Oxfendazole

Oxfendazole is a broad-spectrum benzimidazole anthelmintic medication widely utilized in avian medicine for the treatment and control of internal parasitic infections, particularly those caused by roundworms and other nematodes. This medication belongs to the benzimidazole class of antiparasitic drugs, which are considered among the most effective and commonly prescribed dewormers in veterinary practice. Oxfendazole has gained significant acceptance in avian medicine due to its efficacy against a wide range of gastrointestinal parasites that commonly affect pet birds, poultry, and aviary collections. When administered under proper veterinary supervision, oxfendazole provides reliable parasite control with a favorable safety profile in most avian species.

The mechanism of action of oxfendazole involves interference with the parasite's energy metabolism at the cellular level. Specifically, this medication binds to beta-tubulin proteins within the parasitic worms, disrupting microtubule formation and function. This disruption prevents the parasites from properly absorbing glucose and other essential nutrients, effectively starving them and inhibiting their ability to maintain cellular structures. The impaired energy metabolism leads to immobilization and eventual death of the parasites, which are then expelled from the bird's gastrointestinal tract through normal digestive processes. This targeted mechanism makes oxfendazole highly effective while minimizing impact on the host bird's own cellular functions.

Oxfendazole is available in several formulations suitable for avian administration, including oral suspensions, pastes, and powders that can be mixed with food or water. The oral route of administration is standard for this medication, making it relatively convenient to administer to birds compared to injectable antiparasitics. However, medicating birds can present unique challenges due to their small size, sensitive nature, and tendency to refuse unfamiliar foods or medications. Avian veterinarians may recommend specific administration techniques based on the species being treated and the severity of the parasitic infection. Compounded formulations may be necessary for very small bird species to ensure accurate dosing.

The safety profile of oxfendazole in birds is generally favorable when the medication is used according to veterinary guidance and at appropriate dosages. Like all benzimidazole anthelmintics, oxfendazole requires careful attention to dosing, as the therapeutic window can vary between species and individual birds. Avian veterinary supervision is essential when using this medication, as accurate diagnosis of parasitic infection through fecal examination should precede treatment. Proper dosing based on accurate body weight is critical given the significant size variation among bird species, ranging from small finches to large macaws. Completing the full prescribed treatment course is important to ensure complete elimination of parasites and reduce the risk of resistance development.

The primary indication for oxfendazole in avian medicine is the treatment of gastrointestinal nematode infections, commonly known as roundworm infestations. Roundworms represent one of the most prevalent parasitic infections affecting birds, particularly those housed in outdoor aviaries, those with access to soil or ground environments, and newly acquired birds from unknown backgrounds. These parasitic infections can cause significant health problems in birds, including weight loss, poor feather condition, decreased appetite, and in severe cases, intestinal obstruction or death. Oxfendazole is considered a first-line treatment option for roundworm infections due to its broad-spectrum activity and established efficacy across multiple avian species.

Oxfendazole demonstrates excellent efficacy against several specific nematode species that commonly parasitize birds. Ascaridia species, which are large roundworms found in the small intestine of various bird species, are particularly susceptible to oxfendazole treatment. These parasites can grow several centimeters in length and cause significant intestinal damage and nutritional deficiencies in affected birds. Capillaria species, also known as threadworms or hairworms, represent another important target for oxfendazole therapy. These thin, hair-like worms can infect various portions of the digestive tract and cause severe inflammation and tissue damage. Heterakis gallinarum, the cecal worm found primarily in gallinaceous birds, is also effectively treated with oxfendazole.

Beyond the primary roundworm indications, oxfendazole may be prescribed for other parasitic conditions in birds as part of a comprehensive deworming protocol. Some avian veterinarians utilize oxfendazole in combination with other antiparasitic medications to address mixed infections involving multiple parasite types. The medication may also be used prophylactically in certain situations, such as when integrating new birds into an established flock or as part of routine health management in breeding facilities. However, prophylactic use should always be guided by veterinary recommendation and ideally confirmed by fecal testing to avoid unnecessary medication exposure.

Oxfendazole may also demonstrate activity against certain other internal parasites beyond roundworms, including some tapeworm species and gapeworms in certain circumstances. However, its efficacy against these parasites may be less consistent than against nematodes, and alternative medications may be preferred for these specific infections. Avian veterinarians select oxfendazole for treatment based on diagnostic findings, the specific parasite species identified, the bird species being treated, and the overall health status of the patient. The decision to use oxfendazole versus alternative anthelmintics depends on multiple factors including previous treatment history and potential resistance concerns.

