Hair loss (alopecia) in rabbits
Esther van Praag, Ph.D.
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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.
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.
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 0,400 mg/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.
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.
Severe cases of fungal infection on skin, limbs and face
Neoplasia, skin cancer (melanoma, carcinoma, lymphoma)
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.
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.
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.
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.
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.