Veterinary Pharmacy
A complete walk-through of veterinary pharmacy — from the organisations that built the specialty, to the laws governing animal medicines, the language veterinarians use, and the compounding science that keeps animal patients alive when no approved product exists.
01What veterinary pharmacy actually is
Veterinary pharmacy is the branch of pharmacy practice concerned with the safe, effective and legal use of medicines in animals. It sits at the intersection of three disciplines that are usually taught separately: pharmacology, clinical practice and regulatory law — applied to a patient population that cannot describe its own symptoms.
Pharmacists occupy a unique position in this field. They are the only healthcare professionals who are legally permitted, and socially expected, to provide competent pharmaceutical care and products across all species. Yet the same pharmacist who can counsel a human patient on warfarin interactions may never have received a single lecture on comparative pharmacology, veterinary pharmacotherapy, or the laws that govern drugs in food-producing animals.
A working definition
For the purposes of this guide, veterinary pharmacy can be defined as the provision of pharmaceutical care to non-human patients. That care includes selecting appropriate drug therapy, compounding preparations that do not exist commercially, monitoring therapeutic response, counselling pet owners, researching drug information, and reporting adverse drug events.
The term covers a wider territory than most people assume. It is not limited to a pharmacist in a white coat behind a veterinary hospital counter. It extends to community pharmacists dispensing a canine antibiotic, to industry scientists formulating a poultry vaccine, to regulators reviewing an adverse event report, and to poison control specialists answering a 2 a.m. call about a dog that ate rat bait.
Who veterinary pharmacists serve
A pharmacist with specialist veterinary training does not replace the veterinarian. They support the entire therapeutic chain — the community pharmacist who is unsure how to interpret a prescription, the veterinarian who needs a flavoured formulation that no manufacturer sells, and the pet owner who cannot get a tablet into a cat.
Specifically, trained veterinary pharmacists contribute to drug therapy selection, compounding, therapeutic monitoring, counselling of pet owners, drug information research, and adverse drug event reporting. Each of these is a skill set that community pharmacy already values — it simply needs to be redirected toward a different patient.
Why the training gap exists
The gap is historical, not accidental. For most of the twentieth century, veterinarians dispensed medications to pet owners themselves. They stocked the drugs, labelled the bottles and handed them over. Because pharmacists were not in the loop, pharmacy schools had no reason to teach veterinary content, and veterinary schools had no reason to teach students how to write prescriptions using standard Latin abbreviations.
That arrangement changed when human drugs began flowing into animal medicine in large volumes. Suddenly pharmacists were receiving prescriptions they had never been trained to interpret, for species they had never been trained to treat.
02Why veterinary pharmacy matters
Veterinary pharmacy is not a niche curiosity. It is a multi-billion dollar segment of healthcare with a documented record of preventable harm when pharmacists are undertrained.
The numbers
Veterinary drug sales were approximated at 76.4 billion dollars in 2010, according to the Animal Health Institute. In the same year, the American Veterinary Medical Association reported that approximately 31 percent of dog owners and 18 percent of cat owners had received prescriptions for medication from their pet's veterinarian.
What remains unknown is how many of those prescriptions were dispensed by pharmacists adequately trained in veterinary pharmacotherapy. That unknown is the problem.
The consequences of undertraining
Several published reports describe serious errors made by pharmacists when dispensing drugs to veterinary patients — some of which resulted in patient fatalities. Legal action has been directed at pharmacists because of dispensing errors. In a profession where a decimal point error can kill a 4 kg cat, the margin for improvisation is zero.
The argument made in the veterinary pharmacy literature is direct: adequate training of pharmacists in veterinary pharmacotherapy, as part of a core pharmacy curriculum, would prevent many dispensing errors. The pet-owning public demands and deserves high-quality medical care for their animals that does not stop abruptly at the pharmacy counter.
03The organisations behind the specialty
Veterinary pharmacy grew from a small group of hospital-based practitioners into a recognised specialty with its own colleges, certification pathways and academic societies. Four organisations in particular shaped that history.
Society of Veterinary Hospital Pharmacists (SVHP)
The SVHP is an organisation of pharmacists who work exclusively in the veterinary field, primarily at veterinary teaching hospitals within colleges of veterinary medicine. It represents the most established corner of the profession — the hospital pharmacist whose patients happen to be animals.
International College of Veterinary Pharmacy (ICVP)
In 2000, the SVHP established the International College of Veterinary Pharmacy to develop a recognised specialty college and a certification pathway for veterinary hospital pharmacy. The ICVP exists to turn informal expertise into a credential.
American Academy of Veterinary Pharmacology and Therapeutics (AAVPT)
Founded in 1977, the AAVPT consists of approximately 300 veterinary pharmacology-trained professionals drawn from more than 20 countries. Its members share a common interest in research and teaching in veterinary pharmacology. Where the SVHP focuses on practice, the AAVPT focuses on the science underneath it.
