Uses
Alone
- Identify potentially important allergens in order to start immunotherapy once a diagnosis of atopy
has been made.
In combination
- Diagnosis of atopy in cats with compatible history, clinical signs and laboratory tests that do not support other differential diagnoses.
- To identify allergens involved in atopy before attempting specific avoidance (however avoidance is rarely practical in cats).
Other points
Only undertake intradermal testing if animal owner is willing to commit to at least 1 year of hyposensitization treatment if test confirms diagnosis of atopy.
Result data
Normal (reference) values
- Generally: a wheal smaller than the mean size of those produced by positive and negative controls is considered negative.
Abnormal values
- Positive reactions result in a wheal and/or flare.
- A positive reaction in the cat may be subtle or transient and may be manifest as a brief flare (erythema) at the injection site.
Skin tests can be difficult to read in cats. - A wheal >the mean of those produced by positive and negative controls is considered positive.
- Subjective considerations include: induration, erythema and steepness of the wall of the wheal.
- A positive intradermal skin test is one in which there are many positive reactions to allergens that are compatible with the patient's history and seasonality of pruritus.
Errors and Artifacts
- Drug interference.
- Irritable, inflamed or traumatized skin.
- Stress, pregnancy and serious internal disease.
- Poor skin test technique.
- Outdated extract.
Sources
Publications
Refereed papers
- Chalmers S A & Medleau L (1994) Feline atopic dermatitis. Its diagnosis and treatment. Vet Med 89, 342.
- Foster A P & O'Dair H (1993) Allergy testing for skin disease in the cat. In vivo vs in vitro tests. Vet Dermatol 4, 111.
- McDougal B J (1986) Allergy testing and hyposensitization for three common feline dermatoses. Mod Vet Pract 67, 629.
- Reedy L M (1982) Results of allergy testing and hyposensitization in selected feline skin diseases. JAAHA 18, 618.
Other sources of information
- Reedy L M, Miller W H & Willemse J R (1997) Allergic skin diseases of dogs and cats. 2nd edn. Philadelphia: W B Saunders. pp 103-109. (Detailed procedure and interpretation.)
- Moriello K A & Mason I S (1995) Handbook of Small Animal Dermatology. Eds K A Moriello & I S Mason. 1st edn. Pergamon. pp 33-36. (Concise step-by-step procedure.)
- Scott D W, Miller W H & Griffin C (1995) Miller and Kirk's Small Animal Dermatology. Eds D W Scott, W H Miller & C Griffin. 5th edn. Philadelphia: W B Saunders Co. (Concise step-by-step procedure).
- Chalmers S et al (1991) Clinical evaluation of intradermal skin testing in cats. Proc Assoc Vet Allergy. West Palm Beach, FL, USA. p14.
