mortality. Virulent strains cause rapid systemic spread with severe multi-organ involvement and death within one to two weeks. Attenuated strains produce more prolonged, potentially survivable illness with nodular skin lesions rather than massive swelling.

Early warning signs of myxomatosis typically appear within one to three weeks following infection, depending on viral strain and individual susceptibility. The incubation period ranges from about five days to two weeks. Initial signs may include subtle lethargy, mild fever, and reduced appetite before more obvious symptoms develop. Owners may notice their rabbit seems quieter than normal or shows decreased interest in food or activities. Slight swelling or redness around the eyes, at the base of the ears, or in the genital area may be the first visible abnormalities. Because rabbits instinctively mask illness, early signs can be easily missed. Any rabbit in an endemic area showing vague illness during insect season should be considered at risk for myxomatosis.

Common symptoms of myxomatosis are distinctive and often allow clinical recognition. The hallmark sign is puffy, swollen skin particularly affecting the face, ears, eyelids, and anogenital region. Eyelid swelling may become so severe that eyes are completely closed, causing blindness. The characteristic appearance has been described as giving rabbits a sleepy look due to severely swollen eyelids. Swelling of the ears causes thickening and drooping. Genital swelling affects the vulva in females and the scrotum and prepuce in males. Nasal discharge and conjunctival discharge develop as the disease progresses. Skin lumps or nodules may appear across the body in some presentations. Fever develops, often reaching high levels.

Behavioral changes accompany the physical symptoms as affected rabbits become increasingly ill. Progressive lethargy develops as the disease advances, with rabbits becoming weak and reluctant to move. Appetite decreases dramatically, creating serious concern given rabbits' need for constant gut motility. Water intake often declines. Normal grooming behavior ceases as the rabbit becomes too ill to maintain self-care. Social withdrawal from companions and human interaction reflects the rabbit's deteriorating condition. Affected rabbits may sit hunched in one position. Breathing may become labored as respiratory involvement develops. The combination of facial swelling and respiratory disease can make breathing and eating extremely difficult.

Physical signs beyond the characteristic swelling include various manifestations of multi-organ involvement. Skin lesions range from massive gelatinous swelling in acute cases to multiple nodular lumps in more chronic presentations. Secondary bacterial skin infections produce discharge, crusting, and odor. Conjunctivitis with purulent discharge affects the eyes. Respiratory signs include nasal discharge that may become thick and purulent, increased breathing rate, and labored respiration. Body temperature typically elevates initially, then may drop as the rabbit deteriorates. Weight loss develops rapidly due to inability to eat. Mucous membrane color may change with fever or circulatory compromise.

Symptom progression in myxomatosis follows a relatively predictable course, though timing varies with viral strain virulence. Following initial swelling around the face and anogenital area, fever develops and the rabbit's condition worsens over several days. Swelling typically progresses to peak severity over approximately one week. Secondary bacterial infections develop, causing pneumonia, abscesses, and septicemia that contribute to mortality. In acute cases with virulent strains, death typically occurs within ten to fourteen days of symptom onset, often from respiratory failure, secondary infections, or systemic collapse. More attenuated strains may produce prolonged illness over three to five weeks with potential for survival in some cases, though scarring and disfigurement often result.

Emergency symptoms requiring immediate veterinary attention include any signs suggestive of myxomatosis in an endemic region. A rabbit with facial swelling, eye swelling, or genital swelling should be isolated from other rabbits and seen by a veterinarian immediately. Severe respiratory distress, complete inability to eat or drink, or complete closure of the eyes from swelling warrant urgent care. Any rabbit that has not eaten for twelve hours or more is at risk for GI stasis, which can become fatal within twenty-four to forty-eight hours. Absence of fecal production for twelve hours constitutes an emergency. Open-mouth breathing is always a dire emergency in rabbits. Collapse, severe weakness, or unresponsiveness indicate critical illness requiring immediate veterinary assessment.

Initial examination for suspected myxomatosis begins with comprehensive assessment by a veterinarian, ideally one experienced with rabbit diseases. The characteristic clinical presentation of facial and anogenital swelling combined with appropriate exposure history often strongly suggests the diagnosis. The veterinarian will obtain detailed history including vaccination status, housing situation, outdoor exposure, potential contact with wild rabbits or insect vectors, and geographic location relative to endemic areas. Physical examination documents the extent and distribution of swelling, presence of skin nodules, respiratory status, ocular involvement, and overall condition. The unique appearance of myxomatosis often permits tentative diagnosis based on clinical signs alone.

