High winter loads of Oestrid larvae and Elaphostrongylus rangiferi are associated with emaciation in wild reindeer calves.

The Oestrid flies Cephemyia trompe and Hypoderma tarandi and the nematode Elaphostrongylus rangiferi are important parasites of Rangifer spp. The larvae of Oestrid flies develop in the throat (C. trompe) and skin (H. tarandi) of their host during winter while E. rangiferi develop in the CNS. Oestrid pupation, and development of E. rangiferi larvae from first- (L1) to infective third- stage in the environment during summer are highly temperature dependent. We investigated the possible negative effects of these parasites on the winter body-condition of wild reindeer calves. Two year-classes (generations) of calf, born in a warm (2014) and cold (2015) summer respectively, were examined for changes in body condition between autumn and spring, in relation to the parasite load determined in the spring. The body condition in the autumn was assessed as carcass weight, while the body condition in the spring was assessed as carcass weight, supplemented by an evaluation of fat reserves in various bodily locations. Oestrids were counted directly whereas the E. rangiferi quantification was based on faecal counts of L1 larvae. The abundance of infections for Oestrids and E. rangiferi were significantly greater in the 2014 generation than in the 2015 generation. The mean carcass weight decreased between autumn and spring for the 2014 generation but increased in the 2015 generation. Emaciation in the spring was documented (fat reserve evaluation) in 42% and 7% of calves in the 2014 and 2015 cohorts, respectively. There was a significant correlation between high parasite load and the probability of emaciation. The mean summer temperature in 2014 was 2.6 °C higher than the mean for 2015, and 1.0 °C higher than the mean for the last 30-years. Our findings suggest that following a warm summer, high loads of Oestrids and E. rangiferi may cause emaciation and potentially deaths among the calves.

Mycoplasma conjunctivae-Associated Keratoconjunctivitis in Norwegian Muskox (Ovibos moschatus).

In late summer 2014, an outbreak of ocular disease occurred in the Norwegian muskox (Ovibos moschatus) population. Animals showed rings of pus around their eyes and one euthanized animal was diagnosed with acute keratoconjunctivitis. The DNA sequence analysis of eye-swab samples from this animal revealed a high abundance of Mycoplasma conjunctivae.

Elaphostrongylus and Dictyocaulus infections in Norwegian wild reindeer and red deer populations in relation to summer pasture altitude and climate.

Nematodes of the genera Elaphostrongylus and Dictyocaulus are associated with disease in semi-domesticated tundra reindeer and farmed red deer whereas less knowledge exists in the wild. Their first stage larvae (L1) develop to the infective third stage (L3) in the environment; Elaphostrongylus spp. within intermediate gastropod hosts and Dictyocaulus spp. as free-living larvae. Larval development of Elaphostrongylus is highly temperature dependent with a developmental minimum of 9-10 °C. Larval development of Dictyocaulus spp. may occur at low temperatures (5 °C) but the larvae are sensitive to desiccation. We examined the prevalence and intensity of Elaphostrongylus spp. and Dictyocaulus spp. infections in six wild reindeer and two wild red deer populations in relation to altitude, temperature and rainfall in their respective main summer pasture area over the 5 summers prior to sampling. The parasitological examination was based upon morphological identification of L1 in the faeces of hunted animals. Altitude was calculated from animal position data and temperature and precipitation by means of a nationwide gridded data set. Temperature decreased with increasing altitude, from 13.3 °C for the lowest located red deer population (300 m) to 6.1 °C for the highest located reindeer population (1400 m). No significant relationship between altitude and rainfall was identified. Elaphostrongylus spp. infection decreased in prevalence with increasing altitude, being identified in 89% of investigated samples from the lowest located population and in 3% of samples from the highest. The prevalence of Dictyocaulus spp. infection varied between 28 and 80% and no relationship with altitude was found. The intensity of Elaphostrongylus spp. infection was low in reindeer and moderate in red deer whereas the intensity of Dictyocaulus spp. infection was moderate in both species. Our results indicated that the climatic conditions in all areas studied were suitable for Dictyocaulus spp., whereas summer temperature was a restrictive factor for Elaphostrongylus sp. in reindeer.

