Hair loss (alopecia) in rabbits
Esther van Praag, Ph.D.
Warning: this file contains pictures that may be distressing
for some persons
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Multifocal
alopecia Fur mite Cheyletiella parasitovorax is most likely to be found on the
dorsum and neck of the rabbit, where it causes dandruff, seborrheic lesions
(lesions from abnormally increased secretion of fatty matter), and a pruritic
(itching) condition. Leporacarus gibbus is found mainly on the dorsum and
abdomen. Fur
mites can cause a hypersensitivity reaction. If the condition is severe,
alopecia is observed.
________________________________ Burrowing mite Wounds appear first on the lips and nose, later around the
head, neck, between toes, and sometimes around the genitalia. Mange leads to
heavy scratching and licking of the affected region by the rabbit. This leads
to alopecia (loss of fur). Often one can observe the secretion of a watery
stuff that forms crusts upon drying. Self-mutilation will lead to wounds and
secondary bacterial infection.
________________________________ Ear mite Itching ears, frequent shaking of the head, and scratching up to the
stage of automutilation. In the beginning, small,
tightly adherent skin scales appear deep in the ear canal and the earlobes
and are surrounded by alopecic (balding) regions. Those yellow-gray scales
can be rather thick; they carry large numbers of the parasite, mite feces,
skin cells, and blood. Aside the characteristic lesions on the ear, the ear mite Psoroptes
cuniculi has been observed to infest other regions of the body, more
particularly the ventral abdomen. A. Acar, A. Kurtede, K. Ural, C. Ç. Cingi,
M. Ç. Karakurum, B. B. Yagci, B. Sari. Turk.
J. Vet. Anim. Sci. 2007; 31(6): 423-425. An Ectopic Case of Psoroptes
cuniculi Infestation in a Pet Rabbit A 2-year-old female New Zealand rabbit was
admitted to Ankara University Veterinary Faculty, Department of Internal
Medicine. Upon physical examination crustaceous auricular lesions, and
erythematous and exudative pruritic skin lesions, both on the ventral abdomen
and on extremities were detected. Microscopic examination of skin scrapings
taken from pinnae and hair plucked from the ventral
abdominal region revealed the presence of Psoroptes cuniculi. The ventral
abdominal localization of P. cuniculi was evaluated as an ectopic
infestation. Despite the injection of ivermectin 400 μg/kg
and daily supportive therapy the rabbit died on the fifth day of
hospitalization.
Lesions on the rabbit. a)
Inner surface of the pinna; b) ventralabdomen
and extremities. ________________________________ Fleas and ticks The
presence of fleas is typically subclinical and seasonal. Infestation is characterized
by the presence of the feces of the fleas and their eggs at the periphery of
the ears, between them, on the eyelids or the nose of the rabbit. Other
locations on the body should nevertheless not be ruled out. In rare cases, a
strong allergic reaction against the saliva injected by the flea takes place.
The presence of Spilopsyllus cuniculi often leads to pruritic skin and
the appearance of crusts. Ticks are usually found while inspecting the fur of
a rabbit. Preferred locations are the ears, the area between the ears, the
neck and the dewlap of female rabbits. Severe infection can lead to macrocytosis. It can be accompanied by the development of
alopecia around the biting site. ________________________________ Bacterial dermatitis or presence of an
abscess Abscesses are typically found on the head, neck
and shoulders regions, but can also affect other parts of the body, organs or
bones. During palpation, abscesses feel either as a hard lump or a soft
doughy swelling that can be moved. The pocket contains a collection of pus,
dead phagocytic white blood cells, necrotic cells, and live or dead bacteria.
As the quantity of pus increases, the pocket grows larger and starts to wall
off from the surrounding tissues and blood circulation. If the abscess is
left untreated, it continues to grow till the tissue will rupture either
inside the body or on the surface of the skin. This stage is particularly
painful and dangerous, with the liberation of bacteria and their toxins in
the blood circulation. There are no specific clinical signs, except the
presence of a lump, an unusual swelling, reduced appetite, increased water
intake, or fever. The presence of an abscess is usually painless, unlike
other animals. In case of bacterial dermatitis, the use of corticosteroid based
creams should be avoided; they make the problem worse the problem.
