---start----
donawick
medsurg3
11/10

having decided that a horse may 
have a life threatening lesion, we now need to provide care:

-relieve 
distension of stomach
-give analgesics
-give broad spectrum antibiotics

-administer polyionic solution IV
-give bicarb or a bicarb precursor IV.


assume metabolic acidosis until proven otherwise, because that happens 
unless there is a really high obstruction.

relief of gastric distension:


pass nasogastric tube as part of your first stage of management. the 
horse can't vomit like other animals can, so when stomach fills it can 
rupture. the stomach is small. it can only hold about 3 gallons. fluid 
can back up through pyloric sphincter, from the intestine, and overfill 
the stomach. so deflating the stomach protects against rupture, and 
removes distension. so it also reduces pain. sometimes we pull off liters 
of stuff this way. that means we're probably also getting stuff from the 
intestine via a distended pylorus also. 
This is also diagnostic - it 
giives you a clue that there may be a high obstruction.

slide: horse 
with NG tube in place. some referring vets do not want to leave the tube 
in place but often they will do that for us and leave it in during 
transport. this keeps esophageal sphincter open so fluid can come out 
through tube or around tube.

gastric rupture can happen and it is really 
hard to fix that. here's a slide where local vet didn't pass nasogastric 
tube, and the stomach ruptured right when it got here. when the stomach 
ruptures, the pain goes away, by the way. he's in horrible pain before 
the rupture, then suddenly looks much better. but that's bad. these 
horses die within 30 minutes - an acute, violent death - they flip right 
over backwards, and we do not really know why they do that but they do. 
they are dead when they land. don't stand behind them!

Do give 
sufficient analgesics: there are two - one is xylazine (Rompun) and the 
other is detomidine - those are the best two we've decided on. We usually 
use xylazine first when we're not sure if case is life threatening - it 
has a shorter length of action than detomidine, and does not have the 
degree of suppression of pain that detomidine has, but is a good start. 
what's the dose? well, 300 mg IV is a good dose to try to see what 
happens. Does banamine have a place? Flunixin meglumine, that is? he'll 
get to that in a minute. there is no reason today to walk a horse for 
hours like people talk about. we have drugs to take away the pain and 
prevent the horse from rolling around. so we don't have to walk him to 
keep from rolling. just sedate him. then we can wait and see if he gets 
better or not. detomidine is used when the pain is violent, 
uncontrollable. go up to 10 mg (1 mL) IV - lasts longer, suppresses more 
pain, and can be confusing if the referring vet uses it, because horse 
will look good when it gets here or to the specialist b/c you can't tell 
progression. here at NBC, if we've decided to do surgery, then we'll give 
the detomidine.  regarding flunixin meglumine, the problem is the 
duration of effect is up to 12 hrs. this is even worse than the 
detomidine. it is less effective as an analgesic, but it lasts longer, so 
if you give it early, horse looks better, and you delay making your 
decision, and you lose precious time because you have this false sense of 
security that things are better. if you are sure you have a 
nonlifethreatening lesion such as impaction of large colon, and you know 
you aren't going to operate, and the horse has recurrent moderate pain, 
then sure, you can use flunixin meglumine, it would then be a good 
choice. but on the board exam, the answer to "what drug do you not use to 
control colic in the horse" might be "flunixin meglumine" :)

Initial 
control of pain: xylazine 100-300 mg IV; xylazine 100 mg and flunixin 
meglumine 300 mg IV; for uncontrolled pain -- 10 mg detomidine IV.

Do 
give a broad spectrum antibiotic: since you do not know what it is, and 
you suspect there may be vascular compromise with death of bowel and 
leakage of contents or migration of bacteria into blood, you want to try 
to protect the horse with antimicrobials as best as you can. you need to 
get gram pos and neg and anaerobes. so, aminoglycosides like amikacin, 
gentomicin, may delay the onset of septic shock and improve survival. of 
course, three years from now we may have different drugs. probably what 
you will do today is use penicillin plus an aminoglycoside. gentamicin 
isn't the best choice anymore. amikacin is better. there is too much 
gentamicin resistance these days. now, once you start using the drugs - 
you dno't have to keep using them forever. if you open the horse and find 
only a mechanical obstruction and there is no contamination, you can d/c 
abx. 

