Equine derm cases Flashcards
Case 1 – ROGER
Signalment:
- 2 year old TB gelding
- Presenting complaint: Scaling and crusting on hindlimbs
History:
- Has been 3 weeks at a large racing yard in order to start training
- Yard has 80 horses, a couple of others have similar lesions elsewhere on their bodies
- Horse bright, working/eating well
- Not apparently pruritic
Management:
- Stabled in a block of 10 horses, the dividing walls are partly solid and partly mesh
- The stable lads look after 5 horses each and they could be in different blocks
- Horse is rugged at night
- Horses share some tack but have their own grooming kits
- Fed haylage from hayracks and a complete diet 3 times per day with added supplements.
- Bedded on shavings
Clinical findings
- General clinical examination other than skin WNL
- However, poor haircoat
- Multiple focal areas of scaling and crusting, some circular, others irregular in shape, present mostly on lateral aspects of both hindlimbs
- Large scabs standing out from the coat
- Horse painful and resented hair plucking from the lesions
- No pus under the scabs
- No pruritus noted
What are your differential diagnoses for this case?
How would you investigate this case further to rule your DDX in or out?
What treatment and management options do you advise the Head Lad to implement?
What are your differential diagnoses for this case?
- Dermatophytosis- Microsporum spp. ( M. Gypseum or M. Equinum) Or Trichophyton spp(T. Equinum or T. Verrucosum)
- Staphylococcal folliculitis (tend to be smaller pinpoint scabs)
- Eosinophilic folliculitis
- Dermatophilus congolensis (rain scald/mudfever)
- Demodecosis ( V. Rare)
- Pemphigus foliaceus ( Rare)
How would you investigate this case further to rule your DDX in or out?
- Hair plucks
- Skin scrapes
- Bacterial and fungal culture of hair plucks/scabs
- Impresssion smears of scabs
- Skin biopsy
What treatment and management options do you advise the Head Lad to implement?
Diagnosis: DERMATOPHYTOSIS (doesn’t always happen in expected places in this horse it was on legs mainly)
Treatment and management:
2 main aims of TX:
- TX of active infection and reduction in spore formation
- Eradication of infective spores from the environment
- ID of spp not really important for tx
- Incubation period 6 days to 6 weeks
- Most infections are self limiting within 3 months
- Zoonotic disease- wear gloves to handle animal at all times
- Burn all hair, scabs etc from infected horses (don’t let it litter in the bedding)
- Follow any manufacturers instructions very carefully
- Horses cannot enter a racecourse with active lesions
- Remove scabs, crust and scale as these will contain a lot of spores
Topical TX- important to reduce progression of lesions and to limit spores; Imaverol (enilconazole), Mycophyt (natamycin) or Malaseb (miconazole+chlorhexidine). First 2 are liscenced in horse. ?? 10% povidone iodine solution
Systemic TX: Griseofulvin granules, licenced in horse, not in pregnant animals as teratogenic- expensive, takes 5days to get into skin (slow), only anecdotal , no scientific evidence it works!
All tack, grooming equipment, rugs should be for that horse only and regularly sterilised by washing in anti-fungal or sporicidal disinfectant eg. Virkon or quarternary ammonium compounds eg. Trigene
Tricky to treat environment, consider Fogging or antifungal, spoicidal disinfectants, total elimination is unrealistic
General hygeine important. Wear gloves. Plastic girth covers. Plastic tack that can be dipped in virkon. Overalls and diff clothes and disinfection.
Case 2 – ANGUS
Management:
- Lives at a livery yard which is on a farm. Stabled in a barn with others at night, out in communal grazing paddocks by day
- Un-rugged at all times
- Bedded on straw
- Fed hay from ground and receives a commercial feed twice per day, has a mineral and salt lick in the stable
- No other concurrent medical issues reported, horse underwent and passed a 5-stage vetting prior to purchase
- All other in contact horses unaffected
- Farm had various free-range poultry including chickens, geese and ducks.
Signalment
- 10-year-old TB X, gelding
- Presenting complaint
- Pruritus
History
- Purchased by the owner in April 2 months ago, daughter’s first horse
- Within 3 weeks had started generally rubbing and biting itself anywhere it could reach and owner is very distressed by it
- Has had intermittent urticaria
- Is affecting its ridden work as stops to scratch and has once got down to roll in the middle of a lesson.
Clinical presentation
- When observed loose in stable horse rubs itself on both sides of his body against the walls
- Evidence of broken hairs above and including the tail head
- Multiple raised wheals over the neck, shoulder, brisket, trunk and ventrum which pit on pressure and are of varied size
- Some areas of alopecia with excoriations due to self-trauma, some fresh, some healing
What are your differential diagnoses for this case?
How would you investigate this case further to rule your DDX in or out?
