Myxomatosis (ocular)

Myxomatosis is a severe and often fatal viral disease affecting rabbits, caused by the Myxoma virus, a member of the Poxviridae family. While myxomatosis affects multiple body systems, the ocular manifestations are among the most characteristic and distressing features of the disease. Ocular myxomatosis presents with dramatic swelling of the eyelids and conjunctiva, often so severe that the eyes become completely closed and encrusted with discharge. This ocular involvement is frequently the first obvious sign of infection that rabbit owners notice and represents a hallmark of the disease that allows for clinical recognition. The condition is most common in wild rabbit populations but poses a serious threat to domestic rabbits, particularly those with outdoor access or in areas where the virus is endemic.

The Myxoma virus is transmitted primarily through biting insects, including mosquitoes, fleas, and fur mites, which serve as mechanical vectors carrying the virus from infected to susceptible rabbits. Direct contact with infected rabbits or contaminated materials can also spread the disease. The virus originated in South American wild rabbits, where it causes only mild disease in the native species, but European rabbits, from which all domestic breeds are derived, are highly susceptible and develop severe, usually fatal illness. The virus was deliberately introduced to Australia and Europe as a biological control measure for wild rabbit populations, and it has since become established in these regions, creating ongoing risk for domestic rabbits.

The impact of myxomatosis on affected rabbits is devastating, with mortality rates often exceeding ninety percent in unvaccinated rabbits exposed to virulent strains. Ocular involvement causes significant suffering as severe eyelid swelling prevents normal vision, eating, and drinking. The conjunctival inflammation and discharge cause pain and discomfort. Secondary bacterial infections commonly develop due to compromised tissue integrity and immune suppression. Beyond the eyes, the virus affects the respiratory system, skin, and internal organs, leading to systemic illness. Affected rabbits typically deteriorate rapidly, and even with intensive supportive care, survival is unlikely for those infected with classic virulent strains.

There is no specific antiviral treatment for myxomatosis, and care is limited to supportive measures while the rabbit's immune system attempts to fight the infection. The prognosis is grave for rabbits infected with virulent strains, and euthanasia is often the most humane option to prevent prolonged suffering. However, vaccination provides effective protection in areas where the disease is endemic, and this represents the primary approach to controlling myxomatosis in domestic rabbits. Rabbit owners in endemic areas should consult with a rabbit-savvy veterinarian about vaccination protocols and take measures to reduce exposure to insect vectors that can transmit the virus.

The primary cause of myxomatosis is infection with the Myxoma virus, a large DNA virus belonging to the Leporipoxvirus genus within the Poxviridae family. This virus has a specific affinity for rabbit tissue and causes severe disease in European rabbits and their domestic descendants while causing only mild symptoms in its natural host, the South American brush rabbit. The virus particles are highly stable in the environment and can survive for extended periods on surfaces, in rabbit burrows, and on insect vectors. Multiple strains of Myxoma virus exist, varying in virulence from highly lethal strains that cause acute, rapidly fatal disease to attenuated strains that cause milder illness with higher survival rates. The strain circulating in a particular geographic area significantly influences the clinical presentation and outcomes in affected rabbits.

Transmission of the Myxoma virus occurs primarily through arthropod vectors, particularly biting insects that carry virus particles on their mouthparts from infected to susceptible rabbits. Mosquitoes are the most important vectors in many regions, with the virus remaining viable on mosquito mouthparts for extended periods. Rabbit fleas, particularly the European rabbit flea Spilopsyllus cuniculi, are highly efficient vectors and can maintain the virus through their life cycle. Fur mites, biting flies, and other blood-feeding insects can also transmit the virus. Direct transmission between rabbits occurs through contact with ocular, nasal, or genital secretions from infected animals, though this route is generally less efficient than vector transmission. Fomite transmission through contaminated equipment, bedding, or human hands is possible given the virus's environmental stability.

