Genetic resistance to experimental infection with Mycobacterium bovis in red deer (Cervus elaphus).

Tuberculosis (Tb) caused by Mycobacterium bovis is a worldwide threat to livestock and humans. One control strategy is to breed livestock that are more resistant to Mycobacterium bovis. In a 3-year heritability study 6 farmed red deer stags were selected from 39 on the basis of their differing responses to experimental challenge via the tonsillar sac with approximately 500 CFU of M. bovis. Two stags remained uninfected, two were moderately affected, and two developed serious spreading Tb. Seventy offspring, bred from these six stags by artificial insemination using stored semen, were similarly challenged with M. bovis. The offspring showed patterns of response to M. bovis challenge similar to those of their sires, providing evidence for a strong genetic basis to resistance to Tb, with an estimated heritability of 0.48 (standard error, 0.096; P < 0. 01). This is the first time the heritability of Tb resistance in domestic livestock has been measured. The breeding of selection lines of resistant and susceptible deer will provide an ideal model to study the mechanisms of Tb resistance in a ruminant and could provide an additional strategy for reducing the number and severity of outbreaks of Tb in farmed deer herds. Laboratory studies to identify genetic and immunological markers for resistance to Tb are under way. Preliminary studies showed no associations between NRAMP or DRB genes and resistance to Tb in deer. Patterns of immune responses seen in resistant animals suggest that both innate and acquired pathways of immunity are necessary to produce the resistant phenotype.

The efficacy of a pour-on formulation of moxidectin in young red and wapiti-hybrid deer.

AIMS: To measure the efficacy of a pour-on formulation of moxidectin against lungworm and abomasal parasites in weaner wapiti x red deer and to compare this with its efficacy in weaner red deer. METHODS: Six red and six wapiti hybrid deer, naturally infected with lungworm and gastro-intestinal parasites, were treated with pour-on moxidectin at 500 microg/kg body weight and slaughtered 14 or 16 days later, along with six red and six wapiti hybrid untreated control deer. Total worm counts were performed on the lungs, abomasum and abomasal digest of each deer. RESULTS: The efficacy of moxidectin pour-on was 100% against adult and immature lungworms (Dictyocaulus viviparus) in red deer, and 100% and 99.7% effective against adult and immature lungworm in wapiti hybrid deer. The efficacy of moxidectin pour-on was 100, 100, 99.9 and 99.9% respectively against adult, fifth stage, late fourth stage and early fourth stage larvae of Ostertagia-type nematodes (assumed to be Ostertagia, Spiculopteragia, Skrjabinagia and Apteragia spp.) in both red and wapiti hybrid deer. CONCLUSIONS: The pour-on formulation of moxidectin, at 500 microg/kg body weight, is highly effective against mature and immature lungworms and abomasal nematodes in wapiti hybrid deer and equally effective in red deer.

The prevalence of bovine tuberculosis (Mycobacterium bovis) infections in feral populations of cats (Felis catus), ferrets (Mustela furo) and stoats (Mustela erminea) in Otago and Southland, New Zealand.

Twenty-one properties in the Otago region of the South Island of New Zealand were surveyed for the presence of gross lesions due to Mycobacterium bovis infection in feral cats (Felis catus), ferrets (Mustela furo) and stoats (Mustela erminea) during 1993 and 1994. In total, 1293 cats, ferrets, stoats and weasels (Mustela nivalis) were examined for the presence of tuberculous lesions. The properties surveyed were selected according to the history and incidence of bovine tuberculosis infection in their cattle herds. Sixteen infected cattle properties were trapped in areas of Otago that were endemic for bovine tuberculosis and five properties were trapped in non-endemic areas that were considered to be free from tuberculosis infection in the cattle. No tuberculous cats, ferrets, stoats or weasels were found in non-endemic areas, and prevalence rates in the endemic areas were 0.9% for cats (n=215, 0.12

The distribution of gross lesions of tuberculosis caused by Mycobacterium bovis in feral ferrets (Mustela furo) from Otago, New Zealand.

The distribution of gross lesions of Mycobacterium bovis was examined in 94 tuberculous feral ferrets (Mustela furo) collected from 1992 to 1995 from areas of Otago endemic for bovine tuberculosis. Overall, 56.4% of tuberculous ferrets had single-site lesions, 24.5% had multiple infections and 19.1% had generalised infections. The mesenteric lymph node was the most common site of infection (34.5% of all lesions), with the retropharyngeal (17%) and the prescapular lymph nodes (16.4%) also frequently infected. Only 2.9% of lesions involved the respiratory tract. Of single-site lesions, 60.4% were in the mesenteric lymph node. The high proportion of lesions in the alimentary tract suggests that the ingestion of infectious material, possibly carrion or prey, is an important source of infection. Peripheral lymph nodes contributed to 24.5% of all infections, suggesting that within species transmission by social contact such as fighting and mating also occurs. Open and respiratory lesions were found in 11.7% of tuberculous ferrets, which suggests that ferrets are potentially infectious and therefore may be involved in the transmission of bovine tuberculosis to domestic stock and other mammals. The distribution of gross M. bovis lesions in ferrets is compared to those observed in possums (Trichosurus vulpecula) and badgers (Meles meles).

