- Email: [email protected]
Skin diseases of ferrets
Skin Diseases of Ferrets Susan A. KeUeher, DVM
It is important to recognize the most common disease processes that affect the integumentary system of the ferret so that a proper diagnosis and treatment of these diseases can be effected. Reviewed are the normal ferret skin anatomy and common pathologic conditions. Copyright 2002, Elsevier Science (USA). All
rights reserved. Key words: Ferret, skin disease, sebaceous glands, adrenal disease, mast cell tumors, sebaceous epitheliomas, squamous cell carcinomas, trauma, canine distemper virus, ectoparasites.
he n o r m a l anatomy of ferrets' skin a n d c o m m o n pathologic conditions are reviewed.
T
Normal Anatomy T h e ferret's skin is covered by fur that comprises a soft, short u n d e r c o a t and long, coarse guard h a i r s ) T h e skin itself is very thick a n d has m a n y sebaceous glands. These glands p r o d u c e secretions that give the ferret its natural, slightly musky odor.. T h e sebaceous glands are less active in spayed and n e u t e r e d ferrets. 2 Most pet ferrets in the United States are spayed or n e u t e r e d and have less o d o r than their n o n - n e u t e r e d counterparts. Ferrets do n o t have well-developed sweat glands. 3 This factor, c o m b i n e d with a n o r m a l ferret's thick hair coat, make t h e m less tolerant of high temperatures. Ferrets do not usually require bathing. In fact, excessive bathing can cause dry, pruritic skin. If an owners feels a n e e d to bathe t h e i r ferret because of o d o r or dander, a mild cat or ferret s h a m p o o is r e c o m m e n d e d . Bathing should not be m o r e f r e q u e n t than once a month. 4
From the Bfz)ward Avian and Exotic Animal Hospital, Pompano Beach, FL Address correspondence to Susan A. Kellehev; DVM, B*vward Avian and Exotic Animal Hospital, 611 N W 31st Ave Pompano Beach, FL 33069. Copyrigt~t 2002, Elsevier Science (USA). All righls ,~served. 1055-937X/02/1103-0004535. 00/0 doi:l O.1053/saep. 2002.123978
136
Disease Conditions Metabolic/Endocrine Problems During the b r e e d i n g season (March t h r o u g h August for females and D e c e m b e r t h r o u g h July for males), ferrets often e x p e r i e n c e a bilaterally symmetrical alopecia of the tail, p e r i n e u m , and inguinal area. 2 Although the cause is not yet determined, the alopecia is thought to be secondary responses of the pineal and adrenal glands to the photoperiod. 4 During this period sebaceous secretions can be seen accumulating on the skin. These secretions are most apparent on the tail. O n e of the m o s t c o m m o n skin presentations in ferrets is bilaterally symmetrical generalized alopecia. This is usually secondary to disease states of either or both of the adrenal glands. T h e adrenal cortex can b e c o m e cystic or hyperplastic or exhibit neoplastic changes (eg, an ade n o m a or an a d e n o c a r c i n o m a ) , in all of these states, the diseased adrenal tissue is typically functional and produces excessive amounts of androgenic hormones.
Diagnosis Diagnosis is based on history, findings of the physical examination, estradiol and a n d r o g e n h o r m o n e assay, a n d ultrasonography. T h e most c o m m o n findings are bilaterally symmetrical alopecia, lethargy, muscle atrophy, enlarged vulva in females, aggression, pruritis, male sexual behavior in castrated males, and stranguria. 5 Androgen h o r m o n e assays are carried out at the University of Tennessee College of Veterinary Medicine (Clinical Endocrinology D e p a r t m e n t , Knoxville, TN). T h e h o r m o n e s assayed for in this panel are estradiol, androstenedione, and 17-hydroxyprogesterone. Elevated levels of one or m o r e of these h o r m o n e s indicate hyperadrenocorticism. These h o r m o n e s are present in minute quantities in healthy n e u t e r e d ferrets. 6 For ultrasonography the left adrenal gland is located medial to the cranial pole of the left kidney, and the healthy left gland is approximately 6-8 m m in length. T h e right adrenal gland is located cranial to the cranial pole of the
Seminars in Avian and Exotic Pet Medicine, Vol 11, No 3 (July), 2002: pp 136-140
Skbz Diseases of Ferrets
