This document discusses dermatology and skin diseases. It covers the structure and functions of skin, common causes of skin diseases including infectious (viral, bacterial, mycotic, parasitic) and non-infectious causes. It describes common skin lesions and diseases such as dermatitis. Dermatitis is inflammation of the skin that can be caused by bacteria, fungi, parasites, chemicals, allergies or other sources. Symptoms include redness, swelling, blisters and itching. Treatment involves identifying and removing the cause, using antibiotics for bacterial infections, anti-fungals, anti-parasitics or anti-allergy medications as needed.

1. Dermatology
(Skin Diseases)
Karima Al Salihi

2. Dermatology (Skin Diseases)
• The skin is a covering for the whole
body so it is a mirror that reflects
many systemic and local diseases.
• The incidence of skin diseases in
animals is high.
• Many of the skin diseases are
contagious therefore quick and
accurate diagnosis is important in
their control and eradication.

3. Function o f the skin
(1) Protection from light, organisms and
mechanical.
(2) Immunologic function.
(3) Vitamin D synthesis.
(4) Heat regulation.
(5) Secretary organ by sweating : e.g. wastes,
urea.
(6 ) Water reserve.
(7) Sensory organs.
(8 ) Reflection of internal feelings

4. Causes o f skin diseases:
[1] Infectious:
(1) Viral:
1) Contagious erythema.
2) Ulcerative dermatitis in sheep.
3) Lumpy skin diseases (in cattle).
4) Pox.
5) Vesicular papular dermatitis (in
horse).

5. (2) Bacterial:
1) Bacterial dermatitis. 2)
Tuberculosis. 3) Foot rot.
(3) Mycotic:
1) Ring worm.
2) Epizootic lymphangitis.
3) Spirocheta.
(4) Parasitic:
1) Protozoa e.g.
Leishmaniasis.
2) Arthropodes as mange.
3) Helminthes as filariasis.

6. [2] Non infectious:
(1) Nutritional deficiency of zinc, cobalt,
iodine and copper.
(2 ) Chemical injury as acids, alkalies and
gases.
(3) Histamine production: urticaria.
(4) Lesions due to severe abrasion or
friction.
(5) Disturbance in circulation such as
erythema.
(6 ) Distribution in nervous tissue “itching”.

7. (7) Internal diseases (constipation, nephritis).
(8 ) Neoplasms (wastes, papilloma,
carcinoma).
(9) Congenital defects (alopecia).
(10) Over feeding of carbohydrate without
enough exercise.
(11) Traumatic (wounds).
(12) Thermal, excessive heat, sun rays.
(13) Long administration of some drugs as
arsenic, mercury, serum causing skin rashes.
(14) Endocrine disorders.

8. Scientific Term used in Skin
Diseases
[1] Primary lesions (less than 1 cm
in size):
(1) Macule: It is a flat circumscribed discoloration o f
the skin or mucous membrane.
(2) Papule: A solid elevation of the skin or mucous
membrane extending deeper in the epidermis.
(3) Nodule: A solid elevation of the skin or mucous
membrane extending into the dermis (neoplastic or
inflammatory).
(4) Vesicle: A fluid filled superficial circumscribed
elevation of skin or mucous membrane.

10. [2] Lesions more than 1 ml: Such as
cyst, tumor, granuloma, plaque.
[3] Primary lesions of varying sizes:
(1)Pustule: Vesicle of the skin or
mucous membrane which contain pus.
(2)Wheal: An irregularly shaped,
elevated transient lesion of the skin or
mucous membrane due to edema.

12. [4] Secondary cutaneous lesions:
(1) Erosion: Shallow ulcer of the epidermis
doesn’t penetrate the entire epidermis.
(2) Erythema: A redness of skin due to
capillary congestion.
(3) Hyperkeratosis: An increased thickening
of the keratin layer of the epidermis (normal in
the foot pads, nose of dog and cat).
(4) Scab or crust: A collected dried exudate
on the surface of the epidermis adherent to
hairs.

14. (5) Scale: A collection of excessive
keratin flacks upon the surface o f the
skin.
(6) Scar: A permenant depigmented area
o f fibrous tissue without hair growth.
(7) Parakeratosis: Retention of nuclei in
the keratin layer (stratum comium) with
absence of stratum granulosum
characterized by scale formation.
(8) Seborrhea: Over active disease of
sebaceous glands result in oilness, crust
or scales.

18. Principle s of treatment of skin diseases:( 1)
Accurate diagnosis of the cause to choose the correct
topical or systemic treatment by obtaining complete
medical history and through medical examination.
(2) Removal of hair coat and debris to enable
topical application to come into contact with the
causative agent.
(3) In allergic diseases remove the causative
agent.
(4) In bacterial disease, sensitivity tests on
culture of the organism are advisable

19. (5) Treat the primary cause and prevent
secondary infection by:
1) Base of bacteriostatic ointment or dressing.
2) Administration of local anaesthetic
ointments to prevent further damage from
scratching.
3) Fluid therapy in case of fluid and
electrolytes losses.
4) Sulpher containing amino acids or zinc or
vitamin A facilitate the repair of skin tissues.

