Viruses of lower vertebrates

Viruses of lower vertebrates recently became a field of interest to the public due to increasing epizootics and economic losses of poikilothermic animals. These were reported worldwide from both wildlife and collections of aquatic poikilothermic animals. Several RNA and DNA viruses infecting fish, amphibians and reptiles have been studied intensively during the last 20 years. Many of these viruses induce diseases resulting in important economic losses of lower vertebrates, especially in fish aquaculture. In addition, some of the DNA viruses seem to be emerging pathogens involved in the worldwide decline in wildlife. Irido-, herpes- and polyomavirus infections may be involved in the reduction in the numbers of endangered amphibian and reptile species. In this context the knowledge of several important RNA viruses such as orthomyxo-, paramyxo-, rhabdo-, retro-, corona-, calici-, toga-, picorna-, noda-, reo- and birnaviruses, and DNA viruses such as parvo-, irido-, herpes-, adeno-, polyoma- and poxviruses, is described in this review.

Heritability estimations for diseases, coat color, body weight, and height in a birth cohort of Boxers

OBJECTIVE

To obtain heritability estimates for diseases and characteristics in Boxers.

ANIMALS

Birth cohort of 2,929 purebred Boxers from 414 litters.

PROCEDURE

Heritability estimates were determined for cheiloschisis-palatoschisis, cryptorchidism, epilepsy, stifle disorders, cardiac disorders, coat color, birth weight, and adult weight, and height. Binary traits were analyzed by use of a mixed-effects probit model. Some traits also were analyzed by use of a model that postulated monogenic inheritance. Full pedigree analyses were performed. Variation in incidences of disease among clusters of related dogs was evaluated.

RESULTS

Heritability estimates were virtually zero for cardiac disorders, medium (0.17 to 0.36) for most other traits, and high (> 0.55) for coat color, birth weight, and adult height. Litter effects and risk factors affected cheiloschisis-palatoschisis, heart murmur, coat color, broadly defined epilepsy, and adult weight. Litter effects may be attributable to common environmental effects for littermates but also may be attributable to dominance variation caused by a recessive gene. Heritability estimates increased when stricter definitions for epilepsy and stifle disorders were used. The monogenic model did not reveal higher heritability estimates for 6 traits analyzed. Incidences for white coat differed significantly for 10 familial clusters, confirming high heritability and effects of familial lineage.

CONCLUSIONS AND CLINICAL RELEVANCE

Results indicate that genetic improvement of most traits should be feasible, except for cardiac disorders. However, because most traits are influenced by environmental effects as well as genetic effects, genetic counseling based on polygenic inheritance and use of familial information rather than strict exclusion of parents is preferred.

Efficacy of computerized discrimination between structure-related and non-structure-related echoes in ultrasonographic images for the quantitative evaluation of the structural integrity of superficial digital flexor tendons in horses

OBJECTIVE

To evaluate effectiveness of computerized discrimination between structure-related and non-structure-related echoes in ultrasonographic images for quantitative evaluation of tendon structural integrity in horses.

SAMPLE POPULATION

4 superficial digital flexor tendons (2 damaged tendons, 2 normal tendons).

PROCEDURE

Transverse ultrasonographic images that precisely matched histologic sections were obtained in fixed steps along the long axis of each tendon. Distribution, intensity, and delineation of structure-related echoes, quantitatively expressed as the correlation ratio and steadiness ratio , were compared with histologic findings in tissue that was normal or had necrosis, early granulation, late granulation, early fibrosis, or inferior repair.

RESULTS

In normal tendon, the even distribution of structure-related echoes with high intensity and sharp delineation yielded high correlation ratio and steadiness ratio. In areas of necrosis, collapsed endotendon septa yielded solid but blurred structure-related echoes (high correlation ration and low steadiness ratio). In early granulation tissue, complete lack of organization caused zero values for both ratios. In late granulation tissue, reorganization and swollen endotendon septa yielded poorly delineated structure-related echoes (high correlation ratio, low steadiness ratio). In early fibrosis, rearrangement of bundles resulted in normal correlation ration and slightly low steadiness ratio. In inferior repair, the almost complete lack of structural reorganization resulted in heterogeneous poorly delineated low-intensity echoes (low correlation ratio and steadiness ratio).

CONCLUSIONS AND CLINICAL RELEVANCE

The combination of correlation ratio and steadiness ratio accurately reflects histopathologic findings, making computerized correlation of ultrasonographic images an efficient tool for quantitative evaluation of tendon structural integrity.

Babesia leo n. sp. from lions in the Kruger National Park, South Africa, and its relation to other small piroplasms

Babesia leo, a small piroplasm isolated from lions in South Africa is described as a distinct species based on a phylogenetic analysis of the 18S rRNA gene. Intraerythrocytic trophozoite and merozoite stages of B. leo are morphologically indistinguishable from other small piroplasms of felids. Previous studies showed that B. leo was biologically and antigenically distinct from B. felis, which is known to infect wild and domestic felids in South Africa. Molecular characterization showed strong support for the phylogenetic seperation of B. leo as a distinct species from B. felis and other felid piroplasms. Phylogenetic analysis also showed that Babesia microti and all of the felid piroplasms from Africa with known 18S rRNA gene sequences available, including B. leo, formed a single, separate clade, sister to the other babesial and theilerial piroplasm parasites.

