key: cord-0040500-j8clm7o9
authors: Thompson, Mark S.
title: Clinical Signs Approach to Differential Diagnosis
date: 2013-06-19
journal: Small Animal Medical Differential Diagnosis
DOI: 10.1016/b978-1-4557-4454-1.50005-8
sha: 6ca862d1dd43b0031ef295c2f6f95053377928a8
doc_id: 40500
cord_uid: j8clm7o9

nan

Obstruction (may appear similar to anuria/oliguria)

Fear: apprehension associated with the presence of an object, individual, or object; may be normal or abnormal, depending on context Phobia: quickly developed, immediate, profound abnormal response to a stimulus leading to catatonia or panic Unilateral disease: contralateral conscious proprioceptive deficits, mild gait disturbance Postictal paraparesis: transient in nature Paraparesis may be a side effect of anticonvulsant therapy (especially potassium bromide).

Hemiparesis or tetraparesis; lesions severe enough to cause paralysis usually result in respiratory arrest. Vestibular nuclei may be affected, causing vestibular ataxia, head tilt, and nystagmus; distinguish central vestibular disease from peripheral vestibular disease by presence of ipsilateral conscious proprioceptive deficits.

Edema (trauma, glaucoma, immune-mediated keratitis such as keratouveitis caused by canine adenovirus-1, endothelial dystrophy, neurotropic keratitis) Keratoconjunctivitis sicca Exposure keratitis Superficial keratitis (pannus) Corneal melanosis (entropion, ectropion, lagophthalmos, facial nerve paralysis) Cellular infiltrate (bacterial, viral, fungal) Dystrophies (lipid, genetic) Fibrosis (scar)

Fibrin (anterior uveitis: many causes) Hypopyon (immune-mediated, neoplastic [lymphosarcoma] , infectious [blastomycosis, cryptococcus, histoplasmosis, coccidioidomycosis, toxoplasmosis, FIP, protothecosis, brucellosis, septicemia]) Hyphema (trauma, blood-clotting deficiencies, ehrlichiosis, rickettsia, systemic hypertension, retinal detachment neoplasia) Lipid (hyperlipidemia with concurrent anterior uveitis to disrupt the blood-aqueous barrier)

Cataracts (genetic, metabolic/diabetic, nutritional, traumatic, toxic, retinal degeneration, hypocalcemia, electric shock, chronic uveitis, lens luxation)

Hemorrhage ( 

Postinflammatory-Mediators of inflammation (e.g., leukotrienes, thromboxanes) stimulate melanocytes to increase melanin production, which down regulates inflammation by scavenging free radicles. Examples of inflammatory conditions that lead to increased melanin production include allergies, Malassezia dermatitis, bacterial pyoderma, dermatophytosis, demodecosis, scabies, and actinic and intertrigo dermatitis. Inflammation affecting hair follicles may lead to melanotrichia (e.g., sebaceous adenitis, panniculitis, vaccine reactions). Endocrine-hyperadrenocorticism, hypoadrenocorticism, hypothyroidism, hyperestrogenism, and other sex hormone imbalances may result in diffuse hyperpigmentation. Papillomavirus associated-Pugs may be at risk for development of papillomavirus-associated, slightly raised, scaly, hyperpigmented macules and plaques in their groin region, abdomen, ventral thorax, and neck. Similar lesions are described in miniature Schnauzers, American Staffordshire terriers, and Pomeranians. May transform to squamous cell carcinoma. Pigmented tumors-apocrine cysts are bluish, cutaneous hemangiomas and hemangiosarcomas appear red, dark purple, or bluish-black. Melanomas, melanocytomas, and basal cell tumors are frequently black. Squamous cell carcinomas, trichoblastomas, and fibromas also may be dark brown to black.

Exogenous pyrogens (infectious agents and their products, inflammation or necrosis of tissue, immune complexes, pharmacologic agents, bile acids) Endogenous pyrogens (fever-producing cytokines)

Sustained exercise Seizure disorders (especially prolonged or cluster seizures) Hypocalcemic tetany (eclampsia)

Lesions in or around anterior hypothalamus Hypermetabolic disorders Hyperthyroidism Pheochromocytoma Malignant hyperthermia Halothane Succinylcholine

Due to melanocyte destruction, dysfunction, or abnormal distribution of melanosomes.

Albinism-hereditary absence of pigment Piebaldism-presence of white spots where melanocytes are absent Waardenburg-Klein syndrome-affected animals have absence of melanocytes in areas of skin and hair, blue or heterochromatic eyes, and are also deaf. Reported in cats, bull terriers, Sealyham terriers, collies, Dalmatians Canine cyclic hematopoiesis-lethal autosomal recessive disease of collies. Gray coat, light-colored nose, cyclic episodes of neutropenia every 12-14 days resulting in sepsis and amyloidosis Chédiak-Higashi syndrome-rare autosomal recessive disease of blue smoke Persian cats. Partial oculocutaneous albinism with abnormal function of granulocytes and platelets resulting in hemorrhage, recurrent infections, and death at a young age. Graying-age-associated, reduction of melanocyte replication. Vitiligo-macular leukoderma and leukotrichia of nose, ears, buccal mucosa, and facial skin. Antimelanocyte antibodies found in serum of some affected dogs. Seen most commonly in Siamese cat, Belgian Tervuren, German Shepherd, collie, Rottweiler, Doberman Pinscher, Giant Schnauzer. Nasal hypopigmentation-season-associated lightening of nasal planum during winter months most common in Siberian Husky, Golden Retriever, Labrador Retriever, and Bernese Mountain Dog. Seen also in many other breeds.

Postinflammatory-Discoid lupus erythematosus is the most common cause of postinflammatory nasal depigmentation. Also pemphigus complex, SLE, uveodermatologic syndrome, bullous pemphigoid, mucocutaneous pyoderma, drug eruption, and contact dermatitis. Infectious causes include leishmaniasis, blastomycosis, sporotrichosis, and bacterial folliculitis. Drug related-ketoconazole, procainamide, and vitamin E may cause diffuse coat lightening.

Nutritional/metabolic-deficiencies of zinc, pyridoxine, pantothenic acid, and lysine are associated with graying of hair. Dark hairs may become reddish in color with copper deficiency, hypothyroidism, hyperadrenocorticism, hyperestrogenism, hyperprogesteronism, chlorine exposure, and chronic exposure to ultraviolet light. Neoplasia associated-nasal depigmentation, leukoderma, and leukotrichia sometimes seen with epitheliotropic T cell lymphoma, basal cell tumors, mammary adenocarcinoma, and gastric carcinomas. Idiopathic-leukotrichia and patchy hypopigmentation reported as idiopathic in Labrador Retrievers, and black Newfoundlands. Siamese cats may be affected with periocular leukotrichia, which may be associated with upper respiratory tract infections, pregnancy, dietary deficiencies, or systemic illness. 

Snoring or snorting associated with partial nasal or nasopharyngeal obstruction. 

Vasogenic (brain masses that lead to breakdown of bloodbrain barrier) Cytotoxic (hypoxia, neuroglycopenia) Interstitial (hydrocephalus) 

See Cachexia and Muscle Wasting.

Feline leukemia virus (FeLV)

Endocrine (mild anemia associated with hypoadrenocorticism, hypothyroidism)

Myeloaplasia/aplastic anemia (FeLV infection, ehrlichiosis, trimethoprim-sulfa, estrogen toxicity, phenylbutazone, chemotherapy, chloramphenicol)

• Bacterial pyoderma (papules and pustules) • Demodicosis (papules and pustules

• Dermatophytosis (rare papules, uncommon pustules) • Sarcoptes mange (papules