Integumentary System EQS 110

Transcription

1 Integumentary System EQS 110

2 Table of Contents Click on the different sections of the table of contents to jump through this document Functions of the Integument... 3 Anatomy of the Skin... 3 Epidermis... 3 Dermis... 4 Sweat Glands... 4 Sebaceous Glands... 4 Hypodermis... 4 Management of the Skin Dermatitis... 5 Dew Poisoning/Scratches... 5 Causes of Dew Poisoning... 5 Treating & Preventing Dew Poisoning... 6 Rain Rot... 7 Causes of Rain Rot... 7 Treating Rain Rot... 7 Thermoregulation... 8 Cooling Off... 8 Convection... 8 Evaporation... 9 Radiation... 9 Conduction... 9 Warming Up Self-Knowledge Checks Answers Glossary... 13

3 Functions of the Integument Integument refers to the skin, which is the largest (and heaviest) organ of the horse s body. It is a complex, highly organized system of nerves, tissues, and cells designed to take data from the environment and relay it to the brain, making it the principal organ of touch. In addition to connecting the horse s internal environment with its external surroundings, other main functions of the integumentary system include: Environmental Protection The skin is the horse s 1 st line of defense between the environment Temperature Regulation The skin enables the horse to keep itself cool and warm Synthesis of Vitamin D Excretion of Waste When exposed to enough sunlight, the skin has the ability to create Vitamin D Waste products, such as sweat, can be excreted through the skin via the pores Anatomy of the Skin A horse s skin is comprised of three layers: Epidermis Dermis Hypodermis We will look at each of these layers in further detail to understand their importance and role within the integumentary system. Epidermis The epidermis is the outermost layer of skin (it is the layer that we can see). Made up of layers of epithelial (skin) cells, the bottom of the epidermis contains keratinocytes, cells that create keratin. Keratin is the main fibrous component of hair and hooves. Epithelial cells migrate towards the surface over a 3 4 week period and replace older cells that are shed. In addition to skin cells, the epidermis also contains pores which allow for the excretion of waste.

4 Dermis The dermis is the deeper and thicker layer of skin. It is comprised of a densely, woven network of collagen, elastic, and connective tissue fibers which give the epidermis support and strength. It is rich in blood vessels, nerve endings, lymphatic vessels, hair follicles, and sweat and sebaceous glands, the two main glands in the dermis. Sweat Glands Sweat glands are responsible for releasing secretions onto the surface of the skin through millions of pores. The horse is one of the few animals that sweat readily; sweat glands appear all over the body except the legs and are most numerous behind the ears, chest, and flank. Sebaceous Glands Sebaceous glands are attached to hair follicles and produce sebum, an oil that waterproofs and coats the hairs to prevent them from becoming dry and brittle. Frequent grooming can increase sebum production, giving your horse that illustrious shine. Hypodermis The hypodermis is the bottommost layer of the skin. Subcutaneous fat, which provides insulation, an energy source, and a cushion between the dermis and muscle, is stored here.

5 Management of the Skin Dermatitis The health of your horse s skin can provide numerous insights into your horse s health. Ideally, a horse should have a soft, supple, and glossy coat. Tight skin is often an indicator of dehydration while a dull, flaky coat may indicate poor diet, the presence of parasites, or even emotional distress and anxiety. Poor coat health can also be related to improper grooming, either through a lack of grooming or inappropriate grooming techniques. For example, bathing a horse too much, especially with harsh chemical agents (dish soap is one product unfortunately used rampantly throughout the racetrack), can strip the coat of its natural oils. Issues of the skin are often lumped together under an umbrella term known as dermatitis, which means an inflammation of the skin. There are many problems that can affect a horse s skin from insect allergies to fungal, viral, or bacterial infections. Two common issues we encounter are dew poisoning/scratches and rain rot. Dew Poisoning/Scratches Dew poisoning, also called, scratches, greasy heel, or mud fever, is a type of dermatitis that affects the distal limb, particularly the fetlock, pastern, and heel. This issue is characterized by the formation of thick, tightly adherent crusts/scabs which may show heat, sensitivity to palpation, and even bleeding when the horse moves. Causes of Dew Poisoning The cause of dew poisoning is often associated with wet environments, such as moist dewy grass and mud. Constant moisture can become an irritant as it penetrates the delicate skin and makes it vulnerable to infection. Various organisms, such as bacteria or fungi, can get into microscopic breaks in the skin and then fester. Dew poisoning can also be caused by mechanical irritation due to riding over sand, stone dust, or dry and dusty terrain. These surfaces can trap small particles in the folds of the skin along the back of the pastern as the horse moves, which then irritates the area and makes it susceptible to infection.

