Parasite Control

Protecting your pet from parasites is a really important part of pet ownership, particularly now that we and our pets travel so frequently. There is always a risk that vectors such as ticks, flies and mosquitoes will make their way back to our country on us or in our suitcases! However, many transmissible diseases exist naturally within our own countryside.

These diseases may be spread by wild populations of animals, such as Trichomonas in birds, or Encephalitozoon cuniculi in rabbits. They may be spread by ticks, such as Lyme disease (Borrelia burgdorferi), which can affect any animal that a tick can get to – including us!

Pathogens may be spread by mosquitoes, such as canine heart worm (found in the United States), or by biting flies, such as leishmania from sand flies (found throughout Europe).

Let us not forget the humble slug or snail and the transmission of lungworm through the slime trail, when ingested by your dogs and cats.

Finally, many worm eggs are released in the stools of an infected animal, only to be eaten by the next unsuspecting animal that passes.

All pathogens will have a particular favoured ‘final host’, i.e. one they can survive readily inside. For the most part, parasites cannot survive inside an animal that is not a natural host to them, but there are a few exceptions.  in these cases, infections by a parasite in an unnatural host can cause significant disease.

Why do we worry about using parasite treatments?

Many of these pathogens should be sustainable within the environment and their natural hosts at a level that is low enough that no significant population damage is encountered. However, because of the number of pets we keep and the cross-over of territories and walks, we end up with a heavy parasite burden in the environment. This means that it is far more likely that our pets will have access to pathogens, than their wild counterparts may do.

To protect our pets from these risks, we recommend routine parasite treatment. We can never prevent pets from picking up parasites – only treat them when there is a problem, even though this may not be apparent. For example, no flea or tick treatment will prevent your dog, cat, ferret or rabbit from falling prey to fleas or ticks. The treatments work by priming your pet, so that if and when these parasites bite, they will die before they have had an opportunity to transmit any diseases they may be carrying.

Common parasites we recommend protection against

Fleas – final hosts include dogs, cats and rabbits, but fleas will take a meal anywhere if there is no final host around!  Fleas naturally live in garden soil, so are readily picked up by any pets that are laying, rolling, or digging around in the garden. They also commonly carry tapeworms, which are transmitted to your pet when the fleas feed.

Fleas are not vectors that remain on your pet: in fact, only 5% of a flea population is ever on your pet – the remaining 95% is usually in your or your pet’s house (preferable to their natural home of garden soil).  Fleas jump onto their prey, take a bite of some blood, then jump off again until they need another meal – around 2 hours later. That’s 1 bite for your pet every 2 hours, per flea. Not to mention the irritation from having something crawl across their skin at regular intervals! For rabbits, they also carry the risk of transmitting myxomatosis, which is usually fatal.

Whilst in your house, mature fleas will start to lay clutches of eggs. They favour warm, dark places, such as under carpets, under skirting boards, under the television or Hi-fi system, or in warm blankets and bedding. These eggs will hatch in their dozens every couple of weeks, so flea populations grow rapidly, and every mouth must be fed!

To prevent your house from becoming a hot bed of fleas, and to prevent intense irritation for your pets (and sometimes allergic reactions and/or severe anaemia), we recommend regular treatment. This should both kill adult fleas in a timely fashion, and sterilize their eggs so that any they lay before dying will not hatch. Only veterinary prescription medications are capable of both of these functions.

Unfortunately, there is no product available that can kill fleas before they bite, so your pet will have to continue to be bitten in order to kill the adult fleas. If you have a flea infestation, concurrent treatment of the house is recommended to prevent sterile eggs from hatching.  (Ensure your pet is not in the area at the time of spraying, or for an hour afterwards.)

On average, it takes 12 weeks to break the flea cycle, so keep persevering! Vacuum thoroughly on at least a weekly basis, hot wash any soft furnishings and bedding that can be hot washed, and spray the house with a suitable product on a regular basis. Thoroughly clean out your rabbit’s hutch on a weekly basis, and clean out all bedding on a daily basis. Ensure your pet’s parasite treatment does not lapse!

