what are the 4 MAJOR HINTS that you are probably looking at colitis on your bloodwork?
Neutropenia with left shift, Hypoproteinemia (inflamed wall), metabolic acidosis (bc hyperlactatemia), Hyponatremia
what will colitis look like on the CBC?
Increased PCV, Neutropenia with left shift (bc acute-- not that many neutrophils avail, and all young neutrophils ), Hypoproteinemia (inflamed colon wall), Hyperlactatemia (poor perfusion)--> metabolic acidosis
(1) Laminitis (bc endotoxemia) (2) Thrombophlebitis (bc gonna be using catheters) (3) Coagulopathy (prolly something to do with inflammatory factors)
Treatment of Acute Colitis?
Discontinue current antibiotic treatment! Then start Metronidazole, as well as Additional supportive care (fluid therapy) and Prophylaxis therapy for laminitis (cryotherapy), an NSAIDs, plasma, Polymixin B (to tx for possible endotoxemia)
how does the enterotoxin of salmonella affect the GI?
causes Secretory component through cAMP
what might bloodwork look like with a salmonella infection?
severe neutroPENIA (remember this is acute so the WBCs all go to that site and arent in the blood)
what is the fastest and most sensitive way to dx salmonella?
PCR of the feces
what must you keep in mind if you want to do a fecal culture for salmonella? Or testing the feces in general?
(remember that PCR is the fastest and most sensitive way) Need to take >5 samples taken 24h apart or 3 PCRs negative (increases sensitivity) (so to be sure have neg or pos horse, need to take mult samples if you wanna do a culture. if first few samples neg, doesnt mean horse is neg, bc not always excreted. so at least 5 samples 24hr apart and THEN thats neg then you can exclude salmonella )
what is a Nosocomial infection? Who is most at risk for this? Implications?
aka infection you get in a (veterinary) hospital. Salmonella most common in horses and presents a huge biosecurity risk: isolation!
what are some risk factors for the horse to develop salmonellosis?
stress, hospitalization, diet change, sx, general anesthesia, antimicrobial use, small colon impactions
what are the two sp of clostridium which usually affect horses?
Clostridium perfringens / difficile
what kinda organisms are Clostridium perfringens / difficile? Where are they usually found?
Gram + spore-forming anaerobe. Part of normal intestinal flora / ubiquitous in environment
If clostridium are normal flora, why are they causing problems?
Take advantage of an imbalanced gut: overgrow & colonize (imbalance usually from stress, immunosuppression, or ABX therapy which alter normal flora.)
what is the main thing clostridium sp do to cause acute diarrhea?
(perfringens and difficile) Produce toxins--> hypersecretory diarrhea
what kinda diarrhea is caused by clostridium?
which kinda diarrhea is caused by salmonella?
so if clostridium is always around in the gut, how do we know if the clostridium is causing the problem, or if it is something else?
try to detect the TOXINS which are causing the problem which are produced by the clostridium
what is happening in Antimicrobial associated diarrhea?
Antimicrobials can disrupt the normal intestinal flora
please don't forget where diarrhea comes from in horses
colon not sm int
what are the antimicrobials most associated with colitis in adult horses? (and what routes?)
(1) MACROLIDES: Erythromycin / Azythromycin / Clarithromycin po (famous for causing diarrhea in horses). (2) TMPS po (3) Ceftiofur iv (4) Oxytetracycline / Doxycycline (5) Neomycin………
what is interesting about the distribution of what drugs cause Antimicrobial associated diarrhea?
There is a wide and distinct geographic distribution of what drugs cause a problem
what two PE findings might give you an indication its clostridium thats causing the acute diarrhea?
Sight & smell
do you want to culture clostridium as a possible cause of diarrhea?
eehhhh... Difficult and time consuming, Presence of bacteria is only suspect for cause of disease (they are normal flora!)
how can you Identify toxins from clostridium in the feces? (2 ways)
(1) ELISA for enterotoxin A (so test directly) (2) PCR for genes that induce toxin A&B (test indirectly for genes)
what causes Potomac Horse Fever and how do horses get it?
caused by Neorickettsia risticii an obligate intracellular bacterium. Carried by flukes that infect aquatic insects: usually affects horses grazing near fresh water during warm seasons
what is early versus late dz like for potomac horse fever?
(1) Early dz: Infects and lives in monocytes. Causes morphologic damage in LI due to Mononuclear infiltration in lamina propria . (2) LATE dz: Fibrinous necrotizing typhlocolitis --> Severe mucosal ulceration
what is a common sequelae to PHF?
neorickettsia risticii first goes into ____ to do ___ to the GI, and then eventually _________ happens
in early dz infects monocytes---> infiltrates lamina propria. Then eventually there is Fibrinous necrotizing typhlocolitis--> severe mucosal ulceration
what are the clinical signs you can see with PHF?
Infections may be subclinical!! You can see: Diarrhea 60% cases, Laminitis 30% cases, Abortion syndrome
what are three ways to dx PHF?
(1) Presumptive in endemic areas (areas surrounding the Potomac River northwest of Washington, D.C) (2) serology (3) PCR ( (4) culture is possible but difficult)
which things get digested where in the equine GI tract?
In essence, grain overload is because of ... (explain pathophys)
Inappropriate pre-cecal digestion: They eat a BUNCH of grain, so then Not enough amylase production in SI to break it all down, so Too much CHO passed to cecum--> Proliferation of certain microflora populations--> those microflora create products which dec cecal pH--> Altered pH impairs normal microflora!!!!
what are the microflora that really like grain, and what are their products which drop the pH of the cecum?
MICROFLORA: Bacillus / Lactobacillus / Streptococcus. PRODUCTS: Lactate / Proprionate---> these drop the pH and impair normal flora from working, making a vicious cycle
what is the end results of grain overload?
(bc of drop in pH) Decreased fermentation, Cecal / colonic dysmotility --> gas distention, Colic pain + laminitis
what are the clinical signs of grain overload?
Colic, Gas distention / bloat, GI ileus, Endotoxemia, diarrhea
what can you do to tx grain overload in the early stages? later stages?
If early enough, gastric lavage. Otherwise, Mineral oil / charcoal (via NGT), Anti-endotoxemic therapy, ***** Laminitis prophylaxis, Severe gas distention may lead to dyspnea, in which case Cecal trocharization may be performed
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