Farm Animal Skin Disease

Question 1

What primary skin and coat lesions affect farm animals?

Answer 1

Parasitic - lice, mites
Bacterial - erisipelas, dermatophilus
Viral - CSF,PDNS/PRRS
Fungal - ringworm

Question 2

What are the secondary causes of skin or coat lesions in farm animals?

Answer 2

Underlying disease or deficiency

Question 3

How is diagnosis of skin disease achieved in farm animals?

Answer 3

History (housed or not, signalment, time of year)
Clinical presentation
Skin scrapings
Microbiology
Case vs herd

Question 4

What external parasites affect farm animals?

Answer 4

Lice, Mites, Flies, Midges, Ticks

Question 5

What parasites affect cattle? What are their treatments?

Answer 5

Sarcoptic mange - macrocyclic lactones (MLs)
Psoroptic mange - permethrin pour-on product/MLs
Chorioptic mange
Demodectic mange
Warble fly - notifiable

Question 6

What are the characteristics of chorioptic mange?

Answer 6

Causes tail mange affecting hindlegs, udder, perineum, tail mostly in housed cattle with mild pruritis

Question 7

What are the characteristics of demodectic mange?

Answer 7

Rarely diagnosed, problem for hide damage, no pruritis and little hair loss
Occasionally develop into multiple nodules +/- secondary infection

Question 8

What are the parasites that affect the skin of sheep?

Answer 8

Lice - Bovivola ovis (biting), Linognathus ovillus (sucking)
Mites - Sarcoptes scabei, Demodex ovis, Psorobia ovis, Chorioptes bovis, Psoroptes ovis
Blow fly strike

Question 9

What are the clinical signs of sheep body lice?

Answer 9

Severe fleece derangement
Rubbing, biting wool
More important in Merino and Merino types
Increased incidence in UK since dipping stopped

Question 10

What is the epidemiology of sheep body lice?

Answer 10

Numbers increase in long wool
Decline dramatically at shearing
Reduced by solar radiation unless protected by the fleece

Question 11

How is diagnosis and treatment of sheep body lice achieved?

Answer 11

Part the wool and examine near the skin
Shear the sheep
Apply insecticides by pour-on or saturation dip

Question 12

What are the clinical findings of psoroptic mange in sheep?

Answer 12

Pustules then spreading moist lesions, fleece becomes matted with extreme pruritis
Can become very extensive
Mites visible with naked eye
If severe sheep become very thin and die

Question 13

What is the epidemiology of sheep scab (psoroptic mange)?

Answer 13

Mites can multiply very rapidly, winter is more favourable, sometimes infestations are latent over summer

Question 14

How is sheep scab diagnosed?

Answer 14

Scrapes from periphery of lesion

Question 15

How is treatment and control of sheep scab achieved?

Answer 15

Plunge dipping in OP solution
MLs by injection with repeat dose (ivermectin SC 7 days apart at 200ug/kg) or long acting (doramectin IM once at 300ug/kg)
Pastures, fences, buildings are a source of reinfection for up to 15 days

Question 16

What are the predilection sites for blowfly strike in sheep?

Answer 16

Breech, body, wounds, head (base of horns)

Question 17

What is the pathogenesis of blowfly strike in sheep?

Answer 17

Larvae feed on the skin surface causing extensive skin damage
Toxaemia follows due to skin necrosis and absorption of bacterial toxins
Secondary and tertiary flies may invade

Question 18

What is the treatment for blowfly strike in sheep?

Answer 18

Clip surrounding hair, clean tissues, remove visible maggots, apply insecticide
Supportive therapy of antibiotics and NSAIDs in severe cases

Question 19

How is blowfly strike prevented in sheep?

Answer 19

Tail-docking of lambs and cyromazine

Question 20

What lice do pigs get?

Answer 20

Haematopinus suis which is very large and can transmit African Swine Fever and Swine Pox

Question 21

How is pig lice treated?

Answer 21

OPs twice at 14 day intervals

Question 22

What mites do pigs get?

Answer 22

Sarcoptes scabei causing a serious painful condition and if chronic hyperkeratinisation is severe

Question 23

How are pig mites treated?

Answer 23

Ivermectin but several doses needed

Question 24

What species are affected by dermatophilosis?

Answer 24

Sheep, camelids, goats, pigs and rarely cattle

Question 25

What are the clinical signs of dermatophilosis in farm animals?

Answer 25

Lumpy wool in sheep

Produces crusts of varying thickness on wooled and/or haired skin and tends to follow wet weather

Question 26

How is diagnosis of dermatophilosis achieved in farm animals?

Answer 26

History and clinical signs

Smears from scabs with saline/KOH air dried and stained with Diff-Quik and look for characteristic railroad tracks

Question 27

How is dermatophilosis treated in farm animals?

Answer 27

Bring affected animals out of wet environment
Correct any underlying problems
Systemic antibiotics (penecillin or oxytet)
Topical treatment with chlorhexidine scrubs

Question 28

What are the characteristics of ringworm (dermatophytosis) in farm animals?

Answer 28

Self-limiting usually resolving within 1-3 months

Question 29

What is the treatment for ringworm in farm animals?

Answer 29

UV light

Imaverol with 3-4 treatments 3 days apart