20. Drugs used for Treatment of Skin Diseases:
(1) Stimulants:
!These are compounds which have an action on the skin.
!They are powders, aqueous sol., suspensions or mineral oils.
!They applied externally on the skin lesion.
(2) Sedatives: They used to depress irritation and it may be:
1) Emollients:
1- Oils: such as olive, caster, cotton seed oil.
2- Fats: such as wool fat.
3- Wax: such as bees wax.
4- Hydrocarbon: as liquid paraffin, cod-liver oil and glycerin.
2) Sedative powders: As chalk, talk, zinc carbonate and kaolin.
(3) Astringent:
It coagulates protein forming a protective layer. Such as copper sulphate, zinc
sulphate and ferric chloride.
(4) Corticosteroid:
They inhibits fibroblasts and diminish the fibrosis of chronic inflammation, inhibit
vasodilatation and increase permeability and exudate formation of acute
inflammation.

21. (5) Counter irritant:
They are substances which applied to the skin to cause
local irritation and inflammation, e.g. iodine.
(6) Caustics:
They are agents which destroy tissue and excessive
granulation and superficial tumors (warts), ex.: Nitric acid,
caustic soda, phenol, mercury chloride.

22. (I) Diseases of the Epidermis
and Dermis
They include Dermatitis, Eczema,
Urticaria, Photosensitization, Pityriasis,
Parakeratosis and Hyperkeratosis.
•Dermatitis
•Definition:
•It is inflammation of the dermis and epidermis.
•Causes:
•(1) In all species:
•1) Mycotic dermatitis due to Dermatophilus congolensis in horses, cattle
and sheep.
•2) Staphylococcus aureus.
3) Ring worm.

23. 4) Photosensitive dermatitis.
5) Chemical irritation (contact dermatitis)
topically.
6) Arsenic and systemic poisoning.
7) Mange mite infestation.
8 ) Biting flies.
9) Stephanofilaria sp. dermatitis.
10) Strongyloids sp. dermatitis.

24. (2) In cattle:
1) Udder impetigo
(staphylococcus
aureus).
2) Cow pox.
3) Lumpy skin disease,
Foot and Mouth
disease, Rinder pest,
Bovine virus diarrhea.

25. (3) In sheep and goat:
1) Sheep pox.
2) Ulcerative dermatitis.
3) Fleece rot.
4) Ovine dermatitis.
5) Caprine idiopathic dermatitis.
(4 ) In horses:
1) Horse pox.
2) Canadian horse pox.
3) Viscular stomatitis.
4) Dermatophytes including ringworm.
Pathogenesis:
(1) Inflammation of deeper layers of the skin involving blood
vessels and lymphatics.
(2) It may be acute, chronic, suppurative, weeping ulcerative or
gangrenous.
(3) Increased thickness, temperature, pain and itching.

27. Clinical findings:
(1) Symptoms start by erythema,
vesicles.
(2) Edema of the skin and
subcutaneous tissues.
(3) Healing stage or scab formation or
may be necrosis or gangrene of the
affected area in severe cases.
(4) Systemic reaction may occur when
the affected skin area is extensive.

28. (5 ) Spread o f infection to subcutaneous may result in
diffuse cellulitis. *
(6) Shock with peripheral circulatory failure may be present
in the early stages.
(7) Toxemia due to absorption of tissue breakdown.
Clinical pathology and diagnosis:
(1) Skin scraping or swabs for parasites or bacterial
examination.
(2) Cellular and sensitivity tests for bacteria.
(3) In allergic or parasitic states, accumulation of
eosinophils in the inflammed area.

29. •Treatment:
(1) Hygienic treatment:
1) Remove the injuries and harmful stimuli.
2) Remove the physical or chemical agent from
environment.
3) Supply balanced diet to repair nutritional deficiency (vit.
A, B, E, and D).
(2) Medical treatment:
•In infectious causes, identify the causative agent, make
sensitivity test (in bacterial infection) to select the specific
antibacterial drug. E.g. garamycin, terramycin ointement
applied on the skin lesion.

30. (2) Systemic:
1)Antihistaminic: It is recommended when tissue
destruction is extensive or the dermatitis is allergic in
origin.
2)2) Calcium preparations
3) Fluid therapy: If shock is present.
4) Parental antibiotic and anti-fungal agents:
5) Anaesthetic drugs:
•NB: If the lesions are extensive or secondary bacterial
invasion is likely to occur, parental antibiotic or antifungal
agents may be preferred to topical application.
NB: The use of vaccination as prophylaxis in viral and
bacterial dermatitis must not be neglected. Autogenous
vaccines may be most satisfactory in bacterial infections.