Doing a necropsy at home?

[Sussex19]

I had a thread where I was wondering if my flock has Marek's, because of one of my hens going blind in one eye.
Since then, despite having lots of young pullets and cockerels, there have been no more symptoms of anything, so I'm hoping I'm in the clear. (Obviously not necessarily, but one can hope..)
This a autumn, I'm planning on culling that hen, and a couple of others, as they do not fit in with my goals.
Getting a proper test done is out of the question (due to cost and family reasons) so I was wondering if there is anyone on the forum who could teach me a bit about what to look for if I do my own necropsy?

 

[MysteryChicken]

@Eggcessive
@azygous

 

[azygous]

If you're expecting to see definitive signs of Marek's in a home necropsy, it's not possible to make that kind of diagnosis. My state lab tech even could not make a definite diagnosis on the two separate necropsies he did for me. The best he could do was tell me there was a preponderance of signs the chicken had avian leucosis.

The reason is that the signature tell for Marek's is inflammation of the sciatic nerve and it is nearly impossible for an amateur to detect. The other common avian virus is leucosis and it may be a bit easier if you find a grossly enlarged liver, especially if it has tumors.

I looked at the thread with the photos of the eye. It could be ocular Marek's, but usually, the colored part fades to a grey. If it is Marek's, and if it's one of the lesser contagious strains, your flock may have developed resistance and could escape ever becoming symptomatic.

If it were me in your position, I would proceed as if Marek's was unlikely. In the future, if another chicken shows signs of Marek's, then you might want to reconsider and get a neccrospy.

 

[Sussex19]

If you're expecting to see definitive signs of Marek's in a home necropsy, it's not possible to make that kind of diagnosis. My state lab tech even could not make a definite diagnosis on the two separate necropsies he did for me. The best he could do was tell me there was a preponderance of signs the chicken had avian leucosis.

The reason is that the signature tell for Marek's is inflammation of the sciatic nerve and it is nearly impossible for an amateur to detect. The other common avian virus is leucosis and it may be a bit easier if you find a grossly enlarged liver, especially if it has tumors.

Oh well, I guess I was being overly optimistic to think that I could do it.
I still need to cull her, and of cause don't want to sell her, so might as well still open her up and see if I can see anything wrong.

your flock may have developed resistance and could escape ever becoming symptomatic.

The thing is, I got my birds from 6 different places, including some from a different state (as fertile eggs) so resistance to the same strain seems unlikely.
Am I right in thinking this?

Thank you for your time and thoughts!
If I do find anything odd when I do the necropsy, would you mind taking a look if I get some photos?
It will still be a while, as my replacement pullets aren't fully grown yet.

 

[Eggcessive]

Can you post a picture of your chicken’s eye here? If you do a necropsy, take pictures of everything, including the liver, intestines, and other major organs. Take a picture of the abdomen as you open it, and organs can be removed and photographed as well. Cornell University Vet School has some great photos of what to look for in Mareks. You may see a spotty liver, tiny lesions on intestines, spleen, heart, and other organs. The sciatic nerves may be enlarged in one leg. Not that many have ocular Mareks, but that can be a sign. Be sure to check out this link and look at the pictures of clinical signs as well as gross lesions:
https://partnersah.vet.cornell.edu/avian-atlas/#/disease/Marek's_Disease

There is a good necropsy video here where organs are labeled:

 

[azygous]

Chickens develop resistance after being exposed to the viruses. It's more likely to happen with avian leucosis than Marek's, and each virus has a number of strains. Of course you can always learn a lot by doing your own necropsy, and as @Eggcessive says, you'll have a lot of help here interpreting what you find.

 

[Sussex19]

Sorry I haven't relied sooner, I've had cold and been feeling a bit fuzzy headed.

Can you post a picture of your chicken’s eye here?

Here is one from a couple of weeks ago, I don't think it has changed much.
I can get newer one if its wanted.

Thank you for the links, I'll study them soon.
I'll get photos of things, and let you know how it goes.

 

[Eggcessive]

The picture of the eye is pretty much evidence of the ocular form of Mareks disease. Some chickens can have just the ocular form, and no other types of symptoms. Mareks disease includes ocular, cutaneous (skin form,) neural (nerve paralysis,) and tumors in the body. The picture below shows a noramal eye in the middle, while the one on the left and right show an irregular pupil and graying of the iris. It usually ends up more gray than those pictures eventually.

 

[Sussex19]

The picture of the eye is pretty much evidence of the ocular form of Mareks disease. Some chickens can have just the ocular form, and no other types of symptoms. Mareks disease includes ocular, cutaneous (skin form,) neural (nerve paralysis,) and tumors in the body.

So you think its pretty conclusive?
I just can't think why more aren't showing some kind of symptoms...
I got them from I think 6 different places, so you wouldn't think they would all have immunity to the same strain.
I am puzzled!

 

[coach723]

There are different strains of Marek's, some are much more virulent than others. That combined with varying immune systems means that not all birds will neccesarily show symptoms, not all birds will neccesarily die. If you have a milder strain, then you may only have sporadic cases of symptoms. With more virulent strains it can have a much higher mortality, sometimes taking out most of a flock. Some birds may be naturally more resistant due to individual genetics and immune systems. It's very hard to predict.