American College of Veterinary Clinical Pharmacology (ACVCP)
The ACVCP originated from the AAVPT in 1990 as an AVMA-recognised board specialty in veterinary clinical pharmacology. To achieve diplomate status, veterinarians must complete a residency, pass board examinations, and complete graduate training in veterinary clinical pharmacology.
The parallel is deliberate: the SVHP produced the ICVP for pharmacists, and the AAVPT produced the ACVCP for veterinarians. Both professions built their own credentialing ladders rather than sharing one.
04Where veterinary pharmacists work
The current scope of veterinary pharmacy practice includes veterinary academia, veterinary specialty referral centres, community and online pharmacies that serve veterinary patients only, the pharmaceutical and agricultural industry, and government public health and regulatory sectors. Some settings treat animals exclusively; others mix human and animal patients under one roof.
Veterinary teaching hospitals
The most well-established practice of veterinary pharmacy resides in veterinary teaching hospitals. Pharmacists in these roles provide expertise across three streams:
- Service — drug selection, distribution and control.
- Teaching — didactic instruction, incidental exchanges, client counselling, in-service education, and continuing education programmes for pharmacists and veterinarians.
- Research — clinical trial development and administration, quality assurance of compounded preparations, adverse drug reaction and medication error reporting, publication in scientific and professional journals, and responding to drug information queries.
Veterinary specialty referral centres
Many pharmacists are not aware that veterinary specialisation exists at all. Specialty training programmes, generally three years in length, and certification examinations exist in veterinary ophthalmology, oncology, anesthesiology, cardiology, neurology, surgery, dentistry and other disciplines.
Community veterinary pharmacies
One of the most rapidly growing areas of veterinary pharmacy practice is the community pharmacy setting. When the Animal Medicinal Drug Use Clarification Act (AMDUCA) of 1996 codified the extra-label use of human drugs in animals, veterinarians began prescribing more and more human drugs for animal patients. As a result, pharmacists in chain and independent pharmacies were presented with an unprecedented number of prescriptions for animals.
Pharmaceutical and agricultural industry
Pharmacists with veterinary expertise are valuable to the animal health industry. Their training uniquely combines pharmacological expertise, clinical decision-making and marketing skills — a combination that makes them effective professional representatives for veterinary pharmaceutical manufacturers.
Government and regulatory sectors
Veterinary pharmacists provide valuable services across government. The Center for Veterinary Medicine of the US Food and Drug Administration employs many veterinary pharmacists in compliance, surveillance, adverse event reporting and medication error prevention.
The Centers for Disease Control and Prevention employs veterinary pharmacists charged with overseeing the distribution and use of biological agents and drugs used to prevent or treat rare zoonotic diseases. The National Institutes of Health employs a veterinary pharmacist responsible for providing conventionally manufactured drugs, compounds and consultation for research animals in NIH-funded protocols.
That NIH role includes a welfare dimension that most pharmacists never consider: minimising the stress that drug administration causes to research animals. This involves developing combination dosage forms to avoid multiple administrations, and transmucosally absorbed drugs for nasal and buccal administration.
Disaster relief
Veterinary pharmacists may also serve on disaster relief teams. These specially trained pharmacists form part of multidisciplinary teams that may include veterinarians and veterinary technicians, ready to be deployed regionally. When called upon, these teams are sent to stricken areas to provide triage, medical care and treatment for displaced and injured animals.
One of the largest deployments of a Veterinary Medical Assistance Team occurred during the Hurricane Katrina recovery in 2005, and many veterinary pharmacists were involved in those efforts.
Animal poison prevention and consultation
Veterinary pharmacists may serve as poison control specialists at animal poison control centres such as the Pet Poison Helpline. Pharmacists are often the last line of defence in recognising and preventing potential animal poisoning.
The complication is that pharmacists are traditionally trained only in human toxicology, which can be vastly different from veterinary toxicology. A substance that is harmless to a human can be lethal to a dog, and vice versa.
05The two differences that drive everything
Veterinary pharmacy is not human pharmacy with a different species label. Two profound differences between human and animal patients drive most of the rules, regulations and practical considerations in the field.
Difference one: animals cannot speak
Animal patients do not communicate using spoken words. A human patient can telephone a prescriber and describe symptoms well enough to support a reasonable diagnosis. An animal patient cannot.
This single limitation is the reason the Veterinarian-Client-Patient Relationship (VCPR) exists. Because the animal cannot report its own history, the veterinarian must have either physically examined the animal or visited the site where the animal is housed before prescribing. The VCPR is not bureaucratic paperwork — it is a substitute for the history a human patient would provide verbally.
