The effect of yohimbine on plasma levels of T3, T4 and cortisol in xylazine-immobilized white-tailed deer

1. The effect of yohimbine (Y) on blood levels of thyroxine (T4), triiodothyronine (T3), and cortisol was investigated in 5 mature male white-tailed deer immobilized with xylazine hydrochloride (X). 2. T4 levels were erratic in X-treated deer, but stabilized in the X- and Y-treated deer. 3. T3 remained unchanged in both groups. 4. Cortisol levels have increased in X-treated deer, but declined in X- and Y-treated deer. 5. Yohimbine is a potent and safe antidote of X not affecting T3 and T4. Caution should be used in using R or Y in cortisol studies.     

Plasma levels of beta-endorphin in white-tailed deer: seasonal variation and the effect of thyroxine, GnRH, dexamethasone and ACTH administration

1. A distinct seasonal cycle of beta-endorphin (beta-E) was detected in plasma of four intact, male white-tailed deer. Peak levels (around 11 pg/ml) were observed in August and minimal concentrations (around 5 pg/ml) were detected in January and February. 2. The seasonal variation (which corresponds to intensity of antler growth) was more pronounced in the two mature bucks, as compared to the immature ones. 3. Intramuscular administration of synthetic thyroxine (in doses of 500, 750 and 1000 micrograms/deer) and GnRH (100 micrograms/deer) had generally no significant effect on the beta-E levels. 4. I.v. administration of dexamethasone (5 mg/deer) as well as i.m. injection ACTH (20 Int. Units/deer) significantly reduced beta-E levels.     

Circadian and circannual rhythms of melatonin in plasma of male white-tailed deer and the effect of oral administration of melatonin

Circadian levels of melatonin (M) were determined in plasma of four male white-tailed deer sampled hourly in September for 24 h via indwelling jugular catheter. Concentrations of M, detected by the radioimmunoassay rise with the onset of darkness, peak at 1.00 h (265 pg/ml) and then quickly decline to baseline levels (60 to 70 pg/ml) maintained during the scotophase. Orally administered M (5 mg, given at 13:00 h) induced a rapid elevation of plasma M (peak 980 pg/ml at 15:00 h) followed by a decline to baseline (100 pg/ml) reached at 22:00 h. The usual midscotophase peak was abolished by exogenous M administration. Seasonal midscotophase levels of M (determined in three samples taken 45 min apart between 23:00 and 1:00 h reach maximum in December (1530 pg/ml) followed by decline to minimum (69 to 90 pg/ml) observed between May and July. The data indicate that: 1) similarly to other mammals, deer exhibit peak levels of M during the dark phase; 2) 5 mg of M given orally caused a rapid elevation of M levels in blood followed by a depression of the normally present night-time peak; and 3) midscotophase levels of M exhibit very pronounced seasonal fluctuations which might be related to yearly cycles, such as the reproduction, hair molt, and antler growth.     

Circadian and circannual rhythms of LH, FSH, testosterone (T), prolactin, cortisol, T3 and T4 in plasma of mature, male white-tailed deer

Circadian and circannual rhythm of plasma LH, FSH, testosterone (T), prolactin, cortisol, triiodothyronine (T3) and thyroxine (T4) were investigated in two mature male white-tailed deer. No circadian rhythms were detected. Seasonal levels of LH and FSH were reached in September and October; troughs occur in May and June. Maximal T values were detected in November and December (the time of the rut); minimal levels occur between February and July. Prolactin peaked in May and June; minimal levels were detected between October and February. T3 exhibited two maxima; the first in the May-June period, the second in the September-October period. T4 showed no recognizable circannual rhythm. Cortisol levels were found to be much higher during cold months (December-April) than during the rest of the year. The least variable circadian levels were that of FSH and prolactin, with LH, T4, T3, cortisol and testosterone following in descending order. Cannulation stress might have some effect on the levels of testosterone, LH and cortisol. Correlation between LH and testosterone levels were detected mainly during sexually active periods.     

Seasonal levels of minerals, enzymes, nutrients and metabolic products in plasma of intact and castrated adult male white-tailed deer (Odocoileus virginianus)

1. Alkaline phosphatase (AP), cholesterol, creatinine, uric acid, total protein, albumin, bilirubin, urea nitrogen, calcium, glucose, lactic dehydrogenase (LDH) and serum glutamic-oxalacetic transaminase (SGOT) were measured in the plasma of three intact and three castrated male deer. 2. A statistically significant seasonal cycle of AP, cholesterol, creatinine and uric acid was found in intact but not in castrated animals. 3. Monthly levels of total protein, albumin, urea nitrogen, bilirubin and calcium were significantly higher in castrated deer. 4. On the other hand, monthly levels of LDH and SGOT were higher in intact animals.     

