18. large animal med- acute diarrhea in adult cattle

what is the difference between cows ('mountain ruminants') and sheep/goats ('desert ruminants')?

main difference is the spiral colon, which has much fewer loops and less capacity to absorb water in cattle

what is the difference between the feces of cattle and sheep/goats?

cattle feces are normally soft (75-85% water in cattle, 55% water in sheep/goats)

increased water load to the large intestine is poorly handled

what is osmotic diarrhea?

increased delivery of solutes to the large intestine resulting in diarrhea

what are 2 causes of osmotic diarrhea in cattle?

1. gastric maldigestion

2. grain overload

how does gastric maldigestion lead to osmotic diarrhea in cattle?

any disruption of gastric fermentative or acid digestion of food leads to delivery of large, poorly digestible feed particles to the colon

these particles then draw in water to the colon

what are causes of gastric maldigestion leading to osmotic diarrhea in cattle?

DA

feed change

period of anorexia

oral medications

rumen acidosis

ulcers

how is gastric maldigestion diagnosed?

-knowledge of concurrent condition

-cow is otherwise bright

-normal labwork

-undigested large feed particles (corn) in feces

-this diarrhea is rarely profuse

what is the treatment for gastric maldigestion?

none- correct other conditions, transfaunation

how can grain overload lead to osmotic diarrhea?

cattle which survive peracute rumen acidosis have increased delivery of poorly absorbed lactate (especially D-form) to the intestine

also, changes in rumen flora and pH alter rumination frequency and inhibit digestion of large particles

when is osmotic diarrhea due to grain overload typically seen?

diarrhea seen 1-2 days after acute event

how is grain overload causing osmotic diarrhea diagnosed?

rumen or blood pH, knowledge of exposure to high energy feed

what is the treatment for grain overload causing osmotic diarrhea?

-correct rumen pH (usually too late tho)

-transfaunation

-maintain systemic electrolyte and acid-base balance

what are the most common causes of infectious diarrhea in cattle? (8)

1. salmonella

2. bovine viral diarrhea (BVDV)

3. winter dysentery

4. rinderpest (eliminated)

5. malignant catarrhal fever

6. schmallenberg virus

7. eimeria

8. adenovirus

A Sad Bovine Wins Really Malignant, Effusive, S***

what are the 2 main diseases of bovine viral diarrhea virus (BVDV)?

1. acute BVD

2. mucosal disease

what is acute BVD?

infection of an immunocompetent cow with either cytopathic or non-cytopathic strains

how is acute BVD transmitted?

primarily thru the respiratory system, where it gains access to the blood (first fever w/ viremia) and carried to other susceptible tissues

which animals are susceptible to acute BVD?

all ages are susceptible, but vaccinated cattle and calves with good colostral antibody have better protection

can occur as individual cases or outbreaks depending on immunity

what lesions are seen with acute BVD?

virus multiplies in and kills epithelial cells and other cells:

-WBCs: neutropenia and necrosis of peyer's patches

-epithelium: GI ulcers, necrosis of crypt cells

affects GIT from mouth to colon, nasal and ocular mucosa, coronary band, resp. tract in some cases

what are the clinical signs of acute BVD?

-depression

-anorexia (decreased production)

-high biphasic fever

-panleukopenia

-diarrhea

-oculonasal discharge

how is acute BVD diagnosed?

-isolation,

-PCR

-FA of virus from blood, secretions, tissues (not feces)

-rising antibody titer (serum neutralization)

how is acute BVD treated?

supportive care

how is acute BVD prevented?

vaccination (reduces morbidity and mortality)

2-shot series is necessary to initiate immunity, esp. against severe type-2 strains, and annual boosters recommended to enhance colostral protection

what may decrease BVD vaccine efficacy?

antigenic diversity

what 2 vaccines are available for BVD?

1. modified live vaccines: give better immunity with one shot, but cause immunosuppression and viral replication

2. killed vaccines: do not cause immunosuppression, but protection is short lived (3-4 months)

what animals can modified live vaccines of BVD be used for? which animals should they not be used for?

modified lives BVD vx's are good for calves (6 months old) or synchronized herds (pre-bred beef cattle)

do not use on or near pregnant cows

which animals are killed BVD vaccines good for?

safe for pregnant cows

also herds with constant calving (dairies)

what is BVD-mucosal disease?

infection of a persistently-infected cow with a cytopathic strain or mutation of a non-cytopathic strain to cytopathic

what are the clinical signs of BVD-mucosal disease?

looks like acute BVD but often has more severe coronary band, eye, and mouth lesions (blunted papillae)

how is BVD-mucosal disease diagnosed?

-virus isolation

-FA/IHC from blood, secretion, tissues (ear notch)

how is BVD-mucosal disease prevented?

prevention of carrier state: good immunity of dams, prevention of infection/live virus vaccination during pregnancy

identification and culling of PI animals (virus isolation, IHC)

what causes winter dysentery?

enteric coronavirus

-potentially same strains as affected calves

-low titers in adults appear to increase susceptibility, as does using same equipment to provide feed and remove manure

-may spread thru respiratory tract

what lesions are seen with winter dysentery?

coronavirus kills villus tip cells in most of the small and large intestine, resulting in shortened and clubbed villi and malabsorption/maldigestion

what are the clinical signs of winter dysentery?

