Histopathology and Immunohistochemistry of Canine Distemper Virus-induced Footpad Hyperkeratosis (Hard Pad Disease) in Dogs with Natural Canine Distemper

Hard pad disease represents an uncommon manifestation of canine distemper virus (CDV) infection with a still uncertain pathogenesis. To study the pathogenesis of this uncommon, virally induced cutaneous lesion, the footpads of 19 dogs with naturally occurring distemper were investigated for histologic changes and distribution pattern of CDV antigen. All dogs displayed clinical signs of distemper, which had lasted from 10 to 75 days. Overt digital hyperkeratosis was observed in 12 animals (group A), whereas the footpads of the remaining seven dogs appeared normal macroscopically (group B). Orthokeratotic hyperkeratosis (12/12; 100%), irregular acanthosis (11/12; 92%), thickened rete ridges (10/12; 83%), and mild mononuclear perivascular (10/12; 83%) and periadnexal (7/12; 58%) dermatitis were the most common findings in dogs with hard pad disease. Surprisingly, orthokeratotic hyperkeratosis (5/7; 71%), irregular acanthosis (5/7; 71%), and thickened rete ridges (4/7; 57%) were also seen in the dogs without clinical evidence of digital hyperkeratosis. CDV-specific inclusion bodies and ballooning degeneration were not observed in the footpad epidermis of the 19 dogs. Immunohistochemistry revealed that CDV antigen was most frequently found in the stratum spinosum and granulosum and in the epithelial cells of the eccrine sweat glands and only rarely in the basal layer. Fibroblasts, pericytes, endothelial cells, and hair follicles were also positive in some animals. Despite the obvious difference regarding the macroscopic picture, the microscopic changes were less prominent between the animal groups. The selective infection of keratinocytes in the stratum spinosum might be the key event for the development of hard pad disease in the dog.

Characterization of a novel papillomavirus species (ZcPV1) from two California sea lions (Zalophus californianus)

A seven-year old California sea lion (Zalophus californianus) presented with focally extensive, bilaterally symmetric, proliferative axillary skin lesions and preputial lesions. A second California sea lion in the same population presented with similar proliferative lesions on the underside of the tail. Histopathology revealed epidermal hyperplasia with severe hyperkeratosis, with proliferating keratinocytes forming broad, branching pegs that extended into the dermis. Pan-papillomaviral consensus PCR was used to obtain initial E1 sequence template and the complete genome was determined using a combination of rolling circle amplification and specific-primer PCR. Analysis revealed a novel papillomavirus, Zalophus californianus papillomavirus 1 (ZcPV1), with seven open reading frames encoding five early proteins (E6, E7, E1, E2 and E4) and two late proteins (L1 and L2). Phylogenetic analysis revealed that (ZcPV1) is most closely related to Equine papillomavirus 1 (EcPV1) in the genus Zetapapillomavirus, and Canine papillomaviruses 3 and 4 (CPV3, CPV4) in the genus Chipapillomavirus. The lesions regressed without intervention over a period of several months.

Multiple keratomas in an equine foot

A 19-year-old, Arabian gelding was presented for left hindlimb lameness and deviation of the hoof wall. Radiographs revealed a semicircular, radiolucent area in the lateral edge of the distal phalanx. Three distinct keratomas were successfully removed following hoof wall resection.

[Skin lesions in small mammals parasitized by Psorergates apodemi and P. dissimilis (Gheyletoidea: Psorergatidae)]

Histopathology in the sites of localization and parasiting of the mites Psorergates apodemi Fain et al., 1966 and P. dissimilis Fain et al., 1966 on the Ural field mouse Apodemus uralensis (Pallas) and the bank vole Clethrionomys glareolus (Schreber) is described. The mites affected all epidermis cell layers down to the cambium layer and caused hyperkeratosis.

Complete and partial hoof wall resection for keratoma removal: post operative complications and final outcome in 26 horses (1994-2004)

REASONS FOR PERFORMING STUDY

There are no data on the frequency of post operative complications following keratoma removal, such as recurrence, hoof wall instability and excessive granulation tissue formation, or their relation to the method of surgical removal.

OBJECTIVE

To identify important factors in the outcome for horses undergoing surgical removal of a keratoma and compare the post operative complications encountered following keratoma removal by complete hoof wall resection (CR) and partial hoof wall resection (PR).

