Overview of Canine Contact Dermatitis
Contact dermatitis is an uncommon skin disease of dogs caused by contact with plants (especially plants of the wandering Jew family), medications, and various chemicals. Contact dermatitis is not as common in animals as in people because the skin of dogs normally is protected by their hair coat. Contact dermatitis can develop, however, in areas of the body where the hair is sparse.
Contact dermatitis can be of two different types: allergic or irritant.
Contact allergy is a delayed reaction with signs occurring 24 to 48 hours after contact with the offending substance. The reaction is the same type that occurs in people who develop poison ivy.
Typical signs of contact allergy include pruritus (itchiness) and a papular eruption (red bumps). Pruritus can be severe. The paws and muzzle commonly are affected in animals, and sometimes, the insides of the ears are affected, especially in dogs with pendulous ears that come into contact with plants and grasses. In households with several animals, it is uncommon for more than one animal to develop an allergic reaction.
Irritant reactions are more painful than pruritic. Small vesicles (blisters) and ulcerations develop. The distribution of the lesions depends on the nature of the offending substance and the pattern of contact.
Secondary bacterial skin infections may develop due to trauma and inflammation.
What to Watch For
Diagnosis of Contact Dermatitis in Dogs
Treatment of Contact Dermatitis in Dogs
The treatment is to remove the dog from the offending substance.
If contact allergy is suspected, you may asked to confine your animal to a limited area of his normal environment to prevent contact with suspected substances. Confinement should start after a thorough bath, because small particles of the substance may remain on the skin and perpetuate clinical signs.
Compliance is very important. If plants are suspected, you may have to use specialized boots and T-shirts to protect your dog’s skin and walk the animal only on concrete areas until the lesions have healed, typically 10 to 14 days.
Bacterial skin infections occur commonly in dogs with contact allergy or irritant reactions. You may be asked to administer an antibiotic for a minimum of three to four weeks.
In severe cases, a course of anti-inflammatory medications such as prednisone may be necessary to make your pet more comfortable. Orally administered medications usually are safer than injectable preparations and should be used as a first choice. Adverse effects of this type of therapy include increased appetite, increased thirst and increased urinations. Avoidance of the offending allergen should be attempted whenever possible, because corticosteroids tend to lose their efficacy with repeated use. This is called tachyphylaxis.