Difference two: animals become food
Animals and their byproducts are consumed as food by humans. Meat, milk, eggs, honey and many other food products come from livestock species such as cattle, swine, sheep, goats, chickens, turkeys, fish and honeybees.
Animal byproducts — fur, skin, bone meal, manure, hooves, horns, blood, internal organs and beeswax — are used extensively in hundreds of other products used by humans. Because the use of animal tissues in human foods and products is so widespread, great care must be taken to avoid residues caused by drug administration to animals.
Regulations for food-producing animals
Regulations for human drugs and for drugs intended for food-producing animals differ in important ways precisely because humans may consume animal tissues and byproducts. Withdrawal periods, residue limits and prohibited substances exist to protect the human food chain, not just the animal.
Regulations for companion animals: AMDUCA
In 1996, a milestone veterinary drug law was enacted. AMDUCA — the Animal Medicinal Drug Use Clarification Act — permitted extra-label drug use in animals under defined conditions. Extra-label use means using an approved drug in a manner not described on its label: a different species, a different indication, a different dose, a different route or a different frequency.
AMDUCA is the legal foundation for a large share of modern veterinary prescribing, and it is the reason community pharmacists began seeing human-labelled medicines on animal prescriptions.
Prescription (legend) drugs and the VCPR
Prescription animal drugs, also known as legend drugs, are restricted by federal law to use by or on the order of a licensed veterinarian, according to Section 503(f) of the Food, Drug and Cosmetic Act.
The law requires that such drugs be labelled with the statement: "Caution: Federal law restricts this drug to use by or on the order of a licensed veterinarian" — within the confines of a VCPR. A pharmacist dispensing a legend veterinary drug without a valid VCPR is dispensing outside the law.
06Veterinary terminology: the abbreviations that kill
Veterinary medical terminology is largely grounded in the same Latin system that applies to human medicine. However, significant differences have developed between the two, and those differences have produced documented fatalities.
Why the divergence happened
Until recently, veterinarians almost exclusively dispensed medications to pet owners themselves. They had no need to learn to write prescriptions properly, because no pharmacist was reading them. Consequently, many veterinary colleges did not teach veterinary students how to write prescriptions using standard Latin abbreviations.
The result is that non-veterinary-trained pharmacists frequently misinterpret unknown veterinary abbreviations.
"Once daily" is almost exclusively abbreviated as SID (semel in die) by veterinary prescribers. Pharmacists have misinterpreted this abbreviation to read TID, QID, and even 5/D — usually resulting in serious toxicity, and in some cases death.
This is not a theoretical risk. It is the single clearest argument for teaching veterinary terminology in pharmacy school.
Common veterinary abbreviations
- Bolus — Large, solid, oral dosage form, usually for horses or livestock.
- Divided BID — The total daily dose is calculated and then administered over 2 equally divided doses 12 hours apart.
- DLH — Domestic Longhaired (cat).
- Drench — Large volume of oral liquid administered as a single dose (usually livestock).
- DSH — Domestic Shorthaired (cat).
- EOD — Every other day.
- Fe — Feline, or cat.
- FS or F/S — Female spayed.
- Intact — A non-neutered animal.
- K9 — Canine, or dog.
- MC or M/C — Male castrated.
- MN or M/N — Male neutered.
- OD — Once daily, or right eye, depending on context.
- Paste — Viscous oral liquid dosage form (frequently for horses).
- Pinnae — The inner, hairless part of an animal's ears.
- QOD — Every other day.
- SID — Semel in die (once daily).
- TD — Transdermal.
Notice how many of these have no human-medicine equivalent at all. DLH, DSH, K9, Fe, intact, pinnae — these describe anatomy and husbandry, not just dosing. A pharmacist who does not know them is reading a foreign language.
07Agrochemicals and animal agriculture
An agrochemical is any substance that humans use to help in the management of an agricultural ecosystem. The category includes fertilizers, liming and acidifying agents, soil conditioners, pesticides, and chemicals used in the raising of livestock such as antibiotics and hormones.
The use of agrochemicals is an increasingly prominent aspect of modern agriculture. As farms have become massive in size, the challenges in keeping crops free of damage have increased. Hand-tilling weeds has become impractical. Agrochemicals have therefore become widely used.
Their use has been critically important in increasing the yield of agricultural crops. However, some uses cause environmental and ecological damage, which detracts significantly from the benefits gained.
Fertilizers
Fertilizers are substances added to agricultural lands to alleviate nutrient deficiencies, allowing large increases in the rates of crop growth. As of 2006, over 150 million tons of fertilizer were used in agriculture each year worldwide.
In the United States, the average rate of fertilizer application is about 220 pounds per 2.5 acres — approximately 100 kilograms per hectare — and about 21 million tons are used in total each year.
The most commonly used fertilizers are inorganic compounds of nitrogen. Where agricultural plants have access to sufficient water, their productivity is most often constrained by the supply of available forms of nitrogen, especially nitrate (NO3-) and sometimes ammonium (NH4+).
