Skin Lesions

Question 1

What organism is responsible for ring-like lesions of the skin?

Answer 1

trichophyton verrucosum, a spore-forming zoonotic fungus that can live in the environment for a long time due to the protection of the spores.

Question 2

T/F: you are able to write health certificates for animals with dermatophycosis because this infection is easily cleared.

Answer 2

false. its classified as a transmissable infectious disease. It can be passed from animal to animal, as well as from fomites to animals, so its important that these animals stay away from others during the course of the infection.

Question 3

Which of the following is FALSE about ringworm in cattle?
A. it occurs in younger, confined animals, but in older animals is extensive d/t probable immune compromise
B. it typically starts on the head and neck
C. it is characterized by grey, scabby areas with no hair
D. the lesions are pruritic

Answer 3

D. the lesions are pruritic

they are not usually itchy

all of the rest of the statements are TRUE of ringworm.

Question 4

Which of the following is TRUE about ringworm?
A. it is not self-limiting and requires topical treatments for clearance
B. there are no production losses associated with infection
C. treatment entails topical antibiotics such as gentamicin
D. it does not persist in the environment, so there is no need to clean the barn or tools with bleach

Answer 4

B. there are no production losses associated with infection (unless there is underlying disease)

Ringworm IS self-limiting, but you can apply topical treatments. First, you want to scrape off the scabs (dispose of them carefully), wash with gentle soap, wash with 2-4% iodine solution 2x/day for 1-2 weeks, and apply clotrimazole. Note that this has a 24 hr meat WD.
It is recommended that you do clean the barn and tools with 1:4 bleach because this organism persists in the environment due to spore formation

Question 5

How do you determine if a ringworm lesion is healed?

Bonus for the UNRELIABLE way to determine if its healed

Answer 5

if hair is growing back in the middle of the lesion

unreliable way: free of crusts

Question 6

Why is DTM media rarely used to diagnose ringworm in production animals?

Answer 6

it can take 3-6 days to show positive.

Question 7

What are the 3 most common plants that cause primary photosensitization?

Answer 7

1. buckwheat
2. st johns wort
3. smartweed

Question 8

___________ is ingestion, injection, or absorption through the skin of a photodynamic agent.

Answer 8

primary photosensitization

Question 9

Describe how a photodynamic agent causes primary photosensitization

Answer 9

high energy molecules react with UV light within the skin and release free radicals
the free radical damage the outer cell membrane and the lysosomal membranes of skin cells which leads to skin ulceration, necrosis, and edema.

Question 10

T/F: primary photosenitization occurs in healthy cattle on non-pigmented skin, the nose, and the udder.

Answer 10

true
because melanin is what protects from the UV light, therefore lack of melanin does not provide any protection.

Question 11

What are forages that can cause primary photosensitization?

Answer 11

1. legumes
2. brassica

Question 12

How does chlorophyll play a role in primary photosensitization?

Answer 12

if cattle eat dry hay then are turned into lush green pastures, they intake far too much chlorophyll.
The liver is overwhelmed, so the excess chlorophyll turns into phylloerythrin by microorgnisms in the GIT and causes photosensitization in the skin.

Question 13

You are treating a few holsteins that have primary photosensitization. What is your plan?

Answer 13

1. stop their intake of the plants/forage/lush grass
2. provide them shade
3. prevent secondary infections and provide pain relief (banamine or meloxicam + excede)

Question 14

___________ is associated with inherited abberrant pigment metabolism which affects both unpigmented and pigmented skin.

Answer 14

type II photosensitization (congenital erythropoietic porphyria and bovine erythropoiteic protoporphyria)

Question 15

You are called to a farm to investigate the cause of an ill holstein.
On exam, you note this cow has icteric membranes and lesions with hair loss along the white colored hair , as well as some of the black patches. You diagnose this patient with secondary photosensitization.

What caused this condition to occur?

Answer 15

this cow must have had impaired hepatobiliary secretion.
This could be due to many things:
1. a bile duct occlusion (ex. flukes)
2. hepatic dysfunction due to toxins (pyrrolizidine alkaloids in senecia or crotolaria; blue green algae)
3. hepatic dysfunction due to infections

Question 16

how can you PREVENT photosensitization from occuring?