right kidney a n d is covered by the caudate lobe of the liver. It is intimately associated with the caudal vena cava. T h e r e is a p r o m i n e n t gastric l y m p h n o d e in the same vertical plane as the right adrenal gland that can be easily mistaken for this gland. Care should be taken to follow the vena cava cranially f r o m the right kidney in order to locate the right adrenal gland. T h e healthy right adrenal gland is 8-11 m m in length. 4 T u m o r s involving either gland can range in size f r o m 1 to several centimeters in diameter. A d e n o c a r c i n o m a s can be locally aggressive and invade the caudal vena cava as well as the liver. O n any ferret presenting with clinical signs of adrenal disease, a c o m p l e t e b l o o d count, a chemistry panel, and a urinalysis should be run. It is not u n c o m m o n for ferrets with adrenal disease to have other disease states such as an insulinoma or other neoplasia. Treatment
T h e r a p y options for ferrets with diseased adrenal glands are surgical excision of the affected gland or medical m a n a g e m e n t with leuprolide acetate d e p o t (Lupron, TAP Pharmaceuticals, Deerfield, IL). Before attempting surgery, the clinician should b e c o m e familiar with the surgical technique u n d e r the guidance of a clinician who has d o n e the p r o c e d u r e before. T h e nonsurgical therapy of choice is treatm e n t with leuprolide acetate d e p o t injections. This drug is a synthetic long-acting gonadotrophin-releasing h o r m o n e analogue. In h u m a n subjects leuprolide acetate causes an initial stimulation and then suppression of the luteinizing and follicle-stimulating hormonesl This horm o n a l suppression inhibits the conversion of cholesterol to androgens and estradiol. Dr Cathy Johnson-Delaney has d o n e extensive work with L u p r o n for the t r e a t m e n t of adrenal disease in ferrets and has described h e r protocols in detail. 6 L u p r o n is available in 1-month or 4-month d e p o t formulations. Ferrets less than 1 kg seem to r e s p o n d well to 100/xg doses of the 1-month d e p o r t formulation given intramuscularly every 4-6 weeks( whereas larger animals benefit f r o m 200 /xg doses. 6 G o o d clinical response has also b e e n seen with the administration o f 2 m g o f the 4-month d e p o t formulation given intramuscularly once every 4-6 months. The 1-month for-
137
mulation has b e e n m o r e thoroughly researched. Although alleviation of clinical symptoms has b e e n observed for ferrets treated with this drug, clients should be advised that this is an extralabel and e x p e r i m e n t a l use of this drug.
Neoplastic Conditions Neoplastic conditions of the skin are the third most c o m m o n tumors seen in ferrets. 1 O f these, the most c o m m o n are sebaceous epitheliomas, mast cell tumors, and squamous cell carcinomas (Figs 1 and 2). 1,2 Diagnosis is based on physical examination, cytology, and histopathology. Sebaceous epitheliomas, which include sebaceous adenomas, can a p p e a r as warts, ulcerated masses, or cystic masses in the skin. 2 Diagnosis is m a d e by histopathology. T r e a t m e n t is complete surgical excision. Mast cell tumors are c o m p o s e d of well-differentiated mast cells. T h e y are similar in appearance to the cutaneous mastocytomas of domestic cats. 2 On physical examination, mast cell tumors range in size f r o m 2 m m to 1 cm in diameter. They can either be u n p i g m e n t e d or erythemic. A black exudate is often present. Diagnosis can be m a d e by fine-needle aspirate and cytology or histopathology. Cytologic examination frequently reveals m a t u r e mast cells. T r e a t m e n t is complete surgical excision. These masses do not tend to metastasize systemically and do not have to be removed, but they frequently cause pruritis
Figure 1. Classic appearance of a mast cell tumor on a ferret. Note the black exudate. (Reprinted with permission. 9)
138
Susan A. KeUeher
liotropic l y m p h o m a in a middle-aged, spayed female ferret. T h e ferret p r e s e n t e d with all 4 paws severely swollen. T h e skin was erythematous. T h e nails were malformed, a n d m a n y were missing (Fig 3). Diagnosis was m a d e by biopsy and histopathology. The ferret was treated with oral p r e d n i s o n e at 2.5 m g / k g orally every 12 hours and topical Panalog c r e a m (Ft. Dodge Labs, Ft. Dodge, IN). T h e ferret i m p r o v e d dramatically within 4 weeks of t r e a t m e n t (Fig 4). T h e animal lived comfortably for 6 m o n t h s postdiagnosis. It t h e n p r e s e n t e d with signs of advanced systemic l y m p h o m a and was euthanized.