Do administer fluids: 
give them IV.
PO or per tube ok only if 
there is no gastric reflux, no abdominal distension, no strangulating 
lesion. you need to be sure the GI tract is intact. like, if horse has an 
impaction, you could give fluids per tube. the impaction is b/c ingesta 
is dried out and stuck. so pour water in. not more than 3 gallons b/c the 
stomach isn't bigger than that. so you can give 2 gallons. normal transit 
time in horse for water from stomach to cecum is 15-30 minutes. thank 
you, Kirsten.

slide: poodle sitting on top of a horse. 

there is a 
difference b/w these two animals. the reason large animal vets are so 
superior to small animal veterinarians is the difference in size.  :)

when a large animal vet must give fluids to a horse, you need to give 
bathtubs full of fluids. liters and liters. if a 500 kg horse is 10% 
dehydrated, that's 50 liters it needs. if the 5 lb dog (2.5 kg) dog is 
10% dehydrated, it only needs a little bit of fluid :)
think in terms of 
bathrubs.give a balanced salt solution that mimics plasma as far as the 
electrolytes go. 140 mEq Na+. 100 mEq Cl-. Saline solution doesn't have 
that balance. K+ about 4 mEq/L. Abbot and Baxter make fluids that match 
this - Normosol-R comes in 5 L bags. the Baxter product is Plasmalyte. 
they are the same stuff. they also have bicarb precursors in them. 

the 
IV sets used are those special coiled sets that Dr Donawick's company 
makes. 

give fluids continuously. 

Do give bicarbonate or a bicarb 
precursor IV: 
assume horse is acidotic. he has metabolic acidosis due to 
death of bowel, anaerobic metabolism in those cells. the best buffer is 
sodium bicarbonate. the two fluids described above contain a chemical 
that will go through the krebs cycle and turn into bicarbonate. those are 
acetate and gluconate. they add sodium acetate and sodium gluconate to 
the solution. those are the bicarbonate precursors that get converted in 
the liver. those are not enough, though. you need more than that amount 
that is included. 1 L 5% bicarb contains has 595 mEq bicarb in it. so 
that's about 600. if the horse is a little sick, give him a liter. if 
it's REALLY sick give 2 L, if it is dying, give 3 L. that's about how it 
works out. the idea is to give the sodium bicarb

DO NOT: give drugs that 
cause peripheral vasodilation, unless ssured of adequate intravascular 
fluid. acepromazine is a vasodilator. sometimes vasoconstriction is the 
only thing keeping the animal alive!

Do not: administer drugs per os 
which cause fluid to pool in the intestine, such as magnesium sulfate 
(epsom salts). this is a potent osmotic agent. when you mix up mag 
sulfate and pour it into the horse, it gets into the colon and robs water 
from the body to pull it into the colon - this is good if you have a well 
hydrated horse with an impaction, but if not, you don't want to use it.


Do not: give GI stimulants - such as neostigmine

do not: delay your 
decision to perform a laparotomy. think of this: in human surgery, a good 
general surgeon is one who when working with patients with appendicitis, 
in about 25% of the cases, when he opens the person up, finds no 
appendicitis. hospitals look at these records and if a surgeon has a rate 
such that 99% of his patients have appendicitis, he's waiting too long. 
if only 50% have it, his diagnostic acuity isn't up to par. but he should 
be doing about 25% of his appys as "abdominal airing out" or something 
:). same in veterinary medicine. we shouldn't be critical of the surgeon 
who opens an abdomen and doesn't find a life threatening lesion. if they 
all have them, they waited too long. that's how it should be. you can't 
be right all the time. 

