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Etiology

Canine dermatophytosis (canine ring worm) is a relatively common dermatological condition caused by Microsporum canis, Trichophyton mentagrophytes and Microsporum gypseum. These fungi are keratinophilic in nature. It can occur mostly in the face and forelegs.

Ulcerative dermatitis is one of the primary features of the skin disease in which discontinuity of the skin along with marked inflammation and necrosis are seen.

Scales are having imperfectly keratinized superficial layers of the epidermis characterized by cracks or thin flakes.

Crust is characterized by the presence of desquamated squamous epithelial cells. The dried exudate consists of necrotic cell debris, leucocytes, RBC’s, plasma proteins and microorganisms. It is classified into serous crust (eosinophilic protein exudates), hemorrhagic crust (RBC’s), cellular crust (degenerative leucocytes mainly neutrophils), serocellular crust (mixture of serum or plasma or leucocytes) and palisadic crust (presence of leucocytic infiltration, pustules and parakeratosis organized in a horizontal manner).

Etiology

Demodecosis is caused by Demodex species follicular mite with increased numbers. But, it is generally caused by Demodex canis. It is divided into two forms – juvenile and adult forms. The juvenile form is more common. This condition may be localized or generalized in nature.

It is characterized by irregular growth and development of hair follicles and associated glands.

The disease is characterized by irregular growth and development of hair follicles and associated glands.

Sebaceous gland hyperplasia: It is a rare disease of dogs characterized by high hair coat and underlying skin, greasiness and in mainly due to excessive greasiness followed by clumping of the hair coat.

Etiology

Pemphigus foliaceous is a bullous autoimmune skin disease of canines affect ing epidermis and hair follicles. The recorded targeted auto-antigen in canine pemphigus foliaceous is desmoglein 1 (Dsg 1). This auto-antibody binds to Dsg 1 which is a prominent component of desmosome in the superficial layer of epidermis and hair follicle. It may be due to loss of intercellular cohesion leading to acantholysis followed by formation of superficial vesicles and bul lae. The common sites for the development of pemphigus in dogs are dorsal lateral muzzle, temporal, planum nasale, pinnae, periorbital skin and paw pads.

The condition is one of the most common pruritic skin disease caused by hypersensitivity reaction to the flea salivary antigens. Type I immediate hypersensitivity, type II delayed hypersensitivity and cutaneous basophil hypersensitivity to the flea salivary antigens have been recorded. Late phase IgG mediated reaction also caused in this condition. It occurs in dogs mostly between 1 and 3 years of age.

Synonym – Cutaneous ancylostomiasis

Etiology

Hook worm dermatitis is uncommon or rare skin disease due to larval migration of the normal life cycle of Ancylostoma braziliensis and Ancylostoma caninum. It is mainly due to hypersensitive reactions against migrating third stage larvae in the distal extremities.

Etiology

The condition is characterized by formation of granuloma to pyogranulomatous dermatitis with paniculitis. The causative organism is normally present in the macrophage which may be Mycobacterium tuberculosis, M? bovis and M? microti.

Etiology

The condition is usually caused by implantation of low virulent saprophytic bacteria due to traumatic injury. These organisms stimulate cell mediated immune response by persistence of antigen in the tissue.

Etiology

It is caused by Staphylococci spp- characterized by superficial pyoderma in dogs. It is mainly due to exfoliative toxins of S? aureus.

Gross pathology

The lesion reveals cutaneous exfoliation, vesicles, pustules (Figure 6) and crust.

Etiology

Superficial pyoderma usually occurs in the epidermis and upper infundibulum of the hair follicle. It usually heals without scar formation and commonly caused by Gram positive cocci Staphylococcus spp., particularly exfoliative toxin of this species.

Etiology

Atopic dermatitis is genetically predisposed to allergic skin disease. It consists of atopy and hereditary cause to produce IgE mediated allergic reaction to environmental allergens.

Immunohistochemistry reveals the presence of Langerhans cell proliferation and strong positive expression of IgE in skin tissue sections.

Gross pathology

Etiology

 Acral lick dermatitis is usually observed on extremities of dogs and the probable etiology is persistent licking. It is also caused due to self-trauma or mutilation.

1. Calibration of Milk Butyrometer

Introduction

Butyrometer is used for determination of fat for milk and milk products by Gerber method. The milk butyrometer is a graduated vessel, which are designed in such a way that the internal volume of each unit is 0.125 ml which is corresponding to 1 percent fat. Sometimes due to manufacturer’s error, the volume of one unit of milk butyrometer is not exactly equal to 0.125 which leads to subsequent error in results in milk fat. So before starting to use a new butyrometer, it is essential to calibrate for its efficiency in the laboratory. Mercury is used to calibrate milk butyrometer.

Apparatus

Milk butyrometer (0 – 10% graduation), analytical balance

1. Preparation of Standard Sodium Hydroxide Solution

 Introduction

 When oxalic acid reacts sodium hydroxide, sodium oxalate and water are

form. Phenolphthalein indicator detects the end point by its characteristics

colour change.

 Apparatus

 Burettes, pipette, volumetric flask, beaker

 Reagents

 • Oxalic acid crystals

 • Sodium hydroxide – 0.1 N approximate

 • Phenolphthalein solution – 0.1 percent in ethyl alcohol

Procedure Preparation of 0.1 N oxalic acid solution 1. Weight accurately 1.575 g of oxalic acid into a 250 ml beaker using a weighing bottle. 2. Add some distilled water to the beaker and dissolve the oxalic acid with the help of glass rod. 3. Transfer the solution into a 250 ml volumetric flask through a funnel. 4. Wash the beaker 3- 4 times with small quantities of distilled water and transfer the washing into the flask. 5. Make up the volume up to the mark with distilled water and mix thoroughly. 6. Preparation of approximately 0.1 N sodium hydroxide solution 7. Weigh about 4.25 g of sodium hydroxide pellets and dissolve into 200 ml of distilled water.

1 Detection of Starch Introduction

Starch is widely available in several forms such as wheat flour, corn flour and commercially manufactured starch. It is extensively used by adulterators to raise the SNF content in the milk. When high amounts of starch are added to milk, it can cause diarrhea due to the indigestion of starch in colon. Apart from this, accumulation of starch in the body may prove very fatal for diabetic patients. In this method, starch in milk can be detected by using iodine solution. Iodine from the iodine solution gets absorbed on the starch molecule surface and resultant product of adsorption has deep blue colour.

Reagents

 • Potassium iodide

 • Iodine solution - 1% (Add 1 g of iodine and 5 g of potassium iodide in

distilled water and dilute to 100 ml)

Sample Preparation

Sample should be taken at six or more points on the top of the surface by means of a tubular trier of sufficient length to extend to the bottom of the barrel. Remove this cores and transfer to clean, dry, air tight container and seal immediately.

Before opening sample for analysis, make homogenous either by shaking or by alternately rolling and inverting container. If lump are present, sift sample through No 20 sieve, rubbing material through sieve and tapping vigorously, if necessary.

Avoid sampling on rainy day or when humidity is high, so as to reduce moisture absorption from air.

1 Determination of Moisture Content by Moisture Balance Introduction

In this procedure, infra-red radiation is used to accomplish rapid drying. The tester has a sensitive torsion balance which permits rapid determination directly from the balance scale, eliminating the need for computing or calculation to obtain results. This method is useful for the in-process determination of moisture because the results may be obtained in minutes.