Ectoparasites
Figure 2. Mast cell tumor on a ferret. Note the dark raised appearance. (Reprinted with permission. 9) a n d are irritating to the animal. T e m p o r a r y relief of the pruritis can be obtained by applying d i p h e n h y d r a m i n e hydrochloride (Benadryl, W a r n e r Lambert, Morris Plains, NJ) c r e a m to the lesion or by giving Benadryl syrup orally at a dose of 1 m g / l b orally every 8 hours. Squamous cell carcinomas are often firm a n d ulcerated. They can metastasize deep into the skin a n d regional lymph nodes. Surgical excision is the t r e a t m e n t of choice; however, recurrence can occur. C h e m o t h e r a p y has b e e n unsuccessfulY O t h e r neoplastic conditions of the skin that have b e e n r e p o r t e d in ferrets include adenocarcinomas of the perianal gland, sebaceous gland, and prepuce, basal cell carcinomas, a n d h e m a n giomas. 1 T h e author has seen a case of epithe-
Ferrets often b e c o m e infested with the comm o n flea, Ctenocephalidesfelis. 1 T r e a t m e n t should be directed at the e n v i r o n m e n t as well as the affected animal. Products that are safe for cats and kittens are generally considered to be safe for ferrets. These include pyrethrin sprays, 2 imidacloprid (Advantage, Bayer, Shawnee Mission, ItS) and selamectin (Revolution, Pfizer, Exton, PA). Because of the ferret's small size and g r o o m i n g habits, any topical p r o d u c t should be used with caution. O t h e r parasitic conditions e n c o u n t e r e d in pet ferrets include ear mites, scabies fur mites, and ticks. Ferrets are c o m m o n l y infected with the same ear mite as dogs and cats, Otodectes cynotis, 7 which are transmitted by direct contact with other infected animals. Clinical signs associated With ear mites include shaking of the h e a d and pruritis of the ears. A copious, dark brown exudate is c o m m o n l y seen. Microscopic examination of the exudate frequently reveals high n u m b e r s of live mites as well as eggs. To eliminate ear mite infestation in ferrets completely, aggressive therapy is needed. Ear mites
Figure 3. (A) and (B) Middle-aged, spayed female ferret with epitheliotropic lymphoma. All 4 paws were extremely swollen, the skin was etTthematous, and the nails were malformed with many missing. (Reprinted with permission. 9)
Shin Diseases of Ferrets
139
contact with the mite or a fomite. As with dogs and cats, this mite is difficult to locate by skin scrapings. It causes intense pruritis and focal-togeneralized alopecia. T r e a t m e n t consists of injections of ivermectin at a dosage of 0.2-0.4 m g / k g subcutaneously every 7-14 days until the mites are gone. Fur mites of the species Lynxacarus mustelae have been reported in ferrets. 8 Ferrets with this mite present with ulcerative lesions on the face. The ferrets are treated topically with a permethrin powder, and the e n v i r o n m e n t cleaned with a flea s h a m p o o containing permethrin. Ferrets can also b e c o m e infected with ticks. Treatment is by physical removal of the entire tick and application o f a dose o f Revolution.
Infectious Diseases Ferrets are susceptible to ringworm. Microspo"rum canis and Trichophyton mentagrophytes are the
Figure 4. (A) and (B) Same ferret as in Figure 3. Ferret improved dramatically within 4 weeks of treatment. (Reprinted with permission. 9)
can be particularly difficult to eliminate in multiferret households. Standard therapy consists of subcutaneous ivermectin injections at dosages of 0.2-0.4 m g / k g every 2 weeks for 3-4 treatments. 2 The owner must also clean the animals' ears gently and frequently, as well as launder any b e d d i n g the animals have contacted. Revolution, the Pfizer p r o d u c t containing selamectin, is proving to be more efficacious at resolving ear mite infestation problems. Revolution is advertised as a preventative for heartworms and intestinal parasites in cats, and as a flea, tick, and ear mite treatment for cats and dogs. Several ferret owners in the author's practice have now used the p r o d u c t to treat ear mites. No ill effects have been seen in these ferrets. A switch was made to this p r o d u c t because of frequent recurrent problems with ear mite infestations, even after treatment with ivermectin. Although it is not c o m m o n l y seen, ferrets also can b e c o m e infested with Sarcoptes scabiei. This is a zoonotic disease and is transmitted by direct
causative agents of ringworm in ferrets? O n physical examination, the lesions can appear as small papules that spread peripherally or that have progressed to large circumscribed areas of alopecia and inflammation over the entire body. O t h e r information that can lead the clinician to suspect ringworm is the presence of other animals or people in the household with skin lesions. Diagnosis is m a d e by fungal culture of the hair or skin. Samples should be taken from the periphery of the lesion. Treatment consists of shaving off the hair a r o u n d all of the lesions and treating the animal topically with keratolytic shampoos and antifungal medications such as miconazole c r e a m 2 Fungal infections should be considered in any cases of skin disease in ferrets that involve draining tracts or lack o f response to other therapy. O t h e r fungal infections that have been reported in ferrets include Blastomyces dermatitidis, Coccidioides, and Muco)~nycosis spp2 Ferrets are also susceptible to bacterial infections o f the skin. As in any other species, a culture and sensitivity of any infected lesion should be submitted and the appropriate antibiotics prescribed. The only c o m m o n viral disease of ferrets that affects the skin is canine distemper virus, a paramyxovirus. Transmission is by direct contact with infected animals, aerosol exposure, or contact with fomites2 The skin lesions include a
