Experimental infection of white-tailed deer (Odocoileus virginianus) with Mycobacterium avium subsp. paratuberculosis

Mycobacterium avium subsp. paratuberculosis (Map) is the causative agent of paratuberculosis or Johne's disease, a chronic enteric disease of domestic ruminants as well as some nondomestic ruminants. Paratuberculosis is characterized by a protracted subclinical phase followed by clinical signs such as diarrhea, weight loss, and hypoproteinemia. Fecal shedding of Map is characteristic of both the subclinical and clinical phases, and it is important in disease transmission. Lesions of paratuberculosis are characterized by chronic granulomatous enteritis and mesenteric lymphadenitis. Animal models of paratuberculosis that simulate all aspects of the disease are rare. Oral inoculation of 9-day-old white-tailed deer (Odocoileus virginianus) on 3 June 2002 with 1.87 x 10(10) colony-forming units of Map strain K10 resulted in clinical disease (soft to diarrheic feces) as early as 146 days after inoculation; lesions consistent with paratuberculosis were observed in animals at the termination of the study. Intermittent fecal shedding of Map was seen between 28 and 595 days (4 March 2004) after inoculation. These findings suggest that experimental oral inoculation of white-tailed deer fawns may mimic all aspects of subclinical and clinical paratuberculosis.     

Aerosol exposure of white-tailed deer (Odocoileus virginianus) to Mycobacterium bovis

Tuberculosis due to Mycobacterium bovis affects both captive and free-ranging Cervidae in the United States. Various animal models have been developed to study tuberculosis of both humans and animals. Generally, tuberculosis is transmitted by aerosol and oral routes. Models of aerosol exposure of large animals to M. bovis are uncommon. In order to develop a reliable method of aerosol exposure of white-tailed deer (Odocoileus virginianus) to M. bovis, 12 healthy white-tailed deer, aged 8-10 mo, were infected by aerosol exposure to 2 x 10(5) to 1 x 10(6) colony forming units (CFU) (high close, n = 4) of M. bovis or 6 x 10(2) to 1.6 x 10(3) CFU (low dose, n = 8) of M. bovis. Tuberculous lesions were more widely disseminated in (leer receiving the high dose, while lesions in deer receiving the low dose were more focused on the lungs and associated lymph nodes (tracheobronchial and mediastinal). Aerosol delivery of M. bovis to white-tailed deer results in a reliable manner of experimental infection that may be useful for studies of disease pathogenesis, immune response, mycobacterial shedding, and vaccine efficacy.     

Congenital osteopetrosis in white-tailed deer (Odocoileus virginianus)

Inferior brachygnathia in neonatal fawns occurred sporadically over a 10 yr period in a captive herd of white-tailed deer (Odocoileus virginianus) in southern Ontario. Two fawns submitted for necropsy had marked inferior brachygnathia, protruding tongues, and fractured long bones. Radiographs of the limbs revealed longitudinal striations of relatively translucent immature woven bone that caused loss of distinction between medullary cavities and cortices. Microscopically, there was failure of remodelling of the primary spongiosa and filling of the medulla by cone-shaped chondro-osseous cores. The findings supported a diagnosis of osteopetrosis, usually a hereditary disease characterized by absence of marrow cavities as a result of defective bone remodelling. Osteopetrosis has not been reported previously in deer.     

Hyperkalemia in free-ranging white-tailed deer (Odocoileus virginianus)

Sixty adult and yearling female white-tailed deer (Odocoileus virginianus) were collected in July 2008 (n=30) and March 2009 (n=30) from eastern North Carolina as part of a population health assessment. During July 2008, standard serum analyses revealed hyperkalemia in all deer sampled. In March, the effect of processing time as a possible source of the hyperkalemia was investigated. For a subset of deer (n=10), blood tubes were centrifuged and processed at four time points (0, 30, 60, and 120 min) postcollection. Delayed centrifugation and plasma separation did not affect potassium (K(+)) concentration over time, indicating that a shift in intracellular K(+) did not occur and the hyperkalemia was not due to improper sample handling. Potassium levels were negatively correlated with age and varied across collection periods. Also, K(+) levels were positively correlated with glucose and not correlated with creatine kinase (CK). No single variable indicated a strong enough relationship to explain the hyperkalemia in the study.     

