porcine pathology

Enteric Colibacillosis

• Characterized by dehydration, distention of the small intestine and colon, and yellow, watery mucoid fluid.
• Stomach is dilated and full of feed. May have patchy cutaneous erythema.
• Small intestines show multi-focal, acute catarrhal enteritis.
• Clinical signs include profuse watery diarrhea, rapid dehydration, acidosis, and death.
• Pathogenesis is caused by Enterotoxigenic E. coli.
• Bacteria attach to the acid surface of enterocytes and produce toxins causing a secretory diarrhea.
• Diagnosis involves PCR and culturing.
• Villi (small finger-like projections lining the intestines) are found to be of normal length but have small cocobacilli adhered to erythrocytes (red blood cells).

Enteric Clostridiosis

• Dark-red small intestine filled with bloody fluid.
• Jejunum shows emphysema in the wall and necrosis.
• Small intestine lining is thickened with a pale yellow/grey necrotic membrane adhering tightly to the submucosa.
• Clinical signs include persistent pasty-grey diarrhea, emaciation, and dehydration.
• Pathogenesis is caused by Clostridium perfringens type C (and type A).
• Bacteria attach to enterocytes and produce toxins. Necrosis and diarrhea result. Increased vascular permeability and toxaemia occur.
• Diagnosis involves detecting beta-toxins in feces, culturing, or genotyping methods. Histological appearance shows segmental hemorrhagic necrosis, effecting the entire mucosa. Thick bacilli with square ends are within the necrotic villi. Rod-shaped bacteria within intestinal lumen and mucosal impression smears are visible.

Porcine Epidemic Diarrhea

• Dilated small intestine showing diffuse, acute, fibrinonecrotic enteritis.
• Fluid is clear serous and full of gas.
• Intestinal wall is thinner.
• Clinical signs include diarrhea, dehydration, vomiting, fever, anorexia.
• Pathogenesis is associated with coronavirus (notifiable) or rotavirus (not notifiable).
• Viruses replicate in villi, causing fusion and atrophy and resulting in malabsorption and osmotic diarrhea.
• Dehydration, metabolic acidosis, and eventual death can occur.
• Diagnosis uses fecal testing.

Enteric Coccidiosis

• Small intestine shows diffuse, acute, fibrinonecrotic enteritis.
• Fibrin (yellow, membranous) is easily detachable from the mucosa.
• Clinical signs include diarrhea and emaciation.
• Pathogenesis involves cytoisospora suis infecting enterocytes causing fusion, atrophy, and subsequent necrosis.
• A significant pre-patent period is only 5 days.
• Diagnosis involves fecal testing.

Bronchopneumonia

• Presents as cranioventral reddening.
• Tissue is firm and shows suppurative bronchopneumonia.
• Mild interstitial edema is present.
• Clinical signs include difficulty breathing, fever, reddened skin, and increased respiration.
• Pathogenesis is linked to inhalation of bacteria like Pasteurella multocida and Bordetella bronchiseptica.
• Toxins are produced, leading to inflammation and tissue damage.
• Diagnosis involves bacteriology culture.

Septicaemia

• Characterized by multifocal petechial hemorrhage and fibrinous peritonitis.
• Clinical signs include sudden death, fever, rapid breathing, and congested/cyanotic extremities.
• Pathogenesis involves Klebsiella pneumoniae subspecies.
• Bacteria disseminate through the bloodstream causing toxic effects and vascular damage leading to edema, effusions into body cavities and widespread hemorrhage.
• Diagnosis involves bacteriology using swabs from various organs.

Porcine Proliferative Enteropathy

• Diffuse proliferative enteritis of the ileum.
• Subclinical disease.
• Ileum shows subclinical wasting.
• Diarrhea is common, and, in some cases, intestinal perforation can occur.
• Clinical signs include wasting, prolonged diarrhea.
• Pathogenesis involves Lawsonia intracellularis affecting the ileum and producing diffuse proliferative enteritis. The bacteria replicate within enterocytes, leading to hyperplasia and hypertrophy of the intestinal mucosa, mucosal necrosis and hemorrhage. Diagnosis can involve Warthin-Starry silver stains.

Swine Dysentery

• Mucoheamorrhagic and fibrinonecrotic colitis is observed.
• Clinical signs include subclinical-peracute course with fever, bloody/mucous diarrhea, wasting, breathing difficulties, and drowsiness.
• Pathogenesis is caused by bradyspira brachyspira hyodysenteriae. This causes intestinal mucous disruption with subsequent toxins leading to damage and inflammation.
• Diagnosis includes histopathology with silver stain (Warthin-Starry), along with PCR and anaerobe culture.

Postweaning Multisystemic Wasting Syndrome (PMWS)

• Characterized by polyserositis, petechiae, nephritis, and pneumonia.
• Clinical signs include wasting, poor body control, impaired growth.
• A variety of pathogens are implicated.
• PMWS is an immunosuppressive disease of growing pigs.
• Diagnosis includes bacteriological culture and/or PCR, particularly from lung tissue.

Contagious Pneumonia

• Multifocal consolidation (appearance in water/formalin solution).
• Clinical signs include fever, conjunctivitis, ear/snout discolouration, respiratory distress, anorexia and weight loss.
• Pathogens leading to pneumonia include Actinobacillus pleuropneumoniae.
• Diagnosis involves a histological analysis of lung tissue along with culturing and PCR tests. Confirming pathogens by IHC/PCR from lung and lymphoid tissue is imperative, as are appropriate cultures.

Postweaning Multisystemic Wasting Syndrome (PMWS)

• Similar to septicaemia in pre-weaned piglets.
• Polyserositis.
• Clinical signs include wasting, poor body control and reduced growth.
• Pathogenesis is caused by porcine circovirus type 2 (PCV-2).
• Diagnosis involves bacteriological culture + PCR to confirm diagnosis.

This quiz explores key characteristics and clinical signs of enteric colibacillosis and enteric clostridiosis in animals. You'll learn about the pathological features, diagnostic methods, and the role of pathogenic bacteria in these diseases. Test your understanding of these important veterinary conditions.