Evaluation of a latex agglutination kit (Virogen Rotatest) for detection of bovine rotavirus in fecal samples

The performance of the Virogen Rotatest latex agglutination test (LAT) was evaluated for detection of bovine rotavirus antigen. Sixty-three fecal samples from diarrheic calves were collected from November 1999 to May 2000 and screened by LAT, the Rotazyme II enzyme-linked immunosorbent assay (ELISA), and virus isolation (VI) followed by an anti-rotavirus fluorescent-antibody (FA) test to detect the presence of group A rotavirus antigen. Of the 63 samples screened by VI-FA, 33 (58%) tested positive for rotavirus antigen. When the results from the LAT were compared to those from VI-FA, the "gold standard" for detection of bovine rotavirus in fecal samples, the sensitivity and specificity were found to be 87.8 and 73.3%, respectively. Latex agglutination compared with ELISA (the reference method) showed 100% sensitivity and 96.3% specificity, and when ELISA was compared with VI, the sensitivity was 84.8% and the specificity was 73.3%. Latex agglutination is easy to perform in a short time and does not require expensive equipment or skilled personnel, and the reagents have long shelf lives. These factors make the LAT suitable and highly efficient for use in a clinical laboratory as a rapid screening test for bovine rotavirus.

Dog ecology and demography information to support the planning of rabies control in Machakos District, Kenya

A study of 150 dog-owning households from six randomly selected sublocations was conducted in Machakos District, Kenya. Initially, all households were visited to collect information on dog ecology and demography based on WHO guidelines and to collect serum for rabies antibody detection. A second visit was made 1 year later, to obtain follow-up data on births, deaths, dog movements and other events since the first visit. Dog ownership was common, with a range of 53--81% (mean=63%) of households owning dogs in the six sublocations. Dog density for the five more rural sublocations ranged from 6 to 21 dogs km(-2) and for the peri-urban sublocation was 110 dogs km(-2). The dog population was estimated to be growing at 9% p.a. (95% C.I. 4--14%). This growth was a function of very high fecundity (1.3 females per female per year) more than compensating for high mortality, particularly among females. Life expectancy from birth was 3.5 years for males and 2.4 years for females. Half the dogs at any one time were less than 1 year of age. All dogs, by design of the study, were owned. Of these, 69% were never restricted and roamed freely to forage for food and mix with other dogs. Only a small proportion of dogs (5%) were fed commercial dog food. Most households reported observing dogs scavenging their garbage, including: their own dogs (81%), their neighbours' dogs (75%) and unknown dogs (45%). Only 29% of dogs at least 3 months of age were reported to be vaccinated against rabies. The proportion vaccinated varied widely between sublocations (5--68%); 48% of dogs reportedly vaccinated had detectable antibodies, 31% at or above levels considered to indicate seroconversion. The proportion of dogs with detectable antibodies declined according to the time since last vaccination (55% if vaccinated < or = 1 year, 47% < or = 2 years and 36% > 2 years); 20% of dogs reported not to have been vaccinated had detectable rabies antibody. Compared to other dog populations in rural eastern and southern Africa, Machakos District has a high density of dogs. The Machakos dog population is growing, highly dynamic, poorly supervised and inadequately vaccinated against rabies. The main implication for rabies control is that adequate vaccination coverage is unlikely to be achieved, even under optimal delivery, using the current strategy of annual vaccination of dogs older than 3 months.

The role of veterinary epidemiology in the study of free-roaming dogs and cats

Free-roaming dogs or cats are domestic dogs and cats that are not confined to a yard or house. Free-roaming dogs and cats have long caused major public-health problems and animal-welfare concerns in many countries. Free-roaming dogs have been considered to be more of a problem than cats for several reasons, but the literature addressing dogs focuses primarily on their role in rabies spread and control. Free-roaming cats are becoming more of an issue in countries where free-roaming dog problems are coming under control. The change in perception of pets, beyond their value as a commodity, has also contributed to the increase in concern and attention focused on free-roaming dogs and cats. Epidemiologists have contributed much to these studies of these populations and have potential to contribute even more. The epidemiologic methods and approaches, the experience of epidemiologists in interdisciplinary teams and the importance of considering the separate sub-populations in study design and analysis all are critical in designing and evaluating interventions for free-roaming dogs and cats. In this paper, I will (1) describe a set of useful definitions regarding free-roaming dogs and cats, (2) summarize past and present topics of study in free-roaming dogs and cats, using selected examples, (3) describe the limitations of existing work and how epidemiologists might strengthen and improve this work, and (4) outline areas needing more attention by epidemiologists and why these are important.

Abnormalities of hoof growth and development

The normal development of the horn capsule (epidermis), with its dermal support (corium), is described. Abnormalities of horn growth may be caused by changes in blood flow (laminitis), the biomechanics of weight bearing, heritable developmental conditions, and other changes of unknown cause.

Significance of serological testing for ehrlichial diseases in dogs with special emphasis on the diagnosis of canine monocytic ehrlichiosis caused by Ehrlichia canis

Dogs are susceptible to a number of ehrlichial diseases. Among them, canine monocytic ehrlichiosis is an important and potentially fatal disease of dogs caused by the rickettsia Ehrlichia canis. Diagnosis of the disease relies heavily on the detection of antibodies and is usually carried out using the indirect immunofluoresence antibody (IFA) test. The IFA test may be confounded by cross-reactivities between a number of the canine ehrlichial pathogens. This article presents a review of the ehrlichial diseases affecting dogs with reference to their immune responses, host specificities, cross-reactivites and diagnosis. Diagnostic means such as Western immunblot, dot-blot and PCR are discussed. The use of the IFA test as a diagnostic means for E. canis is presented along with its potential pitfalls. The review emphasizes that the disease process, cross-reactivites with other ehrlichial species, multiple tick-borne infections and persistent IFA antibody titers post-treatment, should all be considered when interpreting E. canis serological results.

