What can we do today to reduce the problem?

Kinky back (spondylolisthesis) in broiler chickens

Published: September 29, 2023

By: Dr. Marconi Italo Lourenco da Silva, Sao Paulo State University; Dr. Leonie Jacobs, Virginia Tech. Reviewers: Dr. Prafulla Regmi, University of Georgia; Dr. Marisa Erasmus, Purdue University; Dr. Bethany Baker-Cook, Auburn University.

Kinky back (spondylolisthesis) in broiler chickens: what we can do today to reduce the problem? - Image 1

Spondylolisthesis, often called ‘kinky back’, is a deformity that affects broiler chickens’ spines. The deformity occurs in the fifth and/or sixth vertebrae (T6) and leads to spinal cord compression making it hard for birds to walk, and in severe cases it can cause paralysis. Chickens are lame and will sit with extended feet, show an imbalance, and fall on their side when attempting to stand.

Walking ability, or gait, is related to this condition. Even when the deformation is subclinical, meaning not obviously detected, birds may have spinal compression and poor walking ability, suggesting they are in pain.

Kinky back (spondylolisthesis) in broiler chickens: what we can do today to reduce the problem? - Image 2

This newsletter describes some characteristics of this disorder and some preventive methods to reduce the prevalence of this condition in a broiler chicken flock.

Development and prevalence of subclinical and clinical spondylolisthesis

Kinky back (spondylolisthesis) in broiler chickens: what we can do today to reduce the problem? - Image 3

This condition can affect chickens between 3 and 6 weeks of age before it evolves into clinical (observable) cases. When it's not obvious and does not show observable signs, it is called "subclinical" spondylolisthesis.

Subclinical spondylolisthesis can affect 15 - 60% of a flock. Clinical spondylolisthesis is a severe health and welfare concern and can affect 2% of a flock. When spondylolisthesis evolves into a clinical condition, the bird must be euthanized to end pain and distress.

Chickens with subclinical spondylolisthesis do not show symptoms, while broilers with clinical spondylolisthesis are unable to walk, will have an abnormal sitting posture, are unbalanced, and may fall over when attempting to stand.

Kinky back (spondylolisthesis) in broiler chickens: what we can do today to reduce the problem? - Image 4

What we can do to limit the issue?

The prevalence of subclinical spondylolisthesis and the possible development to clinical cases can be reduced by providing environmental resources that increase complexity. These resources will stimulate birds’ activity and thus provide opportunities for birds to exercise and walk more than they would without these items.

Some suggested resources to promote exercise are:

Perching platforms with or without ramps depending on the height
Straw or hay bales
Laser light projections onto the floor

These resources increase exploratory behaviors, positive activity, and walking. This can strengthen the locomotor system, alleviate the pressure of the bird’s body weight, and reduce the prevalence of subclinical spondylolisthesis.

Step platforms provide means for exercise, such as walking up, down, and jumping off the platforms. Hay bales and laser lights stimulate exploratory behavior, such as chasing and pecking. These resources reduced subclinical spondylolisthesis prevalences in this study.

Kinky back (spondylolisthesis) in broiler chickens: what we can do today to reduce the problem? - Image 5

Researchers found that platform perches were most effective in reducing the prevalence of subclinical spondylolisthesis, with 21% of the flock impacted, compared to almost 60% of the flock in the control group, without added resources. Laser lights reduced the prevalence to 29%. Possibly, a combination of these resources, or more resources, may reduce the prevalence of subclinical spondylolisthesis even further.

“Kinky back” is a multifactorial problem

Providing resources to increase complexity does not prevent the issue completely, although it can reduce the prevalence significantly. Many factors contribute to the development of the disorder, including genetic predisposition, nutrition, age, stocking density, incubation conditions, and bedding materials.

In summary

Kinky back can negatively affect fast-growing broilers even without obvious signs.
Kinky back is a multifactorial disorder. There is no magical solution, as both genetic and environmental factors impact the prevalence.
Environmental resources stimulate exploratory behaviors and exercise, strengthening the birds’ musculoskeletal systems.
Environmental complexity can reduce subclinical spondylolisthesis prevalences in broilers.

This article was originally published on Poultry Extension Collaborative (PEC) and it is reproduced here with permission from the authors.

References

Abbasabadi, B. M., Golshahi, H., & Seifi, S. (2021). Pathomorphologial investigation of spondylolisthesis leaded to spondylosis in commercial broiler chicken with posterior paralysis: A case study. Veterinary Research Forum, 12(2), 263–265.

Almeida Paz, I., Garcia, R., Bernardi, R., Nääs, I., Caldara, F., Freitas, L., Seno, L., Ferreira, V., Pereira, D., & Cavichiolo, F. (2010). Selecting appropriate bedding to reduce locomotion problems in broilers. Brazilian Journal of Poultry Science, 12(3), 189–195.

Crespo, R., & Shivaprasad, H. L. (2008). Developmental, metabolic and other diseases. In Y. M. SAIF, A. M. FADLY, J. R. GLISSON, L. R. MCDOUGALD, L. K. NOLAN, & D. E. SWAYNE (Eds.), Diseases of poultry (12th ed., p. 1159). Blackwell publishing.

Dinev, I. (2012). Pathomorphological investigations on the incidence of clinical spondylolisthesis ( kinky back ) in different commercial broiler strains. Revue Med Vet, 163(11), 511–515.

Howlett, C. R., & Wood, A. K. W. (1984). A radologic and pathologic study of paresis in broiler chickens associated with noninfectious vertebral abnormalities. Veterinary Radiology, 25(2), 72–72.

Julian, R. J. (2004). Evaluating the Impact of Metabolic Disorders. In C. A. Weeks & A. Butterworth (Eds.), Measuring and auditing broiler welfare (pp. 51–59). CABI Publishing.

Kelly, W. R. (1971). Occurrence of spondylolisthesis (kinky-back) in broiler chickens in South Australia. Australian Veterinary Journal, 47(73).

Lourenço da Silva, M. I., Almeida Paz, I. C. de L., Chaves, G. H. C., Almeida, I. C. de L., Ouros, C. C. dos, Souza, S. R. L. de, Milbradt, E. L., Caldara, F. R., Satin, A. J. G., Costa, G. A. da, & Glavina, A. S. G. (2021). Behaviour and animal welfare indicators of broiler chickens housed in an enriched environment. PLOS ONE, 16(9), e0256963.

Lourenço da Silva, M. I., Almeida Paz, I. C. de L., Jacinto, A. S., Nascimento Filho, M. A., Oliveira, A. B. S. de, Santos, I. G. A. dos, Mota, F. dos S., Caldara, F. R., & Jacobs, L. (2023). Providing environmental enrichments can reduce subclinical spondylolisthesis prevalence without affecting performance in broiler chickens. PLOS ONE, 18(4), e0284087.

Osbaldiston, G. W. (1967). Spondylolisthesis and leg weakness in the chicken-a common etiology. Veterinary Record, 80, 320–322.

Wise, D. R. (1970). Spondylolisthesis (‘Kinky Back’) in Broiler Chickens. Research in Veterinary Science, 11(5), 447–455.

Wise, D. R. (1973). The Incidence and Aetiology of Avian Spondylolisthesis (‘Kinky Back’). Research in Veterinary Science, 14(1), 1–10.