Intestines, Enteritis, and Peritonitis

Enteritis in dogs: Ancylostoma caninum

Anemia and hypoproteinemia in puppies.

Bacteria enteritis: Salmonella

Animals that recover from infection can become carriers and shed the organism in feces. Horses and turtles are normal carriers. Zoonotic: Salmonella Typhimurium is the second most common food-bourne illness in humans.

Bacteria enteritis: Clostridium perfringens

Associated with a change in the enteric microbiota due to abrupt changes in the feed, abnormally nutrient rich feed, and antibiotic therapy. TOXINS: produces 4 major toxins. Confirmation of clostridial infections requires isolation of clostridial toxins because these pathogens are normal inhabitants of the intestinal flora.

Agents that cause necrotizing changes to enterocytes causing enteritis:

BVD virus Rhodococcus equi

How can Salmonella cause intussusception in horses?

Because salmonella causes hypermotility.

Hemomelasma ilei

Black to dark red, raised areas in the serosa of the intestine of horses, most commonly seen in the ileum sue to scratches from Strongyles causing hemorrhage.

Agents that cause inflammatory changes to enterocytes causing enteritis:

Boxer colitis Johne's disease Amyloidosis Lymphoma

Intussuscipiens

External segment.

Peritonitis in cats: Feline Infectious Peritonitis (FIP)

FIP coronavirus is a mutation of the feline enteric coronavirus. Dry vs. Wet

Coccidiosis in swine

Fibrinonecrotic enteritis. Leakage of vessels > fibrin

Peritonitis in pigs: Trueperella pyogenes E. Coli

Fibrinosuppurative peritonitis

Peritonitis in calves: Salmonella

Fibrinous peritonitis

Enteritis in dogs: Heterobilharzia americana

Fluke that causes hypercalcemia > mineralization.

Most important cause of diarrhea in calves?

Escherichia coli. Enerotoxigenic - non inflammatory Enteropathogenic - destroy microvilli Enterohemorrhagic - verotoxin, erosive fibrinohemorrhagic enterocolitis. Food-bourne pathogen for humans. Bovine can be carriers of O157:H7 found in ground beef.

Enteritis in Ruminants: Oesophagostomum

Parasitic granulomas in wall of intestines. Can result in intussuception.

Obstructions and impactions: Fat necrosis in cattle

Partially occludes the GI lumen

Enteritis in cats: Feline Panleukopenia

Parvovirus in kittens. Intrauterine infection can result in congenital cerebellar hypoplasia in kittens.

Enteritis in Ruminants: Bovine viral diarrhea

Pestivirus causing necrosis of pyer's patch (like parvo virus in dogs).

Chronic enteric salmonellosis

Pigs. Necrosiss and ulceration in cecum and colon. Button ulcers.

Enteritis in pigs: Lawsonia intracellularis

Porcine proliferative ileitis in pigs older than 4 months. Intracellular Lawsonia bacteria induce hyperplasia of crypt epithelium. Like Johne's dz in ruminants but this is diffuse.

Most common site for volvulus to occur in horses.

Left colon and the twist is most commonly clockwise around the mesocolon. Mares torsions often occur in the peripartum period.

Intestinal causes of Diarrhea

Malabsorption in small intestine. Bacterial toxins that stimulate cAMP > shuts down Na/Cl cotransport > Cl and water hypersecretion Increased epithelial permeability. Hypermotility.

Intestinal neoplasia: Intestinal adenocarcinoma

Malignant glandular epithelial tumor

Intestinal neoplasia: Lymphoma

Malignant tumor mesenteric lymph nodes.

Congenital colonic aganglionosis

Megacolon from absence of myoenteric or submucosal neurons in colon and rectum. Overo foals predisposed.

M cells

Microfold (M) cells - epithelium that covers pyer's patches. Participate in uptake of protein and peptide antigens from intestinal lumen and transport them to the GALT.

Protein Loosing Enteropathy: Lymphangiectasis

Most common cause of PLE in dogs. Disease effecting the lymphatics, or acquired due to lymphatic obstruction from granulomatous or neoplastic disease. Problems: hypoalbuminemina and hypoglobulinemia

Post-mortem intussusception

Mucosa and serosa of the affected segments have normal color.

Can you grossly differentiate enteritis from salmonella and clostridium?

NOPE

Atresia Ani

No anus

Tiger stipping

Non specific congestion in the colon due to diarrhea and tenesmus (straining to defecate)

Consequences of Diarrhea

Dehydration > hypovolemia > hemoconcentration > inadequate tissue perfusion > anaerobic glycolysis > KETOACIDOSIS > bicarbonate loss in diarrhea > inadequate renal perfusion > increased intracellular H+ and decreased K+ > decreased myocardial contraction > hypovolemic shock

Meckel's diverticulum

Derived from the omphalomesenteric duct (yolk sac). Usually incidental finding.

Enteritis in dogs: Salmon Poisoning

Dog ingests salmon carrying the fluke Nanophyetus salmincola which harbors Neorickettsia helminthoeca. Necrosis and hemorrhage of peyer's patches.

Agents that cause damage to microvilli and glycocalyx causesing enteritis:

E. coli Lactose intolerance (lack of lactase in glycocalyx)

Enteric colibacillosis

E. coli (ETEC) in neonatal pigs <1 week old.

Edema Disease

E. coli verotoxin causing vascular damage leading to edema. ONLY in weaned pigs.

Enteritis in Horses: Cyathostomiasis (small strongyles)

Each nodule is a parasite growing inside of the mucosa. Strongyles may infiltrate the wall of the cranial mesenteric a. resulting in endarteritis and thrombosis resulting in vascular occlusion and bowel infarction.

Viral enteritis: Coronavirus

Enteritis is more prolonged than that seen with Rotavirus. Results in hyperplasia and necrosis of crypt cells and inflammation in the lamina propria. Calves and cats.

