Parasitic infestations

External parasites (ectoparasites), including arthropods (fleas, ticks, lice, harvest mites and mange mites) or fungi such as yeasts and ringworm, can have a profound effect on the dog’s skin and coat. Internal parasites (endoparasites), bacteria and viruses, which are sometimes transmitted by fleas, ticks or mosquitoes, may have serious consequences for the dog’s health and cause infectious diseases, some of which are contagious. Certain diseases can be prevented through vaccination.
External parasite infestations mainly affect the skin and coat. They can cause eczema, pruritus (itching) or significant hair loss. Internal parasites are primarily encountered in the gastrointestinal tract (oesophagus, stomach and intestines), but can also infest the lungs and bloodstream.

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> Ectoparasites

Fleas

These are wingless insects with a laterally flattened body. Dog and cat fleas belong primarily to the species Ctenocephalides felis other species may be seen, such as Ctenocephalides canis. Only the adult fleas infest mammals, while the other larval stages and cocoons (nymphs) stay in the environment. These are essentially found in areas that are frequented by dogs or cats. It is estimated that at any given moment, adult fleas present in the coat represent less than 5% of the total flea population. Fleas are highly prolific: a female lays 25 eggs per day and almost a thousand in her lifetime. The eggs do not stick to the dog’s coat, but fall to the ground and collect in rugs, carpets, wooden floors, etc. After hatching, the larvae undergo metamorphosis and become nymphs; then, when conditions are favourable, they emerge as adults and become parasites on an animal. The adult flea pierces the dog’s skin with its mouth parts and then sucks the blood using its proboscis (feeding tube) after inoculating it with its saliva, which has anticoagulant and allergenic properties. The presence of fleas can be determined by the excrement that they leave behind: tiny black pellets on the animal’s skin, particularly in the dorsal lumbar region. These pellets consist of blood which has been swallowed and partly digested by the fleas.

© ENVA

Fleas cause many diseases. They are a direct pathogen, although usually not a serious one, as they merely make the dog itch. However, dogs can develop flea allergy dermatitis (FAD), which causes significant pruritus resulting in hair loss and even sores from scratching; the lesions are primarily localised to the back, loins and base of the tail. The manifestations of this disease are less common during winter, since fleas are less active in the external environment. They are also indirect pathogens, i.e. they transmit other pathogenic agents: bacteria (including the bacterium responsible for bubonic plague in humans) and a tapeworm that infests the gastrointestinal tract (which is transmitted when adult fleas are ingested by the animal).

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The why and how of the war against dog fleas

The only way to combat a parasite effectively is to understand its lifecycle in order to break it at the most sensitive point.

Larvae hide from the light, meaning that they can be found under rugs or cushions, behind the skirting boards, between floorboards, etc. After one or two weeks of life, the larva changes into a cocoon, which is very resistant to flea treatments and can survive this way for up to five months. The presence of animals or humans and the vibrations that they create as they move about triggers the hatching of the adult from the cocoon. When animals or people move into a house that has been uninhabited for several months, a large number of cocoons may hatch all at once, leading to an infestation of fleas within a matter of hours: so-called “parquet fleas” are in fact a massive emergence of adult Ctenocephalides felis. The adult then jumps onto a cat or dog (usually) and bites the animal to feed on its blood. The females are the most voracious and can eat fifteen times their own weight in blood (seventy females can consume one millilitre of blood per day!). If nature calls while a female flea is feeding, the flea deposits “flea dirt”; these small black pellets can be seen in the animal’s coat and leave a deep red stain when placed on wet paper.

In addition to siphoning off blood, fleas frequently cause allergies and can also transmit a tapeworm to dogs and cats, a phenomenon often found in adult carnivores.

Most of the flea treatments that are applied to the animal do limit the number of fleas, but they are not sufficient to eliminate all of them because there are often large numbers still lurking in the environment. Two treatments are usually recommended. The purpose of the first treatment, an insecticide, is to kill all the adult fleas on the dogs and cats living in the area to be treated. This is achieved with antiparasitic agents in a spray, “spot-on” or tablet format. Flea-collar and powder formulations have limited efficacy. A “spot-on” is a medication that is deposited on the animal’s skin in the form of a few drops of a very concentrated solution. This solution then diffuses over the entire body of the animal and makes it possible to kill the fleas as they feed. This treatment should be repeated every one to two months depending on the product used. The second treatment is with an insect growth regulator or IGR, which blocks the flea’s lifecycle in the environment. Insect growth regulators have the advantage of being completely harmless to domestic animals and humans.

