Paralysis of a pig’s limbs is a symptom of porcine infectious encephalomyelitis
Cause: Porcine infectious encephalomyelitis is transmitted mainly between wild boars and pigs. Pigs of all breeds and ages are susceptible, and piglets are more susceptible than adult pigs. Adult pigs generally have subclinical infections: they carry the virus but show no symptoms. Pigs with subclinical infections act as a means of spreading the virus.
The virus is shed in the feces of infected pigs. Infection occurs when contaminated feed or drinking water enters the body. This is how pigs become infected with porcine infectious encephalomyelitis. The disease can also spread through the respiratory system. Newly affected areas often experience outbreaks, while areas where the disease has been present for a long time typically see sporadic cases. Pigs that recover from porcine infectious encephalomyelitis generally do not become infected again.
Clinical symptoms: The incubation period of acute porcine infectious encephalomyelitis is generally 4—28 days, depending on the inoculum and the virulence of the virus. In the early stage of infection, the body temperature of affected pigs gradually rises to 41—42℃, and may rise even higher. Pigs with infectious encephalomyelitis are in poor condition and may show symptoms such as uncoordinated movement and loss of appetite. As the disease progresses to a certain stage, signs of encephalitis may appear, including convulsions, eye tremors, and stiff limbs; clonic seizures may also occur. When startled, affected pigs may develop opisthotonus. Affected pigs generally die 3—4 days after symptoms appear. Some individual cases may persist for a period before dying or may survive, but may be left with sequelae such as muscle atrophy and paralysis of the legs and feet.
Subacute porcine infectious encephalomyelitis is milder in presentation, so its morbidity and mortality are relatively low. However, nursing pigs aged 14 days show more severe symptoms, and most affected pigs can recover. It should be noted that the morbidity and mortality rates among newborn piglets are 100%; piglets generally rarely become ill once they are over 21 days old. Subacute porcine infectious encephalomyelitis develops rapidly and also subsides quickly. The main signs in affected pigs are reduced appetite and a slight rise in body temperature, followed by neurological signs after several days. Piglets aged 14 days generally sit like dogs, show ataxia, and walk backward, eventually developing signs of encephalitis.
What should be done about paralysis of a pig’s limbs?
Diagnostic methods: Porcine infectious encephalomyelitis can be diagnosed based on epidemiological features, clinical and anatomical signs, and central nervous system signs. Affected pigs are in poor condition and show uncoordinated movement, convulsions, eye tremors, ataxia, a dog-sitting posture, and backward walking. Necropsy reveals cerebral edema, congestion of cerebral blood vessels, and atrophy of skeletal and cardiac muscles. Porcine infectious encephalomyelitis should be differentiated from diseases with the same or similar signs, such as porcine hemagglutinating encephalomyelitis and pseudorabies. These are the diagnostic methods for porcine infectious encephalomyelitis.
Prevention: Preventing porcine infectious encephalomyelitis requires strict quarantine of introduced breeding pigs, prompt isolation and treatment or culling of affected pigs, strict disinfection around the pig farm, and a series of other measures. In terms of controlling porcine infectious encephalomyelitis, foreign media reports state that immunization can be carried out using live attenuated vaccines, cell-culture inactivated vaccines, and aluminum hydroxide inactivated vaccines. The immunization rate for live attenuated vaccines can reach more than 80%, and the immunity period can reach 6-8 months; aluminum hydroxide inactivated vaccines and cell-culture inactivated vaccines have lower immunization rates. Because there are many serotypes of porcine infectious encephalomyelitis, when vaccines are needed in routine practice, it is recommended to use vaccines containing multiple serotypes.
Treatment: There are currently no significant treatment measures for porcine infectious encephalomyelitis. When a pig herd is affected, targeted treatment is generally chosen. Treatment by injecting serum from recovered pigs into affected pigs may be attempted, but it is not very effective against porcine infectious encephalomyelitis. Therefore, when an outbreak is detected in a pig herd, be sure to take control measures, promptly develop a response plan, provide emergency diagnosis and treatment, isolate and cull affected pigs to prevent the outbreak from spreading, isolate healthy pigs for observation, strengthen disinfection measures, promptly remove suspected affected pigs, and control the disease.
Veterinary experts advise that if porcine infectious encephalomyelitis is detected on a pig farm, do not use medication indiscriminately. Be sure to consult a professional veterinarian and treat porcine infectious encephalomyelitis as directed by the veterinarian.