When selecting oxfendazole for parasite treatment, avian veterinarians consider several factors that influence its appropriateness for individual patients. The medication's oral administration route makes it suitable for birds that can be medicated through food or water, or through direct oral dosing. Its broad-spectrum activity is advantageous when multiple nematode species are suspected or confirmed. Oxfendazole may be preferred in situations where other benzimidazoles have shown reduced efficacy, or when its specific pharmacokinetic properties are better suited to the treatment protocol. Cost considerations and medication availability may also influence the choice between oxfendazole and alternative anthelmintics in avian practice.

The dosing protocol for oxfendazole in avian patients requires careful individualization based on the specific bird species, body weight, severity of infection, and overall health status. Avian veterinarians determine the exact dose for each patient, as inappropriate dosing can result in treatment failure or potential toxicity. Weight-based dosing is absolutely critical in birds due to the enormous variation in body size across species, from tiny finches weighing just a few grams to large macaws weighing over a kilogram. Accurate weight measurement using a gram scale immediately before treatment is essential for calculating the appropriate dose. Species-specific metabolic differences may also influence dosing recommendations, as some birds metabolize medications differently than others.

General dosing guidelines for oxfendazole in birds typically fall within the range of 10 to 40 milligrams per kilogram of body weight, though the specific dose varies based on the target parasite and bird species. Some treatment protocols recommend a single dose, while others may require multiple doses administered over several days to ensure complete parasite elimination. Loading doses are generally not required for oxfendazole, though repeat treatments may be scheduled to address different life stages of the parasites. The frequency of administration depends on the treatment protocol selected by the avian veterinarian, with some protocols calling for daily dosing for three to five consecutive days.

Treatment duration with oxfendazole varies depending on the type and severity of parasitic infection being addressed. Single-dose protocols may be effective for mild infections with susceptible parasites, while more severe or chronic infestations often require extended treatment courses. Many avian veterinarians recommend follow-up fecal examinations approximately two to three weeks after treatment to confirm successful parasite elimination. Repeat treatment may be necessary if parasites are still detected on follow-up testing. The environmental contamination cycle of many avian parasites means that reinfection is possible, and environmental management strategies should accompany medical treatment.

Administration of oxfendazole to birds can be accomplished through several methods depending on the formulation used and the individual bird's temperament. Direct oral administration using a syringe or dropper allows for precise dosing and ensures the bird receives the full medication dose. This method requires gentle restraint and careful technique to avoid aspiration or injury to the bird. Mixing medication with a small amount of favored food can be effective for birds that readily accept treats, though this method carries some risk of incomplete dosing if the bird does not consume all the medicated food. Water medication is possible with some formulations but may result in variable dosing based on individual water consumption.

If a dose of oxfendazole is missed during a multi-day treatment protocol, bird owners should contact their avian veterinarian for guidance on how to proceed. In general, the missed dose should be given as soon as it is remembered, unless it is nearly time for the next scheduled dose. Doubling up on doses to make up for missed medication is never recommended, as this can increase the risk of adverse effects. If multiple doses are missed, the treatment course may need to be restarted or extended based on veterinary guidance. Consistency in medication timing helps maintain effective drug levels and optimizes treatment outcomes.

Completing the full prescribed course of oxfendazole treatment is essential for successful parasite elimination and prevention of resistance development. Even if the bird appears to improve clinically before the treatment course is finished, stopping medication early can allow surviving parasites to recover and potentially develop resistance to the medication. Antiparasitic resistance is an increasing concern in veterinary medicine, and responsible medication use helps preserve the effectiveness of available treatments. Bird owners should maintain communication with their avian veterinarian throughout the treatment period and report any concerns or adverse effects promptly. Follow-up fecal testing as recommended confirms treatment success and guides decisions about any additional therapy needed.

Oxfendazole is generally well-tolerated by most avian species when administered at appropriate doses under veterinary supervision. The benzimidazole class of anthelmintics has a relatively wide safety margin in birds compared to some other antiparasitic medication classes. Most birds complete their treatment course without experiencing significant adverse effects, particularly when the medication is dosed correctly based on accurate body weight. However, as with any medication, side effects can occur, and bird owners should be aware of potential reactions to monitor during treatment. Individual sensitivity can vary, and some birds may experience effects that others do not.

