References Baird JD, Maxie MG and Harris DJ (1986a) - Insert to Proc 14th Wld Congr Dis Cattle, Dublin Baird JD, Maxie MG Kennedy BW and Harris DJ (1986b) - Proc 14th Wld Congr Dis Cattle, Dublin p 89 Martig J, Tscheedi P, Perritaz C, Tontis A and Luginbilhl H (1982) - Proc 12th Wld Congr Dis Cattle, Amsterdam p 1 I72 Morrow CJ and McOrist S (1985) - Vet Rec 117: 312 Sonada M, Takahaski K , Kurosawa T, Matsukawa D and Chihoya Y (1982) - Proc 12th Wld Congr Dis Cattle, Amsterdam p 1187 Sonada M, Kurosawa T, Takahaski K, Suzuki T, Nakade T, Matsuikawa K and Chihaya Y (1984) - Kachiku Shinryo (J Vet Clin) 247: 3 Watanabe S. Akita T, Itakura C and Goto M (1979) - J Hered 70: 255

(Accepted for publication I1 August 1989)

Neospora caninum infection in dogs

Tasmanian State Institute of Technology, P.O. Box 1214, Launceston,

BL MUNDAY

Tasmania 7250

Zoonotic Diseases Laboratory, USDA, ARS, BARC-East, Beltsville, MD '20705, USA

J P DUBEY

Mt Pleasant Laboratories, P.O. Box 46, Kings Meadows,

Tasmania 7249

RW MASON

In 1984 BjerGs, Mohn and Presthus described an enceph- alomyelitis and myositis in dogs in Norway which was due to a Toxoplasrna-like organism. Subsequently, Dubey et a1 (1988a) reported a similar condition in America and named the or- ganism Neospora caninurn (N. caninum). The purpose of this note is to report the retrospective diagnosis of N. caninurn in Australia. A number of cases were reviewed and slides from 3 were stained immunohistochemically for N. caninurn antigens (Lindsay and Dubey 1989).

In May 1971 a paretic greyhound pup was submitted to the Mt Pleasant Laboratories for examination. There were no significant macroscopic findings, but histological examination of haematoxylin and eosin (H&E) - stained sections revealed multifocal non-suppurative encephalitis associated with Toxo- plasma-like tachyzoites, neuritis and focal myositis. Two H&E sections of cerebrum were destained and restained using the avidin-biotin peroxidase complex (ABC) method. Tachyzoites of N. caninurn were identified in both slides. Two months later another paretic pup from the same litter was presented for examination. This pup had a severe non-suppurative en- cephalitis characterised by intense vascular proliferation nn the affected areas of the brain. Tachyzoites were present in the neuropil and the cytoplasm of unidentified cells. Also, a few degenerate protozoan cysts were detected. No ABC staining was performed on sections from this animal. The lesions in this case were interpreted to be due to reactivation of a quiescent infection.

In the same year an adult dog which had died suddenly was present for necropsy . Microscopic lesions consisted of non-suppurative encephalitis and myocarditis associated with Toxoplasma-like organisms. One H&E slide of cerebrum was destained and restrained by the ABC method revealing the presence of N . caninurn tachyzoites.

In March 1977 the cadaver of a pup, reported to have neurological abnormalities, was submitted for examination. Microscopic lesions consisted of relatively-mild, multi'focal, non-suppurative encephalomyelitis with the presence of thick walled protozoan cysts, often in neurons (Figures 1 and 2). Unstained sections of spinal cord were stained by the ABC method and N. caninurn antigens were demonstrated in tissue cysts (Figure 3).

Veterinarians need to be aware of the presence of N. can- inurn, especially as it can be associated with multiple cases in a litter and consecutive litters may be affected (Dubey et a1 1988b). Also other species may be affected by N. caninurn. Dubey et a1 (1989) reported paresis in calves associated with this organism and Dubey and Lindsay (1989) were able to produce experimental infections and disease in kittens.

Figure 1. Non-suppurative encephalitis associated with N. caninurn tissue cysts (arrows) haematoxylin and eosin x 93. Figure 2. N. caninum tissue cyst in a neuron. Haematoxylin and eosin x 937. Figure 3. N. caninum tissue cyst exhibiting specific staining of cystwall. Avidin-biotin peroxidase complex x 937.

76 Australian Veterinary Journal, Vol. 67, No. 2, February, 1990

References Bjerkis I, Mohn SF and Prethus J (1984) - Z Purasitenkd 70: 271 Dubey JP, Carpenter JL, Speer CA, Topper JM and Uggla A (1988a)

Dubey JP, Hattel AL, Lindsay DS and Topper MJ (1988b) - J A m

Dubey JP, Leathers CW and Lindsay DS (1989) - J Parasitol 75:

Dubey JP and Lindsay DS (1989) - J Parasitol75: 148 Lindsay DS and Dubey JP (1989) - A m J Vet Res: in press

- J Am Vet Med Assoc 192: 1296

Vet Med Assoc 193: 1259

146

(Accepted f o r publication 14 August 1989)

The significance of a major outbreak of quarantinable disease to the Australian horse industries

Australian Quarantine & Inspection Service, RF CLEMENT KA DOYLE

GPO BOX 858, JG MURRAY Canberra, Australian Capital Territory 2601

Department of Primary Industries & Energy,

The Australian horse industries include the following major components: racing and breeding thoroughbreds, gambling on them; harness racing (standardbred), breeding and gambling; equestrian sports and breeding (from Olympic events to local pony clubs); horses used in Australian pastoral industries and breeding; horses for showing and breeding; horses used for personal leisure and breeding; horse exports, and horse pro- ducts from horses killed for human consumption, pet food and other purposes; and horse service industries, including feed, veterinary, equipment, farriers, transport, research, etc.

