Wednesday, November 9, 2016

Chicken breeds most and least susceptible to Marek's

Marek's is a chicken disease that can cause paralysis, tumors, immunosuppression, and death.  I recently put a sick hen down and had a necropsy performed.  The result? Cocci, but underlying cause of death was Marek's.  

Mareks can live for several years in the environment.  Once you have it, you have to assume all your hens have it and are shedding the virus through dander and feathers.  There is a vaccine for it, but it doesn't prevent the spread of Marek's, just the growth of tumors.

I am not allowed to have a rooster, so I can't breed my own immune flock.  The best I can do is buy chicks from breeds that aren't as susceptible, although it varies by individual.  

I haven't decided if I want to buy vaccinated chicks.  I may try just getting unvaccinated chicks.  The strain of Marek's only affected 1 of my hens, so it isn't one of the more virulent ones. Once I vaccinate, all will have to be vaccinated.

From what I've found online, here are breeds that are most and least susceptible:

Most susceptible 

Most immune / least susceptible 
Egyptian fayoumi 
White leghorn*
Campine? (Supposedly descended from the fayoumi so maybe)

*certain bloodlines.  Things I read said leghorn were less susceptible than rode island reds


Sunday, November 6, 2016

Dealing with Marek's

Marek's is a horrible and annoying disease.  Traditional Marek's causes paralysis, tumors, and lesions, but there are different strains, some with different symptoms and mortality rates.  Once you have it, not only do you loose a number of chickens, but you must accept that 1) your surviving hens are carriers and 2) you have the virus in your soil where it can live for months, sometimes years.

I recently had to put down an eighteen-month-old hen.  She had diarrhea and wasn't eating.  I separated her and treated her for coccidiosis, a disease that causes green diarrhea, but she didn't get better.  After a week and a half, I put her down and took her to the Utah State University Veterinary diagnostic clinic.  They quickly called me back and told me cocci, a very bad case.  I felt bad and was surprised the Corid didn't treat it since I had done everything correctly.  When I got the written report a week later, it had a second diagnosis.  Cocci killed her, but she had Marek's as well, contributing to her death.  Some forms of Marek's suppress the immune system making hens very vulnerable to cocci.  She hadn't been vaccinated since I hatched her myself.

I felt some relief, putting her down had been the right choice, but now what?  Did I have to put down my other hens too?  After reading on-line, I came to the conclusion that it wouldn't help all that much.  They were acting fine, so were probably resistant, but I had to consider them carriers.  This meant I couldn't sell them next year as I had planned.  Any chicken I brought on to my property could not leave.  I would need to process them or allow them to die natural deaths.

I'm still dealing with what to do about new chicks.  Here are some of my thoughts:

  1. All chicks I buy need to be vaccinated. They also have to be kept away from my older chickens for at least two weeks for the vaccine to make them resistant.  This also means I can't use a broody to raise them.
  2. I cannot get silkies like I had planned.  Bantam chicks can't be vaccinated.  Also, Silkies are very susceptible to Marek's
  3. I could try hatching chicks from resistant lines.  Marek's is not spread through the egg.  There is a petting zoo / farm near us that sells hatching eggs.  I could get eggs from there because I'm pretty sure those chickens are exposed to all kinds of stuff, and if they're still alive then they must have some resistance.
  4. I had put some of the used bedding in my garden to use as compost.  I will remove as much as I can and not do that anymore to prevent build up of pathogens.
  5. In the spring, I will clean out the coop thoroughly with oxine or vikron-s before I get new chicks and again before I add the new hens in.  Bleach is not effective against Marek's.
  6. I'm wondering about putting down cement pavers in the run so it would be easier to clean and disinfect.
Fortunately, I have all winter to figure out what to do.