6 Treating & Preventing Dew Poisoning Treating dew poisoning involves reversing the steps that caused it in the first place. A horse with dew poisoning should be maintained in a dry area, preferably on shavings or fine sawdust as straw has a greater risk of bacterial and fungal contamination. If a horse has very long hairs on the distal limbs they should be carefully clipped in order to reduce the amount of moisture staying on the skin. Once the horse is being managed appropriately, the crusts/scabs can be dealt with topically. Washing the affected area with an antimicrobial shampoo daily can help treat the issue, but care must be taken that the limb is not being overwashed, aggressively picked at, or not being dried thoroughly after washing. Tea-tree based washes are often suggested as they are fairly gentle, yet effective. There are a variety of ointments on the market claiming to treat dew poisoning/scratches but which product to choose heavily depends on the severity of scabbing; consult with your veterinarian as he/she may be able to prescribe you a specific ointment that is created by their practice. Preventing dew poisoning will revolve around management conditions that ensure the horse is not constantly standing in wet, moist conditions. For example, you may need to alter the time of day turnout occurs in order to minimize contact with wet grass. For racehorses, dew poisoning often occurs in response to mechanical irritation from the racetrack or from not drying the legs thoroughly after washing. If your horse is being washed following exercise, be sure to dry the legs with clean towels to ensure no moisture is left behind.

7 Rain Rot Rain Rot, also called Rain Scald, is a dermatological condition caused by a bacterial organism known as dermatophilus congolensis. This organism lives in the soil and can inhabit the skin without adverse effect until there is either trauma or repeated exposure to moisture, such as rain. Rain rot is known for presenting painful scabs that form over the horse s topline. When these scabs are pulled away, they tend to take clumps of hair with them, leaving bald patches. Areas of rain rot can become very sensitive, which can impair the use of the horse until the condition is resolved. Causes of Rain Rot While dermatophilus congolensis is at the root of this issue, rain rot is more apt to appear on horses that are immunocompromised, such as young and older horses. Rain rot is also believed to be contagious and can be spread via grooming tools, blankets, tack/equipment, etc. As a condition that thrives on moisture, this ailment is commonly seen in months where precipitation is high. Treating Rain Rot Similar to dew poisoning, a condition that thrives on moisture is often resolved by ensuring a dry environment. Horses with rain rot should be kept dry and bathed daily with an antimicrobial shampoo. The bacteria live under the scabs, so gentle removal during a bath when they are already softened will expedite healing. If you have a very severe case of rain rot, administration of antibiotics may be required. For horses that live outdoors, a rain sheet may be needed to prevent future cases.

8 Thermoregulation Thermoregulation refers to the ability to regulate core body temperature. As discussed in the beginning of the lecture, a primary function of the skin is to regulate temperature in order to keep the horse cool or warm. Due to the anatomy and structure of the skin and coat, horses are actually good insulators of heat it is far easier for horses to warm up in cold weather than to cool down in hot weather or after intense exercise, a point that is very important when dealing with the athletic horse. Internally, horses are also continuously generating heat as a by-product of metabolism, which is the utilization of energy. When a horse exercises, only about 25% of the energy is used for muscle movement while the remaining 75% is converted to heat. You can probably begin to imagine then how important it is that we as equine caretakers are ensuring the horse s ability to properly regulate temperature! Cooling Off If a horse s core body temperature (which is F) rises above normal due to environmental conditions or exercise, the horse has a variety of mechanisms to cool itself convection, evaporation, radiation, and conduction. Convection Convection refers to the movement of heat from deep within the horse outward into the air. As air moves over the horse s skin, heat and moisture are picked up and carried away as new air molecules come into contact with the skin. Hot sticky, humid days with little to no wind though will impede convection, making it harder for your horse to cool off. One way that we can improve convection as a thermoregulatory process is through the use of fans placing a fan in front of a hot horse or in a stall can help carry the hot air your horse is producing away faster so they can to cool off more quickly.