Xylazine hydrochloride for immobilizing captive white-tailed deer (Odocoileus virginianus)

White-tailed deer (Odocoileus virginianus) were immobilized with intramuscular doses of xylazine hydrochloride to facilitate blood sampling. Injection was either remotely by modified dart syringe or manually by hand syringe. In 86 attempts to immobilize female deer (aged 2, 5–6 yr) 73.3% were effectively immobilized for 90 min while 108 attempts to immobilize male deer (aged 2–3 yr) for at least 30 min resulted in 94.4% effective immobilization. Induction times averaged approximately 10 min for both sexes. Treated deer exhibited sedation, hypothermia, reduced respiration rates, anorexia, salivation, tongue paralysis and diarrhea. Deer also showed a loss or partial loss of pedal, palpebral, corneal, and swallowing reflexes during immobilization. Side effects of xylazine and length of immobilization appeared to be dose dependent. Mortality as a result of xylazine immobilization was four male deer out of a total of 194 immobilizing attempts on both sexes. Recommendations are given concerning care of deer during immobilization and recovery.     

Nitric oxide production as an indication of Mycobacterium bovis infection in white-tailed deer (Odocoileus virginianus)

White-tailed deer (Odocoileus virginianus) are reservoirs for Mycobacterium bovis in northeast Michigan, USA. Production of nitric oxide (NO) by activated macrophages is a potent mechanism of mycobacterial killing. The capacity of macrophages to produce NO, however, varies among mammalian species. The objective of this study was to determine if mononuclear cells from white-tailed deer produce nitrite as an indication of NO production and, if so, is NO produced in response to stimulation with M. bovis antigens. Supernatants were harvested from adherent peripheral blood mononuclear cell (PBMC) cultures that had been stimulated with either Mannheimia haemolytica lipopolysaccharide (LPS) or media alone (i.e., no stimulation). Nitrite levels within M. haemolytica LPS-stimulated culture supernatants exceeded (P < 0.05) those detected within supernatants from non-stimulated cultures as well as those detected within supernatants from cultures receiving an inhibitor of NO synthase in addition to M. haemolytica LPS. In response to stimulation with M. bovis antigens, nitrite production by PBMC from M. bovis-infected deer exceeded (P < 0.05) the production by PBMC from non-infected deer. The response of PBMC from infected deer to M. bovis antigens exceeded (P < 0.05) the response of parallel cultures from the same deer receiving no stimulation. The response of PBMC from M. bovis-infected deer to M. avium antigens did not differ from that of PBMC from M. bovis-infected deer to no stimulation or from that of PBMC from non-infected deer to M. avium antigens. These findings indicate that adherent PBMC from white-tailed deer are capable of NO production and that mononuclear cells isolated from M. bovis-infected white-tailed deer produce NO in an antigen-specific recall response.     

Immune responses of white-tailed deer (Odocoileus virginianus) to Mycobacterium bovis BCG vaccination

The objective was to evaluate cellular immune response of captive white-tailed deer (Odocoileus virginianus) to live Mycobacterium bovis bacille Calmette Guerin (BCG) vaccination and to determine diagnostic implications of these responses. In vitro proliferative and interferon-gamma (IFN-gamma) responses to M. bovis purified protein derivative (PPD) were detected beginning 9 days postvaccination. Responses to Mycobacterium avium PPD, however, generally exceeded responses to M. bovis PPD. Interferon-gamma responses to M. avium PPD were not detected prior to vaccination nor in nonvaccinated deer, suggesting that vaccination with BCG boosted prior quiescent M. avium-sensitized cells. Both CD4+ and gammadelta T cells from vaccinated deer proliferated in response to M. bovis PPD stimulation. Intradermal administration of M. bovis PPD resulted in increases in skin thickness of vaccinated deer beginning 24 hr postinjection. Such early reactions were characterized by edema and minimal mononuclear cell infiltration, whereas later reactions (i.e., 72 hr postinjection) were more typical of delayed type hypersensitivity. Upon in vitro activation with pokeweed mitogen, CD44 expression increased and CD62L expression decreased on lymphocytes from deer regardless of vaccination status. Likewise, M. bovis PPD stimulation of lymphocytes from vaccinated deer resulted in increases in CD44 expression and decreases in CD62L expression. These findings demonstrate the potential of BCG vaccination to elicit strong cell-mediated immune responses and appropriate alterations in CD44 and CD62L expression with in vitro stimulation of white-tailed deer lymphocytes. In relation to M. bovis diagnosis, vaccination of white-tailed deer with BCG can induce skin test responses that classify the animal as a tuberculosis reactor. In contrast, BCG vaccination will likely not interfere with tuberculosis testing by the IFN-gamma assay.     

