MITES Flashcards
Mite on dog, Round, spines on dorsal durface, stumpy legs that extend juuuust beyond body margin, covered in scales and thumb print.
Intensely pruritic, hair loss, crusting and papular lesions
transmitted?
Diagnosis?
- SARCOPTES SCABEI
- one species, hsot adapted
- transmitted during physical contact, highly contagious
Diagnosis - Itchy dog, skin scrapings, dermatitis in household (transient)
ELISA test
Lifecycle sarcoptes scabei
- Female creates winding tunnels in keratin parallel to the skin surface, feeding on fluid between the cells
- Each tunnel (1.0-2.0cm in length and just below the skin) contains a single female mite - three eggs per day; hatch to larvae within the tunnels after 3-4 days.
- Larvae exit the tunnels and successive moulting to eight-legged protonymph, tritonymph and adults
- Egg-to-adult life = 14 days.
How to control sarcoptes scabei in dogs
• Control: Amitraz washes or Selamectin a macrocyclic lactone (same group as I but not Ivermectin contra-indicated in dogs, collies, sheep dogs and crosses – CNS signs and toxicity)
• Moxidectin/Imidacloprid combinations are also licenced to treat Sarcoptes scabiei
• Fluralaner more recently
• Treat all in contact dogs
o Even if not showing signs, could be infected
• Treat all grooming instruments and bedding
Mite found on cat face, head, ear, round, prominent dorsal striations in the form of concentric rings “thumb print, No scales and spines, Very small (200µm), dorsal anus (arrow) rather than under.
NOTOEDRES spp (cati)
• Life cycle similar to S. scabiei
• Transient human dermatitis - zoonotic
• Treatment – Selamectin
Long, cigar shaped mite found on a dog….
DEMODEX spp
• Many species, host-specific – highly evolved for living within hair follicles and sebaceous glands
• Commonly dermatological problem of dogs - Demodex canis main species
Life cycle demodex
• Demodex spp. Normally commensal
o Present on all animals, humans
o Issue when find LOADS, associated with clinical signs. 1 or 2 in a skin scrape are no concern
• The life cycle takes 18-24 days to complete.
• Demodex spp. are unable to survive away from the host’s body.
• In dogs, transmission is via the mammary skin while pups suckling
o See lesions around muzzle in young pups. Usually resolves
• Demodex spp affect all animals, humans too; very host specific.
• Disease very rare in cats
Significance of demodex mite
• When health is compromised….
o Immune compromised or other issue
• Scaling and alopecia; papules and pustules may form on the face, shoulders, neck and limbs.
• In dogs, there are two clinically distinct forms; classified in various ways.
o Localised form - seen mainly in young dogs - lesions around muzzle may spontaneously resolve.
o Generalised/sometimes pustular is a severe disease complicated by secondary bacterial infection
Aetiology complex
Can be adult or juvenile (<18 mths) in onset. Complex pathogenesis. Thickened skin, pustules, crusts
Demodex diagnosis and treatment
• deep skin scrapings as deep in hair follicle and sebaceous gland,
• Trichograms – taking hair might recover some mites
Treatment
• can be difficult
• Amitraz washes at about 5-7 day intervals;
• Imidacloprid/Moxidectin spot ons; plus Antibiotics
• Lotilaner approved 2017 (latest isoxazoline)
Mite with a pointed head and Pedicles at end of front legs, 3 segmented and end in trumpet shaped sucker, thumb print… what is it?! sheep and cattle
PSOROPTES MITES!!!!!
Psoroptes ovis/ bovis, non burrowing
SHEEP SCAB
Mite with oval shaped, round mouthparts and sucker shaped pedicle, thumb print
Choriptes bovis, non burrowing
Diagnosis of sheep scab
- clinical signs
- skin scrap from periphery lesion using scalpel – much do several lesions and several animals
- Part wool and visually see
- Can macerate ‘scabby’ material in 1-5% KOH for 5-10 mins to release mites
- View under microscope – may see life cycle stages, eggs, cuticles
- Chewing lice (Bovicola=Damalinia) and forage mites sometimes associated with scab lesions – they like the scabs produced by Psoroptes ovis
Life cycle psoroptes
What deos feed on
16 days life cycle, can be 10 days in warmer.