HYPOTHESIS

Horses undergoing PR would have fewer post operative complications and would return to work more quickly than those undergoing CR.

METHODS

A retrospective review of medical records from one equine hospital identified 26 horses that underwent removal of a keratoma by CR or PR. Clinical, radiological and surgical findings and outcome were analysed.

RESULTS

Common clinical signs included lameness and the presence of a subsolar abscess. Fourteen horses underwent CR and 12 PR. The complication rate following CR (71%) was significantly lower than that following PR (25%) (P<0.01). Complications encountered included excess granulation tissue formation, hoof crack formation and keratoma recurrence at the surgical site. The time taken to return to full work post operatively was significantly shorter in horses undergoing PR compared to CR (P<0.01). All horses, except one, returned to their previous exercise level.

CONCLUSIONS

PR resulted in fewer post operative complications and a more rapid return to athletic activity than CR.

POTENTIAL RELEVANCE

Although the overall complication rate for CR was higher than for PR, the overall prognosis for return to soundness and the previous performance level is very good.

Immunohistochemical demonstration of connexin-related epithelization defects in a lamb caused by (erythro)keratodermia variabilis

The distribution of four important connexins (Cx 26, 30, 31, 43) in the skin of a neonatal lamb with (erythro)keratodermia (EKV) was demonstrated using immunohistochemistry, including a very sensitive visualization system. The reaction staining for Cx 26, 30 and 31 was negative to weak in all skin structures, and only Cx 43 displayed weak to moderate positive reactions, although not uniformly distributed throughout the important systems (e.g. epidermis, hair follicle sheaths). Thus, the study proves for the first time that connexin defects are associated with the development of EKV in domesticated mammals, as they are in humans.

Efficacy of two iodine teat dips based on reduction of naturally occurring new intramammary infections

The efficacy of 2 teat dips, product 1 (Della Care with 5 to 8 ppm of free iodine, used as a positive control) and product 2 (New Della Care with 12 to 16 ppm of free iodine), was compared using a natural exposure trial on dairy cattle. The trial was based on National Mastitis Council guidelines and performed over 9 mo. Both teat dips contained 0.25% iodine. Product 2 reduced the infection rate 57.6% for major pathogens and 53.7% for minor pathogens, compared with the positive control. Product 2 gave highly significant reductions for Staphylococcus aureus, coagulase-negative staphylococci, and Corynebacterium bovis. Teat skin, teat ends, and teat hyperkeratosis were evaluated during trial. No significant difference in teat condition was observed between these 2 products.

[Retrospective evaluation of surgical versus conservative treatment of keratomas in 41 lame horses (1995-2001)]

A keratoma is a rather uncommon disorder of the equine hoof that can lead to lameness. Few quantitative data exist about the prognosis of different treatment regimens. The outcome of 41 cases that were presented to the Department of Equine Sciences in the period 1995-2001 and that were treated according to different regimens was retrospectively evaluated. All horses showed lameness that could be attributed to the keratoma: 23 (56%) were treated surgically using a standardized procedure, while the other 18 (44%) were treated conservatively. Results were based upon 35 horses; 6 were lost to follow-up. Range of recovery time for the surgically treated patients, was 2-12 months and for the conservatively treated group 2 weeks to 6 months. Of the surgically treated patients 83% (n =23) returned to the same or higher performance level as before the onset of the lameness, as opposed to 42% (n = 12) of the conservatively treated horses (p<0.05). The average hospitalization period was significanty longer for the surgically treated patients (35 vs. 5 days, p<0.05). It is concluded that surgical excision of the keratoma is the preferred treatment for horses suffering from lameness caused by a keratoma, because the better outcome outweighs the longer hospitalization and the longer overall recovery time.

[Another indication for (erythro)keratodermia variabilis in livestock in the case of a neonatal lamb]

From skin biopsies of a neonatal lamb a congenital skin disease (erythro)keratodermia variabilis was diagnosed which especially showed besides an erythema formation a hyperkeratosis at some wound areas of the body. Despite of a sudden induced intensive therapy the lamb died. At the dissection of the carcass there were no further postmortem-findings which refer to another organic disease than the one of the skin. This case report is the second description of (erythro)keratodermia variabilis in domestic mammals, which is caused by an autosomal dominant inherited horning defect in humans.

