From The July 1999 Issue of Nutrition Science News
By Nancy Scanlan, D.V.M.
Natural solutions for seasonal allergies in dogs and cats
Dogs, and an increasing number of cats, often have seasonal allergies that send their owners scurrying for answers each summer. Although some pets may have weepy eyes and runny noses, the primary sign of allergies is constant scratching.
Often, the cause of all this itchy skin is inhaled allergens. In addition, food or contact allergies, infections, skin damage, or conditions such as seborrhea, a disease of the sebaceous glands, can also be involved. The degree of pruritus, or excessive itchiness, is determined by the amount of allergens in the pet's environment, the number of things the pet is allergic to and how many other skin problems the pet has. [1, 2] Veterinarians can perform skin cultures and blood tests to more accurately determine the cause of the itching.
In my practice, I find pruritic pets are usually allergic to one or more of the following: flea saliva or a reaction to a flea bite; pollen from local grasses, trees and bushes; molds and fungal spores; dust mites; fibers, especially wool; and foods, particularly those with artificial flavors, colors and preservatives.
Allergies are caused by the interaction of allergens with antibodies, the chemical messengers in the immune system. In many allergic reactions, a particular class of antibodies, called IgE, attacks the allergen. The IgE-allergen complex then affects mast cells in the body causing them to release histamine-containing granules. Histamine causes the cascade of inflammatory events associated with an allergy attack.
Allergies can develop in young or old animals, though they usually aren't born with them. Over time, animals can become sensitized to allergens, and sooner or later their allergic threshold will be reached. In a highly allergy-prone animal, it may only take a few exposures to sensitize them. In others it may take years.
In an environment with a high concentration of allergens, even non-sensitive animals can become sensitized. Once the allergic threshold is reached, a small quantity of the allergen can have a major effect, often causing full-body itching. Allergy thresholds can also vary. A pet stressed from allergies, anxiety, climate, diet, disease, skin infections and vaccines will have a lower threshold than a less-stressed pet. A pet's threshold can be raised by improving its nutrition and health, controlling parasites and easing stress.
I suggest owners take a three-pronged approach to relieving their pet's seasonal allergies: remove or minimize allergens, relieve itching and support the animal's overall health.
One of the first steps owners can take is to decrease allergens in their homes. High efficiency particulate air (HEPA) filters can minimize airborne allergens. With contact allergies it is a matter of identifying and removing the suspected allergen from the animal's environment. Results are seen fairly quickly with these methods if the problem is an uncomplicated genetic sensitivity or a contact allergy. 
An important part of allergen elimination is flea control.  Many animals have low thresholds for fleassometimes one flea bite can cause severe itching. Flea control must encompass the animal, the house and the yard. Advise customers to be careful with natural flea control in cats because flea-repelling aromatic herbs such as pennyroyal (Hedeoma pulegioides) and citrus-based products such as d-limonene, while effective flea-killers when used externally on pets, can also be toxic to cats if not used properly. A pennyroyal shampoo or dip should only be used on cats as long as it is rinsed off thoroughly, and citrus-based products should be diluted. Pyrethrin-based insecticides (derived from chrysanthemum flowers) are fine. For bestand safestresults customers should follow product directions or consult with their veterinarians.
Feeding a pet nutritional yeast, B-complex and garlic can make it less tasty to fleas. Once enough garlic, for example, is in the pet's bloodstream it permeates breath and sebaceous glands, deterring fleas. Owners can add grated garlic to a pet's food or "pill" the pet with whole or sectioned, peeled cloves.
Diatomaceous earth (DE) controls fleas in carpets by dehydrating them. DE does not have the potential toxicity of borate-based products as long as it is applied properly. [4,5] DE should be worked deep into the carpet with a broom then the surface powder vacuumed to prevent pets from inhaling any remaining particulate.
Food allergies for pets are more difficult to isolate than external allergies, and should be explored as a last resort unless there is an obvious and immediate reactionpositive or negativeto a change in food. The reason is, an animal with food allergies may continue to itch for up to three months after the offending food is removed.  Pet owners trying to isolate a food allergy should feed their pets a hypo-allergenic diet without artificial flavors, colors, preservatives, by-products or meat meal. It should contain real meat, grains and vegetables, as well as a vitamin and mineral supplement.  The meat and grain should be varieties the pet hasn't yet been exposed to. The pet should be fed this diet exclusively for three months to evaluate the diet's effectiveness.
Allopathic drugs usually work quickly to stop itching, but they tend to have a decreasing effect each year. A variety of natural approaches to itch control may be more effective. After removing the irritants or allergens, the goal is to decrease histamine production and inflammation as well as allergen sensitivity while increasing natural antihistamines and anti-inflammatory substances in the body.  (Doses for all supplements vary based on pet size. Please see sidebar for guidelines.) Following are some of the best internal and topical remedies.