Diagnostic testing can confirm myxomatosis when clinical diagnosis is uncertain or when confirmation is needed for disease surveillance purposes. PCR testing detects viral DNA in skin lesions or tissue samples with high sensitivity and specificity, providing definitive molecular confirmation. Virus isolation from lesion material grown in cell culture provides another confirmatory method, though it is more time-consuming. Histopathological examination of skin biopsies reveals characteristic myxoma cells with distinctive cytoplasmic inclusions. Electron microscopy can visualize characteristic poxvirus particles. Serological testing detects antibodies to myxoma virus, which is more useful for population surveillance than individual diagnosis in acute cases. In clinical practice, the distinctive presentation often makes extensive testing unnecessary for case management.

Differential diagnosis for myxomatosis includes other conditions that may cause facial swelling or skin nodules in rabbits. Bacterial abscesses from Pasteurella or other organisms can cause localized facial swelling but typically lack the bilateral symmetry and multi-site involvement of myxomatosis. Allergic reactions may cause facial swelling but usually develop more rapidly and respond to antihistamines. Dental disease with associated facial abscesses produces swelling but is generally unilateral and associated with dental abnormalities on examination. Rabbit hemorrhagic disease virus causes acute illness and death but without the characteristic swelling of myxomatosis. Shope fibroma virus causes skin tumors that differ in appearance from myxomatosis lesions. In endemic areas during peak transmission season, myxomatosis should be strongly suspected in any rabbit presenting with compatible signs.

Diagnosis confirmation matters for disease reporting, public health surveillance, and informing other rabbit owners in the area about outbreak activity. Myxomatosis is a reportable disease in many jurisdictions, and confirmed cases should be reported to appropriate veterinary authorities. In the United States, particularly California and other western states where outbreaks occur, reporting helps track disease activity and alerts the rabbit community. In the United Kingdom and Europe, confirmed cases inform vaccine efficacy monitoring and outbreak response. For individual case management, clinical diagnosis is usually sufficient to guide treatment decisions, as the prognosis and supportive care approach remain the same regardless of laboratory confirmation.

Emergency and immediate treatment for myxomatosis focuses on supportive care, as no specific antiviral treatment exists. Affected rabbits should be immediately isolated from other rabbits to prevent disease spread. Initial assessment determines whether treatment is appropriate or whether euthanasia represents the most humane option, a decision that depends largely on vaccination status and severity of presentation. For vaccinated rabbits with mild disease, intensive supportive care offers reasonable hope of recovery. For unvaccinated rabbits with severe myxomatosis, the disease is nearly always fatal, and euthanasia to prevent prolonged suffering is typically recommended. Hospitalization may be appropriate for cases where treatment is attempted.

Medical management of myxomatosis consists entirely of supportive measures addressing symptoms and complications. Fluid therapy combats dehydration from fever and reduced drinking, administered subcutaneously or intravenously depending on severity. Non-steroidal anti-inflammatory medications such as meloxicam help reduce fever, inflammation, and discomfort. Antibiotics are essential to address secondary bacterial infections including pneumonia, skin infections, and septicemia, using rabbit-safe agents such as enrofloxacin or trimethoprim-sulfa. Pain management promotes comfort and supports appetite. Topical treatments for eyes may help with conjunctival involvement. There is no medication that targets the myxoma virus itself, and treatment cannot eliminate the viral infection but rather supports the rabbit while the immune system attempts to control it.

Surgical options do not apply directly to myxomatosis treatment, as the disease involves systemic viral infection rather than surgically correctable pathology. However, veterinary procedures may be needed for supportive care delivery, such as placement of feeding tubes in rabbits unable to eat due to facial swelling. Any anesthesia in severely ill rabbits carries substantial risk and should be carefully considered. The fundamental principle that rabbits must never be fasted before anesthesia remains important even in sick animals.

Supportive care represents the cornerstone of myxomatosis management in cases where treatment is attempted. Nutritional support is absolutely critical, as affected rabbits often cannot eat due to facial swelling, weakness, or respiratory compromise. Syringe feeding with critical care formula maintains gut function and prevents hepatic lipidosis. Encouraging fluid intake through syringe-fed water, wetting vegetables, or flavored water supports hydration alongside veterinary fluid administration. Keeping the rabbit warm and comfortable promotes recovery. Cleaning discharge from eyes, nose, and other affected areas maintains comfort and prevents secondary complications. Gentle nursing care in a quiet, stress-free environment supports the rabbit's ability to mount an immune response.

