Dermatology Flashcards
What is the causative agent of rain scald?
Dermatophilus congolensis- gram positive, non-acid fast, filamentous aerobic bacterium
What is required for rain scald to develop?
A carrier animal, moisture in the environment, and skin lesions on the new recipient
How is rain scald transmitted?
Direct contact with fomites, flies, or ticks + moisture
What are the unique locations kids develop rain scald at?
Ear pinna, under the tail
What do the gross lesions from rain scald look like?
Thick crusts under the hair coat with pink, moist skin underneath in a classical paintbrush shape
How is rain scald diagnosed?
Impression smear with “railroad track cocci”, bacterial culture, or histopathology with thick crust with alternating layers of thick stratum corneum and presence of neutrophils
How is rain scald treated?
Remove animals from wet environment, remove crusts (and dispose of), wash lesions, administer parenteral oxytetracycline +/- NSAIDs
What is the usual presentation of an animal with fibropapillomas?
Young (<2yr) animals with lesions mostly over face and neck (can be teats, penis, interdigital, or alimentary tract), spontaneously regress after about a year
What are the treatments for papillomas?
Crushing, pinching, surgical removal, or cryotherapy, if many animals are affected, you can use an autogenous vaccine
What is the causative agent of bovine herpes mammillitis?
Bovine herpesvirus type 2
What are the clinical signs of bovine herpes mammillitis?
Teat, oral, udder, or generalized skin lesions, starting out painful and edematous and progressing to ulcerative +/- vesicles, develop secondary bacterial infection and mastitis
How is bovine herpes mammillitis diagnosed?
Serology, virus isolation, or histopathology
How is bovine herpes mamillitis treated?
Milk cows last and wash hands between cows, parenteral antibiotics if secondary bacterial infection present
What kind of virus is pseudocowpox?
A parapoxvirus
Describe pseudocowpox
Lesions start as small papules and progress to large circular lesions consuming the teat, scabs develop with horseshoe shape; thighs, scrotum, and mammary gland are commonly affected, no systemic illness. Zoonotic- can appear on hands of milkers.
What kind of virus causes sheeppox and goatpox?
A capripoxvirus
Where are sheep and goat pox commonly seen?
Africa, Asia, Middle East
What are the clinical signs consistent with sheep/goatpox?
Pyrexia, anorexia, conjunctivitis, rhinitis, skin lesions
What is the morbidity and mortality of sheep pox? What about goat pox?
Sheep pox- high morbidity, high mortality
Goat pox- high morbidity, low mortality
How is sheep/goat pox treated and controlled?
Vaccine may be available for severely affected herds
Zoonotic so be careful
What is the causative agent(s) of dermatophytosis in ruminants?
Trichophyton verrucosum and Trichophyton mentagrophytes
How is ringworm transmitted?
Direct contact, more common in younger animals
What is the incubation period of ringworm?
1-6 weeks
What is the duration of disease from ringworm?
1-4 months
Describe the pathophysiology of ringworm
Dermatophyte invades fully keratinized non-living tissue on the axilla, trunk, rump, neck, limbs, and face. May cause pruritis, crusting, or wart-like appearance.
How is ringworm diagnosed?
Fungal culture of broken hairs
How is ringworm treated?
Topical shampoos with miconazole, ketoconazole, or 3-4% chlorhexidine
Vaccine available in Europe, not in USA
What is the biting species of lice?
Mallophaga
What is the sucking species of lice?
Anoplura
How is lice diagnosed and treated?
Observation of the lice
Treat with ivermectin (sucking) or topical insecticide- pyrethroids, permethrins, fipronil (sucking or biting)
What are the four types of mange?
Psoroptic, chorioptic, sarcoptic, demodectic
What species cause psoroptic mange?
Psoroptes equi, ovis, natalensis, and cuniculi
Describe psoroptic mange
Mites live on the surface of the skin and cause pruritis, spreading across the body and decreasing productivity, causing weight loss, and causing secondary bacterial infection. Diagnosed with skin scraping. Treat with ivermectin, doromectin, or moxidectin
What species cause chorioptic mange?
Chorioptes bovis, texanus, ovis, equi, and capre
Describe chorioptic mange
Occurs in cattle and sheep, has 2-3 week life cycle, causes varying levels of pruritus, usually on extremities and perineum region. Can be diagnosed with skin scraping, treated with ivermectin, doromectin, or moxidectin.
What species causes sarcoptic mange?
Sarcoptes scabiei
Describe sarcoptic mange
Uncommon in ruminants, zoonotic, eggs deposited within epidermis, mostly affects head and neck with severe pruritus. Don’t need a lot of mites to cause severe disease, so negative skin scrape doesn’t rule out disease. Treated with ivermectin. Reportable disease.
What species causes demodectic mange?
Demodex bovis, ovis, and caprae
Describe demodectic mange
Mites live in hair follicles, sebaceous glands, and sweat glands, causing nodular lesions of face, shoulders, and neck (also periocular in sheep). Diagnose with skin scrape. Treatment is difficult, but use pour-on or injectable ivermectin
What species cause warbles (Hypoderma)?
Hypoderma bovis and lineatum
When in the year are hypoderma active?
Spring and summer
Where do H. lineatum deposit eggs? Where do H. bovis deposit eggs?
H. lineatum- hair of legs or lower body
H. bovis- rump or upper hairs on hind limbs
Describe the pathogenesis of hypoderma
Eggs hatch in 3-7 days; L1 penetrate skin, migrate through tissues (lineatum -> esophagus; bovis -> spinal canal) where they stay for 2-4 months. In January, final migration begins and they go back to dermal tissue on the backs of the animal where they bore breathing holes and develop cysts. They molt twice and L3 emerge, fall to the ground, pupate, and turn into flies who mate.
What are the clinical signs of hypoderma?
Stampeding behavior/self-trauma in the summer, fat necrosis or esophageal tissue edema during L1 migration, warbles on rump and dorsum during L3 stage
How is hypoderma treated?
Individual worm removal, pour-on doramectin, eprinomectin, ivermectin, or moxidectin in early fall
How does a cow with copper deficiency look?
Has dull haircoat, ill-thrift, chronic diarrhea
How is copper deficiency diagnosed?
Measure copper in serum or liver
Describe zinc responsive dermatosis
Affects cattle, sheep, goats, and llamas. Caused by low zinc or antagonist in diet, also hereditary. Clinical signs- dull haircoat, scaling, alopecia, hyperkeratosis. Diagnosed with plasma zinc levels and histology showing parakeratosis as well as response to treatment. Treat with zinc supplementation.
What is the presentation of orf?
Oral, muzzle, teat, vulva, coronary band, and conjunctiva lesions, painful papular/vesicular/pustular lesions that scab, shrink in 2-3 weeks, and fall off in 4-6 weeks
How is orf transmitted?
Direct contact, contact with scabs or saliva
How is orf diagnosed?
Signalment/lesions, histopathology, FAT
How is orf treated and prevented?
Nursing care, isolate animals, vaccinate at 2-3 days old (only on endemic farms)