These insect growth regulators are administered either by applying them directly to the animal (where they act because they are ingested by female fleas who transmit them to their offspring) or by application in the environment (direct contact with the flea larvae). Before applying this treatment to the environment, it is important to dust and clean all of the areas to which the animal has access (don’t forget the vacuum cleaner and the cupboard where it is kept, which can become “flea nests”), then treat the surfaces that are liable to harbour fleas using an insect growth regulator (usually combined with an insecticide). It may also be necessary to treat the garden in summer months, although only in shady areas where the dogs and cats lie down (the products used should be resistant to UV light). There are many effective insecticides and insect growth regulators on the market, each with their own advantages and limitations.

The results obtained are usually good, but are reliant on how the treatments are applied and how often they are used.

Ticks

These are large acarina (2 to 10 mm) belonging to the Ixodides family. They have three life stages: larva, nymph and adult. Ticks present significant sexual dimorphism: the abdomen of females is highly distensible, unlike that of the males. Their body is red-brown in colour and flat, except after a meal of blood when they become globular. At each stage of their lives these parasites attach themselves to a vertebrate host; they are strictly haematophagic (feed on blood ), except for the males of certain species, which do not feed at all. Numerous species of tick can infest dogs, but the most commonly observed are Dermacentor reticulatus and Rhipicephalus sanguineus (the most common in Europe but not in the United States). The latter are specific to dogs and try and attach themselves to this host at every stage of their life (larva, nymph and adult). Ticks attach to a dog’s skin, preferring the most delicate areas. They use their mouth parts to pierce the skin and inject their saliva, which solidifies into a very strong attachment point. The tick can then enjoy its meal of blood, after injecting more saliva with anticoagulant and vasodilating properties. Fertilised females drink large amounts (as much as several millilitres). Larvae, nymphs and other adults take only a single meal. Once the tick has finished its meal, another type of saliva is used to dissolve the attachment point so that the tick can drop off. A free-living stage may follow the parasitic phase, depending on outside conditions. This free-living stage of the tick’s life cycle is much longer than the parasitic stage.

Ticks mate on their hosts as the female feeds, which accelerates its food intake. Once it has finished its meal of blood the female falls to the ground, then after a few days it lays several thousand eggs and dies. Depending on the environmental conditions, the eggs incubate for a variable period from a few weeks to a few months and then hatch. The larvae leave the egg and climb up the nearby vegetation, where they wait for the passage of their future host. They attach to the host and take their first meal, which may take several days, before dropping to the ground again. After a period on the ground, the larva moults and becomes a nymph. The process repeats itself: the nymph attaches to the host and feeds, drops to the ground and moults again to become an adult male or female. The complete cycle is quite long, considering that the tick must attach to three hosts: if conditions are not absolutely ideal, the entire life-cycle may take up four years in some species of tick. Furthermore, not all eggs reach adulthood because they may be destroyed or ingested at any stage of development by various animals, particularly during the free-living stage.

Ticks play a significant direct pathogenic role, firstly through the irritation provoked by the penetration of the tick and its saliva. After the tick has fallen off, the skin is weakened, so that the lesion caused by the fixation may become the point of entry for bacteria, leading to secondary infections. The blood meal deprives the dog of a small amount of blood, which can lead to anaemia in the event of a massive infestation. Finally, the presence of ticks on the dog, as with other animals or man, may have a toxic action, both local and systemic. For example, in Australia there is a disease known as tick paralysis, which is caused by Ixodes holocyclus. Without treatment this leads to death due to paralysis of the respiratory muscles.

The presence of ticks also affects the dog’s immunity. At the next infestation the dog may become hypersensitive with a severe reaction (pruritus) at the fixation point, which make it hard for the tick to attach, and progressively results in a reduction in the number of ticks attached. The dog develops an acquired immunity. Ticks can also transmit various pathogenic agents that are responsible for disease, either from a female to its offspring or from one stage of development to the next. Ticks are responsible for the transmission of:

- Babesia canis, the agent responsible for babesiosis (also known as piroplasmosis), which is transmitted by Dermacentor reticulatus and Rhipicephalus sanguineus.

