The marked increase in kenogen follicles is a strong indication that the induction of the new anagen phase is impaired in hair cycle disorders. The findings in dogs with alopecia X further suggest that premature catagen is also involved in the pathogenesis. Further work to investigate the stem cell compartment and possible initiating factors for the different cycle phases is required to elucidate the exact pathogenesis.

The hair follicle has a lifelong capacity to cycle through recurrent phases of controlled growth (anagen), regression (catagen) and quiescence (telogen), each associated with specific morphological changes. A comprehensive classification scheme is available for mice to distinguish the cycle stages anagen I-VI, catagen I-VIII and telogen. For dogs, such a classification system does not exist, although alopecia associated with hair cycle arrest is common. We applied analogous morphological criteria and various staining techniques to subdivide the canine hair cycle stages to the same extent as has been done in mice. Of all the staining techniques applied, haematoxylin and eosin stain, Sacpic, Masson Fontana and immunohistochemistry for vimentin and laminin proved to be most useful. To evaluate the applicability of our criteria, we investigated skin biopsies from healthy beagle dogs (n=20; biopsies from shoulder and thigh) kept in controlled conditions. From each biopsy, at least 50 hair follicles were assessed. Statistical analysis revealed that 30% of the follicles were in anagen (12% early and 18% late), 8% in catagen (2% early, 5% late and 1% not determinable) and 27% in telogen. Thirty-five per cent of hair follicles could not be assigned to a specific cycle stage because not all follicles within one biopsy were oriented perfectly. In conclusion, this guide will not only be helpful for the investigation of alopecic disorders and possibly their pathogenesis, but may also serve as a basis for research projects in which the comparison of hair cycle stages is essential, e.g. comparative analysis of gene expression patterns. Conflict of interests:The authors declare no conflict of interests.

A n intact, male, stray cat of unknown age was referred to the small animal clinic, University of Bern, Switzerland, in lateral recumbency. On clinical examination, the cat was in a poor nutritional state and severely dehydrated. Small hemorrhages were observed at the nares and medial canthi of the eyes. Heart rate and temperature were normal. Laboratory evaluation supported the clinical impression of dehydration with high hematocrit, high total protein concentration, and mild azotemia with normal urine specific gravity. Thoracic radiographs were normal.On neurologic examination, the cat had a decreased consciousness and nonambulatory tetraparesis, which was more pronounced in the front limbs. Postural reactions were decreased in the hind limbs and nearly absent in the front limbs. Front limb reflexes were decreased, and hind limb reflexes were increased. Muscle tone was increased in the hind limbs and decreased in the front limbs. Neurological deficits and abnormalities in muscle tone were more pronounced on the right side. There was mild generalized muscle atrophy. Examination of cranial nerves was normal. Palpation of the cervico-thoracic vertebrae elicited pain. Impaired consciousness was interpreted as a neurological sign and not attributed to poor nutritional condition. Neuroanatomical localization was multifocal (ie, intracranial and C6-T2). Because of the small hemorrhages in the nose and eyes, trauma or infectious disease were suspected. An ELISA test a was positive for feline leukemia virus (FeLV) antigen and negative for feline immunodeficiency virus. Despite analgesia and treatment with IV fluids the cat did not improve and therefore was euthanized.Necropsy identified a right-sided focal area of reddishtan discoloration and swelling in the cervical intumescence of the spinal cord (Fig 1). Organ samples and the entire central nervous system (CNS) were fixed in 10% neutral buffered formalin. Representative samples of the CNS and internal organs were embedded in paraffin, sectioned at 5 mm and stained with hematoxylin and eosin. Microscopic examination disclosed an encephalomyelitis restricted to the brainstem and cervicothoracic spinal cord. Lesions were most severe in the cervical intumescence (Figs 1, 2A) and tapered off cranially along the cervical spinal cord and brainstem (Fig 2B) into the midbrain and caudally into the first thoracic spinal cord segments. Lesions consisted of microabscesses, characterized by focal aggregates of neutrophils, macrophages, and microglia with rod-shaped nuclei in gray and white matter associated with prominent perivascular cuffs of lymphocytes, macrophages, and few neutrophils (Fig 2B and C). A few inflammatory infiltrates also were observed in the ventral nerve roots of the cervical intumescence. Additional changes included neuronal degeneration and necrosis, neuronophagia (Fig 2D), vasculitis with perivascular hemorrhages, and mild lympho-histiocytic meningitis. Immunohistochemistry was performed with a polyclonal rabbit antibody against Listeriolysin O (1 : 200) b...

Scleromyxedema-the generalized form of lichen myxedematosus, a primary mucinosis-is a rare disease in human patients. It is characterized by dermal mucin deposits, increased numbers of fibroblasts, and variable fibrosis in the absence of thyroid disease. It is accompanied in 80% of cases by a monoclonal gammopathy. To date, scleromyxedema with systemic involvement has not been documented in domestic animals. This is the first report of a scleromyxedema-like syndrome in a cat, which had a substantial deposition of mucin in the dermis of the head and paws with a mild gammaglobulinemia of 2.25 g/dl (reference range, 1.39-2.22 g/dl). At necropsy, multiple nodules of connective tissue intermingled with mucin deposits were conspicuous on the surface of thoracic and abdominal organs. Such severe systemic accumulations of mucin have not been reported in human or veterinary medicine.