Environmental and lifestyle factors significantly influence a rabbit's risk of exposure to myxomatosis. Outdoor housing dramatically increases risk due to greater exposure to insect vectors, particularly mosquitoes during warmer months. Geographic location matters considerably, with rabbits living in regions where myxomatosis is endemic facing ongoing exposure risk. Proximity to wild rabbit populations increases risk, as wild rabbits serve as a reservoir for the virus. Seasonal factors affect transmission, with peak risk during periods of high insect activity, typically late summer and fall in temperate climates. Urban rabbits may have lower exposure risk than those in rural areas with larger wild rabbit populations, though mosquitoes can carry the virus into any environment.

Risk factors for developing myxomatosis after exposure include vaccination status, immune function, and the virulence of the infecting strain. Unvaccinated rabbits are highly susceptible and have little natural resistance to the virus. Young rabbits, elderly rabbits, and those with compromised immune systems from other illness or chronic stress may be more susceptible to severe disease. Rabbits previously exposed to attenuated strains may have some immunity that provides partial protection against subsequent exposure. The specific strain of virus encountered dramatically affects outcomes, with classic virulent strains causing near-universal mortality in naive populations while attenuated strains may allow higher survival rates.

The mechanism of disease development following Myxoma virus infection involves initial replication at the site of inoculation, typically where an insect bite introduced the virus, followed by spread through the lymphatic system and bloodstream to multiple organs. The virus has particular tropism for lymphoid tissue, skin, and mucosal surfaces, explaining the characteristic skin nodules and severe ocular and respiratory involvement. The ocular manifestations result from viral replication in conjunctival tissue causing severe inflammation, edema, and discharge. The virus causes immunosuppression, which allows secondary bacterial infections to develop and worsen the clinical picture. In acute infections with virulent strains, death typically results from respiratory failure, secondary bacterial infection, or systemic inflammatory response within one to two weeks of symptom onset.

Early warning signs of myxomatosis may be subtle initially but progress rapidly once the disease becomes established. The incubation period following exposure typically ranges from five to fourteen days, during which the rabbit may appear completely normal. Initial signs often include mild conjunctival redness and a slight watery discharge from one or both eyes that could easily be mistaken for a minor eye irritation. A small swelling or nodule may develop at the site of the insect bite that introduced the virus, though this is often overlooked. Affected rabbits may show subtle behavioral changes including slightly reduced activity or appetite. Fever develops during the incubation period before obvious symptoms appear. Because rabbits instinctively hide illness, these early signs may not be recognized until more dramatic symptoms develop.

The characteristic ocular symptoms of myxomatosis become dramatically apparent as the disease progresses and represent the most recognizable feature of the condition. Severe swelling of the eyelids develops, often so pronounced that the eyes swell completely shut. The conjunctiva becomes extremely inflamed and edematous, bulging out from between the swollen eyelids. A thick, purulent discharge accumulates, matting the fur around the eyes and crusting over the closed eyelids. Both eyes are typically affected, though the severity may differ between eyes. The swelling extends to surrounding facial tissue, giving the rabbit a grotesquely distorted appearance. This characteristic facial swelling, combined with the closed, discharging eyes, creates the pathognomonic presentation that allows clinical recognition of myxomatosis.

Behavioral changes in rabbits with myxomatosis reflect the severe systemic illness and blindness caused by the swollen eyes. Affected rabbits become markedly lethargic and spend most of their time in a hunched position. Appetite typically decreases dramatically or ceases entirely, creating risk of secondary gastrointestinal stasis. The inability to see due to swollen eyelids causes disorientation and reluctance to move. Rabbits may stop grooming and cease normal activities. Eating and drinking become physically difficult due to facial swelling affecting the mouth and nose as well as the eyes. The rabbit may appear depressed and unresponsive to stimulation that would normally elicit a reaction.