Cases:
It is really important to listen.
Here's 
the story. this lady from CT had a horse with recurrent bouts of colic 
for two years. she called up desperate - sick of this. loved her horse, 
horse was having problems all the time and interfering with her life all 
the time. she'd had several vets check out the horse during painful 
episodes. horse always got better. whatever they did, horse always got 
better. so really it wasn't mattering what the vet did, horse was getting 
better on its own. fine. so, there is no way to ship the horse to NBC 
during an episode since it is in CT, and you don't want to hospitalize it 
for 6 mos waiting for it to happen. so we asked is there anything else to 
know about the horse? yes. one day, they found this rock like thing in 
his manure. so then we knew what was wrong. he had an enterolith. a 
concretion that forms in the colon. Dr D decided there were five of these 
in the large intestine. ...if the stone is round, it is by itself. but if 
it has flattened sides, they rub against each other and become 
polyhedral, so you can count the sides and know how many are there. so 
you open the right dorsal colon near transverse colon, to get out these 
enteroliths. 
now, there is usually a nidus for formation of these 
stones. the center of this shows us these little diamond shaped crystals  
- metallic, diamond shaped, flat - these are glazer's points. little 
triangular metal things used in framing shops to hold pictures and 
windows in place in wood frames. this horse ate a window frame. so Dr 
Donawick said to the owner, your horse ate a window. and you know what? 
he was right. ate window 3 yrs ago, 2 yrs ago started showing signs. 


slide: racehorse came in with recurrent abdominal pain. Dr D worked on 
horse for one month trying to find out what was wrong. pain seemed 
associated with feeding. this huge, watermelon like mass, was in the 
abdomen, intestine was adhered to it, and partially obstructed, and this 
was not palpable on rectal palpation. they only found it b/c finally out 
of frustration he told the ultrasound people to u/s the whole abdomen and 
find SOMETHING. this tumor hid for a whole month.
slide: small intestine 
of horse with recurrent bouts of abdominal pain. this horse has LSA - the 
thing about lymphosarcoma in horses is it is a young horse disease. 


another case of lymphosarcoma - this is in the spleen. this young horse 
owned by a young girl on long island was repeatedly seen by a vet who 
thought the recurrent bouts of abdominal pain were due to parasites. 
horse came to Dr D who delegated it w/o doing PE on his own. he sent it 
home w/o doing surgery. it came back later. so now he did a PE. he did 
ballottement of the abdomen. when he pushed on left side of horse he felt 
a bowling ball. felt nothing on rectal exam. didn't know what that was 
but thought probably it was the spleen. he told all his residents and 
students to find it. no one could. he showed it to them. no one had found 
it before. so do a full PE.

---break----

it became fashionable several 
years ago to use conveyor belt as fencing for horses. there were 
thousands of feet of this stuff glutting the market and people figured 
they'd use it b/c horses could run into it, bounce off it, not get hurt. 
but, the center of the conveyor belt material has this cord material in 
it...horses chewed the fences, ate the nylon cord, and got intestinal 
obstructions. usually at transverse colon. sometimes it would pass. 

slide: conveyor belt fencing encrusted with ingesta coming out of anus of 
horse. part of it was still stuck inside, though. 
one farm had 12 
yearlings come in with obstruction.
car tires do this too - people put 
car tires outside in the field to hold the bucket in it - and horse can 
chew the tires and get the nylon or rayon cords out of it. it's hard to 
get this stuff out - hard to get to transverse colon, b/c it is fixed to 
the back of the horse. but you can open small colon, try to pull this 
stuff out, bleh.

ok, backing up a bit - some lesions as they relate down 
the GI tract - 

Obstruction in foals:
these are high obstructions, in 
the duodenum or stomach or pylorus.
clinical signs:
frothing at mouth

profuse salivation
regurgitation of milk
gastric distension
severe 
abdominal distress
megaesophagus

these foals are 1 day to 4 mos of age

off feed, depressed, grinding teeth, sticking out their tongues.

how do 
you make a diagnosis of obstruction? use that rule about how long it 
takes water to reach cecum. give some barium - if it doesn't reach cecum 
in an hour, you have an obstruction proximal to it.

slide: radiograph of 
stomach filled with 1 L barium. 
slide: radiograph of another stomach 
with barium in it. we see some barium lying in the esophagus. we also see 
distended small intestine. this horse has an ileocecal intussusception. 


slide: this is a typical lesion. look to the left of surgeon's hand and 
see normal jejunum. in hand is duodenum - note it is smaller here - 
something makes it stricture down and get compressed and cordlike. 