Analgesia and analgesic techniques

In recent years, there has been a great increase in our understanding of pain mechanisms and our awareness of pain in small animals. Despite increased knowledge, many animals still go undertreated or untreated. Small exotic animals are a unique group of patients, and can prove challenging for the practitioner concerned with their welfare. This article reviews the process of nociception and how one can intervene in the pain pathway. Newer analgesic drugs are discussed, along with some novel administration techniques that can be adapted for small mammals. Ketamine has been regarded primarily as a chemical restraining agent, but new information reveals that it may have an important place in pain management.

Individual intake and antiparasitic efficacy of free choice mineral and fenbendazole in range calves

The current study was conducted to assess the feasibility of fenbendazole (FB) administration to steers in a free choice mineral supplement. Provision of free choice FB reduces the need for handling of animals as well as decreases the level of animal parasitism. Two separate trials were conducted using 400 +/- 19 kg Holstein steers (n=14 and 17) during the months of July and August. Each steer was tagged with a unique electronic identification (EID) ear tag and randomly allocated into one of two groups. The tags worked in conjunction with a mineral feeder equipped with a load cell by registering the steer's EID number every time the animal entered the electromagnetic field. Individual daily mineral intake and feeding times were determined over two 8-day periods of non-medicated mineral (no FB), separated by a 14-day period of medicated mineral (0.55% FB). Fecal samples were collected at the beginning and end of each trial period and were analyzed for gastrointestinal nematode eggs and Giardia cyst. There was a consistently high level of attendance for the entire experimental period, with the exception of the first six days of the adaptation period. There were three preferential times for visiting the mineral feeder, approximately 07:00, 12:00 and 18:00 h. Individual daily mineral and FB intake was 229 +/- 27.21 g/day and 2 +/- 0.14 mg/kg BW/day, respectively, for the 14-day drug delivery period. The levels of fecal nematode eggs and Giardia cysts decreased significantly (<0.01) between pre- and post-sampling, with reductions of 92% for nematode eggs and 85% for Giardia cysts. Free choice medication for the control of gastrointestinal parasites is potentially effective, provided that the appropriate drug concentration, adaptation period, intake level and duration of treatment is utilized.

Primate anesthesia

This article provides an update on some of the recent advances in primate anesthesia. It focuses in particular on some of the newest information available regarding the effects of opioids and alpha-2 agonists in primates, and how these effects are different from what we might expect in other companion animals. It reviews the important properties of the latest induction and inhalation agents, and stresses the need for continuous monitoring of the anesthetized patient.

Molecular epidemiology of tuberculosis and other mycobacterial infections: main methodologies and achievements

In the last decade, DNA fingerprint techniques have become available to study the interperson transmission of tuberculosis and other mycobacterial infections. These methods have facilitated epidemiological studies at a population level. In addition, the species identification of rarely encountered mycobacteria has improved significantly. This article describes the state of the art of the main molecular typing methods for Mycobacterium tuberculosis complex and non-M. tuberculosis complex (atypical) mycobacteria. Important new insights that have been gained through molecular techniques into epidemiological aspects and diagnosis of mycobacterial diseases are highlighted.

From Animal to Man: Tinea Barbae

Dermatophytic fungi cause human infection worldwide. One clinical syndrome--tinea barbae, which closely resembles tinea capitis--is a trichophytosis involving the beard and mustache areas of the face. The fungal agents responsible for tinea barbae (Trichophyton verrucosum and Trichophyton mentagrophytes) are contracted through occupational exposure to animals infected with zoophilic dermatophytes. Tinea barbae may be confused with other facial infections, especially those caused by Staphylococcus aureus or other facial dermatophytes (usually anthrophilic). In an afebrile patient without leucocytosis, a distinctive facial lesion, called a kerion, can be the essential diagnostic finding. Diagnosis requires suspicion based on appropriate exposure. Definitive diagnosis requires a combination of clinical examination, direct microscopic examination using potassium hydroxide, and culture confirmation. Topical treatment is not effective. Oral therapy with an antifungal (eg, terbinafine) or an azole is recommended. This article reviews these factors, as well as germane epidemiologic and prevention measures.

Babesiosis

Babesiosis is an emerging, tick-transmitted, zoonotic disease caused by hematotropic parasites of the genus Babesia. Babesial parasites (and those of the closely related genus Theileria) are some of the most ubiquitous and widespread blood parasites in the world, second only to the trypanosomes, and consequently have considerable worldwide economic, medical, and veterinary impact. The parasites are intraerythrocytic and are commonly called piroplasms due to the pear-shaped forms found within infected red blood cells. The piroplasms are transmitted by ixodid ticks and are capable of infecting a wide variety of vertebrate hosts which are competent in maintaining the transmission cycle. Studies involving animal hosts other than humans have contributed significantly to our understanding of the disease process, including possible pathogenic mechanisms of the parasite and immunological responses of the host. To date, there are several species of Babesia that can infect humans, Babesia microti being the most prevalent. Infections with Babesia species generally follow regional distributions; cases in the United States are caused primarily by B. microti, whereas cases in Europe are usually caused by Babesia divergens. The spectrum of disease manifestation is broad, ranging from a silent infection to a fulminant, malaria-like disease, resulting in severe hemolysis and occasionally in death. Recent advances have resulted in the development of several diagnostic tests which have increased the level of sensitivity in detection, thereby facilitating diagnosis, expediting appropriate patient management, and resulting in a more accurate epidemiological description.

