Veterinary webinar by IAN WRIGHT BVM&S MSc MRCVS, Reviewed by David Grant
Ian Wright introduced this veterinary webinar, sponsored by MSD, the manufacturers of Bravecto, by stating the aim was to concentrate on where the various parasites are geographically, and to outline the threats that they pose, along with some general comments on diagnosis, control and treatment. In any parasite control programme it is important to take into consideration the risk of disease to pets, the zoonotic risk, and the risk of exposure. The geographical range of the parasite and how likely it is an individual pet will come into contact with the parasite must also be considered.
This webinar discusses:
- Fleas and Ticks
Lungworms –particularly Angiostrongylus vasorum
Ctenocephalides felis is overwhelmingly the most common flea found on dogs and cats. Occasional species include the rabbit flea, the dog flea (but virtually eliminated by the success of the cat flea,) and the human flea Pulex irritans, which is really a parasite of wildlife but will also live on humans.
Some examples of these were shown demonstrating simple anatomical differences enabling their differentiation.
Ctenocephalides felis is highly prevalent across the entire UK. It parasitises dogs, cats, rodents, lagomorphs, ferrets and wild life ‘casualties ‘ brought into the house-notably hedgehogs.
Infestation is from the environment and its success can be attributed to its rapid reproduction, a persistent environmental stage (pupae) and the wild range of potential hosts.
40-50 eggs are laid per day and these hatch in 1-6 days. The larvae pupate and emerge in 3 weeks or up to a year, (and even 2 years is considered possible), depending on the presence of a host.
Veterinary Significance of Fleas
- Flea Allergic Dermatitis (FAD)
- Human irritation
They are also vectors of disease.
Diagnosis of fleas
The use of the flea comb was emphasised and owners should be shown how to use this correctly. Owners will occasionally bring in small (just a few mm long) flea larvae and will often have suffered bites from the adults.
When should flea treatment occur?
Answer: Always, all the time, all year round. . Failing this the owner should be encouraged to check frequently with a flea comb. Generally speaking finding fleas indicates 3 to 4 months of treatment to eliminate them.
Treatment of Fleas
This is a four-stage process:
- Growth Regulator and inhibitor
- Environmental insecticide-reduces bites on human more quickly
- Cleaning of the environment
There are are over a dozen active adulticides. They are in the form of spot-ons, tablets, and collars.
A list of current products can be on the ESCCAP UK and Ireland website www.esccapuk.org.uk
Considerations when choosing an adulticide
- 100% flea control needed
- Systemic or coat distribution
- Host species to be treated (licensed product exists?)
- Duration of action
- Does it control other parasites?
- Compliance-which type of product will work best for an individual client?
- Is the host flea allergic? If so select a product with rapid kill
Pyrethroids have an important role in ectoparasites control but not as an effective flea adulticide. It is affected by heat and light and represents a risk to cats due to toxicity. Mention was made of a new daily release collar with a good safety record
Resistance to insecticides?
- There are no proven cases of insecticidal resistance in the field. One possible case has been documented in Florida but not 100% proven. Apparent resistance to insecticides can be attributed to: –
- Lack of owner compliance due to inappropriate application, frequency of application (often by conserving the product on economic grounds) and failure to treat all the animals in the house.
In the vast majority of cases ‘resistance’ can be attributed to one or more of the factors listed above.
- Growth regulators such as lufenuron, and juvenile hormone analogues such as pyriproxyfen and methoprene.
- Pyrethroids either applied by the council or by the owner as a spray
- Silicone spray entraps the pupae and is more useful where there are concerns re toxicity to fish, reptiles, and young children
- Vacuuming of carpets and
- Washing of bedding will contribute to removal of the pupae
A list of products is to be found on the ESCCAP UK and Ireland website as previously mentioned.
Ferrets and Rabbits
Imidocloprid / Moxidectin and Fipronil are licensed for ferrets. Imidacloprid is licensed for rabbits
In the UK tick species can be divided into endemic species and ‘visitors’
Ixodes species comprise 99%, but there are endemic pockets of Dermacentor in small areas of Wales, and the south of England
- Present everywhere in the UK
- Focal distribution in high prevalence areas. These include the west country, south east England, the highlands of Scotland and the Lake district
Ixodid ticks are hard ticks with ventral plates, and are inornate (not exactly beautiful to look at). Males are very small 2-7 mm long and the females are much larger when engorged. Visitors are frequently ornate-they have coloured scutum for example and if seen report them to the nearest veterinary school.
There are 3 predominant ticks in the UK
- Ixodes ricinus seen predominantly on moorland and rough pasture
- Ixodes canisuga the dog tick. May be seen in dens in rural areas or in kennels
- Ixodes hexagonus –the hedgehog tick.
All are potential vectors of Lyme disease
What is the veterinary significance of ticks?
They are ugly as far as the owner is concerned and early presentation to the veterinary clinic is the norm. They may induce pyaemia or dermatitis. Anaemia is a possibility and they are vectors of disease
Lyme disease is primarily a problem of dogs and man, cats being resistant to infection. The cause is Borrelia burgdorferi, a spirochete bacterium.
- Polyarthritis/degenerative joint disease
- Fever, depression, anorexia
- Renal and cardiac complications in severe cases
- Erythema migrans ‘Bulls Eye’ lesions in humans-not seen in the dog.
Diagnosis of Lyme Disease
- History of tick exposure, particularly in Lyme disease endemic areas
- Demonstration of parasite in blood smears or joint tap
- Antibody detection (indicates exposure not necessarily active infection)
- More expensive but excellent sensitivity and specificity
- Doxycycline 10mg/kg for a minimum of 4 weeks is the treatment of choice. The drug is passed in faeces so does not affect kidney function
- Other tetracyclines are also effective
- Assess renal function if these are used
- Supportive treatment
- Wildlife and tick reservoir makes elimination of the parasite impractical
- Control is centred around preventing exposure
- Avoid known endemic areas although potentially this includes most of the UK
- Chemical prophylaxis is the mainstay of prevention
- Removal of ticks within 24 hours of attachment and before transmission of infection is important too