The most commonly observed side effects of oxfendazole in birds involve the gastrointestinal system and are typically mild and transient. Some birds may experience temporary changes in appetite, either decreased interest in food or occasionally increased hunger. Changes in droppings may occur, including alterations in color, consistency, or frequency of defecation. Mild regurgitation has been reported in some birds, particularly if the medication causes mild stomach upset. These gastrointestinal effects usually resolve within a day or two of treatment completion and do not typically require medical intervention. Ensuring the bird remains hydrated and continues to eat during treatment helps minimize these effects.

Moderate side effects are less common but may occur in some birds, particularly at higher doses or in sensitive individuals. Transient lethargy or decreased activity levels have been reported during treatment, though birds typically return to normal behavior within a few days. Some birds may show signs of mild neurological effects such as temporary loss of coordination or balance disturbances, though this is uncommon at standard therapeutic doses. Liver enzyme elevations have been documented with benzimidazole use in some species, though clinically significant hepatotoxicity is rare. Birds showing prolonged lethargy, persistent appetite loss, or concerning behavioral changes should be evaluated by an avian veterinarian promptly.

Serious side effects from oxfendazole are rare but require immediate veterinary attention if they occur. Severe allergic reactions, while uncommon, can manifest as difficulty breathing, severe swelling, or collapse. Signs of acute toxicity may include severe neurological symptoms such as tremors, seizures, or profound weakness. Bone marrow suppression has been associated with prolonged or high-dose benzimidazole use in some species, potentially leading to decreased blood cell production. Any bird showing signs of severe illness during or shortly after oxfendazole treatment should receive emergency veterinary care. Toxicity risk increases significantly with dosing errors, emphasizing the importance of accurate weight measurement and dose calculation.

Rare and idiosyncratic reactions to oxfendazole have been documented in avian patients. Some individual birds may show hypersensitivity to the medication that is not predictable based on species or previous exposure. Long-term or repeated use of benzimidazoles may carry theoretical risks of cumulative toxicity, though this is poorly documented in avian species. When large numbers of parasites die simultaneously following treatment, some birds may experience a temporary worsening of clinical signs due to the inflammatory response to dying parasites and release of parasite contents. Bird owners should contact their avian veterinarian if their bird shows any unexpected symptoms during treatment, develops worsening clinical signs rather than improvement, or fails to return to normal behavior within a reasonable time after completing treatment. Close monitoring throughout the treatment period allows for early detection and management of any adverse effects.

Known allergy or previous hypersensitivity reaction to oxfendazole or other benzimidazole anthelmintics represents an absolute contraindication to use of this medication. Birds that have experienced adverse reactions to related medications such as fenbendazole, albendazole, or mebendazole may potentially cross-react with oxfendazole due to the similar chemical structures within the benzimidazole class. Previous severe reactions including signs of anaphylaxis, severe gastrointestinal upset, or neurological symptoms following benzimidazole exposure warrant extreme caution or complete avoidance of oxfendazole. Bird owners should inform their avian veterinarian of any known medication sensitivities or previous adverse drug reactions before treatment is prescribed. In cases of suspected benzimidazole sensitivity, alternative antiparasitic medications from different drug classes may be recommended.

Birds with significant liver disease or hepatic impairment may require special consideration before oxfendazole administration. The liver plays an important role in metabolizing benzimidazole medications, and impaired hepatic function can affect drug processing and elimination. Birds with known liver disease may experience prolonged drug exposure or accumulation of metabolites, potentially increasing the risk of adverse effects. Avian veterinarians may recommend liver function testing before prescribing oxfendazole in birds with suspected hepatic compromise. Alternative antiparasitic medications with different metabolic pathways may be preferred for birds with documented liver dysfunction. If oxfendazole use is deemed necessary in a bird with mild liver impairment, dose adjustment and enhanced monitoring may be implemented.