Histogenesis of antlerogenic tissues cultivated in diffusion chambers in vivo in red deer (Cervus elaphus).

In a previous study we showed that formation of deer pedicle and first antler proceeded through four ossification pattern change stages: intramembranous, transition, pedicle endochondral, and antler endochondral. In the present study antlerogenic tissues (antlerogenic periosteum, apical periosteum/perichondrium, and apical perichondrial of pedicle and antler) taken from four developmental stages were cultivated in diffusion chambers in vivo as autografts for 42-68 days. The results showed that all the cultivated tissues without exception formed trabecular bone de novo, irrespective of whether they were forming osseous, osseocartilaginous, or cartilaginous tissue at the time of initial implant surgery; in two cases in the apical perichondria from antler group, avascularized cartilage also formed. Therefore, the antlerogenic cells, like the progenitor cells of somatic secondary type cartilage, have a tendency to differentiate into osteoblasts and then form trabecular bone. Consequently, the differentiation pathway whereby antlerogenic cells change from forming osteoblasts to forming chondroblasts during pedicle formation is caused by extrinsic factors. Both oxygen tension and mechanical pressure are postulated to be the factors that cause this alteration of the differentiation pathway.

Effects of unilateral cranial sympathectomy either alone or with sensory nerve sectioning on pedicle growth in red deer (Cervus elaphus).

In a previous study (Li et al. [1993], J. Exp. Zool., 267:188-197) sensory nerve sectioning had no effect on the timing of pedicle growth. The aim of the present study was to determine whether sensory nerve sectioning in conjunction with sympathectomy would influence pedicle growth. Twelve intact male red deer calves were allocated to treatment before any pedicle growth as follows: 1) unilateral sensory nerve removal (USX, n = 5), 2) unilateral superior cervical ganglionectomy (SGX, n = 4), or 3) both USX and SGX (SG/USX, n = 3). The calves were observed weekly. In all cases the untreated side was the control. Pedicle initiation was measured with a pedicle detector and after initiation, growth was measured with a ruler. When the treated pedicles reached a length of 60 mm the calves were killed and tissues from the pedicle were examined immunohistochemically for nerves. No large bundles of nerves were observed in the treated pedicle although a few fine fibres were present. All calves grew pedicles. There were no significant differences in the timing of pedicle initiation either within treatment or between treatments. All denervated pedicles grew faster than controls and were consequently higher at examination. The fact that pedicle growth took place despite reduced innervation indicates that a continuous neural connection is not a pre-requisite for normal pedicle growth.

A difference in abomasal pH between Canadian wapiti affected with chronic illthrift and unaffected deer.

The pH of abomasal fluid from five purebred Canadian wapiti which were diagnosed with chronic illthrift ("fading") was found to be elevated compared to ten clinically normal red and hybrid (wapiti x red) deer. The average abomasal pH of the affected elk was 6.3, compared to 2.5 for the unaffected red and hybrid deer.

Ultrastructural characteristics of Babesia odocoilei in vitro.

Babesia odocoilei continuously cultured in white-tailed deer (Odocoileus virginianus) erythrocytes was examined by transmission and scanning electron microscopy. Merozoites, trophozoites, intermediate-stage forms, and dividing forms were observed. Merozoites possessed a single nucleus, inner membrane complex, rhoptries, free ribosomes, rough endoplasmic reticulum, and single membrane-bound vesicles. Trophozoites lacked an inner membrane complex and rhoptries. Intermediate stages were characterized by distinct segments of inner membrane complex. Dividing forms ranged from cells with an elongated nucleus to mature daughter cells joined by a ringlike structure. Babesia odocoilei was characterized by its close proximity to the erythrocyte membrane, membranous structures resembling feeding organelles, and reproduction via a method resembling budding sensu stricto.

The isolation and partial characterization of a Babesia sp. from desert bighorn sheep (Ovis canadensis nelsoni).

A novel Babesia parasite of desert bighorn sheep was isolated. Its taxonomic description, host range, pathogenicity and antigenic relatedness were investigated. The parasite was infective for black-tailed and white-tailed deer, but with host-specific differences compared to that of bighorn sheep. A splenectomized calf and domestic sheep were refractory to infection. A comparative immunofluorescence assay detected antigens cross-reactive with Babesia odocoilei, B. divergens, B. equi and B. caballi, but not with B. bovis or B. bigemina. Babesia odocoilei was also infective for bighorn sheep, allowing comparison by a cross-challenge experiment, the results of which supported the conclusion that this parasite was not B. odocoilei. However, the bighorn sheep Babesia cannot currently be distinguished from B. capreoli described from roe deer in northern Germany. Data indicate that, while this parasite may not present a problem for domestic animals, it may cause disease in bighorn sheep and deer populations.