slide: pyloric stricture - another variation of the disease. this pylorus 
is very small and is preventing gastric emptying. 
what can you do to fix 
this? well, you need to bypass the duodenum. you don't want to remove it 
b/c of bile and pancreatic ducts, and pancreas attached to it. but you 
want an alternate means for ingesta to leave. you can do 
gastrojejunostomy, and also can do jejunojejunostomy.

slide: another 
disease in foals. remember we talked about age related intussusception? 
here is one. altered motility as it relates to parasite migration, maybe. 
not sure.
slide: this is the intestine of a male horse. he had recurrent 
bouts of colic for years. it was a standardbred, intact stsandardbred  - 
had an indirect inguinal hernia. can see the line of adhesion where it 
went into the canal and adhered to the tunic down there. the dilated loop 
is the proximal one. no one had noticed this hernia! no one had listened 
for gut sounds in the scrotum, either.

slide: this photograph needs some 
explanation - this is small intestine, coming out through what was the 
scrotum. this horse had been castrated. it was castrated under anesthesia 
with horse recumbent, and when he stood up, the small intestine fell out 
through the incision. this is evisceration through an incision site. now, 
when you use those crushing/cutting instruments to do the castration, if 
the crush lets go, there is a hole into the peritoneal cavity. this 
occasionally happens. if this horse makes it to the referral clinic, 
without stomping on the intestines and breaking it or tearing vessels, 
chances of survival are good - because we get this case really quickly, 
they don't wait 12 hours to see how it goes. 

horse with volvulus of 
small intestine - we see the black part, and the twist. we know from 
before that 50% of these can be saved. one tidbit you need to know is, 
how much small intestine can you remove and expect it to survive? 50%. 
but you need to know how many feet of small intestine there are in the 
horse so you know when you've reached 50%. there are 70 feet, so you can 
take 35 feet and expect horse to function ok. this is a national board 
question!**

you want to remove the diseased segment, or bypass the site 
of obstruction. those are the principles of this kind of surgery. 


here's a disease where there is a quirk of nature. there is an extra band 
of mesentery - this isn't uncommon in horses. it is part of meckel's 
diverticulum - yolk sac - duplication of mesentery at jejunal-ileal 
junction - this band becomes a pocket and intestine can get incarcerated 
in there.  so there is normal mesentery, and then another sheet growing 
out the side. so intestine goes in, then pops through and gets stuck. 
"mesodiverticular band" is what traps it. this horse will show signs of 
small intestinal obstruction. distended small bowel, reflux, vascular 
compromise, serosanguinous peritoneal fluid, all the signs of 
obstruction. youwant to cut band away, resect dead bowel, anastomose. 


Ileal obstructions - the ileum is more muscular, it's terminal small 
intestine. b/c it is more muscular, and ejects stuff into cecum with 
force, it also can have some sharp material perforate it when it 
squeezes, and you can have abscesses in the wall of the ileum.

here is 
an abscess in the terminal ileum, right where it meets the cecum. 
sometimes you can palpate these per rectum, but usually you have to do an 
exploratory. what do you do? remove it? if you can't, you can bypass it - 
ileocecostomy? 

another disease horses get - ileal hypertrophy - a 
thickening of the wall of the ileum - cause unknown. other spp - guinea 
pig and pig also get this. this is another board question! ** anyway, it 
causes obstruction. surgically we just remove or bypass the affected 
area. 

these are all diseases of ileum. this is a short ileocecal 
intussuscepton, which has decreased the lumen size of ileum and caused 
partial obstruction. these horses with this, and with ileal hypertrophy, 
show a characteristic sign of pain after eating. how many minutes after 
eating? about 30 minutes. so ileal obstructive diseases that are chronic 
cause this sign. pain after eating. 

slie: anatomosis being made b/w 
intestine and cecum to bypass affected area. 

ileal-cecal 
intussusception: usually young horse, severe abdominal pain due to 
stretching of the bowel wall, nasogastric reflux b/c fluid backs up, and 
distended abdomen b/c all the small intestine is distended. on rectal we 
find distended SI causing distension of abdomen. peritoneal fluid usually 
serosanguinous with high WBC count.
these can be huge - large amounts of 
ileum can intussuscept into cecum. 
here they opened the cecum and are 
trying to push ileum out of it. sometimes they can't, they have to leave 
it and make a new anastomosis around it. 

