Autoimmune diseases affecting skin melanocytes in dogs, cats and horses: vitiligo and the uveodermatological syndrome: a comprehensive review

Autoimmune dermatoses targeting melanocytes have gained attention in human medicine due to their progressive nature and the social impact suffered by affected individuals. In veterinary medicine, vitiligo and the uveodermatological syndrome are the two autoimmune diseases that are known to affect skin melanocytes.In the first part of this article, we will review the signalment, clinical signs, histopathology and the treatment outcome of vitiligo in dogs, cats and horses; where pertinent, we compare the animal diseases to their human homologue. In a similar fashion, the information on the uveodermatological syndrome in dogs is reviewed and, where relevant, it is compared to the Vogt-Koyanagi-Harada (VKH) syndrome in humans.Canine, feline and equine vitiligo have many features that mirror their human counterparts. The most effective treatment and outcome of vitiligo in animals remain unclear. The canine uveodermatological syndrome resembles the incomplete VKH variant in humans; for affected individuals, an immediate diagnosis and aggressive treatment are crucial to prevent the development of blindness.

Uveodermatologic syndrome concurrent with keratoconjunctivitis sicca in a miniature poodle dog

A 5-year-old, intact female miniature poodle dog was presented with chronic ophthalmic problems, facial poliosis, nasal depigmentation and multiple areas of alopecia over the trunk. Bilateral uveitis preceded dermatologic signs by 5 months and gradually worsened. The dog was diagnosed as having uveodermatologic syndrome (UDS) concurrent with keratoconjunctivitis sicca (KCS). Treatment with immunosuppressive drugs resolved the dermatologic lesions, but uveitis continued to progress.

Lateral line depigmentation (LLD) in channel catfish, Ictalurus punctatus (Rafinesque)

Head and lateral line erosion (HLLE) is a chronic dermatopathy affecting a number of fish that presents as depigmented skin along the lateral line system of the trunk and head. We present microbiological, immunological and histopathological features of this lesion in channel catfish, Ictalurus punctatus (Rafinesque), that developed after exposure to a chronic nutritional stress. Depigmention was limited to skin that was adjacent to the lateral line. The epidermis of affected fish was thin and reduced to a one-cell-thick layer over the lateral line. Melanocytes were depleted at the dermo-epidermal junction and formed aggregates in the epidermis. Innate immunity was weaker in affected fish than that previously measured in well-fed channel catfish. Because the pathology and apparent aetiology of HLLE described in various fish species are highly variable, HLLE appears to be a clinical sign, rather than a disease or syndrome. Thus, we propose that this clinical sign be referred to as lateral line depigmentation (LLD), because this description more accurately encompasses all cases of this presentation reported in fish. As nutritional requirements of channel catfish and lateral line neuroanatomy are well-known, the ability to reproducibly induce LLD in this species could provide a useful model for understanding its pathogenesis.

Uveodermatologic syndrome in an Akita

An 8-year-old, spayed, female Japanese Akita was presented for acute blindness, cloudy eyes, and squinting. A presumptive diagnosis of uveodermatologic syndrome was made. Therapy with oral prednisone, topical prednisolone, and oral azathioprine was successful in eliminating most of the clinical signs and the Akita now has complete restoration of vision.

Dermal melanocytosis in Japanese monkeys (Macaca fuscata)

The skin of Japanese monkeys (Macaca fuscata) shows diffuse discolorations resembling human dermal melanocytosis. Very few laboratory animals have melanocytes in the dermis. The purpose of this study was to clarify the dermatologic characteristics of Japanese monkeys in terms of gross appearance, skin color, and histopathologic findings. A colorimeter was used to record the skin colors of pigmented and nonpigmented sites. Tissue specimens obtained from both types of sites were examined histopathologically. All animals examined had pigmented sites on their bodies, and the discolorations extended over 25% to 33% of the body surface. The colorimeter could detect differences in skin color due to dermal melanocytosis. All parameters of the colorimetric systems used (Yxy, L*a*b*, and L*C*h* systems) demonstrated significant differences between pigmented and nonpigmented sites. In pigmented sites, the epidermis lacked melanocytes, but the dermis had numerous melanocytes with abundant melanin. Activated melanocytes with well-developed dendrites were distributed throughout the upper part of the dermal layer. Melanocytes were not arranged in clusters, and elastic and collagen fibers in the dermis showed no histological abnormalities. Nonpigmented sites lacked melanin granules in both the epidermis and dermis. This study revealed that gross dermal melanocytosis correlated well with colorimetric results and histopathologic findings. These findings suggest that the pigmentation of Japanese monkeys is equivalent to dermal melanocytosis in humans, to the end that Japanese monkeys may be a useful animal model for investigating dermal melanogenesis.

