L13 & 14 small animal ectoparasites

Fleas Introduction/Importance

Spread all over the world

The most important ecto-parasites of dogs and cats;

Intermediate host for Dipylidium caninum, Acanthocheilonema reconditum;

Can transmit bacteria

Ctenocephalides felis

Fleas Significance for humans

Ctenocephalides spp. can bite humans, especially when:

• Pets are temporarily removed;

• Flea populations are large.

Ctenocephalides spp.

Morphology

Ctenidia

Up to 2.5 mm long, brown/black, flattened laterally;

Body made up of head, thorax and abdomen;

Genal (7-8 spines) and pronotal (16 spines) ctenidia (combs)

Eyes present;

Legs: developed, 3rd pair most developed.

Morphology: Ctenocephalides felis vs C. canis

Head of female Ctenocephalides canis and Ctenocephalides felis

Ctenocephalides spp. Feeding

• The adult fleas feed on blood (piercing-sucking mouth parts);

Once on a host fleas start feeding within minutes

Fleas ingest more blood than they need => nutrition for larvae

• 220 females might consume 10% of an 0.45 kg kitten’s blood/day => anemia;

Larvae feed on adult fleas faeces, each other (cannibalism) and egg shells (chewing mouthparts).

Ctenocephalides spp.: Feeding image

Ctenocephalides spp. Life cycle

Adults: permanent ectoparasites;

Eggs: laid on the host but fall in the

environment;

Larvae: develop in the environment;

Pupae: develop in the environment;

Pre-emerged adults: environment

Host environment

• Bedding and carpeting

• Backyard

• Garage, porch, under the house

• Parks

Ctenocephalides spp.: Adult stage

• Permanent parasites, less than 15 % would leave the host => the usual way of acquiring fleas: from the environment

• Grooming is very important in parasite-host relationship

Ctenocephalides spp.: Eggs

Females begin laying eggs 24 to 36 hours after first blood meal

Most eggs fall off the host within 8 h  they accumulate where pets sleep and rest;

• Favourable conditions for development: relative humidity >50%, temperature around 25° C;

Ctenocephalides spp: Larvae

• Most larvae develop at the base of carpet: inaccessible to many insecticides;

Ctenocephalides spp: Pupae

• L3 spins a silk like cocoon in which it turns into a pupa (time to build 5 - 14 days);

• Best protected and resistant life stage;

Ctenocephalides spp.: Pre-emerged adults

• The “waiting stage”, ideal for survival during the absence of hosts;

• Emergence after 10 days or 6 months (known as “the pupal window”)  problems in control;

• Factors responsible for adult emergence: host stimuli:

- pressure, heat, light, air currents

Ctenocephalides spp. Epidemiology

About 5% of the flea population live and feed on the animals, the rest (eggs, larvae & pupae) is in the environment;

Ctenocephalides spp. can feed on many host species

• The houses offer conditions for the life cycle to be completed all year around;

Pre-emerged adults can survive long time within the cocoon (up to 6 months): ‘pupal window’;

• Infestation usually is carried out with fleas from the environment

• Sites of infestation: home, garage, yard, under house, parks etc;

The flea populations and the prevalence of infestations with fleas depend on the season => higher prevalence during the spring and summer;

Ctenocephalides spp. Effect on the host 1

1) Irritation• Physical presence of the fleas and their movement;

• Action of sucking blood (the flea bite is seen as a red spot with a halo varying in width and elevation).

• Injection of saliva

Ctenocephalides spp. Effect on the host 2

2) Anemia from blood loss

In non-allergic dogs clinical signs and skin lesions are minimal

- Pruritus, scratching, alopecia, chewing, have tapeworms etc

Ctenocephalides spp. Effect on the host 3

3) Flea allergy dermatitis (FAD)

• Most, if not all dogs, become allergic to salivary antigens of fleas;

Type I (immediate, IgE mediated => mast cell degranulation);

Type IV (delayed, cell mediated – T-DTH)

Cutaneous basophil hypersensitivity

Ctenocephalides spp pathogenesis depends on

• Genetic predisposition to develop allergic diseases (dogs with other allergic diseases are at high risk);

• The numbers of fleas feeding and amount of antigen injected (one flea enough?);

• Frequency of flea exposure – intermittent exposure favours the development of the FAD while continuous exposure favours immune tolerance;

• The age at which first exposure occurs - early exposure probably protects against the development of FAD;

• Presence of secondary or other concurrent skin disease;

• Effects of previous or current treatments;

Ctenocephalides spp. Clinical signs of FAD 1

FAD can occur in dogs of any age but the most common age of onset is 2 to 5 years (occasionally it may

be seen in very old dogs and cats or those as young as 6 months);

No sex or breed predisposition;

In temperate climates FAD is typically worse in

the summer and fall (in warm climates the problem may be non- seasonal);

• The dermatitis is typically confined to the dorsal lumbosacral area, forming a typical triangular shape;

Ctenocephalides spp. Clinical signs of FAD 2

Small pruritic, erythematous wheal can be seen at the flea bite site;

Develops into a pruritic papule that might be short lived being

disturbed by self-trauma;

Pruritus and repeated self trauma, chewing, licking => diffuse erythema, excoriations, alopecia, stubbed or broken hairs, crusts etc;

The dogs try to bite or chew at the areas where fleas are/bite  seem to hunt the fleas down in their hair coat (nibbling/corncob biting);

Ctenocephalides spp.

