Dairy Cattle Skin Lesions

Question 1

What is the term for the disease caused by Trichophyton verrucosum?

Answer 1

(Ringworm/dermatophycosis)

Question 2

What is the most common causative agent of ringworm?

Answer 2

(Trichophyton verrucosum)

Question 3

Why is it important to know that Trichophyton verrucosum is spore forming?

Answer 3

(This is the causative agent for ringworm, spore forming indicates that it will live in the environment for a long time)

Question 4

(T/F) You cannot write a health certificate for an animal with ringworm.

Answer 4

(T, both transmissible and zoonotic)

Question 5

Why do ringworm lesions typically pop up on the head and neck in cattle?

Answer 5

(Bc they communicate with each other and the world with their heads → rub on stuff, lick stuff, etc.)

Question 6

Are ringworm lesions typically pruritic?

Answer 6

(No)

Question 7

What should you assess in a cow with extensive ringworm lesions?

Answer 7

(Immune function, could indicate there is immune compromise such as BVDV PI, chronic lymphoma, etc.)

Question 8

(T/F) Ringworm is not associated with any production losses in cattle.

Answer 8

(T)

Question 9

Using topical clotrimazole is an option for treatment of ringworm in cattle, what is the meat withdrawal period?

Answer 9

(24 hours/1 day)

Question 10

What will indicate if a ringworm lesion is no longer infected and is healing?

Answer 10

(When hair is growing back in the middle of the lesion)

Question 11

What is the pathophysiology behind primary photosensitization?

Answer 11

(Animal obtains a photodynamic agent (from ingestion, injection, or absorption) which then reacts to UV light in the skin, free radicals are released which damage cell and lysosomal membranes of skin cells causing ulceration, necrosis, and edema)

Question 12

Why does primary photosensitization only affect the non-pigmented skin of cattle?

Answer 12

(Because pigmented skin contains melanin which is protective against the UV light needed to react with the photodynamic agents)

Question 13

Photosensitization is more likely to affect dairy/beef (choose) cattle and why.

Answer 13

(Beef, they are out on pasture and exposed to the sun)

Question 14

What two forages primarily cause primary photosensitization?

Answer 14

(Legumes and Brassica)

Question 15

What antibiotic does Dr. Guynn suggest for use in cases of primary photosensitization that she usually doesn’t use in beef cattle?

Answer 15

(Excede → works on skin lesions and lasts a long time)

Question 16

Why is the prognosis poor for secondary photosensitization when it is good for primary photosensitization?

Answer 16

(Because secondary is associated with liver damage, not a lot to do to fix the liver in cattle)

Question 17

Why is bovine ulcerative mammilitis associated with cold weather?

Answer 17

(Because the virus that causes it (bovine herpes virus II and IV) replicates at lower temperatures)

Question 18

The use of what type of PPE is important for preventing the spread of pseudocowpox from cattle to humans?

Answer 18

(Gloves)