Common drugs used in horses Flashcards
SID
BID
TID
QID
- SID - ONCE A DAY - Q 24 H
- BID - TWICE A DAY - Q 12 H
- TID - 3 TIMES A DAY - Q 8 H
- QID - 4 TIMES A DAY - Q 6 H
IA injection
intraarticular
phenothiazine used in horses
acepromazine
mild sedation for ie. transport, shoeing etc.
mode of action of acepromazine
dopamine antagonism
acepromazine positive cardiac effect in anesthesia
antiarrhythmic
(and recovery tends to be smoother)
time of onset of ace via PO and IV
PO 30 min
IV 15 min
main side effect of acepromazine
systemic hypotension which can outlast sedation
name of acepromazine paste for horse
sedazine
ace is contraindicated in what horses? (6)
dehydrated, anemic and shock horses
foals, old horses
stallions (paraphimosis and/or priapism)
main alfa2 agonist side effects in horses (5+)
ataxia
bradycardia, transient hypertension followed by hypotension (biphasic response)
GI motility and GI perfusion reduced
esophageal motility reduced
smooth muscle relaxation in upper airways (can cause stertor)
hyperglycemia, mydriasis, decrease in HCT, sweating
why should horses not eat for 2 hours after sedation with alfa2 agonists?
alfa 2 agonists decrease esophageal motility, increasing risk of esophageal obstruction
main reason to choose between xylazine, detomidine, romifidine for horse sedation?
xylazine is fairly short acting so for quick procedures (10-20 after admin.)
detomidine (30-45 min after admin.)
romifidine (about 1 hour duration) for longest procedures
what to remember about opioids in horses?
not to be used as monotherapy in horses. cause CNS excitement if admin. alone!
combine with alfa2 agonists or acepromazine
define ileus
inhibition of the gastrointestinal propulsion without signs of mechanical obstruction.
most commonly used opioids in horses (2)
butorphanol and morphine
most commonly used drug class in horses
NSAIDS
Name 6 NSAIDs commonly used in horses.
flunixin meglumine
phenylbutazone
meloxicam
ketoprofen
carprofen
firocoxib
mode of action of NSAIDs
decrease eicosanoids in inflammatory lesions by way of inhibition of cyclooxygenases (COX)
(inflammation, fever)
NSAID side effects in horses (4)
Side effects are mostly mediated by inhibition of COX-1.
decrease in intestinal motility
gastric and intestinal ulceration (ponies more sensitive)
renal damage
platelet dysfunction
Do not administer NSAIDs what route EVER?
IM
big risk of clostridial myositis!
“suppurative infection of muscle without necrosis”
flunixin is usually administered what routes (and dose)
1.1MG/KG IV, PO SID/BID
what is the most effective NSAID for visceral pain?
flunixin meglumine
what is the most effective NSAID for orthopedic pain in horses?
phenylbutazone
2.2-4.4MG/KG SID, BID PO/IV
note that phenylbutazone as a relatively narrow
therapeutic index
What NSAID should you NOT use in donkeys?
meloxicam
(is ineffective, not dangerous)
Describe meloxicam in horses.
Is more COX-2 selective than COX-1
Is not as effective as flunixin in colic patients.
Do not use in donkeys, has no effect in them.
- 0.6MG/KG IV, IM BID
- 0,6MG/KG PO SID-BID
Describe ketoprofen
in horses.
very effective analgesic and anti-inflammatory
not as effective as phenylbutazone for ortho pain, but is effective in colic
Describe carprofen in horses.
Effective analgesic but weak anti-inflammatory.
More COX-2 selective than flunixin or phenylbutazone but less so than meloxicam.
No data on effect on colic pain.
Best on inflammatory pain.
Describe coxibs in horses.
very strongly cox-2 selective
Firocoxib (previcox) requires a “loading dose”.
PO and IV
Similar analgesia as flunixin for acute colic.
Do NOT flush with saline, flush with (back-drawn) blood (precipitates).
Name the main spasmolytic used in horses.
butylscopolamine 0,1-0,3MG/KG IV
used for colic and rectal exams.
the analgesic effect lasts approx. 20 min
what is butylscopolamine sometimes combined with
dipyrone
a painkiller, spasm reliever, and fever reliever drug.
what cardiac change can butylscopolamine cause?
tachycardia
describe lidocaine use in horses
as an analgesic, usually CRI with loading dose. monitor heart rate and watch for tremors.
colic and ileus treatment. decreases reperfusion injury.
reperfusion injury
defined as the paradoxical exacerbation of cellular dysfunction and death, following restoration of blood flow to previously ischemic tissues.
Mechanisms of injury involved in vascular reperfusion are three-fold:
- Increased formation of reactive oxygen species.
- Microvascular vasoconstriction.
