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The
Martha's Vineyard Times is a weekly publication.
March 3 - March 9, 2005 Edition
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VISITING
VET
The
hair of the dog
March 5, 2005
By
Michelle Gerhard Jasny, VMD
Tank is a little Boston Terrier who first came to my office at eight
months old. He had been licking his groin and developed a condition,
not serious but uncomfortable, called scrotal pyoderma. Topical medication
cleared the infection right up, but three months later he was back
with an itchy rash on his neck. This time the infection was deeper
and we opted for oral antibiotics, fatty acid supplements, and a teensy
bit of cortisone to calm down the inflammation and pruritus (the technical
term for itchiness). Three weeks later, Tank was back. What now? The
rash on his neck had cleared but he was losing hair on his belly and
the inside of his hind legs. He was almost completely bald on his
underside and the coat on his neck was also getting thin. Unlike the
other episodes, there was no evidence of infection. Tank wasn't pruritic.
In fact, his skin didn't look irritated at all. No bumps, no redness,
no dandruff. Just no hair.
Clients often complain that their animals are shedding excessively.
Usually their concern is unwarranted. As long as the skin looks healthy
and there are no bald spots, it's probably normal physiologic shedding.
You need a vacuum, not a vet. Alopecia is defined as the loss or lack
of hair, ranging from small, localized areas to complete baldness.
If there are patches where the hair is thin and a rough stubble when
you rub your hand over it, this is self-induced alopecia,
caused by the animal chewing out its own fur in response to itching
from allergies, parasites, or bacterial or fungal infections. Tank's
bald spots had no stubble. They were clearly not self-induced and
the hair loss was way beyond normal shedding. Bilaterally symmetrical
hair loss is often a symptom of endocrine abnormalities, such as an
underactive thyroid, adrenal gland disease, or sex hormone imbalance.
But Tank was very young to be experiencing any of these conditions,
and he was showing no other signs except hair loss. His healthy skin,
the symmetrical distribution of the hair loss, his young age, and
his purebred status sent up a little red flag. I went to my on-line
veterinary data base and punched in Boston Terrier Alopecia.
I browsed the results.
Causes of hair loss
Canine recurrent flank alopecia: a repeated seasonal hair loss on
the sides of the body, common in English Bulldogs, Airedales, and
boxers but occurring in many breeds. It may happen every year, every
few years, or only once. In our part of the world, most cases lose
their fur in the fall and re-grow in spring or summer, but some do
just the reverse. The bald areas will often have excessive pigmentation.
No one knows the cause, but it is suspected that there is some abnormal
response of the hair follicles on the flank to changing day length.
Interesting, but not Tank. Color Dilution Alopecia (CDA) and Black
Hair Follicular Dysplasia (BHFD) are two uncommon, inherited abnormalities
that are specifically associated with certain coat colors. In CDA,
most prevalent in blue or fawn Dobermans but reported in at least
11 different breeds, hair loss is confined to area of blue or fawn
colored coat. It occurs between three months and three years of age.
BHFD can begin as young as one month of age, manifested by hair loss
in the black portions of two- tone or three-tone coated dogs. It has
been reported in seven different breeds. Dogs with these syndromes
are prone to secondary bacterial infections and seborrhea. Other breeds,
including Irish Water spaniels, Bouviers, Staffordshire terriers,
miniature schnauzers, English springers, Chesapeake Bay retrievers,
Labrador retrievers, rottweilers, and French bulldogs, can be affected
by a variety of hair follicle abnormalities unrelated to coat color.
Siberian husky and Alaskan malamute pups may lose the long guard
hairs on their trunks, but not their heads or legs, leaving
them with a funny ruffed appearance. The texture of the fur may be
abnormal, with a reddish discoloration. Northern breed dogs are also
prone to a condition veterinarians hate, post-clipping alopecia. If
we shave an area on a samoyed, chow, malamute, or husky, the fur may
take a very long time to re-grow, as long as two years in some cases.
This is because these heavy-coated Northern dogs normally have a very
long hair cycle. Rather than shedding and re-growing a full coat every
year like dogs from more temperate climates, they shed their coats
less frequently, and their follicles remain in a quiescent state for
prolonged periods of time. Portuguese water dogs and curly-coated
retrievers have a syndrome, occurring between the ages of two and
four years in which they lose hair on their trunks. When, and if,
it re-grows, it often has an abnormal texture. All of these syndromes
result from abnormalities of the hair follicles and may be diagnosed
by a combination of clinical signs, breed, history, and skin biopsy
(which should be evaluated by a pathologist who is specially trained
in dermatological disorders).
Time for Rogaine?
Now I came to the section on Pattern Baldness. The hair follicles
of dogs with pattern baldness may be histalogically normal. They just
don't grow hair in specific regions. For example, pinnal alopecia
of dachshunds. I've seen that. They lose the hair on the ears, starting
at about a year of age. By the time they are middle-aged their ears
are bald and hyper-pigmented. Next. Ventral pattern alopecia. Typical
age of onset: six months. Tank was 11 months. Close enough. Usually
affecting the areas behind the ears, the entire belly from neck to
tail and the insides and backs of the thighs. Yup. Breeds most commonly
affected: dachshunds, chihuahuas. whippets, greyhounds, Italian greyhounds,
miniature pinschers, Manchester terriers and
drum roll
Boston terriers. Bingo! I did a little dance and went back to the
exam room.
Looks like Tank has ventral pattern alopecia! I informed
her, enthusiastically.
What's that? she asked. Well, it's this thing Boston
terriers can get, I began.
um
this condition,
you know, where they get bald
ventrally
that means underneath.
I paused. She looked at me expectantly. She didn't exactly say Duh,
but I suspect she was thinking it. What causes it? she
asked. Another pause.
It just happens, I replied, lamely. Ah, I
rallied, but I do know how to treat it!
Many of these syndromes are primarily cosmetic. They bother the person
looking at the dog more than they bother the dog, and sometimes simply
waiting is the answer, as with post-clipping alopecia and canine recurrent
flank alopecia. But we always want to try to improve the coat if possible.
Melatonin, a hormone produced by the pineal gland in the brain, is
naturally involved in the hair growth cycle, signaling the body to
respond to decreasing day length by growing a winter coat. You can
buy melatonin over the counter at any health food store and many dogs
with these conditions will respond to it well. The dose varies with
the size of the dog. Once hair has re-grown, you can attempt to wean
the dose down, but most dogs will lose hair again if you discontinue
it entirely. CDA and BHFD are the more difficult to treat, needing
antibiotics and medicated shampoos to treat the infections and seborrhea
that often develop. Sometimes a change in food can help, especially
eliminating soy. Sometimes using synthetic retinoids can promote hair
growth, but melatonin is the cornerstone of therapy for most of these
conditions. Now if your middle-aged mutt is covered with big itchy
hairless patches, please don't just go buy melatonin. Go to your veterinarian
for a diagnosis. The syndromes described above are not that common
and occur almost exclusively in young, purebred dogs. Your pruritic
mixed breed dog probably has fleas, mange, allergies, an underactive
thyroid, Cushing disease, Sertoli cell tumor, or something else, and
no amount of melatonin is going to help. Tank, however, was a classic
case of ventral pattern alopecia. Within three months of starting
his melatonin, he had a beautiful full coat. Ah, success.
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