Pet owners fact sheet on Skin, Hair and common skin disease in Cats and Dogs.
by Unknown - 21:43 on 07 March 2012
Pet owners Factsheet
Skin, hair and common skin diseases in pets
Like humans pets also suffer from diseases, skin problems and general health issues. This factsheet contains useful information on the functions of pet skin and hair and also the most common problems found amongst pets along with signs to look out for and treatments.
Problems with animal skin is one of the most common reasons for a trip to the vets amounting to at least 20% of vets clientele being a result of a skin problem.
Skin
Skin is the largest organ on a pets body and has lots of different important functions essential to life. It is one thing that provides the body with a barrier from the environment.
Skin functions also help to prevent infection, viruses and fungus from attacking the body thus also preventing important materials such as water from escaping. It helps in the regulation of body temperature and also helps to regulate blood pressure. It is stretchy and flexible to allow movement, contains pigmentation which protects the skin against the sun and also acts as a reservoir for water, nutrients and is also the site of vitamin D synthesis.
As pets are generally covered in hair their skin is far thinner than that of humans and much more fragile but where the skin is exposed the animal produces much thicker skin for example the footpads and also the nose. The skin is generally thinner on the inner surface of the legs, on the belly, in the armpits and over the ears.
The skin has 2 main components, the outer component called the Epidermis and the inner component called the Dermis.
The Epidermis which is divided into a number of layers and is a major barrier from restricting loss of water and other materials from the body. It also prevents entry of infectious microorganisms like bacteria to the body.
The Dermis which is a much thicker layer and contains blood vessels, nerves, skin glands, hair follicles, collagen and elastic fibres. The collagen and elastic fibres gives the skin strength and allows it to be flexible. The main function of the Dermis is to support and nourish the Dermis and the hair follicles. The Dermis also has bundles of muscle fibres, these attach to the end of the hair follicles and when they contract the hair stands up. This helps to insulate animals in cold weather and also make the animal appear bigger when in fear of being attacked.
The skin also contains various glands, namely Sweat Glands, Sebaceous Glands and Anal Glands.
Sweat Glands:- Contrary to popular belief that dogs cannot sweat they do have a large number of sweat glands in the skin. They don't open directly onto the skin surface in the same way as humans instead they discharge through openings in the hair follicles. Sweat in the dog has little to do with temperature regulation but does provide an important role in skin disinfection.
Sebaceous Glands:- These produce sebum which is extremely important in the waterproofing of the skins surface. It maintains the skins flexibility and helps the body resist infection.
Anal Glands:- They secrete an extremely disgusting smell and are thought to be a pheromone for marking territory.
Animals also have special scent glands which produce pheromones and aid communication with other animals.
Hair Follicles
Hair follicles contain bundles of about a dozen hairs. Each bundle comprises of a large, long primary hair or guard hair and also several secondary hairs called an undercoat. The undercoat is thinner and much more wool like. In some breeds of animals such as poodles there are very few guard hairs and lots of undercoat hairs. this gives them their woolly coats. Other breeds such as Rottweiler's have lots of guard hairs so their coat feels harsh and glossy.
Hair is produced by the hair follicles and its growth is controlled by a number of things such as:
· Seasons
· Nutrition
· Hormones
· Environment
In both dogs and cats the rhythm of shedding occurs independently in each follicle. Pets coats are normally thicker in the winter months and thinner during the warmer weather. Pets living in homes may shed all year round due to central heating which can confuses their bodies into thinking it is summer months. Hair growth normally slows during the summer months and increases during winter months. During summer hair grows approximately 1mm per week and the growth pattern can be affected by certain contributory factors. Once hair has stopped growing the hair dies in the follicle after which it then sheds and another takes its place. Hair moults in Spring and also in autumn months and generally lasts about 6 weeks. A new coat is normally in place after approximately 4 months. Some breeds shed twice a year and other breeds like Dalmatians shed moderately throughout the year. Some for example, Poodles don't shed at all.
Hair is there for a variety of reasons:
· Insulating the animal against the cold weather.
· Acts as a protection against skin injury.
· Offers colour and also camouflage.
· Acts as a sensory.
Whiskers and Eyelashes
These are made of sensory hairs also called Tactile hairs and are also found in the ears. These hairs are normally twice as thick as guard hairs. They have a much deeper follicle and have a greater nerve and blood supply. The hairs act as a sensory fingers to judge distances around their heads and to obtain information in the environment indicating to the animal the position of the head and therefore the body in relation to the given space. It allows for safe passage for the animal.
Diseases:
Diseases of the skin are very common, challenging and yet frustrating for the animal, owners and also the vets. Many different skin problems are very similar in symptoms and can take a long time to find the cause and a true diagnosis.
Allergic skin diseases are the most common but are also difficult and frustrating conditions to diagnose and treat. An allergic reaction or allergy which occurs when the immune system makes an exaggerated response to a substance. There are four major foreign materials which causes this hyper sensitivity and they are:
· Flea saliva
· Food ingredients such as Gluten, beef and dairy products
· Inhaled particles such as dust and pollen
· Contact allergies such as shampoo
Animals are not born with allergies but develop them and may develop them at any time after repeated exposure to an allergen. Like humans they can also develop more than one allergy.
General major causes of allergies:
· Flea Allergic dermatitis - This is the most common allergy in cats and dogs.
· Inhalation Allergies - The 2nd most common allergy. This can be caused when an individual inhales particles such as dust, pollen or mould and has a reaction to it. It is equivalent to the human form of hay fever and asthma but instead of getting wheezy they develop skin irritation whereby it makes their skin very red and, itchy and in some cases sore. It is normally diagnosed by doing an intradermal allergy skin test which involve injecting very small volumes of a range of liquids allergens into the skin and noting the reactions to each one. Treatments are normally by way of steroids, antihistamines or essential fatty acids supplements which reduces irritation and inflammation.
