EGG DROP - THE SYNDROME, NOT THE SOUP...
Egg Drop Syndrome
by K. J. Theodore
If you have a serious problem with thin-shelled or shell-less eggs, or a marked reduction in egg production, then you could be dealing with EGG DROP SYNDROME. I would not worry about the occasional thin-shelled or shell-less egg that comes at either the beginning or the end of the production season, nor the occasional less-than-perfect egg that is produced by a young hen when she comes into ‘first egg’ (sexual maturity). Egg Drop Syndrome (EDS 76), should be considered though when you have a chronic problem in your flock in terms of egg quality or quantity – especially at the height of production.
EDS 76 is caused by a duck adenovirus and is typically spread vertically, although the incidence of lateral spread does exist. The virus affects the pouch shell gland, which is responsible for producing the eggshell.
EDS 76 is not typically a big problem with domestic ducks or geese, which are natural hosts, but when affected through drinking water contaminated by feces, chickens can experience a profound affect on their egg production. Although the virus doesn’t actually spread through the feces, what happens is that there could be exudates from the oviduct, which finds its way into the feces.
There are several things you can look for in the eggs that your hens produce to determine if you’re dealing with an EDS 76 problem in your flock.
A loss of pigment in an otherwise brown or dark-shelled egg is one. Thinning at the pole of the egg is another. This is when the egg appears normal except for an appearance of thinning or translucence at the large end of the egg. When pressure is applied, the shell will break at this point first. Eggs that are thin-shelled and fragile overall is also a sign. Sometimes these eggs will feel like sandpaper to the touch. The most noticeable signs though are in the soft-shelled, or shell-less eggs. Sometimes these are hard to detect because the hens typically eat these before you see them. Look for the shriveled membranes in their litter – they’ll leave those. Otherwise, check early in the morning before the hens have a chance to eat the shell-less eggs.
Although a loss of appetite and dullness can occur, affected hens typically remain healthy otherwise. It can become a serious problem for the breeder, but if you’re just keeping a little backyard flock for fun, then EDS 76 is not something that I would consider serious as a ‘pet owner’.
If you are a breeder and you have EDS 76 in your flock, then you can, over time, systematically eliminate the virus from your flock. Not all hens will actually receive the virus vertically, and as soon as you can identify them, you can slowly eliminate the problem. But while you’re undergoing this process, you must make sure that you don’t reinfect your flock through other means.
One way to reinfect the flock is to reuse the egg trays you used prior to identifying an EDS problem. The virus not only lives inside of the egg, but also on the outside of the shell. The virus transfers from the eggshell to the tray and then back again to a fresh egg placed in the same tray. If you’re serious about eliminating Egg Drop Syndrome, then you have to replace all of your trays with new ones. If you have plastic trays, you can use a disinfectant, such as Oxine, to disinfect them. You can also spread EDS 76 through needles that are not sterilized between uses. The infected egg itself is actually the most dangerous source of infection though.
Another way to prevent reinfection is to prevent wild ducks or geese from entering your yard and contaminating the water and ground with feces. Even newly adopted or purchased domestic ducks and geese should be kept from the chickens if you’re working on eliminating EDS 76 from your flock. Once you’ve established that the new ducks or geese are laying well, you can mix them into the flock. Remember though that EDS 76 is a latent virus that usually doesn’t affect egg quality until the hens are at their peak production. And remember, the most dangerous source of virus is an infected egg.
There is no known treatment for Egg Drop Syndrome. Some breeders simply live with the results of EDS 76 in their flock. Hens will appear healthy and happy whether they produce good eggs or not. Ducks that are infected and are hosts of EDS 76 show almost no signs of it and their eggs are usually good. This makes it even more difficult to identify the ducks or geese that are carriers.
Egg Drop Syndrome can be quite frustrating to the serious breeder. If it becomes a real problem for your breeding program, then vaccination is always an option. The vaccine lasts at least one year. Revaccination is usually necessary every year afterwards. Initial vaccination occurs between 14 and 16 weeks of age. Adults not previously exposed to EDS 76 can be vaccinated as well, but must receive a booster each year also. Most people find this to be quite an ordeal though when you consider the expense and the stress on the birds for something that is not life threatening, and does not carry any human health risk.
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