Something was very wrong with Marissa the Cream Legbar hen. Her belly was blown up like an over-inflated basketball and she had lost interest in the usual chicken business of scratching and pecking her way around the run with the rest of the flock. Instead, she would find a quiet corner and just stand there all day, looking sad. This three-year-old hen has, for the most part, lived the happy and uneventful Hipster Hen life since the day she hatched – until last winter’s polar vortex. Several chicken’s combs became frostbitten in that extreme cold, and Marissa had the worst case, no doubt due to a combination of her low rank in the flock which kept her further from the heat panels, and her bad luck in having a large comb. While the black scabs eventually fell off and her comb eventually healed, Marissa just didn’t seem to be the same old Marissa. Her egg laying tailed off and by mid-summer she had landed in the place I described: Lethargy and a huge, swollen abdomen.

There are a number of diseases that can cause a hen’s abdomen to swell and none of them are good. In fact, I knew that most of those diseases were ultimately fatal, and the only reasons to work through a differential diagnosis was to determine how long Marissa had left to live and to see if there was anything I could do to reduce her discomfort and improve her quality of life in her remaining time. I consulted my usual books and on-line resources and came up with this list of possible afflictions.

Chicken Diseases that Cause a Swollen Abdomen

Salpingitis/Egg Peritonitis

Nature provided chickens with only one hole (it’s called a vent or cloaca) and everything entering the world from the chicken enters through the same hole. Fortunately, eggs and bodily waste don’t mix due to muscles at the base of the oviduct that keeps it separated from the cloaca except when an egg is passing through. As a hen ages these muscle can become slack, increasing the likelihood for poop to back up into the oviduct and cause an infection. Salpingitis is the medical term for oviduct infection, and it is bad news. An infected oviduct can fill up with pus mixed with all the components that normally would develop into eggs, including membranes, yolk, and bits of shell. This material can pass out of the hen, resulting in the appearance in the nest box of a smelly, disgusting object colloquially referred to as a “lash egg”. This gunk can also build up to a point that it breaks through the oviduct lining and gets into the hen’s abdominal (peritoneal) cavity where it creates a raging infection—a condition known as egg peritonitis. That’s when you’ll notice that your hen’s abdomen is swollen and that she’s standing and walking with her back-end low to the floor because of the discomfort and the additional weight of the accumulating fluid. Peritonitis is very painful, there are really no good treatment options and it is usually quickly fatal.

Egg binding

Sometimes fully formed eggs get stuck at the end of a hen’s oviduct right where it empties into the cloaca. This can occur for a number of reasons, including the formation extremely large egg, or a hen’s inability to push the egg out due to illness or obesity. Once an egg becomes stuck it forms a traffic jam as other eggs line up behind it. Eventually the hen’s abdomen becomes swollen from unpassed eggs and as her center of gravity shifts, she develops a characteristic upright “penguin walk.” If the hen can’t manage to pass the egg causing the blockage, she will die.

Ovarian cysts

Unlike most animals, hens only use one of their ovaries – the left one. It is fairly common for the right, undeveloped ovary to form a fluid-filled cyst. Most of the time this right ovarian cyst doesn’t grow beyond an inch in size, but sometimes it can grow much larger, and it sometimes can become so large that it fills the entire abdominal cavity. While a hen can live her entire life with a small cyst, if the cyst enlarges to the point that it is exerting constant pressure on the internal organs, it can be fatal.

Extreme obesity

Sometimes those low-hanging tummies on our hens are just fat. Backyard chickens, after all, are often our pets. And sometimes we give our pets way too many treats. Fatty liver syndrome is common cause of death in obese hens. The liver becomes enlarged, mushy, and can eventually rupture and bleed, causing immediate death.

Tumors

There are a handful of viral diseases that cause tumor formation in chickens. Marek’s disease is the most well known and the most common (see my post on Marek’s Disease here). How common is this disease? The Merck Veterinary Manual states that “every flock, except for those maintained under strict pathogen-free conditions, is presumed to be infected.” If your chickens have been vaccinated or are really lucky, they may have no symptoms even though they’re carrying the virus. Symptoms are incredibly variable and dependent upon where tumors form. If tumors form in the liver, kidneys, or ovaries, abdominal swelling can occur. As the tumors enlarge, the chicken becomes lethargic, stops eating, loses weight, and ultimately dies.

