External Parasites

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

Fleas Most common external parasite of cat and dog Small, wingless insect Adults: reddish brown, hard shells Lay 15-20 eggs a day; eggs hatch in fall Flourishes in warm, humid environments of 65-80 degrees Not host specific and will attack any animal for a blood meal Intermediate host for the tapeworm Transmits several diseases including Bubonic plague

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

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 9-200 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

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

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

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)

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

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

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

Mange (Severe Case)

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

Ear Mites

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

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

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

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

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

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

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