In a busy veterinary practice, a veterinary technician often administers treatments ordered by the veterinarian. Proper administration techniques should be used along with accurate documentation on the medical record. Additionally, a veterinary technician must be knowledgeable about dosage forms, syringe construction, and hatch marks and must be able to draw correct amounts of medication within a syringe, know the six rights of drug administration, be capable of administering medication by all available routes, be knowledgeable in the area of client education regarding drugs, and know how to properly handle controlled substances. Proper documentation of administered treatments is of utmost importance and ensures that the same treatment is not repeated by other veterinary personnel. Knowledge of adverse reactions that animals may have to particular medications is also crucial. The veterinary technician is the veterinarian’s most important employee in a busy practice. Through observation of the patient during treatments, the technician is able to provide the veterinarian with information regarding the patient’s response. The doctor, thus informed, can easily reach decisions regarding adjustment of the treatment regimen. The technician who recognizes the importance of administering proper treatment to the patient and who uses observation skills in assessing patient response to that treatment is an invaluable asset to the practice.

Dosage Forms

Pharmaceutic companies manufacture drugs in various forms. Some drugs are available in a variety of forms; others may be available for administration in only one form. Most pharmaceutic companies endeavor to provide comfort to the patient and ensure ease of administration when formulating their drugs. Some common drug preparations may be administered orally, parenterally, through inhalation, intrarectally, and topically. The most common type of preparation is an oral medication. Oral preparations are usually easy to administer, have extended expiration dates, and are manufactured uniformly with respect to the content of the drug.

Tablets are the most commonly used oral form (Figure 2-1). A tablet may be scored or unscored. A scored tablet has indentions that have been made into its surface, allowing it to be broken into halves or quarters. Therefore, a scored tablet provides a way of administering a smaller dose to the patient. A tablet that is unscored may be cut into a smaller size with the use of a pill cutter device. However, scored tablets break more readily and are less likely to fragment. Some tablets whose drug type may be irritating to the gastrointestinal tract may be enteric-coated. Capsules are containers that house medication. The capsule itself may be made of gelatin and glycerin. The contents of a capsule may be in powder or liquid form. Capsules may be advantageous to use because they allow a patient to be treated without an unpalatable taste coming into contact with the oral mucosa. Unfortunately, capsules cannot be broken down the way a scored tablet can to provide a smaller dose. Boluses are large rectangular tablets that may be scored or unscored. Boluses are used in the treatment of large animals (e.g., cattle, horses, sheep). Boluses usually are administered to bovines with the aid of a special instrument called a balling gun.

FIGURE 2-1 Tablets and capsules are the most common forms of oral medications.

Liquid preparations for oral administration may be purchased in several different forms (e.g., mixtures, emulsions, syrups, or elixirs). Mixtures consist of aqueous solutions (i.e., water) and suspensions for oral administration. A suspension usually separates after long periods of shelf life and must be shaken well before it is used so that a uniform dose is provided. Syrups contain the drug and a flavoring in a concentrated solution of sugar water or other aqueous liquid. In veterinary medicine, an antibiotic (e.g., doxycycline) may be mixed with a liquid vitamin (e.g., Lixotinic) to ensure a more palatable taste for the patient. Elixirs usually consist of a hydroalcoholic liquid that contains sweeteners, flavoring, and a medicinal agent. Emulsions consist of oily substances dispersed in an aqueous medium with an additive that stabilizes the mixture. All liquid oral medications should be administered slowly to allow the patient to swallow before more liquid is given. Rapid administration of oral medication can result in aspiration into the lungs, thereby causing pulmonary problems.

Technician Notes

Rapid administration of oral medication can cause the liquid to be aspirated into the lungs, thereby causing pulmonary problems.

Two forms of parenteral injection that are available are injections and implants. Injections are available as single-dose vials, multidose vials, ampules, or large-volume bottles that may be used to administer intravenous (IV) infusions (Figure 2-2). A vial is a bottle that is sealed with a rubber diaphragm. A vial may contain a single dose or multiple doses. A single-dose vial must be discarded after one use (dose). Multidose vials usually contain preservatives that enable them to have a longer shelf life; thus they may be used for more than one dose. Ampules contain a single dose of medication in a small glass container with a thin neck, which is usually scored so that it can be snapped off easily. Some drugs may be unstable in solution and may require reconstitution with sterile water or another diluent; these may be used immediately for injection (Procedure 2-1).