Hoof wall surgery in the horse: approaches to and underlying disorders

Because of the hoof capsule, surgery of the equine foot is often perceived to be quite difficult. Knowledge of the specific disease entities that require surgical intervention as well as an in-depth understanding of the anatomy of the tissues beneath the hoof capsule is a definite prerequisite to successful surgical treatment. This article details the surgical approaches used to treat septic navicular bursitis, septic pedal osteitis, infection of the collateral cartilages, and keratomas. The principles used to treat these conditions can be applied to a variety of other conditions for which access through the hoof wall is required.

Suspected hypovitaminosis A in a colony of captive green anoles (Anolis carolinensis)

In a colony of 18 green anoles (Anolis carolinensis), 3 animals experienced focally thickened lips, ulcerative cheilitis, lethargy, depression, and weight loss over a 5-month period. In addition to crickets fed fresh fruit and leafy green vegetables, the diet of the green anoles consisted of a supply of mealworms that had been dusted with a commercial liquid vitamin supplement. The history, clinical findings, and histopathologic lesions were suggestive of hypovitaminosis A, which is known to cause squamous metaplasia of the mucus secreting glands and epithelial surfaces in many species.

[Case report: (erythro)keratoderma variabilis in a newborn foal]

A case of congenital (Erythro)keratoderma variabilis in a newborn foal is described. The clinical and histological findings are presented.

Immunohistochemical study of the inflammatory infiltrate associated with equine squamous cell carcinoma

The distribution of T (CD3), B (CD79) lymphocytes, immunoglobulin (IgG, IgM and IgA)-producing plasma cells, macrophages (lysozyme, Mac387) and MHC Class II antigen was analysed in the inflammatory infiltrate associated with 19 equine squamous cell carcinomas (SCCs) and six cases of precancerous lesions (actinic keratosis). The SCCs came from the penis (11 cases), conjunctiva (four), skin (two), nasal cavity (one) and oral cavity (one). Seven cases were well-differentiated and 12 moderately differentiated. Nine cases showed no invasion of peritumoral deep tissues (locally invasive), whereas the remaining 10 cases were highly invasive. An abundant inflammatory infiltrate was associated with the majority of the SCCs and with lesions of actinic keratosis. This infiltrate was composed mainly of CD3(+)T lymphocytes, CD79(+)B cells and numerous IgG(+)plasma cells; IgM- and IgA-producing plasma cells were scarce and variable, respectively. Macrophages were usually numerous. Macrophages, lymphocytes, intra-epithelial dendritic cells and fibroblasts expressed MHC Class II antigen. No significant correlation was found between the nature of the inflammatory infiltrate and the SCC histological grade or degree of invasion, suggesting that the local anti-tumour immune response failed to prevent tumour invasion or metastasis. MHC Class II was expressed by a variable number of neoplastic epithelial cells in four SCCs, all of which were only locally invasive. In addition, in areas where SCC cells expressed Class II antigen, numerous CD3(+)T lymphocytes were present and some of them were associated with degenerate tumour cells. These findings suggest that the expression of MHC Class II by neoplastic cells induces an improved local anti-tumour immune response.

Ovine cutaneous squamous cell carcinoma: immunohistochemical expression of CD3, CD4, CD8 and MHC class II antigens in the associated inflammatory infiltrate

The immunohistochemical expression of CD3, CD4, CD8 and MHC class II antigens in the cellular inflammatory infiltrate associated with early and advanced ovine squamous cell carcinomas (OSCC), as well as actinic keratosis was analyzed. The majority of the peritumoral and intratumoral lymphocytes reacted with the anti-human CD3 polyclonal antibody. The number of CD8+ T lymphocytes increased in advanced OSCC compared with that of actinic keratosis and early OSCC, whereas the number of CD4+ lymphocytes was similar in early and advanced OSCC. Tumor cells were unreactive with the anti-MHC class II antibody, but the majority of the mononuclear cellular infiltrate expressed this antigen in early and advanced tumors.

Treatment of a keratoma in a Clydesdale horse

A keratoma was diagnosed in a six-year-old Clydesdale gelding with recurrent 'pus in the foot'. The keratoma was excised through an inverted 'V' dorsal wall hoof resection up to 2 cm distal to the coronary band, the foot was bandaged and shod, and the horse treated with antibiotics and phenylbutazone. The dorsal hoof wall regrew completely and the horse gradually returned to full work.

