SWINE MEDICINE FINALS (Disease identification)

A 10-week-old grower pig from a commercial farrow-to-finish farm is presented because of persistent sneezing that began approximately three weeks ago. Initially, the attending veterinarian suspected environmental irritation since no fever or coughing was observed. Over the following days, the pig developed a serous nasal discharge that later became blood-tinged, and the caretaker reports occasional episodes of profuse nasal bleeding.

On physical examination, the pig is bright and alert. There is tear staining below the medial canthus of both eyes, and the upper jaw appears slightly shortened with deviation toward the left side. Several pen mates exhibit similar signs, although some only have sneezing without obvious facial deformities.

A necropsy is performed on one severely affected pig. Cross-sections of the skull at the level of the second premolar tooth reveal marked softening and atrophy of the nasal turbinates, deviation of the nasal septum, and asymmetrical distortion of the surrounding bony structures. The nasal cavity is otherwise relatively free of exudate.

Atrophic Rhinitis

A commercial swine farm reports reproductive failure in several pregnant sows during the last month. Affected sows have delivered multiple mummified fetuses, stillborn piglets, and some piglets that died within the first few days after birth.

Among the surviving litters, piglets 5–10 days of age develop moderate to severe rhinitis characterized by profuse, sticky nasal discharge and conjunctivitis with copious ocular discharge. The farm veterinarian notes that piglets born to immune sows are less severely affected, while piglets lacking adequate colostrum intake have a much higher mortality rate.

Interestingly, growers and finishing pigs on the farm appear clinically normal despite being housed in the same facility.

Necropsy of an affected piglet reveals no significant pneumonia, but histopathologic examination of the nasal mucosa demonstrates basophilic intranuclear inclusion bodies. Similar inclusion bodies are also observed in the viscera of aborted fetuses. The veterinarian recommends confirming the diagnosis using PCR or ELISA.

Inclusion Body Rhinitis

A farrow-to-wean swine farm reports that several 3-week-old piglets have developed progressive swelling around the snout and face. The farm manager mentions that all piglets had their needle (milk) teeth clipped shortly after birth, but the procedure was difficult because the clippers were dull and left rough edges on several teeth.

Within the next two weeks, a few piglets began snuffling and sneezing, followed by a thick, foul-smelling nasal discharge. As the condition progressed, the affected piglets developed marked swelling and deformity of the face, accompanied by loss of appetite and progressive weight loss. Some piglets also exhibited bloody nasal discharge, excessive tearing, and purulent ocular discharge.

On physical examination, the facial swelling is firm and painful. An incision into the swollen area releases a large amount of pinkish-gray, foul-smelling necrotic tissue mixed with greenish-gray debris. Radiographs reveal destruction of the nasal and facial bones, explaining the severe facial deformity.

The veterinarian suspects that bacteria entered through wounds in the oral and nasal mucosa created during the improper clipping of the piglets' milk teeth.

Necrotic Rhinitis (Bull nose)

A commercial grower-finisher swine farm housing 2- to 4-month-old pigs reports a persistent respiratory problem that has gradually spread throughout the herd. The pigs are kept in overcrowded, poorly ventilated buildings with inadequate sanitation.

The farm manager notes that very few pigs die, but many pigs have been coughing for several weeks. Interestingly, the coughing becomes much more obvious whenever the pigs are disturbed or forced to stand and move during feeding or handling. Most affected pigs remain alert and continue eating, although some have reduced growth performance.

The veterinarian observes that morbidity is high, but the clinical illness is generally mild. The owner mentions that the disease appeared much more severe when it first entered the herd several months ago.

Necropsy of several affected pigs reveals well-demarcated gray to purple areas of lung consolidation, primarily involving the apical and cardiac lobes, while the diaphragmatic lobes appear unaffected. The associated bronchial lymph nodes are enlarged.

Histopathologic examination demonstrates peribronchiolar and perivascular lymphoid cuffing (lymphoid hyperplasia) surrounding the bronchioles and blood vessels.

Enzootic Pneumonia

A commercial swine farm suddenly experiences a severe respiratory disease outbreak among its grower pigs (4–5 months old). Within 48 hours, the disease spreads rapidly through several pens. The farm manager reports that some pigs were found dead without showing any previous signs of illness.

The surviving affected pigs have high fever (41.4°C), refuse to eat, and are reluctant to move. Many are observed breathing rapidly with shallow respirations ("thumping"). Several pigs have profuse frothy, blood-tinged nasal discharge, with similar blood-stained froth coming from the mouth. A few pregnant gilts in the affected group have recently aborted.

The outbreak affects nearly half of the herd, and deaths continue despite treatment. Pigs that recover remain thin and continue to have a persistent cough with poor growth performance.

Necropsy of a freshly dead pig reveals that all lung lobes are dark red to black, swollen, and heavy. When the lungs are cut, blood and fluid ooze from the surface. The trachea contains blood-stained froth, and there is marked fibrinous pleurisy and pericarditis. Multiple necrotic bullae are scattered throughout the lungs. In one chronic case, osteomyelitis is also observed.

Pleuropneumonia

Make a clinical case scenario where I will identify this disease based on the information given:

Disease: Glasser's Disease

Definition: A fibrinous, occasionally

fatal, polyserositis,

Polyarthritis and meningitis

of pigs. Precipatated by

stress, overcrowding, no

accesss to feed

Distinguishing clinical sign and lesion

Cheese cloth appearance upon opening of the thoracic and abdominal cavity. Joint fluid is turbid with greenish fibrin deposits and Polyyarthritis is the last sign to be seen.

Clinical signs:

Mild type, with low

morbidity

Severe type with high

morbidity and mortality

Incubation period is 1-5

days, disease occurring 2-7

days after precipitating

stress

Young (weaning –

4months) are usually

affected,

Fever (41-42C)

Anorexia, Depression,

Mild rhinitis, Dyspnea,

Coughing, Emaciation

Lesions:

Fibrinopurulent pleurisy

Pericarditis, peritonitis

Bronchopneumoniae

Fibrinopurulent

meningoencephalitis

Joint fluid is turbid with greenish

fibrin deposits

Inflamed periarticular tissues

Fibrin deposit in joint capsule

Age affected; Young pigs (after weaning up to 4 months of age)

Glasser’s disease (Porcine Polyserositis, Infectious polyarthritis)

A commercial farrow-to-finish swine farm reports a sudden respiratory disease outbreak affecting pigs of different age groups. Within 72 hours, nearly all pens contain coughing pigs. The disease spreads rapidly despite immediate isolation of affected animals.

Affected pigs develop high fever, depression, anorexia, weakness, and dyspnea. Most are reluctant to move and spend much of the day lying down. They exhibit frequent coughing accompanied by mucoid discharge from the eyes and nose. Although many pigs become sick, only a small percentage (about 2%) die. Several late-gestation sows abortduring the outbreak.

Interestingly, after 5–7 days, most pigs recover almost as quickly as they became ill. However, over the following weeks, the farm manager notices that many recovered pigs fail to reach their expected market weight because respiratory signs continue to recur within the herd.

Necropsy of an affected pig reveals well-demarcated, collapsed, purplish-red areas of pneumonia affecting all lung lobes, but the lesions are confined mainly to the ventral portions of each lobe. The unaffected lung tissue appears pale and emphysematous. The bronchi contain mucopurulent exudate, while the bronchial and mediastinal lymph nodes are edematous. There is marked pulmonary edema, especially in the interlobular septa, and the pleural cavity contains serous to serofibrinous exudate.

Swine Influenza virus (Hog flu, Pig flu)