Farm Animal Dermatology Flashcards
What are the possible diagnostics available when it comes to dermatology?
- Skin scrapes
- Sticky tape
- Skin biopsy: including the edge of the lesion for both normal and abnormal histopathological comparison
- Whole lesion removal
When considering treatment for dermatological cases in farm animals, what must be considered?
1) Most chronic skin disease have a secondary bacterial dermatitis and therefore antibiotics are likely needed
2) Meat and milk withdrawals must be considered
3) The use of steroids in pregnant animals is contraindicated
4) Topical treatments are not practical on a herd/flock basis
What are the common and uncommon skin diseases of cattle?
Common:
- Besnoitia besnoiti
- Ectoparasites: Sarcoptic, Psoroptic, Chorioptes, Lice
- Photosensitization
- Ringworm
- Vitamin and trace element deficiencies/ toxicities
- Anagen Defluxion: stress-induced
- Genetic Skin Diseases: Follicular Dysplasia or Epitheliogenesis Imperfecta
- Immunological: Type 1 Hypersensitivity
- Cellulitis
- Cutaneous Actinobacillus
- Actinomycosis = Lumpy Jaw
- Bovine Papillomatosis
- Eosinophilic Granuloma
- Melanoma
- Toxic Gangrenous Mastitis
- Urticaria: Hives
Uncommon:
- Ergotism
- Cutaneous lymphoma
- Squamous Cell Carcinoma
- Type 2, 3, and 4 Hypersensitivities
What are the common skin diseases of sheep?
Common:
- Cobalt Deficiency
- Seasonal Allergic Dermatitis: hypersensitivity to Cullicoides bites
- Photosensitization
- Ringworm
- Psoroptes ovis = sheep scab
Besnoitia besnoiti is an ___________
Obligate intracellular protozoan parasite
How is Besnoitia Besnoiti transmitted?
- Still 100% unknown, but experimentally can be transmitted mechanically through blood-sucking insects
There are 2 distinct sequential clinical stages to the Besnoitia Besnoiti infection, what are they?
Acute Stage:
- Pyrexia
- Subcutaneous oedema
- Swollen Joints: limping
- Conjunctivitis + Scleral cysts
- Photophobia
- Respiratory problems: due to pinpoint-sized cysts lining the mucosa
Chronic Stage:
- Skin nodules may be seen on the legs, ears and back
- Skin thickening = “Elephant skin”
- Alopecia
- Hyperpigmentation
- Poor BCS
- Scleral Cysts
Where does Besnoitia Besnoiti reside in chronic infections?
- Dermis
- Subcutis
- Vestibulum of vagina
- Testis
- Muscle
How can Besnoitia Besnoiti be diagnosed?
- White nodules in scleral conjunctiva (even in sub-clinical cases)
- Histology of skin biopsy
- ELISA and IFA for antibodies in serum
- PM: looking for multifocal white pinpoint granular structures (tissue cysts) in the Upper Resp Tract
What is the treatment for Besnoitia Besnoiti?
NO treatment
- Sulfamides to decrease the severity of clinical signs
How can Besnoitia Besnoiti be prevented/ controlled?
- Test all new entries into herd
- Avoid sharing pastures
- Avoid natural mating
- Cull animals with clinical signs
- Bug repellents when animals kept indoors
What are the possible DDx to the Acute stage of Besnoitia Besnoiti?
- IBR
- Photosensitization
- Blue Tongue Virus
- Malignant Catarrhal Fever
- Mycoplasma bovis
What are the possible DDx to the Chronic stage of Besnoitia Besnoiti?
- Photosensitization
- Mange
- Ringworm
- Vitamin or Trace element deficiencies
How can Besnoitia Besnoiti be diagnosed?
- Clinical signs: tissue cysts on scleral conjunctiva and/ or vaginal mucosa + skin thickening
- Skin Biopsies
- Serology: ELISA
What are the types of photosensitization in cattle?
All of these lead to the presence of a photodynamic agent in the skin
- Primary: ingestion of St. Johns Wort, Bishops weed, or Tetracyclines
- Secondary: impairment of liver function causes an accumulation of chlorophyll depositing in the skin
- Tertiary: inherited altered pigment synthesis = Bovine Erythropoietic Protoporphyria, more commonly seen in Limousine cattle
- Idiopathic
What is the treatment for Photosensitization?
- Move indoors/ remove from direct sunlight
- Corticosteroids (NSAIDs if pregnant)
- Antibiotics if secondary infection: Amoxicillin LA
- Treatment for liver fluke if that is the offending cause on the liver
What is Anagen Defluxion and why does it happen?
Widespread loss of hair over the neck, trunk, limbs and head = Baldy Calf Syndrome
Typically this will follow an acute episode of systemic stress/ pyrexia, e.g. calf diarrhea, pneumonia, septicemia leading to extensive hair loss
What is the treatment for Anagen Defluxion?
- Treat the underlying cause of the stress/ fever
- Multivitamin injection may help too
A calf is born with raw ulcerated areas of skin, the skin generally is quite thin and easily damaged
What is this suggestive of and what can be done?
- Suggestive of Epitheliogenesis Imperfecta, which is an inherited condition
This condition is life threatening and most are euthanized
What are the most common causes of hives (urticaria) in cattle?
- Milk allergy: in the Channel island breeds
- Insect bites
- Certain drugs: pen-strep, oxytet, sulphas
- Plants
- Feeds (wheat, maize, soya and ricebean)
How can hives (urticaria) be treated/ managed in cattle?
