It has been my experience that most autoimmune skin diseases in the dog and cat are usually chronic. With this in mind, it
seems prudent to include in the initial or early stages of treatment an additional safer drug or drugs given concurrently
with corticosteroids. This allows the eventual taper and cessation of the corticosteroid therapy sooner, rather than later.
Example 1: A 3-year-old Chow-mix with histologically confirmed facial pemphigus foliaceus is waiting in your exam room. (Note: pemphigus
foliaceus is the most common autoimmune skin disease in the dog and cat.)
Initial therapy includes immunosuppressive dosages of prednisone given along with azathioprine. The beneficial effect of azathioprine
can have a lag period of up to three to four weeks. As the dog improves, the prednisone therapy is slowly tapered over four
to six weeks, and the azathioprine is continued. The goal would be to cease all drugs if lesions have completely resolved,
however, azathioprine given alone (in my opinion) is much safer and healthier for long-term management.
Flea control with flea allergies
One of the most common reasons for "failure" of topical adulticide therapy is neglecting to treat the environment (house and
yard). In a previous article in this magazine, I outlined the specifics about treatment for a flea infestation. In a nutshell,
treatment of the house and possibly the yard is crucial in breaking the life cycle of the flea. The majority of the life cycle
exists in the environment (eggs, larvae and pupae), so it does make perfect sense to focus most of our attention on treatment
of the environment.
There are several home treatments available, but I prefer products that at least contain insect grow regulators (IGRs). These
ingredients include methoprene (Precor) or pyriproxyfen (Nylar). These interfere with egg and larval development but do absolutely
nothing to adult fleas or pupae (cocoon). Most products, however, contain adulticides such as permethrins, and these can enhance
the effect of the IGRs.
Protocol for active infestation
For an active flea infestation, treat all animals with a veterinary adulticide (Advantage, Frontline or Revolution) at least
monthly. In some cases, I recommend applying some of these products every two to three weeks.
Home: Vacuum (with beater bar) every three days for four weeks. Spray house (and automobile) with a product that contains
an IGR (such as Vet-Kem Siphotrol Area Spray or Virbac's Knockout Spray) by spraying all carpeted areas, door mats, cat-scratch
towers, under the sofa cushions, pet bedding, hardwood floors (the cracks can harbor eggs and larvae) once, repeat in two
weeks, then again in three months. The reason for the re-application is the pupal stage is not affected by the sprays and
re-emerge in several weeks. The adulticide component allows a quick knockdown of newly emerging adult fleas from their cocoons.
Yard: Spraying the yard with a biologic spray (nematode) every two to three months. This has been shown to be very effective
and environmentally friendly. Some people advocate the use of malathion or diazinon, but it appears that these products (at
least in California) may be removed from the market. In addition, these products are not acceptable, in my opinion, as they
do more harm to beneficial insects.
Choosing to perform a skin biopsy
As the years go by, I find myself performing skin biopsies less frequently. I hope this is because I am more knowledgeable
and more experienced! Here are the special do's and dont's concerning skin biopsies in the dog and cat.
Most pruritic animals tend to be allergic, so a biopsy will not give any more information than you already know. Biopsy results
from these animals tend to be unrewarding in terms of eluding to the exact cause, but generally support your clinical diagnosis
of allergy. The results of biopsies from these patients can occasionally reveal evidence of self-trauma (pruritus) that may
be useful in cases (especially cats) where the history did not support pruritus. Concentrate on the distribution of the pruritus,
which I think is much more important and allows the initiation of a proper treatment plan.