Iatrogenic Hyperadrenocorticism in 12 Cats

Iatrogenic hyperadrenocorticism is an extremely rare condition in cats. Twelve cats with a medical history of progressive skin lesions and long-term treatment with corticosteroids were retrospectively studied. Noncutaneous signs in the cats were variable and included anorexia, lethargy, polydipsia, polyuria, and atrophy of the thigh muscles. Laboratory abnormalities included leukocytosis, elevated alanine aminotransferase levels, and hyperglycemia. Transient diabetes mellitus was a secondary complication in four cats, and transient hypothyroidism was suspected in four cats. The mean time for regression of signs was 4.9 months after corticosteroid withdrawal.

Unilateral uveitis in a dog with uveodermatologic syndrome

CASE DESCRIPTION

A 7-year-old Siberian Husky-type dog with heterochromia irides was evaluated because of signs of pain associated with the right eye.

CLINICAL FINDINGS

Unilateral panuveitis, iris bombé, and secondary glaucoma were detected in the right eye. Tear production was low bilaterally. Facial and truncal poliosis and vitiligo were also evident; skin biopsy specimens were obtained from the nasal planum. Uveodermatologic syndrome was diagnosed on the basis of histopathologic findings of a lichenoid interface dermatitis and pigmentary incontinence within the dermis. Immunohistochemical analysis was performed on skin samples retrospectively, and findings were inconclusive.

TREATMENT AND OUTCOME

Treatment involved topical (ocular) and oral administration of corticosteroids, oral administration of azathioprine, and topical (ocular) administration of a carbonic anhydrase inhibitor and a lacrimostimulant. The secondary glaucoma was refractory to treatment, and the right eye was enucleated. Uveodermatologic syndrome was confirmed via histologic examination of ocular tissues. The left eye remained free of inflammation 16 months after the initial diagnosis. The periocular skin and skin of the nose partially regained pigment, but the hair did not.

CLINICAL RELEVANCE

Some breeds in which uveodermatologic syndrome has been reported (eg, Siberian Huskies, Old English Sheepdogs, Australian Shepherds, and Shetland Sheepdogs) often have heterochromia irides. This case highlights the fact that dogs with asymmetric uveal pigmentation may have unilateral ocular changes; therefore, uveodermatologic syndrome should not be excluded as a differential diagnosis on the basis of unilateral clinical signs.

Pigmentation development, defects, and patterning in summer flounder (Paralichthys dentatus)

Flounders offer unique opportunities to study the cytological basis of vertebrate pigmentation. Individual skin pigment cells are clearly visible at hatching, and flounder ontogeny includes a dramatic shift in overall pigmentation (from symmetrical to asymmetrical) during metamorphosis. Moreover, several types of malpigmentation occur in hatchery populations; although much effort has gone into reducing the frequency of such defects, their etiology remains poorly understood, and they have rarely been described at the cellular level. In this paper, we use light and fluorescence microscopy to describe the cytological basis of normal developmental changes and of common types of malpigmentation. We then discuss the implications of these observations for underlying patterning mechanisms.

Congenital neuropathy and dilution of feather melanin in nestlings of urban-breeding northern goshawks (Accipiter gentilis)

A pair of northern goshawks (Accipiter gentilis) breeding in a public park in the city center of Hamburg, Germany, raised 12 healthy and five aberrant offspring between 1996 and 2000. Aberrant nestlings (three males and two females) had pale silver-blue plumage and displayed severe locomotor disorders. Histopathologically, the defects were characterized by adendritic feather melanocytes and mild degeneration of the cerebellar white matter. Epidemiologic results were suggestive of a hereditary autosomal recessive defect, which may have originated from close inbreeding during the foundation of Hamburg's urban population of northern goshawks.