Aloe vera gel, applied topically, moisturizes dry skin and can heal sores caused by excessive scratching. Chilled aloe gel is particularly effective at soothing itchy skin, though it is less effective at healing primary skin infections. 
Essential fatty acids (EFAs) lubricate dry skin and control inflammation.  Adding flaxseed, fish, safflower, borage or evening primrose oil to a pet's food is an easy way to increase EFA consumption. Monounsaturated oils such as avocado and olive oil can also help reduce inflammation.
Herbal combinations can help heal the skin and relieve itching. There are at least two Chinese patent formulas that can help because of their bacteriostatic and antifungal effects.  The first formula is Chuan Yin Lian Kang Yang Pian, which contains isatis extract (Istis tinctoria) called Da Quing Ye, oldenlandia (Oldenlandia diffusa) called Bai Hua She She Cao and lonicera (Lonicera japonica) called JinYin Hua, as well as other synergistic herbs. The second is Phellodendron, which includes phellodendron (Phellodendron amurense) called Huang Bai, codonopsis (Codonopsis pilosula) called Dang Shen and atractylodes (Atractylodes macrocephala) called Bai Zhu, along with other complementary herbs. These formulas are also said to promote healing and itch relief with antipruritic and anti-inflammatory actions. Most herbs are rather bitter and will need to be given in pill form or well-disguised in food. Some pets are sensitive to certain herbs and may develop nausea, vomiting or diarrhea, so it is best for customers to work with a holistic veterinarian.
The following nutritional supplements can help decrease the inflammatory response, help the immune system fight off infection and heal a number of skin problems. 
Vitamin A helps heal skin by decreasing inflammation. It also decreases dryness and dandruff. Vitamin A deficiency can cause delayed healing and research shows that a localized deficiency at the skin level, which may not be discernable in serum tests, could be responsible for hyperkeratosis, a thickening of the keratin layer of the skin and sebaceous glands.  Doses should not exceed 200 IU per pound of body weight per day. [3 ]Overdose can cause calcification of joints as well as seborrhea. 
B vitamins help the body deal with stress and for that reason alone are helpful. Many B-vitamin deficiencies are associated with depression, dermatitis, diarrhea, fatigue and nervousness.  This is not to say that every skin infection or irritation is caused by a B-vitamin deficiency; however, in an animal with a poor diet or nutrient absorption problems, adding B complex can make a difference.  B complex is available in many of the pet supplements available on the market or owners can use a B50 supplement designed for humans.
Bioflavonoids such as quercitin and rutin are scavengers that bind heavy metals used in the formation of free radicals. Free radicals are a byproduct of inflammation and, in turn, cause more inflammation. Bioflavonoids help break the cycle by reducing free radical formation and thereby reducing further inflammation.  Bioflavonoids are most easily added with a supplement containing vitamin C and rose hips.
Vitamin C deactivates and detoxifies histamine.  In addition it increases production of anti-inflammatory prostaglandins.  Vitamin C is also needed for production of steroidal adrenocortical hormones, which help the body control inflammation. Vitamin C protects against deficiencies of vitamins A, B12, E, folic acid, thiamin, riboflavin, pantothenic acid and biotin, which are all important for healthy skin.  While dogs and cats produce their own vitamin C, levels may decrease in animals that are stressed. 
Vitamin E has anti-inflammatory action.  Estrogen decreases available vitamin E so non-neutered female dogs and cats have a greater need for supplementation.
Essential fatty acids play a part in controlling the prostaglandins involved in inflammation. Omega-3 fatty acids increase production of the anti-inflammatory prostaglandins. [14,15] Omega-3 and omega-6 fatty acid deficiencies can cause eczema, another irritating skin condition. Flaxseed oil and fish oil are good sources of omega-3 fatty acids.
Gamma linoleic acid (GLA), an omega-6 fatty acid, is converted in the body to prostaglandin E1, the anti-inflammatory prostaglandin. Rich sources of GLA are evening primrose, borage and black currant oils. GLA supplementation can soothe rough, dry skin. [14,16]
Minerals such as zinc, copper, iodine and calcium are necessary for healthy skin.  Zinc is a cofactor and modulator of many biological functions. Relative or absolute zinc deficiency is documented or suspected in at least three dermatologic conditions that cause itchy skin.  Advise owners to add mineral supplements under veterinary supervision because the mineral balance can easily become disrupted with supplementation.
It can often take up to a month for pet owners to see the results of their holistic allergy relief efforts, but this approach can decrease their pet's reactions to allergens in the long run. Remind pet owners who are new to natural methods to be patient. The best advice to offer customers seeking natural remedies to manage their pet's seasonal allergies is to work with a holistic veterinarian.
Nancy Scanlan, D.V.M., is a certified veterinary acupuncturist practicing in Sherman Oaks, Calif.
Determining Pet Supplementation Doses
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