What treatment and management options could be implemented?
What are your differential diagnoses for this case?
- Atopic dermatitis
- Dermatophyte infection
- Contact allergy
- food allergy
- mite allergy (dermanyuss galinae)- poultry, chorioptes, forage, dust, trombiculosis
- insect bite hypersensitivity
- Sweet itch (unlikley as doesn’t have classic clinical pattern)
- Cutaneous adverse drug reaction
- Infectious, immune mediated vasculitis
- Erythema multiforme
How would you investigate this case further to rule your DDX in or out?
- Superficial skin scrapes, hair plucks, coat brushings, tape strips
- Skin biopsy
- Intradermal skin testing (below)
- Serological allergy tests
What treatment and management options could be implemented?
Intradermal skin testing KEY POINTS:
- Limited number of studies done to determine optimum testing protocols
- Not all the same test allergens used, made by different companies so difficult to compare
- Do not use mixed allergens in tests
- False negatives- recent admin. Drugs Ideal WD before testing is not known but generally accepted rules are 3 weeks for oral and topical steroids, 8 weeks injectable steroids, 10 days for anti-histamines and products/diets containing omega 3/6.
Treatment and management
- Depends on most likely cause of atopy
- Make environment as allergen free as possible- bedding (rubber mats+shavings), no stabling next to horses on straw, that have dry hay, careful storage of feedstuffs, feed dust and mould free feeds and forage,remove other animals from environment, remove birdnests, careful cleaning of environment,
- Care with rug/tack/equipment washing
- Exclusion diets for feedstuffs, remove 1 at a time for min 1 month, note improvement or confirm with re-introduction
- Anti-insect rugs
- Allergen specific immunotherapy (ASIT)- drug therapy
- Reactions to IDST cannot be used to diagnose atopy but more to help plan avoidance and use ASIT.
- If impossible to avoid an allergen consider de-sensitisation programme, requires long term owner commitment and ability to inject own horse
- Topical therapy to physically remove dust, dander etc from the skin, weekly baths eg. Using Oatmeal based shampoos, hypoallergenic
- Systemic glucocorticoids, antihistamines, omega 6/3 fatty acids
Diagnosis: ATOPIC DERMATITIS DUE TO POULTRY FEATHER ALLERGY
Case outcome:
- Horse had a course of steroid tx- initially dexamethasone IM 0.1 mg/kg, then a descending course of oral prednisolone 1.0mg/kg SID PO 7 days, 0.75mg/kg SID PO 7 days, 0.5mg/kg SID PO for 7 days then 0.25mg/kg SID PO for 7 days.
- Horse moved to another livery yard, without any poultry
- Horse was absolutely fine and had no further problems with skin disease to my current knowledge !
Case 3 – PAULINE
Signalment:
- 9-year-old Thoroughbred cross mare
History:
- BIOP (been in owner possession) nine months
- Purchased with five-stage PPE examination with no points of concern
- Owner noticed a small “growth” on the inside of it right hind leg six months ago
Management
- Kept on a dairy farm with two other horses
- Turned out together during the day into a 2.5 acre paddock which is strip-grazed
- Stabled on straw overnight
Clinical presentation
See pictures
What are your differential diagnoses for this case?
Describe the lesions as accurately as possible assuming your most likely differential diagnosis is correct
What would be your next steps in the work-up of this case?
Describe a treatment protocol appropriate to the following scenario:
The horse is uninsured, and the owner is an avid reader of online forums and has decided not to use any veterinary products in the first instance. What non-prescription treatments are available?
The horse is insured but is extremely difficult to travel necessitating treatment at the yard?
The horse is insured but is extremely sharp with its hind legs such that direct physical examination of the lesions is extremely difficult despite heavy sedation?
What are your differential diagnoses for this case?
Sarcoids (all tumours on horses are sarcoids until proven otherwise except on a grey horse or around the eyes or vulva which are likely to see squamous cell carcinomas)
Differentials for the smaller alopecic lesion include: dermatophytosis, alopecia areata, local abrasion/trauma (rubbing), ectoparasites, insect bites
Differentials for the larger verrucose lesion: papillomatosis, hyperkeratosis, cheloid scar
Describe the lesions as accurately as possible assuming your most likely differential diagnosis is correct
What would be your next steps in the work-up of this case?
Biopsy typically not recommended as usually diagnosis easy by gross examination, and biopsy will not alter course of action. If you biopsy them you need to be prepared to treat.
Determine treatment protocol which can be aided by sending photographs to the University of Liverpool Sarcoid Referral Service
Describe a treatment protocol appropriate to the following scenario:The horse is uninsured, and the owner is an avid reader of online forums and has decided not to use any veterinary products in the first instance. What non-prescription treatments are available?