First Detection of Chronic Wasting Disease in a Wild Red Deer (Cervus elaphus) in Europe.

Chronic wasting disease (CWD) is a fatal contagious prion disease naturally occurring in cervids in North America. In 2016, CWD was detected in wild reindeer (Rangifer tarandus) and moose (Alces alces) in Norway. Here, we report the first known naturally infected wild Norwegian red deer (Cervus elaphus).

Gammaherpesvirus (Type 1 Ruminant Rhadinovirus) in Muskox ( Ovibos moschatus) in Greenland.

The world's native distribution of muskox ( Ovibos moschatus) is restricted to Canada and Greenland, and a muskox-specific gammaherpesvirus has been described from Canadian populations. We analyzed spleen samples from the Kangerlussuaq muskox population in Greenland and identified muskox gammaherpes by PCR and sequencing.

Yew (Taxus) intoxication in free-ranging cervids.

Wild ruminants, including deer species (cervids) have incorrectly been regarded as refractory to yew (Taxus) intoxication. This assumption has been based upon anecdotal observations of individual deer browsing on yew over time without apparent adverse effect. A single case of yew intoxication was reported in a free-ranging Norwegian moose (Alces alces) in 2008. The current report describes five additional cases of yew toxicosis in moose, seven in roe deer (Capreolus capreolus) and two in reindeer (Rangifer tarandus tarandus), all in Norway. The animals were found dead during the winter, close to or within gardens containing yew plants showing signs of browsing. Gross findings included lung congestion and edema, thoracic and pericardial effusion, bilateral heart dilatation, epi- and endocardial hemorrhage, and enlarged (congested) spleen. Yew plant remnants were detected in the rumen of all animals with the exception of a single moose. Histology revealed multifocal acute myocardial degeneration and necrosis with hemorrhage in roe deer, but not in the two other species. A qualitative high performance liquid chromatography-ion trap mass spectrometry analysis was used to tentatively identify five major Taxus alkaloids (taxines) in crude yew extracts and in heart and liver samples from the moose cases. All five major taxines were detected with good signal/noise ratio in tissue samples from the four moose with visible ruminal yew content, whereas lower levels of taxines were detected in the moose without visible ruminal yew content. Possible differences in interspecies tolerance to taxines and role of individual protective adaptation are discussed.

Low Copper Levels Associated with Low Carcass Weight in Wild Red Deer ( Cervus elaphus ) in Norway.

Copper (Cu) deficiency is associated with several disease syndromes, including poor growth, in farmed red deer ( Cervus elaphus ), but little is known of the consequences of low Cu levels in free-ranging populations. Low hepatic Cu levels have been documented in several wild red deer populations along the west coast of Norway, with the lowest values found on the island of Hitra. We studied the relationship between liver Cu concentration and slaughter weight in 63 red deer calves and 69 yearlings shot on Hitra during the autumn hunting season of 2009. Less than half of each age class had adequate Cu levels (>20 µg/g dry weight) and 14% of the calves and 28% of the yearlings had levels indicating deficiency (<13 µg/g). For yearlings, but not calves, there was a significant increase in slaughter weight with increasing hepatic Cu level. The differences between yearlings and calves could be linked to differences in physiologic Cu status of the two age classes, in that red deer calves are born with much higher levels of hepatic Cu than are their mothers. Our data demonstrate an association between low levels of Cu and reduced growth rate in a free-ranging cervid population.

Resurrection and redescription of Varestrongylus alces (Nematoda: Protostrongylidae), a lungworm of the Eurasian moose (Alces alces), with report on associated pathology.