Alternative and complementary approaches to myxomatosis are limited given the severity of the disease. Stress reduction through quiet housing, minimal handling except for essential care, and familiar surroundings supports immune function. Probiotics may help maintain gut health during illness and antibiotic treatment. Environmental modifications ensuring easy access to food and water accommodate visual impairment from eye swelling. There are no proven herbal or alternative treatments that affect myxomatosis outcome, and emphasis must remain on veterinary supportive care.

Treatment decisions for myxomatosis require honest assessment of prognosis and quality of life considerations. For unvaccinated rabbits with severe disease, recovery is extremely rare, and prolonged treatment often extends suffering without realistic hope of survival. Euthanasia is frequently the most humane choice in these cases. For vaccinated rabbits that develop breakthrough infections, disease is typically milder, and intensive supportive care often results in recovery. Decision factors include vaccination status, severity of presentation, availability of intensive nursing care, and owner commitment to potentially prolonged treatment. Veterinary guidance helps owners make appropriate decisions balancing hope for recovery against prevention of unnecessary suffering.

Recovery timeline for myxomatosis varies dramatically based on vaccination status and disease severity. Vaccinated rabbits with mild breakthrough infections may improve within one to two weeks with supportive care, achieving substantial recovery over three to five weeks. Unvaccinated rabbits that survive, which is rare with virulent strains, experience prolonged illness often extending six weeks or longer. Recovery is gradual, with slow resolution of swelling, improvement in appetite and activity, and healing of secondary infections. Some rabbits retain permanent scarring or disfigurement from severe tissue damage, particularly around the face and ears. Complete recovery to normal appearance and function is possible but not universal.

Post-treatment care for surviving rabbits focuses on continued supportive measures and monitoring for complications. Nutritional support continues until the rabbit eats adequately on its own, with syringe feeding maintained as needed. Medication courses including antibiotics should be completed as prescribed even as the rabbit improves. Wound care for any skin lesions promotes healing and prevents secondary infection. Activity may be restricted initially while the rabbit regains strength. Follow-up veterinary examinations assess recovery progress and identify any emerging problems. Surviving rabbits should be monitored for several weeks after apparent recovery to ensure no delayed complications develop.

Prognosis factors for myxomatosis center primarily on vaccination status. Vaccinated rabbits have dramatically better prognosis than unvaccinated rabbits, with most vaccinated individuals surviving even if they contract the disease. Disease severity at presentation affects outcome, with milder cases having better prognosis than severe systemic illness. Viral strain virulence matters significantly, as highly virulent strains like those found in California cause nearly universal mortality while attenuated European strains may be more survivable. Early intervention with supportive care improves chances compared to delayed treatment. Overall health status and immune function influence the rabbit's ability to combat infection.

Long-term outlook following myxomatosis recovery is generally favorable for survivors, though some considerations apply. Rabbits that recover develop immunity to myxomatosis that provides protection against reinfection. The duration and completeness of immunity may vary, and continued vaccination is recommended to maintain protection. Some survivors retain permanent changes including scarring, partial blindness from eye damage, or tissue loss affecting ears or other structures. These changes may require ongoing accommodation but often do not prevent good quality of life. Survivors remain capable of normal activities and can enjoy good health following recovery. Mental health and behavior typically return to normal as physical recovery progresses.

Primary prevention of myxomatosis in endemic regions relies fundamentally on vaccination. Effective vaccines are available in the United Kingdom, Europe, and Australia that provide substantial protection against myxomatosis. Vaccinated rabbits may still contract the disease but typically experience much milder illness with excellent survival rates. Vaccination protocols recommend initial vaccination as early as five weeks of age, with annual boosters to maintain protection. Combined vaccines protecting against both myxomatosis and rabbit hemorrhagic disease are available and provide convenient comprehensive protection. Unfortunately, no vaccine against myxomatosis is currently approved for use in the United States, making other preventive strategies particularly important in American endemic areas.