Ticks – the most common final hosts in this country are deer, but ticks will attach to anything that promises a blood meal.  As such, southern areas of the UK (warm areas with lots of deer and sheep) are rife with ticks, and disease prevalence within those ticks is higher than in other areas of the UK.

Ticks go through several moults between being an egg and being an adult, so some can be tiny and others enormous. Once an adult, it is only the females that will feed, in order to feed the hundreds of eggs incubating in their abdomens.

Ticks have a very clever method of attaching to their victims. They hang on a piece of grass or a bush, holding on with 6 of their 8 legs. With the other 2, they wave their arms until something brushes them, then quickly hang on!  They will then crawl up their host until they find somewhere with a blood supply (they sense blood flow beneath the skin), then dig themselves in. They quite literally bury their head. In order to remain this way, they release local anaesthetic in their saliva whilst attaching and whilst in situ. They also glue their head in place with a type of cement, making it very difficult to dislodge them.

As they feed, ticks release a little of their last victim’s blood into the new victim – quite as an accident. This means that any diseases in the previous victim are transmitted to the new one, which is perfect for diseases such as Lyme disease or Babesia canis. On average, it takes around 48 hours for a tick to effectively transmit disease. It is therefore very important that your pet has an effective treatment already within their body before they are bitten. This treatment will not stop a tick from attaching, but should kill the tick within 48 hours to prevent disease transmission.

Borrelia burgdorferi (Lyme disease) is a spirochete transmitted by deer ticks (Rhipicephalus sanguineous) that is zoonotic, i.e. it can be transmitted to different species, including humans. This tick is by far the most common species found in the UK. Lyme disease causes painful swellings of the joints – or sometimes just painful joints – at different times and in different places. This causes a shifting lameness and arthritis, and is extremely painful. It can also cause high temperatures, marked lethargy and malaise, inflammation of the heart, and in late stages, damage to the brain and central nervous system.

Babesia canis is a piroplasm that is transmitted from brown ticks (Dermacentor reticulatus) to dogs. It causes a severe infection of the red blood cells and marked anaemia – although effective treatment is available, it can still be fatal to some animals. Affected dogs become very suddenly pale, with dark or bloody urine, and may collapse. This is a commonly transmitted disease in this species of tick.  Fortunately, this type of tick has been rare in the UK, but has risen in numbers in recent years.  The increase in population is possibly because of ticks being imported on dogs returning from Europe. It is essential that your pet is treated with an effective treatment before, during and after travel, to prevent such diseases from becoming common in this country.

Lungworm is a broad term applied to several worms: Crenosoma vulpis, the fox lungworm, Aleurostrongylus abstrusus, the cat lungworm, and Angiostrongylus vasorum, the dog lungworm.  Fox lungworm can also affect dogs. These are all types of worms that live in the airways of the lungs and pulmonary system. They are very different to heartworms found in America – which live in the vessels of the heart – caused by Dirofilaria immitis and transmitted by mosquitoes.

Both dog and fox lungworms are transmitted in the slime trails of slugs and snails: your pet does not have to eat a whole slug or snail to contract lungworm – only to ingest larvae in infected slime.  If your pet ever licks or chews grass or other plants, they will be at risk.

Cat lungworm is transmitted through birds and rodents instead of slugs and snails – cats do not have to ingest the entire animal, but do have to have contact with infected tissues or droppings.

The larvae of lungworm are eaten, and make their way via the lymphatics and major vessels into the right ventricle of the heart, and from there into the pulmonary artery. This is a low-pressure vessel through which deoxygenated blood travels from the heart to the lungs. The larvae develop into adults, which then lay eggs in the smallest blood vessels in the lungs, the pulmonary capillaries. When these hatch, the larvae make their way into the smaller airways – the bronchioles – and into the air sacs called alveoli in the lungs. This is where gas exchange usually takes place. The presence of the larvae induces coughing – the larvae are coughed up, swallowed by the host, and passed in the stools of the host. These are then eaten by unsuspecting slugs and snails – or birds and rodents – and the cycle continues.