Uveodermatologic syndrome in a Brazilian Fila dog

A 5-year-old Brazilian Fila dog was presented with a history of vision loss, alopecia, and generalized depigmentation of the skin and hair. Clinical examination confirmed generalized depigmentation and pyodermitis. On ophthalmic examination there was depigmentation at the eyelid mucocutaneous junction, associated with anterior uveitis, and bilateral posterior synechia at 360 degrees. Both the complete blood count and skin scraping were normal. Skin biopsy showed histiocytary lichenoid interface dermatitis with an absence of pigment within the queratinocytes, and a moderate lymphomononuclear infiltrate and predominance of histiocytes in the papilar derma suggestive of uveodermatologic syndrome. Clinical management consisted of oral and topical administration of prednisone, associated with 1% indometacine eye drops. Methylprednisone was also used twice via the subconjunctival route, at an interval of 15 days. To prevent the development of secondary glaucoma due to posterior synechiae, dorzolamide and timolol eye drops were indicated. Both dermatologic and ophthalmic signs showed good improvement, vision was preserved, and some repigmentation of the skin and hair occurred.

Abnormal ocular pigment deposition and glaucoma in the dog

The combined occurrence of ocular pigment deposition and glaucoma has been described in Cairn Terriers. Recently, this condition was also observed in two other breeds: the Boxer (two cases) and the Labrador Retriever (one case). Six dogs were referred to the Ophthalmology section of the Department of Clinical Sciences of Companion Animals and to a private referral clinic because of glaucoma or blindness in one or both eyes. In five cases ophthalmic examination showed pigment depositions in the sclera around the entire circumference of the perilimbal zone. Eight enucleated eyes (four eyes of two Cairn Terriers, three eyes of two Boxers and one eye of a Labrador Retriever) were examined microscopically. All eyes showed the same findings: an extensive infiltration of large melanin-containing cells with an eccentric nucleus, located in the iris, ciliary body, retina, choroids and sclera. Transmission electron microscopy of two of the examined eyes revealed that the morphology of most of these cells was consistent with melanophages. While reports in the veterinary literature concerning this condition are limited the cells concerned have been described to be melanocytes. Further research is needed to conclusively identify the cell type. As described in the present report, the histologic and transmission electron microscopic findings suggest a different etiology of the ocular pigment deposition and glaucoma compared with the pigment dispersal syndrome in humans.

Epitheliotropic lymphoma (mycosis fungoides) presenting as blepharoconjunctivitis in an Irish setter

An 11-year-old neutered female Irish setter was presented with a six-week history of blepharoconjunctivitis affecting the right eye. A conjunctival biopsy was taken and histopathological examination revealed a heavy cellular infiltrate involving the epithelial and subepithelial tissues. Immunohistochemical staining showed the intraepithelial cell population to uniformly have the phenotype CD3 (T-cell specific marker). A diagnosis of epitheliotropic lymphoma (mycosis fungoides) was made. The use of a synthetic retinoid and topical prednisolone in the management of the case is discussed.

[The etiology and diagnosis of "black spot disease" of fish]

Some traditional points of view on the black spot disease in fishes caused by the metacercariae of the trematode Posthodiplostomum cuticola are revised. The black spot disease should be considered as one of several symptoms appeared in freshwater and sea fishes in cases of infection with certain parasite species. Up to present days, more than 30 parasite species causing similar symptoms are recognized. And among them 8 such species have been recorded in fishes of the Volga-Caspian region.

Treatment of localized Mycobacterium avium complex infection with clofazimine and doxycycline in a cat

Mycobacterium avium complex infection resulted in a granuloma that developed at the base of the left ear in a cat. The lesion caused vestibular dysfunction and facial palsy on the left side and protruded into the oral cavity on that side. The cat was treated successfully, with resolution of the lesion and elimination of the organism, by use of combined administration of clofazimine and doxycycline. Adverse effects of the clofazimine treatment included temporary reddish-orange discoloration of the cat's skin and mucous membranes.

Protoporphyric disorder in livers of broiler chickens

Two cases of protoporphyrin (PP) disorder detected in a 60- and 65-day old female chicken were described. The gross lesions were restricted to the livers which were enlarged and dark green to black in color. Histologically, dark brown granules were found in hepatocytes, Kupffer cells, macrophages, sinusoids, bile canaliculi, and bile ducts. These granules, as seen in smears and sections of livers, were red under a fluorescence microscope and exhibited bright birefringence with a centrally located dark Maltese-cross by polarized light. Ultrastructurally, these granules consisted of aggregates of needle-like crystals in a radial arrangement. Fluorometrically, extracted level of PP in the affected liver was determined to be 390.6 micrograms per gram of wet tissue. Spectrofluorometric scans of liver extract and PP standard were almost identical.