Environmental prevention measures focus on reducing insect vector exposure. Indoor housing provides the most effective protection, eliminating contact with mosquitoes, fleas, and other biting insects that transmit the virus. For rabbits housed outdoors, mosquito netting or fine mesh screening over enclosures prevents flying insect access. Eliminating standing water from gardens and yards reduces mosquito breeding. Using appropriate rabbit-safe flea prevention products reduces flea-mediated transmission. Treating dogs and cats in the household for fleas prevents them from carrying infected fleas to rabbits. Avoiding areas with high wild rabbit activity reduces environmental exposure risk. Purchasing hay and straw from sources where myxomatosis has not been observed may reduce contamination risk.

Dietary prevention does not directly apply to myxomatosis, as infection results from viral exposure rather than nutritional factors. However, maintaining optimal nutrition supports immune function, which influences disease severity if exposure occurs. Unlimited grass hay comprising at least eighty percent of the diet maintains digestive and overall health. Appropriate quality pellets provide balanced nutrition. Fresh leafy greens daily offer variety and additional nutrients. Avoiding high-sugar and high-starch treats supports metabolic health. Fresh, clean water must always be available. Good overall nutrition helps ensure the rabbit's immune system is optimally prepared to respond to any disease challenge.

Health maintenance practices support prevention and early detection. Regular veterinary examinations with a rabbit-savvy veterinarian maintain overall health and provide vaccination opportunities in endemic regions. Maintaining up-to-date vaccination is the single most important preventive measure where vaccines are available. Regular parasite prevention reduces flea and other vector populations. Clean, dry housing with regular disinfection using rabbit-safe products maintains environmental hygiene. Quarantining new rabbits before introducing them to existing rabbits prevents disease introduction. Minimizing stress supports immune function.

Early intervention in myxomatosis primarily means seeking veterinary care immediately when any suspicious signs develop. In endemic areas, owners should be familiar with early myxomatosis signs and contact their veterinarian promptly if concerns arise. Early supportive care initiation may improve outcomes in vaccinated rabbits with mild disease. Isolation of suspected cases prevents transmission to other rabbits. Reporting confirmed or suspected cases to veterinary authorities supports disease surveillance and community awareness. Building a relationship with a rabbit-savvy veterinarian before problems develop ensures rapid access to appropriate care when needed.

Daily management of rabbits recovering from myxomatosis requires intensive nursing care during the acute phase and continued monitoring during convalescence. During illness, affected rabbits need frequent assessment of hydration, appetite, breathing, and comfort. Syringe feeding may be required multiple times daily for rabbits unable to eat independently. Medication administration must follow prescribed schedules. Gentle cleaning of discharge from eyes, nose, and skin promotes comfort. Environmental temperature should be maintained at comfortable levels. As recovery progresses, the frequency of intensive interventions gradually decreases. Throughout recovery, monitoring food intake, water consumption, and fecal output remains essential to ensure continued improvement.

Home environment modifications support rabbits during illness and recovery. Isolation from other rabbits prevents disease transmission and provides quiet recovery space. Soft, clean bedding that is changed frequently maintains hygiene and comfort. Easy access to food, water, and litter box accommodates weakness and visual impairment from eye swelling. Low-sided litter boxes help debilitated rabbits. Floor-level housing eliminates fall risks for weak or visually impaired rabbits. Appropriate temperature control prevents chilling in sick rabbits. Dim lighting may be more comfortable for rabbits with eye involvement. After recovery, environment should be thoroughly cleaned and disinfected before reintroducing recovered rabbits or housing new rabbits.

Quality of life considerations are paramount in myxomatosis management given the disease severity and often poor prognosis. For unvaccinated rabbits with severe disease, prolonged treatment that extends suffering without realistic hope of recovery is not in the rabbit's best interest. Signs of good quality of life during recovery include gradual improvement in alertness, some interest in food, response to gentle interaction, and absence of apparent severe distress. Signs of poor quality of life warranting reassessment of treatment approach include persistent severe distress, complete inability to eat despite syringe feeding, severe respiratory difficulty, or progressive deterioration despite supportive care. Honest discussion with the veterinarian about quality of life helps guide appropriate decisions.

Monitoring and ongoing care for myxomatosis survivors continues beyond the acute illness. Watching for any delayed complications or recurrence of symptoms identifies problems early. Regular veterinary checkups assess recovery progress and long-term health. For rabbits with permanent damage such as visual impairment or disfigurement, environmental accommodations support continued quality of life. Maintaining vaccination if available prevents future infection. Weight monitoring and general health assessment identify any emerging issues. Survivors typically return to normal behavior and activity as they heal.

