Blood on Eggshell – Should you worry?
Our chicken eggs come in wide varieties, shapes, and textures. Abnormal eggs aren't that uncommon. Once your hens are old enough to start laying, chances are, during their lifetime, they'll lay some abnormal-looking eggs. But when blood is involved, it's best to be alert and watch your hen.
Should you worry when you find blood on an eggshell? Let's address the most common reasons your chicken eggs have blood on the outside.
How an egg is formed
Before getting into the details of things that can go wrong during the egg-laying process, we need to know how an egg is formed inside the hen's body. A few things happen inside your chicken before she lays a fresh egg.
- The ovary releases a yolk as soon as it reaches the correct size. This happens, depending on breed to breed, daily or a couple of times a week. This process is called ovulation.
- Once the yolk is released, it starts its journey through the hens' reproductive system, starting in the infundibulum.
- The next stop is the magnum. This is where the albumen is added.
- As soon as the albumen is added, the yolk and albumen pass to the isthmus, where shell membranes are added. An egg exists of two shell membranes, an inside and outside membrane.
- At last, the eggshell is formed. This takes up the most time and happens in the shell gland. The shell gland is also the place where shell pigments create the egg color.
- Once the shell is formed, the egg resumes its journey. Just before reaching the cloaca, where the egg gets pushed out, the egg turns large end first.
Blood on the eggshell
Now we know how an egg forms inside a chicken's body, we can try and figure out what causes smears of blood on the outside of the egg. We'll address a couple of issues:
- Internal tear or injury
- Vent is not stretched enough
- Large egg
- Prolapsed vent
Internal tear or injury
A common cause of a blood smear on the eggshell is a minor injury inside the chickens' vent area. This can be caused by a broken blood vessel as the egg chute is lined with blood vessels, making it not uncommon to break one occasionally. If your chicken seems fine, and there is no visible outside damage or blood around the vent area, she'll be fine. But keep a closer eye on your hens for the first few days and check the eggs for bloody spots.
Vent is not stretched enough
A pullet that just started laying can occasionally lay eggs with some blood spots. It's nothing to be concerned about, as long as she seems healthy. The vent area must be stretched out for the eggs to come out without damaging the egg chute. This will happen naturally after a couple of weeks, but in the meantime, a blood vessel can burst when the egg is pushed out.
Chickens lay various eggs, even double and triple yolkers! Or more. According to Guinness World Records, the world record for the highest number of yolks found in an egg is nine (9!). More egg yolks mean larger eggs. So, large eggs can cause a bit of damage like a torn blood vessel or minor injury because the vent area is not used to this egg size. Your hen will recover by herself; there is no need to be concerned.
A significant issue, most common in young or older hens, is a prolapsed vent which can cause bloody spots on eggshells. This is a life-threatening situation where your chicken has to be treated as soon as possible. Luckily, it's very easy to spot a prolapsed vent in chickens. So you can act immediately and start treatment or take your chicken to a vet.
Prolapsed vent is a condition where the reproductive tract tissue does not retract inside the chicken's body after an egg has been laid. Due to the bare tissue sticking out of the chicken's bum, bloody eggshells are possible. You first need to separate her from the flock, so other chickens can't peck the bare tissue. Next, stop feeding the hen pellet feed, switch to mixed corn instead, and place her in a dark environment. This way, egg production will slow down, which gives the area time to heal. Contact a veterinarian, or, in case you don't have a vet that specializes in poultry, try to handle the problem yourself.
If the prolapsed vent is small in size, meaning smaller than a ping-pong ball, the issue may resolve on its own. If your chicken has a dirty bum, soak her in lukewarm water to clean the vent area. Don't try and remove dried poo from the feathers; you can damage the tissue. After a couple of days, the prolapsed vent should be resolved. Keep a close eye on her so that the problem does not worsen.
When the prolapsed vent is bigger than a ping pong ball and no vet is available, try to reinsert the tissue by gently pushing it back inside. Wear protective gloves and use a lubricant so you won't damage any tissue. Hold the tissue in its place for a couple of minutes so it won't come back out.
Introduce her back to the flock once she's completely healed.
When should you worry?
Most reasons for bloody smears on eggshells are pretty innocent. Unless you notice your chicken has a prolapsed vent, which is very easily recognizable, there's no need to worry immediately. But when you say 'blood' you say 'injury'. So, always be extra attentive when noticing one of the following issues:
- Lethargic chicken
- Blood in chicken poop
- Frequent bloody eggshells
- Bare bottom or dirty bottom
Always consult a veterinarian if you aren't sure of the current situation of your chicken.
Let's sum up
Bloody eggshells are quite common in young hens and aren't always a big issue. Mainly, the blood is caused by a minor injury inside the egg chute or a burst in a blood vessel. If your chicken seems happy and healthy, keep an eye on her, but she'll be ok.
A prolapsed vent can be a reason for blood on the eggshell. It's easily recognizable by the bare tissue sticking out of the chicken's bum. This situation is life-threatening and should be dealt with immediately. Next to these issues, keep an eye out for bloody chicken poop, dirty vent areas, lethargic chickens, or if your hen frequently lays bloody eggs.
If you want to read more about chicken health problems, symptoms, and diseases, check out our 'Health Page'. You'll find a 'Symptom Checker', a complete list of 'Chicken Behavior', and an overlook of the most common 'Chicken Diseases'. Or go to 'The Classroom' and find a comprehensive list of all Chicken Fans articles.