Pruritus and Allergy 2

Question 1

4 main manifestations of allergic skin disease in cats.

Answer 1

Self-induced alopecia/hypotrichosis.
Miliary dermatitis (papular dermatitis).
Head and neck pruritus.
Eosinophilic granuloma complex.

Question 2

1. Signs of head and neck pruritus.

Answer 2

1. Particularly severe pruritus.
   Excoriation, erosion, ulceration.
   Blepharitis.
   Wounds from scratching.

Question 3

Miliary dermatitis signs.

Answer 3

Crusted papules.
Easier to feel than see.
Typically on back.
Sometime self-induced alopecia.
Common with flea bite hypersensitivity.
- not specific. Can see other patterns too.
Can be seen with food allergy.
Feline atopic skin syndrome.

Question 4

Miliary dermatitis differential diagnoses.

Answer 4

Allergic skin disease.
Ectoparasites - lice, Cheytiella, Otodectes and Trombiculid mites. Rarely Notoedres and demodicosis.
Dermatophytosis and rarely bacterial folliculitis.
Pemphigus foliaceus (autoimmune).
Other rare diseases e.g. drug eruptions.

Question 5

Eosinophilic granuloma complex.

Answer 5

Includes:
- eosinophilic ulcer.
- eosinophilic plaque.
- eosinophilic (linear) granuloma.
Each has distinct clinical pattern/presentation.
Different reactions patterns to the same underlying cause.
All three may be observed in the one cat.
Expect to find eosinophils on cytology.

Question 6

Eosinophilic plaque.

Answer 6

Manifestation of allergic skin disease.
Pruritic, raised, often ulcerated.
Found anywhere on the body.
- often ventral abdomen and medial thighs.
Lesions may be seen concurrently with:
- miliary dermatitis.
- eosinophilic granuloma of the chin.
Tends to be seen in younger cats.

Question 7

Investigation of eosinophilic plaques.

Answer 7

Investigate underlying cause:
- fleas?
– treatment trial.
- elimination diet trial.
- feline atopic skin syndrome.

Question 8

Eosinophilic (rodent/indolent) ulcer.

Answer 8

Distinct well-demarcated unilateral or bilateral ulcers.
At philtrum of upper lip or adjacent to upper canine tooth.
Large lesions - may cause facial distortion.
Pain and/or pruritus rare.
Can occur alongside other reaction patterns.

Question 9

1. Investigation of eosinophilic ulcer?
2. Treatment of eosinophilic ulcer?

Answer 9

1. Consider biopsy to rule out neoplasia and bacterial / fungal infections for chronic lesions.
2. Small single lesions may not need treatment.
   May be a manifestation of allergic skin disease so treat the underlying cause.
   May need abx for more extensive disease.
   - if significant secondary infection or for the immunomodulatory effect.
   - question if oral abx actually needed and appropriate.

Question 10

Eosinophilic (linear) granuloma…
1. Associated with?
2. Pruritus?
3. Site of linear form?
4. Signs?

Answer 10

1. Allergic disease.
2. May/may not.
3. Caudal thigh.
4. Proliferative lesions in the mouth.
   Poorly defined chin swelling.
   Erosion / ulceration common.
   Associated with oral cavity - halitosis, anorexia, hypersalivation.

Question 11

1. Suspected causes of eosinophilic granuloma?
2. Most difficult forms to treat of eosinophilic granuloma? - why? – alternative?
3. Treatment for lesions elsewhere.

Answer 11

1. Allergic skin disease, mosquito bites?
2. Lesions in the oral cavity.
   - Difficulty to treat topically.
   – Sx debulking.
3. glucocorticoids, ciclosporin, maybe topical therapy if possible.

Question 12

Clinical signs of cutaneous adverse food reaction / food allergy in cats.

Answer 12

Non-seasonal pruritus.
- head and neck more common?
Any of the 4 reaction patterns.
May be concurrent flea bite hypersensitivity or feline atopic skin syndrome.
Can be associated with non-cutaneous signs:
- vomiting, diarrhoea, respiratory signs, conjunctivitis, hyperactive behaviour.

Question 13

Diagnosis of cutaneous adverse food reaction in cats.