Answer 16

1. provide appropriate quantities of forage and feed
2. improve pasture and limit weeds or access to them
3. provide shade

Question 17

Which of the following statements is FALSE about bovine ulcerative mammilitis?
A. treatment includes debriding necrotic teat tissue and likely culling her due to inability to produce milk.
B. it causes decreased milk production and increased incidence of mastitis
C. it causes painful edematous, ulcerated lesions or vesicles that rupture on the udder
D. it can be associated with cold weather
E. cows with this condition should be milked last

Answer 17

A. treatment includes debriding necrotic teat tissue and likely culling her due to inability to produce milk.

Treatment includes iodophore teat dips with emollients and isolation of the affected cows. You must milk these cows last or use separate equipment.
But debridement/removal of tissue is NOT necessary and she will likely heal and be able to produce milk in the near future.

Question 18

Which of the following statements is MOST correct about pseudocowpox?
A. it is also known as contagious ecthyma
B. infected animals develop life-long immunity and dont typically become reinfected
C. this infection is zoonotic and can produce painful scabs on human hands/arms
D. lesions persist short-term (1-2 weeks), heal as the virus becomes latent, and then lesions reappear several months later

Answer 18

C. this infection is zoonotic and can produce painful scabs on human hands/arms

Pseudocowpox is a parapoxvirus that is RELATED to contagious ecthyma, not equivalent to.
The virus creates small red papules to vesicles/pustules. Small scabs will form around the granulation tissue.
Lesions will persist for several MONTHS. Animals have SHORT immunity so reinfection is possible.
This condition is zoonotic, so humans should wear gloves when milking.

Question 19

What virus causes bovine warts?

Answer 19

papillomavirus

Question 20

You are called to a dairy farm because this farmers cows have small, raised, non-painful lesions on their teats. You examine these lesions and they are filamentous/frond-like.
You diagnose this patient with bovine warts (papillomavirus).

Why might they require excision?

Answer 20

because if they are larger or on teat end, they can interfere with milking.

They are also contagious and can be transmitted directly or indirectly (fomites).

Question 21

Describe the following scores for the stages of teat hyperkeratosis:
A. Stage 1
B. Stage 2
C. Stage 3
D. Stage 4

Answer 21

A. Stage 1 – normal teat end with NO ring around teat canal
B. Stage 2 – smooth raised ring or slightly rough ring with no keratin fronds.
C. Stage 3 – raised, rough ring with isolated fronds of old keratin extending 1-3 mm from the orifice. There is some breakdown of epithelial integrity
D. Stage 4 – raised ring with rough fronds of old keratin extending >4 mm from the orifice. The ring is rough and cracked giving the teat end a flowered appearance.

Question 22

Why are higher stages (3 and 4) of teat hyperkeratosis concerning?

Answer 22

these stages increase the risk of developing intra-mammary infections such as mastitis
this is because the teat end cannot form a seal and the crusts that develop have the potential to wick staph and other bacteria into the teat end.

Question 23

Which of the following is NOT a risk factor for teat-end hyperkeratosis?
A. long, pointy teats
B. younger cows
C. later lactation
D. longer milking times (high production, slow milkers)
E. genetics
F. higher vacuum machine
G. more movement in the liner of the milking machine
H. higher frequency of milking

Answer 23

B. younger cows

older cows are at more of a risk

Question 24

What is the prevention for teat-end hyperkeratosis?

Answer 24

1. ensure proper milk let down (appropriate milk timing and appropriate claw attachment)
2. adjust automatic take offs
3. teat cleansing and post-dips with emollients

Question 25

Which of the following statements is FALSE about udder edema?
A. it occurs due to impaired blood and lymph circulation
B. it occurs more frequently in heifers than cows
C. it is multifactorial (genetics and dry cow nutrition)
D. it can cause moist dermatitis on the medial portion of the pelvic limbs
E. it can occur as a result of increased protein oncotic pressure as IgGs are put into the udder during late gestation

Answer 25

E. it can occur as a result of increased protein oncotic pressure as IgGs are put into the udder during late gestation

it can occur as a result of DECREASED oncotic pressure as IgGs are put into the udder during late gestation.

Question 26

You are called to a farm with a few dairy cows that have udder lesions. On exam, you see that there is necrotic, foul-smelling scabs between the two halves of the udder. You diagnose this patient with udder cleft dermatitis. How do you treat this patient?

Answer 26

1. clean with antibacterial daily
2. dry thoroughly
3. apply mild astringent (witch hazel, alcohol)

Question 27

T/F: granulomas can form as a result of udder cleft dermatitis

Answer 27

true

you should NOT cut it off because it will bleed a lot. these lesions are usually non-painful.