The Complete Guide to Amoxicillin for Cats


As history goes, one day in September 1928, Alexander Fleming returned to his laboratory. He found a petri dish containing Staphylococcus bacteria, did not have its lid in its place. It had, therefore, become contaminated with blue-green mold, Penicillin notatum. Apart from the mold, Fleming also noticed a clear ring encompassing the mold. However, the bacteria did not grow in that ring. The discovery fueled Fleming to create penicillin, the first antibiotic that has revolutionized the world of medicine. Although it took a while to be considered safe for general use, penicillin is used to treat humans and animals. Amoxicillin belongs to the penicillin family, and regarding its use in our feline friends, here is a complete guide to amoxillin for cats.

What Does It Treat?

According to All About Cats, amoxicillin is a bactericidal antibiotic. It kills some strains of bacteria-causing infections. Most of the infections amoxicillin treats are of the bladder, urinary tract, and respiratory tract. It is not just used to treat cats; even dogs, reptiles, birds, and ferrets also benefit from this drug. It works by attacking the wall surrounding the bacteria. As a result, the bacterial cells are injured, preventing them from harming the body further. The fact that this antibiotic kills the bacteria directly is what makes it bactericidal. However, it is important to note that regardless of how effective amoxicillin is in fighting bacterial infections, it is ineffective in killing viruses. Thus, it should not be used to treat viral infections. SingleCare published that before deciding if an antibiotic is necessary, you must determine if the infection is due to a viral or bacterial infection. It explains that conditions such as upper respiratory infections could have bacterial or viral components, and sometimes both. Administering amoxicillin when your cat has a viral infection is not only unnecessary, but it could lead to antibiotic resistance among some bacteria types. A visit to the veterinarian will help you determine the type of infection your cat has and the exact species of bacteria causing the infection. This step is crucial because antibiotics do not treat conditions but rather the type of bacteria. Therefore, only after a vet is sure that the type of bacteria causing the infection is treatable with amoxicillin, will s/he administer a dose.

Can Cats Develop Resistance to Amoxicillin?

Through culturing the infected area, a vet also assesses if the bacteria will respond to the treatment. Culturing also helps to check if it is already resistant to the medication. If culturing also shows that the bacteria have low sensitivity to the medication, treating the cat with the drug increases its risk of developing resistance. However, contrary to popular belief, it is not a person or pet that resists the drug; instead, it is the bacteria itself. According to Medical News Today, since bacteria have been around for ages, they have become highly adaptable to different environments. Besides, they regenerate fast and make quick genetic changes across a population. One of the ways that bacteria become resistant to the drug is by changing the format of the drug’s binding proteins in their wall so that the amoxicillin cannot bind to it. Other bacteria dispose of the medication by repurposing the efflux pumps meant to release substances from the cell. Alternatively, the bacteria produce a penicillin-degrading enzyme, penicillinase. One of the most difficult to treat is Pseudomonas ear infection. However, even E. coli, Salmonella, and Enterococcus bacteria species responsible for most gastrointestinal and urinary tract infections are problematic.

The most common cause of antibiotic resistance in pets is administering the drugs even when it is unnecessary. For instance, an animal going into surgery and has a high risk of developing an infection can be given an antibiotic. Otherwise, it is not necessary. Since bacteria are highly adaptable, exposing them to antibiotics frequently leads to them developing survival mechanisms; hence, the resistance. Also, giving animals antibiotics for less than the required dosage period is likely to result in antibiotic resistance. You can tell when your cat has developed an antibiotic-resistant bacterial infection if it does not respond appropriately to the medication. Additionally, a fever whose origin is unknown could be a sign. However, the only way you can tell for sure that your furry friend will not respond to amoxicillin is through the culture and sensitivity test.

What Is The Right Dosage?

Even if your cat has a bacterial infection resistant to antibiotics, it can be treated using stronger antibiotics. Unfortunately, this is highly inadvisable because such drugs damage the liver and kidneys. Sometimes, treating the underlying condition and providing supportive care prevent the use of riskier antibiotics. An alternative when dealing with skin infections, perhaps after surgery, is to use aggressive topical antiseptics. They are applied during bath time or as sprays or creams. Usually, applying them twice or thrice a day will clear the infection. Instead of worrying about damaging your cat’s health using the more aggressive drugs, the ideal way to prevent resistance is by administering the correct dosage. Most pet owners stop administering the drug before the dose is over because animals are not excited about taking it. As vets warn, even if your animal’s health improves after a few days, you should not stop administering until they have finished the dose. No matter how well your cat seems to have recovered, stopping the medication earlier puts it at risk of developing an infection again. As Illinois News Bureau published, most antibiotics have to be administered for at least 21 days. Pet owners give their animals the drug for a week or two; as a result, the bacteria develop resistance.