Caregiver support resources help owners navigate the challenging experience of managing a rabbit with myxomatosis. The House Rabbit Society and similar organizations provide information about the disease and emotional support for affected owners. Online communities connect rabbit owners facing similar situations. In regions with active outbreaks, community awareness and information sharing help protect other rabbits. Financial considerations for treatment, if attempted, may be substantial. Emotional support is particularly important given the often-poor prognosis and the difficult decisions owners may face. Veterinary team communication helps owners understand options, make informed decisions, and cope with outcomes regardless of whether the rabbit survives.

Myxomatosis does not demonstrate breed-specific risk within domestic rabbits, as all breeds of European rabbit (Oryctolagus cuniculus) are susceptible to infection and severe disease. The relevant distinction is species rather than breed, with European rabbits being highly susceptible while South American tapeti rabbits and North American brush rabbits serve as natural reservoir hosts that experience only mild disease. All domestic pet rabbit breeds, from dwarf varieties to giant breeds, face equal risk of infection and similar disease outcomes when exposed to the virus. No selective breeding has produced myxomatosis-resistant domestic rabbit breeds. The host species susceptibility means that breed choice cannot serve as a preventive strategy.

Risk categories for myxomatosis relate primarily to geographic location, vaccination status, and environmental exposure rather than breed characteristics. Geographic distribution is the primary determinant of risk, as the disease is endemic in Australia, Europe, and certain regions of the Americas but absent from other areas. Within endemic regions, outdoor rabbits face substantially higher risk than indoor rabbits due to insect vector exposure. Unvaccinated rabbits in endemic areas are at highest risk of severe disease and death. Proximity to wild rabbit populations increases exposure risk. Seasonal factors with peak risk during warm months when insect vectors are active influence infection timing.

Screening recommendations for myxomatosis focus on vaccination rather than diagnostic screening in healthy rabbits. In endemic regions with available vaccines, all rabbits should receive myxomatosis vaccination according to recommended protocols, typically beginning at five to ten weeks of age with annual boosters. Vaccination status should be documented and maintained current. In non-endemic areas or where vaccines are unavailable, prevention emphasizes environmental measures. All rabbit owners in or near endemic areas should be familiar with myxomatosis signs and seek immediate veterinary attention if suspicious symptoms develop. During outbreak periods, heightened awareness and precautions protect domestic rabbit populations regardless of breed.

Commonly co-occurring conditions with myxomatosis primarily include secondary bacterial infections that develop as the virus suppresses immune function. Pneumonia caused by Pasteurella, Bordetella, or other respiratory pathogens frequently complicates myxomatosis and contributes significantly to mortality. Skin infections from various bacteria affect damaged tissues. Conjunctivitis with secondary bacterial involvement affects eyes. Gastrointestinal stasis commonly develops secondary to reduced appetite, fever, and general illness, representing a significant complication requiring management. Hepatic lipidosis may result from prolonged anorexia. These secondary conditions often determine survival as much as the primary viral infection.

Conditions with similar symptoms to myxomatosis require consideration in differential diagnosis. Rabbit hemorrhagic disease causes acute death but without the characteristic swelling of myxomatosis. Pasteurella infections can cause facial swelling and respiratory signs but typically without the distinctive bilateral periocular and anogenital involvement. Allergic reactions may produce facial swelling but usually respond to treatment and lack systemic illness. Dental disease with abscesses causes facial swelling but is typically unilateral. Heat stroke can cause lethargy and distress. Encephalitozoon cuniculi may cause neurological signs that could initially be confused with weakness from myxomatosis. In endemic regions during transmission season, myxomatosis should be suspected in any rabbit with compatible signs.

Potential complications of myxomatosis extend beyond the direct viral effects. Secondary bacterial pneumonia represents the most common serious complication and frequent cause of death. Bacterial septicemia from secondary infections causes systemic illness. Severe eye damage from conjunctivitis and swelling may result in permanent visual impairment or blindness. Skin necrosis and scarring leave permanent disfigurement. GI stasis from reduced eating can become life-threatening independently of the viral infection. Hepatic lipidosis develops from prolonged anorexia. Prevention of complications focuses on early supportive care including antibiotics for secondary infections, nutritional support to prevent GI stasis, and nursing care to maintain comfort and prevent additional complications.