140
Susan A. KeUeher
characteristic erythematous rash under the chin, in t h e i n g u i n a l area, o r in t h e p e r i a n a l a r e a . T h e s e lesions a p p e a r w i t h i n 10-15 days o f e x p o sure. A g e n e r a l i z e d o r a n g e - t i n g e d d e r m a t i t i s as well as p r u r i t i s c a n b e seen. S w o l l e n eyelids a n d b r o w n crusts a p p e a r i n g a r o u n d the face, c h i n , a n d lips a r e a l s o d e r m a t o l o g i c e v i d e n c e o f can i n e d i s t e m p e r i n f e c t i o n in t h e ferret. 4 As also s e e n in dogs, t h e f o o t p a d s c a n b e c o m e swollen and hyperkeratotic. Antemortem diagnosis of d i s t e m p e r in a f e r r e t c a n b e difficult. S e r u m a n t i b o d y titers c a n b e r u n , a n d u n v a c c i n a t e d a n i m a l s s h o u l d n o t have a n t i b o d i e s to c a n i n e d i s t e m p e r . F l u o r e s c e n t a n t i b o d y tests for t h e p r e s e n c e o f t h e viral a n t i g e n in b l o o d s m e a r s a n d c o n j u n c t i v a l s c r a p i n g s c a n also b e h e l p f u l . C a n i n e d i s t e m p e r is fatal in ferrets, a n d a n y f e r r e t with a q u e s t i o n a b l e v a c c i n a t i o n h i s t o r y a n d a c o m b i n a t i o n o f t h e s e clinical signs s h o u l d b e strictly q u a r a n t i n e d .
Trauma B e c a u s e f e r r e t s a r e playful by n a t u r e , t h e y c a n easily inflict m i n o r b i t e w o u n d s a n d s c r a t c h e s o n o n e a n o t h e r . S u p e r f i c i a l w o u n d s c a n also b e self-inflicted s e c o n d a r y to o t h e r d i s e a s e p r o cesses t h a t cause pruritis: W o u n d s s h o u l d b e c l i p p e d , c l e a n e d , a n d t r e a t e d with a t o p i c a l ant i m i c r o b i a l m e d i c a t i o n as i n d i c a t e d . Understanding the normal anatomy and p h y s i o l o g y o f t h e skin o f a f e r r e t is i m p o r t a n t b e c a u s e t h e r e a r e m a n y disease entities c o m m o n to t h e f e r r e t t h a t m a n i f e s t as c u t a n e o u s lesions. C a r e f u l e x a m i n a t i o n o f t h e skin o f a f e r r e t d u r ing a regular physical examination can reveal a
s i n g u l a r disease p r o c e s s s u c h as a n e o p l a s m o r the presence of ectoparasites. O t h e r physical e x a m i n a t i o n f i n d i n g s s u c h as a l o p e c i a , pruritis, o r r a s h c a n b e i n d i c a t i v e o f m u c h m o r e s e r i o u s systemic diseases. F e r r e t s with systemic diseases s u c h as a d r e n a l disease o f t e n a r e b r o u g h t to t h e c l i n i c i a n solely f o r t h e evaluation of the cutaneous manifestation of the disease, C l i n i c i a n s m u s t r e c o g n i z e t h e m o s t c o m m o n disease p r o c e s s e s t h a t affect the i n t e g u m e n t a r y system o f t h e f e r r e t so t h a t t h e y c a n pursue the proper diagnosis and treatment of t h e s e diseases.
References 1. Fox JG: Biology and Diseases of the Ferret. Philadelphia, PA, Lea & Febiger, 1988 2. Orcutt CJ, Dermatologic diseases, in Hillyer E, QuesenbertT E (eds): Ferrets, Rabbits, and Rodents: Clinical Medicine and Surgery. Philadelphia, PA, Saunders, 1997, p 116 3. Ivey E, MorrisseyJ: Ferrets: Examination and preventive medicine. Vet Clin North Am Exotic Anim Pract 2:471494, 1999 4. Brown SA: Commonly encountered non-neoplastic disorders of the domestic ferret. Proc Atlantic Coast Vet Conf, Atlantic City, NJ, October, 1993 5. Weiss CA, Scott MV: Clinical aspects and surgical treatment of hyperadrenocorticism in the domestic ferret: 94 Cases (1994-1996). J Am Anim Hosp Assoc 33:487-493, 1997 6. Johnson-Delaney C: Ferret adrenal disease: Alternatives to surgmT. Exotic DVM 1:19-22, 1999 7. Georgi JR, Georgi ME: Parasitology for Veterinarians. Philadelphia, PA, Saunders, 1990 8. Shoemaker NJ: Selected dermatologic conditions in exotic pets. Exotic DVM 1:5-12, 1999 9. Kelleher SA: Skin diseases of ferrets. Veterinary Clin North Am Exot Anita Pract 4:565-572, 2001
It is important to recognize the most common disease processes that affect the integumentary system of the ferret so that a proper diagnosis and treatment of these diseases can be effected. Reviewed are the normal ferret skin anatomy and common pathologic conditions. Copyright 2002, Elsevier Science (USA). All
rights reserved. Key words: Ferret, skin disease, sebaceous glands, adrenal disease, mast cell tumors, sebaceous epitheliomas, squamous cell carcinomas, trauma, canine distemper virus, ectoparasites.
he n o r m a l anatomy of ferrets' skin a n d c o m m o n pathologic conditions are reviewed.
