Time to take a stand against Mycoplasma
Dr Ben South MRCVS
Shoots across the country are now at their busiest and at this time of year we see the greatest number of Mycoplasma outbreaks. This year has been no exception, with the highest level of outbreaks seen.
Mycoplasma or ‘Bulgy Eye’ is the common name for a wide range of specialist bacteria found across the animal kingdom in the respiratory tract. In pheasants we mainly see Mycoplasma gallisepticum (Mg). Within this group there are multiple strains that we can identify and often are geographically restricted.
Mg is the most common bacteria consistently identified in wild game birds in the UK and may exist in the respiratory system of birds undetected and without causing clinical disease. Mg is an opportunistic bacterium and will start replicating when its host is immunosuppressed. Damage to the upper respiratory system by common environmental viruses such as ART (Avian Rhinotracheitis) and IBV (Infectious Bronchitis virus) will be enough to allow Mg to multiply. We often isolate other opportunistic bacteria alongside Mg such as ORT (Ornithobacterium rhinotracheale). Immunosuppression can occur in wild game from chronically high stress levels from over shooting, high predation and competing for food resources. Poor nutrition and overall poor gut health can also cause a bird to be weak enough for Mg to develop.
The avian sinuses are a labyrinth of channels running from the nostrils through and around the orbit of the eye and down beneath the skull. When the delicate respiratory membrane becomes damaged and inflamed the resulting swelling appears in one place, and that is around the eye. The term ‘Bulgy Eye’ comes from this clinical sign and it is often associated with an Mg infection. As well as the eye swelling and sinusitis other clinical signs include sneezing, head shaking, eye rubbing, nasal and ocular discharge and ‘wet shoulders’ where the birds rub their irritated eye. It is highly contagious and is spread via open water sources, bird to bird contact and open feeders. To complicate matters, a bird that is Mg positive can pass the bacterium through to its young via the egg.
If birds are found with clinical signs then it is highly recommended you contact your vet to organise some diagnostic testing. Swabs may be taken to identify the presence of Mycoplasma via PCR. However, it would be more prudent to identify the bacterium via culturing. Positive cultures will allow for strain isolation testing and the potential to develop an autogenous vaccine for specific estates that incur regular reoccurrence of Mg infections year on year. Commercially available vaccines are used but are developed for commercial poultry and may not provide adequate cover. The BVPA (British Veterinary Poultry Association) are continuing their study into the epidemiology of Mg in game birds and it may be possible to join their diagnostic scheme. More information on this can be found at www.bvpa.org.uk.
Confirmed Mg outbreaks at this time of year are difficult to manage and I suggest getting diagnostic confirmation from your vet to be a top priority. It is imperative to identity what respiratory diseases are present now in order to evaluate and investigate the best prevention method for next season. Antibiotics will only help to alleviate symptoms and reduce shedding, leaving most birds as carriers. There are a few antimicrobial options but Aivlosin is the only licensed product for pheasants.
Preventative measures for Mycoplasma control, like many other diseases, is focused on good husbandry, the purchasing of clean stock and being strict with an all-in, all-out system. Culling of infected birds is advised as well as maintaining good biosecurity, especially considering where your beaters and picker uppers have been previously in the week. Alleviating stress will help prevent clinical outbreaks and I would consider resting areas of the shoot that do become infected.
There are currently discussions between the major organisations of the industry on how best to reduce this problem and St David’s is heavily involved in these projects. If you require any more information, please do not hesitate to contact our team of vets.
In brief: keep vigilant for clinical signs, diagnose and prevent.