Technician Notes

It is a good idea to place a paper towel over the neck of an ampule before breaking it, to protect the fingers from glass cuts.

FIGURE 2-2 Parenteral medications are supplied in single-dose vials **(A),** multidose vials **(B),** ampules **(C),** and large-volume bottles or bags used for intravenous administration **(D).**

Procedure 2-1

Reconstitution of a Medication

Materials Needed

Syringe of adequate size for the amount of diluent with a needle attached

70% isopropyl alcohol

Cotton swab

Procedure

1. Clean the rubber diaphragm of the medication vial and the diluent vial with an alcohol swab (Figure 2-3, A).

2. Remove the needle cap and pull back on the plunger to fill the barrel with air equal to the desired amount of diluent. Inject the air into the vial of diluent to create positive pressure and to ease withdrawal (Figure 2-3, B). Invert the diluent vial and withdraw the desired amount of diluent.

3. Inject the diluent into the medication vial and withdraw the syringe and needle. Shake the vial to mix well (Figure 2-3, C).

4. Positive pressure may be created in the freshly mixed medication vial before the desired amount of medication has been withdrawn. Once the medication has been withdrawn (Figure 2-3, D), label the syringe, and administer the drug to the patient. After withdrawing the patient’s medication, dispose of the vial, or store it according to the label.

Syringes and needles are used for parenteral administration of drugs (Box 2-1). This equipment must be sterile. Drugs should never be stored in syringes for a long time before administration occurs because some drugs may be absorbed into the plastic makeup of the syringe, resulting in an inadequate dose or inactivation of vaccines.

Technician Notes

All used needles should be discarded properly into a sharps container.

Box 2-1

Syringes and Needles

Syringes

Syringes are available in various sizes and styles. The most commonly used sizes are 3 mL, 6 mL, 12 mL, 20 mL, 35 mL, and 60 mL. Syringes may be ordered from the manufacturer with or without an attached needle. The tip of the syringe, where the needle attaches, can be one of four types: Luer-Lok tip (Figure 2-4, A), slip tip (Figure 2-4, B), eccentric tip (Figure 2-4, C), or catheter tip (Figure 2-4, D). Each type of tip has its own advantages and disadvantages and is often chosen because of personal preference. A complete syringe consists of a plunger, barrel, hub, needle, and dead space (Figure 2-5). The area in which fluid remains when the plunger is completely depressed is called dead space.

Tuberculin syringe

A tuberculin syringe (Figure 2-6) holds up to 1 mL of medication. It usually is available with a 25-gauge or smaller attached needle. This syringe is commonly used for injections of less than 1 mL. Some tuberculin syringes have a dead space. Although the patient receives the proper amount of medicine, some liquid remains in this dead space, thus wasting the drug and costing the practice money. This is also important to remember when a tuberculin syringe is used to draw up controlled substances. The dead space will cause the controlled substance log book to reflect more controlled substance used than was actually administered from the vial. Thus, the dead space should be considered when amounts used are documented. Some tuberculin syringes are manufactured with low dead space or no dead space at all. In the case of syringes with no dead space, the needle screws into the tuberculin syringe instead of attaching to the tip.

Multidose syringe

A multidose syringe (Figure 2-7) is commonly used for large animals in cases when several animals require the same injection. It allows the user to set the dose and to give repeated injections until the barrel is empty of medication. This type of syringe may be disassembled and disinfected for reuse.

Insulin syringe

An insulin syringe (Figure 2-8) usually is supplied with a 25-gauge needle, and differing from other syringes, it has no dead space. The syringe is divided into units instead of milliliters and should be used only for insulin injection.

Figure 2-9 illustrates the importance of being familiar with the different types of syringes and the units of measurement found on each. This is necessary to ensure that one can draw up an accurate amount of medication.

