Understanding and Correcting Common Clinical Medication Errors in Canine Diseases

Because veterinarians may have an incomplete understanding of the animal being treated, the condition, and how drugs work, various errors can occur during drug use. Although such errors can lead to treatment failure or even toxic reactions, they can also provide a basis for correction when establishing a correct diagnosis and implementing a drug treatment plan for future diseases. Therefore, recognizing and correcting clinical medication errors is a positive practical activity in veterinary clinical practice.

1 Common types of medication errors

The types of clinical medication errors include diagnostic errors, drug selection errors, compatibility errors, dosage errors, and administration and dispensing errors. Their consequences include reduced drug efficacy, adverse reactions, poisoning or death, drug-induced diseases, and increased treatment costs. For example: 1) When sulfonamides are given to a dog with a history of procaine use, the antibacterial action of the sulfonamide is antagonized; 2) When penicillin potassium or sodium salt is injected to treat bacterial diarrhea in animals, the antibacterial spectrum of the drug is incorrect and the efficacy is poor; 3) When bithionol (Bitin) or a preparation containing bithionol is used to deworm adult dogs or puppies, a single dose that is too large can cause symptoms such as diarrhea in mild cases, and enteritis, dehydration, and heart failure in severe cases; 4) When magnesium sulfate is injected intravenously into dogs, death from respiratory center paralysis can occur because the rate is too fast (not because the dose is too large); 5) When cardiotonic agents such as caffeine sodium benzoate or digitalis glycosides are mistakenly injected at the same time as calcium agents (including separate or sequential use), cardiac arrest can occur because calcium ions can weaken myocardial excitability; 6) When chlorpromazine is used together with metamizole sodium, body temperature drops sharply, and an excessive dose can cause animal collapse; 7) Long-term use of aminopyrine, metamizole sodium, or chloramphenicol can cause granulocytopenia; 8) When trichlorfon is used together with sodium bicarbonate or alkaline drugs containing sodium bicarbonate (such as artificial salt), trichlorfon is converted into the highly toxic dichlorvos and causes poisoning; 9) When tetracycline and prednisone are used at the same time, it can cause digestive disturbances in dogs or "superinfection" diseases of gastrointestinal bacteria.

2 Errors caused by improper drug selection

This is especially likely to occur when using antibacterial drugs. Currently commonly used clinical antibacterial drugs include antibiotics, polyether feed antibiotics, sulfonamides and their synergists, furazolidone, olaquindox, and quinolones (norfloxacin, enrofloxacin, ciprofloxacin, etc.). Their errors often manifest as:

2.1 Errors in selecting antibacterial drugs

2.1.1 Abuse of penicillin potassium or sodium salt. Penicillin is inexpensive and effective against infection, and apart from occasional allergic reactions it generally has no toxic side effects, so it is often abused. In fact, it is mainly suitable for diseases caused by Gram-positive bacterial infections, such as pneumonia, endometritis, mastitis, and wound infections, and for a few Gram-negative bacteria.

2.1.2 Using new and expensive antibiotics as routine drugs. For example, cephalosporins (cephalosporin antibiotics), although they can be used for severe infections in which other antibacterial drugs are ineffective, for cases that have already developed drug resistance, or for the treatment of valuable pets, the Ministry of Agriculture has recently explicitly prohibited the transfer of such drugs from human medicine to the veterinary field.

2.1.3 Being misled by advertising and having insufficient understanding of the adverse reactions of certain newly used domestic drugs. For example, among quinolones, norfloxacin, enrofloxacin, ciprofloxacin, etc. have the advantages of a broad antibacterial spectrum, low antibacterial concentration, and no cross-resistance within this class of drugs. However, this class of drugs has been used abroad for 30 years, and not only has resistance emerged, but there are also adverse reactions in the digestive tract and nervous system (vomiting, abdominal pain, neurological symptoms in cats and dogs). They can damage cartilage development in young animals and cause lameness, and in carnivores they easily form crystals in acidic urine and damage the kidneys. These reactions worsen as the dose increases.

2.1.4 Neglecting the normal use of certain inexpensive but effective drugs. For example, furazolidone and certain compound sulfonamide preparations, such as SD + TMP, namely compound sulfadiazine sodium, and SMZ + TMP synergist, namely compound sulfamethoxazole, etc.

2.2 Recommendations for selecting antibacterial and antiparasitic agents

2.2.1 Antibacterial agents can be divided into Class III: Class I commonly used antibacterial drugs, which may include penicillin potassium or sodium salt (mainly effective against Gram-positive bacteria), ampicillin (effective against Gram-positive and Gram-negative bacteria), and gentamicin (used for Gram-positive and Gram-negative bacteria when penicillin is ineffective); Class II specially needed antibacterial drugs, such as chloramphenicol (for intestinal Gram-negative bacterial infections), veterinary kanamycin, erythromycin thiocyanate, and enrofloxacin (for bacterial infections with low efficacy from commonly used antibiotics), etc.; Class III preventive antibacterial drugs, such as olaquindox and oxytetracycline (both used as antibacterial growth promoters), tylosin (an antibacterial, anti-mycoplasma, and anti-Leptospira growth promoter), and diclazuril (a new, highly effective, low-dose, resistance-free anticoccidial agent).

2.2.2 Strictly follow the order of medication. Generally, use Class I first (either one kind or two kinds in combination), then use Class II if the efficacy is poor (or in special cases), and use Class III when used as a feed additive.

