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,
Kliniek voor Pluimvee en Bijzondere Dieren, Universiteit Gent, Belgie 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.
Picture:
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.
________________________________ 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, Berend Bakker, Louise Geddes, Christine Macey, Dr. Kathleen
Hermans and to Caroline van Mol (Bunnybunch.nl)
for their help in providing pictures to illustrate this page.
e-mail: info@medirabbit.com