Physical signs beyond the ocular involvement include the development of myxomatous nodules or swellings on other parts of the body. The nose and lips typically swell significantly, contributing to the characteristic facial distortion. The genital region often becomes swollen and edematous, sometimes severely. Nodules may develop on the ears, which also frequently swell and droop. The skin around affected areas may become thickened and develop a gelatinous texture. Respiratory symptoms often develop, including nasal discharge, sneezing, and labored breathing as the virus affects the respiratory tract and secondary bacterial pneumonia develops. Generalized weakness and poor body condition reflect the systemic nature of the disease.

Symptom progression in classic virulent myxomatosis follows a predictable and devastating course. After initial mild signs, the dramatic facial swelling typically develops over two to three days and becomes maximal within a week of visible illness. As the disease progresses, secondary bacterial infections commonly develop in the compromised tissues, worsening discharge and causing systemic illness. Respiratory involvement may cause progressive difficulty breathing. The rabbit becomes increasingly weak, dehydrated from inability to eat and drink adequately, and systemically ill. Body temperature may fluctuate. Most rabbits infected with virulent strains die within ten to fourteen days of symptom onset, though some survive longer with supportive care.

Emergency symptoms requiring immediate veterinary attention include any signs consistent with myxomatosis in areas where the disease is endemic, as early intervention offers the only chance of survival for any affected rabbit. Complete inability to open the eyes, severe facial swelling, refusal to eat or drink, labored breathing, and extreme lethargy all indicate serious illness requiring urgent evaluation. Not eating for twelve hours or more is always an emergency in rabbits and can trigger fatal gastrointestinal stasis. Open-mouth breathing indicates respiratory compromise and represents a dire emergency. Any rabbit suspected of having myxomatosis should be isolated immediately from other rabbits to prevent disease spread while veterinary attention is sought.

Initial veterinary examination for suspected myxomatosis focuses on the characteristic clinical presentation that strongly suggests this diagnosis. The combination of severe bilateral eyelid swelling with purulent discharge, facial edema affecting the nose and lips, genital swelling, and skin nodules creates a clinical picture that is highly suggestive of myxomatosis in endemic areas. The veterinarian will assess the extent of ocular involvement, respiratory status, overall body condition, and hydration status. A detailed history regarding vaccination status, potential exposure to wild rabbits or insect vectors, and housing conditions helps assess risk factors. The rabbit's geographic location is important, as myxomatosis risk varies considerably between regions.

Laboratory confirmation of myxomatosis involves detecting the virus or evidence of infection through various testing methods. Virus isolation from affected tissue samples, typically swabs of ocular discharge or biopsy of skin nodules, can be performed at specialized diagnostic laboratories. Polymerase chain reaction testing provides rapid and sensitive detection of viral DNA and is increasingly the method of choice for confirming diagnosis. Electron microscopy can identify poxvirus particles in tissue samples. Histopathology of affected tissue reveals characteristic changes including myxomatous degeneration with accumulation of mucinous material and typical viral inclusion bodies. Serological testing can detect antibodies to the virus but may not distinguish between current infection and previous exposure or vaccination.

Blood work and additional testing help assess the rabbit's overall condition and guide supportive care decisions. Complete blood count may reveal changes consistent with viral infection and secondary bacterial complications. Serum biochemistry provides information about organ function and hydration status. Thoracic radiographs may be indicated if respiratory involvement is suspected, looking for evidence of pneumonia or other complications. These tests help determine the severity of illness and whether the rabbit is a candidate for supportive treatment or whether euthanasia should be considered.

Differential diagnosis for the ocular presentation of myxomatosis includes other conditions that cause severe conjunctival swelling and discharge, though the dramatic presentation of myxomatosis is usually distinctive. Severe bacterial conjunctivitis from Pasteurella or other organisms can cause significant eye inflammation but typically lacks the extreme eyelid swelling and systemic signs of myxomatosis. Treponematosis, or rabbit syphilis, can cause facial lesions but has a different appearance and distribution. Allergic reactions might cause facial swelling but would not follow the progressive course or include systemic signs. Trauma or insect stings could cause localized swelling but would typically be unilateral and not progressive. Abscesses from various causes might produce facial swelling but again would have different characteristics. In endemic areas, the classic presentation of myxomatosis is usually recognizable clinically even before laboratory confirmation.

