What causes a pig to be unable to stand or to walk with a lame leg?
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What is going on when a pig cannot stand up or walks with a lame leg?
An affected pig lies on the ground unable to rise; if it is grasped by the tail it can still stand but has difficulty walking, which is called "leg lameness"; if it cannot stand even when grasped by the tail, it is called "paralysis”。Leg lameness is due to pain, mostly caused by damage to bones, muscles, ligaments, tendons (commonly known as "sinews"), joints and the hoof;paralysis is due to nerves, mostly caused by functional disorders of the nerve centers, neuromuscular junctions or motor nerves.
I. Leg lameness
1. Identifying the cause of leg lameness in pigs by the damaged site：
(1) Bone:
This includes the periosteum, bone substance and bone marrow, and is mainly composed of organic matter such as collagen and inorganic matter such as calcium phosphate; the former determines the toughness of the bone, and the latter determines its hardness.Bone damage is commonly seen in:① Bone fissures and fractures caused by external force during group transfer, showing pain, swelling, subcutaneous bruising, and refusal to stand;② Dislocation of the hip bone caused by wet and slippery pens, showing bulging on one side of the rump; the pig can still walk when driven but prefers to lie down;③ Osteomalacia or rickets caused by calcium and phosphorus metabolism disorders, showing staggering gait, no tenderness on pressure, and body deformities, etc.
(2) Muscle:
The basic structural and functional unit of muscle fiber (muscle cell) contraction is the sarcomere, formed by myosin (thick filaments) and actin (thin filaments) intertwined with each other; the two slide against each other to complete the muscle contraction action.Muscle damage is commonly seen in:① Strain caused by weight bearing (such as a boar being too heavy during natural mating) or by slipping and extreme stretching of the limb, showing local pain, tenderness, muscle tension and hardness, sometimes accompanied by hematoma, and difficulty walking;② Muscle spasm caused by strenuous exercise (commonly known as cramp, continuous involuntary tonic contraction of muscle), showing sudden lying down and struggling; after being forced to stand and continue moving, the lameness gradually lessens;
(3) Ligament or tendon:
The difference between the two: they are two completely different tissue structures. A ligament is white band-like connective tissue, relatively tough and elastic, used for the connection between bone and bone, and can also fix the position of organs such as the liver, spleen and kidneys;whereas a tendon is a cord-like or membrane-like dense connective tissue at both ends of the muscle belly, used for the connection between bone and muscle; tendons can conduct electrical signals via nerves, but ligaments cannot.Ligament and tendon injuries are commonly seen in:Strain caused by falling while fighting or being driven to run, showing restricted bending, obvious tenderness and a stiff, taut feeling, accompanied by internal bleeding or hematoma;
(4) Joint:
A joint is composed of the articular surface, joint capsule and joint cavity, realizing the indirect connection between bones.Joint damage is commonly seen in:① Joint inflammation caused by Streptococcus, swine erysipelas, etc., showing lumps at the joint, tenderness, and pus accumulation in severe cases; over a long period it causes bone deformation;② Joint cavity effusion caused by Haemophilus parasuis, etc., showing swelling of the whole leg, difficulty bending when walking, and a goose-step gait;③ Gout caused by low-quality protein raw materials, with urate deposits in the joint cavity, showing enlarged joints and careful, cautious walking;④ Joint sprain caused by climbing around the pen, showing joint swelling, severe pain, limited movement, and subcutaneous bruising around the joint but no fluid when the joint is needled.⑤ Rheumatism caused by cold, damp pens, related to autoimmune disorder; rheumatoid factor and immunoglobulin form immune complexes that deposit at the joints, showing a preference for lying down, no tender points, and symptoms gradually easing after forced exercise.
(5) Hoof:
The hoof is composed of a dead tissue shell and living cells that can produce keratin, including a very hard keratinous outer wall, a hard sole and a softer hoof bulb horn; the hoof bulb horn wraps around the hoof bulb and can cushion the pressure borne by the hoof, like a pad.The keratinous outer shell of the hoof and the keratin-producing cells have no blood vessels or nerves and cannot feel pain; the dermis has blood vessels supplying nutrition to the keratin-producing cells and also has nerves, so it can feel pain.Hoof damage:It is mostly caused by disease factors such as foot-and-mouth disease, hoof cracks caused by biotin deficiency, puncture wounds and other hoof injuries and damage to the dermis. When the pig walks, its own pressure makes the injured hoof feel painful, showing reluctance to bear weight on the hoof and a hopping gait; the specific injured site and type of injury can be identified.
2. Identifying leg lameness in pigs by predisposing causes:
(1) Toe and hoof ulceration: commonly seen in foot-and-mouth disease, etc.(2) Hoof cracks or deformation: commonly seen in nutritional factors such as biotin deficiency(3) Traumatic type: commonly seen in puncture wounds, cuts, bites, tendon or muscle strain, bone damage or displacement, improper intramuscular injection, etc.(4) Inflammatory type: commonly seen in Streptococcus, Haemophilus parasuis, swine erysipelas, Mycoplasma infection, etc.(5) Metabolic disorder type: commonly seen in gout, etc.(6) Allergic reaction type: commonly seen in rheumatism, etc.
3. Treatment of leg lamenessTreatmentprinciples:
Commonly used antibiotics such as cephalosporins, lincomycin and sulfonamides + non-steroidal antipyretic and analgesic drugs such as salicylic acid for indistincttreatment。
II.Paralysis
Limb movement is controlled by nerves. The lowest control center is in the spinal cord, the highest control center is in the cerebral cortex, and different levels of centers in between also participate. When the relevant nerve centers, peripheral nerves or neuromuscular junctions are damaged, loss of voluntary movement function is paralysis.It is divided into monoplegia (paralysis of one limb), hemiplegia (paralysis of one side of the body), crossed paralysis (paralysis of the left forelimb and right hindlimb, or of the right forelimb and left hindlimb), quadriplegia, paraplegia (paralysis of both forelimbs or both hindlimbs), etc.
1. Common types of paralysis:
(1) Spinal cord type paralysis: such as porcine infectious encephalomyelitis, etc., showing persistent spastic paralysis below the level of the injury.(2) Brain type paralysis: such as encephalitis caused by pseudorabies, etc., showing coma, vomiting, meningeal irritation signs, tremor, etc.(3) Peripheral nerve damage: such as polyneuritis caused by vitamin B2 deficiency, with loss of motor and sensory function in the area innervated by the nerve, showing muscle flaccidity, atrophy, loss of reflexes, and temporary paralysis.(4) Neuromuscular junction type paralysis: such as aminoglycoside drug poisoning, etc., showing general paralysis and difficulty breathing.(5) Muscle type paralysis: such as postpartum paralysis in sows, etc., showing normal spirit and appetite, inability to rise from lying down, and reflexes present when needled.
2. Treatment of paralysisTreatmentprinciples:
Either find the cause and treat the causetreatment, or cull;to relieve symptoms, indistincttreatmentcommonly uses sulfamonomethoxine sodium + troxerutin by intramuscular injection.