Non-prescription products include feed additives such as Sarc-Ex (ingredients: Guduchi vine, Creat, Eclipta, Hurricane Weed, Winter Cherry, Indian Gooseberry, Pig Weed, Chebulic myrobalan – you can make your own assessment of the likelihood of success) £26/kg
Blood root extract (Newmarket Bloodroot Ointment, Xxterra [US]) may be obtained without a prescription and some clinical evidence to suggest that it can be successful in treating some sarcoids. £40 per pot.
Owners also very fond of treatments such as turmeric and toothpaste
The horse is insured but is extremely difficult to travel necessitating treatment at the yard?
This is probably best treated using cytotoxic AW4-LUDES cream. After using the Liverpool Sarcoid Referral Service (£12) a course will be dispensed using 4-7 treatments, each 48-72h apart. Three strengths of cream are available and courses may include several different strength treatments. Total cost will be for the cream (£100-200), visit fees and typically sedation as application can become difficult. Overall cost likely to be £500-750. Overall success rate typically 70-80%.
The horse is insured but is extremely sharp with its hind legs such that direct physical examination of the lesions is extremely difficult despite heavy sedation?
This is probably best treated by laser excision under general anaesthesia. Laser excision is significantly more preferable than sharp excision as the wound bed consist of thermally damaged cells which will not support any neoplastic cells and also the effective margin of excision extends beyond the demarcation created at the time of surgery. Success for these types of sarcoids likely to be >95%. Cost £1000-1500 if performed under GA, approx £500 standing.
Case 4 – BARRY
Signalment:
- 4 year old Warmblood gelding
History:
- Recent history of mild respiratory infection approximately six weeks ago
- Responded well to a short course of a potentiated sulphonamides
Management
- The horse is on a small livery yard
- There are three other horses on the yard, all in their late teens
- A new horse arrived on the yard eight weeks ago, which was isolated for two weeks during which no clinical signs of disease were noted
Clinical presentation
- The horse is dull and depressed
- All four limbs show signs of diffuse oedema with serous discharge
- There are petechial haemorrhages visible on examination of the mucous membranes
- There is extensive ventral oedema mainly present in the axilla
What are your differential diagnoses for this case?
How would you investigate this case further to rule your DDX in or out?
What treatment and management options could be implemented?
What is your prognosis for this case?
What are your differential diagnoses for this case?
- Differentials should include all causes of vasculitis (including EVA Equine viral arteritis and EIA Equine Infectious anaemia) and is typically secondary to Streptococcal infection but can be secondary to equine influenza
- Purpura hemorrhagica
http://vetbook.org/wiki/horse/index.php/Purpura_hemorrhagica
How would you investigate this case further to rule your DDX in or out?
- Gold standard diagnosis by biopsy and histopathology (aseptic vasculitis, tissue IgG and activated complement
- Streptococcal antigen ELISA
Supportive diagnosis:
- Haematology: neutrophilia/leucocytosis
- Biochemisty: hypoproteinaemia, elevated fibrinogen, raised CK/AST, possibly raised urea and creatinine
What treatment and management options could be implemented?
- Aim to treat underlying infection and reduce immune-mediated response
- Procaine penicillin BID/Penicillin G
- Dexamethasone or prednisolone
- Supportive care may include IV fluid therapy, plasma transfer
What is your prognosis for this case?
- Depends upon the severity of the lesions and how promptly treatment can be initiated. In this case prognosis likely to be fair to good (some authors report >90% survival with aggressive treatment)
What is Purpura hemorrhagica?
- Purpura haemorrhagica is a rare complication of equine strangles and is caused by bleeding from capillaries which results in red spots on the skin and mucous membranes together with oedema (swelling) of the limbs and the head. Purpura hemorrhagica is more common in younger animals.
- Horses that develop purpura hemorrhagica usually have a recent history of strangles (infection with Streptococcus equi subsp. equi) or vaccination (intramuscular or intranasal) for strangles. It is thought to be caused by an auto-immune reaction where antibodies against the S. equi M- or R-protein cross-react with proteins on endothelial cells. This results in vasculitis, leading to subsequent severe peripheral edema in the legs and ventral abdomen, as well as petechiation or ecchymoses over the mucous membranes
- Treatment usually involves high doses of steroids such as dexamethasone. While high doses of steroids may risk laminitis, low doses are associated with refractory cases.[2] Antibiotics are used to treat any residual nidus of S. equi. Non-steroidal anti-inflammatory drugs (NSAIDs), such as phenylbutazone or flunixin, may be useful to reduce fever and relieve pain. Intravenous DMSO is sometimes used as a free-radical scavenger and anti-inflammatory. Additionally, wrapping the legs may reduce edema and skin sloughing.[2] Supportive care with oral or IV fluids may also be required.
