Out-of-season breeding of captive white-tailed deer

Although techniques to induce out-of-season breeding in deer with exogenous hormones are documented, a successful technique has not been developed for use with white-tailed deer (Odocoileus virginianus). The efficacy of using a combined treatment of melatonin, progesterone, and pregnant mare serum gonadotropin to advance seasonal estrus in captive white-tailed deer was tested. First estrus of 12 treated does (n = 16) occurred at least 57 days sooner than did those of 4 non-treated controls (mid-November). Previous estrus dates were known for 11 does, suggesting that their estrus was advanced by 37 to 119 days (X = 82 days). At first estrus, 12 does were bred to untreated bucks that had velvet-covered or recently polished antlers, resulting in a conception rate of 75%. Two does conceived when bred at second or third estrus. Two does failed to conceive when bred at first estrus and displayed no estrous cycling that year, but conceived out-of-season in subsequent years. These data document that this technique is useful for inducing successful, out-of-season breeding of captive white-tailed deer. Furthermore, we demonstrate that some bucks at our facility have adequate fertility and libido to impregnate does during midsummer.     

Congenital hypotrichosis in a white-tailed deer fawn from South Dakota

On 1 October 2001, a 4-mo-old male white-tailed deer (Odocoileus virginianus) fawn was collected in Day County, South Dakota (USA), by South Dakota Department of Game, Fish and Parks personnel. The fawn had sparse hair development on the ventral thorax, the lateral caudal and caudal aspects of the rear legs, the muzzle, around the eyes, and inside the ears. Remaining skin surfaces were devoid of hair. Histologic examination revealed normal hair follicle density although follicles were empty or contained keratin debris and fragments of hair shaft. The epidermis of the fawn was mildly thickened and melanin pigment was prominent within deep layers of the epidermis. Based on histologic examination, the deer was diagnosed with congenital hypotrichosis. Although this condition has been reported in domestic species and humans, this specimen represents the first documented case of congenital hypotrichosis in a cervid.     

Effects of chronic wasting disease on reproduction and fawn harvest vulnerability in Wisconsin white-tailed deer

Chronic wasting disease (CWD) is a fatal, transmissible spongiform encephalopathy that affects free-ranging and captive North American cervids. Although the impacts of CWD on cervid survival have been documented, little is known about the disease impacts on reproduction and recruitment. We used genetic methods and harvest data (2002-04) to reconstruct parentage for a cohort of white-tailed deer (Odocoileus virginianus) fawns born in spring 2002 and evaluate the effects of CWD infection on reproduction and fawn harvest vulnerability. There was no difference between CWD-positive and CWD-negative male deer in the probability of being a parent. However, CWD-positive females were more likely to be parents than CWD-negative females. Because our results are based on harvested animals, we evaluated the hypothesis that higher parentage rates occurred because fawns with CWD-positive mothers were more vulnerable to harvest. Male fawns with CWD-positive mothers were harvested earlier (>1 mo relative to their mother's date of harvest) and farther away from their mothers than male fawns with CWD-negative mothers. Male fawns with CWD-positive mothers were also harvested much earlier and farther away than female fawns from CWD-positive mothers. Most female fawns (86%) with CWD-positive mothers were harvested from the same section as their mothers, while almost half of male and female fawns with CWD-negative mothers were farther away. We conclude that preclinical stages of CWD infection do not prohibit white-tailed deer from successfully reproducing. However, apparently higher harvest vulnerability of male fawns with CWD-positive mothers suggests that CWD infection may make females less capable of providing adequate parental care to ensure the survival and recruitment of their fawns.     

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.     

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.     

Acute sarcocystosis in a captive white-tailed deer in Virginia

A 19-mo-old female captive white-tailed deer in a public wild animal park in Richmond (Virginia, USA) was necropsied and evaluated histologically following spontaneous death after a 1 wk period of lethargy in a captive herd of 22 deer. An acute necrotizing pneumonia was associated with intraendothelial protozoal schizonts that were identified immunohistochemically as Sarcocystis spp. This is the first confirmed report of acute sarcocystosis in a wild ruminant.     

