Things You'll Need
- Magnifying glass
- Surgical gloves
- Damp cloth
- Hypo-allergenic dog food
Instructions
Visual Inspection
Roll the dog over gently and using the magnifying glass, eliminate the most easily identified diagnosis: parasites. Check for visible fleas or flea feces--small black specks that if moistened with the damp cloth show red due to the blood content. Look for thinning hair around the tail base--another indicator for fleas. Search for "walking dandruff"---visibly moving skin flakes---these indicate parasitic mites, which are also visible if you search closely.
Wear gloves and examine skin closely, studying lesions: reddened circles indicate ringworm; symmetrical hair loss with darkened crusty skin, alopecia X (black skin disease). Oozing sores suggest systemic fungal infection but this should be confirmed by laboratory tests---other symptoms including weight loss and breathing difficulties are usually present with this diagnosis. Use the back of your hand to test temperature of bald spots: inflamed "hot spots" indicate allergy.
Smell scaly skin--odor indicates yeast infection. Non-odorous patches grouped in clumps are typical of mange, caused by mites.
Put on gloves to examine and gently palpate any lumps--small lumps on the muzzle are usually warts; localized masses of itchy lumps, hives, indicating allergy. Larger lumps containing white paste are sebaceous cysts, caused by blocked sebaceous glands; lumps that ooze pus are abscesses. Lumps that you cannot explain by this visual inspection must be monitored--changes or enlargement can indicate melanoma; a biopsy may be necessary.
Background Factors
Check whether the dog has been in contact with scabies, ringworm or other contagious conditions.
Inquire into the animal's parentage. Alopecia X is more likely in poodles, malamutes and Pomeranians, but similar hair loss in Dobermans, Great Danes, dachshunds, or retrievers indicates hypothyroidism. Spaniels, German shepherds and pointers are unlikely to have allergies; dalmatians and terriers are susceptible to them. Lumps on Labradors, Dobermans and schnauzers are likely to be harmless fatty deposits called lipomas.
Check whether sores are year-round or seasonal. Allergies to fleas, pollen or fertilizers and lawn dressings are likely diagnoses for seasonal itching. Sores that begin on the face and worsen in the sun indicate immune disease.
Investigate diet and appetite. Food allergies cause sores, itchy feet and hair loss. In older dogs, hair loss accompanied by an increasingly ravenous appetite and heightened thirst indicates Cushing's syndrome---malfunction of the pituitary or adrenal glands.
Testing
Introduce hypo-allergenic food or a food elimination diet for 12 weeks. Improvement followed by itching on return to original diet confirms food allergy.
Consult a canine dermatologist for allergy testing if your observation, questioning and food eliminations cannot identify a cause for hives or hot spots.
Request laboratory testing for hypothyroidism, adrenal deficiency, lupus and immune disease if allergic or parasitic causes are not found.