- Adhesion of neutrophils to endothelial lining, their activation, and release of cytokines
Name 3 common local anesthetics used in horses.
lidocaine (shortest duration)
bupivacaine (slow onset, longest duration(6h) most potent)
mepivacaine (least irritation, intermediate duration; pretty ideal for most procedures)
Which local anesthetic would you use for intra articular injection?
mepivacaine
rapid onset, least irritation and least toxic to chondrocytes. less vasodilation.
penicillins used in horses (2)
procaine benzylpenicillin (IM)
Na-benzylpenicillin (IV)
most common side effects of penicillins in horses
soft feces, and sometimes diarrhea
aminoglycosides used in horses (2)
gentamicin
amikacin
since penicillins are against gram pos., they are often combined with?
aminoglycosides (which are against gram neg. mostly)
side effects of aminoglycosides (2)
nephrotoxicity (check crea before admin.)
ototoxicity
what to note when administering alfa 2 agonists and potentiated sulfonamides in horses?
keep min. 15min between sedative and AB as too soon can cause sudden volatile drop in blood pressure (also arrythmias and death poss.)
name 2 common potentiated sulfonamides used in horses (2)
trimetoprim + sulfamerazine PO
trimetoprim + sulfadiazine IV (Slowly! to avoid seizures and never admin. to sedated horses (alfa2 interaction))
What musculoskeletal condition is oxytetracycline used for in foals?
tendon contracture
only in neonatal foals, given once in a very high dose in combo with splinting.
The mechanism by which oxytetracycline helps in the resolution of tendon contracture in foals is not entirely understood, but there are several proposed theories:
- Oxytetracycline has mild anti-inflammatory properties.
- Oxytetracycline has been shown to inhibit the activity of matrix metalloproteinases, enzymes involved in tissue remodeling and repair, including the turnover of collagen in tendons.
- Some studies suggest that oxytetracycline may affect the growth plates of bones in young animals.
- There is some evidence to suggest that oxytetracycline may have neuromuscular effects, potentially influencing muscle tone and contractility.
Name 2 common tetracyclines used in horses.
doxycycline
oxytetracycline
Describe doxycycline in horses.
Broad-spectrum
Can never be given IV! causes collapse and death this route.
So, 10 mg/kg PO BID.
Describe oxytetracycline in horses.
Given IV, 5-10 mg/kg BID.
Give very slowly and as a dilution infusion. Can cause hypotension and collapse, phlebitis.
Nephrotoxic
Cefalosporins in horses.
not often used in horses
- gen: foals only
cefalexin
cefazolin
cefadroxil - gen. can be used in adults
why avoid fluoroquinolones in foals?
can cause arthropathies
such as enrofloxacin
Name 2 common fluoroquinolones used in horses.
enrofloxacin
marbofloxacin
Why choose marbofloxacin over enro-?
Considered to cause less arthropathies than enro-.
describe a nitroimidazole used in horses
metronidazole; PO, PR (per rectum)
anaerobes, protozoa
side effects: inappetence, diarrhea
not for use in animals intended for human consumption!
main 2 systemic glucocorticoids used in horses
dexamethasone
prednisolone
note: laminitis risk
2 inhalatory glucocorticoids used in horses
flu-ti-casone
cicle-sonide
these are safer regarding side effects vs PO glucocorticoids.
for resp. diseases, systemic glucocorticoids are used much less commonly than these inhalatory ones.
drugs that decrease gastric acid production that are used in gastric ulcer treatment of horses (2)
omeprazole (proton pump inhibitor)
esomeprazole (proton pump inhibitor)
protective drugs used in gastric ulcer treatment of horses (3)
sucralfate
misoprostol
ranitidine (H2-receptor agonist)
sucralfate in horses
Binds to ulcerated mucosa, stimulates mucous secretion, PGE synthesis, enhances blood flow.
At least 30 min after other oral medication (decreased absorption of other drugs).
Should be added to every glandular ulcer treatment protocol.
misoprostol use in horses
Suppresses gastric acid production; also anti-inflammatory effect.
May cause abdominal pain;
Better absorption from empty stomach.
Only for glandular ulcers.
ranitidine use in horses
Suppresses gastric acid production; also anti-inflammatory effect.
Less effective than other options; sometimes used to follow up omeprazole.
drug use in foals
foal are NOT small adult horses, very different metabolism of many drugs.
different dosages and dosage intervals.
use all drugs with caution in foals, especially sick foals.
IVRLP
intravenous regional limb perfusion
is a well-established method for delivering high antimicrobial concentrations to the equine distal limb for preventing and treating equine orthopedic and soft tissue infections.
locations for IM injections in horses (4)
neck (use upper 1/3 of neck as carotid will be tucked away deeper and you dont want to hit it)
pectorals
gluteals
semimembranosus
absorption varies based on site.
possible reactions: abcesses, cellulitis, swelling, pain.
what types of drugs are given SC in horses? (3)
very few systemic drugs
local anesthetics
nerve blocks
difference between inhaler and nebulizer
An inhaler uses a chemical to push the medicine into the lungs or the medicine is a fine powder.
Nebulizer: A nebulizer is a electric- or battery-powered machine that sprays a fine, liquid aerosol of medicine.
How do you apply an inhaler to a horse.
Put the inhaler on one nostril, let the horse inhale 1-2 min.