BACKGROUND: Varestrongylus alces, a lungworm in Eurasian moose from Europe has been considered a junior synonym of Varestrongylus capreoli, in European roe deer, due to a poorly detailed morphological description and the absence of a type-series. METHODS: Specimens used in the redescription were collected from lesions in the lungs of Eurasian moose, from Vestby, Norway. Specimens were described based on comparative morphology and integrated approaches. Molecular identification was based on PCR, cloning and sequencing of the ITS-2 region of the nuclear ribosomal DNA. Phylogenetic analysis compared V. alces ITS-2 sequences to these of other Varestrongylus species and other protostrongylids. RESULTS: Varestrongylus alces is resurrected for protostrongylid nematodes of Eurasian moose from Europe. Varestrongylus alces causes firm nodular lesions that are clearly differentiated from the adjacent lung tissue. Histologically, lesions are restricted to the parenchyma with adult, egg and larval parasites surrounded by multinucleated giant cells, macrophages, eosinophilic granulocytes, lymphocytes. The species is valid and distinct from others referred to Varestrongylus, and should be separated from V. capreoli. Morphologically, V. alces can be distinguished from other species by characters in the males that include a distally bifurcated gubernaculum, arched denticulate crura, spicules that are equal in length and relatively short, and a dorsal ray that is elongate and bifurcated. Females have a well-developed provagina, and are very similar to those of V. capreoli. Morphometrics of first-stage larvae largely overlap with those of other Varestrongylus. Sequences of the ITS-2 region strongly support mutual independence of V. alces, V. cf. capreoli, and the yet undescribed species of Varestrongylus from North American ungulates. These three taxa form a well-supported crown-clade as the putative sister of V. alpenae. The association of V. alces and Alces or its ancestors is discussed in light of host and parasite phylogeny and host historical biogeography. CONCLUSIONS: Varestrongylus alces is a valid species, and should be considered distinct from V. capreoli. Phylogenetic relationships among Varestrongylus spp. from Eurasia and North America are complex and consistent with faunal assembly involving recurrent events of geographic expansion, host switching and subsequent speciation.

Gastrointestinal parasites in an isolated Norwegian population of wild red deer (Cervus elaphus).

BACKGROUND: Thirteen red deer (Cervus elaphus), culled from the isolated population at the Mongstad Oil Refinery, Norway, were investigated for gastrointestinal helminths. These animals, enclosed by the refinery fence, do not have contact with other ruminants and have a high population density considering the available browsing area (1 km(2)) within the refinery site (3 km(2)). The population was estimated to be 110-130 at the time of culling. RESULTS: The helminth fauna among these sampled red deer was enumerated and species were identified based on morphology. Ostertagia leptospicularis/O. kolchida was detected in 83% [CI 55 - 95%], Spiculopteragia spiculoptera/S. mathevossiani in 92% [CI 65 - 99%] and Trichostrongylus axei in 42%, [CI 19 - 68%] of the abomasa examined. Characterisation of the intestinal parasite fauna revealed Capillaria bovis, Cooperia oncophora, Oesophagostomum venulosum, Trichuris globulosa and tapeworm fragments (presumed anoplocephalids) in seven individuals. Only one calf had an infection with more than one intestinal helminth (tapeworm fragment and Trichuris globulosa). The remaining six deer had single species intestinal infections. No significant age related trends were seen, with the exception of higher intensity of infection of T. axei in yearlings relative to other age classes. Assessment of abomasal parasite burden and body condition revealed no significant trends. In calves, statistically non-significant correlation was seen between increased parasite burden and decreased slaughter weight, whilst the opposite was seen in adults with the heaviest adults exhibiting the higher burdens. Given the small sample size the trends that were seen need further investigation. The parasite burden was aggregated with three adult red deer harbouring 75% of the total abomasal parasite count. CONCLUSION: This isolated population was parasitised by a reduced subset of gastrointestinal nematodes typical of this cervid across an extensive geographic range in Eurasia. The intensity and abundance of abomasal nematodes was higher in this isolated population than reported in similar studies of red deer populations across Europe.

Mycoplasma ovipneumoniae--a primary cause of severe pneumonia epizootics in the Norwegian Muskox (Ovibos moschatus) population.