Hyperkeratosis of the teat duct orifice in the dairy cow

Teat orifice hyperkeratosis, a commonly observed condition in dairy cows, has been considered a consequence of machine milking and the degree of hyperkeratosis may be increased by a poor milking system. A fully illustrated technique is described which uses a scoring system from 0 for a perfect orifice to 5 for an orifice significantly enlarged with extensively protruding fronds of teat duct keratin. A range of scores found in 25 commercial dairy herds is presented. The scores have been averaged for each cow and the markedly skewed distribution corrected by a square root transformation. This scoring procedure allows comparative measures of hyperkeratosis within and between herds. An 8-fold difference (0.17-1.31) in herd average score was found. Within all herds the score increased with lactational age of the animals and peaked, for any lactation, some 3-4 months post partum, declining as the animals dried off. There was no significant relationship between mean somatic cell count and degree of hyperkeratosis at the herd level. This implies that such chronic pathological changes are unlikely to be related to the level of intramammary infection. It appeared that some hyperkeratosis is an obvious and probably natural response to milking and occurs in a significant proportion of animals in all herds although often only to a slight degree. Much more hyperkeratosis may be a measure of the performance and management of the herd. The genetic influence is unknown. Higher yielding cows will score higher as they milk for longer, but generally high scores may reflect consistent and possibly considerable overmilking. Hyperkeratosis may be an indicator of the quality of management and show the level of attention being paid to the welfare of the herd.

Metabolic epidermal necrosis in two dogs with different underlying diseases

Two dogs with metabolic epidermal necrosis had hyperkeratosis of the footpads accompanied by erythematous, erosive and crusting lesions affecting the muzzle, external genitalia, perineum and periocular regions. Histopathological examination of skin biopsies revealed a superficial hydropic dermatitis with marked parakeratosis. Both dogs had high plasma activities of alkaline phosphatase and alanine aminotransferase and high concentrations of glucose, and also a marked hypoaminoacidaemia. Despite these similarities, the cutaneous eruptions were associated with different underlying diseases. One dog had a pancreatic carcinoma which had metastasised widely; the primary tumour and the metastases showed glucagon immunoreactivity on immunocytochemical staining, and the dog's plasma glucagon concentration was markedly greater than that of control dogs. The other dog had diffuse hepatic disease; its plasma glucagon concentration was similar to that of control samples and cirrhosis was identified post mortem. Metabolic epidermal necrosis in dogs is a distinct cutaneous reaction pattern which may be associated with different underlying systemic diseases; however, the pathogenesis of the skin lesions remains unclear.

Hyperkeratosis in athymic nude mice caused by a coryneform bacterium: microbiology, transmission, clinical signs, and pathology

The purpose of this study was to characterize a spontaneous disease condition causing hyperkeratosis in nude mice and to explore the etiologic role of a particular species of coryneform bacteria in this disease, colloquially known as "scaly skin disease." The study was divided into two parts. In the first phase, a series of inoculation experiments was conducted with a field isolate of the coryneform species used to study the clinical and histopathologic development of the disease syndrome. Athymic nude mice (4 to 5 weeks old) were inoculated on the skin of the back with a suspension of a pure culture of the coryneform bacterium that had been isolated from a field case. The culture was applied with a sterile cotton swab in concentrations varying from 6.1 x 10(4)/ml to 5.0 x 10(7)/ml. All inoculated mice became persistently infected throughout the 33 days of the experiment. Clinically evident hyperkeratosis in inoculated animals developed more frequently in mice housed in a microisolator cage than in a semi-rigid isolator and more frequently in mice inoculated with higher numbers of organisms. In all animals in which hyperkeratosis developed, it was first noted on day 7 after inoculation. The second series of experiments was designed to determine the success of various housing methods in excluding the infection, mechanisms of transmission, susceptibility of other stocks and strains of mice to the organism, and whether the other strains might serve as a source of the organism. Results of the study in various strains indicated that both immunocompetent and immunodeficient mice, whether glabrous or hirsute, could be infected with the organism, but only glabrous animals developed hyperkeratosis.(ABSTRACT TRUNCATED AT 250 WORDS)

Epidemiologic findings in congenital anemia, dyserythropoiesis, and dyskeratosis in polled Hereford calves

Congenital dyserythropoiesis and dyskeratosis occur within certain lines of Polled Hereford cattle. Eighty-nine of 90 alleles in 45 affected calves had a mechanism in which they could be identical by descent from an identified common ancestor. The line allele may have been a recurrence of the mutation, or the mutation may have occurred earlier in the breed's history and been distributed throughout the breed by the extensive use of several ancestors. No evidence of disease has been identified in sire and dams of affected calves, suggesting that the allele is not acting in a dominant or incompletely dominant manner. Even distribution of cases between sexes suggests that the disease is not sex linked or sex influenced. A higher degree of inbreeding in the affected calves and temporal and spatial features that separated individual cases also suggest a genetic cause. Segregation ratios were not significantly different from those of the hypothesized simple autosomal recessive inheritance.