T
Normal Anatomy T h e ferret's skin is covered by fur that comprises a soft, short u n d e r c o a t and long, coarse guard h a i r s ) T h e skin itself is very thick a n d has m a n y sebaceous glands. These glands p r o d u c e secretions that give the ferret its natural, slightly musky odor.. T h e sebaceous glands are less active in spayed and n e u t e r e d ferrets. 2 Most pet ferrets in the United States are spayed or n e u t e r e d and have less o d o r than their n o n - n e u t e r e d counterparts. Ferrets do n o t have well-developed sweat glands. 3 This factor, c o m b i n e d with a n o r m a l ferret's thick hair coat, make t h e m less tolerant of high temperatures. Ferrets do not usually require bathing. In fact, excessive bathing can cause dry, pruritic skin. If an owners feels a n e e d to bathe t h e i r ferret because of o d o r or dander, a mild cat or ferret s h a m p o o is r e c o m m e n d e d . Bathing should not be m o r e f r e q u e n t than once a month. 4
From the Bfz)ward Avian and Exotic Animal Hospital, Pompano Beach, FL Address correspondence to Susan A. Kellehev; DVM, B*vward Avian and Exotic Animal Hospital, 611 N W 31st Ave Pompano Beach, FL 33069. Copyrigt~t 2002, Elsevier Science (USA). All righls ,~served. 1055-937X/02/1103-0004535. 00/0 doi:l O.1053/saep. 2002.123978
136
Disease Conditions Metabolic/Endocrine Problems During the b r e e d i n g season (March t h r o u g h August for females and D e c e m b e r t h r o u g h July for males), ferrets often e x p e r i e n c e a bilaterally symmetrical alopecia of the tail, p e r i n e u m , and inguinal area. 2 Although the cause is not yet determined, the alopecia is thought to be secondary responses of the pineal and adrenal glands to the photoperiod. 4 During this period sebaceous secretions can be seen accumulating on the skin. These secretions are most apparent on the tail. O n e of the m o s t c o m m o n skin presentations in ferrets is bilaterally symmetrical generalized alopecia. This is usually secondary to disease states of either or both of the adrenal glands. T h e adrenal cortex can b e c o m e cystic or hyperplastic or exhibit neoplastic changes (eg, an ade n o m a or an a d e n o c a r c i n o m a ) , in all of these states, the diseased adrenal tissue is typically functional and produces excessive amounts of androgenic hormones.
Diagnosis Diagnosis is based on history, findings of the physical examination, estradiol and a n d r o g e n h o r m o n e assay, a n d ultrasonography. T h e most c o m m o n findings are bilaterally symmetrical alopecia, lethargy, muscle atrophy, enlarged vulva in females, aggression, pruritis, male sexual behavior in castrated males, and stranguria. 5 Androgen h o r m o n e assays are carried out at the University of Tennessee College of Veterinary Medicine (Clinical Endocrinology D e p a r t m e n t , Knoxville, TN). T h e h o r m o n e s assayed for in this panel are estradiol, androstenedione, and 17-hydroxyprogesterone. Elevated levels of one or m o r e of these h o r m o n e s indicate hyperadrenocorticism. These h o r m o n e s are present in minute quantities in healthy n e u t e r e d ferrets. 6 For ultrasonography the left adrenal gland is located medial to the cranial pole of the left kidney, and the healthy left gland is approximately 6-8 m m in length. T h e right adrenal gland is located cranial to the cranial pole of the
Seminars in Avian and Exotic Pet Medicine, Vol 11, No 3 (July), 2002: pp 136-140
Skbz Diseases of Ferrets
right kidney a n d is covered by the caudate lobe of the liver. It is intimately associated with the caudal vena cava. T h e r e is a p r o m i n e n t gastric l y m p h n o d e in the same vertical plane as the right adrenal gland that can be easily mistaken for this gland. Care should be taken to follow the vena cava cranially f r o m the right kidney in order to locate the right adrenal gland. T h e healthy right adrenal gland is 8-11 m m in length. 4 T u m o r s involving either gland can range in size f r o m 1 to several centimeters in diameter. A d e n o c a r c i n o m a s can be locally aggressive and invade the caudal vena cava as well as the liver. O n any ferret presenting with clinical signs of adrenal disease, a c o m p l e t e b l o o d count, a chemistry panel, and a urinalysis should be run. It is not u n c o m m o n for ferrets with adrenal disease to have other disease states such as an insulinoma or other neoplasia. Treatment