The Norwegian muskox (Ovibos moschatus) population lives on the high mountain plateau of Dovre and originates from animals introduced from Greenland. In the late summers of 2006 and 2012, severe outbreaks of pneumonia with mortality rates of 25-30% occurred. During the 2012 epidemic high quality samples from culled sick animals were obtained for microbiological and pathological examinations. High throughput sequencing (pyrosequencing) of pneumonic lung tissue revealed high concentrations of Mycoplasma ovipneumoniae in all six animals examined by this method and Pasteurella multocida subsp. multocida in four animals, whereas no virus sequences could be identified. Mycoplasma ovipneumoniae and P. multocida multocida were also isolated by culture. Using real time PCR on lung swabs, M. ovipneumoniae was detected in all of the 19 pneumonic lungs examined. Gross pathological examination revealed heavy consolidations primarily in the cranial parts of the lungs and it also identified one case of otitis media. Histologically, lung lesions were characterized as acute to subacute mixed exudative and moderately proliferative bronchoalveolar pneumonia. Immunohistochemical (IHC) examination revealed high load of M. ovipneumoniae antigens within lung lesions, with particularly intensive staining in the neutrophils. Similar IHC finding were observed in archived lung tissue blocks from animals examined during the 2006 epidemic. An M. ovipneumoniae specific ELISA was applied on bio-banked muskox sera from stray muskoxen killed in the period 2004-2013 and sick muskoxen culled, as well as sera from wild reindeer (Rangifer tarandus tarandus) on Dovre and muskoxen from Greenland. Serology and mycoplasma culturing was also carried out on sheep that had been on pasture in the muskox area during the outbreak in 2012. Our findings indicated separate introductions of M. ovipneumoniae infection in 2006 and 2012 from infected co-grazing sheep. Salt licks shared by the two species were a possible route of transmitting infection.

Tularaemia in Norwegian dogs.

We describe tularaemia in a Norwegian dog caused by Francisella tularensis subspecies holarctica. A Hamilton Hound and his owner developed tulaeremia after hunting an infected mountain hare (Lepus timidus). The dog showed signs of lethargy, anorexia and fever during a period two to four days after hunting and thereafter fully recovered. Its antibody titers increased 32-fold from one to three weeks post exposure. Thereafter, the titer declined and leveled off at moderate positive values up to one year after exposure (end of study). This is believed to be the first case report of clinical F. tularensis subspecies holarctica infection in a European dog. In 2011, enormous numbers of Norway lemmings (Lemmus lemmus) occurred in Finnmark, the northernmost county of Norway and many dogs caught and swallowed lemmings. Some of these dogs developed non-specific signs of disease and the owners consulted a veterinary surgeon, who suspected tularaemia. In order to investigate this hypothesis, serum samples from 33 dogs were examined for antibodies to F. tularensis. The dogs were allocated into three groups: Dogs from Finnmark that became sick (Group 1) or remained healthy following contact with lemmings (Group 2), and healthy control dogs from Oslo without known contact with lemmings (Group 3). All the serum samples were analyzed with a tube agglutination assay. Among dogs exposed to lemmings, 10/11 and 3/12 were antibody positive in Group 1 and Group 2, respectively, whereas none of the control dogs (n=10) were positive for antibodies against F. tularensis. These results strongly indicate that the non-specific disease seen in the dogs in Finnmark was linked to F. tularensis infection acquired through contact with lemmings.

Ixodes ricinus infestation in free-ranging cervids in Norway--a study based upon ear examinations of hunted animals.