Emergency management of rabbits with myxomatosis focuses on immediate supportive care while the diagnosis is confirmed and prognosis assessed. Affected rabbits should be isolated immediately from all other rabbits to prevent disease transmission. The eyes should be gently cleaned using warm saline or sterile water to remove accumulated discharge and crusting, which can help maintain some comfort though it will not affect the disease course. Pain management with rabbit-safe medications such as meloxicam addresses the significant discomfort associated with the tissue swelling and inflammation. Fluid therapy, either subcutaneous or intravenous depending on the rabbit's condition, combats dehydration. If the rabbit is not eating, syringe feeding with critical care formula must begin immediately to prevent gastrointestinal stasis.

Medical treatment for myxomatosis is strictly supportive, as no antiviral medications are effective against the Myxoma virus. Antibiotics are commonly administered to treat or prevent secondary bacterial infections, which frequently complicate the compromised tissue integrity and immunosuppression caused by the virus. Appropriate antibiotics include enrofloxacin and other fluoroquinolones, trimethoprim-sulfa combinations, and chloramphenicol, while oral penicillin-based antibiotics must be avoided due to their toxicity to the rabbit intestinal flora. Topical antibiotic ophthalmic preparations may help manage secondary bacterial infection of the eyes. Anti-inflammatory medications help reduce swelling and provide comfort. Intensive nursing care including frequent eye cleaning, assisted feeding, and fluid support is essential for any rabbit being treated.

The prognosis for rabbits with myxomatosis is extremely guarded to grave, particularly for those infected with virulent strains of the virus. Mortality rates with classic virulent strains typically exceed ninety percent even with intensive supportive care. Some rabbits infected with attenuated strains that have evolved in endemic areas may have better survival chances, particularly with aggressive supportive care. Young adult rabbits with good body condition and strong immune systems have slightly better prospects than very young, old, or debilitated individuals. Any recovery typically requires two to three weeks or longer of intensive nursing care, and survivors may have permanent scarring or other sequelae.

Supportive care protocols for rabbits being treated for myxomatosis require intensive nursing and monitoring. Eye care involves gentle cleaning multiple times daily to remove discharge and prevent complete crusting over of the eyelids. Artificial tears or eye lubricants help maintain comfort and corneal health. Assisted feeding with syringe feeding of critical care formula is essential, as affected rabbits are often unable to eat independently due to facial swelling and general malaise. Subcutaneous fluids may need to be administered multiple times daily to maintain hydration. The rabbit should be kept warm, clean, and in a quiet environment. Monitoring includes assessing breathing effort, food intake, fecal output, and overall condition at least twice daily.

Euthanasia considerations are an important and often necessary part of myxomatosis case management. Given the extremely poor prognosis for rabbits with virulent strains, the significant suffering involved, and the lack of effective treatment, euthanasia is often the most humane option. This is particularly true for rabbits showing severe systemic signs, respiratory distress, or complete inability to eat and drink. The decision must balance the small chance of recovery against the certain suffering that continued treatment involves. In some jurisdictions, myxomatosis may be a reportable disease with regulations requiring notification of veterinary authorities, and these requirements should be followed.

Treatment decisions for myxomatosis must weigh multiple factors including the likelihood of recovery, the welfare of the affected rabbit, and the risk of disease spread to other rabbits. Some owners may wish to attempt treatment despite the poor prognosis, which requires understanding the intensive care involved and realistic expectations about outcomes. Others may choose euthanasia as the kindest option given the severity of the disease. The risk of virus transmission to other rabbits in the household or area must be considered and appropriate biosecurity measures implemented regardless of treatment choice. Any surviving rabbits should be monitored for delayed complications and may have permanent effects from their illness.

