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Advocate®: Effective Against Fleas

Fleas are recognized as a major cause of skin disease for dogs and cats. However they also act as the intermediate host for the tapeworm Dipylidium caninum, and are a zoonotic parasite as well. Studies demonstrate that the moxidectin / imidacloprid combination of Advocate® deliver the same high level of flea control expected from Advantage®.

The Parasite

Fleas are the most prevalent ectoparasites of companion animals worldwide. The cat flea (Ctenocephalides felis felis, Bouché 1835) will feed on a wide variety of animals including cats and dogs, although it is not equally well adapted to all hosts. Fleas threaten the health of humans and animals due to bite reactions and transmission of diseases.

The fact that fleas are major nuisance pests, a matter of public health, and a major cause of disease makes flea control a definite necessity. The annual expenditures by pet owners for flea control products remains on a high level and this figure increases from year to year. Furthermore, flea-related diseases account for over 50% of the dermatological cases reported to veterinarians and 35% of their overall practice services.

Diseases caused or mediated by fleas include:

  • Flea bite dermatitis
  • Flea bite hypersensitivity or flea allergy dermatitis (FAD)
  • Transfer of Dipylidium caninum
  • Transfer of Bartonella henselae, a zoonotic bacterium1
  • Transfer of Mycoplasma haemofelis2

Life Cycle

The flea is dark brown in color, wingless and possesses a laterally compressed chitineous abdomen. The glossy surface of the body allows easy movement through hair and feathers. Compound eyes are absent, but some species have large or small simple eyes. The legs are long, strong and adapted to leaping. This is especially evident in the third pair of legs, which are much longer than the others and muscular.

The flea develops through a number of stages, beginning with the egg, followed by the larva, pupa and, finally, the adult stage. The life cycle of the flea is one of complete metamorphosis. It can be completed in as little as 14 days or be prolonged up to 140 days, depending primarily on environmental temperature and humidity. The life cycle of most flea species is characterised by three events: the hatching of the egg (incubation), the period from 1st instar to pupa, and the period from pupa to adult.

Fig.1: Life Cycle of the Cat Flea

To watch or download the animation of this life cycle please visit our download area.

Concerning pets, particularly cats and dogs, only a restricted number of flea species occur in large numbers with enough regularity to be considered important nuisance pests.

In the United States these are: Ctenocephalides felis felis, the cat flea; Ctenocephalides canis, the dog flea; Pulex irritans, the human flea; and Echidnophaga gallinacea and Ceratophyllus gallinae, fleas found on poultry.

A similar situation exists in Europe and other parts of the world, with C. felis felis and C. canis mainly dominating. P. irritans and Archaeopsylla erinacei, the flea of the hedgehog, are also other species with high possible rates of infestation.

Pathogenesis and Clinical Appearance

Flea allergy dermatitis (FAD) is one of the most frequent causes of skin conditions in small animals and a major clinical entity in dogs.

The hypersensitivity to flea bites is not only seen in dogs, but is also a major cause of feline miliary dermatitis and other pruritic skin diseases in cats. Furthermore, fleas as hematophagous insects can also cause an imbalance in the circular system. Flea infestation is not only important for dogs and cats as the definitive hosts, but also for humans, especially children.

Fig. 2: Clinical signs of FAD in a cat infested with cat fleas (C. felis)

The clinical signs of flea allergy in the dog and cat are the result of pruritus and self trauma. They can be quite variable, depending on the degree of sensitivity, the level of flea exposure, the stage of the disease (acute versus chronic) and the presence of concurrent primary (atopy) or secondary (bacterial folliculitis) skin disease.

The classic primary skin lesion in the hypersensitive dog or cat is a small pruritic, erythematous wheal (immediate hypersensitivity) noted at the site of the flea bite. The dermatitis in the dog is typically confined to the dorsal lumbosacral area, forming a typical triangular image or an inverted V pattern, also sometimes affecting the caudomedial thighs, ventral abdomen and flank. Other commonly involved areas are the neck, the cranial aspects of the forearm, and the base of the ears.

With prolonged exposure to fleas, the acute primary lesions are rapidly replaced by chronic secondary lesions that result from pruritus and repeated self trauma. Diffuse erythema, excoriations, and partial to complete alopecia replace the initial wheal or papule. Secondary seborrhea with odor (like rancid butter) is common. Long-standing pruritus and self-trauma may lead to the marked secondary changes of acanthosis, hyperkeratosis, lichenification, and hyperpigmentation.

Zoonotic significance

The flea as a source of medical problem has been recognized since historic times. The Oriental rat flea (Xenopsylla cheopis) was the major transmitter of Yersinia pestis - the bacteria that causes the bubonic plague, or „black death“, in humans. Furthermore, a variety of bacteria and viruses have been reported to be transmitted by the cat flea (C. felis), as well as the dog flea (C. canis). The cat scratch fever caused by the gram negative bacteria Bartonella henselae is a well-described zoonotic disease with a high incidence, especially among cat owners. Recent research has shown that flea faeces are the major way that the disease is spread between cats and from cats to humans.


Flea infestation in fur bearing animals is not always visible to dog or cat owners. This is even more so in pets with low flea burdens. The use of a fine-toothed comb, called a flea comb, can be used to pick up fleas out of the coat or aid in harvesting particles of flea excreta. Additionally, visualisation of debris left on the examination table with a handheld magnifying lens may reveal the ovoid white eggs of fleas as well as flea faeces.

Efficacy of Advocate®

Imidacloprid is already well-known for its efficacy against fleas, and its presence in Advantage and advantix means that both of these products are very effective in the treatment and control of flea infestations.

Table 1: Efficacy of Advocate® (percentage flea reduction) against adult fleas (C. felis)3,4
  Day 1  Day 7  Day 14  Day 21  Day 28  Day 35 
Canine Advocate®  99.8  100  99.5  99.1  97.7  95.1 
Feline Advocate®  100  98.9  98.9  97.3  97.9  89.8 

As can be seen from these studies, Advocate achieved > 97% efficacy from day 1 to day 28 in these two studies (Table 1).

Another study compared the efficacy of Advocate with that of Advantage on dogs.5

This study demonstrates that the moxidectin / imidacloprid combination delivers the same high level of flea control expected from Advantage (Table 2).

Table 2: Efficacy of Advocate® and Advantage® (percentage flea reduction)5
 Day 1 Day 7 Day 14 Day 21 Day 28 Day 35 
Advocate® 99.5 99.9 100 99.7 99.9 99.7 
Advantage® 99.5 100 100 100 99.6 99.0 

Imidacloprid also exerts a larvicidal effect in the surroundings of a treated pet. Following contact with a treated animal, it kills larval stages in the pet’s immediate surroundings.

Furthermore, due to the high level of flea control provided by Advocate, it is also licensed as part of a treatment strategy for flea allergy dermatitis.

Copyright © Bayer HealthCare AG