Which Drugs and Why – Pros and Cons of Medication

In this chapter we will be looking at the three most common classes of drugs that may be prescribed by your veterinarian, their uses and most likely side effects. When used intelligently and safely after a proper diagnosis, drugs can really enhance the quality of your pet’s life. Some of them are life-saving and are compulsory in emergency situations. However, when they are prescribed indiscriminately and unnecessarily, drugs can cause more harm than good.

An impatient owner who wants quick results can force even the most well-meaning, holistically minded veterinarian to prescribe needless medication, while a well-informed pet guardian who has the long-term wellness of her pet in mind will request and choose the more natural options, which are safer and have no known side effects.

The Collins dictionary defines ‘drug’ as ‘any synthetic or natural chemical substance used in the treatment, prevention or diagnosis of disease’. Medicines, agents and compounds are all synonyms for drugs. Any one drug can have many names, unfortunately, which can be very confusing.

All drugs have at least two nonchemical names: a generic name, which has been officially approved, and a brand name, which is the commercial name chosen by a pharmaceutical company. In most cases the generic name will provide a clue to the pharmacotherapeutic action and/or classification, but not in all cases.

To make matters more confusing, these generic names can vary between countries and so can brand names. If you are in any doubt, always contact your vet to check if you have the correct drug. Today a lot of pet owners buy drugs from online pharmacies, so it is vital they have some knowledge of drugs, their names, benefits and side effects.

ANTIBIOTICS/ANTIBACTERIALS

Antibacterials are undoubtedly the most important therapeutic discovery made in the 20th century. Today, these medications are probably the most frequently used and abused in conventional veterinary practice. Antibiotics are by-products of other microorganisms, like moulds, and are used to treat infections caused by bacteria.

Antibiotics are known to have selective toxicity, as they interfere with a vital function of the bacterial cell such as cell wall synthesis, DNA replication, protein synthesis, folic acid metabolism, etc., but have minimal or no effect on the host (animal or human) cells. It is because of their selective toxicity that antibiotics have what is called a high therapeutic index (the ratio of the toxic dose to the therapeutic dose) or, in simple terms, excellent safety profiles.

It is important to know that an antibiotic’s ability to inhibit or kill bacteria will depend on its concentration, and that its bactericidal (killing) property can be both concentration-dependent or time-dependent, which is why your vet will insist on using an antibiotic at the same time each day and with the correct time intervals (for example: use twice daily, 12 hours apart).

Sometimes your vet may prescribe more than one antibiotic. This is because certain antibiotics may act together synergistically. In the same way, some may act antagonistically, or oppose each other, so it is best not to medicate your pet with antibiotics yourself.

Some of the most commonly used antibiotics in small animal veterinary practice, along with their popular brand names, are listed in the following table.

Vets consider several factors before deciding on a particular antibiotic for your pet. Sometimes though, many pets are treated with them for prolonged periods of time – intermittently or continuously – without even a proper diagnosis to justify their use. In my experience, this usually happens when the pet owner cannot afford the tests required to arrive at a diagnosis and would rather just spend on treatment.

Side effects

Gastrointestinal symptoms, like vomiting and diarrhoea, are probably the most common side effects of antibiotics. Very rarely, just like humans, pets can also suffer a severe allergic reaction to an antibiotic, usually after taking one or two doses. When antibiotics are taken for prolonged periods your pet may also become more susceptible to yeast infections.

Vets and pet owners should both insist on culture and sensitivity testing to ensure the appropriate antibiotic is being prescribed. It is also very important that the correct antibiotics are used at the right dose, at the right time each day and for the right length of time. Pet owners have a tendency to stop using the antibiotic as soon as the pet appears to be back to normal. The course must be completed even if the pet appears to be well, as otherwise relapse is very common.

Resistance

Antibiotic resistance is a real problem today. It happens when bacteria are no longer killed by the antibiotics that have previously been effective. There is increasing fear that this resistance will spread to such an extent that we might return to the ‘dark ages’, when there was no treatment for many of the infections that afflict both humans and animals.

The improper and overzealous use of antibiotics by vets, and poor compliance by owners, are considered as contributing factors. The UK’s Veterinary Medicines Directorate (VMD) has called for responsible antibiotic use by vets, farmers, animal keepers and pet owners. The focus should be on improving pet health through good nutrition, and as far as possible avoiding antibiotic use.

