20 – Vomiting and Diarrhea Flashcards
1
Q
Why is vomiting a good thing (what causes you to vomit)?
A
- Removal of toxic/irritant material
- Prevention of gastric rupture with ‘obstruction’
2
Q
Where is the emetic center located?
A
- In the medulla
3
Q
What are some things that cause you to vomit?
A
- Info from pharynx, viscera, cerebral cortex
- *important to know what is causing it to know how to TREAT it
4
Q
When are emetics commonly used?
A
- After toxin ingestion
o More rational to use right after toxin ingestion - Little evidence to demonstrate efficacy
5
Q
What are some examples of emetics?
A
- *Apomorphine
- Alpha-2 agonists (emetic for cats via IM injection): CRTZ
o Xylazine and Dexmedetomidine (50% in cats) - For people to try at home
o Hydrogen peroxide (dogs)
o Saturated salt solution (dogs)
6
Q
What is Syrup of Ipecac
A
- Causes GI irritation leading to vomiting
- NOT really used in vet med
7
Q
Apomorphine
A
- Dopamine agonist in CRTZ (chemoreceptor trigger zone)
- 90% effective in dogs
o Less effective in cats - Administered in IV (or conjunctiva=no one does it)
- *no analgesia (not a controlled drug)
8
Q
What are opioids that may be used to induce vomiting?
A
- Morphine
- Hydromorphone (anesthesia pre-med)
- *why fast before surgery
9
Q
What are some reasons animals get sick (and vomit)?
A
- Motion sickness
- Parvo virus
- Gastroenteritis
- Chemotherapy
- Uremia: cats with renal failure
- Hair balls
10
Q
What are the phenothiazine drugs (sedatives) that can STOP vomiting?
A
- Acepromazine: injectable and powder only
11
Q
What does acepromazine do?
A
- Antagonizes dopamine
o Inhibits the CTZ - Can DECREASE vomiting from OTHER CAUSES (ex. motion sickness)
o When sleeping=don’t get motion sick - Anti-histamine: dogs
- Weak anticholinergic: cats
12
Q
What are the adverse drug events with Acepromazine?
A
- Hypotension due to alpha-adrenergic blocks
- Excessive sedation
- Extrapyramidal signs (aggression)
- Lowers seizure threshold in epileptics
- Prolapsed 3rd eyelid, CYP-mediated drug interactions
13
Q
Anticholinergic drugs
A
- Block cholinergic afferent pathways from GI tract and vestibular system to emetic center
- *humans NOT animals
14
Q
Antihistamines (H1 blockers)
A
- Block nerve transimission responsible fro transmission of VESTIBULAR STIMULI to the emtic center
- Mild sedation
o Ex. Benedryl, Gravol
15
Q
Metoclopramide (injectable solution)
A
- Low doses: inhibits DOPAMINE in CNS
- Peripheral prokinetic effect: increases gastric acid and upper duodenal emptying
- High doses: inhibits serotonin receptors in CRTZ
- *was popular in small animals, but highly VARIABLE PK
- Extrapyramidal effects
16
Q
Ondansetron
A
- Very potent anti-emetic
- Very expensive! ($200/vial (one dose))
- *inhibits 5-HT1 (serotonin) receptors on vagal nerve and CRTZ
- *very good for chemotherapy, NOT motion sickness induced vomitting
17
Q
Why is Ondansetron useful as an anti-emetic during chemotherapy?
A
- Cytotoxic drugs and radiation releases serotonin from enterochromaffin cells in small intestine
18
Q
Maropitant (Cerenia)
A
- Neurokinin (NK1) receptor ANTAGONIST
o Blocks binding of substance P (tachykinin) at emetic center - *works with various causes of emesis: stops everything causing vomiting
- *acute vomiting (2mg/kg): dogs and cats
- *motion sickness (8mg/kg=higher dose): dogs ONLY
o Still probably going to use acepromazine
19
Q
Other uses of Maropitant?
A
- May have analgesic and anti-inflammatory effects
o Blocks substance P - May reduce inhalation anesthesia (MAC)
- *NOT CONSISTENT
20
Q
What are the 3 parts of diarrhea treatment?
A
- Fluid therapy
- Electrolytes
- Acid/base treat
21
Q
Fluid therapy to treat diarrhea
A
- *MOST IMPORTANT
- Diarhea does NOT kill animal, dehydration and acidosis does!
