Epidemiological and diagnostic features of canine and feline dermatophytosis in the United Kingdom from 1956 to 1991.

Between 1956 and 1991, 8349 samples from dogs and cats were received for investigation of suspected dermatophytosis, and 1368 (16 per cent) yielded positive cultures. Cats had a significantly higher proportion of positive cultures (26 per cent) than dogs (10 per cent), and of these Microsporum canis accounted for 92 per cent in cats and 65 per cent in dogs. The other isolates were diverse but mainly sylvatic dermatophytes, and M gypseum was isolated on only four occasions. Different breeds of dog and cat had significantly different prevalences of infection, with pedigree and long-haired cats, and Jack Russell and Yorkshire terrier dogs having a particularly high proportion of positive cultures. Animals less than one year old appeared to be predisposed to infection, but there was no apparent sex predisposition and no conclusive evidence of any seasonal variation in the incidence of the disease. In comparison with the results of dermatophyte culture, examination under Wood's lamp had a positive predictive value of 90 per cent and a negative predictive value of 94 per cent in determining M canis infection, and direct microscopy had positive and negative predictive values of 93 per cent in determining the presence of dermatophytosis. However, cultural examination alone was insufficient for the diagnosis of dermatophytosis owing to the occurrence of false positive and false negative results.

Prevalence of chlamydia, toxoplasma, toxocara and ringworm in farm cats in south-west England.

The prevalence of infection with Chlamydia psittaci, Toxoplasma gondii, Toxocara cati and Microsporum canis was examined in 51 cats on 22 sheep farms in the Bristol area. Serum antibody to C psittaci and T gondii was present in 45 per cent and 47 per cent of cats, respectively. At the time of sampling C psittaci was isolated from 6 per cent of the cats, T cati was identified in 63 per cent of faecal samples but neither T gondii nor M canis was isolated. When examined according to the farm of origin, 22.7 per cent of farms had cat populations with no evidence of infection with C psittaci or T gondii. Of the remainder, 45.5 per cent supported cat populations with evidence of both infections and 31.8 per cent had evidence of T gondii infection alone. None of the farms had cat populations with evidence of C psittaci infection alone. Two of the cats infected with C psittaci were excreting viable organisms in the faeces. The possible significance of this to the epidemiology of ovine enzootic abortion is discussed.

An investigation into the aetiology of 'wool slip': alopecia in ewes which are housed and shorn in winter.

Alopecia in housed ewes which are shorn in winter, 'wool slip', was investigated by taking wool and blood samples, skin scrapings and biopsies from affected and unaffected animals. Epidemiological information was also obtained from farm records, and reports from a local weather station. No pathological lesions were seen and no ectoparasites or forage mites were seen in wool samples or skin scrapings. The plasma zinc and copper concentrations of both groups were within the normal range but the copper concentrations were significantly lower in the unaffected animals. There was no difference between the prevalence of the disease in ewes of different breeds or between those producing single or twin lambs. A comparison of the mean temperatures during years of summer and winter shearing suggested that cold stress alone was not involved. Skin biopsies revealed that the wool follicles of affected animals were in an early growth phase (anagen) whereas those of unaffected animals were in the inactive phase (telogen). The clinical and histological signs of the disease were similar to those seen experimentally when corticosteroids are used as chemical depilatory agents. It is suggested that wool slip is due to the high levels of corticosteroids which occur as a result of the combination of housing and shearing and on this basis methods of control are proposed.

Parasitic laryngeal papillomatosis in a horse.

Papillomatous lesions intruding into the laryngeal airway were identified in an imported polo pony during a routine neurological examination for partial quadriplegia. Histological examination established a diagnosis of laryngeal besnoitiosis but it is unlikely that the laryngeal parasitism was associated with the cerebellar neuropathy which was also present.

Parasitic liver damage in lambs with particular reference to the migrating larvae of Ascaris suum.

It has been suggested that the larvae of the pig nematode Ascaris suum is a possible cause of rejection of lambs' livers in the abattoir. However, this assertion was not substantiated in an experimental study in which lambs were dosed with infective A suum eggs. This produced, at the worst, small trivial lesions (up to 2 mm diameter) which would probably have been missed at meat inspection under commercial conditions. No evidence of ascarid lesions was observed in the livers of 5873 lambs and hoggs slaughtered between June and August. The most important causes of rejection were lesions caused by Cysticercus tenuicollis and migrating Fasciola hepatica, and these accounted for 90 and 8 per cent, respectively, of 1337 livers rejected either totally or partially by the meat inspectors.

Glycosaminoglycans in the touch corpuscle of the dog.

Alcian Blue staining of the touch corpuscle of dog skin indicates that glycosaminoglycans are present as globular masses in some of the basal cells and are also seen in high concentration in the connective tissue core. The function of these basal cells is not clear but they may be responsible for the production of the large amount of glycosaminoglycan present in the underlying dermis.

Skin ulceration associated with herpesvirus infection in cats.

Three cases of skin ulceration in cats are described. Herpesvirus was isolated from the ulcers. Treatment of one case with antibiotics and an antiviral agent was successful. The significance of the viral isolate is discussed.