Complementary therapies

There are several herbs, spices and foodstuffs with antibacterial properties. Aloe vera, garlic, tea tree and turmeric can be tried (see Chapter 3, A–Z Pet-Friendly Herbs). I also prefer to use antibacterial shampoos rather than systemic antibiotics for recurrent skin infections.

NON-STEROIDAL ANTI-INFLAMMATORY DRUGS (NSAIDS)

NSAIDs are the second-most commonly prescribed medications and are used extensively in small animal practice, especially in dogs. These drugs are sometimes referred to as aspirin-like drugs, as their actions are very similar to those of aspirin, which was introduced into human clinical medicine way back in the 1890s. The three main therapeutic effects of NSAIDs are:

• An anti-inflammatory effect: they modify the inflammatory reaction present.
• An analgesic effect: they reduce certain types of pain, especially pain caused by inflammation.
• An antipyretic effect: they can lower the body temperature if it is increased during disease or fever.

Vets tend to prescribe NSAIDs for symptomatic relief from pain and swelling, which is present in chronic joint disease like osteoarthritis, and also to alleviate pain caused by acute inflammatory conditions such as dog or cat bite injuries, fractures, sprains and other soft tissue injuries. They are also used to provide relief from post-surgical pain, dental procedures and any minor aches or pains.

While most NSAIDs bring about their drug action in a similar way, there are striking differences in their toxicity and the degree of tolerance between dogs and cats – and even within dogs and cats. It is very unwise, therefore, to try and use them without veterinary advice. For example, Paracetamol must not be used in cats, as they lack the special enzyme called glucoronyl transferase that is required to metabolize this drug and can therefore die if given it.

The table below gives the most common NSAIDs used by vets in small animal practice, and their popular brand names.

Most NSAIDs are metabolized in the liver and excreted by the kidney. To a large extent they all share the same types of mechanism-based side effects. All these effects are thought to be due to their primary action – inhibition of the fatty acid COX enzyme, and thus inhibition of the production of prostaglandins and thromboxanes.

Their anti-inflammatory action is thought to be due to their inhibition of COX-2, and their unwanted side effects, particularly the gastrointestinal disturbances like gastric irritation, are said to be largely a result of their action on COX-1.

Side effects

Gastrointestinal ulceration and irritation are common side effects of almost all NSAIDs, but some of them can cause gastrointestinal bleeding, neurological and behavioural problems and even anaemia. Most vets will advise that if there are signs of adverse reaction, like severe vomiting and diarrhoea or bloody stools, these drugs must be stopped immediately.

When possible vets will avoid prescribing NSAIDs to pets that are elderly, have a previous history of gastrointestinal ulcer or bleeding or have kidney, liver or heart problems. A very important precaution or contraindication with NSAIDs is that they must not be administered concurrently or within 24 hours of giving another NSAID or a steroid. It is important to mention that prolonged use of any NSAID is not in the best interests of your pets, especially if they are on it for several years in conditions such as arthritis.

Complementary therapies

It is a good idea for pet owners to try complementary therapies for chronic pain and inflammation, such as herbs (see Chapter 3, A–Z Pet-Friendly Herbs) and joint supplements such as Synoquin EFA – containing glucosamine and chondroitin sulphate with Dexahan krill oil, antioxidants and omega-3 fatty acids. A good, balanced diet is very beneficial and acupuncture and acupressure can also be very useful to help with chronic pain (see Chapter 6, Fingers and Thumbs).

CORTICOSTEROIDS

The correct name for these drugs is Glucocorticoids but they are more commonly referred to as ‘steroids’. They have been abused frequently, both by vets and doctors, in the past. However, recently there has been more awareness and as a result, their use is now much more prudent.

Steroids are not as ‘horrible’ or ‘evil’ as most people think. They are wonderful, life-saving drugs that have huge benefits when used properly. Corticosteroids are very good as anti-inflammatory and pain-relieving medications. However, it is their ability to relieve itching that has led to their long-term use in the allergic skin conditions that afflict pets.

In emergency situations, where the pet is in severe shock or has neurological signs because of injuries to the brain or spinal cord, steroids were thought to be beneficial. On the contrary, recent research seems to suggest that their use could in fact be detrimental and should be avoided. Their use in emergencies is therefore still a very grey area among vets and is a subject of controversy.