Answer 13

Elimination of signs following elimination diet trial.
- Hydrolysed diets.
- Home cooked novel, single-protein.
- Commercial (dry) novel, single-protein.
Duration at least 8 weeks.
Confirm diagnosis by re-challenging.
- re-introduce original diet in its entirety.
- clinical signs recur within 7d.

Question 14

Challenges of elimination diet trials in cats.

Answer 14

Potential problems with palatability.
Cats can access other sources of food e.g. hunting, neighbours.
Difficult to evaluate a food trial in a cat allowed outdoors.

Question 15

1. Feline atopic skin syndrome age affected.
2. clinically similar to…
3. Treatment of feline atopic skin syndrome.

Answer 15

1. Young cats.
2. Food allergy.
3. May respond to allergen specific immunotherapy.
   - based on intradermal or serological allergen testing.
   – intradermal is a challenge –> results not as clear, recent drug therapy, inappropriate allergen selection/preparation, technical difficulties, may be delayed reactions.

Question 16

1. Licensed options for treatment of allergic skin disease in cats.
2. Other treatment options for allergic skin disease in cats.
3. factor to consider.

Answer 16

1. Glucocorticoids, ciclosporin.
2. Essential fatty acids, antihistamines, oclacitinib (apoquel) - safe?, allergen specific immunotherapy.
3. ease of admin in feline patients.

Question 17

Glucocorticoids in cats.

Answer 17

Injectable vs oral - half life.
Anti-inflammatory - initial dose 1-2mg/kg/day of preds.
Long term therapy - adverse effects.
– PUPDPP, weight gain?, DM, iatrogenic hyperadrenocorticism (e.g. skin fragility), infections (e.g. dermatophytosis, bacterial cystitis), demodicosis, GI signs.

Question 18

1. How does ciclosporin (Atopica) work?
2. What should be done before prescribing ciclosporin to cats?
3. Challenge of admin of ciclosporin to cats.
4. Adverse effects of glucocorticoids.

Answer 18

1. Calcineurin inhibitor - affects T cells.
2. Check for exposure to FIV/FeLV and Toxoplasma.
   - a toxoplasma naive cat on ciclosporin may be more likely to develop clinical signs of toxoplasmosis if exposed during treatment.
   - establish risk w/ hx - hunting etc?
3. Not palatable.
   Slow onset of action - ~4w or longer.
   – need to use concurrent tx e.g. glucocorticoids for first few weeks to ensure patient comfort.
4. vomiting, diarrhoea, lethargy, anorexia, hypersalivation - continued or stopped based on severity.

Question 19

1. Efficacy of ASIT in cats.

Answer 19

1. ~60%. At least 50% improvement in clinical signs, some may resolve.
   Likely to reduce and not replace other therapies.
   Underused likely due to a perceived difficulty of admin.

Question 20

1. Ectoparasites - insects.
2. Ectoparasites - Mites.

Answer 20

1. Fleas, flies (culicoides), lice.
2. Sarcoptes, chorioptes, psoroptes, Cheyletiella.

Question 21

Lifecycle of the cat flea (Ctenocephalides felis).

Answer 21

Most intermediate stages may be found in the host’s environment. Given chance, adult fleas will stay on the host but are usually removed by grooming or scratching esp. if hypersensitivity.

Question 22

1. Flea bite hypersensitivity.
2. Site of flea bite hypersensitivity?

Answer 22

1. Clinical condition of animals that have become sensitised to antigenic components of flea saliva.
   Immunopathogenesis in the dog is thought to involve type I and type IV (delayed) hypersensitivity reactions.
2. caudal dorsum.
   hindlimbs.

Question 23

Diagnosis of flea bite hypersensitivity.

Answer 23

History and compatible clinical signs.
Evidence of fleas or flea excreta in hair coat.
- often no signs of flea infestation.
- fleas and flea faeces removed by grooming.
- Evidence on in-contact animals.
Dipylidium caninum infestation (tapeworm) - flea is a vector.
Positive response to flea control programme.
Elimination of differentials.
Positive test response to intradermal / serology testing with flea saliva allergen? - NOT DIAGNOSTIC.

Question 24

Insecticides.

Answer 24

Neonicotinoids - Imidacloprid (e.g. Prinovox).
Isoxazolines - Afoxolaner (NexGard), Fluralaner (Bravecto), Lotilaner (Credelio), Sarolaner (Simparica).