________________________________ Fungal dermatitis Typically,
lesions start around the head and spread to the legs and feet, more
specifically to the toenail beds. The wound is raised, circumscribed and
erythematous. It shows dry crusts with little or no pruritus and patchy
alopecia. The tissue under the crusts usually shows inflammation and the hair
follicles show abscessation, as the secondary result of a bacterial invasion. Histological sections show hyperkeratosis, folliculitis, acanthosis and the diffuse infiltration of leukocytes
into the dermis layer.
Katleen Hermans Severe cases of fungal infection on skin, limbs and face ________________________________ Neoplasia, skin
cancer (melanoma, carcinoma, lymphoma)
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Symmetrical
bilateral alopecia Rarely,
symmetrical bilateral alopecia is observed in a rabbit. Due to the scarcity
of the cases, and few veterinary publications on this topic in rabbits, the
problem is often misdiagnosed.
Louise
Geddes In non-spayed
female rabbits, symmetrical
bilateral alopecia may be associated to a hormonal disorder caused
by ovarian diseases. In various animal species, hyperestrogenism
is accompanied by fur thinning in the urogenital region. The mammary glands
and vulva may appear swollen. If radiography does not show the presence of
tumors in other organs or lungs, an emergency ovariohysterectomy may
help the rabbit regain health. In one case, symmetrical bilateral alopecia has
been linked to thymoma, the growth of a benign tumor in the thymus gland,
located in the upper chest. The skin showed features typical of exfoliative
dermatitis and labored breathing. Florizoone K, van der Luer R, van den Ingh T. Symmetrical alopecia,
scaling and hepatitis in a rabbit. Vet Dermatol.
2007 Jun;18(3):161-4. A 5-year-old rabbit with inappetence, symmetrical
alopecia and skin lesions was examined. No mites or Malassezia were found in
skin scrapings and tape impressions and dermatophyte culture was negative.
Trial therapy with ivermectin did not reduce skin lesion severity, and
euthanasia was performed because of anorexia after 1 month. Histopathology of
the skin showed hyperkeratosis, lymphocytic exocytosis,
cell-poor interface dermatitis (lymphocytic infiltration and apoptotic cells
in basal layer of epidermis), absence of sebaceous glands and lymphocytic
mural folliculitis comparable to sebaceous adenitis and thymoma-associated
exfoliative dermatitis previously described in rabbits. The liver exhibited an interface hepatitis, comparable to autoimmune hepatitis
in man. The occurrence of morphological similarities to exfoliative
dermatitis and sebaceous adenitis in rabbits, in association with an
autoimmune hepatitis, has not been described before. In
some animal species, more so in ferrets, symmetrical bilateral alopecia has
been linked to adrenal disease in castrated animals. The alopecic skin
appeared normal in most seen ferrets. Adrenal disease is often accompanied by
increased sexual behavior and aggressiveness. In females, the vulva may
appear swollen.
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Congenital
alopecia - Hypotrichosis Juvenile hairlessness is a
condition where a young rabbit starts losing fur. It is a rare condition. The
fur either becomes thin, or hair is lost all over the body, except the tail,
the extremities of the limbs, the ears, the nasal
region. Fur may start to grow back after a few weeks. The cause of this
condition is not well understood. If the fur does not regrow with time,
the rabbit may suffer from a mutation that induced the loss of hair, and
leads to so called "furless rabbits". The condition is related to a mutation that is inherited
in a single recessive gene, making the condition very rare. Hair is rare and
limited to guard hair. The skin shows excessive keratinisation
(transformation into a more horny texture of the outer cells of the
epidermis). These rabbit are generally sensitive to cold temperature. Several
variations exist, some rabbits becoming fully furless, others growing only
one type of hair, e.g. only guard hair.