Farmers commonly increase the availability of these inorganic forms of nitrogen by applying suitable fertilizers such as urea or ammonium nitrate. The rate of fertilization in intensive agricultural systems is commonly several hundred pounds of nitrogen per acre per year.
Phosphorus and potassium are other commonly applied nutrients. Most phosphorus fertilizers are manufactured from rock phosphate, and are known as superphosphate and triple-superphosphate. Some other phosphorus fertilizers are made from bone meal or seabird guano. Potassium fertilizers are mostly manufactured from mined potash.
Often these three macronutrients are applied in a combined formulation that includes nitrogen, known as an N-P-K fertilizer. For example, a 10-10-10 fertilizer contains materials equivalent to 10 percent each of nitrogen, P2O5 (the source of phosphorus) and K2O (the source of potassium), while a 4-8-16 fertilizer contains these nutrients at 4 percent, 8 percent and 16 percent respectively. The desired ratios are governed by the qualities of the soil being fertilized and by the needs of the specific crop.
Sometimes other nutrients must also be supplied. Sulfur, calcium or magnesium, for example, are limiting to crop productivity in some places. Rarely, micronutrients such as copper, molybdenum or zinc must be applied to achieve optimum crop growth.
Liming and acidifying agents
Agricultural soils are commonly too acidic or too alkaline for the optimal growth of many crop species. When this is the case, chemicals may be added to the soil to adjust its pH to a more appropriate range.
Acidic soils are an especially common problem. Acidic soil can be caused by various factors, including the removal of acid-neutralising bases contained in the biomass of harvested crops, the use of certain types of fertilizers, acid rain, the oxidation of sulfide minerals, and the presence of certain types of organic matter in soil.
Because soil acidification is such a common occurrence, acid-neutralising (liming) materials are among the most important agrochemicals used, in terms of the quantities added to soil each year.
Acidic soils are commonly neutralised by adding calcium-containing minerals, usually calcite (CaCO3) in the form of powdered limestone or crushed oyster or mussel shells. Alternatively, soil acidity may be neutralised using faster-acting lime, Ca(OH)2.
The rate of application of acid-neutralising substances can vary greatly, from several hundred pounds per acre per year to more than 1,000 pounds per acre per year. The rates used depend on the acidity of the soil, the rate at which new acidity is generated, and the needs of specific crops.
Much less commonly, soils may be alkaline and may have to be acidified to bring them into a pH range suitable for most crops. This problem can be especially common in soils developed from parent materials having large amounts of limestone (CaCO3) or dolomite (CaMg(CO3)2). Soil can be acidified by adding sulfur compounds, which generate acidity as they are oxidized, or by adding certain types of acidic organic matter such as peat mined from bogs.
Soil conditioners
Soil conditioners are organic-rich materials sometimes added to soils to improve aeration and water-holding capacity, both of which are very important aspects of soil quality.
Various materials can be used, including peat, crop residues, livestock manure, sewage sludge and even shredded newspapers. However, compost is the most desirable of the soil conditioners. Compost contains large quantities of well-humidified organic compounds, and also supplies the soil with nutrients in the form of slow-release organic compounds.
Pesticides
Pesticides are agrochemicals used to reduce the abundance of pests — organisms considered to interfere with some human purpose. Many kinds are used in agriculture, but they can be categorised on the basis of the sorts of pests targeted.
- Herbicides — used to kill weeds, non-desired plants that interfere with crop growth and reduce yield.
- Fungicides — used to protect agricultural plants from fungal pathogens, which can sometimes cause complete crop failure.
- Insecticides — used to kill insects that defoliate crops, or that feed on stored grains or other agricultural products.
- Acaricides (miticides) — used to kill mites, which are pests of crops such as apples, and ticks, which can carry debilitating diseases of livestock.
- Nematicides — used to kill nematodes, parasites of the roots of some crop species.
- Rodenticides — used to kill rats, mice, gophers and other rodents that are field pests or that eat stored crops.
- Preservatives — agrochemicals added to processed foods to help prevent spoilage.
Pesticides are chemically diverse substances. About 300 different insecticides are in use, along with about 290 herbicides, 165 fungicides and other pesticides. However, each specific pesticidal chemical — the active ingredient — may be marketed in a variety of formulations containing additional substances that increase efficacy.
These so-called inert ingredients of the formulation can include solvents, detergents, emulsifiers and chemicals that allow the active ingredient to adhere better to foliage. In total, more than 3,000 different pesticide formulations exist.
Classification by chemical structure
Inorganic pesticides are simple compounds of toxic elements such as arsenic, copper, lead and mercury. They were formerly used in large quantities, especially as fungicides, but have largely been replaced by organic pesticides.
