2. Drug Routes
Drugs may be administered in various ways.
The route chosen depends on the part of the
body the drug needs to affect, how quickly
the drug needs to work, and the ability of the
owner to give the drug.
3. Routes of administration
Oral
Parenteral
IV IM IP IC SC
Other
Topical
Rectal
Intrauterine
Intramammary
4. Advantages of Oral
medication
Usually least painful
Can be administered by client
Skin not penetrated, less risk of introducing infection
5. Disadvantages of Oral medication
Aspiration of medication - choking,
pneumonia (eg paraffin to cats)
Variable rate of absorption depending on
patient, contents of gut, etc.
Vomiting, irritation of gut (eg aspirin)
Patients may not tolerate administration
May be difficult to ensure correct dosage
7. Tablet
Compressed drug in a carrier such as chalk
or sugar
Often coated
to protect drug inside from moisture
to disguise unpleasant tastes
to protect from gastric juices, slow down the breakdown
of the drug for a slower release
to avoid irritation
to give the tablet a recognizable colour
Usually scored into halves or quarters for
ease of breakage for more accurate dosing
Most common form of medication
10. Capsule
Bullet-shaped, gelatin container
Contains powder, granules or liquid
Easier to swallow (smooth)
No need for 'carrier'
Gelatin dissolves in stomach
12. Paste
Semi solid preparation
Usually in a water soluble base
Via syringe
Easy for owner to use
Rabbit, guinea pig
Horse (worming paste)
Cat (worming paste)
13. Liquid
Syrup
Drugs contained in a concentrated sugar solution.
Good for young animals/small doses (eg Clavulox drops).
Solution
Drug in liquid form or dissolved in water (eg glucose solution).
Suspension
Insoluble particles float in liquid but settle when standing
Needs to be mixed before use (shaken)
Emulsion
Two immiscible liquids (eg water and paraffin).
14. Routes of enteral liquids
Directly into the mouth
By crop needle (birds)
By stomach tube
Drugs which burn the mouth
Very young animals, to reduce the risk of
aspiration
Large volumes of fluid.
15. Parenteral Preparations
These are drugs that can be given by injection. All
drugs in this form must be sterile. The most common
routes of injection of drugs in small animal practice
are iv ,im,ip,sc,ic
Usually taken to mean ‘by injection’
Strictly, par-enteral = ‘adjacent the gut’
16. Injection Route depends on
Type of drug
Condition and temperament of patient
Volume of the drug,
Required speed of action
17. Systemic Drugs
Some drugs cannot be applied directly where
they are needed. Instead they need to travel
through the animal’s system until they get to
where they are needed. These drugs are said
to be given SYSTEMICALLY.
Examples include oral preparations and
injections
20. Intradermal (ID)
Into the dermis
The living part of the surface layer
Needs a very fine needle
Causes a blister like appearance (bleb) if
performed correctly
allergy testing
tuberculin testing
21. Subcutaneous (SC)
Under the skin
Most common site
Loose skin over shoulder blades a
good site
Less painful than intramuscular
injections
Only for low irritant drugs
Slow absorption if dehydrated
Used for most vaccines
22. Intramuscular
Injected deep into the body of a
muscle
Less likely to cause an overt tissue
reaction
Insert needle at right angles to the
skin
Larger volumes may be injected in
the one site than with other routes
Faster absorption than s/c
24. Intravenous (IV)
Into the vein directly
Fastest onset of action
Can give irritant solutions into the vein which
cannot be given IM or SC
Irritant drugs should be given via an
intravenous catheter, (caparsolate,
thiopentone, guifenasin)
25. Peri-vascular Necrosis
When irritant solution leaks from a vein
and enters
area may 'slough‘
Immediately inject the area with
saline (isotonic i.e. 0.9% NaCl) to
dilute the drug
26. Intra-peritoneal (IP)
Into peritoneal cavity
Usually near umbilicus
Or half way between umbilicus &
pubis
Used for
Rodents
Birds
Euthanasia of young difficult patients
27. Intra-cardiac (IC)
Injection through the chest wall into the
heart
Emergency administration of drugs
during cardiac resuscitation
e.g. adrenaline
Euthanasia
Moribund animals
30. Intra-articular
Injection into the joint space
Needs full surgical preparation
should also wear gloves and draw drug up
in a sterile manner, new unused bottle, etc,
to avoid introduction of infection.
Used for
Dogs (eg cortisone with greyhounds,
Cartrophen)
31. Epidural
Injection into the epidural space surrounding
the spinal cord usually in the lumbar site
Full sterile prep needed
Animal positioned on sternum, with back
legs drawn forwards
Used for
Before an orthopaedic procedure on spine
or hindquarters
Pain relief (eg morphine, local anaesthetic
for dog)
Stops straining and gives pain relief,
(lignocaine, xylazine).
35. Supplies Needed
Before giving an injection, gather the following:
The drug or substance to be injected.
Alcohol swab or alcohol moistened cotton
ball
Correct size syringe
Correct size needle
Sharps Container- a hard plastic with a screw-
on or tightly-secured lid
36. Factors to Consider
When choosing needle size, syringe size, and injection
site / route of injection there are several factors which
need to be considered:
The type of the solution / medication.
The viscosity (Thin / watery? Thick / sticky?)
The absorption rate for the solution / medication.
The size of the patient (Beagle? Hound? Something larger?)