Lungworms cause coughing, lethargy, high temperatures, and tendencies towards bleeding. Affected pets may have a hacking cough, may be reluctant to exercise, be lethargic, or bleed for longer if they receive a cut. Some pets, particularly cats, may show marked respiratory distress, as a result of the huge inflammatory response to the larvae in their lungs.

Again, we can never prevent your pet from picking up any of these lungworms, so we rely on regular treatment with a suitable product active against the L3 and L4 stages of larval development. If your pet is showing possible signs of lungworm, they may have a large burden of larvae in their lungs. In this case, treatment can make the inflammatory reaction worse. We may therefore recommend treatment within the clinic itself, so that we can provide life-saving treatments, if needed.

Encephalitozoon cuniculi – this is a protozoan transmitted though the urine of infected animals, and is common in the UK. Although we classically associate this parasite with rabbits, it can also rarely affect guinea-pigs, rodents and larger mammals.

• cuniculi travels from the intestines to the kidneys and the nervous system, so can result in a myriad of clinical signs depending on the affected nerves. Often, the first things to be noticed are a head-tilt and an increase in urine output or a dirty bottom. Your bunny may also start turning in circles, or shuffling on its hind legs. In some cases, rabbits may develop severe weakness (paresis) or even paralysis of the hind limbs. Others may become deaf or experience convulsions. Eventually, E. cuniculi makes its way to the brain, at which point treatment is ineffective and the disease often fatal.

In the early stages, and when the protozoan is in the peripheral nervous system, this can be treated with fenbendazole. The treatment course is daily and prolonged – a minimum of 28 days is required to be effective. However, the parasite may never be fully cleared from the system, and any damage to the central nervous system is irreversible.

We recommend all new bunnies are treated with a 28-day course, because young rabbits can have picked this up from their mothers. For bunnies showing no signs of E. cuniculi, we recommend regular thorough cleaning of the environment – this parasite is easily killed after 30 seconds of contact with 1-10% bleach. Always ensure that any areas in contact with bleach are thoroughly rinsed afterwards.

Tapeworm affects many different animals and comes in many different forms, but all tapeworms are so-called because they develop in roughly rectangular segments called tapes, that join together like a long piece of tape! These are zoonotic – you can also pick them up.

Tapeworms live in the intestines, and attach to the intestinal wall with their mouthparts. Initially, the worm is very small, but as it grows, it develops more and more segments. They can grow to many metres in length! Each new segment carries lots of eggs, and when these are ready to be shed, the segments simply detach and are passed in the stools. These resemble grains of rice in the stools, and can be seen with the naked eye – they are about rice-size. The segments then break down and the eggs are released onto the floor, for something else to come along and eat.

The passage of these segments can be very irritating, so infected pets may lick a lot at their bottom. As with all worms, these parasites absorb nutrients that your pet should be receiving, so your pet may lose weight and be very hungry.

With the exception of those animals with persistent flea infestations, tapeworms are thankfully not as common as roundworms.  We usually recommend a suitable treatment every 3 months, but this will depend on your pet’s lifestyle – your vet can advise you of what will be suitable.

Roundworms – there are many, many different species of roundworm, and different worm species infect different animal species. There would not be enough time to go through all of them here, so we shall focus on a few salient points.

Roundworms can affect not only dogs and cats, but also birds, reptiles, small mammals, and everything in between – including people. Some of these species can cause blindness if contracted by children, so teaching good hand hygiene practices is essential.