Pulmonary mycoplasmosis in farmed white-tailed deer (Odocoileus virginianus)

An outbreak of respiratory disease at a farmed cervid facility resulted in isolation and identification of Mycoplasma boris in four affected white-tailed deer (Odocoileus virginianus) fawns. Microscopically, pulmonary lesions similar to those associated with M. bovis infections in calves, inclulding lymphoplasmacytic peribronchiolar cuffing and caseonecrotic bronchiectasis, were present. Arcanobacterium pyogenes was recovered from lung tissue as well. This report indicates that M. bovis can be associated with respiratory disease in white-tailed deer.     

Staphylococcal arthritis in a white-tailed deer (Odocoileus virginianus)

A five and one-half year old deer (Odocoileus virginianus) developed an ankylosing periarticular hypertrophic arthritis due to a coagulase positive staphylococcus infection. Complete encasement of the tibio-tarsal (hock) joints with a hypertrophic, and porous osseous mass had occurred with complete loss of articular cartilage. The pathologic alterations of the tissues are compared to those occurring in swine due to Erysipelothrix insidiosa infection which produces a rheumatoid-like arthritis.     

Cranial osteochondroma in a white-tailed deer (Odocoileus virginianus)

A large osteochondroma of the skull was diagnosed in a young adult free-ranging white-tailed deer (Odocoileus virginianus) from Wyoming. The 4.8-kg neoplasm primarily involved the left frontal bone with extension into the cranial cavity. Microscopically, the neoplasm was composed of well differentiated trabecular bone and islands of cartilage. This neoplasm is rare in domestic species and has not been reported in cervids. Though benign in morphology, the location and size of the neoplasm was probably responsible for debilitation of the deer.     

Theileriosis in a white-tailed deer (Odocoileus virginianus) fawn

A white-tailed deer (Odocoileus virginianus) fawn was collected in Missouri (USA) and submitted for diagnostic evaluation. Necropsy and histologic examination revealed severe Amblyomma americanum infestation, pronounced icterus, and marked hemosiderin deposition in the liver and spleen. Whole blood evaluation revealed a normocytic normochromic anemia and a piroplasm parasitemia of approximately 70%. The piroplasm was identified as Theileria cervi by polymerase chain reaction and sequencing of the V4 variable region of the 18S rRNA gene from a paraffin-embedded section of lung. Although T. cervi parasitemias have been commonly reported in healthy white-tailed deer, the severe parasitemia in this fawn may have contributed to overt clinical disease, perhaps as part of a combined malnutrition and parasitemia syndrome.     

Maxillary lymphosarcoma in a white-tailed deer (Odocoileus virginianus)

In 1996, lymphosarcoma was observed in a captive adult female white-tailed deer (Odocoileus virginianus) from northeastern Kansas (USA). A subcutaneous mass on the deer's left cheek was surgically removed and lymphosarcoma was diagnosed. The mass recurred within 3 wk. A second surgical removal was attempted but the tumor had grown much larger, had become intimately involved with the buccal mucosa, and was beginning to interfere with mastication. For these reasons, the deer was euthanized. At postmortem examination the only abnormal findings were the primary tumor and enlarged ipsilateral parotid and mandibular lymph nodes. Histologically these tissues demonstrated changes characteristic of lymphosarcoma but no other organs had evidence of neoplastic disease. A diagnosis of focal lymphosarcoma with local metastasis was made. The organ distribution of lymphosarcoma in this deer differs from previously described cases of lymphosarcoma in cervids.     

Cranial suture complexity in white-tailed deer (Odocoileus virginianus)

Neurocranial expansion and mastication are commonly implicated as the two major biomechanical factors affecting suture morphology. In deer the antlers provide an additional source of biomechanical stress acting on the skull. Equivalent stresses are not found in females, who lack antlers. We analyzed the complexity and interdigitation of the interfrontal and coronal sutures that surround the antler-bearing frontal bones of (n = 67) white-tailed deer (Odocoileus virginianus) to 1) evaluate changes in suture morphology throughout ontogeny, and 2) test the hypothesis that male deer have more complex sutures than females. Two methods were used to quantify suture morphology: fractal analysis and length-ratios (actual suture length divided by direct straightline length). Both techniques produced similar results, although the two methods cannot be considered equivalent. Suture complexity increases markedly throughout ontogeny, but appears to level off after animals have reached adulthood. Cranial size in males, but not females, continues to increase in adults. No significant increase in suture complexity with age in the adult cohort was detected. While deer are highly dimorphic in size and the presence of antlers, no significant differences existed between males and females for any measure of suture complexity. No consistent patterns emerged between suture complexity and skull size or antler characteristics. The presence of antlers appears to have a minimal effect on suture complexity in white-tailed deer. Factors that may contribute to the lack of dimorphism in suture complexity are discussed.     