Epidemiology of chronic wasting disease in captive white-tailed and mule deer

The natural occurrence of chronic wasting disease (CWD) in a 1993 cohort of captive white-tailed deer (Odocoileus virginianus) afforded the opportunity to describe epidemic dynamics in this species and to compare dynamics with those seen in contemporary cohorts of captive mule deer (O. hemionus) also infected with CWD. The overall incidence of clinical CWD in white-tailed deer was 82% (nine of 11) among individuals that survived >15 mo. Affected white-tailed deer died or were killed because of terminal CWD at age 49-76 mo (x = 59.6 mo, SE = 3.9 mo). Epidemic dynamics of CWD in captive white-tailed deer were similar to dynamics in mule deer cohorts. Incidence of clinical CWD was 57% (4/7) among hand-raised (HR) and 67% (4/6) among dam-raised (DR) mule deer; affected HR mule deer succumbed at 64-86 mo of age (x = 72 mo; SE = 5 mo), and affected DR mule deer died at age 31-58 mo (x = 41.3 mo; SE = 6.1 mo). Sustained horizontal transmission of CWD most plausibly explained epidemic dynamics, but the original source of exposures could not be determined. Apparent differences in mean age at CWD-caused death among these cohorts may be attributable to differences in the timing or intensity of exposure to CWD, and these factors appear to be more likely to influence epidemic dynamics than species differences. It follows that CWD epidemic dynamics in sympatric, free-ranging white-tailed and mule deer sharing habitats in western North American ranges also may be similar.     

Control of Psoroptes cuniculi in captive white-tailed deer with ivermectin-treated corn

Psoroptes cuniculi, the ear mite of domestic rabbits, was collected from captive white-tailed deer (Odocoileus virginianus). This is the first report of rabbit ear mite infestations in white-tailed deer in Oklahoma or Texas (USA). In addition to moderate infestations in their ears, two 4-yr-old bucks, two 3-yr-old does, and seven 4-yr-old does showed patchy areas of alopecia along the sides and brisket. Both bucks also had patchy areas of alopecia around the base of antlers. Ear mites were eradicated from all deer except from one doe by providing ivermectin-treated corn to the deer at a rate of 1,000 g (equivalent to 200 mcg/kg of ivermectin)/day/deer for several days. The ear mite infestation in the one doe was eradicated by intramuscularly injection with ivermectin at 400 mcg/kg. After treatment with the ivermectin and eradication of the mites, the alopecia improved and eventually was eliminated. The ivermectin-treated corn also controlled all internal nematode parasites in the deer.     

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.     

Prevalence of renal urolithiasis in a large, captive white-tailed deer herd

Prevalence of renal urolithiasis in a large, captive white-tailed deer (Odocoileus virginianus) herd was examined over a two-year period of time. In 1973, 1.3% of 225 deer examined had calculi in the renal pelvis and 4.4% had kidney lesions, either independent or in combination with the calculi. In 1974, prevalence increased and 5.9% of 354 deer had calculi and 6.5% had kidney lesions. Calculi and lesions affected all sex and age-classes. Involvement was both unilateral and bilateral with 23.8% having stones in both kidneys and 30.4% having lesions in both kidneys. Lesions and calculi occurred together in 42.8% of cases. Etiology is unknown, but possible relationships are discussed.     

Winter fawn survival in black-tailed deer populations affected by hair loss syndrome

