SKIN

Question 1

Microsporum canis species for infection?

Answer 1

cat

Question 2

Microsporum gypseum

Answer 2

Microsporum gypseum is geophilic (meaning that it loves to grow in soil). This species often affects dogs that like to dig.

Question 3

Trichophyton mentagrophytes

Answer 3

richophyton mentagrophytes is zoophilic and usually rodents serve as the host; dogs such as hunting dogs or roaming cats are most commonly affected.

Question 4

An adult horse presents to you for recurrent seasonal pruritus during the summer months that seems to be worsening. On physical examination, you find multiple excoriations along the poll, mane, and tail. What is the most likely cause of this horse’s pruritus?

Answer 4

The correct answer is Culicoides. Culicoides hypersensitivity, also referred to as sweet itch, occurs due to allergy to the saliva of the gnat. It recurs seasonally in the warmer months and tends to worsen with age. Typically, horses are pruritic and develop lesions on the poll, mane, and tail from self trauma, although ventral midline dermatitis can occur as well. More chronically, scarring can occur. Treatment is to decrease exposure to the gnat and to treat with steroids. Habronemiasis is a condition where the larvae of the stomach worm migrate and emerge creating granulomatous lesions, usually around the eye, male genitalia, or lower extremities. Inside the granulomas, you can find dead larvae. Haematobia irritans is a bigger problem in cattle than horses (they reproduce in cow feces) but can affect horses, especially ones that are near cattle. It typically causes ventral midline dermatitis with wheals with a central crust that progress to alopecia and ulceration with fairly focal lesions, rather than more diffuse lesions caused by Culicoides. Onchocerca can cause dermatitis in the horse due to hypersensitivity to dying microfilariae. Lesions include alopecia and scaling of the ventral midline, face, and pectoral region. Often, lesions are diamond shaped and there may be a “bull’s eye” lesion on top of the head. Onchocerca is nonseasonal, in contrast to Culicoides hypersensitivity, and variably pruritic. Ocular lesions can also occur with Onchocerca including uveitis, conjunctivitis, and keratitis. Lastly, Hypoderma is also a bigger problem in cattle but can occur in horses and typically creates nodules on the dorsum that have a pore on top.