Todayโs path rounds are on ๐ค๐ข๐ง๐ค๐ฒ ๐๐๐๐ค!
๐๐ก๐๐ญ ๐ข๐ฌ ๐ข๐ญ?
๐๐ข๐ง๐ค๐ฒ ๐๐๐๐ค actually refers to two different conditions in chickens, somewhat confusingly. Both of these diseases result in similar clinical signs, hence being grouped under the same name.
The first condition is ๐ฌ๐ฉ๐จ๐ง๐๐ฒ๐ฅ๐จ๐ฅ๐ข๐ฌ๐ญ๐ก๐๐ฌ๐ข๐ฌ, which is a developmental disorder affecting the spine. In this condition, one of the ๐ญ๐ก๐จ๐ซ๐๐๐ข๐ ๐ฏ๐๐ซ๐ญ๐๐๐ซ๐๐ (vertebrae that are in the thorax) becomes displaced, giving the spine a โstepโ and compressing the spinal cord.
The second condition is ๐๐ง๐ญ๐๐ซ๐จ๐๐จ๐๐๐๐ฅ ๐ฌ๐ฉ๐จ๐ง๐๐ฒ๐ฅ๐ข๐ญ๐ข๐ฌ, a bacterial infection that causes masses near the spine that compress the spinal cord. This infection particularly targets the thoracic vertebrae as well.
๐๐ก๐จ ๐ ๐๐ญ๐ฌ ๐ข๐ญ?
Both conditions are primarily seen in ๐๐ซ๐จ๐ข๐ฅ๐๐ซ ๐๐ก๐ข๐๐ค๐๐ง๐ฌ (chickens we eat!) however it can also be seen in other birds as well.
๐๐ก๐๐ญ ๐๐๐ฎ๐ฌ๐๐ฌ ๐ข๐ญ?
Spondylolisthesis is believed to be caused by a genetic issue, that causes spinal deformity when combined with the rapid growth rate of broiler chickens.
Enterococcal spondylitis on the other hand is caused by ๐๐ง๐ญ๐๐ซ๐จ๐๐จ๐๐๐ฎ๐ฌ ๐๐๐๐จ๐ซ๐ฎ๐ฆ, a bacteria normally found in the intestinal tract of chickens. In this disease, the bacteria enters the bloodstream through the intestinal tract and colonizes in pre-existing ๐จ๐ฌ๐ญ๐๐จ๐๐ก๐จ๐ง๐๐ซ๐จ๐ฌ๐ข๐ฌ ๐๐ข๐ฌ๐ฌ๐๐๐๐ง๐ฌ (a defect in the development of a bone) lesions in the thoracic vertebrae. From there, a massive bacterial infection develops that compresses the spinal cord.
๐๐ก๐ฒ ๐ข๐ฌ ๐ญ๐ก๐ข๐ฌ ๐ ๐ฉ๐ซ๐จ๐๐ฅ๐๐ฆ?
Compression of the spinal cord causes the chickens to be unable to walk or move properly. They are often found sitting on their tail with their legs extended forwards, or trying to โwalkโ using their wings to pull themselves around. Because these birds canโt move, they are unable to get to food and water, and quickly succumb to starvation or dehydration.
๐๐จ๐ฐ ๐ข๐ฌ ๐ข๐ญ ๐๐ข๐๐ ๐ง๐จ๐ฌ๐๐?
The best method for diagnosis is cutting the spinal cord in half during necropsy. This allows the veterinarian or pathologist to directly visualize the spinal cord compression and what is causing it.
๐๐จ๐ฐ ๐ข๐ฌ ๐ฉ๐ซ๐๐ฏ๐๐ง๐ญ๐๐?
For spondylolisthesis, selecting animals that have not had cases in their pedigree is the best means of prevention, since the disease has a genetic link.
For enterococcal spondylitis, researchers are currently working on a vaccine against Enterococcus cecorum that could be added into routine vaccination protocols for all chickens. Currently however, the best means of prevention is reducing environmental contamination with the bacteria by keeping barns super clean!
๐๐ก๐จ๐ญ๐จ๐ฌ
1) A chicken sitting on its tail from kinky back.
2) A chicken attempting to โwalkโ using its wings.
3-4) Examples of spinal sections showing spondylolithesis โstepsโ.
5-6) Examples of enterococcal spondylitis showing the large bacterial mass that compresses the spinal cord.
๐๐จ๐ฎ๐ซ๐๐๐ฌ
Van Wettere, A.J. Noninfectious skeletal disorders in poultry broilers. Merck Veterinary Manual 2020.
Borst, L.B., Suyemoto, M.M., Sarsour, A.H., Harris, M.C., Martin, M.P., Strickland, J.D., Oviedo, E.O. and H.J. Barnes. Pathogenesis of Enterococcal Spondylitis caused by Enterococcus cecorum in Broiler Chickens. Veterinary Pathology 2017, Vol 54(1).
Dinev, I. Pathomorphological investigations on the incidence of clinical spondylolithesis (kinky back) in different commercial broiler strains. Revue de Medecine Veterinaire 2012.
Photos 1-3 courtesy of I. Dinev.
Photos 4-5 courtesy of Noahโs Arkive.
Photo 6 courtesy of L.B. Borst et al.
