CASE REPORT

A hair abnormality in Abyssinian cats G. T. Wilkinson and T. S. Kristensen"

Department of Companion Animal Medicine and Surgery, School of Veterinary Science, University of Queensland, St Lucia, Brisbane 4067, Australia and *Skovlunde Dyreklinik, Skovlunde Byvej 53, 2740 Skovlunde, Copenhagen, Denmark

Iournal of Small Animal Practice (1989) 30, 27-28

ABSTRACT An abnormality of the hair shaft of the whiskers

and guard hairs of Abyssinian cats, consisting of an onion-shaped swelling, usually situated at the tip of the hair but occasionally at other sites along the hair shaft, is reported. Where the abnormality occurs in the guard hairs i t imparts a rough, brittle and lustreless appearance to the coat. Microscopi- cally the epidermis, dermis and hair follicles and appendages appear normal. The condition has been seen in two Abyssinian cats in Denmark and one in Australia.

INTRODUCTION Apart from acquired alterations in diameter,

pigmentation and strength of the hair induced by nutritional and hormonal changes, structural abnormalities of the hair shaft of small animals have rarely been reported. A search of the literature from the previous 30 years revealed only a descrip- tion of trichorrhexis nodosa (Kral and Schwartz- man 1964) and a case of pili torti in two littermate kittens (Geary and Baker 1986). The present com- munication records the occurrence of a distinctive abnormality of the hair shaft in male and female littermate Abyssinian cats in Denmark and a female Abyssinian in Australia.

CASE HISTORY Copenhagen

A 14-month-old entire male Abyssinian cat was presented with the complaint that the whiskers and the hair coat had an abnormal appearance. On examination it was seen that on almost every whisker and guard hair there was a bulge in the hair shaft, just visible to the naked eye, on the tip of the hair (Fig 1). On the whiskers there was occasional- ly a second bulge at various sites along the hair shaft. Microscopical examination showed that the bulge consisted of an onion-shaped expansion of the medulla (Fig 2) . The hair coat was rough to the touch and appeared bristly and lustreless (Fig 3). The condition had been treated by another veter- inarian with 125 mg griseofulvin daily for 25 days with no observable change.

Two months later the cat was referred to the Royal Veterinary College, Copenhagen. Tests for dermatophyte infection were negative. Cytogene- tic studies showed a normal complement of chromosomes with no structural abnormalities. No

FIG 1. The Danish cat showing the abnormality on some of the whiskers

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G. T. WILKINSON AND T. s. KRISTENSEN

FIG 3. The coat of the Danish cat showing the rough. bristly appearance

reason for the hair anomaly could be found and a literature search failed to throw any light on the problem.

The cat was castrated three months later when a skin biopsy was obtained and blood taken for an ELISA for feline leukaemia virus infection, which proved negative. The skin biopsy showed an essen- tially normal appearance, although the dermal collagen appeared somewhat fragmented. (Clini- cally there was no evidence of skin hyperextensi- bility or fragility and the skin and subcutaneous tissues appeared macroscopically normal.) The hair follicles and their appendages were normal in appearance.

It was learned later that a litter sister of the affected cat showed the same hair abnormality but to a lesser degree.

Brisbane

While the senior author was discussing the hair problem with an Australian colleague who breeds Abyssinians, she remarked that one breeding queen showed the same abnormality, but in this case it was entirely confined to the whiskers. This was confirmed on examination of the queen, sever- al whiskers showing an identical onion-shaped enlargement at the hair tip. None of the guard hairs appeared to be affected and the coat was of normal appearance and consistency.

DISCUSSION It is difficult to explain the mechanism under-

lying the formation of this abnormality, especially where it occurred in the mid-shaft position. The hair shaft anomaly most resembling the one re- ported here is trichorrhexis nodosa, which is an acquired defect in which solitary nodules form at the end or along the hair shaft, followed by longitudinal splitting of the shaft through the nodules from a short distance each side of them. This produces an appearance as if the nodules consisted of two small round brushes pressed end to end. Similar splitting of the hair at the tip produces a frayed appearance. The aetiology of the disorder is unknown, but it has been suggested that damage to the hair cortex by chemical agents or mechanical factors, such as harsh brushing or rubbing, results in prolapse of the medulla, forma- tion of the nodules and subsequent splitting of the hair shaft (Kral and Schwartzman 1964). A similar pathogenesis for the Abyssinian abnormality is unlikely as the condition was noted in kittens, whiskers and guard hairs are not subjected to excessive grooming, rubbing or application of chemicals, and the hair shaft is not split.

Examination of the pedigrees of the Danish and Australian cats revealed some common ancestors. This is not surprising considering the links be- tween the UK, Europe and Australia in Abyssinian breeding stock. Food shortages and other problems almost wiped out the Abyssinian breed in Britain during World War 11. (It has been stated that only a total of 11 breeding queens remained in the coun- try at the end of the war). A considerable amount of inbreeding must have occurred during the post- war replenishment years. A number of Abyssi- nians were exported to Europe and Australia, which has historically obtained its breeding stock from the UK, during the 1950s. In a reverse exchange, following severe losses in British Abyssinian breeding stock due to feline leukaemia virus infection during the 1960s and 1970s, breed- ers imported cats from Europe. So Abyssinians in Britain, Denmark and Australia probably share a considerable common ancestry. It would be of interest if all Abyssinians presented at cat shows in the three countries could be examined for the presence of this hair abnormality to determine the prevalence of the condition within the breed.

REFERENCES GEARY, M. R. & BAKER, K. P. (1986) The ocxurrence of pili torti i n

a litter of kittens in England. journal o i Small Animtrl Practice 27, 85-88

KRAL. F. & SCH~ARTZMAN, R . M. (1964) Disorders ofthe Hair. In: Veterinary and Comparative Dermatology. Philadelphia. 1, H. Lippincott. p 189

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