Cows: Salmonella & Winter Dysentery

A set of flashcards focused on key concepts related to infectious gastrointestinal diseases in cattle, particularly Salmonellosis and Winter Dysentery.

What family does Salmonellosis belong to?

Family Enterobacteriaceae

How many serotypes of Salmonella are there?

There are 2200 serotypes based on O and H antigen groups.

What are the common serotypes of Salmonella that cause disease in cattle?

Salmonella Dublin, Salmonella Cerro, Salmonella Newport, Salmonella Montevideo, Salmonella Kentucky, Salmonella Typhimurium.

What is the transmission route for Salmonellosis?

Fecal-oral transmission, direct and indirect contact, contaminated environment, airborne, animal to animal

What are the types of carriers for Salmonella?

Active carrier, latent carrier, and passive carrier.

Pathogenesis of salmonellosis

Penetrates into ocular, nasal, oral, & intestinal membranes → S. dublin Invades through intestinal wall of ileum & cecum → infects mesenteric lymph nodes 

• factors affecting type of disease: immune status, age, stress, virulence 

• adhesion pilli, flagella, cytotoxins, enterotoxins, LPS, inflammatory response 

Virulence plasmid causes macrophage dysfunction → systemic infection

General clinical signs of salmonella

• Septicemia

• Acute enteritis

• Chronic enteritis

• Terminal dry gangrene of the extremities

• Abortion

What clinical signs are associated with septicemia in calves related to Salmonellosis?

Depression, toxemia, fever, dyspnea, weakness, nervous signs(incoordination, nystagmus), diarrhea.

What is a significant clinical sign of acute enteritis in older calves and adults with salmonellosis?

Acute protein losing enteropathy

• Abortions

• Polyarthritis (calves)

• Diarrhea

• Agalactia

• Abdominal pain → rolling, kicking, crouching, groaning, flank watching

What are the clinical signs from Chronic enteritis with salmonellosis? 

• inappetence

• reduced weight gain

• unthrifitiness   

What serovar causes abortion?

S. dublin

What laboratory findings are indicative of Salmonellosis?

• CBC may show leukopenia, neutropenia, severe degenerative left shift

• Biochem marked hyponatremia, mild hypokalemia (not eating anymore), hypoproteinemia (they are losing a lot)

How do we treat salmonellosis?

• antimicrobials → only for septicemia  

• fluids

• electrolytes 

• NSAIDs → only if animal is in pain because it delays mucosal healing 

What types of vaccines are available for controlling Salmonella in cattle?

Killed and modified live vaccines.

What is the main cause of Winter Dysentery in cattle?

Bovine coronavirus → Tropism for intestinal & respiratory tract, common in northern climates 

• Morbidity: 30-59%

• Mortality <1 %

How is Winter Dysentery transmitted among cattle?

Fecal-oral route from infected or asymptomatic carriers → highly contagious

Pathogenesis of winter dysentery

Virus has tropism for GI and respiratory tract → Mild small intestinal enteritis → Respiratory disease & pneumonia → Destroys epithelial cells of colon crypts → Mechanism of voluminous watery diarrhea not clear → Inflammatory medicators may lead to hyper-secretion in the small intestine & large colon

What are clinical signs of Winter Dysentery?

3-7 days incubation → Explosive diarrhea 4-7 days, fever, decreased milk production, dehydration

• young animals have mild signs 

• nasolacrimal discharge and cough before GI signs

What diagnostic methods are used for identifying Winter Dysentery?

Electron microscopy, ELISA test, paired serology testing (8 weeks apart)

What are the necropsy lesions associated with fatal cases of Winter Dysentery?

Severe hemorrhage, hyperemia of colonic and cecal mucosa, frank blood in the lumen of large intestine, microscopically widespread necrosis with degeneration of large bowel epithelium 

What treatments are generally recommended for Winter Dysentery?

Supportive therapy, fluids, and electrolytes

DDx for winter dysentery

• BVDV - Mucosal disease

• Coccidiosis

• Salmonellosis

• Johne’s disease

• Dietary

• Copper deficiency

DDx for Salmonellosis

Acute enteric form

Septicemic form

Chronic form