· Dietary Allergy - Like humans pets can be allergic to a wide range of foods although dairy, gluten and beef seem to be the most frequent. Diagnosis is normally based on a dietary exclusion trial which does not include the proposed allergen and diagnosing via process of elimination.
· Contact Allergy Dermatitis - This is generally uncommon as the animals hairs prevent substances from touching the skin but when it is seen it usually has the symptoms of itchy feet, chin, elbows and hocks. Substances which can cause the allergies include plants, disinfectants, shampoos, ointments, insecticides and fabrics. Treatment includes exclusion of the suspected offending allergen for two weeks then re introducing it back to the pet again to see of a reaction occurs and a general theme of process of elimination.
· Hives - Also known as Uticaria. It produces multiple weal's and swellings suddenly on the skin. The causes are usually food, drugs, vaccines or insect bites. Treatment is normally with antihistamines or an anti inflammatory and if the culprit allergen is identified then it should be removed from the animals environment altogether.
· Drug allergy - Sometimes animals may develop an allergic reaction to a drug given orally, by injection or topically on the skin surface. Many drugs have the potential for causing this condition and symptoms are variable but if an allergy occurs the drug should not be given to the animal again.
1. Bacterial skin diseases:
This is called a pyoderma and is quite common in cats and dogs. It usually occurs as a result of another skin disease like an allergy altering the skins surface and allowing bacteria to multiply and aggravate the original condition.
Most common pyoderma's seen are:
· Acute moist dermatitis - Otherwise known as wet eczema, hotspots or summer eczema. Causes are mainly Self Trauma, flea allergy, blocked anal glands, ear infections and other irritant diseases and generally Occurs in hot weather, and common in longer haired breeds. Signs to look out for are red areas, moist, painful, loss of hairs around the affected areas.
Treatment: clipping the surrounding hair around the affected area to allow the skin to be ventilated, cleaning and application of a prescribed cream.
· Skin fold Pyoderma - Skin folds are when two surfaces of skin are in close contact with one another preventing ventilation and creating a warm environment in which bacteria will multiply.
Treatment: Antibacterial shampoo and/or surgical removal of the excess skin.
· Superficial Pyoderma - Bacterial infections within the skin and they usually cause small pustules or whiteheads. Generally happens amongst the younger pets which is equivalent in acne in human teenagers.
Treatment: Antibiotics and antibacterial shampoo for 3 weeks.
· Deep Pyoderma - A skin infection deep inside the skin. It is usually caused by and underlying hormonal or immune disease. these are very serious and potentially life threatening and require the most aggressive antibiotic treatment. An example of a deep pyoderma is an infected pressure sore in very ill animals.
Treatment: Very aggressive antibiotics.
2. Hormonal skin diseases:
Hormones, particularly thyroid hormones, sex hormones and steroids can seriously influence skin function. The reason why hormones cause skin disease is very complex and poorly understood. It usually causes symmetrical hair loss, pigmentation and thickening/thinning of the skin.
Causes are:
· Hyperthyroidism - A lack of thyroid hormones
· Cushing's syndrome - An excess production of steroids from the adrenal glands
· Sex Hormone related - Excess production of female related hormones.
3. Fungal:
· Ringworm - This is actually a fungal infection and not a worm as suggested in the title. There are a number of fungus which can cause ringworm, /the commonly occurring ones being Microsporum and Trichohyton species. Areas affected are usually small, round lesions with hair loss and a greying scaling and crusting. the lesions are usually very itchy. It can be passed on by direct contact with another infected animal or by contact with an animals collar etc. It is infectious to humans so caution should be taken when handling an animal infected with ringworm. Ringworm normally gets better by itself after 6-8 weeks but treatment with antifungal antibiotics is usually advised due to the possible infection risks to people.
· Yeast Infections: - Yeasts are single celled organisms which are found on surfaces of all living things including animals. when the immune system is healthy the body is able to destroy the yeast. However, when the immune system is weak the yeast will grow out of control. Yeast infections in animals are usually found in the skin and ears and are caused by an organism called Malesezzia. It causes skin lesions or sores and are usually red in appearance and accompanied by areas of increased pigmentation, hair loss and scaly skin or greasiness. The dogs are usually very itchy and have a musty type of odour. The most common sites for these sores are the underside of the neck, the belly and the feet especially between the toes. Treatment usually consists of a special shampoo.
4. Nutritional:
· Nutritional skin diseases - are usually caused by deficiencies or imbalances in an animal's diet. For example if an animal is being fed a home cooked diet or a poor quality commercial food are more likely to suffer than the ones being fed a commercial diet from a reputable company. symptoms are variable and wide ranging and can include Scurvy, dry, poor quality coat, hair loss, crusting and scaling. Treatment usually consists of changing and supplementing the diet to eliminate the imbalances.
5. Tumours:
· Tumours - are often seen in animals skin. They occur when cells multiply out of control and generally classified into categories:
· Benign - which are slow growing and non cancerous tumours and generally has no tendency to spread.
· Malignant - Cancerous tumours which have a tendency to grow and spread rapidly.
Early treatments are always advised and are genrally diagnosed by way of a biopsy and treated with surgical removal if needed.
6. Sunburn:
Pets can get sunburnt too just like we can and is generally more common amongst fair haired pets and white coated animals and also hairless pets. They also get skin cancer from too much sun exposure. The areas on a pet most likely to get sunburnt are:
· Nose
· Tips of the ears
· Around the mouth
· Underbelly
· Eyelids
Sunscreen can be out on the areas which are high risk to reduce the chances of sunburn and cancers.
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