Canine Atopy
Canine atopy is a hypersensitivity reaction which occurs when genetically predisposed dogs inhale various allergens, for example, moulds, pollens or dust mites. A strong breed predilection has been identified. It can occur in any breed but we see many affected West Highland White Terriers, Staffordshire Bull Terriers, Labradors, Pugs and Cocker Spaniels.
Atopy is the second most common skin disorder in dogs (after flea related dermatitis). It is estimated to affect approximately 10% of the dog population.
Signs
Clinical signs manifest in most affected dogs between one and three years of age but can first become apparent from three months to seven years. Atopic dogs become itchy which often first occurs in the spring or summer months. Self-trauma rapidly leads to marked inflammation of skin, loss of hair, skin thickening and infection with bacteria and fungi. Commonly affected regions include the face, ears, paws, abdomen, chest, armpits and flanks.
Diagnosis
The diagnosis of atopy should begin with a thorough physical examination and history of the patient. It is important to rule out other causes of dermatitis such as food allergy or parasitic disease, for example, fleas and Sarcoptes mites.
Intradermal (skin) allergy testing can be performed to help confirm a diagnosis of atopy; however, this test must be performed by a specialist veterinary dermatologist.
Serological blood testing may be useful in helping to identify significant sources of allergen to assist managing cases but has some limitations with accuracy.
Treatment
In general, over 90% of atopic dogs can be satisfactorily controlled but almost never completely cured. It is a lifelong problem requiring lifelong management. Strategies to control itchy skin usually involve combining several different techniques and medications.
Desensitisation
Allergy vaccines are one of the only forms of therapy to prevent the allergic reaction rather than treating it once it has occurred. The treatment involves injecting the patient with small amounts of the allergen over several weeks. Boosters are required throughout life to maintain efficacy. Intradermal allergy testing must be performed by a specialist dermatologist to identify the problem allergens and create the appropriate vaccine for your dog.
Avoidance
Avoiding inhaling the allergens is often not possible or practical, however, environmental management strategies may be attempted to minimise common sources of allergens. Keeping your dog out of rooms during vacuuming and dusting will minimise dust mite exposure as will housing your pet in carpet free rooms and regularly washing their bedding. Pollens are difficult to avoid in spring and summer but it is advised to keep the lawn cut short and keep your dog away during mowing. If your dog is allowed access to inside the use of air conditioners may help.
Treat Aggravating Conditions
Good flea control is imperative as any dog with sensitive or itchy skin will be very badly impacted on by parasites. Flea washes, powders and collars are ineffective products. A monthly tablet (Comfortis) or monthly top spot (Advantage, Revolution) is necessary for all in-contact animals.
Secondary infections with bacteria or fungi may occur when the skin becomes damaged and traumatised. Your vet may recommend medicated washes or tablets to treat this complicating problem.
Antihistamines
Antihistamines may provide some relief to itchy dogs. Some dogs benefit from one type more than another so a trial of different antihistamines may be required. These medications have very little side effects and are very safe to use, however, they may not provide enough relief in very itchy dogs. Your vet may suggest combining these tablets with other therapies.
Cortisone Tablets
These medications are often very effective at bringing relief to atopic dogs. Short courses of these medications are unlikely to cause significant side effects; however, they are unacceptable for long term control of the disease due to the possibility for serious consequences such as diabetes mellitus and hyperadrenocorticism.
Topical Cortisone
Creams and sprays can be very useful in reducing itchiness particularly when applied to hairless areas such as the abdomen or underarms. As the drugs are not being administered systemically the side effects are minimised.
Cyclosporine
This drug is able to control itchy skin in up to 75% of atopic dogs. This medication does not have the same side effects as oral cortisone so may be used in those dogs dependent on cortisone to remain comfortable. Initially, daily medication is required for four to six weeks but 50% of dogs can then be controlled by dosing every second day.
Fatty Acid Supplementation
Omega three and six fatty acids act as a natural anti-inflammatory for the skin. Used as a daily supplement these natural products may reduce your pet’s dependence on medication. This supplement is available from the vets as a liquid supplement called Nutricoat.
If you have any questions regarding the information in this article, please contact us.