[Mucosal lesions in the pars esophagus in swine: prevalence and the effect of stress]

Morphological investigations of slaughterhouse material revealed a prevalence of 63% of the sows (n = 224) and 36% of the slaughter pigs (n = 209) with mucosal lesions in the pars oesophagea. The mucosal lesions were composed of severe hyperkeratosis, erosions or ulceration. Microscopic examination showed that hyperkeratosis is attended with parakeratosis. From experiments in a climate controlled pighouse it could be concluded that mixing of unfamiliar pigs resulted in higher prevalences of gastric lesions as compared with keeping the litter together until the end of the experiment (farrow to finish system). There was no relation between gastric lesions and climatic stressors or between gastric lesions and growth and sex of the pigs. When pigs, according to social ranking, were divided in high, middle and low rank it showed that more pigs in the middle-ranked group had gastric lesions. The serum pepsinogen was not related with gastric lesions. There was a tendency that plasma cortisol increased with severity of gastric lesions. There was a strong significant 'litter-effect', which can indicate a genetic predisposition for the development of gastric lesions. Maybe that the presence of mucosal lesions in the pars oesophagea can be used as an objective indicator for welfare in intensive pig husbandry.

Ultrasonographic imaging of a keratoma in a horse

Ultrasonography was used to confirm the tentative diagnosis of keratoma in a horse admitted for chronic progressive lameness. A definitive diagnosis of keratoma traditionally has been diagnosed by history, clinical findings, and radiographic evaluation. Confirmation of the keratoma by use of ultrasonography facilitated the formulation of a treatment plan that resolved the condition.

Ultrastructural findings in congenital anemia, dyskeratosis, and progressive alopecia in Polled Hereford calves

Ultrastructural evidence of dyserythropoiesis was found in ten calves (ages 1 to 16 months) previously diagnosed as having congenital anemia, dyskeratosis, and progressive alopecia. Morphologic abnormalities found in erythroid precursors of all calves were associated with the nucleus. Rubriblast nuclei were irregular with numerous blebs, indentations, and deep clefts. Elongated blebs appeared as satellite nuclei in some sections. Nuclear membranes had numerous defects or gaps, which were frequently present in, but not limited to, recently divided cells. Cytoplasmic material could be found within these gaps and extending into the nucleus. Rubricytes had chromatin that was abnormally condensed and hyperosmiophilic, with numerous translucent vacuoles present. Binucleate rubricytes occurred frequently in affected calves. These changes resemble those of type I congenital dyserythropoiesis in human beings, and we suggest congenital anemia, dyskeratosis, and progressive alopecia of Polled Hereford calves as the appropriate diagnostic terms to describe this disease.

Standing surgical procedures of the foot

Several surgical conditions affecting the foot can be successfully managed with the horse standing. Many factors affect the clinician's choice of whether to perform surgery with the horse standing or anesthetized. Temperament or pregnancy of the horse and economics may influence the decision to perform surgery with the horse standing. This article discusses several foot conditions that can be treated successfully in the ambulatory horse.

Congenital anemia, dyskeratosis, and progressive alopecia in Polled Hereford calves

A new syndrome of anemia, alopecia, and dyskeratosis was identified in Polled Hereford calves in this study. Cutaneous changes included hyperkeratosis and hair loss around the muzzle and ear margins, which progressed to a generalized alopecia and hyperkeratotic dermatitis. Histologically, orthokeratotic hyperkeratosis with dyskeratosis of epidermal and follicular keratinocytes was present. Alopecia was correlated with dyskeratosis of Huxley's layer and an increasing proportion of follicles in the telogen phase of the hair cycle. Dermatitis was characterized by a mild dermal mononuclear cell infiltrate and mild lymphocytic perivascular dermatitis. The anemia present at birth was nonprogressive and was classified as normochromic and normocytic to macrocytic. Reticulocytosis was absent, but bone marrow was markedly hyperplastic. Nuclear cytoplasmic asynchrony of the rubricyte and metarubricyte stages occurred in the bone marrow. Abnormal rubricyte nuclei and maturation arrest at the late rubricyte stage were common. Cytologic features of the erythroid series are similar to those of type I congenital dyserythropoietic anemia of human beings. Genealogic features suggest that this is a primary hereditary defect. The mode of inheritance, however, remains to be determined.

