Etiological Analysis and differential diagnosis of Chicken leg Diseases

In the process of feeding, chickens often suffer from leg diseases such as soft feet, claudication, paralysis, squatting and unwilling to walk, deformed legs and paws and paralysis. The causes of leg diseases in chickens are extremely complicated. Leg disease is mostly a symptom of a disease, or a type of disease, a very small number of independent diseases, which some people call foot weakness syndrome. The occurrence of leg disease in the flock directly affects the uniformity of the flock and improves the abandonment rate and sporadic mortality of the flock. In this paper, the etiology and characteristics of chicken leg disease are summarized as follows.

Etiological Analysis of Chicken leg Diseases

1. Virus

(1) Newcastle disease

There are many types of the disease. In the subacute or chronic type, it can be seen that the diseased chicken leg wing paralysis, limping, standing instability, head backward or twisted to one side, some one leg paralysis to the metatarsal to the ground, some both legs paralysis, the whole body twitches when frightened, the body rolls.

(2) Infectious encephalomyelitis

The disease, also known as epidemic tremor, mainly occurs in 5-25-day-old chicks, showing vertical and horizontal transmission. At the beginning of the disease, the chicken head and neck tremor, and then gradually appear ataxia, and finally paralysis, can not afford to lie down, two feet extended to one side, until death.

(3) Marek's disease

Most of them occur after the age of 70-80 days. Neurological Marek's disease can invade the sciatic nerve and show dyskinesia, resulting in unilateral or bilateral paralysis, with one limb forward and the other backward in a "split" position.

Viral arthritis (viral tenosynovitis)

Caused by chicken reovirus, this disease is common in broilers at the age of 2 weeks, and obvious symptoms appear at the age of 3 to 4 weeks, such as reluctance to walk, lameness, joint swelling, foot joint bending and deformation, gastrocnemius tendon rupture.

2. Bacteria

(1) Chicken infectious synovitis (mycoplasmosis)

With mycoplasma infection, the affected chicken showed pale crown, stop growth, swollen joints (especially hocks and toe joints), limping, squatting, swelling of tarsal joints or foot mats, and sticky, grayish-yellow exudates in synovial sac.

(2), avian tuberculosis

The diseased chicken is depressed and has obvious weight loss. When the bones are invaded by germs, they show unilateral claudication and walk with a special jumping gait. Intra-articular tuberculosis can cause paralysis.

(3) inclusive hepatitis

The feathers of the chicken are loose, the chicken crown is white and anemic, the liver is yellow and brittle, there are bleeding and necrotic spots, the bone marrow of the thigh is pink or yellow, and extensive bleeding occurs in the chest muscle, leg muscle, subcutaneous tissue and visceral tissue.

(4) bacterial arthritis

It is characterized by inflammatory reactions such as redness, swelling, heat and pain in the legs and joints, causing chickens to limp and squatting unwilling to act. The causes of the disease are staphylococcal infection, campylobacter hepatitis, Escherichia coli infection, salmonella infection, streptococcosis and avian cholera.

(5) Poultry paracillosis

The pathogen is accessory E. coli. The affected chicken has diarrhea, leg paralysis, neck torsion, sitting on the ground with hocks, dyskinesia, body tremors, and sometimes bloody feces.

(6) transient paralysis

According to Bi Yingzuo (Poultry Research Laboratory of South China Agricultural University, 1994), the cause of the disease is not clear. It often occurs in 6-Mel 8-week-old chickens. The affected chickens develop neck and wing flaccid paralysis and complete foot paralysis, and most of them can recover after 1-3 days. After the end of the feeding restriction period, the compression of the vagus nerve due to satiety will also cause a transient paralysis.

(7) Poultry spirochete disease

The pathogen is spirochete. The affected chickens developed anorexia, mental malaise, dishevelled feathers, lethargy, head cyanosis, diarrhea, thirst, unstable walking, and eventually became paralyzed, extremely weak and died.

3. Parasitic

(1) leukozoonosis carinii

The disease only occurred in chickens, and the incidence was the highest at the age of 1-3 days. The main manifestations are depressed spirit, dishevelled feathers, anemia, pale crown, yellow-green sparse feces, walking difficulties, motor disorders, paralysis of both limbs and stunting.