-profuse, acute watery diarrhea, often with frank blood

- +/- recent history of respiratory disease

-fever occurs very early or not at all

-often occurs in outbreaks in cattle housed for winter

-high morbidity, low mortality

what is the treatment for winter dysentery?

self-limiting (days for cow/weeks for herd)

-fluids for severely affected cows

how is winter dysentery diagnosed?

-electron microscopy of feces

-rising antibody titer (for coronavirus)--> Ag-capture, ELISA, PCR

what is the morbidity/mortality of rinderpest?

extremely contagious, high morbidity and high mortality

what diseases does rinderpest appear similar to?

acute BVD, MCF

what is the cause of malignant catarrhal fever (MCF)?

sheep associated and wildebeast associated caused by ovine herpesvirus-2 and alcelaphine herpesvirus-1 and 2

cattle, bison, and other exotics get dz from asymptomatic sheep, usually around lambing time

what lesions are seen with malignant catarrhal fever?

cytotoxic t-cell mediated vasculitis of most epithelial surfaces

what are the clinical signs of malignant catarrhal fever?

-crusting oral and nasal ulcers

-conjunctivitis with corneal edema

-high fever

-diarrhea

-hematuria

-coronitis

-encephalitis

-lymphadenopathy

what is the treatment for MCF?

symptomatic

but most affected animals die within 96 hours

what causes schmallenberg virus?

single stranded RNA orthobunyavirus of the Simbu serogroup

only seen in western europe

what are the clinical signs of schmallenberg virus?

acute clinical signs are rare/mild. more important is the generation of birth defects in the fetus or pregnant hosts:

-pregnant hosts: fever, diarrhea, drop in milk production, abortion

-birth defects: arthrogryposis, hydranencephaly, brachygnathia inferior, ankylosis, torticollis, scoliosis

what is the treatment for schmallenberg virus?

none, symptomatic

adults recover in 2-3 weeks

how is schmallenberg virus controlled?

vector control (culicoides), there is no vaccine

what are clinical signs of adenovirus in cattle?

severe diarrhea and depression, progressing to recumbency and death

what lesions are seen with adenovirus in cattle?

on necropsy: congested and edematous gut with hemorrhagic contents

basophilic intranuclear inclusion bodies may be found in vascular endothelium and infected gut, and often in kidneys

what are 4 potential causes of toxic diarrhea in cattle?

1. endotoxemia

2. arsenic poisoning

3. plant poisonings

4. blister beetles

Each Bovine Ate Plants

what are possible causes of diarrhea caused by endotoxemia in cows?

coliform mastitis, toxic metritis

how severe is diarrhea caused by endotoxemia in cows?

mild, non-profuse diarrhea that resolves if/when the primary disease resolves

mimics salmonellosis, but endotoxemia usually has less severe diarrhea

what are causes/sources of arsenic poisoning in cattle?

-pesticides

-burned wood preservatives and paints (pressure treated lumber, arsenic concentrates in ash)

-medicines (insecticides)

-industrial products containing arsenic

how does arsenic cause pathology when ingested?

arsenic is directly irritating to the gut and when absorbed, inhibits oxidative phosphorylation, binds sulfur-containing amino acids

-affects metabolically active tissues

how does the body remove arsenic?

rapidly removed from the body thru urine, feces, and milk

what lesions are seen with arsenic poisoning?

gut, kidney, liver most commonly affected

-hemorrhagic gastroenteritis

-renal glomerular and tubular necrosis

-fatty liver

what are the clinical signs of arsenic poisoning in cattle?

-sudden death

-colic

-vomition

-fetid watery, hemorrhagic diarrhea

-GI perforation

-ataxia

-high morbidity/mortality

ingestion of what plants can lead to toxic diarrhea in cattle?

oak

yew

death camas

which plants do blister beetles most commonly affect?

alfalfa pastures

-but flowering weeds in or near any type of pastures can attract the beetles

what is the toxic principle of blister beetles?

cantharidin (a surface irritant): may cause hemorrhagic ulceration of the oral and esophageal mucosa, as well as the stomach and intestinal tract

what are clinical signs of blister beetle toxicity in cattle?

clinical signs relate to affected organs:

-dysphagia with quidding and (pseudo)ptyalism

-colic

-hemorrhagic diarrhea

-dysuria

-shock and death

what blood abnormalities may be seen with blister beetle toxicity?

-evidence of renal disease and/or shock

-hypoproteinemia

-hemoconcentration

what postmortem lesions are seen with blister beetle toxicities?

hemorrhagic, ulcerative lesions in affected GI or urinary organs

what is the treatment for blister beetle toxicity?

removal from feed source and supportive care against shock and secondary infections

what is cold cow syndrome?

acute diarrhea and ataxia in dairy cows given access to ryegrass pasture in early spring

what are clinical signs of cold cow syndrome?

-cows act drunk, wobbly, and may fall down

-cows are cold to the touch with normal rectal temperatures

-profuse, non-fetid diarrhea

-sudden, dramatic drop in milk production (up to 100%)

what is the treatment for cold cow syndrome?

remove from pasture and feed indoors for 24 hours; usually recover

how is cold cow syndrome prevented?

avoid certain pastures in early spring