Ascites (Water belly)

Ascites is a bit confusing, because unlike the other conditions listed here, it is not a disease per se, but a condition. “Ascites” simply means that a chicken is accumulating lots of abdominal fluid due to any number of causes. Here are the main ones:

Heart failure: If a chicken’s body needs more oxygen than its heart and lungs can provide, the heart works harder to pump more blood. If this happens continuously, the heart muscles enlarge and can become so thick that the heart valves can no longer close. Then blood backs up and pools in the liver. The increased pressure in the liver caused by the pooling blood causes the liver to leak fluid, which drains to the lowest possible point in the chicken—the abdominal cavity, where it just sits and continues to build up. This is a common occurrence in meat chickens that have been bred to gain weight in an unhealthy and abnormally rapid fashion. It is not so common in laying hens.
Oxygen deprivation: Chickens may be oxygen deprived due to lung infections, high altitudes, excessive dust in the coop, coop ammonia build-up due to poor sanitation, poor ventilation, obesity causing clogged arteries, or simply bad genetics. When chickens can’t get enough air on a regular basis, the same cascade I outlined for heart failure initiates and the end result is the same—an abdominal cavity filled with fluid.
Ovarian cancer: Laying an egg almost every single day takes its toll on hens in a number of ways. For one thing, high ovulation rates result in high rates of ovarian cancer in hens. Over 30% of hens develop ovarian cancer after two and a half years-of-age. The hard tumor surface can cause abdominal irritation which can result in fluid leakage and buildup.

Marissa’s Differential Diagnosis

The very fact that Marissa had been suffering all summer indicated to me that she didn’t have an internal infection. It would have made her much sicker much faster, and she simply would not have survived. So, I ruled out egg peritonitis based on the fact that she was still living. I’ve had egg bound hens before and Marissa’s condition didn’t look like that. She was not penguin walking and I couldn’t feel any obvious hard lumps. The absence of hard lumps also allowed me to rule out any obvious large tumors. And she simply was not fat. Except for her large squishy abdomen, she looked like a normal hen. But that abdomen was very large, and so very squishy! I was going with ascites. And I was going to the vet!

Sometimes when my hens get sick, it’s pretty obvious what’s going on and I’m able to initiate treatment myself without a vet visit. Other times, a seemingly healthy hen goes rapidly downhill and dies in a matter of hours or days. Hens are prey animals thus do their best to mask their illness until the very end. In these cases, a trip to the vet is pointless. But Marissa was potentially afflicted with a chronic condition, and there were a few treatment options – not necessarily to cure this little hen, but definitely to ease her discomfort and improve her quality of life. So, I felt a trip to the vet was well worthwhile.

A Visit to the Local Friendly Vet

In early October, I put Marissa in a pet carrier and made the drive to the only vet in my area that deals with chickens. I gave Dr. B Marissa’s history and he performed a quick exam. He quickly concluded that she had ascites. I was happy to have a diagnosis, and doubly happy that he confirmed that I had been on the right track.

Then Dr. B performed a paracentesis to get rid of the overabundance of fluid in Marissa’s abdominal cavity—simply a matter of inserting a needle into her abdomen and drawing off the fluid. He removed about 500 ml of fluid; over a pint! There was certainly a lot more than 500 ml of excess fluid in Marissa, but removing too much fluid all at once can cause a chicken to go into shock and can be fatal. But removing a pint made Marissa look a bit less like an over-inflated basketball, and I’m sure she felt a lot more comfortable. The fluid was thin, colorless, and almost clear, a confirmation that Marissa was not suffering from egg peritonitis, which would produce a thick, pus-like material. Dr. B explained that fluid originating in the liver should have a yellow cast, so he felt that Marissa was afflicted with an ovarian tumor.

Then Dr. B inserted a small hormone implant in Marissa’s breast muscle – a treatment that was completely new and surprising to me. Deslorelin is a hormone implant that is approved as a contraceptive for ferrets and dogs. It has been used off-label to stop birds from laying eggs, and recent research has also shown it to be effective in suppressing reproductive disorders in birds. I put Marissa back into her pet carrier and took her home knowing that she had been given the best treatment available for one little hen with ascites and an ovarian tumor.