Effects of mutations at the W locus (c-kit) on inner ear pigmentation and function in the mouse

The W locus encodes a tyrosine kinase receptor, c-kit, which affects survival of melanoblasts from the neural crest. The primary cochlear defect in Viable Dominant Spotting (Wv/Wv) mutants is a lack of melanocytes within the stria vascularis (SV) associated with an endocochlear potential (EP) close to zero and hearing impairment. In this study, we compare inner ear pigmentation with cochlear potentials in three other W alleles (Wx, Wsh, and W41) and reveal an unequivocal correlation between presence of strial melanocytes and presence of an EP. Asymmetry was common, and 8.3% of Wsh/Wx, 25% of Wsh/Wsh, 60% of W41/Wx, and 69.2% of W41/W41 ears had a pigmented stria and an EP, while the remainder had no strial melanocytes and no EP. In those mutants that partially escaped the effects of the mutation, strial melanocytes rarely extended the entire length of the stria, but were confined to the middle and/or basal turns of the cochlea. The extent of strial pigmentation was unrelated to the EP value, which was measured from the basal turn only. Compound action potential (CAP) responses recorded from ears with an EP were variable and they showed greatly raised thresholds or were absent in all ears where the EP was close to zero. In controls, melanocytes in the vestibular part of the ear were found in the utricle, crus commune, and ampullae, whereas in many mutants only one or two of these regions were pigmented. There was a broad correlation between pigmentation of the stria and pigmentation of the vestibular region but this was not absolute. All W41/Wx, Wsh/Wsh, and W41/W41 mutants had some pigment on the pinna but, in contrast to controls where melanocytes were found in the epidermis and dermis of the pinna, pigment cells were reduced in number and generally restricted to the dermis. Injection of normal neural crest cells into 9.5-day-old mutant embryos increased the extent of skin pigmentation on the head and coat of adult chimeras and was associated with a small increase in the proportion of pigmented strias.

[The uveodermatologic syndrome in dogs]

A review of the literature pertaining to the uveodermatological syndrome of dogs is presented. This syndrome is marked by depigmentation of the periocular region, lips and nose in association with severe uveitis. Early diagnosis and therapy can prevent serious vision loss. Symptoms and therapy of the cases described in the literature as well as cases seen at the Veterinary Medical Teaching Hospital in Davis/California are discussed.

The use of high-performance liquid chromatography for studying pigmentation

The use of HPLC has established that chickens possess unexpected metabolic abilities to acylate, deacylate, reduce, and oxidize carotenoids. The use of HPLC permits more consistent and more economic pigmentation of carcasses and of egg yolks. Hopefully, the use of HPLC will raise pigmentation from an art to a science. Apparently, HPLC will be an essential tool in terms of future efforts to understand and master the process of poultry pigmentation.

[Cu deficiency in growing dogs]

It was the aim of the investigation to evaluate the influence of marginal (60-30 micrograms/kg BW/d) or adequate (680-360 micrograms/kg BW/d) Cu-intake on the development of growing beagles (n = 10) and the incidence of skeletal diseases. Low Cu-intake (6 dogs) reduced Cu-concentrations in plasma (1.4 vs. 9.7 mumol/l), hair (3.3-4.5 vs. 12.6-14.5 mg/kg DM), liver (19 vs. 246 mg/kg fat free DM), bile (0.28 vs. 7.04 mg/l), and other samples significantly. Hemoglobin and packed cell volume decreased after 4 months of depletion (normochromic anemia). First clinical signs of Cu-deficiency were depigmentation and greying of hair, followed by hyperextensions in the distal forelegs. After necropsy deformations of the long bones were seen more frequently in the depleted animals, without distinct alterations of the microstructure or chemical composition of bones or tendons.

Pachyonychia congenita-like disorder in cotton-top tamarins (Saguinus oedipus oedipus)

A spontaneous genodermatosis in 13 cotton-top tamarins is described as a retrospective study. The disease appeared as alopecia, pigmentary disturbances, and claw dystrophy similar but not identical to human Pachyonychia congenita. The disease in the tamarins seems to be inherited as an autosomal recessive trait, becoming clinically apparent around adolescence. In certain families the neonatal mortality rate was also above average, reaching 100%.

