Ectoparasites of Pets

Ticks and Fleas are the most common and most important ectoparasites of companion animals throughout the world. Next to these are mites, lice, sand flies and mosquitoes as nuisance ectoparasites. Here’s more on fleas and ticks on dogs and cats.
 
Fleas on dogs and cats
These small dark brown insects prefer temperatures of 20–30 degree Celsius and humidity levels of 75-85%… so for some areas of the country they are more than just a ‘summer’ problem. Dogs and cats often get infested with fleas through contact with other animals or contact with fleas in the environment. The strong back legs of this insect enable it to jump from host to host or from the environment onto the host. (Fleas do not have wings so cannot fly!)
The flea’s bite can cause itching for the host but for a sensitive or flea-allergic animal, this itching can be quite severe and leads to hair-loss, inflammation and secondary skin infections.
Commom species of fleas in cats & dogs are:

• Ctenocephalides felis, the cat flea, (A) original size 2.1 mm
• Ctenocephalides canis, the dog flea, (B) original size 3.2 mm

Understanding the flea life cycle
There are several stages to its life cycle: egg, larva or caterpillar, pupa or cocoon, and adult. The length of time it takes to complete this cycle varies depending upon the environmental conditions such as temperature, humidity, and the availability of a nourishing host. The adult female flea typically lives for several weeks on the pet. During this time period she will suck the animal’s blood two to three times a day and lay twenty to thirty eggs each day.
The egg then hatches into larvae. These tiny worm-like larvae live among the carpet fibres, in cracks of the floor, and outside in the environment. They feed on organic matter, skin scales, and even the blood-rich adult flea faeces. The larvae grow, molt twice and then form a cocoon and pupate, waiting for the right time to hatch into an adult. These pupae are very resilient and can survive for along time. Then they emerge from their cocoons when they detect heat, vibrations and exhaled carbon dioxide, all of which indicate that a host is nearby.
The newly emerged adult flea can jump onto a nearby host immediately. Under optimal conditions, the flea can complete its entire life cycle in just fourteen days.
Damage to health in pets
Flea infestation can disrupt the general well-being of all animals. The most harmful effects are:

• Flea Allergy Dermatitis in dogs
• Feline Miliary Dermatitis in cats
• Anaemia & weakness
• Transmission of tapeworm Dipylidium caninum through ingestion of fleas by dogs.
• Transmission of bacterial diseases

Ticks
The most important species of hard ticks as parasites of companion animals in India are:
Rhipicephalus sanguineus (Brown Dog Tick). The ticks can feed for extended periods of time on their hosts, varying from several days to weeks, depending on such factors as life stage, host type, and species of tick. The adult ticks can suck anywhere from 200-600 times their unfed body weight. Ticks are obligate blood feeders. All active stages require blood as a nutritive source and, in the case of adults, for sperm or egg production.
Host seeking: Hard ticks seek hosts by an interesting behaviour called ‘questing.’ Questing ticks crawl up the stems of grass or perch on
the edges of leaves on the ground in a typical posture with the front legs extended, especially in response to a host passing by.
Developmental cycle: All ticks have four stages, the embryonated egg and the three active stages, the larva, one or more nymphal stages, and the adult.
Tick borne diseases
Most prominent being Tick Fever which is a collective term used for 3 or 4 major diseases caused by ticks are:

• Ehrlichiosis caused by Ehrlichia canis
• Hepatozonnosis caused by Hepatozoon canis
• Rickettsia rickettsia
• Babesiosis caused by Babesia canis
• Blood loss leading to anaemia
• Tick paralysis

Control of Ectoparasites
When it comes to ectoparasites, prevention is the key. Attempting to control ticks and flea on our dogs and cats is a multi-step process.
To have a successful ticks and fleas control program we must:

• Remove ticks and fleas from the indoor environment.
• Remove ticks and fleas from the outdoor environment.
• Remove ticks and fleas from the pets.
• Keep future ticks and fleas away.

Choice of right drug
You must choose an ectoparasiticide on the basis of following criteria:

• Important features of a modern ectoparasiticide–Clear an existing ectoparasite infestation by demonstrating: Efficacy > 90% within 24 hour post application, which means should have fast Onset of efficacy or ‘Speed of kill.’
• Prevent re-infestation (control) for a longer period.
• Persistency /repellency.
• Safety for pet animal, pet owner and environment.
• Owner compliance – should be easy to use/apply.