Overwinter fawn mortality associated with hair loss syndrome (HLS) is anecdotally thought to be important in declines of Columbian black-tailed deer (Odocoileus hemionus columbianus) populations in Washington and Oregon (USA). We determined prevalence of HLS in black-tailed deer, September and April fawn:doe ratios, and minimum overwinter survival rates of fawns for selected game management units (GMUs) in western Washington from 1999 to 2001. Prevalence of HLS ranged from 6% to 74% in fawns and 4% to 33% in does. Minimum fawn survival ranged from 0.56 to 0.83 and was unrelated to prevalence of HLS in either does (r=0.005, P=0.991) or fawns (r=-0.215, P=0.608). The prevalence of HLS in either does or fawns was also unrelated to either fall fawn:doe ratios (HLS does: r=-0.132, P=0.779; HLS fawns: r=0.130, P=0.760) or spring fawn:doe ratios (HLS does: r=-0.173, P=0.711; HLS fawns: r=-0.020, P=0.963). However, the prevalence of HLS in does and fawns was strongly related (r=0.942, P=0.002), and GMUs with high prevalence of HLS had lower deer population densities (fawns: r=-0.752, P=0.031; does: r=-0.813, P=0.026). Increased overwinter mortality of fawns because of HLS was not supported by our data. Decreased production of fawns, increased summer mortality of fawns, or both were seen in six of eight study GMU-year combinations. Observed rates of productivity and minimum fawn survival were inadequate to maintain population size in five of eight study GMU-year combinations, assuming an annual doe survival rate of 0.75. The influence of deer condition and population health on adult survival, fawn production, preweaning fawn survival, parasitism, and prevalence of HLS in both fawns and adults need to be clarified to identify what factors are limiting black-tailed deer productivity.     

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.     

Effects of xylazine immobilization on biochemical and endocrine values in white-tailed deer

The effect of xylazine hydrochloride on biochemical and endocrine parameters in plasma was examined in adult white-tailed deer (Odocoileus virginianus (Zimmermann]. In the first experiment, seven animals were injected intramuscularly via a blowgun dart with 0.65 mg/kg xylazine (100 mg/ml) and were bled 10, 20, 30, and 60 min post-injection. In the second experiment, eight animals were manually restrained for the first blood sampling and then injected manually and bled as before. Plasma calcium (Ca), inorganic phosphorus (P), and alkaline phosphatase (AP) were measured spectrophotometrically. Plasma parathyroid hormone (PTH), calcitonin (CT), thyroxine (T4), triiodothyronine (T3), and cortisol were measured by radioimmunoassay. Plasma PTH, CT, T4, T3, and AP activity did not differ (P greater than 0.05) during the 1 hr period studied in either experiment. Plasma Ca and P decreased significantly (P less than 0.05) in the second experiment, whereas cortisol levels increased significantly (P less than 0.05) 10 min post-injection in both experiments. The results may have been due to a drug effect or a combined drug and stress effect. It is suggested that xylazine may be safely used as an anesthetic in measuring PTH, CT, T4 and T3, and plasma AP up to 60 min post-injection in deer. Caution should be taken in using xylazine as an anesthetic to study adrenocortical function.     

Effects of six fasciolicides against Fascioloides magna In white-tailed deer

Thirty-three white-tailed deer (Odocoileus virginianus) of various ages, both sexes, and in good physical condition were captured for anthelmintic evaluation of six compounds against the large American liver fluke, Fascioloides magna. Based on fluke mortality, hexachlorophene administered at the rate of 12 to 26 mg/kg of body weight was lethal to 5 of 10 mature flukes in seven deer. Nitroxynil at 11 to 24 mg/kg inhibited egg production, but did not kill mature flukes in eight deer. Rafoxanide at 12 to 25 mg/kg killed 6 of 8 (75%) immature flukes in eight deer, but was not effective against 17 mature flukes. Clioxanide at 16 to 38 mg/kg, diamphenethide at 255 to 280 mg/kg, and hexachloroethane at 463 to 629 mg/kg were not effective against F. magna in four, two and four deer, respectively. There was no indication that treatment with fasciolicides at the higher dose rates was more efficacious than at the lower dose rates. Detection of fluke eggs in the feces was a reliable method for diagnosing the presence of mature F. magna in deer prior to treatment, but was not reliable for measuring fasciolicidal activity of all compounds tested.     

Hematology, blood chemistry and selenium values of captive pronghorn antelope, white-tailed deer and American bison

Pronghorn were observed to have a significantly higher whole blood selenium concentration than either the white-tailed deer or bison. Pronghorn colloid values were significantly less than those of the bison, and approached statistical significance for the white-tailed deer. Differential white blood cell counts for the white-tailed deer were markedly different from those of the pronghorn and bison. The American bison had significantly higher cortisol values and lower T3 values than either the white-tailed deer or pronghorn.