Altered metabolism of carotenoids during pale-bird syndrome in chickens infected with Eimeria acervulina

The progression of changes in carotenoid metabolism during pale-bird syndrome caused by a coccidial infection was investigated. Male broiler chickens 15 days of age on a yellow corn and soybean meal-based diet were infected with Eimeria acervulina oocysts and their serum, liver, and toe webs were sampled at 0, 4, 6, and 10 days postinfection for HPLC analysis of carotenoids. At 4 days postinfection a drastic reduction (71%) in serum lutein, the main body carotenoid, and smaller reductions in liver (58%) and toe webs (38%) occurred. Derivative forms of lutein, mainly esters, continued to be lost from tissues for 10 days postinfection. These carotenoids were apparently lost via the intestinal tract because birds placed on a white corn and soybean meal-based diet at time of infection had lutein in their jejunal contents even at 7 days postinfection. The loss of carotenoids from the body was accompanied by a decreasing ability to absorb canthaxanthin, a red carotenoid, from the intestinal contents. The absorption of canthaxanthin measured at 0, 3, 4, 5, 6, and 7 days reached its low point of 1% of preinfection ability on Day 5 before a slow recovery commenced. Thus, the pale-bird syndrome caused by E. acervulina appeared to be the result of a loss of previously absorbed carotenoids coupled with drastic malabsorption of dietary carotenoids.

Efficacy and toxicity of VAC chemotherapy (vincristine, doxorubicin, and cyclophosphamide) in dogs with hemangiosarcoma

Fifteen dogs with hemangiosarcoma were treated with a combination of vincristine, doxorubicin, and cyclophosphamide after incisional or excisional biopsy. The median survival for all fifteen dogs was 172 days (mean survival = 316 days). The median survival for those dogs with splenic hemangiosarcoma was 145 days (mean survival = 271 days) as compared with previously published median survival times in dogs with splenic hemangiosarcoma treated with surgery alone of 19 to 65 days. Toxicities included neutropenia (11/15), severe gastroenteritis (4/15), cardiotoxicity (3/15), and sepsis (2/15). The authors conclude that vincristine, doxorubicin, and cyclophosphamide chemotherapy may be an efficacious treatment modality in dogs with hemangiosarcoma and is associated with acceptable toxicity.

Hormonal abnormalities in Pomeranians with normal coat and in Pomeranians with growth hormone-responsive dermatosis

Clinical status, skin biopsy specimens, and endocrine function were evaluated in normal-coated Pomeranians (n = 12) and Pomeranians affected with growth hormone (GH)-responsive dermatosis (n = 7), then were compared with values in mixed-breed dog controls (n = 19). All Pomeranians were clinically normal; however, the Pomeranians with GH-responsive dermatosis had bilateral alopecia and hyperpigmentation of the trunk, caudal portion of the thighs, and ventral neck region. Skin biopsy specimens from the affected Pomeranians had decreased-to-normal epidermal thickness and follicular atrophy, compared with normal-coated Pomeranians. Numerous elastin fibers were observed in the skin biopsy specimens of unaffected and affected Pomeranians. Both groups of Pomeranians had normal results of thyrotropin-releasing hormone (TRH) and thyrotropin (TSH) response, adrenocorticotropin (ACTH) stimulation, and dexamethasone suppression testing. There was no significant increase in serum GH concentration in either group of Pomeranians after xylazine or human GH-releasing factor (GHRF) administration, whereas control dogs had significant (P less than or equal to 0.05) increase in serum GH concentration after administration of either agent. Baseline plasma ACTH concentration in unaffected and affected Pomeranians was increased above the normal range (40 to 90 pg/ml). Post-ACTH administration serum progesterone, 17-hydroxyprogesterone, and androgen (dehydroepiandrosterone sulfate or androstenedione) concentrations were consistently high in unaffected and affected Pomeranians, compared with values in control dogs.(ABSTRACT TRUNCATED AT 250 WORDS)

Lipopigments in veterinary pathology: pathogenesis and terminology

The lipopigments are a heterogenous group of pigments whose pathogenesis and terminology is confused. Whereas there is epidemiological and observational evidence that ceroid is derived from degeneration and peroxidation of unsaturated lipid, the assumption that all so-called lipopigments are similarly formed, is questioned. In particular, recent studies have distanced the pathogenesis of the pigment found in the ceroid-lipofuscinoses from that perceived for ceroid. The importance of protein rather than lipid in the pathogenesis of the pigment of ceroid-lipofuscinosis and of age pigment from the equine thyroid is noted. In the former the essential feature is storage of the DCCD binding protein subunit c of mitochondrial ATP synthase. There is a need for more analytical studies on isolated pigments which are generally more soluble than anticipated by the literature. It is proposed that the term ceroid be limited to a family of pathological pigments where lipid degeneration and peroxidation is implied from observational and/or epidemiological factors. The term age pigment is unequivocal and preferred for age related pigment not obviously complicated by other factors. The terms lipofuscin and lipopigment retain a usefulness as generic terms, particularly where the nature of the pigment is uncertain. The term ceroid-lipofuscinosis for the inherited storage diseases of children and animals is misleading. The term "proteolipid proteinosis" has been suggested to define this group of diseases but this is perhaps premature until their full pathogenesis is known.