- Avoidance of the offending cause, e.g. remove drugs, insects or move to a simple diet
- Dexamethasone 0.1 mg/kg, or oral prednisolone 1mg/kg
- Adrenaline in life-threatening angioedema
What is the most common etiological agent in cellulitis in cattle?
- Anaerobic bacteria (often it is Clostridium, in which case it is called malignant edema)
- The bacteria will enter the SQ due to a penetrating wound, and track along the fascial planes causing severe edema and necrotic tissue
What is the treatment of cellulitis in cattle?
- Open up the tissue to the atmosphere and remove necrotic muscle
- Provide parenteral penicillin or oxytetracycline
note: prognosis is guarded due to the poor response to antibiotics
Why does Actinomyces. bovis cause lumpy jaw in cattle?
- Localized lesions in the mouth due to scratches, shedding of teeth or coarse feed allow the bacterium to get into the jaw bone
- Causing Infection and inflammation of the bone (osteomyelitis)
Ergotism is caused by what fungus?
Claviceps purpurea
What is the pathophysiology behind ergotism?
- Ergot alkaloids in fungus contaminated feedstuffs are ingested
- Ergot alkaloids cause vasoconstriction and capillary endothelial damage
- Ischemic necrosis
- Gangrene
What is the treatment for Ergotism?
None
What are the subtypes of Bovine Papillomavirus, and where are they found on the bovine?
- Type 1: on the penis
- Type 2: most commonly on the head and neck (pedunculated)
- Type 3: anywhere on the body (non-pedunculated)
- Type 4: causes benign papillomas of the alimentary tract in cattle. In certain regions of Scotland, when cattle graze on bracken, these papillomas progress at a high rate to malignant carcinoma
- Type 5 + 6: small, found on the teats
How long does it take for bovine Papillomavirus warts to resolve?
Anywhere from 1-12 months
The animal does need a cell-mediated response, therefore immunosuppression will prevent resolution e.g. stress or BVD infection
How can Bovine Papillomavirus warts be treated or controlled?
- Large warts with a narrow stalk can be twisted and pulled: use local anesthetic, good restraint +/- sedation if needed
- Autogenous vaccines: fresh warts are harvested and sent to the lab for the production of a vaccine, then injected intradermal
- Cryotherapy, Cautery or Surgical removal: for warts near the eyes, penis or scrotum
How can you diagnose and treat a sheep with Cobalt deficiency?
- Measure MMA (methyl malonic acid) in the urine
- Measure Cobalt in the feed
- Inject with Vitamin B12 and see if there is a response to treatment
Treatment: Vit B12 injection
Seasonal Allergic Dermatitis is the same as _________ in horses
- Sweet Itch
It is a hypersensitivity to the Cullicoides midges +/- a secondary bacterial infection of the skin
How can Seasonal Allergic Dermatitis be treated/ prevented in sheep?
- Remove from pastures where midges are most prevalent
- Antibiotics for secondary bacterial infections
- Wash affected areas with diluent chlorhexidine
+/- steroids (unless pregnant) - The use of fly repellants
What are the Biting and Sucking Lice species that usually affect cattle?
Biting: Damalinia bovis
Sucking: Hematopinus spp + Ligognathus vituli
What are the clinical signs associated with a lice infestation in cattle?
- Itchiness!
- Over-grooming
- Alopecia
- Hairballs
- Anemia
Where on the cows body do the Sucking lice (Hematopinus spp + Ligognathus vituli) typically infest?
- Head, neck
Where on the cows body do the Biting lice (Damalinia bovis) typically infest?
- Back and rump
What is the term used to describe a lice infestation?
Pediculosis
What are the important mites that affect cattle?
Where on the cow do these mites preferentially infest?
- Sarcoptes scabei + Demodex bovis (burrowing mites) = ventral neck and chest and tail base
- Chorioptes bovis + Psoroptes ovis (non-burrowing mites) = shoulder, tail base and perineum
What are the blood-borne infectious agents which are transmitted by the Ixodes ricinus tick?
- Babesia divergens
- Louping ill virus
- Tick-borne fever = anaplasma phagocytophilum
How can ectoparasites be controlled/ treated in cattle?
1) Pour-Ons = Cypermethrin, Deltamethrin, Alphacypermethrin (All are zero milk withdrawal)
2) Washes = Amitraz
3) Avermectin Pour-On/ Injectable = good against sucking lice, not as good against biting lice. Psoroptes bovis and other mange need 2 treatments that are 10 days apart
What is the important lice in pigs?
Where on the body of the pig does this louse like to infest?
Hog louse = Hematopinus suis (sucking lice)
Found on the skin folds of the neck
What is the important mite in pigs?
Sarcoptes scabiei = scab mite
burrowing mite
What is the treatment for Sarcoptes scabiei in pigs?
1) Injectable avermectin
2) Wash/ Spray: Amitraz or deltamethrin
What is the important mite in sheep?
Psoroptes ovis
Where on the sheep does the Psoroptes ovis mite like to live quietly during the summer and early autumn months?
- Axilla
- Groin
- Infra-orbital fossa
- Inner surface of the auditory canal
How can Psoroptes ovis mite be treated/ controlled?
- Ivermectin injection: 2 injections 10 days apart (doesnt kill the eggs, so must kill the newly hatched mites)
- Short-acting Moxidectin: 2 injections, repeat after 10 days. Used in outbreaks
- Long-acting Moxidectin: prevents infection/ reinfection for 60 days
Note: injections have a long meat withdrawal of 37 - 104 days - Plunge Dipping sheep: Cypermethrin, Diazinon
Note: dipping have a meat withdrawal of 2 weeks - Premises should be left vacant for 1 month to allow all mites to die in the environment and prevent reinfection