Epiploic Foramen Entrapment in horses

Internal herniation when loops of intestine are displaced in the foramen that separates the omental bursa from the peritoneal cavity.

Agents that cause vascular changes to enterocytes causing enteritis:

Johne's disease Lymphoma Endotoxemia

Peritonitis in horses: Rhodococcus equi

Suppurative peritonitis

Protein Loosing Enteropathy Chronic inflammation

TNF-alpha causes increased paracellular permeability of large molecules entering the mucosa, allowing plasma protein to enter the lumen. Problems: hypoalbuminemina and hypoglobulinemia

Bacteria enteritis: Escherichia coli

Temperature extremes, crowding and co-infections predispose young pigs and calves to develop these disease. Colonization and adhesion result in metabolic dysfunction or death of enterocytes. Bacteria can invade the vasculature causing spticemia. Toxins: Labile toxin, stable toxin A and B (hypersecretion) Vertotoxin: vascular endothelial injury causing edema disease.

Non intestinal causes of diarrhea

Thyroid hyperplasia Addisons Chronic renal disease Pancreatic insufficiency.

Intussusceptum

Trapped segment.

Volvulus and torsion

Twisting and rotation of intestines. Results in vascular obstruction, compromise and ischemia, followed by infarction of the affected segment.

Inflammation of the cecum

Typhlitis

Inflammation of the cecum and colon

Typhlocolitis

External herniation: Ventral hernia

Ventral hernia of the abdominal wall post-op wound dehiscence.

Intussusception

When one segment of the intestine invaginated into another section of intestine.

Enteritis in Horses: Rhodococcus equi

Young foals with lung infection > penetrates cells and survives in macrophages (like mycobacterium) > pyogranulomatous lumphasdenitis in lungs and large intestine lymph nodes.

2 most common clostridial infection in horses?

C. perfringens or C. difficile.

Paracute salmonella speticemia

Calves, foals, and pigs. Salmonella Cholerasuis - causes vasculitis, cyanosis of extremities and fibrinous polyserositis.

Acute enteric salmonellosis

Cattle, pigs and horses. Salmonella Typhimurium - catarrhal ileotyphlicolitis. Septic tank smell.

Enteritis in Ruminants: Johne's disease

Caused by Mycobacterium avium paratuberculosis (survives inside macrophages). Granulomatous inflammation response in lamina propria resulting in malabsorption. Cerebriform appearance to mucosa on necropsy.

Enteritis in pigs: Swine dysentery

Caused my Brachyspira hyodysenteriae. Toxin causes necrohemorrhagic diarrhea.

Clostridium perfringens Type D

Causes enterotoxemia associated with grain overload and sudden change in diet > PULPY KIDNEY in sheep.

Enteritis in dogs: Trichuris vulpis

Causes hemorrhagic typhlocolitis (cecum and colon) with bloody diarrhea.

Enteritis of dogs and cats: Inflammatory Bowel Disease

Causes malabsorption and chronic protein loosing enteropathy. Disease of exclusion. All other possible causes of gastroenteritis have to be ruled out before diagnosis with IBD.

Enteritis in dogs: Toxocara canis

Chronic diarrhea and weight loss.

Canine Hemorrhagic Gatroenteritis

Clostridium perfringens overgrowth in dogs.

Inflammation of the colon

Colitis

Enteritis in pigs: Porcine epidemic diarrhea

Coronavirus. Pigs all age groups causing a watery diarrhea. Outbreak in USA in 2013 with >50% morbidity.

Enteritis in pigs: Transmissible gastroenteritis

Coronavirus. Pigs up to 10 days. Virus targets the villi causing disease more severe than rotavirus.

Cryptosporidium

Found in GI, biliary, and respiratory tract of mammals, birds, reptiles and fish causing microvilli atrophy (very superficial dz). Zoonotic disease in immunocompromised people.

Peritonitis in pigs: Haemophilus parasuis

Glasser's disease.

Goblet, Paneth and enterocromaphin cells

Goblet cells - secrete mucus Paneth cells - produce toxins that kill bacteria and protect the proliferating cells from infection. Enterochromaffin - produce serotonin, gastin, somatostatin, CCK etc.

GALT

Gut associated lymphoid tissue. Pyer's patch (picture)

Coccidiosis in cattle

Hemorragic enteritis.

Clostridium perfringens Type C

Hemorrhagic and necrotizing enteritis.

Coccidiosis in sheep and goats

Proliferative enteritis.

Agents that cause damage to crypt cells causesing enteritis: target rapidly dividing cells.

Radiomimetic agents Parvovirus BVD virus Rinderpest virus Mycotoxins

Viral enteritis: Rotavirus

Results in dehydration and yellow, watery diarrhea. Degeneration and loss of enterocytes. Virus produces enterotoxin (NSP4) that increases Cl secretion and block the Na/glucose cotransporter. Calves and piglets.

Agents that cause damage to absorptive enterocytes causesing enteritis:

Rotovirus Coronavirus Brachyspira hyodysenteriae Coccidia Criptosporidia

Enteritis in dogs: Canine parvovirus type 2

Seen in puppies causing necrohemorrhagic enteritis with necrosis of Peyer's patches.

Enteritis in dogs and cats caused by fungus: Histoplasma

Severe granulomatous enterocolitis and lymphadenomegaly. Lots of organisms in macrophages (picture).

Obstructions and impactions: Foreign bodies in cats

Skirt like appearance of intestines with linear foreign bodies in cats.

Obstructions and impactions: Impaction in horses

Small intestinal impaction due to large numbers of ascarids. Colon impaction due to sand accumulation in colon.

External herniation: Umbilical hernia

caused by a defect in the abdominal wall.