In vitro growth of Babesia bovis in white-tailed deer (Odocoileus virginianus) erythrocytes.

Babesia bovis cultured in bovine erythrocytes was passaged into white-tailed deer (Odocoileus virginianus) erythrocytes and medium containing either white-tailed deer serum or bovine serum. Deer erythrocytes supported the growth of the parasite only in the presence of bovine serum. Cryopreserved cultures were recovered successfully in white-tailed deer erythrocytes. By light and electron microscopy, B. bovis structure appeared similar in host cells of either species.

Carrier erythrocytes from white-tailed deer: morphology, osmotic fragility and survival of circulating sickled erythrocytes.

Carrier erythrocytes are used to disseminate drugs in the circulatory system of animals. Carrier erythrocytes prepared from white-tailed deer (Odocoileus virginianus) do not circulate well in vivo. Although carrier cells were prepared from sickle and non-sickle cells with no apparent differences, their 24-hour survival was only 10 per cent. Osmotic fragility of carrier cells was increased over that of normal deer erythrocytes. Unlike erythrocytes from other ruminants, deer carrier erythrocytes are extremely fragile. Scanning electron micrographs of deer erythrocytes (sickle or non-sickle) in different stages of carrier cell preparation revealed no morphological differences. These data suggest that carrier cells from deer would not be amenable for use in long-term dissemination of drugs.

Monthly incidence of Theileria cervi and seroconversion to Babesia odocoilei in white-tailed deer (Odocoileus virginianus) in Texas.

Monthly monitoring of fawns collected from an area in Texas endemic for Theileria cervi and Babesia odocoilei showed that transmission of T. cervi occurred during July and August, a time period consistent with the occurrence of Amblyomma americanum. Seroconversion to B. odocoilei occurred during October to December and possibly continued through January and February. The time of seroconversion was more suggestive of transmission of B. odocoilei by Ixodes scapularis than by Amblyomma americanum.

Comparative studies of Babesia spp. from white-tailed and sika deer.

Babesia odocoilei from white-tailed deer (Odocoileus virginianus) in Texas (USA) and B. capreoli isolated from sika deer (Cervus nippon) in Ireland were compared morphologically and antigenically. Babesia odocoilei and B. capreoli paired pyriforms resembled each other closely when in sika deer, but B. odocoilei pyriforms in white-tailed deer were slightly different. Babesia odocoilei in white-tailed deer also differed from B. odocoilei and B. capreoli in sika deer in the frequency of its developmental forms. Indirect immunofluorescence antibody test titres showed that there was some antigen cross-reactivity, but not as much as between B. capreoli and the bovine parasite, B. divergens. The Babesia spp. from deer that we studied appear to be distinct but related species. The low infectivity of B. odocoilei for a splenectomised sika deer suggests that sika deer in North America are probably not very susceptible to this parasite in the wild.

Transmission of Babesia odocoilei in white-tailed deer (Odocoileus virginianus) by Ixodes scapularis (Acari: Ixodidae).

Laboratory reared Ixodes scapularis proved to be an efficient vector of Babesia odocoilei Emerson and Wright between white-tailed deer (Odocoileus virginianus). Transtadial survival of the babesia occurred between nymph and adult stages of the tick, and the adult stage transmitted the babesia.

Serological prevalence and isolation of Babesia odocoilei among white-tailed deer (Odocoileus virginianus) in Texas and Oklahoma.

Serum samples collected from 581 white-tailed deer (Odocoileus virginianus) from Texas and from 124 white-tailed deer from Oklahoma were tested by the indirect fluorescent antibody technique against Babesia odocoilei. Prevalence of seropositive reactors varied from site to site in both states. Prevalence rates were statistically ranked as high, intermediate or low. Deer less than 12-mo-old had a significantly lower prevalence than all other age classes.

Scrotal cestodiasis in a dog.

Scrotal cestodiasis was diagnosed from a surgical biopsy specimen from an 8-year-old Miniature Poodle. Peritoneal cestodiasis with secondary scrotal cestodiasis was suspected and could be explained by migration of the parasite along the vaginal tunics. Subsequent necropsy confirmed severe peritoneal cestodiasis due to Mesocestoides sp. It appears that scrotal cestodiasis may be an early indicator of peritoneal cestodiasis in male dogs and diagnostic pathologists and clinicians should be aware of this condition.

In vitro cultivation of a Babesia isolated from a white-tailed deer (Odocoileus virginianus).

Pyriforms and ring forms of Babesia odocoilei were detected in thin blood smears obtained from a white-tailed deer killed by a hunter in Anderson County, Texas. Erythrocytes from the deer were cultured and the parasites maintained through 8 serial subcultures during 1 mo. The parasite was successfully established in culture using Medium 199 supplemented with either 20% deer serum or 40% normal adult bovine serum. The highest parasitemia observed was 30% and more than 4 parasites per erythrocyte were often observed. Cultured B. odocoilei remained infective for a susceptible white-tailed deer.