True dermoid cyst in a Rhodesian ridgeback

A case of a true dermoid cyst in a Rhodesian ridgeback is described. The mass was located in the dorsal cervical midline at the level of the first cervical vertebra, and was resected surgically. In contrast to other types of dermoid sinus described in the literature, the mass did not have a tract connecting it to, nor an opening on to, the surface of the skin. A diagnosis of true dermoid cyst was made.

Babesiosis

Babesiosis is an emerging, tick-transmitted, zoonotic disease caused by hematotropic parasites of the genus Babesia. Babesial parasites (and those of the closely related genus Theileria) are some of the most ubiquitous and widespread blood parasites in the world, second only to the trypanosomes, and consequently have considerable worldwide economic, medical, and veterinary impact. The parasites are intraerythrocytic and are commonly called piroplasms due to the pear-shaped forms found within infected red blood cells. The piroplasms are transmitted by ixodid ticks and are capable of infecting a wide variety of vertebrate hosts which are competent in maintaining the transmission cycle. Studies involving animal hosts other than humans have contributed significantly to our understanding of the disease process, including possible pathogenic mechanisms of the parasite and immunological responses of the host. To date, there are several species of Babesia that can infect humans, Babesia microti being the most prevalent. Infections with Babesia species generally follow regional distributions; cases in the United States are caused primarily by B. microti, whereas cases in Europe are usually caused by Babesia divergens. The spectrum of disease manifestation is broad, ranging from a silent infection to a fulminant, malaria-like disease, resulting in severe hemolysis and occasionally in death. Recent advances have resulted in the development of several diagnostic tests which have increased the level of sensitivity in detection, thereby facilitating diagnosis, expediting appropriate patient management, and resulting in a more accurate epidemiological description.

Between and within breed variation in lamb survival and the risk factors associated with major causes of mortality in indigenous Horro and Menz sheep in Ethiopia

Data collected on 3256 lambs born to Horro and Menz breed ewes single-sire mated to 71 rams at the International Livestock Research Institute (ILRI) Debre Berhan station between September 1992 and June 1996 were analysed for rates of survival and growth from birth to weaning. A significantly lower proportion of Menz lambs died before 1 year of age (28%) than the Horro lambs (59%). Least squares means for pre- and post-weaning mortality were 8.8 and 19.3%, respectively in Menz, and 25.3 and 34.2% for Horro sheep. Major causes of death were similar in Horro versus Menz lambs and were pneumonia (53 vs. 54%, respectively), digestive problems (14 vs. 12%), endoparasite infections (9 vs. 13%), starvation-mismothering-exposure (SME) complex (10 vs. 7%) and septicemia (3 vs. 2%). Relationships among causes of mortality with breed, birth weight (BWT), season of birth, parity, litter size and lamb health category (number of times a lamb was sick between birth and 1 year of age) were determined. The impact of these factors on mortality varied with lamb age. Lambs that were born with <2kg BWT had a greater risk of dying from any cause except pneumonia. But, even though Horro lambs were heavier than Menz at birth (2.4 vs. 2.1kg, respectively), twice as many died before 1 year of age. The cause of mortality was further influenced by season of birth, lamb sex and health category. In addition, sires were a significant source of variation for progeny survival at 6, 9 and 12 months of age, but not at the younger ages. The best and worst Horro ram sired progeny groups that had mortality rates up to 1 year of age of 22 vs. 80%, respectively. The same estimates in Menz rams were 11 and 48%, respectively. Reduced mortality rate would significantly increase lamb output. However, isolated efforts to solve this problem are likely to have limited impact. Instead, an integrated approach to minimise the impact of underlying factors is advocated. Farm (animal) management routines that could be introduced in the short or longer term are discussed.

Comparative study of propofol or propofol and ketamine for the induction of anaesthesia in dogs

The effects of propofol alone or propofol and ketamine for the induction of anaesthesia in dogs were compared. Thirty healthy dogs were premedicated with acepromazine and pethidine, then randomly allocated to either treatment. Anaesthesia was induced with propofol (4 mg/kg bodyweight intravenously) (group 1), or propofol and ketamine (2 mg/kg bodyweight of each intravenously) (group 2). Anaesthesia was maintained with halothane, delivered in a mixture of oxygen and nitrous oxide (1:2) via a non-rebreathing Bain circuit. Various cardiorespiratory parameters were monitored at two, five, 10, 15, 20, 25 and 30 minutes after induction, and the animals were observed during anaesthesia and recovery, and any adverse effects were recorded. During anaesthesia, the heart rate, but not the systolic arterial pressure, was consistently higher in group 2 (range 95 to 102 beats per minute) than in group 1 (range 73 to 90 beats per minute). Post-induction apnoea was more common in group 2 (11 of 15) than in group 1 (six of 15). Muscle twitching was observed in three dogs in each group. Recovery times were similar in both groups. Propofol followed by ketamine was comparable with propofol alone for the induction of anaesthesia in healthy dogs.