2.2.3 Adhere to a reasonable course of treatment. If symptoms do not improve significantly after any antibacterial drug is used 2 to 3 times, it should be replaced promptly with another drug; if it is effective, the maintenance dose should be maintained for one course of treatment (generally 2 to 3 days).

3 Errors caused by dosage factors

3.1 Increasingly larger doses of antibacterial drugs

Whether because of harm from counterfeit or inferior drugs or because of being misled by certain rumors, the clinical dosage of some antibiotics (such as penicillin, ampicillin, and gentamicin) has become increasingly large, resulting in long-term overdose use.

3.2 No dose reduction when antibacterial drugs are used in combination

For example, when penicillin is combined with streptomycin, both drugs can be appropriately reduced (by at least 1/3).

3.3 Insufficient dosage and course of treatment

For example, sulfonamides are required to be dosed according to body weight, with a doubled dose for the first dose, and the maintenance dose should be maintained throughout the course of treatment (2 to 3 days). However, in clinical practice, insufficient dosage (especially insufficient first dose) and failure to maintain the maintenance dose or an insufficient course of treatment often occur.

3.4 Drug measurement errors

The dosage of solid drugs is usually calculated in grams (g), milligrams (mg), and micrograms (μg). For example, for furazolidone, the oral daily dose for dogs is 5 to 10 milligrams per kilogram of body weight, which can be given in 2 divided doses. Each furazolidone tablet contains 0.1 grams of the drug (that is, 100 milligrams). Taking a 5-kilogram puppy as an example, the daily dose is 25 milligrams = 1/4 tablet, given in two divided doses per day, with each dose being 12.5 milligrams. If there is a measurement error, poisoning can easily occur.

3.5 How to use drug doses correctly

Drug dosages differ between legal doses and clinical experience doses. Legal doses are based on records such as the Chinese Veterinary Pharmacopoeia and the Veterinary Drug Specifications. The doses customarily used by clinical veterinarians are empirical doses. The latter should generally be flexibly controlled on the basis of the former. Although clinical discretion may be exercised, safety and effectiveness must be the "limit." Some drugs have strict dosage requirements and must be used according to the legal dose, for example certain antibiotics with toxic side effects (such as streptomycin, chloramphenicol, and doxycycline), sulfonamides, anesthetics (such as chloral hydrate and barbiturates), drugs acting on receptors (such as pilocarpine, atropine, and epinephrine), antiparasitic drugs (such as trichlorfon, albendazole, levamisole, nitroxinil, diminazene, and diclazuril), hormones (such as chorionic gonadotropin, oxytocin, prednisone, and dexamethasone), vaccines and sera, etc. Anesthetics, antiparasitic drugs, antidotes, etc. must be strictly dosed according to body weight. Olaquindox, diclazuril (an anticoccidial agent), etc. must be added to feed with strictly specified concentration measurements.

4 Errors in combined medication

Because there are many kinds of veterinary drugs, combined medication is relatively complex. Only antibacterial agents will be used as an example for explanation.

4.1 Combining antagonistic agents or agents that reduce the efficacy of antibacterial drugs

1) Drugs containing PABA (para-aminobenzoic acid), such as procaine, can antagonize the bacteriostatic action of sulfonamides; 2) Bacteriostatic antibiotics such as erythromycin and chloramphenicol can counteract the antibacterial power of penicillin; 3) When penicillin is used together with sulfonamides, the clinical efficacy of both decreases. Sulfonamide injection is strongly alkaline, and when mixed and injected with penicillin it can destroy the antibacterial activity of penicillin; 4) When sodium bicarbonate is orally administered together with oxytetracycline and tetracycline, it can reduce gastrointestinal absorption of the latter two by 50% and lower drug efficacy; 5) Injectable solutions of vitamin B1, vitamin B2, and vitamin C have varying degrees of inactivation effects on ampicillin, cephalosporins I and II, oxytetracycline, chloramphenicol, doxycycline, streptomycin, kanamycin, lincomycin, etc., that is, the antibiotics lose their antibacterial power, so they must not be mixed for injection.

4.2 Combining antibacterial agents with increased toxicity

1) Dihydrostreptomycin itself has a strong otoneurotoxic effect, and when combined with kanamycin it further aggravates toxicity to the auditory nerve in the ear, etc.; 2) When streptomycin and kanamycin are combined with muscle relaxants (such as succinylcholine), they can aggravate neuromuscular paralysis and the toxic effect of respiratory inhibition.

5 Errors caused by unknown special toxic reactions of drugs in animals

1) Dogs and felids (including tigers, lions, and leopards) have special toxic reactions to phenolic or phenol-containing agents (such as phenol, cresol, compound phenol, and paracetamol). There have been reports of phenol agents causing poisoning and death in cats and tigers; 2) In some dogs, the effective deworming dose of trichlorfon can cause poisoning, so it must be used with caution.

6 Errors caused by improper drug dispensing and usage

Take canine feed premixes as an example: drugs such as furazolidone and olaquindox have certain toxic side effects; sodium selenite and diclazuril are used in extremely small amounts, with added amounts per kilogram of feed of only 0.31 milligrams and 0.1 milligrams respectively. When these drugs are mixed into feed, if a qualified premix is not first prepared, or if the "equal-volume stepwise dilution method" is not used when adding them to feed, uneven mixing will lead to poisoning in dogs. In addition, when the above drugs are made into drinking-water formulations, improper dispensing or failure to add solubilizers or suspending agents often easily causes precipitation, resulting in uneven drug intake by animals and thus poisoning.