Pasteurella

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Dacryocystitis or weepy eye is a common inflammatory condition of the tear ducts. It can occur in one or both eyes and is often associated with other issues such as conjunctivitis. Weepy eye is often caused by dental disease such as an abscessed tooth, foreign body tear duct blockage such as hay, a bacterial infection such as Pasteurella, tear duct trauma, eyelid wounds or respiratory infections.

Weepy eye is often accompanied with other symptoms such as decreased appetite, weight loss, depression, lethargy, matted or crusted fur around the eyes, rubbing their eyes with their front feet which can also cause matted or crusted fur on the front feet, swelling under or around the eyes, fur loss around the eyes, tear-stains on their fur, red and swollen eyes, conjunctivitis. Watch for wet fur around the eyes or on the face, and/or on the front paws. Also watch for green, gray, white or yellow eye discharge.

Pasteurellosis

Pasteurella is a gram negative rod bacteria. It is an opportunistic bacteria when in the body, which means that the bacteria is normal and in certain parts of the rabbit’s body. If, however, it relocates to another part of the body, it is capable of causing disease. In rabbits, pasteurella is a major cause of respiratory diseases. If your rabbit has a respiratory disease, pasteurella multocida should be considered but never assumed to be the cause of a respiratory disease. Several other causes of respiratory disease are Bordetella bronchiseptica, Staphylococcus, Pseudomonas, or Pasteurella multocida.  Pasteurella is one of the common causes of rabbit “snuffles” or respiratory infections. Interestingly, some rabbits exposed to pasteurella resisted the infection, spontaneously eliminated the infection, became subclinical carriers, developed acute disease (a bacteremia or pneumonia) or developed chronic disease.

There are several serotypes of this bacteria, labeled A, B, C, D, E, or F. The way this bacteria is more or less virulent depends on properties of the bacteria, such as adhesions, phagocyte resistance, endotoxins, exotoxins, and iron regulation. The type A strains are more likely to cause infection in the respiratory tract and are commonly seen. The type D strains are significantly more pathogenic and cause bacteremia (bacterial infection that goes to the bloodstream and spreads through the entire body) more often.   One of Pasteurella’s properties is that it has developed a thick capsule which prevents the bacteria from being eaten. Type D actually can avoid being broken down because it can resist bactericidal activity.

Transmission of pasteurella is by aerosol from acutely affected rabbits, by direct contact with affected rabbits, or by fomites (things like towels, blankets, or other things that are carried between the affected rabbit and a healthy rabbit). The bacteria enters the body through the nares or wounds. Rarely, venereal (sexual) transmission can occur with genital infections. If the body does not resist the infection, then the bacteria colonizes the nares and may cause production of a nasal discharge. The period of time between infection and showing signs of that infection is difficult to define because many rabbits are subclinical carriers of the infection, which means they may not show signs of the infection at all. In experimental studies, rhinitis (inflammation and infection of the nasal passages) occurred 1-2 weeks after intranasal inoculation, suggesting that the incubation time of this infection is 1-2 weeks. Once the bacteria becomes established in the nasal passages, the infection spreads to nearby tissues. Spreading hematogenously (by bloodstream) also can account for infection that reaches the internal organs, lungs, and middle ears.

Pasteurella is a commensal organism on mucous membranes, but can exhibit pathogenicity (infectious nature) under conditions of immunodeficiency and stress in the host. Nutritional, environmental, managerial, or social changes may predispose a rabbit to disease, as may infection from something else at the time of pasteurella infection, and physical or chemical injury to the mucosa. In disseminated pasteurellosis (pasteurella that is spread widely over the whole body), fever enhances the immune system response and increases survival. At this time, there is no vaccine available for rabbits.

Forms of pasteurellosis are varied. They can be signs of an upper respiratory tract disease (rhinitis, sinusitis, conjunctivitis, lacrimal duct infection), otitis, pleuropneumonia, bacteremia, abscesses of subcutaneous tissues or internal organs, bones, joints, and genitalia.