T h e r a p y options for ferrets with diseased adrenal glands are surgical excision of the affected gland or medical m a n a g e m e n t with leuprolide acetate d e p o t (Lupron, TAP Pharmaceuticals, Deerfield, IL). Before attempting surgery, the clinician should b e c o m e familiar with the surgical technique u n d e r the guidance of a clinician who has d o n e the p r o c e d u r e before. T h e nonsurgical therapy of choice is treatm e n t with leuprolide acetate d e p o t injections. This drug is a synthetic long-acting gonadotrophin-releasing h o r m o n e analogue. In h u m a n subjects leuprolide acetate causes an initial stimulation and then suppression of the luteinizing and follicle-stimulating hormonesl This horm o n a l suppression inhibits the conversion of cholesterol to androgens and estradiol. Dr Cathy Johnson-Delaney has d o n e extensive work with L u p r o n for the t r e a t m e n t of adrenal disease in ferrets and has described h e r protocols in detail. 6 L u p r o n is available in 1-month or 4-month d e p o t formulations. Ferrets less than 1 kg seem to r e s p o n d well to 100/xg doses of the 1-month d e p o r t formulation given intramuscularly every 4-6 weeks( whereas larger animals benefit f r o m 200 /xg doses. 6 G o o d clinical response has also b e e n seen with the administration o f 2 m g o f the 4-month d e p o t formulation given intramuscularly once every 4-6 months. The 1-month for-
137
mulation has b e e n m o r e thoroughly researched. Although alleviation of clinical symptoms has b e e n observed for ferrets treated with this drug, clients should be advised that this is an extralabel and e x p e r i m e n t a l use of this drug.
Neoplastic Conditions Neoplastic conditions of the skin are the third most c o m m o n tumors seen in ferrets. 1 O f these, the most c o m m o n are sebaceous epitheliomas, mast cell tumors, and squamous cell carcinomas (Figs 1 and 2). 1,2 Diagnosis is based on physical examination, cytology, and histopathology. Sebaceous epitheliomas, which include sebaceous adenomas, can a p p e a r as warts, ulcerated masses, or cystic masses in the skin. 2 Diagnosis is m a d e by histopathology. T r e a t m e n t is complete surgical excision. Mast cell tumors are c o m p o s e d of well-differentiated mast cells. T h e y are similar in appearance to the cutaneous mastocytomas of domestic cats. 2 On physical examination, mast cell tumors range in size f r o m 2 m m to 1 cm in diameter. They can either be u n p i g m e n t e d or erythemic. A black exudate is often present. Diagnosis can be m a d e by fine-needle aspirate and cytology or histopathology. Cytologic examination frequently reveals m a t u r e mast cells. T r e a t m e n t is complete surgical excision. These masses do not tend to metastasize systemically and do not have to be removed, but they frequently cause pruritis
Figure 1. Classic appearance of a mast cell tumor on a ferret. Note the black exudate. (Reprinted with permission. 9)
138
Susan A. KeUeher
liotropic l y m p h o m a in a middle-aged, spayed female ferret. T h e ferret p r e s e n t e d with all 4 paws severely swollen. T h e skin was erythematous. T h e nails were malformed, a n d m a n y were missing (Fig 3). Diagnosis was m a d e by biopsy and histopathology. The ferret was treated with oral p r e d n i s o n e at 2.5 m g / k g orally every 12 hours and topical Panalog c r e a m (Ft. Dodge Labs, Ft. Dodge, IN). T h e ferret i m p r o v e d dramatically within 4 weeks of t r e a t m e n t (Fig 4). T h e animal lived comfortably for 6 m o n t h s postdiagnosis. It t h e n p r e s e n t e d with signs of advanced systemic l y m p h o m a and was euthanized.
