1. External Parasites

2. External Parasites Several invade all types of small and large animals
They live in hair coat, on skin, or within ear canals
Fleas
Ticks
Lice
Mosquitoes
Biting flies
Mites
Ringworm

3. Fleas Most common external parasite of cat and dog
Small, wingless insect
Adults: reddish brown, hard shells
Lay eggs a day; eggs hatch in fall
Flourishes in warm, humid environments of degrees
Not host specific and will attack any animal for a blood meal
Intermediate host for the tapeworm
Transmits several diseases including Bubonic plague

4. Flea - Types Ctenocephalides canis Ctenocephalides felis
Both species of flea will attack dogs and cats

5. Flea – Life Cycle
Can be as short as 16 days or as long as 2 years depending on environmental conditions
Female will take a blood meal from host and begin to lay eggs
Eggs are not sticky and fall off host
Depending on conditions, eggs take 2-12 days to hatch
Larvae grow and molt over days as they feed on organic matter called “flea dirt” from adult fleas
“Flea dirt” falls off host with eggs
Larvae spin a cocoon and pupate for 7 days to a year depending on conditions
Adult emerges, cycle begins again
Adult fleas can survive several months without feeding

6. Flea – Clinical Signs
Flea allergy dermatitis – severe skin irritation and itching in some animals due to allergic reaction caused by flea saliva
Itching, scratching, biting at skin, hair loss, scabs, bumps
Anemia – loss of blood
Bartonella – bacteria spread by fleas; common in cats
Hemobartonella or Feline Infectious Anemia – caused by flea bite with bacteria, infects animal’s RBCs and immune system

7. Fleas - Diagnosis
Easiest way to check for fleas is to place a white piece of paper under the animal’s belly
Rub belly
“flea dirt” will fall from the coat onto the paper
Add water to “flea dirt”
It will turn a reddish
brown indicating fleas

8. Lice Louse is a small wingless insect Stick to hair coat
Very host specific
Some species of lice will infest dogs and cats year round
Livestock animals such as horses and cattle are generally infested during the winter
Two types:
Mallophaga (chewing)
Anoplura (sucking)

9. Lice – Life Cycle 3 – 5 weeks Must live on its host at all times
Adult louse lays an egg called a nit
Nit is sticky so it attaches to coat
Nit develops into immature stage of the adult called a nymph and then into an adult

10. Lice – Clinical Signs and Treatment
Adult lice are visible to the naked eye
Louse cause intense itching and may cause hair loss
Treatment is available

11. Mites Microscopic parasites Host specific
Can only infect other animals by direct contact
An animal that has a mite infestation is said to have “mange”
Live on skin and hair coat
Many forms and invade several areas

12. Mange (Severe Case)

13. Mites - Types Ear Mites (Otodectes)
Sarcoptic Mange (Sarcoptes) – caused by infection with the Sarcoptes scabei mite
Causes condition known as scabies in humans
Highly contagious by direct contact
Demodectic Mange (Demodex) – another mite that invades the skin and all dogs raised normally by their mothers possess this mite

14. Ear Mites

15. Mite – Life Cycle Each species of mite has a different life cycle
Length of life cycle is anywhere from 17 – 35 days depending on the species
All species go through the egg, larva, nymph, and adult stage
Some species of mite burrow into the skin while others live in the ear canal or in hair follicles

16. Mite – Clinical Signs & Diagnosis
Intense itching, oozing of skin, scaly patches without hair on head and neck area and around elbows
Ear mites will cause animal to scratch at its ears and shake its head in irritation
Diagnosis:
Skin scraping
A fold of skin is pinched and scraped with a scalpel until area oozes with blood
Scraping is placed on a microscope slide with a drop of mineral oil and scanned for mites
For ear mites, a swabbing of the ear canal is placed on a slide with mineral oil and examined

17. Ticks Blood-sucking arthropods Seek heat and movement
Not host specific, although they do have a host preference
Located throughout US in grassy and wooded areas
Vectors for Borrelia burgdorferi, the organism that causes Lyme disease
Common species: American Dog Tick, Deer Tick, Brown Dog Tick, Lone Star Tick, the lxodes species

18. Ticks - Types Ixodidae – hard ticks Argasidae – soft ticks
American Dog Tick – transmits disease known as Rocky Mountain Spotted Fever
Signs: fever, joint pain, depression, anorexia
Deer Tick – transmits a common disease called Lyme disease
Causes joint pain, lameness, fever, depression, anorexia, lethargy, swelling of joints
Babesia – another disease spread by ticks
Signs: anemia, jaundice, fever, vomiting

19. Mosquitoes Very small flying insects Survive on blood
Capable of spreading diseases from animal to animal
West Nile Virus – mosquito-borne disease that causes inflammation or swelling of the brain and spinal cord
Also carry heartworm microfilaria

20. Biting Flies Can cause lots of irritation
Equine Infectious Anemia – viral disease; no vaccine and no cure
Coggins Test – screens for EIA virus
Prevention: use of fly sprays and manure,
waste control and waste removal
are helpful

21. Ringworm Dermatophytosis Fungus on skin
Hair loss, with itching in large patches
Circular skin lesions
Contagious to humans and other animals