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This is a unique disease case, may be used as a discussion material for the avian vet and veterinary students.

I often get cases of lameness (paralysis) in pullet (layer brown) chicken in the field. This case is only common in certain age ranges. Around the age of 9 to 16 weeks. The peak incidence of lameness chickens occurs at the age of 12 to 14 weeks. The observed symptoms are, the chickens are inactive, lazy to walk, walk very slowly, chicken feathers look dull, thin/skinny, lameness/paralyzed, chickens with symptoms like these found in almost every pen, and also in another house in the same flock. And followed by death.

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Lameness in brown chicken. Avian vet

Often at the age of 9 weeks, it appears that only a few chickens look lethargic, inactive, walking slowly, found on each pen at the same time. Also in another house. There are no respiratory symptoms or symptoms of gastrointestinal disease. A few weeks later there are many chickens that show such symptoms. the death rate began to rise.

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Lameness in pullet. avian vet

Chickens look hard to walk cause they do not get enough food and drinks. Chicken becomes thin, lack of nutritional intake, and dehydration. There were no symptoms of the other diseases that had been observed in these chickens before. Everything goes well until this chicken reaches the age of 9 weeks. The performance of body weight is quite good before.

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The spread of Disease. avian vet

The spread of the disease seems to occur simultaneously in every pen and every chicken houses. The pattern of spread of this disease is very different from other disease patterns such as Newcastle disease, IB or avian influenza, coryza etc.

In other infectious diseases, the disease starts from a spot in a house first, from a few chickens first. Then it will be observed a pattern of spreading the disease to another chicken that is located close to a sick chicken. Then it will take time for the occurrence of the same disease in other houses.

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Peak incidence & mortality at 12-14 weeks. Avian vet

The incidence rate of this disease will drop without any treatment after chicken over 18 weeks. But some breeders give antibiotics to their chicken flock. Some of them also provide nutrients with high calcium in the feed. However, many breeders do not do any treatment for their chickens, except for culling of sick chickens. Other chickens are still healthy.

Only certain chickens suffer from the disease. Not observed the spread of disease to other chickens. If a farmer has 5000 chickens in a house, there are only 10-500 (1-10%) of chickens suffering from the disease. Clinical symptoms will be observed starting at week 9, and peak at week 13. This disease occurs only in certain chickens, there is no spread of disease in other chickens.

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avian vet. FHN in chicken (green arrow: normal femoral head . Yellow: Degenerative changes, necrosis in the hip bone-FHN )

Severe pathologic lesions, femoral head necrosis, severe inflammation of the bone joints, especially of the femoral bone. It affects the mobility of the birds and is usually related with pain. Lameness will cause birds to suffer and limit their natural movements, likely resulting in reduced feed and water intake.

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Avian vet. Femoral head necrosis, yellow arrow: progressive loss of the subchondral bone, arthritis, and osteomyelitis, unilateral or bilateral.

Necrotic degeneration and microbial infection primarily within the proximal heads of the femur.

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Bacterial chondronecrosis with osteomyelitis. Avian Vet

Many breeders assume this is a problem of lack of mineral or calcium intake. So that the femur bones easy to break. Though the incidence of this disease occurs only in some chickens. If the chicken feed lacks calcium, then the incidence rate should be very high. So, many breeders who make nutritional changes to feed by adding calcium and vitamin D do not provide effective results.

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femoral bone fracture observed, chondronecrosis. epiphyseal breakage, Avian vet

This is due to bacterial infection. I get Staphylococcus and  E Coli in this case. Indeed, bacteria cause necrosis of the femoral head. But where did the bacteria come from?

Staphylococcus and E Coli are common bacteria found in farms and chicken houses floor.

see also: Pictures of Parasitic Diseases in Poultry

If the common staphylococci bacteria in the farm becomes the main problem, why do the bacteria infect only a few chickens? Why do clinical symptoms begin to appear at 9 weeks? Why do the bacteria not cause the same disease in chickens over the age of 20 weeks?

It’s a question that still puzzles me. If the chickens are infected by the bacteria that come from the farm itself, then the incidence of this disease should not appear simultaneously in every house. And should the disease appear in any age range.

If the bacteria come from the floor of the house, but I do not find any cuts on the chicken’s foot, as the entrance of the bacteria. There is no necrosis in the leg muscle tissue. There were no significant lesions in the joints of the metatarsal and tibia bones that lie closer to the chicken’s foot.

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Lameness, resulting in reduced feed and water intake & death. Avian vet

Some farmers consider the contamination of syringes while vaccinating. But this assumption is not proven. There should be necrosis of the leg muscles due to a syringe that has been contaminated with bacteria. But in reality, the chicken leg muscles are not problematic. The problem is only in the joints of the femur bone.

see also: Pictures of Bacterial Diseases in Poultry

I do not isolate mycoplasma for this case, but this chicken flock has no respiratory problems before.

Staphylococci and e coli are the cause of necrosis in the femur bone, but how does this happen in only a few percent of chickens? How these bacteria can damage the femur joint without causing severe lesions in other organs., These are the questions. And why cases always have the same pattern, starting at 9 weeks and peaking at week 13?.

I assume this is not just a matter of bacterial infection. There are certain reasons that cause why certain chickens can be infected by this bacteria.
Probably immunosuppressive. From thousands of chicks, there are several chickens suffering from immunosuppressive. These chickens will have problems with bacterial infections. But why does infection occur only in bone joints by Staphylococcus & e coli, why are these chickens not susceptible to other diseases, such as respiratory and digestive cases?

My assumption is also not exactly right yet. But I got a very significant seropositive to chicken anemia virus, but these chickens never vaccinated against CAV before. But I can not confirm and justify a diagnosis because of the lack of laboratory facilities.

But I am very sure, that this is not just a matter of bacterial infection, there must be other reasons so that these bacteria can reach the femur joints.

Perhaps this problem starts from the contamination of contamination from hatchery or farm parent stock. Of the thousands of chicks or day old chickens who come to commercial farms, there are some chicks that carry the problem, and at the age of 9 weeks, clinical symptoms will be seen. It may be immunosuppressive by viruses, CAV or Reo or bacterial contamination in the hatchery. This needs further research.

see also: Pictures of Viral Diseases in Poultry

One day, I was called by a breeder to come to his layer farm. I get this problem on his pullets, 12 weeks old.
Two days later, I was called again by another breeder located about 85 km from the first farm. I get the same problem. In the same age chicken and the same hatchery as the first farm. Maybe this is a correlation. This needs further research.

Infectious Bursal Disease is a disease that can lead to immunosuppressive. I get thousands of times IBD cases, but this case is not related to immunosuppressive by IBD virus. Maybe CAV virus needs to be suspicious. May be,..

There is no effective treatment in severe cases. Antibiotics do not help much for severe degenerative on the head of the femur. Increasing mineral feeds such as calcium is also not a solution.

This article as a classroom discussion material for veterinary students, avian vet, vet tech students, veterinarian, lectures, professionals, farmers & breeders, and researchers. Field case studies, teaching material for lectures in veterinary schools.
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