Productive performance of Dorper sheep

The Dorper is a hardy South African composite breed, derived from a cross between the Black-headed Persian and the Dorset Horn. Dorpers are regarded as early-maturing, and ewes lambed at an age of 1 year in one study. Age at first lambing was higher in other literature sources cited. The fertility of Dorper ewes was approximately 0.90 ewes that lambed per ewe mated, with a litter size ranging from 1.45 to 1.60. The gestation length of Dorper ewes was approximately 147 days, while they were reported to start cycling as soon as 52 days after parturition. The pre-weaning survival of Dorper lambs was cited at approximately 0.90. Overall reproduction rate of Dorpers ranged from 0.99 to 1.40 lambs weaned per ewe mated, while it exceeded 1.40 lambs weaned per ewe mated per annum under accelerated mating conditions. Dorper lambs gained from 0.24 to 0.28kg per day under vastly different environmental conditions. When weaned early at 2-3 months of age, post-weaning gains in excess of 0.18-0.20kg per day were recorded. At slaughter, Dorper lambs had dressing percentages of approximately 50%. Two divergent genotypes in the breed (with a hairy or a woolly fleece cover) were evaluated under natural pasture conditions. No conclusive advantage in favour of either genotype could be demonstrated as far as productive traits were concerned. It was concluded that the breed adapts well to a wide variety of environmental conditions. In view of the scarcity of estimates of genetic parameters for the breed, the maintenance and expansion of datasets suitable for this purpose should receive high priority.

Reproduction traits in the Boer goat doe

The aim of this review is to give insight into the reproduction potential of the Boer goat doe. Assessment of the reproduction traits in the Boer goat doe demonstrates a mean body weight at puberty of between 30.6 and 27.5kg, depending on the dietary energy level. Kids weaned during the natural breeding season (April/May) exhibit oestrus or puberty earlier than those weaned outside the natural breeding season. The mean age at the onset of puberty in the Boer goat doe is 191.1 and 157.2 days for kids born in August (late winter) and January (mid-summer). Although periods of complete anoestrus was not observed, the peak of sexual activity occurred during autumn and the period of lowest sexual activity from late spring to mid-summer. The duration of the oestrous cycle was recorded as being 20.7+/-0.7 days, with the mean duration of the oestrous period being 37.4+/-8.6h and the position of the LH peak (indicative of ovulation) being 8.0+/-1.5h following the onset of oestrus. The time of ovulation was recorded as occurring 36.8h after the onset of oestrus, with a mean ovulation rate of 1.72+/-0.9 ovulations per doe. The mean gestation period is quoted as being 148.2+/-3.7 days, with multiple births having no significant effect on gestation length. Involution of the Boer goat uterus is macroscopically complete by day 28 post-partum with the duration of the post-partum anoestrous period in the Boer goat being 55.5+/-24.9 days. The mean interval from partus to conception recorded, was 62.0+/-20.2 days. To optimise the reproductive efficiency in the Boer goat doe, it is essential that its reproductive potential be known and exploited.

Status of Dorper sheep as hosts of ectoparasites

Seventeen ixodid tick species or subspecies have been collected from Dorper sheep in South Africa. The diseases transmitted or the conditions caused by these ticks in sheep are discussed. Although Dorper sheep may be infested with the scab mite, Psoroptes ovis, this does not seem to cause production losses. These sheep may, however, serve as a source of mite infestation for woolled sheep. The majority of Dorper sheep are infested with the larvae of the nasal bot fly, Oestrus ovis, they may also be subject to myiasis caused by the larvae of two calliphorid flies. In certain regions of the country Dorper sheep are prone to serious fly worry by female Simulium chutteri. Although Dorper sheep may be infested by various louse species these do not seem to reach large numbers or cause production losses.

Bone disorders in the dog: a review of modern genetic strategies to find the underlying causes

In man, the genetic defects of more than 600 inherited diseases, of which at least 150 skeletal diseases, have been identified as is the chromosomal location for approximately 7000 genes. This rapid progress has been made possible by the generation of a genetical and physical map of the human genome. There is no reason to believe that for the dog not a similar development may occur. This review is therefore focussed on the use of novel tools now available for comparative molecular genetic studies of skeletal dysplasias in the dog. Because the genomes of mammals at the subchromosomal level are very well conserved, likely candidate disease genes known from other species might be considered. In this review, formation of the bones and the most important canine disorders of the skeleton influencing locomotion will be discussed first. The canine disorders discussed are canine hip dysplasia, the three different forms of elbow dysplasia (fragmented coronoid process, ununited anconeal process, osteochondrosis dissecans and incongruency) and dwarfism. Where possible a link is made with similar diseases in man or mouse. Then, the molecular biological tools available to analyse the genetic defect will be reviewed and some examples discussed.

Association between milk production, somatic cell count and bacterial dermatoses in three dairy cattle herds

OBJECTIVE

To determine the correlations between three bacterial dermatoses in cattle, milk production and bulk-milk somatic cell count (BMSCC).

DESIGN

Field observations in three dairy cattle herds.

METHODS

Milk production, BMSCC, fertility and all herd diseases were recorded by computerised dairy management systems. Each herd was visited twice weekly and the clinical signs, course of diseases and morbidity and culling rates were noted. Bulk-tank milk was sampled twice monthly and analysed for somatic cell count. Bacteriological and histological examinations were carried out from samples collected from affected animals in the respective herds.

RESULTS

The acute exudative form of dermatophilosis was diagnosed only in first-calving cows. The morbidity rate was 53% and the culling rate was 16% of the affected animals. The BMSCC increased by a factor of 2.4 times, and there was an average loss of milk production of 30%/cow/day in affected animals. Ulcerative lymphangitis was diagnosed in first-calving cows (22%) and older cows (15%). The culling rate was 28%. The BMSCC increased by a factor of 17.3 times, and the average loss of milk production was 5.5%/affected animal/day. Papillomatous digital dermatitis (PDD) was diagnosed in first-calving cows (25%) and in older cows (18%). The culling rate was 8%. The BMSCC increased by a factor of two times, and the average loss of milk production was 1.7%/affected animal/day.

CONCLUSIONS

The correlations between three skin diseases (ulcerative lymphangitis, dermatophilosis, papillomatous digital dermatitis), milk production and BMSCC have been found to be unfavourable.

