Monthly Archives: March 2021

Help Your Flock Spring Forward

Spring is springing in Ontario, where I live! I’m sad that skiing is dying, but I saw the maintenance committee at the local golf course starting work, so there is hope! (Plus, I bought a new (used) set of irons over the winter, so my golf excuses are all set for this season! I am also seeing chickens out and about, and “Eggs for Sale” signs getting dusted off and hung.

Probably my last day on the slopes 😦

Spring is an important time for backyard flocks. Weather is variable, runs are muddy, and chickens are starting to lay…..hard. Wet environments cause more stress on your flocks from things like coccidiosis and worms, who will be sporulating and hatching, respectively. Managing the change of season will help set up your summer to be hassle free and keep your chickens comfortable and healthy.

Spring is the season of bumblefoot, egg binding and impacted crops. Wet feet and dirty perches are the main risk factors for bumblefoot. Think of soaking in a bathtub for hours (or getting a flooded rubber boot first thing in the morning). Your skin gets swollen, and more porous, and eventually sore. Now, if you are a chicken with wet litter or wet runs, you settle in to sleep, with your feet locked around a perch….now small wounds occur and bacteria get in, resulting in very painful infections that often require minor surgery to fix the lameness that occurs. Preventing bumblefoot requires good drainage, and coop cleaning, and spring is the most crucial time for this.

Long-time pressure on wet/dirty feet predispose bumblefoot

Egg laying chickens need way more calcium than do non-laying birds. Your hens likely took a winter holiday, but are now coming back into lay with a vengeance as the daylength increases. Since Calcium is laid down on the shell overnight, and lay occurs in the morning, we are asking hens to expend a massive amount of physical effort when their blood calcium levels are at their lowest. Calcium is also crucial for muscle contraction. If you are on a marginal (or deficient) amount of calcium in your feed, you may not know it, since the hens were not laying regularly. But in the spring, you may well end up with a hen that forms a shelled egg, but doesn’t have the strength to push it out. If this happens, giving extra sources of calcium in the form of limestone chips, oyster shell or clean eggshells will help. Dissolving a Tums antacid in water and dosing the affected chicken can help as a treatment. If the egg doesn’t pass in the first 24 hours or so, this becomes a bit of an emergency, since the membranes inside the vent can stick to the shell and make it less and less likely that the egg will pass naturally. Using lube to help the egg come out, and eventually it may be necessary to break the shell internally and remove the egg in pieces. Please contact your vet early if you have an egg-bound hen, since the later we see the bird, the harder it is to help her.

Severe case of bumblefoot. This is very painful, and often needs surgical intervention to help it heal

The other thing to be watchful in the spring ins air quality in the coop. When the day is warm and wet, and the nights get cold, often the first response is to close up the coop to keep it warm. The problem with this is that wet litter (and wet feet….see above) increases the amount of ammonia produced through bacterial respiration. This can cause irritation to the respiratory tract, the eyes and the bird’s feet. Resist the urge to close up your coop….temperature should never trump air quality. Chickens can handle quite cold temperatures, as long as the humidity doesn’t get high.

Enjoy your spring, and eat lots of omelets….you should have plenty of raw materials!!!


Mareks Vaccine Info

As I talk to different backyard producers, and offer vaccines to keepers in my area, the number one issue that causes consternation and confusion is Mareks vaccination. Opinions range from “don’t vaccinate, it will make your birds sick”, to “vaccinated birds pose a risk to non-vaccinated birds”, to “vaccines result in hotter strains of Mareks Disease in the field”, to “don’t vaccinate, just breed for resistance”. When I try to discuss these opinions with the people who promote them, I get half-truths, misunderstandings and different philosophies on health provision. So, to decrease the number of times I explain my point of view on Mareks vaccine, here is a summary of what I know, and how I think the vaccine works. Keep in mind, I have looked after roughly 100 million vaccinated birds that have ALL been housed in places where large numbers of birds have been kept before, and have almost definitely all been exposed to Mareks Disease.

Vaccines work by exposing an animal’s immune system either to a weakened form of a disease causing agent, or a protein that mimics one that is produced by a disease causing agent, thereby tricking the immune system into attacking the agent the first time the body actually sees it. Every foreign protein that enters the body is separated and presented to the immune system by cells called macrophages. It is important to note first off that Mareks Vaccine CANNOT cause Mareks Disease, and CANNOT shed the vaccine to cause disease in other birds in the flock. Unfortunately, not sharing the virus with flockmates means that only the chicks that have been injected will have any immunity to Mareks.

Antibodies that are effective against a virus must be very specific. The common analogy is a lock and key relationship. Creating a key to fit a lock takes a long time, and a bunch of energy, but cutting identical keys is quick and easy. The proteins presented by macrophages are the templates for key production. Once the first key is produced, it is stored in the body for reference (called immunoglobulin M or IgM). If that same protein enters the body, IgM is used as a template to make tons of immunoglobulin G, which meet up with the protein, and cause it to be killed. (I hope you appreciate that entire text books are written on Immune function, and immune stimulation. This is a Cole’s notes version of a Cole’s notes version of immunology).