Some of these worms sit passively in the intestines, absorbing nutrients that their host should be receiving. This generally results in weight loss and hunger, although weight gain and a pot-bellied appearance is also possible once high burdens are achieved. Some worms actively feed, using teeth to attach to the intestinal wall. These worms feed on blood, so can cause significant irritation in the intestines e.g. pinworm and hookworm.  Infected pets may demonstrate a reduced appetite, pallor of the gums, and reduced passing of faeces (because of the discomfort this causes).

High burdens of worms may cause obstruction of the intestines in some cases. These pets may have vomiting, reduce or even stop passing stools, may be become distended in their abdomens, and may be very ill.

Roundworms pass their eggs into the stools of their host, and at times even come out in stools themselves. Typically, they resemble noodles and can be seen – the size will vary depending on the type of worm. The passage of eggs, larvae and adults can be very irritating, so some pets may lick or chew at their bottom.

We cannot prevent pets from picking up roundworms – they can be ingested through contaminated carcasses or contaminated ground. However, we recommend regular treatment with a suitable product to clear any worms that are present. Treatment may be as regularly as every 2 weeks for pets with heavy burdens, every month for pets patrolling contaminated areas, or every 3 months for pets such as insectivorous reptiles.  Your vet or veterinary nurse can advise on a suitable regime for your pet.

Trichomonas gallinae – this is a common protozoan parasite of wild birds and is a threat to any outdoor birds such as chickens, turkeys, raptors, or aviary birds. It is spread in the droppings of infected birds via contaminated food or water sources.

Trichomonas causes the development of plugs of material at the back of the throat and in the gullet. Typically, birds hide all illnesses for as long as they can, so early signs may simply be fluffed up feathers.

Affected birds find it difficult to swallow, so may lose weight and stop laying eggs, and may also dribble. This can be noticed by having wet feathers around the beak and face. As the plugs grow, birds also struggle to breathe.

This parasite can be difficult to fully clear. Surgical removal and concurrent treatment is required, but is not always effective. Infected birds may not survive. It is extremely important to thoroughly clean all food and water containers regularly, and prevent these from coming into contact with wild birds.

Mites come in all shapes and sizes, but are mainly host-specific. Bird mites affect birds, reptile mites affect reptiles, dog mites affect dogs etc. Mites can either be superficial, living on the dead skin layers, or deep, living in the deeper skin layers, or can occupy hair follicles or feather shafts.

These parasites can move around, and are more than happy to swop hosts, if the opportunity presents itself. Many can survive in the environment – such as on fence posts or cage furniture – and are very readily passed between animals.

Burrowing mites can cause extreme pain, whilst all mites cause intense itchiness. Pets may scratch, lick, chew or bite at their skin regularly, and may even make themselves bleed. Burrowing mites can cause profound anaemia in high levels, as can red mites in chickens (which do not stay on the host during the day, but come out to feed at night).

We recommend regular treatment with products that remain in the skin layer. We cannot prevent mites from finding your pet, but we need to ensure that if your pet is bitten by a mite, the product present in the skin kills the mite rapidly – before it can lay eggs. Treatment of the environment is also essential in the case of an infestation, and this can vary depending on the species of animal infected and the causative mite.

Lice – like mites, these come in all shapes and sizes, and affect all different species. However, lice are usually not only species-specific, but also host-specific.  Lice cannot survive in the general environment, so do not frequently move between hosts (although this is possible in some cases).

Different species of lice may either bite or suck at their hosts. This causes profound irritation, both from the movement of the lice themselves, and from the damage they cause. Affected pets may be seen frequently biting, chewing or licking at their skin or feathers.

We recommend regular treatment with products that remain in the skin layer. We cannot prevent all lice, but we can ensure that residual product present in the skin kills the lice rapidly when they feed. Although treatment of the environment is in a different manner to that for mites, we recommend thorough cleaning of any infected areas. Hay, straw and similar materials can be ideal warm areas for lice, so should be completely removed and a new source used (in case the previous bag/bale was infected).