Hair, Footpads, Nails/Claws, Hoofs/Horns

Common Integument Overview

  • Refers to the ordinary skin and its various coverings including hair, skin glands, claws, hoofs, and horns.

Learning Objectives

  • Define the common integument.

  • Describe the role of skin in the integumentary system.

  • Describe different types of hair: development and characteristics.

  • Describe footpads and their development in various species.

  • Define nails, claws, and hoofs, emphasizing differences across species.

  • Define horns and discuss the relevance of cornual processes and frontal sinuses.

Function of the Skin

  • Protection: The skin acts as a barrier to protect against physical injury and external pathogens.

  • Temperature Control: It helps maintain body temperature through regulation of sweat and blood flow.

  • Sensory Response: Enables the organism to react to external stimuli such as touch, pain, and temperature changes.

Skin Structure

  • Layers of Skin:

    • Epidermis: The outermost layer, primarily comprised of keratinized cells for protection.

    • Dermis: The inner layer containing blood vessels, nerves, and connective tissue.

    • Subcutis/Hypodermis: Loose connective tissue that provides insulation and cushioning.

  • Components: Sebaceous glands, sweat glands, hair follicles, and arterial networks can be found within these layers.

Hair Types

  • Three primary types of hair:

    1. Guard Hairs: Stiff and straight providing a protective topcoat.

    2. Wool Hairs: Fine, wavy hairs that create a soft undercoat, typically shorter and more numerous.

    3. Tactile Hairs: Thicker hairs often associated with sensory functions (e.g., whiskers).

Development of Hair

  • Hair follicles develop from ectodermal buds; complex structures create the variety of hair types.

  • Guard hairs grow from specific follicles, with variations seen across species.

Guard Hairs

  • Influence the coat's appearance and functionality (e.g., water runoff).

  • Variations exist based on specific animal characteristics, such as the coarse hair of a horse's mane or the bristles of a pig.

Wool Hairs

  • Located beneath guard hairs, contribute to insulation and softness in the undercoat.

  • In some species, multiple hair types share a follicle structure (primary and secondary hairs).

Tactile Hairs

  • These hair types provide sensory feedback and are typically found on the face and lips.

  • Have a unique structure with a blood-filled sinus that supports their sensory function.

Footpads

  • Composed of thick epidermis and subcutaneous cushioning, footpads help absorb impacts and reduce friction when animals walk.

  • Variations exist among species: e.g., ruminants have digital pads involved in hoof structure, while horses have a distinct "frog".

Nails, Claws, and Hoofs

  • Serve purposes such as scratching and digging, playing various roles across species.

  • Structure of Hoofs:

    • Comprised of the wall, sole, and associated pad, with specific adaptations for each animal type.

Clinical Considerations with Horns

  • Horns in ruminants grow continuously and have a base formed by the cornual processes associated with the frontal bones.

  • The importance of understanding the anatomy is highlighted when considering procedures like dehorning, due to the involvement of sinus structures.

Practice Questions

  1. Identify the structure associated with the cornual process in cattle.

  2. Name the structure numbered in the attached image (4).

  3. Correctly identify characteristics of wavy wool hairs and their functional purpose.