A few commonly used organic pesticides are based on substances that plants synthesise naturally as biochemical defences. Pyrethrin, for example, is an insecticide based on pyrethrum, obtained from a species of chrysanthemum, while rotenone is a rodenticide extracted from a tropical shrub.
Most organic pesticides, however, have been synthesised by chemists. The synthetic organic pesticides include well-known groups such as the chlorinated hydrocarbons (including the insecticide DDT and the herbicides 2,4-D and 2,4,5-T), organophosphates (such as parathion and malathion), carbamates (for example carbaryl and carbofuran), and triazine herbicides (such as atrazine and simazine).
A final class is based on the action of bacteria, fungi or viruses that are pathogenic to specific pests and can be applied as a pesticidal formulation. The most commonly used biological insecticide is manufactured using spores of the bacterium Bacillus thuringiensis, also known as Bt. These spores can be mass-produced in laboratory-like factories and then used to prepare an insecticidal solution.
Insecticides containing Bt are mostly used against leaf-eating moths, biting flies such as blackflies, and mosquitoes. Most other insects are little affected by Bt-based insecticides, so the unintended non-target effects of their usage are relatively small.
Agrochemicals used for animal husbandry
Contagious diseases of livestock can be a problem in modern agriculture, especially when animals are reared at high density — for example, in feed-lots. Various agrochemicals may be used to control infectious diseases and parasites under such conditions.
Antibiotics are especially important in this respect. These chemicals may be administered by injection whenever bacterial diseases are diagnosed. However, antibiotics are sometimes administered with the feed as a prophylactic treatment to prevent the occurrence of infections.
Because of the extremely crowded conditions when livestock are reared in factory farms, antibiotics must be administered routinely to animals raised under those circumstances. This practice is contentious, as evidence suggests that the development of antibiotic-resistant bacteria may be encouraged.
Sometimes hormones and other animal-growth regulators are used to increase the productivity of livestock. For example, bovine growth hormone is routinely administered in some agricultural systems to increase the growth rates of cows and their milk production. This use is also contentious; critics contend that the unclear health effect of the hormone in humans argues against growth hormone supplementation.
Environmental effects
Many important benefits are achieved by the use of agrochemicals. These are largely associated with increased yields of plant and animal crops, and less spoilage during storage. In combination with genetically improved varieties of crop species, agrochemicals have made important contributions to the successes of the green revolution, helping to increase the food supply for a rapidly increasing human population.
However, the use of certain agrochemicals has also been associated with important environmental and ecological damage.
Nitrate contamination and eutrophication
Excessive use of fertilizers can lead to contamination of groundwater with nitrate, rendering it unfit for consumption by humans or livestock. Water containing large concentrations of nitrate can poison animals by immobilising some of the haemoglobin in blood, reducing the ability to transport oxygen.
In addition, the runoff of agricultural fertilizer into streams, lakes and other surface waters can cause increased productivity of those aquatic ecosystems — a problem known as eutrophication. The ecological effects can include extensive mortality of fish and other aquatic animals, excessive growth of nuisance algae, and an off-taste in drinking water.
Non-target exposure and drift
The use of pesticides can also result in environmental problems. Pesticides are used to reduce target pest populations below an economically determined level of acceptable damage. Unfortunately, during many uses of pesticides in agriculture, the exposure of other organisms — including humans — is not well controlled.
This is especially true when entire fields are sprayed, for example when using application equipment drawn by a tractor, or mounted on an airplane or helicopter. During these sorts of broadcast applications, many non-target organisms are exposed to the pesticide. This occurs on the treated site, and also on nearby off-sites as a result of drift of the sprayed agrochemical.
08Improving patient compliance
Compliance is a real issue for far too many veterinarians and pet owners. Many pet owners do not realise the dangers and consequences of abandoning or interrupting treatment, and most are not aware of other options that could make administering medications more pleasant for them and their pets. When they become frustrated, they may simply take their business elsewhere.
When non-compliance results in lost business, it can cost a practice more than it realises.
The numbers behind non-compliance
- The rate of compliance for chronic medication is just 76 percent. That means 24 percent of pets are not being treated with the medications they need to live healthy lives — and in some cases, simply to live.
- Pet owners who are shown one or more ways to administer medication had a significantly higher rate of compliance: 74 percent versus 59 percent for those not shown.
- Yet only 43 percent of practices show pet owners how to administer medication.
- 60 percent of owners would pay more for medication that is palatable or easy to administer.
- 93 percent of veterinarians say that compliance monitoring has a positive impact on their practice.
- 72 percent of pet owners would like to receive information in writing about their pets' medication so they could refer back to it.
Eight ways to make non-compliance a non-issue
- Give pet owners information about the dangers of non-compliance.
- Give pet owners simple, detailed instructions and easy administration techniques.
- Prescribe medications that taste better.