Breeding birds and egg-laying hens require careful evaluation before oxfendazole treatment due to potential reproductive effects. Benzimidazole anthelmintics have demonstrated embryotoxic and teratogenic effects in some animal species, and similar concerns may apply to developing avian embryos. Treatment of actively breeding birds or those producing eggs for hatching should be avoided unless the parasitic infection poses a greater risk than the medication. The decision to treat breeding birds must weigh the benefits of parasite control against potential risks to reproductive success. Birds intended for breeding programs may be dewormed outside of breeding season when possible. Eggs produced during or shortly after oxfendazole treatment are generally not recommended for incubation as a precautionary measure.

Several other medical conditions may influence the decision to use oxfendazole in avian patients. Severely debilitated or critically ill birds may not be appropriate candidates for deworming treatment until their condition stabilizes, as the stress of treatment and potential inflammatory response to dying parasites could worsen their status. Significantly dehydrated birds should receive fluid support before antiparasitic treatment. Very young chicks or nestlings may have increased sensitivity to medications and should be treated with extra caution and potentially adjusted doses. Geriatric birds with multiple health conditions may require careful risk-benefit assessment. Complete disclosure of a bird's medical history and current health status to the avian veterinarian enables informed decision-making about treatment appropriateness and helps prevent complications from contraindicated medication use.

Informing the avian veterinarian of all medications, supplements, and treatments the bird is currently receiving is essential before starting oxfendazole therapy. Drug interactions can significantly affect medication safety and effectiveness, potentially leading to increased toxicity or reduced therapeutic benefit. This disclosure should include prescription medications, over-the-counter products, herbal supplements, vitamins, and any other substances being administered to the bird. Even treatments that seem unrelated to parasite control could potentially interact with oxfendazole. Additionally, information about recent past medications is valuable, as some drugs have prolonged effects or elimination times that could influence interactions.

Oxfendazole may interact with other medications that affect liver metabolism, as the hepatic cytochrome P450 enzyme system plays a role in benzimidazole processing. Medications that inhibit liver enzymes could potentially increase oxfendazole levels and prolong its effects, while enzyme-inducing drugs might accelerate metabolism and reduce efficacy. Concurrent use of other antiparasitic medications should be coordinated carefully, as combinations may either enhance therapeutic effects or increase toxicity risks. Some antifungal medications, particularly certain azole antifungals, may interact with benzimidazoles through shared metabolic pathways. Antibiotics and oxfendazole are sometimes used concurrently in birds with mixed infections, but the combination should be veterinarian-supervised.

Supplements and dietary factors can potentially influence oxfendazole absorption and effectiveness. High-fat foods may enhance absorption of benzimidazole medications, which could be clinically relevant for efficacy but also for potential toxicity. Calcium supplements and mineral blocks may theoretically affect drug absorption, though this interaction is not well documented for oxfendazole specifically. The timing of vitamin supplements, particularly fat-soluble vitamins, may need consideration during treatment. Probiotic supplements are often recommended following antiparasitic treatment to support restoration of healthy gut flora, but timing of probiotic administration relative to medication dosing may optimize both treatments. Bird owners should discuss supplement regimens with their avian veterinarian when oxfendazole treatment is prescribed.

Monitoring during oxfendazole treatment should include observation for any signs of unexpected drug interactions or enhanced effects. Signs of potential interaction may include increased severity of expected side effects, unusual symptoms not typically associated with oxfendazole, or reduced therapeutic response. Avian veterinarians may recommend specific monitoring parameters based on the other medications a bird is receiving. Dose adjustments may be necessary when oxfendazole is combined with certain other treatments. Bird owners should promptly report any concerning changes in their bird's condition during treatment, as this could indicate an interaction requiring veterinary assessment. Maintaining a complete medication diary including all treatments, supplements, and timing of administration facilitates identification of potential interactions and optimal treatment management.

Several general precautions apply to the use of oxfendazole in avian patients to ensure safe and effective treatment. Accurate measurement of the bird's body weight is paramount before each treatment, as dosing errors represent one of the most significant risks associated with antiparasitic therapy. Small birds in particular require precise measurements in grams using a reliable scale, as even small errors can result in significant over- or under-dosing. Following the avian veterinarian's instructions exactly regarding dose amount, timing, and duration is essential for optimal outcomes. Never adjust the prescribed dose or treatment schedule without veterinary guidance, even if the bird appears to improve or experiences mild side effects.