- Hepatozoon canis, responsible for hepatozoonosis, transmitted by Rhipicephalus sanguineus following the ingestion of the latter.

- Ehrlichia canis, the agent responsible for ehrlichiosis, transmitted by Rhipicephalus sanguineus in tropical and temperate regions.

- zoonoses (diseases which are transmissible to man) such as eruptive Mediterranean fever, present in southern Europe, Africa and India due to transmission of Rickettsia conori by Rhipicephalus sanguineus.

© Diffomédia/Royal_Canin

Ticks play a role in the transmission of numerous other bacterial diseases as well as viral diseases and helminthiasis. These include Lyme’s disease, which is caused by a bacteria (Borrelia burgdorferi) transmitted by Ixodes ricinus.

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How to remove ticks

If the dog is not heavily infested, the ticks may be removed one at a time with a special, veterinary-designed hook that can be used to extract the tick without squeezing it or breaking off the mouth parts, or by using a felt-tipped applicator impregnated with cypermethrin. It is essential to remove all of the mouth parts to prevent an abscess forming at the point of attachment. Always inspect your dog carefully after returning from a walk in tick-infested areas (long grass). The ticks should be removed as soon as possible after they latch on, as this is the best means of preventing tick-borne illnesses.

If the dog is heavily infested, it should be washed in pyrethroids, or amitraz, which will kill all of the ticks.

To avoid infestations in kennels or other group situations, the floor and walls should be covered with cement, and an appropriate powdered insecticide should be used. A vaccine is also available against piroplasmosis; this is effective for six months and is designed to prevent this parasitic disease in dogs which frequent areas with a significant tick population (e.g. forests).

© Diffomédia/Royal_Canin
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What is the best way to protect my dog against ticks and fleas?

Treatment of fleas must be directed at the adults on the pet and the eggs and larvae in the environment. There are numerous products that can be applied to our pets in the form of spot-on products, sprays, shampoos, dips and collars and these kill the adult fleas. Together with treatment of the pet, environmental control is required and here we need to use environmental sprays on the carpets and rooms in the house where the animals spend most of their time. Ticks are best controlled by using collars, spot on products, dips and sprays and they can also be removed manually.

Is it true that dogs can get tick bite fever even if I use a tick and flea product on them?

Yes this is true. Application of products onto the pet dramatically decreases the risk of infection but sometimes a tick may take a blood meal and transmit the disease before being killed and falling off the dog.

© Carter

Dr. Alain J. Carter
BVSc (Hons)
MMed Vet (Med)
South Africa

Demodectic mange

Demodectic mange is a parasitic dermatosis caused by infection of the hair follicles with a microscopic vermiform mite: Demodex canis.

It causes patchy or diffuse alopecia and significant erythema (redness) and there is a risk of secondary bacterial infection. It especially affects young dogs through contamination during the first few months of life (puppy-mother contact) while nursing. Many dogs are carriers of the infection (approximately 85% of the population) but only a few develop demodectic mange. The disease often appears between three and twelve months of age. Moist skin and poor breeding conditions are favourable conditions for Demodex canis.

Dry demodectic mange may take several forms:

- Localised form: limited number of nummular (circular or coin-shaped) lesions often localized around the face (small patches around the eyes) and on the limbs.

- Generalised form: this carries a more guarded prognosis. Irregular hair loss in roughly oval patches, erythema, hyperpigmentation then hyperkeratosis (thickening of the skin) and seborrhoea (increased production of sebum) which causes a rancid odour.

Treatment is long and requires the use of amitraz or milbemycin, which are prescribed by the vet.

Demodectic mange may also become secondarily infected, resulting in pustular demodectic mange in which in addition to the lesions described above there are pustules, crusts and oozing skin. The dog loses weight. Death may occur within a few weeks if no treatment is provided.

© Diffomédia/Royal_Canin

Sarcoptic mange

Sarcoptic mange or scabies is a parasitic dermatosis that is highly contagious to humans and is characterized by intense pruritus.

© Diffomédia/Royal_Canin

Symptoms:

The skin is erythematous (red) with small papules (spots) on the limbs and lower parts of the body, axillae, groin and ears. Lesions initially appear around the edges of the ears and on the point of the elbow. It causes intense pruritus (scratching), which results in alopecia and crusts.