Affected rabbits present with audible respiratory noises, infection of nasal lacrimal duct may extend to the conjunctiva. Affected rabbits make audible noises and have bouts of sneezing. Conjunctivitis may sometimes be present. Infection can spread from the nares to the middle ears through the eustachian tubes. Otitis can also present where there is purulent white debris. The more pathogenic strains of pasteurella are likely to spread by the bloodstream (hematogenously) causing acute generalized disease, fever, and sudden death.

Diagnosis is made by isolation of the bacteria. This requires a culture before using antibiotics. Once antibiotics have begun, bacteria may be difficult to grow. A swab of the nasal cavities is taken. Also, serologic testing from a sample of blood is used. It is helpful in detecting internal infections or subclinical carriers.   After the culture returns, we will determine what antibiotic is the best to treat pasteurella based on what the bacteria is sensitive to.

Once the culture returns, your pet is placed on the appropriate antibiotic based on the sensitivity and your pet is rechecked several weeks later to determine if the infection is gone or still present.
Works Cited:

Pasteurellosis affects the upper respiratory tract and can lead to eye infections, as the Pasteurella bacteria tend to reside in the nose, lungs and eye membranes. This bacteria can be present for many months without causing any discomfort or symptoms, but when a rabbit becomes stressed or sick, Pasteurella bacteria can flourish. The first symptom is usually "snuffles," but it can lead to a secondary eye infection as well. See the more in-depth pages on Pasteurella.

Pasteurellosis (Pasteurella multocida infection)Pasteurella multocida is bacteria that commonly causes abscesses, respiratory infections, and chronic inflammatory disease in rabbits. It can infect the nasolacrimal (tear) ducts, eyes, ears, and nose, and can cause abscesses of tooth roots, bones (particularly the jaw), skin, tissues under the skin, and internal organs. This organism commonly causes an upper respiratory tract infection often called snuffles which frequently occurs in young rabbits.
Many cases of snuffles are mild, involving slight ocular or nasal discharge and sneezing and, if caught early, can be effectively treated or managed. If left untreated, this infection can progress to become severe, chronic, and potentially fatal. A swab for bacterial culture and antibiotic sensitivity testing can be taken of ocular or nasal discharge to help guide treatment. Treatment usually involves either oral or injectable antibiotics, given for a minimum of 2-4 weeks. In some cases, treatment can be required for months depending on the response to therapy.
Certain oral antibiotics, especially oral penicillin and similar drugs, can be fatal to rabbits. These antibiotics upset the normal gastrointestinal bacteria, leading to overgrowth of toxin-producing bacteria, diarrhea, dehydration, and death and should never be used in rabbits. There are safe oral and injectable antibiotics prescribed by veterinarians to treat this infection in rabbits, but none is leads to a definitive cure. Eye drops and nose drops, as well as oral anti-inflammatory drugs, may be used in conjunction with other antibiotics, as prescribed your veterinarian.
"Pasteurella multocidacan infect the tear ducts, eyes, ears, and nose, and can cause abscesses of tooth roots, bones, skin, tissues under the skin, and internal organs."Rabbits with abscesses in or under the skin, in the jaw, or in an internal organ often require surgery to remove the abscess. Abscesses in the middle ear (causing balance problems), eyeball (causing blindness) or in bones or major organs or often difficult to treat and may recur, even with surgery.
All rabbits carry Pasteurella organisms, but only some rabbits will manifest disease (their immune systems generally keep the organisms in check). Stresses such as poor nutrition, change in diet, introduction of a new pet or person in the house, overcrowding, environmental stresses, immunosuppression, or the presence of other disease, may trigger clinical signs. Many rabbits are chronically infected. The disease is easily transmitted between rabbits through direct contact with infected rabbits’ nasal or ocular discharge, contact with pus from an abscess, or contaminated items such as bedding and food and water bowls. New rabbits should be isolated (for about one month) before being introduced to existing pets. Even with successful medical or surgical treatment, relapses may occur if your rabbit is exposed to stressful situations. Be sure to have your rabbit checked annually by a veterinarian to keep him as healthy as possible to minimize problems with pasteurellosis.

