Sinus Infection in Rabbits

A sinus infection is basically inflammation of air sacs that surround the sinuses or nasal cavity in an animal - in this case, your rabbit.  What you will likely see in your rabbit is pretty much what you see in other animals and humans when an upper respiratory infection is present, namely: nasal discharge, sneezing or other audible respiratory-type noises, discharge from the eyes (like pink-eye in humans), crusted or distorted nose or nostrils, matted fur, torticollis (head twist or list to one side caused by a muscular contraction), tachypnea (rapid, shallow breathing), dyspnea (labored or difficult breathing), lethargy (decreased activity, energy and enthusiasm) and anorexia (eating disorder that affects diet).  Pneumonia is a common progression from the bacterial causes of sinus infections.  

Because nearly all rabbits are carriers of the Pasteurella multocida organism and because this particular organism is somewhat related to the mucous membranes that make up the respiratory tract, this opportunistic organism results in a bacterial-type infection that generally affects animals as a condition called pasteurellosis.  This can be transferred to humans via scratches or bites, making this highly contagious by virtue of contact.

The simple veterinary definition for sinus infection is an inflammation of air-filled areas that surround the rabbit’s sinus or nasal cavity.  This condition is similar to rhinitis, which is one of the diagnoses that comes from the bacterial infection caused by this inflammation.

What you will see in your rabbit will likely be a combination of the following visual signals:

• Nasal discharge - Will likely be thin initially but will progress to purulent (containing pus or mucus)
• Eye discharge - Will likely resemble that seen coming from the nose and will progress similarly
• Sneezing and other audible respiratory sounds (coughing)
• Matted fur - This will likely be found inside the front legs, just above the paws, fur may also be coated or crusted with dried material discharged from eyes and nose
• Clean, thinning fur in the same location which results from pawing at the nose.
• Head tilt or “wry neck” indicates some middle ear involvement
• Breathing issues - Labored, difficult, rapid or shallow breathing
• Lethargy that causes the animal to lay around and be uninterested in the normal activities
• Anorexia may be noted in the eating habits

The above symptoms may begin mildly and become a moderate or severe stage as the infections progresses.

Types 

Some of the ways sinus infections can present are listed below.  These are based upon the organism which is at the root of the infection and the degree of advancement:

• Rhinitis
• Pneumonia
• Otitis media or interna (ear involvement)
• Conjunctivitis and dacryocystitis (“pink-eye” and clogged nasal lacrimal duct)
• Abscesses
• Genital infections

There are a number of potential causes of sinus infection in rabbits.  Some of them are preventable and controllable while others are not. The causes of the sinus infection are as listed:

• Bacteria like Pasteurella multocida, Pseudomonas, Bordetella Bronchiseptica, Staphylococcus and Streptococcus
• Inadequate ventilation that causes increases in ammonia due to inadequate sanitation and nesting materials - these conditions predispose the animal to pneumonia and other upper respiratory infections
• Viruses like myxoma virus and herpes virus
• Trauma
• Allergies
• Chemical exposure
• For those rabbits making the transition from garden to home environments, things like changes in temperatures, ventilation, humidity and environmental pollutants become potential causes
• When stressed, the animal experiences irritation or inflammation of the airways or even immunosuppression both of which can cause the microbial flora of the respiratory system to become pathogenic or disease-causing

Your veterinarian will need to evaluate the clinical signs she notes on examination.  The next step will be to attempt to isolate the causative bacteria (most often Pasteurella multocida) via indirect fluorescent antibody nasal swab testing and culture sensitivity.  This is done by inserting a swab into the nostris) of your rabbit for the purpose of collecting specimens of the organisms present there.  It may be necessary to sedate your pet to accomplish this task.  The swab is then evaluated by fluorescent antibody review either from the swab directly or on a plate of culture medium. The organisms will show up under the fluorescent review and can then be identified. 

It is important to note here that not all strains of Pasteurella cause disease or infection since some otherwise clinically normal rabbits are carriers of the organism. Once the organism responsible for the infection is determined, an effective treatment plan is then developed and utilized.

As with any infection, whether the subject is animal or human, it is important to determine the organism responsible before treatment can be developed.  In the case of bacterial infectives, one must also ascertain the most effective antibiotic medication and the most effective method of administration for the treatment of the condition.  Sinus infection in rabbits is difficult to treat and the treatments are not likely to completely eliminate the organism.  Antibiotics only have the ability to provide what could be called temporary remission at best, and, the next stress situation has the potential to enable a relapse of the infection.

Treatments with antibiotics could range from 6 to 8 weeks in duration.  Additionally, many of the newer antibiotics are already showing increased resistance to the various strains of the offending bacteria.  Culture and sensitivity testing will ultimately be needed so that the best antibiotic treatment can be initiated.  

Gentamicin ophthalmic drugs can actually be instilled into your rabbit’s nostrils to assist the systemic antibiotic treatment and this has been shown as a significant aid to the treatment plan for infections, especially those involving upper respiratory tract infections.  Some of the antibiotics that could be used are:

• Fluoroquinolones are good drugs as long as there is no evidence of resistance built up
• Doxycycline
• Amikacin
• Azithromycin

These medications will be prescribed based upon culture and sensitivity testing.

Isolate your pet until all other rabbits in the home have been treated or declared healthy. Carriers of Pasteurella, or others who may be coming down with the condition can be identified by having the veterinarian do the indirect fluorescent antibody test using nasal swabs. 

The mortality issues associated with sinus infection of rabbits is low, generally speaking.  Even if your rabbit suffers from chronic episodes, he can survive although if the disease is allowed to progress to a point at which it can spread to the lower respiratory tract, it can cause pneumonia which is more often to be fatal.