Clinical signs of FAD in dogs

• Pyotraumatic dermatitis

Ctenocephalides spp.

Clinical signs of FAD in dogs

In time, lichenification and hyperpigmentation, crusts and scales develop;

Ctenocephalides spp.

Clinical signs of FAD in dogs

• Fibropruritic nodules

• Secondary infections;

Ctenocephalides spp. Clinical signs of FAD in cats

FAD is seen in cats of any age, sex and breed;

The most common cause of ‘feline miliary dermatitis’;

The primary clinical lesion seen in the cat is an erythematous papule covered by a small reddish-brown crust (miliary dermatitis type lesion);

• These pruritic lesions are usually most severe on the head, neck, and dorsal lumbosacral regions but have a tendency to generalize;

Ctenocephalides spp.

Clinical signs of FAD in cats

PRUITUS

moderate to severe pruritus => licking, scratching, chewing, and violently attacking areas of the skin without visible provocation;

Scaling, broken hairs, restlessness, weight loss etc;

Ctenocephalides spp.

Clinical signs of FAD in cats

• Alopecia

highly variable

Ctenocephalides spp. Diagnosis

1. Clinical signs and history (timing, presence of in-contact animals, lack of preventive treatments, owners bitten by fleas etc);

2. Response to insecticidal (corticosteroids?) treatment;3. Visualization of fleas or flea faeces on the body of the host;

The use of a fine-toothed metal comb can help:

• Pick fleas out of the coat (combing after applying an insecticide);

• Flea faeces: reddish-brown particles that will dissolve in water or alcohol to form reddish stains;

Visualization of Dipylidium caninum proglottids

(faeces, bedding, body of the host)

Physical examination

Dogs: examine the dorsal lumbar area for papules, which are the primary lesions seen in canine FAD;

Cats:carefullypalpatetheskinincats(thesmall,crusted papules (miliary crusts/dermatitis) often are more easily felt than seen;

7. Allergy testing

Intradermal testing•

In vivo test used to demonstrate immediate (20 min) and delayed (48

hrs) hypersensitivity reactions;

ELISA: • Detect specific IgE

Ctenocephalides spp.: DD

sarcoptic mange

Sarcoptic mange

History (exposure to infested dogs – boarding kennels, grooming facilities, played with other dogs etc);

Highly contagious;

Lesions usually starts on the head/ears;

Intense pruritus;

Deep skin scrapings (ear margins) needed to visualize the mites;

Humans (owners): might be affected  intense itching;

Response to treatment

Results of serological tests (ELISA) and pinnal-pedal reflex;

Ctenocephalides spp.: DD

demodicosis

History (mother & siblings suffered from demodicosis);

Not contagious and humans not affected;

Not very itchy before bacterial complications occur;

Distribution of the lesions (commonly head affected initially), features of the lesions (well defined in localized demodicosis);

• Positive skin scrapings;

Ctenocephalides spp.: Differential diagnosis in cats

1) Integrated Flea Control

• Kill the (adult) fleas on the dog/cat

- High initial speed of kill of the product => quick relieve of the pet discomfort;

- High residual speed of kill of the product => resolve FAD and control the flea infestations

• Eliminate the immature stages from environment

• Insect growth regulators (IGRs) => break the life cycle;

• Treat the indoor/outdoor environment;

Education of the pet owner.

Mechanical control measures;

a) Commonly used adulticides

Phenylpyrazoles: Fipronil

Bispyrazoles: Tigolaner

Neonicotinoids: Imidacloprid

Oxadiazines: Indoxacarb

Pyrethrins/Pyrethroids: Permethrin (NOT FOR CATS), Flumethrin

Isoxazolines: Esafoxolaner (Cats), Sarolaner (Cats), Fluralaner

Macrocyclic lactones (MLs): Selamectin

Neonicotinoids: Nitenpyram

Spinosyns: Spinosad

Isoxazolines: Afoxolaner (Dogs), Sarolaner (Dogs), Fluralaner (Dogs), Lotilaner

Isoxazolines: Fluralaner

b) Insect Growth Disruptors/Regulators (IGDs/IGRs)

Interfere with growth and development of immature stages of the insects;

Eliminate the environmental stages => prevent re- infestations;

Generally they have no effect on adults => lag between the initiation of treatments and reduction in the number of adult fleas on the host;

Commonly combined with adulticides;

Juvenile hormone analogues (JHAs):• Methoprene (spot-on), pyriproxyfen

Insect development inhibitors (Chitin synthesisinhibitors (CSIs): Pupa

Cocoon

• Lufenuron

c) Mechanical means of environmental control

• Vacuum of carpets, rugs will remove many of the eggs (59%), faeces and larvae (up to 27%);

• Wash the pet bedding or bed cloths with boiled water;

• Treat the indoor and outdoor environment with

insecticides

Failure of control measures

Chemoresistance?

