Insults and Agents Affecting Ambulationin Pigs^a

Traumatic

Fractures of long bones or vertebrae

Acute or chronic. Outbreaks may have underlying nutritional component. See "metabolic bone disease" under nutritional or toxic insult type below.

Electric shock

Lumbosacral vertebral fractures; lethal or sublethal.

Iatrogenic muscular dystrophy

Motor nerve trauma. Poor injection placement (ham or paravertebral). Irritating injectables and adjuvants.

Fibrocartilaginous emboli

Paresis, paralysis in finishing pigs; can occur with metabolic bone disease.

Foot (hoof, claw) lesions

Direct or indirect contributor via pain, bacterial infection.

Athletic injury

Bruising, swelling, joint or muscle pain.

Sunburn

Crouching or swayback behavior in response to dorsal pain.

Infectious

Bacterial myelitis

Bacterial meningitis

(See the table Common Bacterial Agents Associated With Lameness)

Trauma from tail biting, facial or ear necrosis, abrasions, wounds. Usually endemic bacteria.

Viral myelitis, encephalitis

Vesicular diseases

(See the table Viral Agents That May Contribute to Lameness Expression or Ataxia)

Ataxia, paresis, central paralysis, or peripheral nerve effects. Sporadic outbreaks result in herd immunity for some. Viral infections with direct effect or as risk factors.

Edema disease

Ataxia. Effect of Escherichia coli Shiga-like toxin; can be chronic.

Ear infections, vestibular syndromes

Bacterial meningitis. Chronic otitis interna (eg, Streptococcus suis, Mycoplasma hyorhinis).

Abscess; brain, spinal cord, other locations

Pyogenic organisms, multiple sites: Trueperella pyogenes, staphylococci, other streptococci.

Tetanus

Wound infection. Clostridium tetani, tetany.

Parasitic migration

Encephalitis or myelitis. Rare. Outdoor rearing.

Cerebellar hypoplasia

In utero viral infections (eg, Japanese encephalitis virus, Menangle virus, pestiviruses).

Nutritional or toxic

Osteochondrosis, epiphysiolysis, apophysiolysis

Multifactorial: heavily muscled fast-growing genotypes, with nutritional, traumatic, environmental and infectious risk factors.

Metabolic bone disease

Investigate bone integrity; calcium (Ca), phosphorus (P), vitamin D, phytase effects.

Inanition or hypoglycemia

Weakness, coma in suckling piglets.

Kyphosis

Metabolic bone disease in young pigs; “hump back.”

B-vitamin deficiencies

Hoof integrity (biotin); CNS (thiamin, B vitamins).

Micronutrient deficiencies

Malformation or stunting; vitamin A, copper (Cu), manganese (Mn) deficits.

Sodium (Na) toxicity

Water deprivation or excess sodium.

Selenium (Se) toxicity

Mixing error: hair or hoof sloughing, spinal cord lesions.

Ionophore +/– tiamulin

Mixing errors. Tiamulin treatment promotes toxicity.

Organophosphates

Aryl phosphate (delayed)

Typical CNS signs. Exposures to insecticides, chemicals. Paresis with exposures to hydraulic or transformer fluids.

Pigweed, cocklebur, etc

Access to toxic plants. Necropsy and investigation of premises.

Arsenic, metals (lead [Pb], mercury [Hg])

Feed mixing errors or contamination as sources.

Congenital or neonatal

Congenital tremors

Tremors of intent. Usually atypical porcine pestivirus. Rarely genetic or toxin-induced.

Cerebellar abiotrophy

Rare. Develop paresis by 4 weeks.

Spastic paresis

Rare. Heritable.

Congenital malformations

Cranial or limb abnormality

Causes include various toxins; viruses; vitamin A, Mn deficiencies; genetic defects.

Neonatal maladjustment

Vitamin A, thiamin deficiency. Hypoglycemia. Hypoxia.