Recovery timeline for the rare rabbits that survive myxomatosis is prolonged and uncertain. The acute phase of illness typically lasts one to two weeks, during which the rabbit is critically ill and requires intensive supportive care. If the rabbit begins to improve, signs include gradual reduction in facial swelling, return of some appetite, and stabilization of overall condition. Full resolution of the dramatic swelling may take three to four weeks or longer, and significant facial scarring often remains. The recovery period requires continued intensive nursing care even as improvement becomes apparent. Complete recovery, if achieved, typically takes six to eight weeks from the onset of illness, though some effects may be permanent.

Post-recovery care for myxomatosis survivors addresses both immediate nursing needs and long-term monitoring. As swelling resolves and the rabbit begins eating independently, syringe feeding can be gradually reduced while ensuring adequate nutritional intake. Eye care may need to continue long-term if corneal damage or chronic discharge persists. The rabbit should remain isolated from other rabbits during recovery and for some period afterward, as virus shedding may continue even as clinical signs resolve. Follow-up veterinary examinations assess healing progress and monitor for complications. Weight monitoring ensures adequate nutrition during recovery.

Prognosis for rabbits that survive myxomatosis is guarded due to the potential for lasting effects and complications. Survivors often have permanent scarring of the eyelids and facial skin from the extensive tissue damage. Corneal scarring or other permanent eye damage may result in vision impairment. Respiratory scarring from pneumonia may cause chronic issues. The immunosuppression caused by the virus may have lasting effects on the rabbit's ability to fight other infections. However, rabbits that do survive typically develop immunity that provides protection against future infection, and some survivors go on to live reasonably normal lives despite their scars.

Long-term outlook for myxomatosis survivors requires ongoing attention to their health and welfare. Regular veterinary monitoring helps detect any delayed complications or chronic issues resulting from the illness. The rabbit's immune status may be compromised for some time following recovery, requiring attention to preventing other infections. Vaccination status should be discussed with the veterinarian, as different vaccines may or may not be indicated for survivors. Environmental management continues to be important to reduce future exposure risk. Survivors may have permanent physical changes including scarring, thickened skin, or visual impairment that require accommodation in their care.

Vaccination represents the primary and most effective prevention measure for myxomatosis in areas where the disease is endemic. Several vaccines are available in countries where myxomatosis is prevalent, including both modified live vaccines and newer recombinant vaccines. The recombinant vaccine commonly used in Europe and other regions provides protection against both myxomatosis and rabbit hemorrhagic disease with a single injection. Vaccination should begin in young rabbits and requires booster doses, typically annually, to maintain protection. Vaccine availability varies by country, and owners should consult with a rabbit-savvy veterinarian about appropriate vaccination protocols for their geographic area. While vaccination greatly reduces the risk of disease, it may not provide complete protection against all strains.

Vector control is an essential component of myxomatosis prevention, as the virus is primarily transmitted by biting insects. Mosquito control measures including eliminating standing water where mosquitoes breed, using mosquito-proof netting over outdoor enclosures, and avoiding peak mosquito activity times when rabbits are outdoors can reduce transmission risk. Flea prevention is critical, as rabbit fleas are highly efficient vectors of the virus. Regular treatment with rabbit-safe flea prevention products, which do not include fipronil products like Frontline that are toxic to rabbits, protects against this vector. Indoor housing during peak vector seasons, typically late summer through fall, significantly reduces exposure to mosquito-borne transmission.

Environmental prevention strategies reduce the overall risk of exposure to the Myxoma virus. Indoor housing provides substantially more protection than outdoor housing, eliminating most exposure to insect vectors and wild rabbits. If outdoor access is provided, enclosures should be designed to minimize insect access through the use of fine mesh netting. Wild rabbits should be prevented from accessing areas where domestic rabbits live or exercise, as they serve as a reservoir for the virus. Housing should be kept clean and dry, reducing attractions for insects. Geographic considerations matter, with higher risk in rural areas with large wild rabbit populations compared to urban locations.