- Prescribe medications that are smaller and easier to administer.
- Prescribe medications that are more affordable, when possible.
- Provide automated refill reminders.
- Make it easier, safer and more convenient for pet owners to get the medications they need.
- When compliance is an issue, provide unique, proprietary dosage forms designed to promote it.
Compliance-focused dosage forms
A whole category of veterinary formulations exists purely to solve the adherence problem. These are the tools a compounding-aware practice keeps in its toolkit.
- Bitter-Block — Using a proprietary process and food-grade materials, each particle of medication is coated before it is pressed into a tasty, chewable tablet. The soluble, temporary coating protects the taste buds from the bitterness of the medication while allowing the flavour to do its job.
- Gourmet chewable tablets — Available in natural chicken and fish flavours for dogs and cats, and apple-molasses, peppermint and alfalfa flavours for horses.
- Low-Dust Granules — Compounded granules help reduce the risk of chemical exposure compared with powders. The amount of dust produced when administering the preparation is reduced, decreasing exposure risk.
- Medi-Melts — Look like standard tablets but are lightly compressed so they disintegrate rapidly on an animal's tongue, creating a paste that cannot be rejected. For sicker animals that may have difficulty swallowing, or animals that reject any medication, this can be the perfect solution — and the tasty flavour makes it seem like a treat.
- Medi-Mints — Mint-flavoured tablets for horses.
- Polox-A-Gel — Stores as a liquid while refrigerated, and resolves into a gel at room or body temperature so the preparation stays on the patient longer.
- Quad-Tabs — Up to four doses from each tablet.
- Tiny Tabs — Tiny, compressed tablets, ideal for difficult-to-administer or bitter-tasting medications.
- Twist-a-Dose — For when oral medications fail and simple, accurate dosing is needed every time; a different twist on oral gel applications.
09Dosage form considerations
Pharmaceutical dosage forms contain both pharmacologically active compounds and excipients. For any given product, its quality and performance will be a function of the physicochemical properties of the active pharmaceutical ingredient, the excipients, and the manufacturing process.
APIs are formed into dosage-form products before they are dispensed or administered to animals. The API is mixed with excipients such as binders, fillers, flavouring and bulking agents, preservatives and antioxidants. These ingredients may be dried, milled, blended, compressed and granulated to achieve the desired properties before they are manufactured as a final formulation.
Common veterinary dosage forms
Each dosage form is tailored to meet the needs of the specific animal species, the disease condition (for example, intramammary), the therapeutic goal (for example, intervaginal implants for estrus control), and the conditions of use — in hospital, at home, or as mass herd treatment.
Oral
- Tablets
- Capsules
- Powder
- Granules
- Premix
- Medicated blocks
- Solutions
- Suspensions
- Emulsions
- Pastes
Parenteral
- Solutions
- Suspensions
- Micro/nano emulsions
- Liposomes
- In situ forming gels/suspensions
- Implants
Topical
- Solution
- Suspensions
- Suspoemulsion
- Pastes
- Ointments
- Cream
- Lotions
- Gel
- Transdermal patches
- Dusting powder
Special dosage forms
- Recombinant proteins and peptides
- Vaccines
- Inhaled
- Intramammary infusion products
- Intervaginal delivery system
10Veterinary drug compounding
Compounding is one of the most important — and most legally sensitive — areas of veterinary pharmacy. It is also the area where pharmacists add the most direct clinical value, because it is the point at which an unsuitable commercial product is transformed into something an animal will actually take.
Terminology
Terminology to describe the extemporaneous preparation of medicines varies widely across the global community. The practice may be referred to as extemporaneous manufacturing, extemporaneous preparation, extemporaneous compounding, or simply compounding, depending on the national directives of individual countries.
The United States Pharmacopeia defines compounding as "the preparation, mixing, assembling, altering, packaging, and labeling of a drug, drug delivery device, or device in accordance with a licensed practitioner's prescription, medication order, or initiative based on the practitioner/patient/pharmacist/compounder relationship in the course of professional practice."
The USP definition does not distinguish compounding for humans from compounding for animals. The only government that appears to specifically address compounding for animals is New Zealand, which defines it as "a means to make up, prepare, produce, or process a veterinary medicine into a preparation for treatment of animals under the care of the compounding veterinarian."
The American Veterinary Medical Association aligns its definition with the FDA Center for Veterinary Medicine's Extra Label Drug Use Guidance, stating that compounding is the "customized manipulation of an approved drug(s) by a veterinarian, or by a pharmacist upon the prescription of a veterinarian, to meet the needs of a particular patient."
In practical terms: compounding is the process by which a veterinarian or pharmacist prepares a medication in a manner not stipulated in the product labelling, to create a compound specifically tailored to the needs of an individual patient.
