The Common Parasites Of Our Pets

parasites

The common parasites of our pets may be divided into ecto- ( on the outside ) & endo- ( on the inside ) parasites.

Ectoparasites

Fleas – each species of animal has its own species of flea, but a hungry flea won’t be fussy & will be happy to feed on anyone, including a human! Although we tend to think of fleas as being a seasonal problem, more prevalent in summer, some of the worst flea infestations can occur in winter, as any fleas brought into the house can go through their reproductive cycle rapidly in the warmth of the central heated home.

It is only adult fleas that will feed on a pet. They also lay eggs while on an animal, & these eggs will fall off haphazardly in a ‘pepper shaker’ effect with movement, distributing the potential of a new population of fleas wherever the pet wanders or rests. The eggs will hatch into larvae, which hide away in cracks & crevices, feeding on organic debris and growing until they are ready to pupate, emerging as adult fleas to start the cycle all over again. From egg to adult takes on average about a month, but in ideal conditions of temperature & humidity the entire cycle can be completed within a fortnight. So a relatively minor problem can quickly escalate and be more difficult to get under control.

Aside from being an itchy nuisance, fleas can pose more serious problems for some pets. When they feed, fleas inject their victim with saliva that contains an anti clotting agent, so they can take on a full blood meal. Some animals may become sensitised to theses proteins and develop an allergic reaction known as flea allergy dermatitis. And in very small puppies & kittens, the flea burden can be so severe as to cause a life-threatening anaemia. It is also possible for fleas to spread certain blood parasites and a species of tapeworm.

Luckily, we have a number of very effective flea treatments, including spot ons such as Advocate & Stronghold, & oral treatments eg Bravecto. There is even an injection ( Program) which doesn’t kill fleas but makes them sterile, preventing eggs from hatching & so steadily decreasing the local flea population. And household sprays ( eg Indorex ) can be very helpful for dealing with environmental control in the house. It is worth remembering that in the face of a severe outbreak, no single product will be fully effective, a combination of control on the pet(s) & in the environment will be required. And obviously prevention is better than cure!

Ticks – these tend to be found in areas with a population of sheep or deer ( or hedgehogs!), but again ticks will attach to any species, including humans, to feed. Ticks will wait in the undergrowth, sensing the presence of a possible host by vibrations from movement. When they attach they can be very tiny, burrowing their mouthparts into the skin to start feeding on blood. Over the course of 48 hours the body of the tick swells, & once full, they will drop off to digest their meal then wait for their next host.

Unfortunately we currently don’t have any medications that are fully effective at repelling ticks, but there are a number that will cause them to die & drop off once attached eg Bravecto, Advantix.

It is possible to remove ticks with a special hook which allows rotation of the head out of the skin, but it is important that no mouthparts are left in the skin as they can cause an inflammatory reaction and infection.

It is best not to try removal with any ‘home remedies’. We know that ticks that become ‘stressed’, or are approaching the end of a meal, may regurgitate some stomach contents back into the host’s blood stream, & these can contain parasites carried by the tick such as those causing Lymes Disease & Babesiosis.

Any concerns about the appearance of a tick bite ( typically raised, reddened skin ) should be brought to the attention of the vet ( or to the doctor, if on a human – a red ‘target’ lesion around the bite can indicate early Lymes Disease) -antibiotic treatment may be required.

Sarcoptes ( Fox Mange ) – This type of mange is contagious & can be caught from contact with an infected dog, or even by brushing through areas frequented by infected foxes. It is extremely itchy, causing inflammation of the skin & fur loss. Humans can also be reactive to the mites that cause it.

Diagnosis is by elimination of other causes, & mites may be visible under the microscope in skin scrape samples taken from affected areas. However, a negative scrape does not rule out mange, as it can take only a few mites to cause the reaction.

In any suspected case treatment ( eg Symparica ) will be started to treat against the mites, plus any symptomatic treatments required to ease secondary infection & soothe the skin.

Although Sarcops is an unpleasant & potentially serious disease, it can be treated effectively.

Demodex – This is also caused by a type of skin mite that is present in the skin & hair follicles of many dogs ( often picked up in early life from their mum ), but can cause localised or generalised skin disease if the immune system is immature or compromised. Again, diagnosis can be made by examining skin scrapes under the microscope, and treatment is generally via oral medications, but previously involved weekly shampooing with products which opened the hair follicles & killed the mites.

Endoparasites

Roundworm ( Ancylostoma, Toxocara, Toxascaris, Trichuris, Thelazia ) – These intestinal worms can be transmitted from mum to babies in the womb, or by contact with contaminated faeces. They may be seen in vomit or faeces in infected animals, with the appearance of short pieces of spaghetti. Regular worming with an oral or spot on product, or faecal worm egg counts are advisable. Although we cannot prevent worms, regular treatment will get rid of any current worm burden.

In puppies & kittens, worming every month until 6 months old is recommended as they are more vulnerable to worm related illness, with symptoms such as vomiting or diarrhoea, poor growth or weight loss, poor hair coat & a pot bellied appearance. In adults, treating every 3 months will generally be adequate unless evidence of infection is seen.

There are particular concerns regarding zoonotic Toxocara infection of humans, especially children. Transmitted via contact with dog faeces, this can have serious consequences, including loss of sight.

NB Thelazia, known as the eye worm, is not currently endemic in the UK, but has on rare occasions been found in imported dogs. It is transmitted by the fruit fly, & develops in the tissues on & around the eyes.

Tapeworm ( Dipylidium, Taenia, Echinococcus, Mesocestoides ) – Most tapeworms are transmitted via infected meat, so tend to be seen more commonly in cats who hunt. Tapeworm segments may be seen in the faeces, about the size of rice grains. The head of the tapeworm attaches to the lining of the intestine, so it would be rare to see an entire worm passed, but they can be several inches long. Dipylidium has the flea as its intermediate host, & may infect pets who ingest fleas when grooming.

Again, routine worming with a suitable product is advisable.

Lungworm ( Angiostrongylus ) – Lungworm is a potentially dangerous parasite that develops within the heart & lungs of pets, causing coughing, breathing problems, poor exercise tolerance & problems with blood clotting. It can be caught by ingesting slugs or snails carrying the lungworm larvae, so dogs that scavenge are at increased risk, but any dog could accidentally ingest tiny slugs on a toy or from their fur. Symptoms can start to appear within a month. Diagnosis may be made from the history, symptoms and faecal analysis.

There is a lungworm map available online which is constantly being updated to highlight prevalence of the disease in different regions of the UK. SE England & Wales are most significantly affected at present, but lungworm has been identified in other areas. Prevention is via monthly spot on ( Advocate ) or tablets ( Milbemax ).

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