Thyroxine levels and antler growth in white-tailed deer

1. Five normal male, 5 female, and 3 castrated fawns and 5 adult male white-tailed deer were housed in individual pens for one year to compare the relationships between thyroxine (T4) and other blood parameters and the antler cycle. 2. Biweekly serum samples were examined for T4 titers and levels of serum calcium (Ca), inorganic phosphorus (P), and alkaline phosphatase activity (AP). 3. Seasonal T4 changes were found in all deer groups, with elevated titers in the fall. Female fawns had overall lowered T4 levels. In male fawns and adult bucks, T4 seemed to play a synergistic role in antler initiation and growth. 4. Serum Ca levels remained constant throughout the year, but with lower levels in the female fawns. 5. Serum P levels were also constant seasonally, but with higher levels in the female fawns. There was no age effect on either Ca or P. 6. An age effect was evident on plasma alkaline phosphatase with lower activity in adult bucks. There was no sex effect on AP activity. 7. T4 might have an indirect association with the enzyme AP in Ca and P transport system in white-tailed deer.     

Fertility in an F1 male hybrid of white-tailed deer (Odocoileus virginianus) x mule deer (O. hemionus)

The fecundity of an F1 male hybrid deer, from a cross between a male Odocoileus virginianus (white-tailed deer) and a female O. hemionus (mule deer), was assessed by cytogenetic and flow cytometric techniques. Analysis of chromosome morphology, nucleolus organizer expression, meiotic chromosome pairing, sperm production, and nuclear gene inheritance revealed no genetic anomalies that could potentially impair normal fertility. These observations are discussed in relation to recent reports of hybridization between natural populations of these two species.     

The effect of artificial photoperiodicity and antiandrogen treatment on the antler growth and plasma levels of LH, FSH, testosterone, prolactin and alkaline phosphatase in the male white-tailed deer

1. Artificial extension of day-length in adult male white-tailed deer during the autumn induced: (a) premature casting of antlers, early onset of the new antler growth and out of season mineralization, (b) early elevation of plasma levels of prolactin, LH, FSH, testosterone and alkaline phosphatase and (c) out of season hair molt. 2. Intramuscular administration of the antiandrogen cyproterone acetate immediately after velvet shedding induced: (a) dramatic reduction of testosterone levels in plasma, (b) premature casting in bucks with fully mineralized antlers and (c) renewal of bone rebuilding activity in incompletely mineralized antlers which resulted in blockage of casting.     

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.     

Chronic exposure to short photoperiod inhibits free thyroxine index and plasma levels of TSH, T4, triiodothyronine (T3) and cholesterol in female Syrian hamsters

1. Chronic exposure of female Syrian hamsters (Mesocricetus auratus) for 9 weeks to a short photoperiod (10L:14D) depressed the pituitary-thyroid axis as indicated by a drop in circulating titers of thyroid stimulating hormone (TSH), thyroxine (T4), triiodothyronine (T3) and the free thyroxine index (FT4I) compared to animals maintained under long photoperiodic conditions (14L:10D). 2. Short day treatment also reduced plasma cholesterol levels. 3. Neither plasma triglycerides, glucose nor growth hormone (GH) levels differed between hamsters exposed to short or long daily photoperiods.     

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.     

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.     

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.     

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.     

Environmental effect on plasma thyroxine (T4), 3,5,3'-triido-L-thyronine (T3), prolactin and cyclic adenosine 3',5'-monophosphate (cAMP) content in the mudskippers Periophthalmus chrysospilos and Boleophthalmus boddaerti

1. In both Periophthalmus chrysospilos and Boleophthalmus boddaerti, T4 was involved in enabling the fish to cope with terrestrial stress and not in osmoregulation in waters of different salinities. In B. boddaerti, however, 3,5,3'-triiodo-L-thyronine (T3) played a more significant role in osmoregulation under the various aquatic conditions. 2. The control of osmoregulation mechanisms in P. chrysospilos kept in waters of different salinities was taken over by prolactin instead, whereas prolactin was only involved in osmoregulation in B. boddaerti under extreme osmotic stress (100% SW). Prolactin is also involved in the terrestrial adaptations of P. chrysospilos. 3. Plasma cAMP levels in P. chrysospilos increased with increasing salinity of the external environment (Tables 4 and 5) implicating its role in the stimulation of chloride secretion and in intracellular isosmotic regulation. 4. Significant increase in the plasma cAMP level of B. boddaerti submerged in 100% SW was also observed. However, the plasma cAMP levels of B. boddaerti fully submerged in 30% and 50% SW were not significantly different from the control as these conditions simulated those of their natural habitats.