9 Evaporation As the core body temperature rises, capillaries under the skin widen (known as vasodilation), which increases blood flow to the skin and heat from the blood is then transferred to sweat. As the sweat evaporates, this cools the horse down. Unfortunately, hot, humid weather conditions can inhibit evaporation, resulting in sweat remaining on the body, insulating the horse, and causing him to heat back up. In this situation, you would want to use other thermoregulation techniques, such as a fan (convection), shade (radiation), or rinsing with cold water (conduction) to help keep the horse cool. Do not blanket a horse during hot and humid conditions as it will block evaporation from occurring. Radiation Radiation as a thermoregulation technique involves the air around the horse being cooler than the horse s body temperature. The heat from the horse s body then radiates to the air. Radiation will not be effective is the sun is beating down on the horse, so finding shade will be key in making this process more efficient. Conduction Conduction refers to the transfer of heat from the body to cooler water or the ground if the horse is laying down. One example of conduction is bathing or rinsing your horse with cold water. This practice is often done on hot days after exercise to help the horse cool down. While this can be an effective strategy, a key part of this process is to remove excess water from the body with a sweat scraper; this will help physically reduce heat and allow for better evaporation. If you do not scrape a horse following a bath or rinse, the water will sit on the body and insulate it, resulting in the horse heating back up.

10 Warming Up If a horse s core body temperature is lower than normal due to environmental conditions, the horse can warm itself through a variety of mechanisms: Vasoconstriction Shivering Raising of Hair Increasing Feed Intake Sun-Bathing Capillaries under the skin will contract (get narrow) to reduce heat loss Rapid contraction of the muscles under the skin to produce heat Hair will be raised upright when extra insulation is needed Increasing fiber intake (for example providing more hay) can increase the amount of body heat produced Standing under the direct sun A horse might employ one or many of these thermoregulation techniques in order to stay warm in colder climates but there is one item that has been left out of the discussion blanketing. Blanketing is a topic that many equine caretakers get very passionate about; opinions range from the horse should never be blanketed to designing a blanketing schedule based on various ranges of temperatures. Horses do have an incredible ability to take care of themselves in all types of climates and when a horse is in good health, provided ample amounts of forage (typically hay if we are looking at winter climates), and given access to shelter blanketing is not always required. That being said, if your horse has been body clipped, carries a thinner coat than normal, has been under heat lamps, is going from a warm climate to a cold climate, is going to be encountering direct contact with wet weather in extremely cold temperatures, then blanketing may be needed. Typically, racehorses are blanketed because we body clip or want to keep the coat thinner in order to make it easier to cool out after exercise. Knowing when and when not to blanket is going to depend on your horse(s) and situation. To help guide your decision further, review some of the following articles that discuss the finer points of when and when not to blanket: To Blanket Your Horse? Or Not? EquiSearch To Blanket or not to Blanket? That s a Good Cold-Weather Question Colorado State University Your blanketing questions answered - Equus

11 Self-Knowledge Checks 1. The is the outermost layer of skin. a. Dermis b. Epidermis c. Hypodermis d. Outer dermal layer 2. Which gland in the skin assists with the horse s ability to thermoregulate? a. Sweat Glands b. Sebaceous Glands 3. A horse that has thick crust/scabs on the distal limb is suffering from: a. Rain Rot b. Dew Poisoning c. Stocking Up d. Lymphangitis 8. Horses that are hosed off with cold water following exercise should not be scraped (have excess water removed) a. True b. False 9. What are ways in which a horse can warm itself during cool temperatures? 10. What is one condition that might require a horse to be blanketed? 4. Rain Rot is a contagious dermatological condition a. True b. False 5. What do Dew Poisoning and Rain Rot have in common? a. They can easily be treated with NSAIDs b. They are a result of a virus c. They thrive in wet, moist conditions d. All the above 6. Thermoregulation is concerned with: a. The ability to cool or warm oneself b. The ability to create Vitamin D c. The ability to fight off pathogens d. The ability to produce coat oils 7. Placing a fan on a horse s stall is utilizing this thermoregulation technique a. Conduction b. Radiation c. Evaporation d. Convection