Effect of eumelanic phenotypes on the expression of amelanosis in the Smyth chicken

The Smyth line is characterized by an autoimmune loss of melanin in the feather and eye in association with a hypermelanizing melanocyte, which presumably triggers immune system intervention. Inheritance appears to be multigenic. The present study was designed to determine if eumelanin-enhancing modifiers influence the incidence and severity of the line-associated amelanosis. Smyth chicks with dark brown (eb) down had a higher incidence of amelanosis (P less than .01) than did their hatchmates with light brown down. Furthermore, parents with dark down at hatch produced a higher incidence of amelanotic progeny than parents with light down. Reciprocal crosses of the Smyth line to a highly eumelanized (eb/eb) Recessive Black (RB) line produced F1 amelanosis. However, sires from the Smyth line produced significantly more amelanotics than did RB males (P less than .01). The influence of dark down on amelanotic development was also apparent in the Smyth-RBF1. The use of amelanotic F1 parents produced a significantly higher incidence of affected F2 offspring than did the use of unaffected parents. A backcross to the Smyth line produced an incidence of 67.6% amelanosis, whereas only one chick (2.04%) developed amelanosis from an F1 x RB mating. The finding that dark-downed Smyth chicks exhibit, and subsequently produce, a significantly higher incidence of amelanosis supports ultrastructural observations that associate the Smyth line amelanosis with a hyperactive melanocyte. The unusually high expression of amelanosis (22.7%) in the Smyth-RB F1 suggests that the two lines share one or more common eumelanogenic genetic factors.

Depletion of oxycarotenoid pigments in chickens and the failure of aflatoxin to alter it

Aflatoxin, a demonstrated cause of pale bird syndrome in chickens, was investigated for its effects on the depigmentation of chickens placed on a diet low in carotenoids. Chickens were pigmented by feeding for 3 wk a white corn-soy diet supplemented with 50 micrograms free lutein and 0 or 4 micrograms aflatoxin/g diet. Then birds were switched to the same diets unsupplemented with lutein. At 0, 1, 2, 3, 6, and 9 days after switching, jejunal contents and mucosa, serum, liver, and toe web of 4 groups of 10 birds were removed for analysis of their carotenoids by high performance liquid chromatography. In control birds the order of decrease in total lutein was jejunal contents greater than jejunal mucosa greater than serum greater than liver greater than toe web. Aflatoxin did not alter the depletion process, except for minor retardation of lutein depletion in the mucosa and liver. Pharmacokinetic analysis of the data indicated that lutein depletion in the integument was accomplished through three sequential reactions (lutein diester----lutein monoester----lutein----serum lutein) and that aflatoxin had no effect on the reactions. These results imply that aflatoxin induces pale bird syndrome by interfering with the accumulation of pigment by chickens rather than by enhancing the depletion of pigment.

Aflatoxin-impaired ability to accumulate oxycarotenoid pigments during restoration in young chickens

The mechanism by which aflatoxin causes paling in chickens was investigated by measuring its effect on the restoration of pigments in 3-wk-old birds made pale by feeding a white corn-soy diet. Pigment restoration was accomplished by feeding the same diet supplemented with lutein (70 micrograms/g of diet), which is the major oxycarotenoid pigment in chicken diets and tissues. The oxycarotenoids (free, monoester, and diester forms of lutein) in the toe web, liver, serum, and jejunal mucosa of control and aflatoxin-fed (2 micrograms/g of diet) birds were measured by HPLC at 0, 1, 2, 3, 6, and 9 days of repletion. Aflatoxin caused a significant (P less than .05) depression of all forms of lutein in the toe web. In the liver, aflatoxin decreased lutein significantly (P less than .05) but increased lutein monoester and lutein diester. Lutein accumulation in serum and mucosa were inhibited significantly (P less than .05) starting on Days 2 and 3, respectively. These data imply that the normal accumulation of lutein from the diet proceeded into and through the mucosa to the serum to depot sites in the liver and integument, where lutein was acylated to its monoester, which was acylated to its diester. Further, aflatoxin inhibited, apparently independently, the accumulation of lutein by the mucosa, serum, liver, and integument. Pharmacokinetic analysis of the data indicated that both acylation steps in the integument were sensitive to aflatoxin, but the passage of lutein from serum into the integument was not affected.

