Antibiotic treatment

Since the discovery of penicillin by Alexander Fleming in 1928, antibiotics have saved millions of lives, in both human and veterinary medicine. They are an invaluable tool used against many diseases and are constantly evolving. Antibiotics are incredibly useful and invaluable, but they can pose a significant challenge when used in rabbits.

Antibiotics are important medicines used to treat infections caused by bacteria; they work by slowing their growth or killing the bacteria. There are many types of antibiotics; some of the more common ones include:

• Penicillins, eg penicillin G and amoxicillin.
• Cephalosporins, eg cefaclor, cefadroxil, cefalexin.
• Tetracyclines, eg tetracycline and doxycycline.
• Aminoglycosides, eg gentamicin, however these are contraindicated and dangerous to rabbits.
• Clindamycin.
• Suphonamides and trimethoprim, eg co-trimoxazole.
• Metronidazole and tinidazole.
• Quinolones, eg ciprofloxacin, enrofloxacin, levofloxacin and norfloxacin.

Rabbits are hindgut fermenters and rely upon microbial digestion. This means that rabbits have literally millions of ‘friendly’ bacteria within their digestive system.

Antibiotics are by their very nature designed to ‘kill’ bacteria, and some types of antibiotics are not selective about what bacteria they invade and kill off. This means that certain types (notably aminoglycosides) must never be given to rabbits as they are highly likely to kill off the ‘friendly’ bacteria within their digestive system, leading to potentially and often fatal diarrhea. Other antibiotics, eg penicillins and clindamycin, should be given to rabbits via injection rather than orally to minimize the risk of digestive upsets; nutritional support should be given to rabbits undergoing antibiotic treatment in the form of probiotics for a minimum of 10 days afterwards.

Your veterinarian can guide you on what antibiotics are suitable for your rabbit. It is worth noting that the only antibiotic that has a licence for use in rabbits is enrofloxacin (Baytril). Any other antibiotic that is used must be given ‘off label’. This mean that there is no alternative drug that has a license for that species or for that particular condition and your veterinarian is prescribing the ‘off label’ drug based on evidence of its use in other species for similar conditions. This is common practice in rabbit medicine since so few drugs are licenced for rabbits and often the results of a culture and sensitivity test will indicate a particular antibiotic is needed. Invariably this is unlikely to be licenced for use on rabbits. Your veterinarian should always discuss this with your first.

Adverse reactions can occur to any medication and to any animal. There are always risks involved with any drug, and no one drug can ever be 100% safe in all situations. Adverse reactions can occur, but by selecting appropriate antibiotics that are generally safe to use in rabbits, giving the correct dose for the correct amount of time, and if possible, using injectable antibiotics, the risks are minimized. It is important to watch closely for side-effects and stay in contact with your veterinarian. If you are concerned, then you should speak to your veterinarian immediately.

Adverse reactions are likely to be related to the digestive tract and will include liquid diarrhea, collapse and potentially death in the most serious of reactions. Other reactions may include lethargy, increased heart rate and GI stasis. If you are concerned about your rabbit, you must speak to your veterinarian immediately.

All that said, antibiotics have a very useful and important role in the veterinary treatment of rabbits, and without the option of using them, we would be able to treat many conditions far less successfully.

Antibiotics do not work against viral infections. For example, a rabbit suffering from myxomatosis would not benefit from being treated with antibiotics. However, rabbits with myxomatosis often develop a secondary bacterial infection in their respiratory tract; for this, antibiotics may be prescribed.

Antibiotics are useful in cases of bacterial infection, eg abscesses, respiratory infection, urinary infections, and to prevent infection in wounds.

Antibiotics work according to the type of bacteria; some have a broad spectrum (will be effective against several bacterium), and others have a narrow spectrum, so may only work against one or two types of bacteria.

Ideally, a culture and sensitivity test should be carried out before starting antibiotic treatment. This involves taking a sample of any discharge from the affected area, eg a wound, bodily fluid or from an orifice, although this isn’t always possible. The sample is then sent away to a laboratory so they can ‘grow’ the bacteria and decipher which is the best antibiotic to use.

Antibiotic resistance is fast becoming a serious problem in human medicine, and is likely to follow the same path in veterinary medicine. The same antibiotics are used in human medicine that are used in animals.

Bacteria are living organisms and can adapt and find ways to survive the effects of an antibiotic. They become ‘antibiotic resistant’, meaning that the antibiotic no longer works against that strain of bacteria. This happens the more often we use an antibiotic. Potentially a situation can arise whereby a bacterium is resistant to all known antibiotics.

By using antibiotics less often, we can slow down the development of resistance, and antibiotics should never be used unnecessarily. It is imperative to always use the correctly prescribed antibiotics, at the correct dosage and for the correct length of time.