Question 25

Factors influencing efficacy of flea control.

Answer 25

Formulation:
- shampoo/collar/spray/powder/spot-on.
Hair coat length.
Bathing/swimming.
Use of insecticidal products - on animal.
Action - e.g. growth development inhibitors:
– decrease viability of eggs.
– Pupae and pre-emerged adults remain unaffected and viable for long periods = “pupal window”.

Question 26

Mechanical control methods for ectoparasites.

Answer 26

Thorough vacuuming will remove:
- up to 20% of larvae and 32-59% of eggs.
- organic debris and flea faeces that are the nutritional support for flea larvae.
- vacuum before using environmental spray.
– increasing contact with larvae and pupae by aerating the carpet pile.
Carpet shampooing and steam cleaning NOT recommended - residual humidity ideal for hatching and larval development.

Question 27

Instances where flea control fails.

Answer 27

Failure to treat all animals in the house.
Failure to treat effectively with an on-animal product - frequency and appropriate application/administration.
Failure to remove the flea burden.

Question 28

1. Classic distribution of sarcoptic mange (scabies).
2. Dx of sarcoptic mange.

Answer 28

1. lateral elbows and hocks, feet, pinna.
2. superficial skin scrape.
   response to tx.
   - macrocyclic lactones and isoxazolines.
   Do not rely on histopathology/serology - need to correlate w/ hx and clinical signs.

Question 29

1. Signs of chorioptic mange in large animals.
2. Distribution in horses and predisposition.
3. Distribution on cattle.
4. Distribution on alpacas.
5. Dx of chorioptic mange in large animals?
6. How to differentiate chorioptes mites from psoroptes mites microscopically?

Answer 29

1. Pruritus, scaling, excoriation, crusting, alopecia.
2. Distal limbs - heavily feathered horses.
3. Tail base, distal limbs, udder.
4. Tail base, distal limbs, extension to ventral abdomen, medial limbs, ears.
5. Superficial skin scrapes at the margin of lesional areas - may need to clip e.g. feathered horses (also makes topical tx easier).
6. Chorioptes mites have cup-shaped suckers.

Question 30

Chorioptic mange treatment for most large animals.

Answer 30

Treat all affected and in-contact animals as well as the environment - carrier status.
Macrocyclic lactone, topicals (lime sulphur, fipronil = Frontline spray).
Duration of tx = 2 lifecycles = 6w.
Environmental management - bedding.
– Chorioptes bovis need host to survive long term.
– Chorioptes equi can survive off host for several weeks.

Question 31

Chorioptes therapy for camelids.

Answer 31

Macrocyclic lactones less effective in camelids? May need higher doses and longer tx course.
- Dose of ivermectin for ectoparasites in alpacas and llamas = 400micrograms/kg (double dosing) weekly – may be inaccurate weight.
Topical - not licensed.
- e.g. Fipronil spray, selenium sulphide shampoos, lime sulphur dips, keratolytic shampoos.
Tx often reduces rather than eliminates mites.

Question 32

How can you differentiate between chorioptic mange and lice in cattle?

Answer 32

Distribution:
- chorioptic mange = neck, tail base, distal limbs.
- lice = neck, dorsum, distal limbs.
Season = lice more apparent in winter months - housed so closer cow-cow contact.

Question 33

1. Signs of louse infestation - pediculosis.
2. Tx of pediculosis.
3. Lice = vectors of what?

Answer 33

1. Pruritus, alopecia, excoriation, self-wounding, anaemia.
2. Spot-on / pour-on.
   - synthetic pyrethroids.
   - macrocyclic lactones.
   In horses - depends on spp. of louse:
   - biting should respond to macrocyclic lactones.
   - sucking may require topical therapy as well e.g. cypermethrin. – distinguish by head shape.
3. Uncommonly vectors of various viral and rickettsial disease.

Question 34

1. Where is psoroptic mange notifiable?
2. Signs of psoroptic mange?
3. Dx of psoroptic mange?
4. Who should be treated if sheep present w/ psoroptic mange?

Answer 34

1. Scotland and Northern Ireland.
2. Can cause severe pruritus - welfare issue.
   Some can be asymptomatic.
3. Superficial skin scraping - look at crusts as well.
   Serology.
4. Whole flock - highly contagious.
   Risk resistance so ensure accurate dx.