Treatment:

All affected dogs and those that have been in contact with them should be isolated and treated with an anti-parasitic treatment. In man the disease causes small, red papules similar to insect bites on the arms and legs and very intense itching especially at night (due to warmth in the bed). Recovery is only possible once the dog has been treated.

Pseudo-mange

Cheyletiellosis or “walking dandruff” is a highly pruritic dermatitis caused by the presence of microscopic mites that live in the animal’s fur. They cause significant desquamation (peeling of skin in scales) in the dorsolumbar region and on the ears. Pruritus is variable. Hair loss is seen where the dog has scratched itself. This disease is highly contagious in a kennel and is transmissible to man (pruritic papules on the arms and trunk).

© Diffomédia/Royal_Canin

Pediculosis

Pediculosis is an infestation of lice. Two species of lice infest the dog: one chewing louse, Trichodectes canis, and one sucking louse, Linognathus setosus. Lice are host-specific, permanent parasites. They cause severe skin irritation resulting in pruritic dermatitis with desquamation. The nits (lice eggs) stick to the base of the hair shaft and are easily visible.

The head (ears) and neck are the most affected areas. Long-haired breeds are most susceptible (Cocker Spaniels, Spaniels.

© ENVA/Diffomédia/Royal Canin

Trombiculosis

This parasitosis is caused by the larvae of microscopic mites called harvest mites and is restricted to fine skinned areas of the body: ears and the extremities of the legs. Powdery, orange-coloured clusters are seen on the dog’s skin along with marked skin irritation: trombiculosis is a highly pruritic dermatitis.

Ringworm (Tinea)

© ENVA/Diffomédia/Royal Canin
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The lesions present localised, regular or diffuse areas of hair loss

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Ringworm is a cutaneous mycosis (fungal growth) that affects the skin and nails. The lesions present localised, regular or diffuse areas of hair loss. Erythema and more or less intense desquamation is observed. Ringworm does not cause pruritus and has no effect on the general health of the dog, but it is highly contagious from dogs to other dogs, cats and humans. It is transmitted through direct contact with infected animals or via contact with fungal spores on contaminated bedding and grooming materials.

There are two different clinical presentations:

• Dry ringworm:

Often localised, the alopecic lesions are regular and well demarcated (like a coin). The skin is erythematous, especially at the edges of the lesions and is covered with greyish scales with a powdery appearance. The lesions are more common on the upper and anterior regions of the body.

• Suppurative ringworm:

Localised or diffuse forms, sometimes forming a raised, erythematous and oozing plaque of one to two centimetres in diameter, which is called a kerion.

Treatment for ringworm is long and requires good hygiene and specific local and systemic treatments for at least one month before any improvement can be expected.

> Internal (gastrointestinal) parasites

Oesophagus and stomach

Spirocerca lupi is the main parasite that infects the oesophagus and stomach in dogs; it is a nematode that is usually found in the oesophageal wall and less commonly in the stomach or even in the wall of the aorta.

These parasites cause a serious disease that is endemic in tropical countries, northern Africa and southern Europe. Dogs become infested by ingesting the intermediate hosts, usually coprophagic Coleoptera (dung beetles) but also small vertebrates that become contaminated when they eat dung beetles.

Diseased animals show oesophageal (regurgitation, sometimes inability to swallow) and gastric symptoms (repeated vomiting, increased thirst). Respiratory difficulties may be observed when the parasite infests the wall of the aorta. Treatment is very difficult, involving injectable anthelminthics such as ivermectin. Given the wide variety of hosts that are capable of hosting the larvae of the parasite and that are responsible for the infestation in the dog, totally effective prevention is almost impossible.

Small intestine

© Diffomédia/Royal_Canin

Several species of worms infest the small intestine of the dog, principally the strongyles, ascarids and cestodes.

Strongyloidiasis, or hookworm infestation, is mainly caused by Uncinaria stenocephala,Ancylostoma caninum, which is particularly common in very hot regions, and Ancylostoma braziliense,in tropical countries. These parasites primarily affect animals living in groups. Ancylostoma causes severe anaemia – often referred to as pack dog anaemia – whilst Uncinaria causes diarrhoea. Larvae of the Ancylostoma genus penetrate the skin or are ingested by puppies along with the bitch’s milk. The infestation has several stages corresponding to larval migrations within the body. It begins with a cutaneous phase: small lesions appear on the dog’s abdomen or between the toes, which disappear spontaneously within about ten days. The adults develop in the small intestine, which causes gastrointestinal symptoms such as alternating diarrhoea and constipation, followed by the onset of persistent diarrhoea with a foetid odour. Finally, the dog’s general health deteriorates due to anaemia in the event of infestation with Ancylostoma. This parasite is highly haematophagic: each adult ingests around 0.2 ml of blood per day; with infestations of up to several hundred parasites this results in the loss of tens of millilitres of blood each day. In severe forms, the disease may prove fatal, whilst in milder forms spontaneous recovery is possible.