Mammalian microsporidiosis

The phylum Microspora contains a diverse group of single-celled, obligate intracellular protozoa sharing a unique organelle, the polar filament, and parasitizing a wide variety of invertebrate and vertebrate animals, including insects, fish, birds, and mammals. Encephalitozoon cuniculi is the classic microsporidial parasite of mammals, and encephalitozoonosis in rabbits and rodents has been and continues to be recognized as a confounding variable in animal-based biomedical research. Although contemporary research colonies are screened for infection with this parasite, E. cuniculi remains a cause of morbidity and mortality in pet and conventionally raised rabbits. In addition, E. cuniculi is a potential pathogen of immature domestic dogs and farm-raised foxes. The recent discovery and identification of Encephalitozoon intestinalis, Encephalitozoon hellem, and Enterocytozoon bieneusi, in addition to E. cuniculi, as opportunistic pathogens of humans have renewed interest in the Microspora. Veterinary pathologists, trained in the comparative anatomy of multiple animal species and infectious disease processes, are in a unique position to contribute to the diagnosis and knowledge of the pathogenesis of these parasitic diseases. This review article covers the life cycle, ultrastructure, and biology of mammalian microsporaidia and the clinical disease and lesions seen in laboratory and domestic animals, particularly as they relate to Encephalitozoon species. Human microsporidial disease and animal models of human infection are also addressed. Often thought of as rabbit pathogens of historical importance, E. cuniculi and the related mammalian microsporidia are emerging as significant opportunistic pathogens of immunocompromised individuals.

VP7 and VP4 genotyping of human group A rotavirus in Buenos Aires, Argentina

Specific and sensitive tests for the detection and typing of group A rotavirus strains are needed for a more comprehensive knowledge of the epidemiology of rotaviral infection. In this study 500 stool specimens taken from 1996 to 1998 from children with acute diarrhea in Buenos Aires were examined. Group A rotavirus was unequivocally demonstrated in 62% of the samples tested by enzyme-linked immunosorbent assay (ELISA) for detection of VP6 antigen, polyacrylamide gel electrophoresis of double-stranded RNA, and reverse transcription-PCR (RT-PCR) for amplification of the VP7:G (1, 062 bp) and VP4:P (876 bp) genes. Only five positive specimens were found by RT-PCR but not by ELISA. G and P typing was carried out by nested amplification of variable sequences of the VP7 and the VP4 genes with six G- and five P-type-specific primers (multiplex PCR). Results obtained by this method showed the prevalence of the following G and P types: G1, 39%; G2, 43%; G4, 4%; P[8], 16%; P[4], 71%. Unexpectedly, the G-P type combination most frequently found was G2P[4] (43%) rather than G1P[8] (12%), which is the most commonly found worldwide. Unusual strains of the type G1P[4] accounted for 14% of the total, while mixed infections with more than one type were found in 10% of the samples. Detection of fecal rotavirus-specific immunoglobulin M (IgM) and IgA antibodies in consecutive samples of two patients taken at daily intervals demonstrated that high levels of IgM and IgA antibodies were detected on day 1 after the onset of disease and that the samples remained positive for about 10 days, after which virus shedding was no longer observed. Multiplex PCR offers a sensitive and specific alternative to determine the prevalence of group A rotavirus G and P types and to identify the emergence of uncommon strains, whereas detection of fecal IgM and IgA antibodies represents a useful supplement to virus detection for the diagnosis of current or recently acquired infections.

Culicoides biting midges: their role as arbovirus vectors

Culicoides biting midges are among the most abundant of haematophagous insects, and occur throughout most of the inhabited world. Across this broad range they transmit a great number of assorted pathogens of human, and domestic and wild animals, but it is as vectors of arboviruses, and particularly arboviruses of domestic livestock, that they achieve their prime importance. To date, more than 50 such viruses have been isolated from Culicoides spp. and some of these cause diseases of such international significance that they have been allocated Office International des Epizooties (OIE) List A status. Culicoides are world players in the epidemiology of many important arboviral diseases. In this context this paper deals with those aspects of midge biology facilitating disease transmission, describes the factors controlling insect-virus interactions at the individual insect and population level, and illustrates the far-reaching effects that certain components of climate have upon the midges and, hence, transmission potential.

Dermoid sinus at the lumbosacral junction in an English springer spaniel

A dermoid sinus was identified in a springer spaniel that presented with hindlimb neurological deficits. The sinus was continuous with the dura mater at the level of the lumbosacral junction. The presence of hair and debris adjacent to neural tissue had elicited a myelitis. A dorsal laminectomy was required to allow complete surgical resection of the sinus. The dog's neurological status improved after treatment and this improvement was maintained over a five-month follow-up period.

Encephalopathy with idiopathic hyperammonaemia and Alzheimer type II astrocytes in equidae

In 3 mature female horses of varying breeds, episodes of colic and depression for 14 days preceded an encephalopathic disorder with maniacal behaviour, anxiety, profuse sweating and, in one case, terminal opisthotonus. Blood ammonia levels were elevated approximately 10-fold. At necropsy, there were gastrointestinal serosal and mesenteric haemorrhages. Histologically, all 3 cases revealed diffuse Alzheimer type II astrocytes in the cerebral grey matter. Alzheimer type II astrocytes were glial fibrillary acidic protein (GFAP) negative or only weakly positive, weakly S-100 positive, and vimentin negative. In the absence of primary hepatic and/or renal lesions, an increase in intestinal ammonia absorption due to ileus or increased ammonia production by colonic bacteria is hypothesised.