Why compounding is necessary in veterinary medicine
Compared with the number of drugs approved by the FDA for use in humans, the number of drugs approved for use in veterinary species is low. The need for compounded therapies to treat animals is consequently high.
Even though current federal law permits veterinarians to use and prescribe drugs that are FDA-approved for human use in an extra-label fashion, many human medications are only available in formulations that are impractical or unsafe for use in pets — the use of xylitol as an artificial sweetener is the classic example, since xylitol is severely toxic to dogs.
Compounding also allows access to medications that are not currently commercially available. This includes drugs discontinued by pharmaceutical companies for economic reasons, or as a result of voluntarily or federally mandated withdrawals — cisapride, potassium bromide and diethylstilbestrol are examples — and drugs unavailable for use due to temporary shortages, such as electrolytes and fluids, and opioid injections.
Potential benefits of compounded drugs
- Compounded medications provide treatment options for animal patients when no suitable government-approved drugs are available.
- Approved products may be available in flavours that certain animal species will not accept — citrus and sweetly flavoured human paediatric medicines, for example, are not accepted by cats.
- Compounding can modify an approved product into an acceptable dosage form or flavour to increase adherence in an individual patient, particularly in species that are difficult to medicate, such as cats and exotic or wild animal species.
- Beyond optimising formulations, compounded preparations can provide therapeutic options when no approved drugs exist — for either humans or animals — for a given indication. Cisapride, a prokinetic, was withdrawn from the US human market for safety reasons in 2000, but it is considered the best available treatment option for non-obstructive chronic constipation or megacolon in cats.
Risks associated with compounded drugs
The risk of serious harm, including therapeutic failure, from compounded preparations is significant and well established. Three examples illustrate the stakes.
- The deaths of 64 humans from contaminated sterile compounds in the USA in 2012, which prompted sweeping regulatory oversight for compounds prepared for humans through the Drug Quality and Security Act of 2013.
- The deaths of 21 polo ponies in Florida from a 10-fold overdose of selenium in a compounded drug product.
- The ongoing risk of poor quality — contaminants, impurities and incorrect strength — together with unknown bioavailability and unknown stability, leading to therapeutic failure. These compounded mimics may increase overall costs to the pet owner due to lack of clinical response or overt toxicity.
Compounding for food-producing animals
Meat, milk, eggs, honey and many other food products come from livestock species such as cattle, swine, sheep, goats, chickens, turkeys, fish and honeybees. Animal byproducts — fur, skin, bone meal, manure, hooves, horns, blood, internal organs and beeswax — are used extensively in hundreds of other products used by humans.
Because the use of animal tissues in human foods and products is so widespread, great care must be taken to avoid residues caused by drug administration to animals. Compounding for food-producing species therefore carries additional regulatory weight.
Compounding controlled substances
While compounding of controlled substances is permitted under federal compounding law, there are additional federal requirements that must be followed. In addition to FDA regulations, prescribing and dispensing must comply with Drug Enforcement Administration rules and with all pertinent state controlled substances laws.
Pharmacists are strongly advised to familiarise themselves with these regulations to avoid violating DEA controlled substance laws.
Pharmacies compounding controlled substances for office use must register with the DEA as a controlled substance manufacturer. Pharmacies compounding controlled substances for individual patients do not have to register as a manufacturer, but must dispense the product directly to the client and may not send the controlled substances to the veterinary practice for dispensing.
For example, a prescription for compounded tramadol oral suspension must be written for an individual patient and dispensed to that patient's owner.
Quality standards for compounded drugs
USP standards take two overarching forms: monographs and general chapters.
Monographs provide standards for identity, quality, purity, strength, packaging and labelling for bulk substances, drug products, compounded preparations and other ingredients used by the pharmaceutical industry and compounding practitioners.
USP compounded preparation monographs are verified formulas and processes that allow compounders to prepare compounded drug preparations of known purity, strength, quality and stability. They are named by the USP nomenclature convention, which consists of the generic drug name, the word "Compounded," the dosage form, and the word "Veterinary" if the preparation is for veterinary use only — for example, "Enrofloxacin, Compounded, Oral Suspension, Veterinary."
General chapter nomenclature
General chapter nomenclature is designated by a number in angle brackets next to the italicised name of the chapter, for example <797> Pharmaceutical Compounding — Sterile Preparations.
- Below <1000> — mandatory and enforceable by regulatory authorities such as the FDA and Boards of Pharmacy.
- Above <1000> — interpretive, intended to provide information on, give definition to, or describe best practices for a subject.
- If a below-<1000> general chapter cites an above-<1000> chapter, the informational chapter may then become enforceable in that context.
Mandatory general chapters typically describe general processes, methods, tests, assays and other requirements applicable to the articles described in USP monographs, while informational chapters do not contain mandatory methods, tests, assays or requirements.