She spent the first few days after her visit to the vet in the chicken-rehab unit—a crate that I’d parked right next to the coop fence. Marissa’s two best friends, Paulette and Nicky, spent most of their time on the other side of the fence keeping her company, a phenomenon I’ve seen time and time again when hens are sick. Chickens care about their friends.

Marissa, pre-illness (l), with her best friends, Nicky (m), and Paulette (r)

Paracentesis

I didn’t see much improvement in Marissa. There was no guarantee that the Deslorelin was going to work and even if it did, it could take a couple weeks to take effect. Meanwhile, Marissa was obviously filling up with more fluid. She clearly needed to have some fluid drained again and I decided that this time I would do it myself. This is something you can do at home—with this huge caveat: You have to know what you’re doing. If you blunder into it blindly and ignorantly, you could cause serious harm to your hen that could even result in her death. Here are some suggestions and things to consider before performing paracentesis on your hen:

Work in a clean area. “Operating room sterile” is obviously not practical or achievable, but how about your basement or a nice clean outdoor area? Your coop and run are not clean - where there are chickens there is lurking chicken poop.
Be diligent in finding a good spot for the needle insertion. You need to work low on the chicken’s abdomen, and to the right of her cloaca. There are organs in that abdomen and you don’t want to puncture them!
Clean the area before inserting the needle and if feathers are in the way, clip them. I suggest cleaning first with alcohol, then with a disinfectant like betadine, then with alcohol again. You will be inserting a needle into a sterile body site and if you introduce bacteria with the needle you can create a raging infection.
Hold the hen under your arm like a football, with her tail facing out. This can be a one-person procedure, but it’s a whole lot easier if you have one person to hold and one to do the procedure.
If the bore of your needle is too small it will take you forever to draw any amount of fluid out. If the bore of the needle is too large, the puncture may take a long time to heal and fluid may continue to dribble from the puncture site. If too much fluid is removed or dribbles out in a short period of time, the hen could go into shock. I suggest an 18-gauge needle as the “just right” size.
Use a large syringe – as large as you can deftly handle. Even with the largest syringe you can manage, you will be filling it several times. Do NOT puncture your hen more than once! When the syringe is full, separate it from the needle at the hub and leave the needle in place in the hen while you empty the syringe. Alternatively, instead of a syringe, I inserted a needle that was fitted to catheter tubing. There was sufficient pressure in the hen’s abdominal cavity to force the fluid through the tubing and into a waste container. I put graduated markings on my waste container beforehand so I knew exactly how much fluid I was extracting. When I was done I simply removed the needle.
It’s a good idea see how this procedure is done before attempting it yourself, and fortunately, there are a bunch of on-line demonstration videos. Unfortunately, there is quite a range in quality – all the way down to somebody using a tiny syringe that they stab into their poor hen multiple times! The video that, in my opinion, is head and shoulders above all the rest was performed and posted by Teresa Johnson. Teresa obviously cares about her little hen and displays the professional calm and competence of somebody who has done this more than a few times before thus know exactly what she’s doing. With Teresa’s permission, I’ve embedded her video here:

Healing

I removed another pint of fluid and Marissa actually started perking up the next day! She’s been back in the coop with the other hens about a month now. She’s gone into an amazing full-fledged molt, probably partially because of the hormonal changes caused by the Deslorelin, but also probably just because it’s that time of year. So, she looks pretty bad – she’s got the shabby look that hens get when they molt. But she feels great! I can tell by the way she’s acting—she’s making the rounds in the chicken run with her friends every day. She’s actively pecking, scratching, and doing all those other normal chicken activities. She’s eating well. And her abdomen has shrunk down to the size of a normal chicken tummy—the Deslorelin is doing its thing! Right now, life is good for Marissa; better than it’s been for nearly a year. I have no delusions that her remission will last forever. Without a doubt, when the hormone wears off in eight or ten months, the tumors will reassert themselves, her belly will swell up and I’ll be forced to decide what happens next. But in the meantime, this sweet girl is getting a second chance to enjoy life as fully as any chicken can.