In this edition

© 2007 The Authors

Australian Veterinary Journal

Volume 85, Nos 1 & 2, January, February 2007Journal compilation © 2007 Australian Veterinary Association

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EDITORIAL

Blackwell Publishing Asia

In this edition

A JACKSON and M REVINGTON

Small Animals

Vaccine protection against feline immunodeficiency virus: setting the challenge

Australian cats have one of the highest rates of infection with felineimmunodeficiency virus (FIV) in the world. FIV is a retrovirusclosely related to human immunodeficiency virus (HIV). It is ableto mutate rapidly and to exist as multiple strains, with implicationsfor diagnosis and vaccination. Subtypes of the virus show geographicclustering, with subtype A predominating in Australia, the UKand western USA; subtype B predominates in parts of Europeand Japan and the eastern USA.

The course of the disease in infected cats is influenced by the cat’sage, health and the dose and strain of the virus. A vaccine againstFIV needs to produce antibodies against a range of viral isolates.The most effective commercial vaccine to date is a whole inacti-vated virus vaccine, however there are concerns that it does notprotect against field strains of the virus, with protection mainlyagainst strains of low virulence. Further, vaccinated cats testpositive on all available FIV serological tests, and antibodies canbe transferred from a vaccinated queen to her kittens. This reviewconcludes that these unresolved issues surrounding FIV vaccinesrequire further research.

Clinical and epidemiological features of canine leptospirosis in North Queensland

In the dog, leptospirosis may manifest as an acute haemorrhagicdisease, as an icteric disease, or as renal disease causing uraemia.This paper is a retrospective study of 40 cases of canine leptospirosisfrom North Queensland, examining clinical signs, serological testsand the outcomes of treatment. Fifteen of the dogs were under1 year, and the median age at diagnosis was 2 years. The diseasewas fatal in 21 dogs, and animals with jaundice, renal failure andmetabolic acidosis were more likely to die. The most commonserovars were

australis

and

zanoni

. The disease appeared to bemost prevalent in the wetter months of the year, mirroring itsoccurrence in the human population in the same region.

Clinical signs in this group of dogs were similar to those causedby different serovars in other geographic regions of Australia. Signswere non-specific, dependent on the severity and duration of thedisease process and reflected multi-system organ failure. Treatmentwas with antibiotics, fluid therapy and anti-clotting agents. Theauthors note that the only vaccine in Australia is against theserovar

icterhaemorrhagiae

; the mode of transmission is likely tobe contact with cattle urine, facilitated by a wet environment.

The surgical management of superficial digital flexor contracture in a Great Dane

A 10-month-old Great Dane had excessive flexion of the digits inits right forepaw, resulting in weight bearing on the dorsal surfaceof the fourth digit. Surgical lengthening of the superficial digitalflexor tendon of digit 4 using a modified Z-tenetomy allowedgreater extension of the digit. The limb was placed in a cast for6 weeks postoperatively. At examination 7 months after surgerythere were no signs of lameness and the dog was bearing weightappropriately on the digital pads.

Angiostrongylus vasorum (French heartworm) in a dog imported into Australia

Infection with

Angiostrongylus vasorum

, commonly known as Frenchheartworm, was diagnosed in a 2-year-old Cocker Spaniel importedfrom the UK into Western Australia. There is only one previousreport in the literature of

A vasorum

infection in Australia. Thedog had a 2 month history of a soft cough, and had more recentlybecome inappetant and lethargic. Multiple nematode larvaewere seen on cytological examination of a fine needle lung lobeaspirate, and stage 1 larvae were present in a faecal sample. Thedog recovered after treatment with fenbendazole.

The authors conclude that suitable intermediate hosts for

A vasorum

may be present in Australia, and importation of dogs from endemicareas without adequate screening may result in its establishmentin this country. As it is,

A vasorum

should be considered in dogsshowing respiratory disease or a coagulopathy that have beenimported from endemic areas.

Cutaneous pyogranuloma in a cat caused by virulent

Rhodococcus equi

containing an 87 kb type 1 plasmid

More commonly a cause of pyogranulomatous pneumonia in foals,

Rhodococcus equi

can also infect cats, causing cutaneous lesions,lymphadenitis, pneumonia and pyogenic lesions of internal organs.