Histopathological development of equine cutaneous papillomas

The histopathological development of equine cutaneous papillomas was studied in 78 warts naturally occurring in 50 one to 3-year-old Thoroughbred or Arab horses and in 54 warts experimentally induced in three 2-year-old Thoroughbreds. Lesions in the natural cases were categorized into three phases, growth, development and regression. Main lesions of the growing phase were marked hyperplasia of the basal cells and mild to moderate acanthosis, hyper- and parakeratosis with a few intranuclear inclusion bodies (IIB) which were positive with anti-bovine papillomavirus serum. In the developing phase, there was prominent acanthosis with cellular swelling and fusion, and marked hyper- and parakeratosis. Many IIB were also present in swollen or degenerative prickle cells and granular cells, with a high degree of parakeratosis in keratinocytes. In the regressing phase, epidermal layers were almost normal with only slight hyperplastic change. However, there was rete peg proliferation downward into the dermis with moderate proliferation of fibroblasts and collagen fibres. In addition, in 10 spontaneous and one experimental wart, the lesions were fibropapillomas and this has never been described in horses previously. It was concluded that papillomas were initiated by basal cell hyperplasia without viral antigen production, with formation of acanthosis and hyper- and parakeratosis with IIB production. These findings were confirmed by examination of the experimental cases on the basis of the gross diameter of the warts.

[Hair alterations in trichophytosis of roe deer--a differential diagnosis for hair parakeratosis]

A rare case of mycosis (ringworm) in a female roedeer is described and compared with parakeratosis of hair. It seems that in game, parakeratosis--as a primary lesion--predisposes to mycosis.

Rate of development of oesophagogastric parakeratosis in the growing pig: some effects of finely ground barley diets, genotype and previous husbandry

The rate of development of parakeratotic lesions in the gastric pars oesophagea was investigated in three experiments using 360 pigs, initially aged 10 to 11 weeks and weighing about 30 kg, of differing genotype and with some differences in previous rearing method, given a diet based on finely ground barley which was known to predispose to lesion formation. Lesions were found in some pigs at 10 to 11 weeks old but the incidence and severity increased progressively indicating development as quickly as one month after first giving the finely ground diet. There were indications that different genotypes and different diets given previously in rearing may have influenced the results obtained. The possible influence of other environmental factors is discussed.

Oesophagogastric parakeratosis in the growing pig: effects of the physical form of barley-based diets and added fibre

In four experiments a total of 288 individually fed pigs were given barley-based diets for about 100 days from about 20 kg liveweight. Fine grinding of barley increased the number and severity of oesophagogastric lesions. Pelleting a diet based on coarsely ground barley had a similar effect. Coarser grinding of the barley and substituting small proportions of oat husk, but not of bran, gave lower incidences and severities of lesions. The performance responses of the pigs differed and give a framework for deciding on the balance to be struck between optimal performance and the risk of lesion development.

Idiopathic benign lichenoid keratosis on the pinna of the ear in four dogs

Histologically, multiple wart-like papules or hyperkeratotic plaques on the ear pinnae from 4 dogs were characterized as idiopathic benign lichenoid keratosis. Common histologic features included a discrete lesion of irregular and papillated epidermal hyperplasia with a moderate diffuse lichenoid interface inflammatory infiltrate consisting of lymphocytes and plasma cells. There was also focal hydropic degeneration of the epidermal basal cell layer, pigmentary incontinence, and mixed orthokeratotic and parakeratotic hyperkeratosis. In all 4 dogs, the pinnal lesions were unilateral and asymptomatic. Complete surgical excision was curative.