Biosecurity measures prevent introduction and spread of myxomatosis within rabbit populations. New rabbits should be quarantined for at least two weeks before introduction to existing rabbits, and ideally should come from known myxomatosis-free sources with documented vaccination. Shows, fairs, and other events where rabbits from multiple sources gather create transmission opportunities and may best be avoided in endemic areas. Equipment, cages, and supplies should not be shared between different rabbit populations without thorough disinfection. Hands should be washed thoroughly between handling different groups of rabbits. If myxomatosis is confirmed in a rabbit, strict isolation and appropriate biosecurity measures are essential to prevent spread to other rabbits.

Early detection and response to myxomatosis in an area help protect individual rabbits and populations. Rabbit owners should be aware of the clinical signs of myxomatosis and seek immediate veterinary attention if symptoms are observed. Any confirmed cases should be reported to appropriate veterinary authorities if required by local regulations. Awareness of disease activity in wild rabbit populations provides information about local risk levels. Prompt isolation of any rabbit suspected of having myxomatosis prevents spread to other rabbits while diagnosis is confirmed. Working with a rabbit-savvy veterinarian to develop a prevention plan appropriate for the local situation provides the best protection for pet rabbits in endemic areas.

Daily management for rabbits in myxomatosis-endemic areas emphasizes prevention and early detection rather than management of established disease, given the extremely poor prognosis once infection occurs. Owners should incorporate regular health monitoring into daily routines, checking eyes, nose, and overall appearance for any changes that could indicate early illness. Vaccination status must be maintained current with appropriate boosters, and records should be kept. Vector prevention measures should be consistently applied, including flea treatment and mosquito protection. During high-risk seasons, typically late summer and fall, extra vigilance and possibly increased indoor time provide additional protection.

Home environment modifications in endemic areas focus on reducing exposure to vectors and potentially infected wild rabbits. Housing should be designed or modified to exclude mosquitoes through the use of fine mesh screens over any openings. Indoor housing or enclosed outdoor areas provide better protection than open outdoor access. The area around rabbit housing should be maintained to reduce mosquito breeding sites by eliminating standing water in containers, gutters, or low spots. Wild rabbits should be excluded from gardens and areas where domestic rabbits spend time through appropriate fencing. Careful attention to these environmental factors can substantially reduce transmission risk even in areas where myxomatosis is common.

Quality of life for rabbits in endemic areas can be maintained through thoughtful management that balances disease prevention with the rabbit's need for space, exercise, and enrichment. Indoor housing need not be restrictive if adequate space and stimulation are provided. Exercise areas can be enclosed with mosquito netting to allow supervised outdoor time during lower-risk periods. Enrichment activities, social interaction, and proper nutrition support overall health and immune function that may help if exposure does occur. The goal is to minimize disease risk while still providing the rabbit with a fulfilling, happy life.

Ongoing monitoring in endemic areas includes both individual rabbit health observation and awareness of disease activity in the region. Any unusual deaths in wild rabbit populations may indicate circulating virus and should prompt increased vigilance. Veterinary authorities or local rabbit clubs may provide information about myxomatosis activity in the area. Regular veterinary visits allow professional health assessment and provide opportunities to discuss risk levels and prevention strategies. Any symptoms suggesting possible myxomatosis should prompt immediate veterinary consultation and isolation of the affected rabbit.

Caregiver resources for rabbit owners in myxomatosis-endemic areas include veterinary support, rabbit welfare organizations, and community networks. Rabbit-savvy veterinarians can provide guidance on vaccination protocols, vector control, and regional risk assessment. Organizations like the House Rabbit Society and local rabbit rescue groups offer information and support for rabbit owners dealing with disease concerns. Online communities connect owners facing similar challenges and share practical prevention strategies. Understanding the regional epidemiology of myxomatosis through veterinary and agricultural authority resources helps owners make informed decisions about their rabbits' care and protection.