Species-specific variations in oxfendazole sensitivity have been documented and should inform treatment decisions. Certain bird species may be more susceptible to benzimidazole toxicity than others, though comprehensive species-specific safety data is limited for many avian species. Finches and other small passerines may require particular caution due to their small body size and potentially different metabolic characteristics. Ratites such as ostriches and emus have shown varied responses to benzimidazole medications. Avian veterinarians with experience treating the specific species in question are best equipped to advise on appropriate precautions. When treating rare or unusual species with limited documentation, conservative dosing approaches may be warranted.

Environmental precautions and safe medication handling protect both the bird and human caregivers during treatment. Oxfendazole formulations should be handled according to label directions, with appropriate hygiene measures including handwashing after administration. While oxfendazole is not considered highly toxic to humans, minimizing unnecessary exposure is prudent, particularly for pregnant women and children. Medication should not be allowed to contaminate food preparation areas or water supplies. Spilled medication should be cleaned promptly. When disposing of unused medication or contaminated materials, following appropriate disposal guidelines prevents environmental contamination and accidental exposure.

Monitoring during oxfendazole treatment allows early detection of any problems and assessment of treatment efficacy. Bird owners should observe their bird closely for signs of adverse effects including lethargy, appetite changes, abnormal droppings, or neurological symptoms. Positive signs that treatment is working may include improvement in clinical signs that were associated with parasite infection, such as improved appetite, weight gain, and better feather condition. However, improvement may not be immediately apparent and does not replace follow-up fecal testing to confirm parasite elimination. Avian veterinarians may schedule recheck examinations during or after treatment to assess progress and adjust the treatment plan if needed.

Special populations of birds require additional consideration when oxfendazole treatment is contemplated. Geriatric birds may have decreased organ function affecting drug metabolism and may benefit from conservative dosing approaches. Juvenile birds and chicks may show increased sensitivity to medications and require careful dose calculation. Birds with concurrent illnesses or immunocompromised states may need modified treatment approaches. Birds experiencing heavy parasite burdens may be at risk for complications when large numbers of parasites die simultaneously, and supportive care may be indicated. Any bird with known chronic health conditions should be evaluated carefully to determine if antiparasitic treatment is appropriate and whether modifications to standard protocols are needed.

Proper storage of oxfendazole maintains medication potency and ensures treatment effectiveness throughout the course of therapy and beyond. Most oxfendazole formulations should be stored at controlled room temperature, typically between 59 and 86 degrees Fahrenheit (15 to 30 degrees Celsius), unless otherwise specified on the product labeling. The medication should be protected from excessive heat, as elevated temperatures can accelerate degradation of the active ingredient. Direct sunlight should be avoided, and storage in a dark location or opaque container helps prevent light-induced breakdown. Moisture protection is also important, so storage in areas with high humidity such as bathrooms should be avoided. A secure medication cabinet away from temperature fluctuations provides ideal storage conditions.

Different formulations of oxfendazole may have specific storage requirements that should be followed carefully. Oral suspensions typically require shaking before each use to ensure uniform distribution of the medication throughout the liquid. Some liquid formulations may require refrigeration after opening, while others remain stable at room temperature. Expiration dates should be checked regularly, and expired medication should not be used, as efficacy cannot be guaranteed beyond the labeled expiration. Compounded formulations prepared by veterinary pharmacies may have shorter shelf lives than commercial products and should include beyond-use dating information. Once a treatment course is completed, remaining medication should be stored properly for future use only if it will remain within its expiration date.

Safe handling and disposal of oxfendazole protects both household members and the environment. The medication should be kept in its original container with child-resistant closure when not in use, stored out of reach of children and pets. Accidental ingestion by humans or household pets should prompt contact with poison control or medical/veterinary care. When disposing of unused or expired medication, following proper disposal guidelines is important to prevent environmental contamination and potential exposure of wildlife. Many communities offer medication take-back programs that provide safe disposal options. If take-back programs are not available, specific disposal instructions on the product label should be followed, or medication can be mixed with undesirable substances and placed in sealed containers for household trash disposal. Compounded medications should be disposed of according to the compounding pharmacy's guidance, and any concerns about storage or handling should be directed to the prescribing avian veterinarian or dispensing pharmacist.