Prevalence, abundance and instar composition of Ixodes ricinus as found on one ear collected from 1019 moose (Alces alces), red deer (Cervus elaphus) and roe deer (Capreolus capreolus), shot during hunting (August-December) 2001-2003, are reported. The animals originated from 15 coastal municipalities (CM), seven municipalities bordering to coastal municipalities (BCM) and four inland municipalities (IM), in Norway, between latitudes 58-66° N. I. ricinus occurred endemically in all CM and BCM up to 63°30' N, whereas it was non-endemic further north and in the IM. This geographical distribution of the tick along the coast of southern Norway was largely in accordance with that reported as far back as the 1940s. Our results therefore did not indicate any large scale northwards expansion of I. ricinus in Norway during the 60 year-period between the two studies. However, the prevalence of infestation and tick abundance were significantly higher in CM as compared to BCM. The prevalence and abundance by month were highest during August and September, gradually decreasing towards December. The considerable prevalence of ticks in November, as well as findings in December, would seem to indicate a prolonged tick season as compared with the studies carried out 60 years ago. A total of 8920 ticks were isolated from 439 of the 603 animals examined in endemic municipalities, and the maximum number of ticks found on one single ear was 204. Attached adult ticks were primarily found among the long hairs at base of the ear, whereas nymphs and larvae were seen all over the outer surface of the pinna, for larvae especially at the edge and tip of the ear. Nymphs were the dominant instar, constituting 74% of the total tick count. The proportion of larvae and adult ticks was 13% and 12%. A significantly higher proportion of adult ticks and lower proportion of immature stages were found in moose, as compared to red deer and roe deer. The same apparently size-associated preference of adult ticks was also found for adult animals (all species) as compared to calves. Other grossly detected ectoparasites included the lice Solenopotes burmeisteri in red deer and Damalinia meyeri in roe deer, and the deer ked fly, Lipoptena cervi, in moose and roe deer. This is believed to be the first systematic study on the instar composition by I. ricinus infestation in free-ranging cervids. The examination of ears from hunted cervids should be recognized as a rational way of obtaining data on the geographical distribution and abundance of this tick in nature.

Evidence of spread of the emerging infectious disease, finch trichomonosis, by migrating birds.

Finch trichomonosis emerged in Great Britain in 2005 and led to epidemic mortality and a significant population decline of greenfinches, Carduelis chloris and chaffinches, Fringilla coelebs, in the central and western counties of England and Wales in the autumn of 2006. In this article, we show continued epidemic spread of the disease with a pronounced shift in geographical distribution towards eastern England in 2007. This was followed by international spread to southern Fennoscandia where cases were confirmed at multiple sites in the summer of 2008. Sequence data of the ITS1/5.8S/ITS2 ribosomal region and part of the small subunit (SSU) rRNA gene showed no variation between the British and Fennoscandian parasite strains of Trichomonas gallinae. Epidemiological and historical ring return data support bird migration as a plausible mechanism for the observed pattern of disease spread, and suggest the chaffinch as the most likely primary vector. This finding is novel since, although intuitive, confirmed disease spread by migratory birds is very rare and, when it has been recognised, this has generally been for diseases caused by viral pathogens. We believe this to be the first documented case of the spread of a protozoal emerging infectious disease by migrating birds.

A comparative study of hepatic trace element levels in wild moose, roe deer, and reindeer from Norway.

Liver samples from 422 wild moose (Alces alces), 280 roe deer (Capreolus capreolus), and 73 reindeer (Rangifer tarandus) collected by hunters in various localities in Norway, 2002-2003, were analyzed for the essential trace elements cobalt, copper (Cu), manganese (Mn), molybdenum, selenium (Se), and zinc. Significant differences in hepatic concentrations among species were found for all elements except for Mn, and considerable individual and geographic variations were seen. Roe deer had statistically significant lower Se levels (median: 0.51 µg Se/g dry weight) than did moose (0.77 µg Se/g) and reindeer (0.85 µg Se/g). Moose from two coastal municipalities with high precipitation had considerably higher Se concentrations than those from the other localities studied. Seventy-nine roe deer (28%) and 36 moose (9%) had Se concentrations below that regarded as deficient in domestic ruminants. The Se status in roe deer was lower than previously reported in Europe. Moose had a significantly higher Cu (222 µg Cu/g dw) than did roe deer (112 µg Cu/g) and reindeer (105 µg Cu/g). The Cu status of moose and roe deer in Norway are among the highest reported in Europe. However, a suboptimal Se and Cu status was found in moose from Tvedestrand, a population which has suffered from a reduced condition and productivity. The variability in trace element status among hunted cervids, with no apparent signs of deficiency or toxicity, probably reflects adaptations in these wild ruminant species to cope with this. However, subtle clinical signs and lesions are difficult to detect and further research is needed.