PasteurellosisPasteurellosis is common in domestic rabbits. The etiologic agent is Pasteurella multocida, a gram-negative, nonmotile coccobacillus. Rabbits will usually become infected with P multocida immediately after birth, and the prevalence of colonization increases with age until about 5 months. Most adult rabbits are believed to be infected with P multocida. It is highly contagious and transmitted primarily by direct contact, although aerosol transmission may also occur.
In conventional colonies, 30%–90% of apparently healthy rabbits may be asymptomatic carriers. This is important to consider when nasal cultures are collected, because not every positive result indicates a pathologic condition.
This bacteria is not specific to rabbits but affects other animals as well, including dogs, cats, poultry, and domestic livestock. In case of a sudden Pasteurella outbreak, immediate medical attention is required for containment of the disease. The investigation of the case should include factors that could have contributed to the problem and any aspects that could be causing stress and immune suppression in the affected rabbits. To get a true representative culture of the nasal bacterial fauna, the rabbit needs to be heavily sedated or anesthetized and a deep nasal culture obtained by introducing the swab relatively far into the nasal opening. Several barrier colonies of laboratory rabbits have been established as Pasteurella-free.
Clinical Findings of Pasteurellosis in RabbitsPasteurellosis presents with a variety of clinical symptoms, including rhinitis, pneumonia, abscesses, reproductive tract infections, torticollis, otitis media/interna and septicemia. Rabbits may develop Pasteurella septicemia and die acutely without any clinical signs. Necropsy findings of septicemia cases may reveal only congestion and petechial hemorrhages in multiple organs.
Rhinitis (snuffles or nasal catarrh) is an acute, subacute, or chronic inflammation of the mucous membranes of the air passages and lungs, induced primarily by Pasteurella, but Pseudomonas spp, Bordetella bronchiseptica, Staphylococcus spp, and Streptococcus have also been isolated. The initial sign is a thin, serous exudate from the nose and eyes that later becomes purulent. The fur on the inside of the front legs just above the paws may be matted and caked with dried exudate, or this area may be clean with thinned fur as a result of pawing at the nose. Infected rabbits usually sneeze and cough. In general, snuffles occurs when the resistance of the rabbit is low. Recovered rabbits are likely carriers. Pneumonia can ensue.
Pneumonia is common in domestic rabbits. Frequently, it is a secondary and complicating factor in the enteritis complex. The cause is typically P multocida, but other bacteria such as Klebsiella pneumoniae, Bordetella bronchiseptica, Staphylococcus aureus, and pneumococci may be involved. Upper respiratory disease (snuffles, see above) is often a precursor of pneumonia. Inadequate ventilation, sanitation, and nesting material are predisposing factors. The number of cases of pneumonia is directly proportional to the level of ammonia in the cage, hutch, or rabbitry. Ventilation is of utmost importance to provide good air quality. Affected rabbits are anorectic, listless, dyspneic, and might have a fever. Treatment should include systemic antibiotics, optimally based on a culture and sensitivity, because of possible resistance to common pathogens. The rabbits are usually dehydrated, and supportive care with hydration and syringe feeding is often necessary as well. Topically administered ophthalmologic antibiotic products instilled into the nostril can also be beneficial. Necropsy reveals bronchopneumonia, pleuritis, pyothorax, or pericardial petechiae. Because rabbits commonly harbor Bordetella bronchiseptica in their upper respiratory tract, rabbits and guinea pigs should not be housed together, because guinea pigs are very susceptible to a severe pneumonia caused by Bordetella.
Otitis media or interna (“wry neck” or head tilt) results from infections with various agents. P multocida was reported to be isolated from 97% of cases of otitis media, including clinical and subclinical cases. B bronchiseptica and staphylococci were also found in 5%–10% of cases. An accumulation of pus or fluid in the middle or inner ear causes the rabbit to twist its head, eg, “wry neck” or torticollis. However, not all rabbits with middle ear infections show torticollis. Longterm antibiotic treatment is required for drug penetration into the affected area. Antibiotic therapy may only prevent worsening of clinical signs, and the prognosis is guarded with medical therapy alone. A bulla osteotomy is often indicated when medical management of otitis media and interna fails. A total ear canal ablation in rabbits is not recommended because the pathophysiology of otitis in rabbits is very different from that in dogs, in which a total ear canal ablation is often performed. If drainage of the cerumen is required, a simple stoma surgery at the base of the ear canal will be enough to facilitate the opening of the ear canal. Proper imaging of the ear lesions is indicated before surgery. Often, a CT scan of the head will help to identify the lesion and potentially help to differentiate otitis media/interna from intracranial disease in cases of torticollis (eg, Encephalitozoon cuniculi infection).