Keratomas in horses: seven cases (1975-1986)

The diagnosis of keratoma in 7 horses and their treatment and outcome were evaluated. Horses were 2 to 20 years old, of various breeds, and were intact or castrated males. All were lame, and 6 horses had had previous injuries of the affected hoof that had not responded to prior treatments. Only 1 hoof was affected in each horse. Keratomas were beneath the hoof wall (6 horses) or sole (1 horse). Radiographically, a circular or semicircular defect with a discrete margin was present in the distal portion of the third phalanx in 3 horses. Grossly, keratomas were firm solitary masses (1.5 to 5 cm diameter); gray, tan, or yellow; and oval or conical. Keratomas were excised from beneath the hoof wall by removing a section of hoof wall (5 horses) or by undermining the wall beginning at its junction with the sole (1 horse). A keratoma beneath the sole in 1 horse was excised by excavating the sole to the level of the palmar surface of the third phalanx. Keratoma was verified microscopically by the presence of characteristic rings of squamous epithelial cells with abundant keratin. Purulent exudate and inflammatory infiltrate often were present concurrently, reflecting an associated localized infection. Aftercare included daily application of an antiseptic iodine solution and foot bandages, and shoeing with a treatment plate several weeks after surgery. Hoof and sole defects healed completely between 6 months and 1 year. By 1 year after surgery, 6 horses were sound, and keratoma had not recurred.

Hereditary parakeratosis in shorthorn beef calves

Parakeratosis was diagnosed in 9 Shorthorn beef calves over a 4-year period. When pedigrees of these calves were analyzed, familial associations were strong. Thirty-six coefficients of relationship among all possible combinations of the 9 affected calves ranged from 0.5 to 39.8% and averaged 15.6%. All affected calves were descendants of bull A. Of 9 affected calves, 6 had bull A in their paternal and maternal pedigrees. The 3 remaining affected calves had bull A in their sire's pedigree and were born to 2 full-sib dams. Seemingly, parakeratosis in this Shorthorn herd was hereditary with the mode of inheritance being that of a simple autosomal recessive.

Domestic animals in the elucidation of zinc's role in nutrition

Parakeratosis in swine, a disease that caused severe economic losses in many commercial herds during the late 1940's and early 1950's, was caused by an inadequate intake of zinc. In addition to poor growth, the disease involves primarily the epidermal layer of the skin, which in severe cases becomes thickened and heavily encrusted. Finally, deep fissures develop in the encrusted areas. The low availability of zinc in plant protein sources and the increasing use of soybean meal in practical-type diets during the late 1940's contributed to the increasing incidence of the disease. Excessive levels of calcium also increased the incidence and severity of the disease. Prominent features of zinc deficiency in poultry were failure of normal development of long bones and the occurrence of severe lesions on the feet and legs. As with the pig, the low bioavailability of zinc from plant protein sources led to the observation that practical-type diets were limiting in this metal. Although parakeratosis can be produced in cattle fed diets low in zinc, it does not seem to have been a major nutritional problem in ruminants.

Zinc deficiency in sheep and goats: three field cases

Zinc deficiency was diagnosed in 2 flocks of sheep and a herd of goats. Alopecia and eating of wool were observed. Skin lesions were hyperkeratosis and parakeratosis. Abnormal hoof growth and a closed stance with arched back and bowed hindlimbs were seen. Anorexia, depression, and foot soreness diminished quickly after zinc supplementation. Skin lesions healed and hair and wool growth resumed. A cause for the deficiency could not be established.

The pathology of psittacine beak and feather disease

Psittacine beak and feather disease is characterised by loss of feathers, abnormally shaped feathers and overgrowth and irregularity of the surface of the beak. The disease occurs in a number of psittacine species including the Sulphur-crested Cockatoo, Lovebirds , Budgerigars and Galahs . The abnormal appearance of feathers and beak is due to a dystrophic process within the epidermis of the feather and beak. The process consists of epidermal cell necrosis, epidermal hyperplasia and hyperkeratosis. Many of the feather abnormalities are due to retention of a hyperkeratotic feather sheath. A characteristic microscopic finding is the presence of macrophages containing purple intracytoplasmic inclusions in affected epidermis and feather pulp. The inclusions consist of aggregates of particles 17 to 22 nm in diameter. Similar but smaller inclusions occur in epidermal cells. In addition, non-suppurative inflammation occurs in the feather pulp. The findings are suggestive of a viral infection.

[Acrodermatitis enteropathica--hereditary parakeratosis in calves: contribution to comparative dermatology]

The treatment with oral zinc in the therapy of two zinc deficiency syndromes being identical in calves and man was discovered by veterinarians several years before the introduction of this life-saving therapy in human medicine. The importance of interdisciplinary contacts is emphasized.