Serosurvey for canine distemper virus, canine adenovirus, Leptospira interrogans, and Toxoplasma gondii in free-ranging canids in Scandinavia and Svalbard.

Prevalence of antibodies reactive to canine distemper virus (CDV), canine adenovirus type 1 (CAV-1), Leptospira interrogans serovars Canicola and Icterohaemorrhagiae, and Toxoplasma gondii were examined in free-ranging Scandinavian canids. Sampling included 275 red foxes (Vulpes vulpes) from mainland Norway, 60 arctic foxes (Vulpes lagopus) from the high-arctic islands of Svalbard, and 98 wolves (Canis lupus) from the joint Swedish-Norwegian population. Methods used included virus neutralization tests for CDV and CAV-1, a microscopic agglutination test for L. interrogans, and a direct agglutination test for T. gondii. High prevalence of antibody to CAV-1 was identified in red foxes (59.6%), wolves (67.7%), and arctic foxes (37.8%). The prevalence of antibody to CDV varied between 9.6% and 12.3% in the three species. Antibodies to L. interrogans serovar Icterohaemorrhagiae were found in 9.9% of the red foxes and 8.4% of the wolves sampled, whereas no antibody-positive arctic foxes were found. All animals were antibody-negative for L. interrogans serovar Canicola. Antibodies to T. gondii were found in 66.9, 51.7, and 18.6% of red foxes, arctic foxes and wolves, respectively. Significantly more adults than juveniles were antibody-positive for CDV in red foxes and arctic foxes, for CAV-1 in wolves, and for T. gondii in red foxes and wolves. There was a general tendency for adult female red foxes to have a higher prevalence of antibodies for CDV than adult males; this difference was statistically significant. The results indicate that CDV and CAV-1 are endemic in red foxes and wolves on the Scandinavian mainland and in arctic foxes on Svalbard. Although infection with L. interrogans serovar Icterohaemorrhagiae was relatively common in wild canids on mainland Norway, it was not found on Svalbard, where the maintenance host (Rattus norvegicus) is absent. All three species are commonly exposed to T. gondii through predation on infected intermediate hosts.

Microcystin poisoning in roe deer (Capreolus capreolus).

Acute cyanobacterial hepatotoxicosis in a wild roe deer (Capreolus capreolus) from Norway is reported. The diagnosis was based upon the demonstration of typical liver lesions and high liver concentrations of microcystins. The liver was markedly enlarged and histopathological examination revealed diffuse hepatocellular dissociation, degeneration and necrosis and perisinusoidal haemorrhage. Liquid chromatography-mass spectrometry demonstrated the presence of 1361 ng microcystin-YR, -LR and -RR per gram liver (wet weight). This is believed to be the first report of cyanobacterial intoxication in wild mammalian species as confirmed by demonstration of high toxin levels in the animal's tissues.

First report of epizootic trichomoniasis in wild finches (family Fringillidae) in southern Fennoscandia.

Forty-one outbreaks of mortality in wild finches were reported in southern Norway, Sweden, and Finland in the second half of 2008 (n = 40) and in February 2009 (n = 1). Greenfinches (Carduelis chloris) and occasional chaffinches (Fringilla coelebs) primarily were affected. Forty-eight greenfinches, eight chaffinches, one hawfinch (Coccothraustes coccothraustes), and one blue tit (Parus caeruleus) from 22 incidents were examined postmortem. Birds were in poor nutritional condition and had necrotizing ingluvitis, esophagitis, and/or oropharyngitis. Viable trichomonads with morphology consistent with Trichomonas gallinae were demonstrated successfully in 65% and 71% of fresh carcasses examined by culture and wet mount, respectively. No primary bacterial pathogens were detected. To our knowledge, this is the first report of epizootic trichomoniasis in wild finches in Europe outside of the UK.

Prevalence and subtypes of influenza A viruses in wild waterfowl in Norway 2006-2007.