Stoma surgery for otitis externaCOURTESY OF DR. JOERG MAYER.
Conjunctivitis and dacryocystitis (weepy eye) is a common problem in rabbits. Predisposing factors include mechanical irritation, eyelid diseases, and dental disease. Conjunctivitis in rabbits may be associated with other disease processes, especially dacryocystitis. The most incriminated cause of conjunctivitis is P multocida; however, this may be only a secondary infection. Primary infections are less common than opportunistic infections. Transmission is by direct contact or fomites. Affected rabbits rub their eyes with their front feet. Bacterial conjunctivitis can be treated with topical chloramphenicol, ciprofloxacin, or gentamicin combined with systemic broad-spectrum antibiotic therapy if topical treatment alone is ineffective.
Dacryocystitis and acquired nasal duct obstruction may arise from chronic rhinitis that travels up the nasolacrimal duct to the eye or occasionally from dental disease such as tooth root inflammation or abscessation. Dacryocystorhinography or injection of contrast material into the lacrimal punctum will provide good radiographic detail of the duct throughout its course and show the site of obstruction. In long-standing cases of dacryocystitis and conjunctivitis, the punctum and segments of the nasolacrimal duct may progressively narrow and be replaced with scar tissue until they are irreversibly obstructed. To relieve discomfort and inflammation associated with these conditions, the use of topical nonsteroidal anti-inflammatory ophthalmic preparations such as flurbiprofen can be considered. Systemic NSAIDs such as meloxicam should also be used. Treatment can include gentle saline flushing of the duct through the nasolacrimal punctum, but care is warranted to not damage the nasolacrimal duct during flushing. Any mechanical damage to the fragile tear duct can result in permanent epiphora, and owners should be advised accordingly.
Conjunctivitis also accompanies rabbitpox and myxomatosis.
Subcutaneous and visceral abscesses caused by P multocida may be clinically silent for long periods and spontaneously rupture. When bucks penned together fight, their wounds frequently develop abscesses. Abscesses in rabbits are treated differently than abscesses in cats; rupture or drainage via Penrose is not the recommended course. Thick-walled abscesses should be surgically excised en bloc if possible. Open wounds should be debrided or curetted, marsupialized, and left to heal by second intention. Facial abscesses are often related to dental disease. Drainage of the abscess accompanied by systemic antibiotic therapy based on culture and sensitivity tests has been successful, although recurrence can be common.

Purulent material from abscessCOURTESY OF DR. JOERG MAYER.
Pasteurella can cause genital infections, but several other organisms also may be involved. The spirochete Treponema paraluiscuniculi is the causative agent of rabbit syphilis. Genital infections are manifest by an acute or subacute inflammation of the reproductive tract and most frequently are found in adults, more often in does than bucks. In the case of Treponema, a severe conjunctivitis or dermatosis between the toes can also be a key clinical sign. If both horns of the uterus are affected, the does often become sterile; if only one horn is involved, a normal litter may develop in the other. The only sign of pyometra may be a thick, yellowish gray vaginal discharge. If bloody discharge from the vulva is observed and a large uterine horn can be palpated, uterine adenocarcinoma should be included in the differential diagnosis. Bucks may discharge pus from the urethra or have an enlarged testicle. Chronic infection of the prostate and seminal vesicles is likely, and because venereal transmission may ensue, it is best to cull the animal in a production colony. Surgical removal of the infected reproductive organs in conjunction with antibiotic therapy is indicated for pet rabbits. The contaminated caging and its equipment should be thoroughly disinfected.