Langerhans' cells in hair follicles of the depigmenting C57Bl/Ler-vit.vit mouse. A model for human vitiligo

The C57Bl/Ler-vit.vit mouse grows a black pelage after birth. During successive hair molts, the fur loses its pigmentation. By 6 months of age, most of the fur of the animal is white. The epidermis of the ears and tail also loses its pigmentation. Histologic studies confirm that in the epidermis and hair follicles there is an absence of pigment cells identifiable by various histochemical or electron microscopic techniques. This mouse may be an excellent model in which to study the role of Langerhans' cells and the immune response in the pathogenesis of vitiligo, a study not easily done in humans. From results of prior studies, we postulated that if Langerhans' cells were involved in the destruction of melanocytes, they would be abnormal (either more or less numerous) in number during the active phase of depigmentation and normal in number after depigmentation was complete. To determine whether the Langerhans cell (Ia+/adenosine triphosphatase dendritic epidermal cell) might be involved in destruction of pigment cells, we quantified the number of Ia+ and adenosine triphosphatase dendritic cells in the hair follicles in skin from the ear, abdomen, back, and tail from male C57Bl/Ler-vit.vit mice while the fur and skin were depigmenting and after depigmentation was almost completed. We found that Langerhans' cells were normal in number during depigmentation and were most numerous after depigmentation. Previous studies indicate that Langerhans' cells in these mice are functionally defective and respond poorly to some contact allergens. From these morphologic and functional data, we conclude that Langerhans' cells probably are uninvolved in causing depigmentation in these mice. We also observed that the epithelium of hair follicles has a significantly higher (up to 1600/mm2) population density of Langerhans' cells than interfollicular skin.

Diseases of the lips and oral cavity of domestic animals

Oral and lip lesions in domestic animals, as in man, may be due to a vast number of diseases. While some of these diseases are unique to each species, the majority of them are similar to human afflictions. These represent an untapped resource in comparative medicine, and research in this area can only benefit both man and the domestic animals he is dependent upon.

Effect of corticosterone on the incidence of amelanosis in Smyth delayed amelanotic line chickens

The Smyth Delayed Amelanotic (SDA) line chicken exhibits a postnatal loss of pigment in feathers and choroid presumably due to an autoimmune reaction triggered by a basic pigment cell defect. The present study was designed to determine if the incidence and severity of amelanosis would be affected by administration of corticosterone (CS) in feed. The SDA line chickens were given 0, 20, 30, 40, and 50 ppm CS from 4 to 12 weeks of age. Body weight and incidence of amelanosis were determined weekly and immune response to sheep red blood cells was determined at the end of the trials. Body weight and immune response levels were significantly lower in treated groups than in controls (P less than .001), but no significant differences were found between treated groups on measures of amelanosis or immune response. Incidence of amelanosis in controls (60%) was significantly greater than in treated groups: 20 ppm, 14.2%; 30 ppm, 17.9%; 40 ppm, 12.9%; and 50 ppm, 16.7%. Six weeks posttreatment, treated groups were no longer significantly different from controls in terms of the incidence of amelanosis. It is proposed that the reduction in amelanosis during CS treatment is attributable to suppression of antibody response to the pigment cell antigen by the CS.

Faded shaker, a lethal pigment and neurological mutation in the chicken

Faded shaker (fs) is a lethal condition in chickens resulting in a congenital tremor and a dilution of down and feather melanin. It is inherited as an autosomal recessive gene with the homozygote showing incomplete penetrance, the apparent result of a single dominant gene masking the effects of the fs/fs genotype. Mortality of the mutants occurred between 18 days of incubation and three months of age; most died before one week of age with half of the mutants dying before hatching. No specific cause of death was observed. The tremor had a frequency of 6 to 10 vibrations per second, was more pronounced in the posterior end of the bird and was constant over time within an individual. Weight of the faded shaker cerebellum was reduced by 7.6%, presumably due to an observed deficiency of myelin. The down and feather color of faded shakers ranged from almost normal to near white, but was constant over several feather generations within an individual. Faded shaker melanosomes were both deficient in number and incompletely melanized. Melanocyte dendrition and melanosome distribution were both normal. Skin transplants showed that the dilution was a result of a defect located in the fs/fs skin. Pigmentation of the retinal pigment epithelium also was abnormal.