The clinical features of the

R equi

infection in the 2-year-old catin Brazil discussed in this report were similar to those previouslydescribed, with the skin and subcutis of the limbs showing oedema,erythema, abscessation and purulent exudation. A virulent formof

R equi

was identified from cultures of biopsy samples. The catwas euthanased due to a dramatic worsening in its conditionwhilst awaiting the recommended surgical excision of its lesions.It is likely that the cat became infected by direct exposure ofcutaneous injuries to

R equi

from contact with horses or soil fromits rural environment.

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Education, ethics and welfare

Prevalence of occupational exposures and protective practices in Australian female veterinarians

This national cross sectional survey used a self administeredquestionnaire to assess the prevalence of occupational exposuresin Australian female veterinarians. It was part of the Health Riskof Australian Veterinarians project, which was a survey of allgraduates from Australian veterinary schools since 1960.

A total of 5748 letters were sent to all contactable veterinarianswho graduated between 1960 and 2000. A completed question-naire was returned by 1197 females, mean age 35.9 years, range23–78, of whom 85% were in clinical roles, 8% in governmentand 7% others. Responses showed that 82% were exposed toanaesthetic gases, 43% to pesticides on at least a weekly basis and79% were exposed to X-rays. Higher exposures were found inthose who worked at least 45 hours per week, small and mixedanimal practitioners, and recent graduates, although there wasconsiderable variation. The authors concluded that it is essentialthat all veterinarians participate in measures to minimise occupa-tional exposures.

Equine

Suppression of behavioural and physiological oestrus in the mare by vaccination against GnRH

Oestrus in fillies and mares leads to behavioural changes that causeproblems for management. This study, performed in Queenslandand Victoria, included mares that were given one of two treatments,either immunocontraceptive vaccine or adjuvant placebo, in twogroups of 12 at each site. Mares were assessed for 16 weeks forreactions to vaccine, anti GnRH antibody titres, serum progesteroneor 17

β

oestradiol, and ovarian and follicular activity usingtransrectal ultrasonography and palpation. Oestrus behaviourwas assessed with a miniature stallion or Shetland Pony stallion.The study showed that two doses of the vaccine produced antibodyto GnRH and significantly changed the ovarian hormones andoestrus behaviour within 2 weeks of vaccination. The authorsconcluded that the vaccine, which uses a unique proprietaryadjuvant system, was safe and effective.

Detection of viruses in nasal swab samples from horses with acute, febrile, respiratory disease using virus isolation, polymerase chain reaction and serology

The specific initiating cause of most episodes of equinerespiratory disease is often difficult to determine. This focusedstudy was part of a surveillance program by Racing Victoria andthe Centre for Equine Virology including 20 horses with acuteupper respiratory infections. Seventeen viruses were identifiedby PCR and virus isolation, in 12 of 20 horses with acutefebrile respiratory disease. Samples were collected by local equinepractitioners, at their own discretion. The authors noted theconsiderable collaboration that was needed for studies of thistype, as it required time and care on the part of the visitingpractitioners, laboratory processing and follow-up samplecollection.

Disseminated cryptococcosis including osteomyelitis in a horse

Equine cryptococcosis is uncommon. Within Australia, the regionaround Perth in Western Australia has a higher rate of fungalinfection than elsewhere. In this report of a 4-year-old horse fromcoastal Western Australia, multifocal pyogranulomatous pneumonia,osteomyelitis of a rib and proximal phalanx and nodular lesionsof the caecum and colon were due to infection with

Cryptococcusgatti

. This is believed to be the first published report of disseminatedcryptococcal infection with osteomyelitis in a horse. This horsewas euthanased, as treatment would have required protracted andexpensive courses of antifungal medication and surgical debridementof the thoracic lesions. Cryptococcal osteomyelitis also generallyrequires surgical resection, which would not have been feasiblein the proximal phalangeal lesion in this horse.

Telogen defluxion associated with hypersensitivity causing alopecia in a horse

A 2-year-old Thoroughbred horse developed asymmetrical alopecia,skin hypersensitivity and severe ventral and limb oedema, apparentlyas a result of adding a coat conditioning powder to its diet.Microscopic examination of hairs in a pluck sample indicatedtelogen defluxion. Signs abated within 2 to 3 days of withdrawalof the powder from the diet, with full recovery by 4 months afterthe onset of clinical signs.

