Environmental Flashcards
What is often referred to as the sunburn or erythema spectrum and s about 1000 times more erythemogenic that UVA?
UVB (290-320)
What penetrates deeper into the skin that UVB and is the spectrum associated with photosensitivity reactions?
UVA (320-400)
What is the wavelength range most damaging to skin?
320-340
What light is partially reflected, absorbed, and transmitted inward?
UVL
Absorbed light raised the energy level of light-absorbing molecules called what? This results in various biochemical processes that can damage visually any component of a cell. This damage can result in cellular hyperporliferation, mutagenesis, alteration of cell surface markers and toxicity.
Chromophores
Chromophores in the skin include keratin proteins, blood, hemoglobin, porphyrin, carton, nuncelric acids,melanin, lipoproteins, peptide bonds and aromatic amino acids such as tyrosine, tryptophan and histidine.
List the aromatic amino acids
tyrosine, tryptophan and histidine.
What are natural barriers of UVL damage?
SC, melanin, blood and carotenes
_________ is the classic sunburn reaction and is dose-related response to light exposure. ________ occurs when the skin has increased susceptibility to the damage effect of UVL because of the production, infection, injection, or contact with a photodynamic agent.
Phototoxicity
Photosensitivity (UVL light)
What type a dermatitis occurs from actinic reaction on white or light skin? The condition develops when skin is exposed to direct or reflected sunshine
Solar dermatitis
For every 300m increased in elevation, the suns intensity increased by __%.
4%
What may be particularly important in the pathogenesis of solar damage. These substances deplete antioxidants, recruit neutrophils and destroy and degrade all components of connective tissue?
Oxygen intermediates - superoxide radial and hydrogen peroxide
Describe the biphasic apoptosis that occurs in solar damage?
Some apoptotic keratinocytes are seen within 4 hours of exposure due to OVAs direct damaging effect on the cell membrane. Other apoptotic cells appear about 24 hours after exposure. This delayed damage is a result of DNA alteration.
What is an actinic reaction in poorly pigmented nasal skin of dogs. The affect dogs may be born without pigment, or the nose may have undergone spontaneous noninflammatory depigmentation.
Canine Solar Dermatitis
What breed is predisposed to developing solar dermatitis?
The Australian shepherds appear to be an increased risk.
Found principally at the junction between the haired and non haired skin of nose.
What is the histologic description of solar dermatitis?
The early depigmentareas of the nose show fewer melanocytes and less melanin pigment than are seen in normal skin. After exposure to solar radiation, epidermal hyperplasia with intraepidermal edema is observed. Vacuolated (sun burn cells) and apoptotic keratinocytes are seen.
Solar elastosis is usually NOT seen and requires special stains (PAS)
What is a chronic actinic dermatitis of white ears and occasionally the eyelids, nose and lips of cats?
Feline Solar Dermatitis
In Feline Solar dermatitis, actinic damage to the ear tips occurs from repeated exposure to what type of light?
UVB light.
What has been administered orally to cats with solar dermatitis and seen some success?
B-carotene and canthaxanthin
What is Plesiotherapy?
modality in which a source of ionizing radiation is placed in contact with the exterior surface of the body
What is brachytherapy?
It is a form of radiation therapy where a sealed radiation source is placed inside or next to the area requiring treatment
What breeds are predisposed to truncal solar dermatitis?
Dalmatian, American Staffordshire terrier, German shorthaired pointers, white boxers, whippets, beagles and white bull terriers.
Other than SCC, skin with solar damage are more likely to develop what other neoplastic processes? ( there are two)
hemangioma and hemangiosarcoma
Unlike solar dermatitis, lesions of photosensitivity occur in ___ regions of the body. This hairs must be light in color.
well-haired
UVB susceptibility is mediated almost exclusively by what inflammatory molecule?
TNFa
Black skin absorbs nearly ___% more solar radiation than white skin, and intense solar exposure can cause thermal burns in darkly pigmented animals.
50%
What does is mean when keratinocytes appear to be “standing at attention” on histopathology
This is seen only in electric burns which reveals a feature of elongated degeneration cytoplasmic processes that protrudes from the lower end of the detached basal cells into the space separating the dermis. The nuclei of the basal cells and otters of the higher lying epidermal cells appear stretched in the same direction as the fringe of cytoplasmic processes.
What is a subtle but characteristic finding in radiant heat burn histopathology?
wavy eosinophilic elastin fibers in the superficial dermis
Digital and pedal sloughs have been recognized in cats with what two diseases? Dogs?
Bronchogenic carcinoma or follicular lymphoma
Digital sloughs have been reported in dogs with hepatitis
Puppies and kittens will slough digits when fed highly concentrated evaporated milk.
What are the two subfamilies of venomous snakes that are indigenous to the US?
Crotaludae - “pit vipers” - copperhead, cottonmouth and rattle snakes
Elapidae- coral snakes in the south.
Necrosis is much more common with pit viper bites than with coral snakes.
For maximum benefit, how quickly should antivenin be administered?
Within 4 hours
**Tetanus should also be administered
What two organisms are part of the oral flora of snake bites?
PSA and clostridium
What are the two most common causes of plant foreign bodies in dogs?
Foxtail (Hordeum jubatum) - external ear canal
Burdock (Arctium spp) - oral ulcerations
What is a vascular abnormality defined as a feint communication between an adjacent artery and a vein that bypasses the capillary circulation?
Ateriovenous fistula
Most are acquired and a result of blunt trauma and most common area are the paws and neck.
What is a rare granulamtaous reaction thought to be due to the interaction of ointments, antibiotics, endogenous fat or oily contents of cysts with erythrocytes? It is associated with smalls alike structures (parent bodies) filled with endobodies (spherules) and has been reported in humans and dogs.
Myospherulosis
Stain with diaminobenzidine (endogenous peroxidase) indicating that spherules are erythrocytes
What is a rodenticide and roach pain in the US that was banned more that 35 years ago because of its toxicity? This substance moves with potassium through cell walls.
Thallium
What test is used to determine a thallium toxicity?
Gabriel Dubin test
Atomic absorption spectrophotometry.
Why are chelators not recommended in thallium toxicity?
It can draw thallium out of the tissue into the blood stream reacting a rebound effect.
What are normal protective responses to pressure-induced ischemia and inflammation?
Callus
Callus dermatitis is most common in what breeds?
Great Danes, Saint Bernards, Newfies and Irish Wolfhounds
What breed is ventral comedones syndrome most commonly seen in?
Greyhounds
Posttraumatic alopecia has been recognized in a small number of ___ and it thought to be associated with blunt force trauma to the cats body.
cats
Rump fold intertrigo is seen in what breed of cat?
Manx