Proven to carbamates, organophosphates and pyrethroids;

Fipronil?

Ask the owner if the products were applied correctly (on the skin and not on the haircoat for the topical drugs), observing the timing etc;

Ask the owner if she/he treated all the pets in the household;

Is the pet's environment shared with wildlife or unknown animals?

2) Provide the animals with relief from pruritus/allergic reactions

3) Treat any secondary infections

Pediculosis

Infestation with lice in small animals

• Trichodectes canis

• Heterodoxus spiniger

• Linognathus setosus

Lice in dogs: Trichodectes canis

Head, wider than the thorax and of rectangular shape (broader than long); antennae are visible;

Legs (3 pairs) are stout, end in single claws;

The abdomen is wide (almost circular in female) and has many rows of large, thick setae; Feed on epidermal debris and blood

Life cycle: eggs are glued at the base of the hairs => nymphs hatch in 1-2 weeks => moult 3 times => adults (30 days);

Lice in dogs: Heterodoxus spiniger

Morphology

Yellowish, about 3 mm long;

Head:

Triangular, rounded forehead;

Provided with is a pair of strong, ventral, spine-like

processes;

Antennae not visible;

Legs: provided with 2 claws;

Feeding: seems to prefer blood.

Heterodoxus spiniger (Kangaroo louse)

Lice in dogs: Linognathus setosus

Head

Narrower than the thorax;

Legs: first pair smaller than the 2nd and 3rd pairs,

Feeding: blood;

Lice in dogs

Epidemiology

Host specific;

All developmental stages are present on the host (unlike fleas and ticks);

Less common than in the past

More common during the cold season

Common in young animals and immunosuppressed or neglected /debilitated animals =>massive populations can develop rapidly in these animals

Transmitted mainly by direct contact => infestations are common where animals are housed together;

Lice in dogs

Pathogenesis

Pathogenesis

Location: generally on the head, neck, ears, back and trunk;

Some individuals may suffer less and others may suffer from severe dermatitis

Huge populations may develop rapidly on neglected, poorly nourished, newborn puppies;

Chewing lice are more active and tend to be more irritant than sucking lice => itching => scratching => alopecia, excoriations, scaling, bacterial complications etc;

Sucking lice cause anemia and debilitation;

Lice in dogs

Clinical signs

Pruritus => alopecia => restlessness;

Thickly matted hairs;

Small papules and crusts;

In severe infestations: anemia, weakness, debilitation;

Lice in dogs

Diagnosis

History

Clinical signs (pruritus, scratching, alopecia etc);

Visualisation/identification of the lice or eggs

Adhesive tape

Differential diagnosis

Lice in dogs

Treatment

Generally, drugs used for the treatment of flea infestations work well against lice;

Treat all in contact animals;

Clean and treat the bedding, grooming supplies etc.

- Pyrethrin, pyrethroids

- Fipronil

- Imidacloprid

- Selamectin

- Isoxazolines: seem to be highly effective

Lice in Cats: Felicola subrostrata(us)

Felicola subrostrata(us)

Shape of the head is triangular, pointed anteriourly;

Median longitudinal groove on the head;

Life cycle

Eggs are glued by the female lice to the hair shafts =>3

nymphal stages => adults;

Life cycle can be completed in 30-40 days;

Feed on skin debris and probably skin exudates.

Felicola subrostrata: Epidemiology and Clinical signs

Transmitted mainly by direct contact (grooming supplies);

Common in animals kept in poor conditions, older, long-haired cats that are unable to clean themselves;

Areas most commonly affected: head, face, pinnae, neck, back, tail;

Scaling and lice (Gauguere, 1999).

Irritate the host => pruritus & restlessness => scratching => alopecia, skin lesions;

Scaling, dull coat, papule, crusts;

The hair coat may be matted and have a ruffled appearance, due in part to the accumulation of skin exudates in the hair;

Anorexia, debilitation;

Felicola subrostrata: Diagnosis

Clinical signs;

Finding lice and/or eggs on the body of the cats

Felicola subrostrata: Treatment

Fipronil

Imidacloprid

Selamectin

Treat all cats in the household;

Clean and treat the bedding and the grooming supplies.