- Oral, IV, subcutaneous, etc.
22
Q
What must an oral rehydration therapy contain?
A
- Water
- Na
- Cotransporter
- *no matter how damage the mucosa is=the rehydration will go through
23
Q
How does Na enter the mucosa cell (4 ways)?
A
- Na channel
- Na-glucose co-transport (SGLT1)
- Na-amino acid co-transport
- Na-H+ exchanger (NHE3)
- *use COTRANSPORT to maximize Na absorption!
24
Q
Electrolytes to treat diarrhea
A
- Replace Na, Cl and probably K
25
Acid/base balance treatment for diarrhea
- Bicarbonate to treat ACIDOSIS
o Can’t just give it orally
- Metabolizable substrates that provide bicarb
o Ex. citrate, propionate, acetate
*usually more in calves
26
Calf-lyte for calves contains
- Lots of dextrose
- NaCl
- Glycine (AA)
- Some K
- Sodium acetate: bicarb donor
27
What do people use to treat diarrhea?
- Kaolin-Pectin: ‘chalk solution’
o ‘sooth gut’
o Used to mix morphine in it
- Activated charcoal
- Bismuth subsalicylate (Pepto-bismol): ‘travellers diarrhea’
o Bismuth: coating (turn feces black)
o Aspirin: anti-PGE
o NO EVIDENCE
28
Anticholinergic drugs to help with diarrhea?
- Decrease intestinal motility and secretions
- BUT: there are very few cases of diarrhea that are hypermotile
o May actually worsen it be creating a ‘stove pipe’ effect
- Systemic side effects (ex. tachycardia)
29
Hyoscine butylbromide (Buscopan)
- Antispasmodic and anticholinergic for horses
- Colic to supress spasms
- NO EVIDENCE as an anti-diarrheal
- Can cause tachycardia and decrease gut sounds
30
Opioids
- Anti-secretoy and anit-motility effects by action on mu-receptors in GIT
- Decrease intestinal contractions and increase segmentation=overall constipating effects
- Increase tone of GI sphincters
- Stimulate absorption of fluid and electrolytes
31
What is an example of an opioid that may ‘treat’ diarrhea?
- Loperamide (Imodium)
- (Diphenoxylate)
- (Paregoric)
32
Loperamide (Imodium)
- Maybe works? But normally your diarrhea will go away in a day or two
- *don’t use with infectious diarrhea or dogs with ABC-B1 deletion
33
Antimicrobial therapy for diarrhea
- Only use those for KNOWN BACTEIAL CAUSES
- But they can often CAUSE DIARRHEA
o Bacterial flora is screwed up already and you’ll impact that more (ex. Nuflor, Baytril)
- *may result in ‘carrier’ animals (ex. Salmonella, Campylobacter)
34
What can happen in animals who are profoundly diarrheic?
- breakdown in barrier and may be able to translocated into the blood=secondary septicemia
- *use antibiotics to treat the secondary septicemia and NOT for the diarrhea
- Ex. neonatal calf with not enough colostrum
- Ex. parvo puppies
35
Beware of OTC calf scour boluses!
- Don’t bother
- *not providing them with any fluids
- May likely be a viral infection and wont work anyways
- MOST will get better on their own without treatment
36
NSAIDs for diarrhea
- Meloxicam label claim for calf diarrhea (w/oral fluid therapy )
- Ketoprofen
- Flunixin: only when blood present in feces
- *risk of renal adverse events=will reduce renal blood flow even more!
o Do NOT be dehydrated and take NSAIDs
- *may help if there is inflammation in the gut, but often that is not the case
37
Meloxicam for dairy calves with naturally-occurring diarrhea?
- Increased appetite
- Faster rate of grain
- No change in weaning weight
- *maybe just makes you fell slightly better
38
Crofelemer (Canalevia-CA1) in USA
- Conditionally approved for chemotherapy-induced diarrhea in dogs
- Botanical mixture in a delayed-release oral tablet
- Inhibits channels to reduce ion flux=reduced osmotic gradient in lumen=decrease fluid efflux
39
NOTHING REALLY WORKS TO TREAT DIARRHEA, GIVE THEM FLUIDS!
- Still give food orally=can help the gut lining heal faster
- *small amounts of highly digestible food (ex. chicken and rice)