Wildlife and zoo animals

Mammary and pulmonary carcinoma in a dromedary camel

(Camelus dromedarius)A 15-year-old dromedary camel in an open range zoo developedmammary gland emlargement. A biopsy sample obtained underlight anaesthesia was not diagnostic. When the mammary glandincreased in size 7 months later, the camel was again anaesthetisedto obtain a wedge biopsy, and carcinoma was diagnosed onhistological examination. The animal died with respiratory signs10 days after surgery, and metastatic pulmonary lesions foundat necropsy were thought to be the cause of death. Neoplasiais rarely described in camelids, and the authors speculate as towhether the lack of opportunity to breed contributed to thedevelopment of mammary carcinoma in this animal.

Laboratory animals

Rodentolepis fraterna:

The cause of mortality in a new host, the Spinifex hopping-mouse

(Notomys alexis)The Spinifex hopping-mouse is common in the wild in deserthabitats and is used as a research model. Their endoparasites havenot been described. This short contribution is the first report of

Rodentolepus fraterna

in an index case of a research colony inMacquarie University, New South Wales. Histological investigationof a 120-day-old female mouse showed cestodes in the gastro-intestinal flushes and

R fraterna

scoleces in the lamina propriaof the small intestine, with no lesions in other organs. Faecalflotations showed that other mice in the colony were sheddingeggs of

R fraterna

, as well as those of the pin worm

Aspicularistetraptera

. The authors note that routine health surveys areneeded to reduce the effects of non-native parasites in Australia, and


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that investigators working with the Spinifex hopping-mice need tobe aware of the health risk of the potentially zoonotic

R fraterna.

Production animals

Infectious bovine keratoconjunctivitis antimicrobial therapy

Infectious bovine keratoconjunctivitis, or pink eye, is economicallyimportant in the cattle industry because of inappetence, poorweight gain, cost of repeated drug treatments and decreased milkyield. Although relatively uncommon in Australia, work in theUS suggests that antimicrobial resistance could develop. Thisreview discusses the efficacy data of different subconjunctival,topical and systemic antimicrobials used in Australia.

The authors conclude that the prevention of infectious bovinekeratoconjunctivitis is preferable, such as with segregation, andinsecticides, but if treatment is required, early intervention isneeded. Antimicrobial resistance should be considered if treat-ment failure occurs.

Antimicrobial susceptibility of Australian bovine

Moraxella

isolates

A Short Contribution from the same group evaluates the in vitrosusceptibility of

Moraxella bovis

and

ovis

from naturally occurringinfectious bovine keratoconjunctivitis outbreaks. Ocular swabswere collected by 25 veterinary practises. The study shows thatunlike the situation in the US, there was complete in vitrosusceptibility to all antimicrobials tested. The authors concludeby urging all practitioners to report any consistent failure ofantimicrobials in this condition, so that any emergence of anti-microbial resistance can be monitored.

Multiplex PCR for the detection of

Brucella ovis, Actinobacillus seminis

and

Histophilus somni

in ram semen

The most common causes of ovine epididymitis are

Brucella ovis

,

Actinobacillus seminis

and

Histophilus somni

. They cause con-

siderable losses, and rams cannot enter artificial inseminationcentres in Australia unless they are shown to be free of them.Detection and prompt identification is required for effectivecontrol programs, but microbiological culture methods aredifficult and time consuming. The aim of this study was todevelop a multiplex PCR that could be used instead of or as wellas the standard methods of identification.

A multiplex PCR was developed based on three commercialkits with different reaction conditions, and several DNAextraction methods were tested. The multiplex PCR was ableto identify all three organisms in fresh and preserved semensamples. The authors concluded that although there were twofalse negative results, this assay gives a vast improvement overconventional detection methods, and is quicker than the culturemethods.

History

Epidemic catarrh of sheep: the possible role of black disease

In 1834 a previously unrecognised highly virulent diseaseappeared in sheep in New South Wales. It had a clinical course ofbetween a few hours to three days, and was named epidemiccatarrh, but reports waned after 1870. The cause of the diseasewas not understood, but the current advice was to ‘boil down thewhole flock at once’. It occurred at a time when germ theory was,as the author suggests, at least considered as wild speculation andpathology was rudimentary. This historical review discusses theearly distribution of the disease, its recognition and spread, anddiscusses recent hypotheses about the nature of the disease. Theauthor discusses the hypothesis that the outbreaks were primarilyblack disease, or infectious necrotic hepatitis, with some cases offascioliasis and some coincidental respiratory disease.

doi: 10.1111/j.1751-0813.2006.00104.x


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