The mobility status of the patient (Anesthetized? Immobile?
Fully conscious?
42. Factors to Consider: IM
Injections
Intramuscular injections may be performed
in the thigh muscles on the front of the
rear limb, or using the hamstring muscles on
the back side of the rear leg
If blood is aspirated, the needle should be
removed as this indicates needle placement
in a blood vessel. Reinsert the needle at a
different site.
Needle sizes used for IM injections range
from 25 to 20 gauge. Muscle is dense tissue
and can only accommodate small volumes of
fluid
43. Triceps muscle
The triceps muscle belly located caudal to
the humerus is one IM injection site. The
left thumb is placed on the humerus,
isolating the muscle belly in the left hand.
The needle is placed in the muscle belly.
The plunger is withdrawn to create
negative pressure.
44. Quadriceps muscle
The quadriceps muscle is located
anterior to the femur. The left
thumb is on the femur. The needle
is inserted at a right angle to the
muscle belly.
45. Semitendinosis muscle
Administering an injection into the
semimembranous/semitendinosis muscle
group, the tip of the needle (white arrow)
should be directed toward the caudal
aspect of the limb so if the patient moves,
the needle will not advance toward the
sciatic nerve. Notice the left hand is being
used to isolate the muscle group caudel to
the femur.
46. Lumbar muscle
The dorsal lumbar muscles on
either side of the midline can be
used for IM injections. The thumb
of the left hand is on the transverse
processes of the lumbar vertebrae.
47. Factors to Consider: SC
Injections
For SQ (subcutaneous) injections, in general, use:
An 18 or 20 gauge needle, 1 to 1.5 inches long.
SQ medications are deposited into the loose connective
tissue just below the dermis.
This tissue is not richly supplied with blood vessels so the
absorption rate is slow.
There are many pain receptors in this tissue so only non-
irritating, water-soluble medications in small doses should
be given by the SQ route.
48. The loose skin over the
shoulders and neck is an
ideal site for
subcutaneous injection.
50. Topical medications
External surfaces
eg the skin, eyes, ears
Exposed mucous membranes
eg gums, nasal mucosa, prepuce and
penis, vulva and vagina.
Medication may work
Topically - on only the area to which it is
applied
(eg ringworm ointment)
Systemically (eg Spotton, Ivomec Pour On,
DMSO)
51. Cream
CREAMS – the drug is dissolved in water and mixed
with oil or fat. Creams spread easily and penetrate
the outer layers of the skin
A semi-solid water-soluble emulsion which
penetrates the skin surface
Tubes or plastic squeeze bottles
Wash off with water.
52. Ointment
OINTMENTS – the drugs are present in a base of wax
or fat. They do not penetrate the skin.
Semi-solid oil-based preparation, usually with a base
of wax or jelly
Comes in tubes, jars, etc.
Does not usually get absorbed by the skin, (eg
prednoderm).
53. Suspension
Liquid preparation in which particles suspended in
the liquid
Will separate out on standing, so needs to be
shaken, (eg calamine lotion, yellow lotion)
54. Rinse/Wash/Solution
Liquid which often diluted and poured on an animal
May have a residual action when dry, (asuntol,
otoderm, ectodex).
55. Aerosol
SPRAYS – a way of applying liquids in fine droplet
form
Liquid under pressure
Sprayed on as particles of liquid suspended in air,
(eg chloromide, debrisol, frontline, fly repellent)
56. Powder
Finely particulate solid preparation which dusted on
Can be irritant to open wounds
May help to dry weeping wounds, (eg tricin powder,
pinkeye powder)
57. MEDICATED SHAMPOOS
MEDICATED SHAMPOOS – drugs mixed with
detergents which penetrate the coat. Shampoos
are left in contact with the skin for the
recommended amount of time and then should be
rinsed off thoroughly.
58. EYE & EAR MEDICATION
EYE & EAR MEDICATIONS – these are both examples
of topical medication.
Eye medications should be sterile. Once they have
been opened they should be stored only for the
length of time recommended by the manufacturer.
59. Aural medications
Drops or Ointments
The ear is ideally cleaned of wax and
discharge before administration of
medication
61. Enema
Commercial solutions
Syringe, tube or pack (eg Microlax®
)
Soapy water
Funnel and tubing
Other substances
paraffin, bloat treatment (Tympanyl®)
)
62. Suppository
Bullet shaped, semi solid, glycerine based
Melts at body temperature
Can contain antibiotics, laxatives, soothing agents
May be absorbed systemically
64. Pessaries
Large tablets
Usually antibiotic
May also have a foaming agent
Administered by hand when the cervix is open for
example, after a calving
65. Intra-uterine fluids
Administered via the cervix with a pipette or balloon
(Foley) catheter
During oestrus when the cervix is relaxed
Some will remain in the uterus, while others will be
siphoned out again
66. Health & Safety and
Administering Medicines
Health and safety should be considered in order to
make sure that we don’t get hurt whilst
administering medicines.
It is also important to ensure that the animal doesn’t
get hurt or frightened.
67. What are the risks to animals
when administering
medicines?
Overdose
Allergic reaction
Wrong administration route selected
Animal stressed
Animal gets injured
68. How can these risks be
minimised
Follow instructions carefully
Make sure that the animal is adequately restrained
Use sprays in a well ventilated area
Wear appropriate PPEs (e.g. gloves, mask etc)