Information on these industries is fragmented, not easily compiled and thus the analysis presented in Tables 1 , 2, and 3 should be treated as indicative rather than authoritative.

Overall, these horse industries and their associated gambling are major economic and social activities in Australia;

Collectively they contributed about $1.5 billion or 0.5% of Gross Domestic Product in 1987/88 and employ a substantial number of people on a part-time or full-time basis;

The following key points should be noted:

TABLE 1 Numbers of horses in Australia 1988'

Tvoe of Horse Number Thoroughbreds 130,000 Standardbreds 100,000 Equestrian sports 90,000 Pastoral industries 90,000 Leisure and showing (including other breeds such as arabs, appaloosa, quarter horse, stock horses, etc) 240,000 Total domesticated horsest 650,000 to 750,000 Feral horses$ 300,000 to 350,000

Note that because of a lack of detailed published research, figures in this table should be regarded as indicative estimates subject to significant error.

t A range of estimates for total domesticated horses was available (600,000 to 1,000,000) but 650,000 to 750,000 ap- peared t h e most reasonable based on cross comparisons of the components.

$ Estimates provided by the Bureau of Rural Resources, Department of Primary Industries and Energy.

TABLE 2 Statistics of the thoroughbred industry for Australia 1988

Number of races Number of horses racing Prize money Value of yearling auction sales Number of racing clubs Number of venues

25,163 36,405 $146m $73m

500 423

TABLE 3 Economic significance of the Australian Horse Industries'

100,000 Total employment 150,000 Gross turnover, including gambling about $15b Estimated contribution to gross domestic product 1987188 about $1.5b Horses killed for human consumption (1987188) 52,000 Exports of horses, horsemeat and products 1988 $36.3m Horses exported$ purebred 74

other 920 Value of horses exported $1 5m Horses imported$ purebred 1055

other 2970 Value of horses imported $186.6m State government racing tax revenues about $500m Federal tax revenues from horse industries and individuals about $500m

The turnover in employment, GDP and tax revenue figures should be regarded as indicative, because of the lack of detailed research available. While these estimates remain the responsibility of the authors, the assistance given by M r J Hurley and Dr P O'Mara of the Australian Bureau of Agriculture and Resource Economics with the GDP estimate is gratefully acknowledged.

t Ratio of part-time to full-time jobs is high, probably in t h e range 5:l to 1O:l.

$ Export figures exclude short-stay racing horses but these are included in the import statistics.

Full and part time employed in racing?

This contribution to the Australian economy is only marginally smaller in money terms than the contribution from another major group of service industries comprising hotels, clubs and restaurants.

The Australian Bureau of Statistics (ABS 1987) recorded about 400,000 horses on establishments with agricultural ac- tivity at March 1986 with about 28% described as stud horses. ABS estimates are known to seriously underestimate horse numbers for several reasons but principally because many horses reside on establishments which do not undertake agricultural activities. Estimates of total domesticated horses range as high as one million but a figure between 650,000 and 750,000 domesticated horses is more likely with an annual culling rate of about 10%. There is strong anecdotal evidence that the number of these horses has increased in recent years.

In addition, the Bureau of Rural Resources (Dexter e t al 1989) estimates there are 300,000 to 350,000 feral horses in northern Australia. Recent adverse publicity about the transporting of wild horses has seen a decline in their culling. Since feral horse culling is declining, they almost certainly have a negative net worth because of the environmental pro- blems they are creating and the disease risk they represent as an uncontrolled population.

Disease Threats Disease threats include equine influenza, African horse

sickness, borna disease, equine viral encephalomyelitis (including Venezuelan, eastern and western equine encephalomyelitis and and Japanese encephalomyelitis), daurine, epizootic lymphangitis, equine piroplasmosis, glanders, surra, equine viral arteritis, vesicular stomatitis, equine infectious anaemia, equine herpes viruses and con- tagious equine metritis.

African horse sickness (AHS) and Venezeualen equine encephalomyelitis (VEE) are insect-borne diseases and if they became well established, may well be impossible to eradicate. Vaccination would be necessary and costly. Many countries will not accept horses from countries where AHS and VEE are endemic and access to many international events would be denied unless horses completed a period of residency in a third country. Several of the diseases listed also pose serious threats to human life.

Of those listed, the most serious economic threat is from equine influenza which is highly infectious and occurs in many horse raising countries. Australia's import conditions for horses give a high probability that none of these diseases will

77 Australian Veterinary Journal, Vol. 67, No. 2, February, 1990