Human microsporidial infection and possible animal sources

Sources of human microsporidial infection remain speculative, but possible animal reservoirs are emerging. Of the common human microsporidial infections, Enterocytozoon bieneusi has now been identified in non-human primates, pigs, dogs and a cat; Encephalitozoon intestinalis in dogs, pigs, cows, goats and donkeys and Encephalitozoon hellem in budgerigars and parrots. Evidence of species heterogeneity is also emerging suggesting that some animal isolates may be distinctive. Further molecular epidemiological studies need to be undertaken to clarify which animal genotypes can also infect humans. Some of the less common microsporidial infections found in humans, such as those involving Pleistophora-like species, may be the result of infrequent accidental exposure (for example, inadequately cooked infected fish muscle) and establishment, particularly if the individual is severely immunocompromised.

Cryptosporidia and microsporidia--waterborne diseases in the immunocompromised host

Cryptosporidia and microsporidia are emerging parasitic pathogens in immunocompetent and immunocompromised individuals. Cryptosporidium infects several wild and domestic animals that excrete oocysts into the environment and contaminated water represents the major source of infection for humans. Waterborne transmission of Cryptosporidium is a major risk for humans and appropriate measures have to be taken to protect immunocompetent and immunocompromised individuals to become infected. For microsporidia, the sources and ways of transmission are not well documented. Although several animal hosts have been identified recently, the relevant reservoirs of human microsporidia are still unknown. Also, the routes of spreading are unknown. Is microsporidiosis a zoonotic disease that will be transmitted through close contact with infected animals or is contaminated surface water responsible for transmission and represents a relevant reservoir? This review is designed to give information on these two emerging intestinal parasites in a format that will be useful to clinical microbiologists, physicians interested in infectious diseases, and public health personnel.

Propofol anesthesia

Although questions may still remain regarding the use of this unique sedative-hypnotic drug with anesthetic properties in high-risk patients, our studies have provided cardiopulmonary and neurological evidence of the efficacy and safety of propofol when used as an anesthetic under normal and selected impaired conditions in the dog. 1. Propofol can be safely and effectively used for the induction and maintenance of anesthesia in normal healthy dogs. Propofol is also a reliable and safe anesthetic agent when used during induced cardiovascular and pulmonary-impaired conditions without surgery. The propofol requirements to induce the safe and prompt induction of anesthesia prior to inhalant anesthesia with and without surgery have been determined. 2. The favorable recovery profile associated with propofol offers advantages over traditional anesthetics in clinical situations in which rapid recovery is important. Also, propofol compatibility with a large variety of preanesthetics may increase its use as a safe and reliable i.v. anesthetic for the induction and maintenance of general anesthesia and sedation in small animal veterinary practice. Although propofol has proven to be a valuable adjuvant during short ambulatory procedures, its use for the maintenance of general anesthesia has been questioned for surgery lasting more than 1 hour because of increased cost and marginal differences in recovery times compared with those of standard inhalant or balanced anesthetic techniques. When propofol is used for the maintenance of anesthesia in combination with a sedative/analgesic, the quality of anesthesia is improved as well as the ease with which the practitioner can titrate propofol; therefore, practitioners are able to use i.v. anesthetic techniques more effectively in their clinical practices. 3. Propofol can induce significant depression of respiratory function, characterized by a reduction in the rate of respiration. Potent alpha 2 sedative/analgesics (e.g., xylazine, medetomidine) or opioids (e.g., oxymorphone, butorphanol) increase the probability of respiratory depression during anesthesia. Appropriate consideration of dose reduction and speed of administration of propofol reduces the degree of depression. Cardiovascular changes induced by propofol administration consist of a slight decrease in arterial blood pressures (systolic, mean, diastolic) without a compensatory increase in heart rate. Selective premedicants markedly modify this characteristic response. 4. When coupled with subjective responses to painful stimuli, EEG responses during propofol anesthesia provide clear evidence that satisfactory anesthesia has been achieved in experimental dogs. When propofol is used as the only anesthetic agent, a higher dose is required to induce an equipotent level of CNS depression compared with the situation when dogs are premedicated. 5. The propofol induction dose requirement should be appropriately decreased by 20% to 80% when propofol is administered in combination with sedative or analgesic agents as part of a balanced technique as well as in elderly and debilitated patients. As a general recommendation, the dose of propofol should always be carefully titrated against the needs and responses of the individual patient, as there is considerable variability in anesthetic requirements among patients. Because propofol does not have marked analgesic effects and its metabolism is rapid, the use of local anesthetics, nonsteroidal anti-inflammatory agents, and opioids to provide postoperative analgesia improves the quality of recovery after propofol anesthesia. 6. The cardiovascular depressant effects of propofol are well tolerated in healthy animals, but these effects may be more problematic in high-risk patients with intrinsic cardiac disease as well as in those with systemic disease. In hypovolemic patients and those with limited cardiac reserve, even small induction doses of propofol (0.75-1.5 mg/kg i.v.) can produce profound hypotens

Molecular techniques for detection, species differentiation, and phylogenetic analysis of microsporidia

Microsporidia are obligate intracellular protozoan parasites that infect a broad range of vertebrates and invertebrates. These parasites are now recognized as one of the most common pathogens in human immunodeficiency virus-infected patients. For most patients with infectious diseases, microbiological isolation and identification techniques offer the most rapid and specific determination of the etiologic agent. This is not a suitable procedure for microsporidia, which are obligate intracellular parasites requiring cell culture systems for growth. Therefore, the diagnosis of microsporidiosis currently depends on morphological demonstration of the organisms themselves. Although the diagnosis of microsporidiosis and identification of microsporidia by light microscopy have greatly improved during the last few years, species differentiation by these techniques is usually impossible and transmission electron microscopy may be necessary. Immunfluorescent-staining techniques have been developed for species differentiation of microsporidia, but the antibodies used in these procedures are available only at research laboratories at present. During the last 10 years, the detection of infectious disease agents has begun to include the use of nucleic acid-based technologies. Diagnosis of infection caused by parasitic organisms is the last field of clinical microbiology to incorporate these techniques and molecular techniques (e.g., PCR and hybridization assays) have recently been developed for the detection, species differentiation, and phylogenetic analysis of microsporidia. In this paper we review human microsporidial infections and describe and discuss these newly developed molecular techniques.

