I'm guessing Mrs N means Infectious Laryngotracheitis, which has very similiar symptoms to Newcastle disease and to infectious bronchitis. All 3 of these diseases are highly contagious and lethal to a large percantage of the flock. Since this hen has always been off, I doubt that the others could be so healthy with her in the mix. There is a small chance she's a carrier, but where did she pick something up that didn't also hit the other birds? She would have had to have been infected as an egg or chick, not to have died in almost a year, and not to have done what a carrier does, spread the disease.(posted 9667 days ago)It is really tough to type and hang on to these heavy books at the same time but I'll try to run down the major symptoms of the 3 diseases so you can decide. And they are the 3 that had occured to me originally, but I decided things just didn't quite fit.
Infectious Laryngotracheitis. spreads rapidly. difficult breathing, bird extends head & opens mouth for each breath. rattling sound in windpipe-mucus obstruction. may throw head from side to side to dislodge mucus. coughing. tearing eyes. then it gets worse. can be prevented, no treatment
Infectious Bronchitis. also viral. can be transmitted by air. therefore most contagious respiratory disease of poultry. Specific symtoms don't differ from other respiratory diseases. nasal discharge, rattling, sneezing, coughing. gurgling windpipe. mortality may be high due to suffocation. poor egg shape and decreased production. bird should recover, may not be able to lay proper eggs. not much to do to treat.vaccines may or may not work, may cause more problems.
Newcastle. difficulty breathing. depression and weakness. twitching of head and neck. paralysis. at this point they recover or die. egg production stops (as it basically does in the above 2 also)Symptoms can also be or suggest infectious bronchitis, air-sac infection(crd), laryngotracheitis, avian encephalomyelitis, epidemic tremor. leucosis. nutritional defficiencies.
I'm going to stick with what I originally said. However I would be very interested to know what Mrs Ness has to say. Be interesting to hear what happens to the hen-who knows, I may owe you a flock of chickens when this is over. Gerbil