Dermatology

Hypothyroidism results in decreased production of the thyroid hormones thyroxine (T4) and triiodothyronine (T3) from the thyroid gland. At least 95% of cases of canine hypothyroidism are believed to be due to acquired primary hypothyroidism. Destruction of the thyroid gland can result from lymphocytic thyroiditis, idiopathic thyroid atrophy, or rarely neoplastic invasion.

Malassezia is a genus of lipophilic yeast found as a commensal of the skin and mucosal surfaces that may cause skin disease in a variety of mammalian species. In normal dogs these organisms are present in very small numbers on the skin (fold areas-lip, vulvar, axillae, interdigital), oral and anal mucosal surfaces, in the ear canals and anal sacs. In contrast to Candida, MD is not associated w/recent antibiotic administration, in fact, there appears to be a symbiotic relationship between the surface staphylococcal organisms and the yeast.

Fleas are still the most common cause for parasite induced pruritic skin problems in many geographical regions. Since the nineteen's many different drugs and preventative have been introduced to prevent and to treat flea infestation, and certainly the occurrence of severe widespread infestations have declined. However, the lack of pet owner compliance and neglect of addressing environmental flea ainfestation are probably the most common causes for a chronic recurring flea problem.

Skin and ear problems are very common reasons for dogs and cats being presented to a veterinarian. These animals can suffer from many different skin diseases with a wide range of underlying causes. Because the skin has a limited range to react to the different insults a straight-forward diagnosis is commonly not possible, especially in patients with chronic skin diseases.

Approximately 80 to 85% of cases of hyperadrenocorticism in dogs are due to pituitary dependent hyperadrenocorticism (PDH), with the remainder due to an adrenocortical tumor (AT). Cortisol is the most common secretory product of the adrenal gland in hyperadrenocorticism.

The diagnosis of ANY skin disease is based on detailed history taking, clinical findings (identification of primary lesions, distribution of lesions), laboratory testing and therapeutic trials. For autoimmune skin diseases (AISD) the most beneficial laboratory procedure is histopathologic evaluation.

In order to understand when and how to culture, it may be useful to first understand a bit about the etiology and pathophysiology regarding pyoderma:

Diabetes mellitus (DM) is a common endocrine disease in dogs and cats characterized by an absolute or relative deficiency of insulin. This results in a decreased ability of cells to take up and utilize not only glucose, but also amino acids, fatty acids, and electrolytes. In addition the lack of insulin results in increased gluconeogenesis, glycogenolysis, lipolysis, ketogenesis, and protein catabolism.

Alopecia in the dog is a common clinical finding. It is most commonly associated with pruritus due to allergic skin disease. There are also many causes of nonpruritic alopecia. Since the skin and hair can only "react" in a limited manner regardless of the triggering event, signalment, history (hx), physical exam (PE) and laboratory testing (eg skin scrapings, skin biopsies, fungal cultures, endocrine testing, intradermal testing, etc) all may be needed to help determine the underlying cause.

Non-responsive or chronic and recurrent otitis externa is a common reason for pet owners to leave their regular veterinarian and seek second (and third, fourth and fifth........) opinions. Proper management of these conditions takes a co-ordinated approach that includes strong history taking skills (keeping in mind the primary, predisposing and perpetuating factors involved in otitis), a thorough physical and otoscopic evaluation, appropriate diagnostic tests and the institution of a sound therapeutic plan that addresses the underlying factors while treating the current condition.

Skin disease is the second most common reason for a pet to be presented to a family veterinarian (Hill, 2006). The most common reason is preventive care! Pruritus is the most common dermatological presenting complaint along with "I need to stop that disgusting licking noise that my dog does at night!"

Once we have ruled out the possibility of parasites and treated a secondary microbial dermatitis, our history taking skills and physical examination will often point to an allergic etiology as the cause of the pruritus. In the non-seasonal dog, rule outs will include an adverse food reaction and environmental allergy.

Hypoadrenocorticism (Addison's disease) results from failure of the adrenal glands to secrete glucocorticoids and mineralocorticoids. Most cases of hypoadrenocorticism are due to primary adrenal failure, resulting in deficiency of usually both cortisol and aldosterone from the adrenal cortex.

The owner of this retriever first noticed the golf-ball-sized mass three days before presentation.

Use skin cytology to diagnose Malassezia dermatitis.

What's causing this cat's pruritic generalized crusting dermatitis?

Specific steps you can take to help affected dogs.

Read this report of the successful treatment of two dogs.

Self-traumatizing disorders can occasionally start as a behavioral pathology.

Thomas P. Lewis II, DVM, DACVD, discusses the possible concerns of this drug combination on the liver.

What are the dermatologic effects of steroids?

Use this information to successfully answer clients' questions about their pets' dermatology issues.

Eosinophilic granuloma complex is a dermatologic condition most commonly seen in cats. Allergies such as food allergy, atopy and insect hypersensitivities have been associated with this syndrome. If the allergic cause for this dermatitis is not found than the EGC is described as being idiopathic.

Feline alopecia is a common dermatologic presentation because of the overt clinical findings observed by the owner. Alopecia can broadly be categorized into traumatic induced, hair follicle/shaft damage, and hair cycle abnormalities.

Bacterial skin infections represent a common condition affecting the canine and is often recurrent. The infective organism most frequently isolated is Staphylococcus intermedius although other species of staphylococcus may be involved.

The hypothyroid patient can present with countless symptoms, all related to the underlying cause. As is the case with allergic dermatitis, these patients are typically pruritic, however the pruritus in these situations is due to secondary bacterial and yeast infections, not an allergic disorder.

Cutaneous or subcutaneous nodules are relatively common problems in the dog and cat with assorted etiologies to be considered. The diagnostic pursuit is often critical to attaining a definitive diagnosis for optimal clinical management.

Some of the most common canine cutaneous tumors include: histiocytoma, mast cell tumor, and the adnexal tumors. Cutaneous T-cell lymphoma (mycosis fungoides) is a pruritic neoplasia of older dogs with a poor prognosis.

Much has changed in the management of bacterial skin diseases in veterinary patients since the recognition of methicillin resistant (?-lactam antibiotic resistant) staphylococcal skin infections and their significance in both the human and veterinary medical communities. Awareness and responsible use of antibiotic medications is a must when dealing with these emerging pathogens.

Draining tracts or fistulous tracts are tract lesions that connect with a central area or focus of inflammation to the skin's surface. Draining tracts are most commonly associated with nodules which are large (greater than 0.5 cm), firm, raised usually circular lesions that extend down into the dermis.