(2) Chicken knee acariasis

Knee mites are usually parasitic on feathers such as shins and feet of chickens. The worms can drill into the skin and tunnel under the scales of the lower legs. As a result of its parasitic inflammation, scaly shavings on the tibia, followed by skin proliferation and roughening, itchy cracks, the exudate from the diseased part dries up to form gray crusts, showing a "right gray foot", leading to difficulty in movement, and even developing arthritis and toe osteonecrosis.

4. Trauma

Mechanical fractures, sprains, inflammation.

5. Nutritional and metabolic diseases

(1) gout

Excessive intake of animal protein in chickens is caused by the obstruction of urate excretion of protein metabolites. Factors that cause renal dysfunction can cause the disease, such as VA deficiency, water deficiency and high calcium diet. Joint gout can be seen in the cartilage, peri-articular tissue, tendon sheath and ligaments of the joint (toe joint). Urate accumulates nodules, making the joint or interphalangeal swelling thicker.

(2) imbalance of Ca and P

The proportion of Ca and P in chicken feed was inappropriate for a long time, and the growing chickens showed weakness in their legs, unstable walking and claudication, and the heavy ones could not afford to lie on their side, and the forks of their legs showed the character of "eight". The number of eggs laid by adults decreased and soft shell eggs were laid. The femur was easy to break and crushed, the femur was soft and flexible, the epiphyseal growth plate widened, the beak became soft as rubber, the keel was "S" shaped, and the ribs and spinal nodes were swollen in a series of balls.

6. Vitamin deficiency

(1) lack of VB1

Causes chicken polyneuritis and peripheral nerve paralysis, suffers from chicken anorexia, weak legs, unstable steps, and inward curling toes. At the beginning, the chicken walks with its head raised and its feet curled inward. With the development of the disease, the hock joint hits the ground and moves, the body bends the leg, the heavy person is paralyzed, lying on the ground, the legs are straight, and the head is back in a "stargazing" posture.

(2) lack of VB2

The affected chicken walks on one foot or on the tarsal joint, the joint is swollen, the toes are curled inward, or one leg is forward and the other is backward, so it is difficult to walk. When walking, the two limbs spread out to maintain balance. Autopsy showed enlargement of the sciatic nerve.

(3) lack of VE

Difficult to walk, paralyzed legs, lying on the side, legs stretched out, one side angle arch dilated, legs spasms and convulsions, and soon died.

(4) choline deficiency

Can cause bone short thick disease, tarsal joint enlargement, the foot bends to the side and produces slippery tendon disease.

(5) nicotinic acid deficiency

When the chicken is lack of nicotinic acid, the leg joints are swollen and the toes and claws are spasmodic. When the growing chicken lacks nicotinic acid, the growth stagnates, the joint is swollen, the bone is short and thick, the leg is bent, and it is difficult to walk.

(6) niacin deficiency

The tarsal joint is swollen and it is difficult to walk.

(7) biotin deficiency

Can cause tendinosis, plantar and toe skin cracking, bleeding, scab, foot pad dermatitis, which is a typical symptom of biotin deficiency.

(8) lack of VA

The leg joint is swollen and there is white urate in the joint capsule, making it difficult to walk.

(9) folic acid deficiency

The diseased chicken has poor growth, abnormal feathers, anemia and short bones, and abnormal walking.

(10) lack of VD3

Extremely weak legs, difficult to walk, the special posture of the body sitting on the legs (crouching position), and then the chicken beak, claws and keels become soft and flexible.

7. Mineral deficiency

(1) lack of Zn

The diseased chickens showed weakness of the legs, dyskinesia, long bones, swollen tarsal joints, phosphorus flakes in the skin of the legs and feet, and necrotizing dermatitis in severe cases.

(2) Manganese deficiency

When manganese deficiency occurs in poultry, it causes thickening of the tibial joint, torsion or bending of the distal tibia and proximal phalanx, and finally slippage from the gastrocnemius tendon, making it difficult to walk.