Delayed-amelanotic (DAM or Smyth) chicken: melanocyte dysfunction in vivo and in vitro

Chickens of the autoimmune delayed-amelanotic (DAM or Smyth) line develop postnatal feather amelanosis and severe visual defects, both of which are presumed to be due to a dysfunction of melanocytes and a subsequent autoimmune response that eliminates pigment cells. In this report we elucidate further the melanocytic defect. We present a morphologic analysis of the mildly affected erratic (eDAM) group of Smyth chicken whose partial depigmentation and lack of visual impairment resemble human vitiligo more so than do the complete amelanosis and blindness in the classical Smyth line. Histologically, the sequential events leading to amelanosis in the young Smyth chicken occur simultaneously in the feathers of adult eDAM Smyth chickens, and the infiltration of the feather pulp with mononuclear leukocytes correlates with the extent of local pigmentary abnormality. Cytochemical localizations of dopa-oxidase and acid-phosphatase activities in eDAM feather melanocytes suggest that melanogenesis and autophagocytosis of melanosomes occur in tandem and that the rates of both are higher in these cells than in melanocytes of normally pigmented control chickens. Assays for tyrosinase activity in feather follicles indicate a hypermelanization in eDAM feathers and in the pigmented feathers of young Smyth chicks prior to the onset of depigmentation. Finally, we report on the establishment of pure, proliferative cultures of neural crest-derived melanocytes from control and Smyth chicken embryos. The degenerative events in Smyth chicken melanocyte cultures mimic in part those of the cells in vivo and are therefore indicative of a genetic defect that is independent of the immune system.

Paralysis and lipofuscin-like pigmentation of farm stock caused by the plant, Trachyandra laxa var. laxa

A paralytic condition of farm stock in South West Africa, characterized by prominent neuronal and some mild extraneuronal pigmentation, is described. The distribution of the pigment, which was mainly located in the larger neurones of the brain and spinal cord, is given. Experimental evidence, obtained by feeding the plant, is presented that the condition is caused by Trachyandra laxa var. laxa. The histochemical features of the pigment proved to be compatible with a lipofuscin.

Uveitis associated with poliosis and vitiligo in six dogs

Idiopathic panuveitis with retinal detachment was associated with facial poliosis, vitiligo, and alopecia in 6 dogs; 4 were adult males. Dermatohistologic examination of affected facial sites from all dogs revealed a lichenoid dermatitis and unusual histiocytic cells. Intensive topical and systemic corticosteroid and topical mydriatic/cycloplegic therapy was successful in controlling uveitis in all dogs for variable periods. Three dogs, monitored for 12, 30, and 46 months, retained useful vision despite infrequent recurrence of uveitis. One dog was lost for subsequent examination. Two dogs were euthanatized and necropsied. Ocular histologic examination of these dogs revealed extensive granulomatous iridocyclitis and choroiditis, with retinal detachment and lenticular degeneration.

Association of megacolon with a new dominant spotting gene (Dom) in the mouse

A new semidominant mutation in the mouse is described. In heterozygotes it produces white spotting and a deficiency of myenteric ganglion cells in the colon and, in homozygotes it is lethal prior to 13 days of gestation. The mutation, called dominant megacolon, symbol Dom, is located on chromosome (chr) 15, 20.6 +/- 1.6 units proximal to Ca. Hairy ears, Eh, a semidominant gene also on chr 15 is shown to have a suppressing effect on crossing over in this section of chr 15.

Effect of selection for delayed amelanosis on immune response in chickens. 1. Antibody production

Studies were conducted to compare the antibody production of the Delayed Amelanotic (DAM) line of chickens with that of the line from which it originated, the Brown line (BR), and a distantly related environmental control, the Light Brown Leghorn (LBL). Total agglutinating antibody titers following immunization with sheep red blood cells (SRBC) or Brucella abortus (BA), were determined at 4, 6, 8, 10, 12, 16, and 20 weeks. The SRBC titers of DAM line birds were significantly higher than those of LBL birds but not BR birds at young ages (4 to 8 weeks) and at 20 weeks. The BA titers of DAM and BR lines were significantly higher than those of the LBL line at 4 and 6 weeks. We conclude that the DAM line exhibits hyperreactivity in B-cell function, which may be related to the line-associated pigmentation destruction. These studies also confirm that age is an important factor in making comparisons of antibody production between different genetic stocks.