They also affect the immune system. In such cases the initial skin reaction on re-infestation is more marked, which hinders larval migration. Dogs can therefore develop a degree of resistance to these hookworms.

The primary means of prevention in group housing situations is to disinfect the entire area. Pregnant bitches can be given preventive treatment with fenbendazole, which destroys the larvae. Puppies can also be treated once a week from the age of 10 to 45 days, then again at 8 weeks and 12 weeks in areas where these parasites are endemic.

Small intestinal parasites include the nematodes (roundworms) from the Ascaris family (e.g. Toxascaris leonina) and the Toxocara family (Toxocara canis; the latter can be transmitted to humans and can cause serious disease notably ocular disorders. These parasites primarily infest young dogs less than a year old. The puppies ingest embryonic eggs in their drinking water or food, or the eggs are transmitted from the mother to the puppies either in utero or via the milk. Dogs in poor general health are more susceptible, particularly those suffering from certain nutritional deficiencies. Massive infestation causes generalised symptoms such as slow growth, weight loss and a high mortality rate in three- to seven-week-old puppies that were massively infested before birth.Toxocara canis may cause the dog to cough due to the migration of the larvae through the heart and lungs before returning to the intestine via the trachea. Puppies display primarily gastrointestinal symptoms: diarrhoea interspersed with periods of constipation, vomiting (to get rid of some of the parasites) and a distinctly pot-bellied appearance. Complications may also arise in the form of intestinal obstruction (by a clump of worms) or even intestinal perforation leading to haemorrhage or peritonitis. The parasites also ingest blood and some of the intestinal contents, both of which contain elements essential for the puppy’s growth. Diagnosis is usually straightforward: the puppy’s overall health is poor, its abdomen distended and it sheds parasites in its stools or by vomiting. Analysis of a stool sample can sometimes provide the diagnosis. Many parasiticides are available, the most effective being the benzimidazoles and macrocyclic lactones. Preventive measures include the systematic treatment of young dogs and their mother. Dogs should be treated every month up to six months or one year of age, then four times a year. This treatment should be adapted as a function of the conditions in the breeding kennel. It is extremely difficult to destroy eggs in the environment, as they are highly resistant.

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They affect dogs of all ages, leading to significant anal pruritus.

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Cestodes can also invade the small intestine. These tapeworms, such as Dipylidium caninum, are transmitted via the ingestion of fleas. They affect dogs of all ages, leading to significant anal pruritus which causes the dog to rub its bottom along the ground.

Associated gastrointestinal symptoms include the elimination of segments of the parasite (which look like grains of rice) in the stools; there may also be diarrhoea. Re-infestation is common and facilitated by gregarious living conditions due to the difficulty of eliminating all of the fleas. The parasites ingest minimal quantities of blood.

© Diffomédia/Royal_Canin

Their main effect is to cause irritation and swelling of the anal glands.

Prevention is primarily based on eliminating the intermediate hosts, both fleas and, to a lesser extent, lice. Use of specific anti-cestode treatments in infested animals, such as praziquantel, is then recommended. Multi-purpose anthelminthics such as nitroscanate can also be effective. There are many other less commonly seen cestodes which can have serious consequences in other mammals as a result of the development of larvae of the parasite in these species. Two from the Echinococcus species, Echinococcus granulosus and Echinococcus multilocularis, can be transmitted to man and cause serious disease.

© ENVA/Diffomédia/Royal Canin
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What are the benefits of preventative worming treatment?

Everyone knows the benefits of vaccination and that vaccines are a preventative treatment for pets.

For parasites it is interesting to see that in fact many parasitic illnesses can be prevented by giving the dog a simple monthly preventative treatment.

Not all parasites live in the same regions. For example, in certain areas mosquitoes are vectors of heart worm. So if a dog lives in or visits these regions for a holiday, it must be given a preventative treatment to avoid a life-threatening disease.