The effects of oxfendazole can vary significantly across different bird species, making species-specific considerations an important aspect of treatment planning. Metabolic rate, body composition, and individual organ function can all influence how a bird processes and responds to antiparasitic medication. Avian veterinarians draw on species-specific knowledge and clinical experience when prescribing oxfendazole to ensure appropriate dosing and monitoring for each patient. Some species have been studied more extensively than others regarding benzimidazole use, and treatment of less commonly kept species may require additional caution. Understanding the parasites that commonly affect specific bird groups also informs treatment decisions.

Psittacine birds including parrots, macaws, cockatoos, and parakeets represent a diverse group commonly treated with oxfendazole for nematode infections. These birds vary enormously in size from small budgerigars to large macaws, requiring careful attention to weight-based dosing. Psittacines are generally considered to tolerate benzimidazole medications reasonably well at appropriate doses, though individual sensitivity can occur. Common parasites affecting psittacines include Ascaridia species and various Capillaria species. Psittacine birds housed with outdoor access or in aviaries with ground contact have higher parasite exposure risk. Regular fecal monitoring and appropriate deworming are important components of preventive health care for these species.

Other bird groups have their own considerations regarding oxfendazole treatment. Passerine birds such as finches, canaries, and softbills often require compounded formulations due to their small size and the need for precise small-volume dosing. These small birds may be more susceptible to dosing errors and require particular attention to accuracy. Poultry species including chickens, turkeys, and game birds have been treated with benzimidazoles extensively, though withdrawal times may apply if eggs or meat are intended for human consumption. Raptors and birds of prey may be treated with oxfendazole for specific parasitic infections, though these species are often managed by specialized wildlife veterinarians. Ratites, waterfowl, and other bird groups each have unique considerations based on their physiology and husbandry.

Body size considerations significantly influence oxfendazole treatment approaches across the range of avian species. Large birds such as macaws, cockatoos, and poultry may receive doses calculated from commercially available formulation concentrations without difficulty. Medium-sized birds require careful measurement but can often be treated with available products. Small birds present the greatest dosing challenges, as standard formulations may be too concentrated for accurate measurement of tiny doses. Compounding pharmacies can prepare diluted formulations specifically designed for small bird species. Accurate gram-scale weights are essential regardless of bird size, but measurement precision becomes even more critical for smaller patients. Working with an avian veterinarian experienced in treating birds of similar size to the patient helps ensure appropriate treatment protocols are selected.

Several alternative anthelmintic medications within the benzimidazole class share similar mechanisms of action with oxfendazole and may be considered as alternatives in certain situations. Fenbendazole is perhaps the most commonly used benzimidazole in avian medicine and has an extensive track record of use in various bird species. Albendazole is another benzimidazole option, though it may carry somewhat higher toxicity concerns in some species. Mebendazole has been used historically in birds but is less commonly prescribed currently. The choice between different benzimidazoles may depend on factors including local availability, cost, formulation options, and species-specific safety data. If one benzimidazole proves ineffective or causes adverse effects, switching to another member of the class may or may not be appropriate depending on the specific circumstances.

Medications from different drug classes provide options when benzimidazoles are contraindicated or ineffective. Ivermectin, a macrocyclic lactone antiparasitic, offers broad-spectrum activity against many internal and external parasites and represents a commonly used alternative to benzimidazoles in avian medicine. Pyrantel pamoate is effective against certain nematode species and may be used when benzimidazoles are not suitable. Levamisole is another anthelmintic option with a different mechanism of action. For birds with parasites resistant to one drug class, rotating to a different mechanism may improve treatment success. Combination therapy using multiple drug classes simultaneously or in sequence may be recommended for severe or mixed infections. The selection of alternative antiparasitics should be guided by fecal examination results, species considerations, and veterinary expertise.

Supportive and complementary therapies may accompany oxfendazole treatment to optimize patient outcomes and overall health. Probiotic supplementation following antiparasitic treatment helps restore healthy intestinal microflora that may be disrupted during treatment. Nutritional support including vitamin supplementation may benefit birds recovering from parasitic infections, as parasites often cause nutritional deficiencies. Environmental management including thorough cleaning and disinfection of enclosures helps prevent reinfection after successful treatment. Quarantine protocols for new birds entering a collection help prevent introduction of parasites to established populations. It is essential to emphasize that any medication changes or substitutions should only be made under avian veterinary guidance, as inappropriate antiparasitic use can be ineffective, harmful, or contribute to resistance development. Bird owners should never substitute medications without professional advice.