Quality assurance and beyond-use dates
USP compounded preparation monographs provide exact instructions for mixing exact quantities of known substances to produce a compound of known purity, identity, quality and strength over the designated beyond-use date (BUD).
To ensure the preparation maintains these characteristics, USP compounded preparation monographs require specific tests for pharmacists to perform on each finished compound. Tests to determine pH, content uniformity of dosage units, endotoxin and sterility all provide quality assurance for finished compounds and allow the compounder to assign the BUD in the monograph.
For compounds that do not have a USP compounded preparation monograph, the same tests can be performed to determine compound quality. Extending the BUD for a non-monographed compound beyond USP defaults requires consideration of five types of stability: chemical, physical, microbiological, therapeutic and toxicological. Chemical, physical and toxicological stability can only truly be determined by stability-indicating methods.
Owner counselling points for compounded veterinary drugs
- Emphasise that the medication is a compounded preparation, and explain its limitations compared with an FDA-approved product.
- Review the drug name, indication and route of administration.
- Review frequency of administration and duration of therapy.
- Demonstrate administration devices and accurate dose markings for each drug.
- Discuss storage and handling of the medication, including any caregiver precautions.
- Describe proper disposal of unused compounded drug.
- Emphasise observation of the compounded drug for any change in physical characteristics — colour, consistency or odour — or pet refusal to take the drug after initial acceptance.
- Inform the caregiver of any drugs or foods to avoid, and remind them to check for any performance drug rules for animal athletes.
- Emphasise the importance of returning to the veterinarian for the recheck appointment.
- Describe monitoring signs for efficacy, or lack thereof, and toxicity including allergic reactions, and advise the owner to contact the veterinarian immediately if these are noticed.
Adverse event reporting for compounded drugs
Community pharmacists are often the first healthcare providers to recognise or suspect adverse drug events related to compounded drugs. As a result, they can play a valuable role in collecting, investigating and reporting this information to the prescribing veterinarian and/or the FDA Adverse Event Reporting System.
Adverse events resulting from compounded drugs are often caused by poor compound quality. They may manifest in three broad ways:
- Lack of expected therapeutic response — from sub-potent, unstable or non-bioavailable compounds.
- A new unexpected symptom or behaviour — rash, swelling, hyper-salivation, sneezing, vomiting or diarrhoea.
- Symptoms of toxicity — from super-potent compounds or species-specific toxic excipients.
11Key takeaways
Veterinary pharmacy rewards a pharmacist who is willing to learn a second language, a second legal framework and a second pharmacology. The following points summarise the field at a glance.
- Pharmacists are the only healthcare professionals legally permitted and socially expected to provide pharmaceutical care to all species — yet most receive no formal veterinary training.
- Veterinary drug sales ran to approximately 76.4 billion dollars in 2010, and roughly a third of dog owners and a fifth of cat owners received prescriptions that year.
- Documented dispensing errors, some fatal, have resulted from pharmacists misreading veterinary abbreviations — most notoriously SID being read as TID or QID.
- Four organisations anchor the specialty: the SVHP, the ICVP, the AAVPT and the ACVCP.
- Practice settings span teaching hospitals, referral centres, community pharmacies, industry, government and disaster relief teams.
- Two differences drive everything: animals cannot speak, and animals become food. The first creates the VCPR; the second creates residue and withdrawal rules.
- AMDUCA 1996 legalised extra-label drug use in animals and pushed human medicines onto veterinary prescriptions.
- Agrochemicals — fertilizers, liming agents, soil conditioners, pesticides and husbandry drugs — underpin modern agriculture, with real environmental costs including nitrate contamination, eutrophication and spray drift.
- Non-compliance affects roughly a quarter of pets on chronic medication; flavoured, smaller, easier dosage forms and owner education measurably improve adherence.
- Compounding fills the gap left by a small veterinary drug market, but carries well-documented risks — 64 human deaths in 2012 and 21 polo pony deaths from a selenium overdose are the cautionary examples.
- USP monographs and general chapters provide the quality framework; below-<1000> chapters are enforceable, above-<1000> chapters are interpretive.
- Community pharmacists are often the first to spot a compounded-drug adverse event, and reporting it is part of the job.
This article is published for educational and informational purposes only. It is not veterinary advice and does not create a veterinarian-client-patient relationship. Never start, stop, change or combine any medicine for an animal based solely on information read online. Always consult a licensed veterinarian for the diagnosis and treatment of any animal.
12Authoritative resources
For verified drug, regulatory and safety information, readers should consult official sources rather than secondary summaries.
13About this article
This article is an editorial adaptation of a 2023 veterinary pharmacy lecture note prepared for pharmacy students and healthcare learners. It has been restructured, expanded and formatted for online reading, with beginner-to-advanced explanations added throughout.
Corrections, content concerns, study questions and general enquiries can be directed to this address.
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