Even if the labeled dosage for amoxicillin for cats is once a day, most vets have discovered that it is ineffective for treating most infections. Therefore, they opt to administer the drug after every 8-12 hours. However, this is at the discretion of the vet who has examined the cat. If you forget to administer at the right time, you should only give the cat that dose if it is close to the scheduled time. If not, skip the dose and administer at the next scheduled time. You should never give two doses at once or compensate by giving extra doses at unscheduled times because you are likely to cause a cat overdose. Overdosing might result in severe side effects such as lack of coordination, palpitations, skin allergies, diarrhea, and vomiting. The vets recommend between five to ten mg for every pound of the cat’s weight. Since the drug comes in tablet form or a suspension, you can decide the best way, depending on how fussy your cat is. The tablets are trademarked Amoxi-tabs and are available in 50, 100, 150, 200, and 400 mg tablets. The liquid amoxicillin is trademarked Amoxi-Drops and comes in a 50ml/mg suspension. Once your cat becomes resistant to regular amoxicillin, vets will prescribe Clavamox. It is a mixture of amoxicillin and clavulanate potassium. Liquid amoxicillin has to be reconstituted and refrigerated. Usually, the vet will reconstitute it for you, and you should discard it after 14 days. If the vet prescribes two bottles of the drug, s/he will provide instructions for reconstituting the second bottle. The taste may not be likable to most cats; hence, they spit it out. For this reason, the easiest method is arguably hiding the pill in the cat’s food. If your cat refuses to take the drug but eats the food, mixing it with food is the best guarantee.

Does Amoxicillin Have Any Side Effects?

Some cats could have severe allergic reactions to the drug. Although rare, you might notice your cat experiencing labored breathing, excessive scratching, swelling of the mouth and nose, and skin redness. Other allergic reactions include diarrhea and vomiting. Cats with respiratory problems might have decreased appetite because they cannot smell their food. Hence, smelly foods like tuna might do the trick. The moment you notice such reactions upon amoxicillin administration, you should contact your vet immediately. Cats that are allergic should not be treated using the medication. Besides allergic reactions, the drug could cause side effects such as kidney or liver damage and fever. Usually, when the cat reacts by vomiting or diarrhea, it could be because the antibiotic is taking its toll on the digestive system. Therefore, you must always confirm if your pet should take the drug with or without food because usually, feeding it can offset the side effects. Another reason for side effects could be that your cat already has another antibiotic in its system. It is not recommended to mix amoxicillin with another antibiotic, other drugs, or additive because its effectiveness will be affected. Some combinations will hinder the antibiotic from working optimally in killing the bacteria, thus causing antibiotic resistance. Some drugs that react with amoxicillin include antacids, bacteriostatic, neomycin sulfate, chloramphenicol, tetracycline, and aminoglycosides. It is, therefore, advisable to inform your vet of any drugs your pet may be taking. You should not be tempted to stop the medication to avoid the side effects because that will give the bacteria room for growth. Instead, the vet might prescribe a probiotic to administer alongside the amoxicillin.

Is Human Amoxicillin Safe for Cats?

Some human antibiotics pose great danger for our furry friends. You should avoid topical antibiotics because cats can lick them, and the ingestion causes serious illnesses that can be fatal. Even fluoroquinolones, a class of antibiotics, are not safe because they cause seizures in cats. Human antibiotics, such as amoxicillin, tetracycline, and ampicillin are considered safe for administering to cats. The reason why such drugs will not harm cats is that vets sell medication equivalent to human drugs. Therefore, even prescriptions are usually similar.

While giving cats and other animals human antibiotics will not cause any harm to them, animal antibiotics should not be for human consumption. Although it is common for farmers and other people working with animals to consume medication meant for animals, it is wrong. In fact, it is illegal to sell or dispense medications intended for animals for human consumption. Therefore, you should not be tempted to take your cat’s amoxicillin; animal drugs may not undergo the rigorous scrutiny as human drugs. So even if it does not affect your feline, it might affect you. Besides using human amoxicillin to treat your cats, you might think it is right to self-prescribe because you feel you have already diagnosed the problem.

If your cat suffers from an infection similar to the one it had before when you were given amoxicillin, you should not start treating the cat based on your diagnosis. Even if human amoxicillin is safe for cats, it does not automatically qualify for treating all infections. You might be trying to treat a viral infection which, of course, will not go away using a bactericidal antibiotic. Alternatively, you might end up poisoning your cat. According to Vetinfo, as much as human amoxicillin is considered safe for felines, it contains active ingredients in high amounts; a cat should only get a maximum of a quarter of these ingredients because the dosage is administered depending on body weight. All the same, if you feel that your cat has been taking so many amoxicillin drugs and there is hardly any improvement even after finishing the dose, you can never go wrong with getting a second opinion. Prolonged use of antibiotics will lead to antibiotic resistance, which you should avoid at also costs. Treating it is costly, especially when the side effects are severe. Besides, the lack of improvement could mean something is wrong, and amoxicillin is not the ideal treatment for the issue.

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