Eggs in fleece, hatch in 3 days, 6 leg larvae, 8 legged nymph, 8 leg nymph, adult
Non burrowing = feeds at surface of skin, lipids, superficial fluids, cells, bacteria, lymph. Any blood inside is accidental ingestion
Talk about psoroptes ovis/ bovis lesions
- Centre of lesion becomes thick and crusty – expands away from centre region – active mites on edge of lesion, expands
- Small serum filled vesicle ruptures to form moist yellow pustule ~0.5cm
- Centre will contain mite egg shells and other signs of early life stages.
- Inflammation, serous exudate, scale and crust
- Mites found in moist skin at edge of lesion – density highest here:
o Where conduct skin scrape? - Lesion extends rapidly, can cover ¾ of body in 6-8 weeks
- Can have rapid progression and death
clinical signs of psoroptes mange
- P mange results in severe irritation, scratching, hair loss, skin damage and weight loss
- Untreated can result in death from secondary causes e.g. dehydration or bacterial septicaemia
- Intense itching, rubbing, scratching, nibbling
Psoroptes mange in sheep
WHEN?
WHere are mites?
- Late autumn/ winter disease – longer fleece length
* Mites in axilla, ears, scabs, folds of skin, long fleece
Feeding habits of psoroptes and what this means when treated
- Peirce skin, feed on lymph, faeces contain antigens which promotes hypersensitivity response in animal, serum to area and mites feed on.
- One treat don’t necessarily see improvement in symptoms for a while until recovered from hypersensitivity response.
How do we treat AN EXISTING infection of psoroptes ovis?
Total immersion plunge dipping (Diazinon, an Organophosorous (OP) chemical ): 60 secs, head under X2 Injectable MLs: 1. IVERMECTIN – 2X 3 days apart 2. DORAMECTIN 3. MOXIDECTIN 1% 2 X 10 days apart or LA
How do we PREVENT an infestation of psoroptes ovis?
• To prevent infestation
1% MOXIDECTIN injection protests 28 days
Moxidectin injection long acting – protects 60 days
OR Organophosphate dip (Diazinon dip) ONLY PRODUCTS LICENCED FOR PREVENTION+ treatment - protect for approx. 60 days
QUARANTINE , treat sheep returning from show/ market, disinfect shearing equipment/ transport, prevent contact with double fencing
Treatment psoroptes bovis why harder to treat than ovis?
• Bovine Psoroptic mange is hard to treat as resistant to MLs like ivermectin and Moxidectin
clinical signs psoroptes bovis
- Aural haematomas (flicking and scratching ears)
- Lesions neck, back, shoulders, flank – wool loss
- Weight loss and lamb born to
- Intense prutitis
- Intense irritation, 30% decreased weight gain, epileptiform severe = seizures if touched
Untreated = death
List the burrowing and non burrowing mites that affect dogs and cats
Non-burrowing mites: Otodectes cynotis, Cheyletiella spp and Trombicula autumnalis
Burrowing mites : sarcoptes scabiei, Notoedres spp and Demodex spp
How to treat cheyletiellosis, what causse it?
• Lesions typically occur dorsally, on the rump and shoulders (‘walking dandruff’)
• Common in rabbits. In dogs, infestations possibly more prevalent in Boxers and Cocker spaniels – don’t know why
• Control:
o No licensed products to control
Probably because not such a severe issue
o Treatment: Fipronil (dogs and cats); ivermectin (rabbits NOT dogs as CNS sensitivity!)
Otodectes cynotis
Most common mange mite of cats and dogs, found in the ear canal
• Non-burrowing
• Life cycle ~ 3 weeks;
• Transmission is by direct contact
• In cats, signs often a brownish waxy exudate, with crusting.
Causes intense itching, with head shaking
• Causes intense itching, with head shaking
• Secondary bacterial infection can result in purulent otitis externa – dark brown exudate
o Sample of this might have mites
• 50-80% of such cases of otitis externa are associated with Otodectes cynotis
• Control: various drops - e.g permethrin (dogs only, toxic to cats). Requires frequent reapplication
• Imidacloprid; selamectin
• Treat all in-contact dogs and cats in the household
How does chorioptes affect horese?
Affects the feet of horses in colder months, especially those with feathered fetlocks. Cattle = base of tail, neck, head and udder
• Feed on scales and debris
• A winter disease
• The 6-legged larva hatches from the egg laid on skin and feeds and moults through to 8-legged protonymph, tritonymph and adult stages.
• Life cycle approx 3 weeks; mites may survive for up to 3 weeks off their host
Causes hair loss, prutitis and scaline. Usually mild, occurs around housing time