In autoimmune diseases like lupus, pemphigus, immune-mediated anemias, etc., where the pet’s immune system is fighting itself, steroids have proven to be very effective because of their immunosuppressive properties. Steroids are also used in the treatment of Addison’s disease, chronic atopy, inflammatory bowel disease and some cancers.

The table below lists the commonly used steroids used in small animal veterinary practice, along with their brand names. They may be in the form of tablets or gels or creams or powders, and so on, but they contain the steroid mentioned as the active ingredient.

On the flip side, the very same properties that make steroids useful can make them harmful, which is why they should be used with care and consideration. They can impair wound healing and bring about delayed recovery from infections, so they should be used with caution in these situations.

Pets that are on long-term steroids must therefore be carefully monitored for infections. Steroids are no longer being used orally in the treatment of arthritis but are still being used as intra-articular or joint injections in worst-case scenarios. Their immunosuppressive nature, while useful in immune-mediated disease, is detrimental to the immune system as it renders the body more susceptible to infections.

Side effects

Both short- and long-term side effects are observed as a result of steroid use. A transient increase in appetite, water intake and urination is seen mainly in dogs that have been given steroids. Cats seem to have better tolerance to the drugs, and exhibit relatively fewer side effects, but equal care should be taken to prevent unnecessary steroid use.

The short-term side effects are not really harmful when compared to the long-term ones. Prolonged steroid use can suppress the HPA (hypothalamic-pituitary axis) and cause adrenal atrophy. Iatrogenic Cushing’s disease may also develop with prolonged steroid use. Other effects, such as vomiting, diarrhoea and gastrointestinal ulceration, may also occur. Excessive use of steroid skin cream and gels has been known to cause epidermal atrophy or thinning of the skin with wrinkling.

Osteoporosis (thin bones), high blood pressure, water retention, hair loss, infertility, birth defects, fatty liver, obesity, cataracts, thromboembolism (blood clots in lungs) and raised liver enzymes are the less likely side effects of steroids. It should be noted that not all pets and not all steroids will exhibit all these possible side effects.

Steroids should not be prescribed for conditions affecting pregnant animals, pets with diabetes mellitus and those with renal/kidney disease. Pets that have ulcerative keratitis/corneal ulcers should not be prescribed eye preparations that contain steroids. All vets are aware of these contraindications and will try their best to adhere to them.

Most veterinarians will therefore prescribe steroids in supraphysiologic doses – to maximize the therapeutic benefit but minimize the dose-related side effects. Systemic steroids (oral/injections) are therefore started off in high doses and then gradually tapered to give the minimal effective dose. Giving steroids every two days is enough in most cases – especially in chronic skin conditions to control the itching – rather than giving them every day.

The key point here is that steroids may be the best therapy for some pets, for certain conditions, in order to ensure a decent quality of life. The aim of this chapter is not to frighten you or put you off steroids completely, but to help you make an informed choice.

There is no doubt that long-term steroid use may reduce the life span of your pet for the reasons mentioned above. However, a well-informed risk-to-benefit assessment must be made before deciding against them. This is where complementary therapies can be beneficial.

Complementary therapies

Usually, any skin condition that responds to steroids will also respond to a proper natural diet or a hypoallergenic diet. Supplementing with raw foods, antioxidants, omega-3 fatty acids, oil of evening primrose, cleansing hypoallergenic shampoos and herbal remedies (see Chapter 3) will go a long way in alleviating chronic dermatitis or itchy skin problems. Acupuncture, glucosamine and chondroitin sulphate, krill oil and herbal remedies, hydrotherapy and massage can alleviate chronic arthritic pain.

Inflammatory bowel disease responds very well to dietary management (see Chapter 1, Food Is Medicine) and probiotics. Herbs, good diets and immune-strengthening food supplements may benefit animals with immune-mediated disease by at least helping them to do well on lower steroid doses. Immunotherapy vaccines tailor-made after allergy testing are a good alternative to steroid use in chronic allergic skin disease but can be expensive.

The bottom line is this – ‘use drugs with caution’. An open discussion with a holistically minded veterinarian will help you make the right choice for your pet.