Panophthalmitis due to Pasteurella infection
©Dr David L Williams
Panophthalmitis due to Pasteurella infection
The term Pasteurella multocida, or simply Pasteurella spp (species), refers to a bacterial species that is commonly found in many animals, especially rabbits. Pasteurella spp infections can happen suddenly or be long-standing and constant and the bacteria can invade several body cavities.
What is pasteurellosis?
Pasteurellosis is a bacterial disease that can be a cause of nasal or sinus infections, ear or eye infections, pneumonia, or abscesses in bone, joints or internal organs in rabbits.
Snuffles is a general term used to describe a group of upper respiratory signs. Several different bacteria may be responsible for causing snuffles, but the most commonly occurring bacteria is Pasteurella spp.
Pasteurella spp commonly lives in the nasal cavity of many rabbits, but can also colonise in the middle ears, trachea, lungs, lacrimal ducts and genitals. Here it can reside for many months or even years without ever causing any clinical signs of disease.
Different strains exist, and some of these are zoonotic, which means they can be transmitted to humans.
What are the signs of pasteurellosis?
Many rabbits will carry Pasteurella spp without ever developing clinical signs.
The clinical signs of snuffles are varied in their appearance and severity. The common development of signs include a watery nasal discharge that will develop into a thick white/yellow discharge and sneezing, snuffling or increased respiratory noise, effort and rate.
Rabbits will often wipe their nose, eyes and face with the inside of their forelegs, which will lead to matting of the fur on the side of the legs. This is a tell-tale signs that the rabbit has a runny nose and or eyes. If the bacterium travels to the eyes, then conjunctivitis may be evident. It can also travel to the ears, causing infections and clinical signs may include head tilt, increased headshaking/scratching of the ears, rolling and circling, and general disorientation. There are other diseases that can also be responsible for these signs, such as Encephalitozoon cuniculi (E. cuniculi) for example, so it is important that your vet obtains a definitive diagnosis.
If the rabbit is suffering from a severe form of the bacterium, then they may also go on to develop other problems. Some rabbits have developed abscesses, which may be evident almost anywhere on the body; they will appear as swelling and if they are discharging, they will have a foul smell and be moist, making the fur matted. Some rabbits may be totally unaffected by them, for other they may be painful. Other rabbits may develop problems such as osteomyelitis (infection in the bone), meningitis (inflammation of part of the brain) or myocarditis (inflammation of the heart muscle).
Clinical signs seem to occur when a carrier rabbit is unwell or stressed for any reason. These may include pregnancy, lactation, overcrowding, bonding with another rabbit, loss of a companion, other illness that suppresses the immune system, and nutritional deficiencies.
How is pasteurellosis diagnosed?
It is important to get a definitive diagnosis, so appropriate treatment can be administered to have the best chance of being successful.
A deep nasal swab under sedation or anaesthesia can be taken for bacterial culture. Ideally the samples need to be taken prior to any antibiotic treatment being started, since this will alter the results. False negatives can also occur if the samples are not deep enough. The laboratory should be able to isolate the bacteria and identify which antibiotics the bacterium is sensitive to.
There are several other conditions that can cause clinical signs similar to those of pasteurellosis. Most importantly:
- Dental disease: especially if the nasolacrimal duct is occluded, as this will cause discharge from the eyes.
- Nasal foreign bodies: hay/grass seeds have been removed from rabbit's noses. Commonly this would only result in discharge from one of the nasal cavities; discharge from both would be uncommon.
- Other bacterium: these include Bordetella, Pseudomonas and Staphylococcus spp.
- E. cuniculi: this can be responsible for a host of clinical signs, including heat tilt, paralysis, uveitis, seizures, urinary incontinence and sudden death.
Can pasteurellosis be treated?
The usual course of treatment for pasteurellosis is with antibiotics. The treatment course may be anything from 14-30 days, or longer in some cases, such as recurring abscesses.
It is always a good idea to give the rabbit supportive treatment to prevent digestive upsets during antibiotic treatment. Where possible, injectable antibiotics should be used over oral; they will be better tolerated with fewer side effects.
What is the prognosis?
With the appropriate treatment, in many cases the clinical signs of the disease may disappear, but the bacteria are usually still present, only in smaller numbers. These may result in 'flare ups' of signs if the rabbit is placed under increased stress. Treatments are likely to need repeating and some rabbits may require prolonged treatment to try and get the condition under control.
Some rabbits do not respond to treatment, especially if the disease process has become chronic. If these rabbits are unable to have a good enough quality of life, then euthanasia should be considered.
How can I prevent my rabbit from developing the disease?
There are some things you can do to try and prevent your rabbit from getting signs of pasteurellosis, but these are likely to be limited.
The most important thing to do is to get a healthy rabbit in the first place. Rabbits that sneeze, have runny eyes or nose are best avoided, and any that have shared these rabbits' environments. However, as rabbits may show no signs and develop them later in life when exposed to increased stress, selecting a healthy looking rabbit is not fool proof for preventing the disease. As an extra precaution, all new rabbits brought into an environment with other rabbits should be quarantined for at least a month.
Always ensure that you keep your rabbit in spacious accommodation with plenty of exercise, with a rabbit companion, a suitable diet (grass/hay based) and regular health checks, ideally on an annual basis.
Before placing your rabbit into a boarding establishment, ask them what provisions they have for preventing the spread of disease. Pasteurellosis is highly contagious and can be spread in the air from sneezing rabbits and bodily secretions, therefore rabbits should be kept well away from each other.