FIGURE 2-9 Examples of how to read amounts of medication contained in a syringe.

Needles

Needles are available in various sizes and styles, but all needles have the following three parts: hub, shaft, and bevel (Figure 2-10). Needle sizes vary by gauge and by length (Table 2-1/Figure 2-11). The gauge refers to the inside diameter of the shaft; the larger the gauge number, the smaller the diameter. The length of the needle is measured from the tip of the hub to the end of the shaft. Lengths longer than 1 inch usually are used in large animals and occasionally for biopsy. The bevel is the angle of the opening at the needle tip. It is often helpful when venipuncture is performed to have the beveled side of the needle facing up before the needle is inserted into the patient.

FIGURE 2-10 A needle consists of three parts: hub, shaft, and bevel.

TABLE 2-1

Commonly Used Needle Gauges for Different Animals

ANIMAL	NEEDLE GAUGE
Swine	16, 18
Cattle	16, 18
Horses	16, 18, 20
Dogs	20, 21, 22, 25
Cats	22, 25
Small exotics	23, 25, 27

Bleeding needles (Figure 2-12) may be up to 3 inches long, are large gauge (14 to 16 gauge), and usually are used for obtaining blood from cattle and swine. These needles are made of stainless steel and are reusable after proper cleaning and disinfecting.

FIGURE 2-12 Stainless steel bleeding needles. (From Sonsthagen T: Veterinary instruments and equipment, St. Louis, 2011, Elsevier.)

Implants are very hard sterile pellets that contain a chemical or a hormonal agent. Implants are inserted subcutaneously and are absorbed by the body over an extended time. Growth hormones are commonly manufactured in this form for use in cattle and are implanted in the subcutaneous dorsal aspect of the ear.

Topical medications are available in several forms. Liniments are medicinal preparations for use on the skin as a counterirritant or to relieve pain. Lotions are liquid suspensions or solutions with soothing substances that may be applied to the skin. An ointment is a semisolid preparation of oil and water, plus a medicinal agent. The water in an ointment evaporates after application and leaves the drug behind on the skin’s surface. Dusting powders (e.g., flea powder) are mixtures of drugs in powder form for topical application. Additionally, powders may have adsorbent (cornstarch) or lubricant (talcum) properties. Aerosols are drugs that have been incorporated into a suitable solvent and packaged under pressure with a propellant. Dusting powders and aerosols are common forms for some topical insecticides and wound dressings.

Microencapsulation is a drug form that stabilizes substances commonly considered unstable. Microencapsulation also may be used for drugs intended to be released slowly over a period of time (e.g., moxidectin [ProHeart injection]). When the drug’s active ingredients are microencapsulated, a protective environment is formed against harmful substances and the stability of the product is improved. Microencapsulation completely masks the flavor of a drug and allows oral treatments to be administered with greater ease because the patient is unable to taste or smell the ingredients.

Drug Preservatives and Solvents

In addition to the active ingredient, many drugs contain organic or inorganic agents as additives or pharmaceutic aids. These inactive (or inert) ingredients facilitate tablet administration, improve solubility, or increase stability. Although the quantity of inert ingredients is usually small, these ingredients can cause adverse effects, or a patient may be sensitive to or may smell the ingredients.

Parenterally administered drugs often contain chemical preservatives that are used to prevent destruction and loss of potency through oxidation or hydrolysis. The amount of preservative in the formulation of parenterally administered drugs is an optimal concentration, and the reconstituted medication should be used immediately to prevent the possibility of fungal or bacterial growth. Dilution of the drug reduces the effectiveness of the preservatives. Most drugs are water soluble, although some may need additives to increase solubility. Glycols are one example of additives used to increase solubility. Generally, propylene glycol and polyethylene glycols are preferred.

Technician Notes

Some vaccines may contain antibiotic preservatives. Care should be taken by personnel during reconstitution of these vaccines because liquid that escapes from the rubber seal of the vial could be sprayed inadvertently into an allergic person’s eye (e.g., those persons with hypersensitivity to penicillin).