Lecture 26 4/1/25 Flashcards by Danika Boltz

What is the relevant background info regarding cattle and fecal production?

-produce 30 to 50 kg of feces/day
-10 to 24 bowel movements/day
-ingesta passage takes 1.5 to 4 days

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What is the relevant background info regarding small ruminants and fecal production?

-spiral colon leads to pelleted feces
-appearance of “diarrhea” may not follow typical presentation; may be larger or more chunky

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What can cause a repugnant odor in ruminant feces?

-blood
-inflammatory products
-necrotic tissues

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What should be assessed on PE in all animals with diarrhea?

hydration status; look at medial canthus and determine eyeball recession

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Which diagnostics can be done on animals with diarrhea?

-bloodwork
-urinalysis
-abdominal ultrasound
-fecal float/cytology/culture

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What is important regarding mortality rate in adult ruminants with diarrhea?

mortality rates are low and disease will typically resolve within a few days

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What are potential nutritional causes of diarrhea in adult ruminants?

-simple indigestion
-ruminal acidosis
-copper deficiency

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What are the characteristics of Ostertagiasis?

-most common parasitic cause of diarrhea in adult ruminants
-protective immunity occurs in animals older than 2
-clinical disease occurs
-treatment/deworming should be focused on first season beef/dairy animals and older animals with decreased immunity

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What are the characteristics of winter dysentery?

-caused by bovine coronavirus
-acute
-highly contagious, high morbidity (100%)

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What are the concurrent risks for winter dysentery?

-seasonal and geographical
-dairy cattle
-diet changes
-cold temps
-poor ventilation

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How is winter dysentery transmitted?

-fecal-oral
-close contact
-fomites

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What is the pathophysiology of winter dysentery?

-viral replication in colonic crypt cells
-hypersecretion in small intestine and colon leads to voluminous diarrhea
-destruction of mucosal epithelium leads to transudation and hemorrhagic nature

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What are the clinical signs of winter dysentery?

-100% morbidity within 7 to 10 days
-explosive diarrhea
-severe depression of milk production
-variable anorexia
-variable depression
-variable coughing
-musty, sweet and fetid odor

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How is winter dysentery diagnosed?

-signs and features
-detection of BCoV within diseased system
-seroconversion

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What are the characteristics of winter dysentery treatment and prevention?

-treatment not typically needed; often spontaneous resolution unless a persistent diarrhea
-no available vaccine
-must focus on biosecurity

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What are the possible bacterial causes of diarrhea in adult ruminants?

-salmonellosis
-endotoxin-induced
-Johne’s disease

What are the characteristics of salmonellosis?

-Salmonella enterica subsp. enterica
-host-adapted strain is S. dublin type D
-dost adaptation allows for chronic, subclinical carriers
-zoonotic
-spectrum of clinical dz
-increasing prevalence, especially in large dairy herds

How is Salmonella transmitted?

-fecal-oral
-mammary gland shedding
-possibly carrier exposure

What is the pathogenesis of salmonellosis?

-ingested bacteria attach to mucosal cells and penetrate them (enteroinvasive)
-bacteria are engulfed by mononuclear cells and become facultative intracellular pathogens
-bacteria go to regional lymph nodes and can become latent
-maldigestion and malabsorption occur, causing clinical signs within 10 to 18 hours of infection

Which factors determine where an animal falls within the salmonellosis clinical disease spectrum?

-host immunity
-serovar/host adaptation
-exposure dose
-age

What are the clinical signs of salmonellosis?

-fever
-depression
-anorexia
-septicemia/shock
-bloody diarrhea with fibrin
-abortion between 5 to 9 months gestation

What are the characteristics of salmonellosis diagnosis, treatment, and control?

-diagnosed by finding the organism (feces, blood, BAL) or via S. dublin ELISA
-treated with antibiotics
-prevention via good management and vaccination

Which vaccines exist for salmonellosis?

-bacterins
-core-Ag
-siderophore recep and porin proteins

What are the characteristics of endotoxin-induced diarrhea?

-occurs in livestock with endotoxemic conditions
-mechanism poorly understood; involves prostaglandins and nitric oxide synthases
-low volume diarrhea

What are the characteristics of paratuberculosis/Johne's disease?

-caused by Mycobacterium avium subsp. paratuberculosis -chronic enteric dz of all ruminants -worldwide dist.

How is Johne's disease transmitted?

-fecal-oral -transplacental/mammary

What are the characteristics of Johne's disease resistance?

-genetic predisposition; some are more resistant than others -resistance comes with age; calves more susceptible than adults -any natural immunity can be overcome by a high enough dz burden

What are the characteristics of Johne's dz prevalence?

-much more commonly found in dairy cattle than beef cattle, small ruminants, and camelids -considered an iceberg dz; for every 1 clinically affected animal there are nearly 25 that are subclinically affected -concerns for zoonosis; has been found in Crohn's patients

What occurs within the intestinal tract when Mycobacterium enter?

-macrophages are exposed to MAP -mycolic acid on bacteria prevents destruction and bacteria enter macrophages -macrophages secrete cytokines and chemokines to elicit immune response -granulomatous inflammation of ileum and malabsorptive diarrhea occur

What is the pathophysiology of Johne's?

-M cells allow for "sampling" of bacteria -macrophages and Th1 response involved in early stage -eclipse phase involves asymptomatic shedders and Th2 response -late stage involves fulminant dz and mammary gland and transplacental spread

What is the incubation period for Johne's dz?

2 to 7 years, with an average of 2 to 4 years

What are the stages of Johne's dz?

Stage 1: silent; initial infection and proliferation phase Stage 2: eclipse; shedding but no clinical dz; difficult to detect Stage 3: clinical disease begins; positive on blood test Stage 4: severe granulomatous infection, maldigestion, PLE, and rapid deterioration

What are the clinical signs of Johne's dz?

*dose dependent -pipe stream diarrhea (chunky manure in SR and camelids) -bright, good appetites with continual loss of BCS -NO pyrexia -submandibular and brisket edema due to PLE and loss of oncotic pressure

Which test is used to screen for Johne's?

antibody detection via ELISA -low sensitivity, high specificity -serial testing can increase sensitivity

Which test is used to confirm Johne's?

fecal culture and PCR -sensitivity and specificity of 100%

What are the characteristics of Johne's dz treatment?

-animals are often culled due to risk to remaining population -may treat production animals, pregnant animals, and animals with genetic/emotional value

How is Johne's disease prevented/controlled?

*non-infected herds: -maintaining a closed herd and screening new additions *infected herds: -establishing objectives regarding eradication vs management -test and cull -prevent new infections with good hygiene in high risk exposure sites *vaccination: -requires approval from state vet due to cross-reactivity with TB test -adjuvant to management in high prevalence herd