Ectoparasites
Figure 2. Mast cell tumor on a ferret. Note the dark raised appearance. (Reprinted with permission. 9) a n d are irritating to the animal. T e m p o r a r y relief of the pruritis can be obtained by applying d i p h e n h y d r a m i n e hydrochloride (Benadryl, W a r n e r Lambert, Morris Plains, NJ) c r e a m to the lesion or by giving Benadryl syrup orally at a dose of 1 m g / l b orally every 8 hours. Squamous cell carcinomas are often firm a n d ulcerated. They can metastasize deep into the skin a n d regional lymph nodes. Surgical excision is the t r e a t m e n t of choice; however, recurrence can occur. C h e m o t h e r a p y has b e e n unsuccessfulY O t h e r neoplastic conditions of the skin that have b e e n r e p o r t e d in ferrets include adenocarcinomas of the perianal gland, sebaceous gland, and prepuce, basal cell carcinomas, a n d h e m a n giomas. 1 T h e author has seen a case of epithe-
Ferrets often b e c o m e infested with the comm o n flea, Ctenocephalidesfelis. 1 T r e a t m e n t should be directed at the e n v i r o n m e n t as well as the affected animal. Products that are safe for cats and kittens are generally considered to be safe for ferrets. These include pyrethrin sprays, 2 imidacloprid (Advantage, Bayer, Shawnee Mission, ItS) and selamectin (Revolution, Pfizer, Exton, PA). Because of the ferret's small size and g r o o m i n g habits, any topical p r o d u c t should be used with caution. O t h e r parasitic conditions e n c o u n t e r e d in pet ferrets include ear mites, scabies fur mites, and ticks. Ferrets are c o m m o n l y infected with the same ear mite as dogs and cats, Otodectes cynotis, 7 which are transmitted by direct contact with other infected animals. Clinical signs associated With ear mites include shaking of the h e a d and pruritis of the ears. A copious, dark brown exudate is c o m m o n l y seen. Microscopic examination of the exudate frequently reveals high n u m b e r s of live mites as well as eggs. To eliminate ear mite infestation in ferrets completely, aggressive therapy is needed. Ear mites
Figure 3. (A) and (B) Middle-aged, spayed female ferret with epitheliotropic lymphoma. All 4 paws were extremely swollen, the skin was etTthematous, and the nails were malformed with many missing. (Reprinted with permission. 9)
Shin Diseases of Ferrets
139
contact with the mite or a fomite. As with dogs and cats, this mite is difficult to locate by skin scrapings. It causes intense pruritis and focal-togeneralized alopecia. T r e a t m e n t consists of injections of ivermectin at a dosage of 0.2-0.4 m g / k g subcutaneously every 7-14 days until the mites are gone. Fur mites of the species Lynxacarus mustelae have been reported in ferrets. 8 Ferrets with this mite present with ulcerative lesions on the face. The ferrets are treated topically with a permethrin powder, and the e n v i r o n m e n t cleaned with a flea s h a m p o o containing permethrin. Ferrets can also b e c o m e infected with ticks. Treatment is by physical removal of the entire tick and application o f a dose o f Revolution.
Infectious Diseases Ferrets are susceptible to ringworm. Microspo"rum canis and Trichophyton mentagrophytes are the
Figure 4. (A) and (B) Same ferret as in Figure 3. Ferret improved dramatically within 4 weeks of treatment. (Reprinted with permission. 9)
can be particularly difficult to eliminate in multiferret households. Standard therapy consists of subcutaneous ivermectin injections at dosages of 0.2-0.4 m g / k g every 2 weeks for 3-4 treatments. 2 The owner must also clean the animals' ears gently and frequently, as well as launder any b e d d i n g the animals have contacted. Revolution, the Pfizer p r o d u c t containing selamectin, is proving to be more efficacious at resolving ear mite infestation problems. Revolution is advertised as a preventative for heartworms and intestinal parasites in cats, and as a flea, tick, and ear mite treatment for cats and dogs. Several ferret owners in the author's practice have now used the p r o d u c t to treat ear mites. No ill effects have been seen in these ferrets. A switch was made to this p r o d u c t because of frequent recurrent problems with ear mite infestations, even after treatment with ivermectin. Although it is not c o m m o n l y seen, ferrets also can b e c o m e infested with Sarcoptes scabiei. This is a zoonotic disease and is transmitted by direct