Gastro-intestinal helminths in white-tailed deer (Odocoileus virginianus) of Illinois.

Two deer populations, one in northern Illinois the other in southern Illinois, were examined by necropsy (n = 44 and 40 respectively) for helminth parasites of the gastro-intestinal tract and abdominal cavity. Both herds were parasitized by Apteragia odocoilei, Haemonchus contortus, Gongylonema pulchrum, Setaria yehi, Trichuris ovis, and Moniezia benedeni. Nematodirus sp. was found only in deer of northern Illinois. Ostertagia mossi, Capillaria sp., Cooperia sp., and Oesophagostomum sp. were found only in deer of southern Illinois.     

Atlantoaxial instability in a white-tailed deer fawn (Odocoileus virginianus)

On 14 March 2001, an 8 mo old, male white-tailed deer (Odocoileus virginianus) was found in lateral recumbency exhibiting neurologic signs including inability to rise, opisthotonus, paddling, and respiratory distress. There was evidence of minor cranial trauma. Postmortem examination revealed atlantoaxial instability with ventral deviation of the axis due to malformation of the caudal atlas and cranial axis. Given the age of the fawn, the instability was assumed to be congenital with minor trauma inducing severe, acute neurologic signs.     

Testing a molasses-based bait for oral vaccination of white-tailed deer (Odocoileus virginianus) against Mycobacterium bovis

White-tailed deer (Odocoileus virginianus) in Michigan, USA, are wildlife reservoirs of bovine tuberculosis (bTB) with documented spread to cattle. In vaccine efficacy trials, Mycobacterium bovis bacillus Calmette–Guerin (BCG) administered orally reduces colonization and bTB-associated lesions in white-tailed deer after experimental challenge with virulent M. bovis. The objective of this study was to develop and evaluate the palatability of a molasses-based bait for oral delivery of BCG to white-tailed deer. Relevant practical properties of the bait such as physical stability under various environmental conditions were evaluated, as well as palatability. Captive deer consumed baits within 3 h of introduction during 48 of 50 trials. Digital game cameras revealed consumption of all placed baits by one deer over 62 % of the time. Addition of BCG vaccine did not negatively impact palatability. Physical stability analysis demonstrated that ice and water significantly reduced bait stability as measured with a compression assay. Storage of BCG-containing baits at 4 °C showed a slight decrease in colony-forming units (CFUs) by day 31. In contrast, storage at ?20 or ?80 °C over the same 31-day period showed no significant decrease in BCG viability. The results of this study suggest that molasses-based baits, as prepared here, represent a plausible means of oral delivery of BCG to white-tailed deer under most environmental conditions.     

Effects of fluoride ingestion on white-tailed deer (Odocoileus virginianus)

The effects of the addition of 25 or 50 ppm fluoride (F), as sodium fluoride (NaF), to the rations of 5-mo-old male white-tailed deer were similar to those observed in domestic cattle fed similar amounts of fluoride. The ingestion of 50 ppm F for 2 yr resulted in the accumulation of over 7,000 ppm F in bone ash. Accumulation of fluoride in antlers was extensive and occurred more rapidly than in skeletal tissue. Fluoride ingestion resulted in lesions on the developing incisors that were similar, but not identical to those seen in other species. Increased molar wear in the deer fed 50 ppm F was minimal, and no gross pathology of the mandible was observed. Only mild hyperostosis of the long bones was evident.     

Survival of Mycobacterium bovis on feedstuffs commonly used as supplemental feed for white-tailed deer (Odocoileus virginianus)

Mycobacterium bovis, the causative agent of bovine tuberculosis, has become established in free-ranging white-tailed deer Odocoileus virginianus in northeastern Michigan. The practice of supplemental feeding of white-tailed deer during the winter is believed to contribute to transmission of M. bovis between deer. The current study was conducted to determine the ability of M. bovis to survive on various feedstuffs commonly used as supplemental feed for deer in northeast Michigan (i.e., apples, corn, carrots, sugar beets, potatoes, and hay) and the effect of maintenance at -20 C, 8 C, and 23 C on survival. Mycobacterium bovis survived on all feedstuffs at all temperatures tested for at least 7 days. At 23 C, M. bovis could still be isolated from samples of apples, corn and potatoes at 112 days. This study suggests that contamination of feedstuffs by M. bovis-infected deer could act as a source of indirect transmission between deer because M. bovis is able to survive in temperatures similar to those recorded during winter months in northeastern Michigan. Current efforts to ban or control supplemental feeding of deer should have a positive effect on decreasing transmission of M. bovis among deer.