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Behavioral
alopecia Pseudopregnancy Female rabbits that are not spayed can go through cycles
of pseudopregnancy. It usually occurs after the rabbit has been mounted by a
castrated male or by a female rabbit in an attempt to establish dominance, an
act which simulates mating. It is also observed in rabbits living in
proximity to a non-castrated male or in an environment where there are no
other rabbits. Hair-pulling is indicative of the end of pseudopregnancy or
pregnancy period. Alopecic spots may form on the shoulders or abdomen, and
may be accompanied by injured and inflamed skin.
MediRabbit ________________________________ Self-mutilating behavior Some rabbits engage in self-mutilation to the point of
severe injury to themselves when it includes chewing the skin down to the
bone. Rather than diagnosing self-mutilation as a psychotic problem, possible
causes should be examined and ruled out when a rabbit shows this behavior.
Causes include: ·
Hypersensitive
reaction. This involves the immune system, and is difficult to assess. Such reaction
can be triggered by medication, e.g. intra-muscular injections of ketamine/xylazine can cause
skin irritation, 3 days post-injection. ·
Infestation of
the skin by parasites, such as fur mites, or burrowing mites. ·
Atopy,
or hereditary allergic reaction. ·
Frustration in
non-castrated female or male rabbits, driven by hormones to build a nest or
find a partner respectively. ·
Contact
dermatitis - inflammation of the skin or rash, caused by contact with an
irritating or allergy-causing substance. ·
Neurological
disease. ·
Presence of a
foreign body in the fur, e.g. seeds from grass, oat, burrs or awns
(bristle-like appendages found on grasses). Compulsive
self-mutilating behavior has additionally been linked to environmental factors
(e.g. boredom), and to genetic predisposition in specific breeds of rabbits.
These rabbits start to mutilate the pruritic skin of their digits, more
commonly in late summer and autumn (hormonal problem ?).
Histological studies ruled out the presence of skin disease, bacterial,
fungal or parasitic infection, or neurological problems. When genetic
predisposition is determined as the cause, the condition is treated with
psychotic drugs. F. Iglauer, C. Beig, J. Dimigen, S.
Gerold, A. Gocht, A. Seeburg, S. Steier and F. Willmann. Hereditary
compulsive self-mutilating behaviour in laboratory
rabbits. Lab Anim 1995;29:385-393 During
the last few years an increasing number of cases of extensive automutilation has been observed
in a rabbit breeding colony of Checkered crosses. Digits and pads of the
front feet were traumatized. No other behavioural
abnormalities or signs of disease were evident. Self-mutilation was seen both
in stock, breeding and experimental animals, in rabbits kept singly in cages
and in those housed in groups on the ground, in rabbits kept in different
buildings and under the care of different staff members. This behavioural abnormality of Checkered crosses has also
been observed in animals after being placed into other institutions or
private homes. No evidence of an agent responsible for the occurrence of
self-injury could be found with parasitological, mycological, histological,
clinical or haematological examination. Twelve to
16 animals are affected yearly in a colony varying in size between 130 and
230 rabbits. Following
complete healing, relapses occurred up to 3 times per year, on either the
same or the opposite front foot. In the last 21 cases episodes of automutilation could be regularly interrupted with the
dopamine antagonist, haloperidol. Similar signs of automutilation
were never seen in animals of another breeding line kept in the same building
and under the same conditions nor in animals brought in from other breeding
colonies. A relatively high coefficient of
inbreeding can be presupposed in this 15-year-old breeding colony of
Checkered crosses. A genetic predisposition for the behavioural
anomaly described appears very likely.
Fig
1A and B Lesions of digits and pads due to self-mutilation with increasing
degrees of severity . |
Many thanks
to Ils Vanderstaey (Belgium),
Berend Bakker (Indonesia), Louise Geddes (USA),
Christine Macey (USA), Dr. Kathleen Hermans (Kliniek voor Pluimvee
en Bijzondere Dieren,
Universiteit Gent, Belgium), Caroline van Mol (Bunnybunch.nl, Switzerland) and to Akira Yamanouchi (Veterinary
Exotic Information Network, Japan) for their help in providing pictures
to illustrate this page.
e-mail: info@medirabbit.com