Blepharitis caused by TreponemaDiagnosis of Pasteurellosis in Rabbits

Combination of clinical signs, bacterial culture, and serotyping

A diagnosis of pasteurellosis should not be made solely on the presenting signs, but should include bacterial culture and blood work (CBC and blood chemistry profile). In severely affected cases, more advanced diagnostic tests such as radiography, ultrasonography, or a CT scan may also be needed.
Carriers of P multocida can be identified by an indirect fluorescent antibody test on nasal swabs. A technique that uses small, saline-moistened, pediatric nasopharyngeal swabs has proved superior to the standard, larger nasal swab. The swab is directed medially through the external nares past the turbinates and onto the dorsal surface of the soft palate; sedation is recommended. The swab is then retracted and can be used in the fluorescent antibody test or plated onto a culture medium. An ELISA test to detect antibodies against P multocida may also help detect carriers.
PCR can discriminate between different isolates and is commercially available. It is important to remember that Pasteurella can be sampled from a large percentage of clinically normal rabbits, and culture results must be interpreted carefully and in combination with the clinical signs and the antibiogram from sensitivity testing. Not every strain of Pasteurella is pathogenic. Five serotypes (strains) of Pasteurella have been described, with two of them most commonly involved in pathologic conditions in rabbits. The serotype, identified during a culture and sensitivity test, is tested to determine the most effective antibiotic.
Treatment and Control

Antimicrobial treatment may help control signs but will likely not eliminate infection

Treatment is difficult and will most likely not eradicate the organism. Antibiotics seem to provide only temporary remission, and the next stress (eg, kindling) may cause relapse. Prolonged treatment for 6–8 weeks is often needed. Many of the newer antibiotics are already ineffective because of an increase in resistant strains. Before treatment, a culture and sensitivity should be done to determine the best antibiotic to use.
Antibiotics effective against Pasteurella include enrofloxacin, trimethoprim sulfa, chloramphenicol, penicillin G, and azithromycin. Very often, systemic antibiotic therapy can be augmented by local antibiotic therapy. Gentamicin ophthalmologic drugs instilled into the nostrils can supplement systemic antibiotics for treatment of upper respiratory tract infections. Fluoroquinolones are usually good drugs if no resistance has built up, which is unfortunately common. Oral medication is usually well tolerated and without adverse effects. In case of unsatisfactory results, doxycycline can be added, because both drugs appear to have a synergistic effect. Sometimes, amikacin or azithromycin must be used, based on culture results.
Although medication in the drinking water is not recommended because of the tainting of the flavor and potential underdosing, this is sometimes the only possible route to treat animals on a larger scale. Enrofloxacin (200 mg/L of drinking water for 30 days) can be effective for upper respiratory P multocida infections. Procaine penicillin (60,000 IU/kg/day, SC, for 10–14 days) is also recommended for individual rabbits, but caution is warranted, because deaths from enterotoxemia can follow if the drug is accidentally given orally.
Additional treatments may include anti-inflammatory drugs, careful flushing of the nasolacrimal duct, nebulization therapy, ear and eye drops, administration of fluids, and surgery.

Culture swabCOURTESY OF DR. JOERG MAYER.
Two methods to free a production colony of Pasteurella have been reported. The first involves culture and culling of positive animals; once the colony is Pasteurella-free, it must be maintained in isolation. In the second method, pregnant does past kindling are treated with enrofloxacin. While does remain Pasteurella-culture positive, the kits remain Pasteurella-culture negative. Carriers can be identified by an indirect fluorescent antibody test on nasal swabs.
Key Points

Pasteurella

Pasteurella

Pasteurellosis

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