12 Answers 1. The is the outermost layer of skin. b. Epidermis The epidermis is the outermost layer of skin (the layer that we can see). It is made up of epithelial (skin cells) and contains pores 2. Which gland in the skin assists with the horse s ability to thermoregulate? a. Sweat Glands Sweat glands allow for the secretion of sweat, which helps cool the horse through evaporation 3. A horse that has thick crust/scabs on the distal limb is suffering from: b. Dew Poisoning Dew Poisoning is a skin condition in which thick, tightly adhered crusts/scabs form on the distal limb 4. Rain Rot is a contagious dermatological condition a. True Rain Rot has been found to be contagious and can be easily spread via grooming tools, blankets, tack/equipment, etc. 5. What do Dew Poisoning and Rain Rot have in common? c. They thrive in wet, moist conditions 7. Placing a fan on a horse s stall is utilizing this thermoregulation technique d. Convection Convection refers to the movement of heat from deep within the horse outward into the air. As the air moves over the horse s skin, heat and moisture are picked up and carried away increasing the movement of air, as with a fan, can aid this thermoregulation technique 8. Horses that are hosed off with cold water following exercise should not be scraped (have excess water removed) b. False Hosing a horse off with cold water is an example of conduction the transfer of heat from the body to cooler water or the ground. A key part of this is scraping the horse (removing excess water) to allow for evaporation leaving water on a hot horse will insulate him and cause him to heat back up 9. What are ways in which a horse can warm itself during cool temperatures? Vasoconstriction / Shivering / Raising the hair / Increasing feed intake / Sun-bathing 10. What is one condition that might require a horse to be blanketed? The horse is body clipped, carries a thinner coat, has been under heat lamps, is going from a warm to cold climate, direct contact with wet weather in extremely cold conditions Dew Poisoning and Rain Rot are both dermatological conditions that thrive in wet, moist conditions. One the key ways to treat these ailments is by ensuring the affected areas are kept dry 6. Thermoregulation is concerned with: a. The ability to cool or warm oneself Thermoregulation refers to the ability to regulate core body temperature in order to cool down or warm up

13 Glossary Conduction Refers to the transfer of heat from the body to cooler water or the ground if the horse is laying down Convection A form of thermoregulation, refers to the movement of heat from deep within the horse outward into the air Dermatitis An inflammation of the skin Dermis Deeper and thicker layer of skin Dew Poisoning Also referred to as pastern dermatitis, scratches, mud fever, and greasy heel, a form of dermatitis that affects the distal limb, particularly the fetlock, pastern, and heel Epidermis Outermost layer of skin, made up of epithelial cells Epithelial Cells Skin cells Evaporation A form of thermoregulation, evaporation of sweat from the skin has a cooling effect Hypodermis Bottommost layer of skin, stores subcutaneous fat (adipose tissue) Integument Refers to the skin Keratin The main fibrous component of hair and hooves Metabolism The utilization of energy Radiation A form of thermoregulation, involves the air around the horse being cooler than the horse s body Rain Rot Also called rain scald, a type of dermatitis caused by a bacterial organism Sebaceous Glands Found in the dermis, produce sebum Sebum An oil produced by the sebaceous glands that waterproofs and coats the hairs to prevent from becoming dry and brittle Sweat Glands Found in the dermis, responsible for releasing secretions on the skin through pores Sweat Scraper A tool used to remove excess water from the horse s body after a bath or rinse Thermoregulation Refers to the ability to regulate core body temperature Vasoconstriction Narrowing of the blood vessels Vasodilation Widening of the blood vessels