News Stories

Donors help fund ongoing research into 'Peregrine syndrome'

January 2012

AVS would like to thank the Hawk Board, Honeybrook Animal Foods, Falcon Mews, M+J Raptors, Mark Stidworthy MA VetMB PhD MRCPath MRCVS, Michael Lierz Prof. Dr med vet, DZooMed, DipECZM, DipECPVS, Dr. Akbar Dastjerdi and Dr. Tristan Cogan for their help and support with ongoing research into a wasting syndrome affecting captive peregrine falcons.
To date this disease has affected a number of falcons up and down the country (and anecdotally other parts of Europe) and AVS among other avian vets, pathologists and researchers have been gathering data and pooling experiences to try and get a better handle on this emerging disease.
We do not as yet have a definitive diagnosis but with falconers and breeders continued help in submitting cases for investigation we are slowly making progress.
What follows is a summary of the findings and information we have available at the time of writing.

1. From our personal observations this syndrome seems only to affect peregrines or peregrine hybrids even within multi-species collections.
2. Clinical signs include; general poor condition, weight loss despite eating excessively, screaming, mucoid/slimy diarrhoea, pale feet, cere and talons (Figs 1 and 2), excessive drinking and vomiting, sadly in many cases progressing to death despite culture based antibiotic treatment.
3. Some birds with aggressive supportive therapy improve and may even breed, but recurrent relapses are typical.
4. Despite countless faecal samples and cultures no single bacteria, yeast or parasite has been consistently identified across the board suggesting that those pathogens found are secondary invaders to an already inflamed/damaged gut.
5. We have recently received results from the virologists on both tissue and faecal samples of affected birds. Viral chip technology that searches for any viral DNA present in the samples and compares it to a data base of nearly 2000 known viruses, has failed to identify a causal virus in any samples submitted over the past year.
6. A separate team at Bristol University which has been looking at tissue samples of both affected and 'normal peregrines' (wild casualties that have been euthanized on humane grounds) has demonstrated changes consistent with post infectious inflammatory bowel disease (IBD). This is a similar condition to ulcerative colitis in people where a historic intestinal insult, be it viral, parasitic or toxic may result in an 'autoimmune reaction' where the bird develops antibodies to its own intestinal lining. This damages the gut allowing secondary infections to proliferate. It is thought this occurs because 'antigens' or protein markers on certain infectious agents (salmonella for example) may resemble similar structures found on intestinal cells. As such when antibodies are made in response to infection, they are then stored in the immune systems 'memory' as a permanent defence mechanism against future challenge. When under stress or hormonal influences (in a paper on ulcerative colitis in women, flare ups often occur after giving birth and rarely during pregnancy) the body can mistakenly identify intestinal cells as invading infectious agents and attack it accordingly. Also in mammals certain foods can trigger episodes. As such when a bird demonstrates clinical signs associated with certain food items it is assumed this must be carrying 'the virus'. It is equally possible however that certain proteins cause flare ups and others don't, hence the possible response to exclusion diets (all rat for example).
Based on the above our current working hypothesis is that a historic gut insult be it a bacteria, virus, parasite or toxin results in post infectious IBD, which (as in humans) is then likely to be a lifelong problem with 'flare ups' managed by identifying and removing apparent trigger factors (certain foods, parasites etc) in conjunction with supportive fluids, nutrition and medication.

The problem we are up against is by the time obvious clinical signs are apparent the inciting cause is likely long gone.
As this syndrome seems to be overrepresented on older birds it may be that chronic or repeated low level intestinal insults by one or a combination of the above eventually leads to disease.


Current recommendations

If a falcon is displaying such symptoms we would advise you contact your avian veterinarian ASAP as other easily diagnosed conditions such as coccidia (Fig 3) can produce similar signs and are very easily treated. In addition collecting samples as early as possible in the process increases the likelihood of recovering causal agents. Probiotics have been shown to help maintain a healthy gut flora and may offer some protection against IBD. As such we have been using such products on a preventative basis in collections of breeding falcons. If a falcon seems to have diarrhoea following the ingestion of certain food items or groups (provided other infectious causes have been ruled out) it may be worth trying an exclusion diet as discussed above. If things improve on a novel protein it maybe this bird has a 'sensitivity' or 'intolerance' to certain food items that may contribute to the development of IBD. As affected falcons appear to drink copiously, it is recommended fresh water is available at all times.

We will endeavour to keep you informed of any future developments via our website, the Hawk Board and Falconry club literature and you can make a donation to the Hawk Board's raptor research fund via their web site. www.hawkboard-cff.org.uk