All domestic rabbit breeds are equally susceptible to myxomatosis, as the disease affects all descendants of the European rabbit regardless of breed characteristics. The Myxoma virus causes severe disease in all domestic rabbits because they share the same basic susceptibility as their wild European rabbit ancestors, which evolved without exposure to this South American virus. No breed has natural resistance or immunity to myxomatosis, and no breed-specific variations in disease severity have been documented. Giant breeds, dwarf breeds, lop breeds, rex breeds, and all other recognized breeds face equivalent risk when exposed to the virus. Mixed-breed and rescued rabbits of unknown heritage are equally susceptible.

Risk for myxomatosis is determined by environmental and management factors rather than breed. Outdoor rabbits face substantially higher risk than indoor rabbits due to greater exposure to insect vectors. Rabbits in rural areas with large wild rabbit populations have more exposure opportunities than urban rabbits. Unvaccinated rabbits are at high risk regardless of breed, while appropriately vaccinated rabbits have significant protection. Geographic location is perhaps the most important factor, as the disease is endemic in some regions and absent from others. Age and overall health status may influence outcomes if infection occurs, with healthy adult rabbits potentially having slightly better survival chances than very young, old, or immunocompromised individuals.

Prevention recommendations apply equally to all breeds and focus on the modifiable risk factors that influence exposure. Vaccination is recommended for all rabbits in endemic areas regardless of breed. Vector control measures should be implemented for all rabbits, with particular attention during high-risk seasons. Indoor housing or protected outdoor enclosures benefit all breeds equally. Any rabbit, regardless of breed, should be monitored for signs of illness and receive prompt veterinary attention if symptoms develop. Breeders, rescue organizations, and individual owners should all implement appropriate prevention strategies based on their geographic location and local disease risk.

Conditions that commonly co-occur with or develop secondary to myxomatosis include bacterial infections that exploit the immunosuppression and tissue damage caused by the virus. Secondary bacterial pneumonia frequently develops, with Pasteurella multocida and other respiratory pathogens opportunistically infecting the compromised respiratory tract. Bacterial conjunctivitis overlying the viral damage to ocular tissues worsens the eye discharge and inflammation. Skin infections may develop in areas of myxomatous damage. Gastrointestinal stasis commonly develops secondary to the anorexia and general malaise caused by the disease, creating an additional life-threatening complication that requires separate management. These secondary complications often contribute significantly to mortality and morbidity even in rabbits that might otherwise survive the viral infection itself.

Conditions with symptoms that might initially be confused with myxomatosis include other causes of facial swelling and conjunctivitis. Severe bacterial conjunctivitis from Pasteurella or other organisms causes eye discharge and swelling but typically less dramatically than myxomatosis and without systemic signs. Dental abscesses can cause facial swelling but in a more localized pattern. Allergic reactions might cause facial swelling but would be acute in onset and not progressive. Treponematosis, or rabbit syphilis, causes facial lesions but with a different appearance. Insect stings or bites could cause localized swelling. In endemic areas, however, any rabbit presenting with bilateral severe eyelid swelling and conjunctivitis should be considered potentially infected with myxomatosis until proven otherwise.

Other infectious diseases of concern in rabbits that may occur in the same populations or require similar prevention approaches include rabbit hemorrhagic disease, caused by caliciviruses that can cause sudden death in rabbits. Modern combined vaccines protect against both myxomatosis and rabbit hemorrhagic disease virus, making vaccination an efficient approach to preventing both serious viral diseases. Pasteurellosis, caused by the bacterium Pasteurella multocida, causes respiratory and other infections and may complicate myxomatosis cases. Encephalitozoon cuniculi, a parasitic organism, causes neurological and other disease in rabbits and may be a consideration in rabbits showing various symptoms. Comprehensive preventive care including appropriate vaccinations, parasite prevention, and good husbandry protects against multiple diseases.