© Pérez Tort

Gabriela Pérez Tort, D.V.M.
Veterinary Faculty of Parasitology and Parasitic Diseases
University of Buenos Aires (Argentina)

Large intestine

This section of the gastrointestinal tract, namely the caecum and colon, is mainly infested with nematodes of the genus Trichuris vulpis.Dogs become infested by ingesting eggs present in the environment. Young dogs between 8 and 18 months of age seem to be the most susceptible. A massive infestation leads to symptoms such as diarrhoea (which can be bloody), anaemia and obvious weight loss. These whipworms siphon off blood, leading to blood loss, and cause lesions in which bacteria can develop. Diagnosis requires faecal analysis, which reveals the presence of the parasite eggs in the dog’s faeces. Treatment is by administration of benzimidazoles or macrocyclic lactones. However, re-infestation is extremely common so the owner should ensure that the facilities are clean and the food is hygienic.

Babesiosis

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In Europe the vectors are ticks from the Dermacentor reticulatus and Rhipicephalus sanguineus species.

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Babesiosis is caused by a protozoan (single-celled) parasite known as a piroplasmid, namely Babesia canis. During its life cycle, this parasite must pass through a vector host before transmitting the disease from one dog to another. In Europe the vectors are ticks from the Dermacentor reticulatus and Rhipicephalus sanguineus species.

Parasite development in dogs passes through several stages corresponding to the different stages of the parasite’s lifecycle. Initially, the parasite is a very simple, circular organism known as a trophozoite. It enters the red blood cells and feeds on their haemoglobin, which it digests. The trophozoite undergoes asexual reproduction (simple cell division).

© Diffomédia/Royal_Canin

The nucleus of the cell divides first, followed by the membrane and cytoplasm (the liquid contained within the membrane). The division results in two droplet-shaped daughter cells, or merozoites, which are still inside the red blood cell. There may be more than two cells inside one red blood cell. Usually the red blood cell is destroyed after division and the parasites are released into the bloodstream. Each merozoite quickly attaches to another red blood cell, enters it, and forms a trophozoite. Some merozoites stop producing trophozoites and produce gametocytes. This is the first stage of sexual reproduction in the parasite.

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Highly-selected breeds such as Cocker Spaniels, Spaniels, Yorkshire Terriers and Dobermanns are more usceptible than others. Puppies are more vulnerable than adults.

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If the tick, an intermediate host, takes a meal from an infested dog, the red blood cells it ingests are destroyed in its intestine, as are the trophozoites. Only the gametocytes remain, which then become gametes in the intestinal wall. Two gametes fuse, forming an egg, or zygote. The zygote produces a motile form that leaves the tick’s intestine to enter its egg cells, where it multiplies and develops into motile spores. If a female tick in the next generation, i.e. one hatched from an egg containing motile spores, bites a dog, the motile spores move into its salivary glands. Each motile spore becomes very large, and is then called a sporoblast. Inside the sporoblast, thousands of sporozoites form and infest the dog. Each sporozoite enters a red blood cell and becomes a trophozoite to complete the cycle.

Babesiosis is especially common in hot and temperate climates, in the areas where ticks are abundant. It is more widespread during seasons in which ticks are active, and with certain lifestyles, such as hunting dogs. Highly-selected breeds such as Cocker Spaniels, Spaniels, Yorkshire Terriers and Dobermanns are more susceptible than others. Puppies are more vulnerable than adults.

The incubation period usually last two days to three weeks and sometimes only 24 hours. After this phase, the parasites reach the peripheral blood stream and the symptoms appear almost simultaneously. In the acute form of this disease, the dog has a very high fever and is exhausted. The fever lasts an average of 6 to 10 days. At the same time, anaemia (pallor of the mucosa) is present due to the destruction of red blood cells as the parasites multiply within them. After several days of illness, haemoglobinuria occurs: the dog passes pink to dark brown coloured urine. Atypical clinical symptoms including neurological, respiratory, gastrointestinal, cutaneous or visual signs may also appear. The course of the disease is short: one week at the most. The dog’s condition deteriorates if left untreated and it falls into a coma leading to death. A chronic form of the disease, mainly found in adults, may follow an acute form.