So, since this process is so INCREDIBLY simple, why the confusion and disagreement on Mareks vaccines? Well, unfortunately, with MD immunology, there is a wrinkle. The IgG that is produced by the body does not kill ALL the Mareks virus that enters the body. Much of the virus dies, and the amount that is available to be shed is very much decreased, but the IgG merely surrounds some of the virus particles, and keeps them from entering the cells of the vaccinated chicken, saving it from disease, but not preventing the bird from carrying the virus, and potentially shedding it. This is why the vaccine is described as “leaky”. Even vaccinated birds can harbour Mareks Disease Virus, if they are exposed to it. Most people have read this somewhere, and form strong opinions around it. Here is what many people DON’T know. The vaccine reduces the amount of virus shed to about 1/1000 to 1/10000 the amount that is shed in non-vaccinated birds. A study by Nair, et al. in 2010 found the following. 9/9 birds who got challenged with MD with no vaccine died. 0/9 birds with one vaccine, and 1/9 birds with another vaccine died. But the authors also measured the shedding rate of vaccinated and non-vaccinated birds:

Triangles are Unvaccinated. Squares are Vaccinated birds.

What I want to point out is the scale. The non-vaccinated chickens shed around to 1 million virus particles per thousand cells while vaccinated birds shed less than 10% as much virus. So the leakiness of the vaccine is less than 10% that of unvaccinated birds. Even though Mareks can be carried and shed by vaccinated birds, the risk is reduced to less than 10% of the non-vaccinated birds….assuming the non-vaccinated birds survive.

In a way, that is probably the greatest risk posed by vaccinated chickens with respect to shedding Mareks Disease….they don’t die as young, so they survive long enough to be a source of virus longer. The problem is, most backyarders will replace the birds that die, and if the replacements are non-vaccinated as well, they harbour and shed vast amounts of the virus they pick up when they join the infected flock.

As for vaccines increasing the rate of mutation and the increase in virulence of Mareks disease viruses present, that is probably true. Anything that makes it harder for any biological being to survive will add pressure to evolve to be more successful. It’s why cheetahs run so fast….the slow ones died out during hard times. (Interestingly, the 3rd and 4th fastest animals on earth are the springbok and wildebeest, 2 of the cheetah’s main prey). But, when you consider the risk of a virulent virus developing in backyard flocks when compared to the evolutionary pressure of literally billions of vaccinated commercial chickens yearly, I think the risk is put into perspective. The odds of having to protect your flock from a virulent strain from somewhere else is astronomically higher than the risk of developing a highly pathogenic strain in your flock.

Finally, the arguement for selecting robust breeds of chickens that are naturally resistant to Mareks, rather than vaccinating. As a vet, I see that as an arguement to let any weak ones die. There is no way to predict what birds will succumb to Mareks. Often it takes well over a year for the tumors to cause symptoms in a chicken. So, is the answer to keep your chickens until they are 2-3 years old before hatching any chicks? By then, you may only have 10% survivability. You need 90% of your chickens to die a preventable death before you can even begin to select for resistance. If that was it, it might be doable. The problem is that the next generation is only slightly more resistant to Mareks than the current one. You have to sacrifices birds for generations to get a noticeable increase in resistance. And then hope the virus doesn’t mutate, and wipe out all your gains. Believe me, all the genetic companies are very interested in increasing genetic resistance to Mareks Disease, but they haven’t made significant progress.

So….there are my views on Mareks Vaccines. There are 2 types of chickens….those that have been vaccinated for Mareks Disease, or those that should have been vaccinated for Mareks Disease. I expect some of you will disagree, and I welcome any questions….I will answer them as clearly as I can.

Oh, and my experience with Mareks Disease in the 100+ Million vaccinated birds I have dealt with? I carry my phone with me, and take pictures whenever I find a bird with tumors….it’s rare enough that it is an event for me to find a bird full of tumors. Make of that what you will.

Mike the Chicken Vet

Mike The Chicken Vet V2.0

Hi Everyone!

Contrary to rumors (and certain people’s hopes, I’m sure!), I have not disappeared, died or been abducted by aliens. I have been busy working my job as a commercial laying hen vet, being surprisingly busy with poultry welfare projects, changing lifestyle (amicable divorce, dating, now re-engaged), raising kids, etc, etc. I know, nobody cares about that stuff. The other thing that many of you MIGHT care about is that I have started a relationship (not part of the dating fiasco…..professional relationship) with a staggeringly competent vet who has built a career doing small animal, exotic, and avian medicine. We bumped into each other on the opposite sides of an animal welfare investigation of a backyard flock. Neither one of us needed to be “right”, and worked together to solve the problems, help the owner and get the birds into a better situation.

Giving ILT vaccine via eyedrop to a Polish pullet

After the investigation, Nickey was telling me about HER backyard flock, and the lack of information readily available for backyard poultry, and the impossibility of getting/providing vaccines for small groups of birds. One thing led to another, and we got talking about both our opportunities, abilities and knowledge. She was competent and confident in all the aspects of individual bird care….surgeries, diagnostics, work-ups and hospitalization. I know disease transmission, vaccines, biosecurity, behaviour, nutrition and post-mortem examination. My new fiance made me watch some romantic movie and somebody said “you complete me….” as sappy music played (I might not have been watching closely). It was sort of like that with Nickey.

Oral vaccines for a chick

So….long story short, we have found a way to provide vaccines, advice and medicine to backyard flocks. With all this exposure to small flocks, I am facing a TON of questions about backyard chickens that I am actually surprised are not more easy to answer. So, I thought I would resuscitate the blog with a bit of a new focus on backyard hens. I will still try to explain and expose what commercial farms are like, and may rant about other things occasionally, but will use this as a space to try to explain some of the misconceptions out there about backyard flocks.

Hope you guys come along for the ride.

Mike the Chicken Vet