The first finding of antibodies to Encephalitozoon cuniculi in cows in Slovakia

The presence of antibodies against Encephalitozoon cuniculi in cows was observed by the method of indirect immunofluorescence (IFAT). The animals reacting at the titre 1:64 and more were considered positive. Of the total number of 55 sera examined, 20 were positive at the titre 1:64, from which four were positive at the titre 1:256 also. Our results indicate that it is very important to carry out screening examinations in large-scale breeding of cattle due to the persistent high percentage of bovine abortions and disorders in the reproductive cycle of unknown etiology.

Occurrence and diversity of coccidia in indigenous, Saanen and crossbred goats in South Africa

Occurrence and diversity of Eimeria species in two groups of indigenous South African goats kept under traditional management systems, as well as in a mixed herd of Saanen, indigenous and crossbred goats kept under an intensive management system were examined. Infection rates ranged from 88.7 to 100% in the various groups. Mean OPG of immature goats (< 1 year old) exceeded that of adult goats at all three sites. There was no consistent difference between adult OPG counts at the three sites. Under the intensive system, adult crossbred goats had significantly higher OPG counts than adult Saanen or indigenous goats. Overall, OPG counts of immature goats were significantly higher during the dry season (winter) than during the wet season (summer). Ten Eimeria species were identified, Eimeria arloingi being the most prevalent species at all three sites, followed by Eimeria hirci. Up to seven Eimeria species were recovered from individual specimens.

Persistence of the activity of topical ivermectin against biting lice (Bovicola bovis)

To assess the persistence of the activity of topical ivermectin against a natural challenge with biting lice (Bovicola bovis), 90 mixed-breed cattle that had been treated to remove lice, were blocked by bodyweight within sex and randomly allocated to three treatments: untreated control, doramectin at 200 micrograms/kg by subcutaneous injection, and ivermectin at 500 micrograms/kg by topical application. Forty-five pens were blocked into three groups of 15, and the blocks of pens were randomly allocated to three 14-day challenge periods starting 21, 28 and 35 days after treatment. There were five pens per treatment for each challenge period, and one B bovis-infested donor calf was introduced into each pen containing two principal calves at the start of the challenge period for that block of pens. The calves were examined thoroughly for B bovis seven, 14 and 21 days after the introduction of the donors. There were no significant differences between the control and doramectin groups for the numbers of animals infested, or the geometric mean louse counts at the final examination for any of the challenge periods. At the final examination for each challenge period, the louse counts of the cattle treated with topical ivermectin were all zero, and significantly (P < 0.05) fewer cattle treated with topical ivermectin were infested than either the controls or cattle treated with doramectin.

Laminitis in young dairy calves fed a high starch diet and with a history of bovine viral diarrhoea virus infection

Six of the 33 calves born in a Swedish dairy herd during a period of four months developed laminitis when they were eight to 12 weeks old. The clinical signs included difficulty in rising, a stiff gait, overgrown claws and haemorrhages in the sole horn. Samples of blood were taken from four of the calves when they had shown signs of laminitis for two to seven weeks; the serum concentrations of calcium, phosphorus and vitamin D3, the activities of aspartate aminotransferase and glutathione peroxidase, and the patterns of serum proteins were within their normal ranges. The feet of the same four calves were examined after slaughter; the third phalanx of each calf was rotated and its distal end osteolytic. Histologically there was separation and degeneration of the squamous cells of the white line, and thromboses and vasculitis in the fine vessels of the corium. Four of the six affected calves were persistently infected with bovine viral diarrhoea virus and one had antibodies against the virus. From six weeks of age the calves had been fed rye wheat, a hybrid seed rich in starch, and this may have contributed to the outbreak of laminitis.

Encephalitozoon hellem in budgerigars (Melopsittacus undulatus)

Microsporidiosis with concurrent megabacteriosis in budgerigar (Melopsittacus undulatus) chicks contributed to significant economic floss in a commercial pet bird aviary in Mississippi. Three budgerigar chicks, 1-2 weeks old, from the aviary were necropsied. Microscopic lesions in the chicks consisted of heavy infection of enterocytes with microsporidia (2/3; autolysis precluded critical evaluation of the intestine of chick No. 2), multifocal hepatic necrosis and inflammation with intralesional microsporidia (1/3), spherical clusters of microsporidia in the hepatic sinusoids in the absence of inflammation (1/3), and gastric megabacteriosis (3/3). The ultrastructure of the microsporidian spores was consistent with an Encephalitozoon species. The polymerase chain reaction and Southern blot analysis were used to identify the microsporidian as Encephalitozoon hellem, an organism that has only been identified in humans. Encephalitozoon hellem causes keratoconjunctivitis and respiratory infections in humans with acquired immunodeficiency syndrome. This report presents the first confirmed case of microsporidiosis in budgerigars. The finding of E. hellem in pet birds may be important in elucidating the epidemiology of human infections with this organism.