ddx of cecal and colonic 
diseases in the horse:

diseases of cecum in order of severity:

thrombosis and embolism of cecal arteries
nonstrangulating displacements

ileal-cecal intussusception
cecal colic intussusceptoin
impaction
partial 
or complete volvulus
rupture

thromboembolic colic: usually there is hx 
of inappropriate endoparasite tx in this horses. remember the life cycle 
of the large strongyles that migrate through the cranial mesenteric 
artery and cause disease many months later? on PE you may get a clue - 
may feel an enlarged irregular cranial mesenteric artery. peritoneal 
fluid is usually serosanguinous, with high WBC count. this is b/c of 
thrombosis and death of area of cecum or colon supplied by that artery. 


last year he told a story about a client and he named the client, and it 
was a student's uncle :). these horses were owned by a man named Don 
Tissuro or something like that. He had racehorses. He was a great guy. He 
loved veterinary medicine, he gave his vets great tickets to sporting 
events. how did he get those tickets? he ran the parking facility at the 
F.U. center aka spectrum. you won't remember this but he got in trouble 
with the city b/c parking is a cash business, and the mayor decided to 
send a helicopter over the spectrum and take pictures of how many cars 
there were, counted the cars, and compared it with the amount of money 
given to the city as their share. it didn't add up. mayor got pissed off 
and took him to court and sued for a lot of money. Don loved his horses 
and didn't want to lose them so he hid them on a farm in NJ. but they 
were crowded into a small barn, small lot, not well taken care of at all. 
normal worming wasn't done. 9 mos later, these horses started arriving 
here at NBC and almost all of the broodmares died b/c of thromboembolic 
colic. slide: colic artery - all filled with clot. what happens is, the 
arterial blood supply is shut off, the wall fo the bowel dies, gut 
perforates, peritonitis ensues. there are areas that have fibrin plugs 
trying to seal holes...and other areas where there are just holes. these 
horses get fibrin patch for a while then the patch breaks. 

tx: 
supportive care. no use operating on them. resect or oversew infarcts if 
possible but really that doesn't go well esp if there is diffuse 
peritonitis. longterm - control endoparasites. 

tx: high systemic levels 
of pcn and aminoglycoside, no exploratory

disease requiring celiotomy 
for diagnosis - laparotomy is incision in flank, by the way - as done in 
human to reach appendix. laparotomy rarely done in large animals. 
celiotomy means making abdominal incision at any point.  anyway - 
colic-colic intussusception

cecal-colic intussusception - on rectal, 
can't palpate cecum. cecum falls into right ventral colon. so surgically 
you have to go in and pull it out - do a pexy to fix it in place. 


impaction of cecum - history - recent stress or diet change. this is 
another terrible disease of horses. on rectal after onset of signs 
sometimes you can feel ingesta filled, firm, greatly distended cecum. we 
miss this disease too often, with fatal results. we do not know why food 
starts to accumulate in the cecum. but it does. clues are there for 
someone who is acute, looking for them. horse is "off" a bit. there's a 
little less manure. might seem a bit painful. comes on very insidiously. 
you can't feel it, though. after a few days, there is distension of cecum 
and horrible abdominal pain. the cecum can then rupture. if you find it 
early enough, you can tx with water per NG tube. 
slide: impacted cecum

tx: empty via cecotomy - but it will fill back up again b/c it is all 
stretched out. so also do a ceco-colic (right ventral) anastomosis, or 
divert ileum to right ventral colon to go around it. diverting ileum is 
more common today - just get rid of the cecum. or, you can do a 
typhlectomy - remove the whole cecum - but not the WHOLE thing, just most 
of it.

volvulus of cecum - sometimes feel distended cecum with twisting 
bands on rectal. only tx choice is removal of cecum.

rupture of cecum - 
profound sickness, shock, on rectal empty cecum may be present, also 
sandpaper feel to serosa of abdominal viscera. there is fecal 
contamination of the peritoneal fluid. but, do not kill a horse b/c you 
find fecal contamination on abdominoparacentesis alone - maybe you stuck 
needle into the bowel.


----end---