139. Atrophic rhinitis of swine.

Question 1

Occurrence ethiology and epidemiology?

Answer 1

OCCURRENCE, ETIOLOGY AND EPIDEMIOLOGY

• Infection is widespread, clinical form is getting rare because of effective preventive methods
• Caused by toxin producing B. bronchiseptica and toxin producing P. multocida D or A
• Dermonecrotoxin, virulence variants
• Introduction with subclinical infected pigs, other species can also be source of infection
• Predisposing factors
• transport,
• mixing,
• quality of air in stable (humidity, NH3, dust, temp),
• overcrowding
• Clinical forms : progressive (more severe clinical signs) and non-progressive form (milder)
• Great economic impact, generally not lethal

Question 2

Pathogenesis?

Answer 2

PATHOGENESIS

• Infection early: suckling piglets or inhalation,
• late: asymptomatic, bacterium carriage
• Maternal protection in piglets of older sows
• Toxic B. bronchiseptica susceptibility decreases with age
• Cause inflammation (caused partially by bacterium and dermonecrotoxin) of the mucous membrane of the nasal cavity,
• mild atrophy of the turbinate bones (dermonecrotoxin will attack the bones)
• Reversible if no p. multocida infection, animals will recover
• Toxic P. multocida the toxin damages the osteoblast cells
• Cause inflammation of the mucous membranes of the nasal cavity,
• atrophy of turbinate bones,
• nasal septum, ethmoid bone, absorption of the turbinates
• deformation of the nose
• Filtration by the nose will be decreased
• Irreversible, toxin is absorbed
• general effects (immunosuppression)

Question 3

Clinical signs?

Answer 3

CLINICAL SIGNS

• Piglets of 1-4 weeks
• rhinitis,
• nasal discharge,
• sneezing,
• blood present in the nares
• Above 3 months of age
• block of lacrimal channel
• (as a result of distortion of the bones) and the skin around the eyes will be wet,
• deformation of the nose,
• wrinkles on the nose (if replication is happening on both sides of the nasal cavity)

Question 4

Pathology?

Answer 4

PATHOLOGY

• Early phase (suckling piglets)
• inflammation of the mucous membrane of the nasal cavity
• do not generally die
• so do not usually see post mortem lesions
• Later phase
• Retardation of growth
• If you saw the nose behind the first premolar tooth will see: atrophy of turbinates, nasal septum,
• ethmoid, nasal septum is twisted, absorption of turbinates
• Shortening of the maxilla (if bilateral infection)

Question 5

Diagnosis?

Answer 5

DIAGNOSIS

• Epidemiology , clinical signs, (post mortem lesions),
• Slaughter house finding ʹ not to easy to notice, because the animals are halved
• Live animals ʹ X-ray and CT (not very practical)
• Bacteriological examination ʹ
• Bacterium isolation from the nasal cavity (not enough alone)
• Detection of toxin production ʹ PCR (gene), ELISA, cell culture ʹ nasal discharge is used

Question 6

Treatment?

Answer 6

TREATMENT

• Antibiotics
• Suckling piglets
• tetracyclines in the feed,
• parenteral or spray, but remain carriers
• Adult pigs cannot be treated

Question 7

Prevention?

Answer 7

PREVENTION

• General epidemiological measures
• Keeping older sows in breeding,
• breeding of infected animals has to be avoided, optimal environment
• Vaccines: Inactivated bacterium, toxoid
• Vaccination of pregnant sows 2 times in last month of pregnancy
• provide maternal ab to piglets
• (piglets are vaccinated in the US)
• Antibiotics ʹ sows and/or piglets (now do not give preventively)
• Eradication ʹ elimination of carrier animals (but not easy to recognize), SPF ʹ specific pathogen free