© Grossemy

In the chronic form of babesiosis, the fever is not as high, or is absent, and the dog’s overall condition remains good. However, anaemia is always present. This is a slow form of babesiosis, but complications may still occur. The disease may last several weeks and end with the dog’s death.

The diagnosis is based on the presence of fever and anaemia. The dog’s lifestyle should also be taken into account. Microscopic examination of the blood can confirm the diagnosis. A blood sample is taken from a peripheral area—usually the ear— and examined for the presence of Babesia in the red blood cells. The parasites are more difficult to find in the chronic forms of the disease, since there are fewer in the blood.

Specific treatments, known as piroplasmicides, are available for Babesiosis. The most commonly used is imidocarb. Sometimes two injections at an interval of 48 hours are necessary, since there is a risk of relapse. In addition to this specific treatment, symptomatic treatment should be provided, in particular correction of the anaemia (using anti-anaemic agents, or blood transfusions in the most serious cases).

Prevention is still the best cure. The disease can be prevented by destroying all ticks as early as possible, and by using acaricidal (anti-tick) treatments.

In some countries a vaccine is available against babesiosis, but it is effective for a maximum of only six months and is only about 70% effective. The vaccination protocol is as follows: two injections, one month apart, followed by a booster every 6 months to a year as a function of the risk. The dog must be in good health.

© Diffomédia/Royal_Canin

Leishmaniasis

Systemic leishmaniasis in the dog is a disease caused by a Protozoan parasite known as Leishmania (more precisely Leishmania infantum). This parasite is localised in the dog’s macrophages (white blood cells responsible for removing debris and bacteria from cells) and requires, over the course of its lifecycle, passage through a vector host which transmits the parasite from one dog to another; this vector is a phlebotomus fly (sand fly, an insect similar to the mosquito). The disease is prevalent around the Mediterranean basin and is also seen in Asia and America. In France and other Mediterranean countries, cases are localised in the South of the country, but there is a current trend towards progression to the North.

Symptoms:

following an incubation period of 3 to 18 months or more, the disease produces a collection of highly varied symptoms which when present together are indicative of the disease. There is also a general deterioration in the health status (depression, weight loss, occasionally fever, enlarged lymph nodes, etc.), skin problems with desquamation, non-pruritic hair loss, hyperkeratosis notably of the nose with ulceration, ocular disturbances with corneal lesions (keratitis and ulcers) and sometimes visceral (diarrhoea, uraemia) or joint problems (lameness). The progression of the disease is generally slow, over several months or even years, with progressive deterioration resulting in death in the majority of cases if no treatment is implemented.

Diagnosis:

 this relies on the finding of Leishmania in the macrophages (microscopic examination or using molecular biology) and via serological tests to assess the dog’s immune response against the parasite.

Treatment:

this is difficult and usually life-long. It is primarily based on the combination of meglumine antimoniate and allopurinol.

Prevention:

effective use of insecticides (pyrethroids) preventing bites from sand flies throughout the period of activity of these insects, which is usually from April to November. It is important when travelling to Southern Europe with your dog to start preventative treatment 8 days prior to departure. Sand flies are particularly active at night; it is therefore preferable to keep dogs inside from dusk onwards in affected regions.

Heart worm

This disease is caused by a filaria, Dirofilaria immitis. This worm infests the right ventricle and atrium of the dog’s heart and its pulmonary artery; it is transmitted by mosquitoes and is encountered in tropical countries and those with a hot climate such as Southern Europe and the USA.

© Diffomédia/Royal_Canin

Symptoms:

this parasitic disease results in coughing and exercise intolerance; with heavy parasite burdens the symptoms progressively worsen with weight loss and finally death due to right heart failure.

Diagnosis:

several techniques are used: cardiac ultrasonography to visualise the adult parasites and the lesions that they cause; microscopic examination of a drop of blood to observe the larvae (or microfilaria); serological testing for an antigen secreted by the female Dirofilaria immitis which means an approximate quantification of the parasite burden can be assessed.

Treatment:

this is difficult and unreliable as the destruction of the parasites results in pulmonary emboli which may prove fatal. Prevention is therefore preferable for dogs living in endemic regions or travelling to these zones, such as Southern Europe.

Prevention:

monthly administration of a macrocyclic lactone-based anthelmintic during the mosquitoes’ activity period (April to October).

© Callaloo Canis/Fotolia
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Attribute Type Value
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Parasitic infestations
    Parasitic infestations

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