causative agents of ringworm in ferrets? O n physical examination, the lesions can appear as small papules that spread peripherally or that have progressed to large circumscribed areas of alopecia and inflammation over the entire body. O t h e r information that can lead the clinician to suspect ringworm is the presence of other animals or people in the household with skin lesions. Diagnosis is m a d e by fungal culture of the hair or skin. Samples should be taken from the periphery of the lesion. Treatment consists of shaving off the hair a r o u n d all of the lesions and treating the animal topically with keratolytic shampoos and antifungal medications such as miconazole c r e a m 2 Fungal infections should be considered in any cases of skin disease in ferrets that involve draining tracts or lack o f response to other therapy. O t h e r fungal infections that have been reported in ferrets include Blastomyces dermatitidis, Coccidioides, and Muco)~nycosis spp2 Ferrets are also susceptible to bacterial infections o f the skin. As in any other species, a culture and sensitivity of any infected lesion should be submitted and the appropriate antibiotics prescribed. The only c o m m o n viral disease of ferrets that affects the skin is canine distemper virus, a paramyxovirus. Transmission is by direct contact with infected animals, aerosol exposure, or contact with fomites2 The skin lesions include a
140
Susan A. KeUeher
characteristic erythematous rash under the chin, in t h e i n g u i n a l area, o r in t h e p e r i a n a l a r e a . T h e s e lesions a p p e a r w i t h i n 10-15 days o f e x p o sure. A g e n e r a l i z e d o r a n g e - t i n g e d d e r m a t i t i s as well as p r u r i t i s c a n b e seen. S w o l l e n eyelids a n d b r o w n crusts a p p e a r i n g a r o u n d the face, c h i n , a n d lips a r e a l s o d e r m a t o l o g i c e v i d e n c e o f can i n e d i s t e m p e r i n f e c t i o n in t h e ferret. 4 As also s e e n in dogs, t h e f o o t p a d s c a n b e c o m e swollen and hyperkeratotic. Antemortem diagnosis of d i s t e m p e r in a f e r r e t c a n b e difficult. S e r u m a n t i b o d y titers c a n b e r u n , a n d u n v a c c i n a t e d a n i m a l s s h o u l d n o t have a n t i b o d i e s to c a n i n e d i s t e m p e r . F l u o r e s c e n t a n t i b o d y tests for t h e p r e s e n c e o f t h e viral a n t i g e n in b l o o d s m e a r s a n d c o n j u n c t i v a l s c r a p i n g s c a n also b e h e l p f u l . C a n i n e d i s t e m p e r is fatal in ferrets, a n d a n y f e r r e t with a q u e s t i o n a b l e v a c c i n a t i o n h i s t o r y a n d a c o m b i n a t i o n o f t h e s e clinical signs s h o u l d b e strictly q u a r a n t i n e d .
Trauma B e c a u s e f e r r e t s a r e playful by n a t u r e , t h e y c a n easily inflict m i n o r b i t e w o u n d s a n d s c r a t c h e s o n o n e a n o t h e r . S u p e r f i c i a l w o u n d s c a n also b e self-inflicted s e c o n d a r y to o t h e r d i s e a s e p r o cesses t h a t cause pruritis: W o u n d s s h o u l d b e c l i p p e d , c l e a n e d , a n d t r e a t e d with a t o p i c a l ant i m i c r o b i a l m e d i c a t i o n as i n d i c a t e d . Understanding the normal anatomy and p h y s i o l o g y o f t h e skin o f a f e r r e t is i m p o r t a n t b e c a u s e t h e r e a r e m a n y disease entities c o m m o n to t h e f e r r e t t h a t m a n i f e s t as c u t a n e o u s lesions. C a r e f u l e x a m i n a t i o n o f t h e skin o f a f e r r e t d u r ing a regular physical examination can reveal a
s i n g u l a r disease p r o c e s s s u c h as a n e o p l a s m o r the presence of ectoparasites. O t h e r physical e x a m i n a t i o n f i n d i n g s s u c h as a l o p e c i a , pruritis, o r r a s h c a n b e i n d i c a t i v e o f m u c h m o r e s e r i o u s systemic diseases. F e r r e t s with systemic diseases s u c h as a d r e n a l disease o f t e n a r e b r o u g h t to t h e c l i n i c i a n solely f o r t h e evaluation of the cutaneous manifestation of the disease, C l i n i c i a n s m u s t r e c o g n i z e t h e m o s t c o m m o n disease p r o c e s s e s t h a t affect the i n t e g u m e n t a r y system o f t h e f e r r e t so t h a t t h e y c a n pursue the proper diagnosis and treatment of t h e s e diseases.
References 1. Fox JG: Biology and Diseases of the Ferret. Philadelphia, PA, Lea & Febiger, 1988 2. Orcutt CJ, Dermatologic diseases, in Hillyer E, QuesenbertT E (eds): Ferrets, Rabbits, and Rodents: Clinical Medicine and Surgery. Philadelphia, PA, Saunders, 1997, p 116 3. Ivey E, MorrisseyJ: Ferrets: Examination and preventive medicine. Vet Clin North Am Exotic Anim Pract 2:471494, 1999 4. Brown SA: Commonly encountered non-neoplastic disorders of the domestic ferret. Proc Atlantic Coast Vet Conf, Atlantic City, NJ, October, 1993 5. Weiss CA, Scott MV: Clinical aspects and surgical treatment of hyperadrenocorticism in the domestic ferret: 94 Cases (1994-1996). J Am Anim Hosp Assoc 33:487-493, 1997 6. Johnson-Delaney C: Ferret adrenal disease: Alternatives to surgmT. Exotic DVM 1:19-22, 1999 7. Georgi JR, Georgi ME: Parasitology for Veterinarians. Philadelphia, PA, Saunders, 1990 8. Shoemaker NJ: Selected dermatologic conditions in exotic pets. Exotic DVM 1:5-12, 1999 9. Kelleher SA: Skin diseases of ferrets. Veterinary Clin North Am Exot Anita Pract 4:565-572, 2001