The prevalence of influenza A virus infection, and the distribution of different subtypes of the virus, were studied in 1529 ducks and 1213 gulls shot during ordinary hunting from August to December in two consecutive years, 2006 and 2007, in Norway. The study was based on molecular screening of cloacal and tracheal swabs, using a pan-influenza A RT-PCR. Samples found to be positive for influenza A virus were screened for the H5 subtype, using a H5 specific RT-PCR, and, if negative, further subtyped by a RT-PCR for the 3'-part of the hemagglutinin (HA) gene, encompassing almost the entire HA2, and the full-length of the neuraminidase (NA) gene, followed by sequencing and characterization. The highest prevalence (12.8%) of infection was found in dabbling ducks (Eurasian Wigeon, Common Teal and Mallard). Diving ducks (Common Goldeneye, Common Merganser, Red-breasted Merganser, Common Scoter, Common Eider and Tufted Duck) showed a lower prevalence (4.1%). In gulls (Common Gull, Herring Gull, Black-headed Gull, Lesser Black-headed Gull, Great Black-backed Gull and Kittiwake) the prevalence of influenza A virus was 6.1%. The infection prevalence peaked during October for ducks, and October/November for gulls. From the 16 hemagglutinin subtypes known to infect wild birds, 13 were detected in this study. Low pathogenic H5 was found in 17 dabbling ducks and one gull.

Acute yew (Taxus) poisoning in moose (Alces alces).

Acute yew (Taxus) intoxication in a free-ranging moose (Alces alces) is reported. The moose was found dead without any signs of struggle and post mortem examination revealed general congestion, bilateral heart dilatation, and the presence of yew in rumen. The animal was found adjacent to a housing estate with unfenced gardens, surrounded by woods and open fields without native yew. The vast majority of the gardens contained cultivars of yew that had frequently been browsed upon. These were the most likely source of intoxication. This is believed to be the first report of yew intoxication in a wild animal species. It is concluded that yew intoxication may be an overlooked diagnosis in wild deer, and the general opinion that deer species are naturally resistant to many plant-associated toxins is discussed.

High tolerance to repeated cycles of freezing and thawing in different Trichinella nativa isolates.

Trichinella nativa is the most frequent Trichinella species in arctic wildlife and also the predominating species seen in Norwegian fauna. The adaptation of T. nativa to a cold climate is reflected by the well-documented freeze tolerance of its muscle larvae. The ability of the larvae to survive repeated freezing and thawing events has not however been elucidated and was investigated in the present study, using an Alaskan isolate and two isolates from coastal and inland Norway, respectively. Each T. nativa isolate was inoculated in foxes (Vulpes vulpes) and the muscle tissue obtained after 20 weeks was minced and divided into freezer bags. In the initial part of the study, the bags were exposed to either continuous freezing (-5 degrees C) for up to 7 weeks or freezing (-5 degrees C) for up to 7 weeks with seven overnight (+21 degrees C) thawing events. Once a week a bag was removed from each group, the meat was digested and muscle larvae isolated. In vitro assessment of larval viability was carried out based on larval motility (active vs non-active) and morphology, coiled (alive) or C-shaped (dead). Larval infectivity was subsequently bioassayed in mice, administering 500 larvae per mouse. The mice were euthanised 4 weeks post inoculation, the muscle digested and larvae per gram (lpg) and reproductive capacity index (RCI) were calculated. During the second part of the study, some of the minced fox muscle, exposed to the initial freeze protocol, was stored for a further 23 weeks at -18 degrees C prior to in vitro and in vivo assessment of larval viability and infectivity. The study demonstrated that Trichinella isolates originating from carnivores from higher northern latitudes expressed highest tolerance to freezing and that temperature fluctuations around freezing point, for up to 7 weeks, had little effect on larval infectivity. A negative effect of the initial repeated freeze-thaw events could be demonstrated once the larvae were exposed to longer periods of subsequent deep freezing. Furthermore, it was demonstrated that larval morphology and motility are not suitable for the assessment of infectivity of Trichinella larvae. It was concluded that bioassay in mice was the only suitable method currently available for assessing larval viability.