Free-ranging Wolves Research Articles

Domestic Dog Origin of Canine Distemper Virus in Free-ranging Wolves in Portugal as Revealed by Hemagglutinin Gene Characterization

Serologic evidence for canine distemper virus (CDV) has been described in grey wolves but, to our knowledge, virus strains circulating in wolves have not been characterized genetically. The emergence of CDV in several non-dog hosts has been associated with amino acid substitutions at sites 530 and 549 of the hemagglutinin (H) protein. We sequenced the H gene of wild-type canine distemper virus obtained from two free-ranging Iberian wolves (Canis lupus signatus) and from one domestic dog (Canis familiaris). More differences were found between the two wolf sequences than between one of the wolves (wolf 75) and the dog. The latter two had a very high nucleotide similarity resulting in identical H gene amino acid sequences. Possible explanations include geographic and especially temporal proximity of the CDV obtained from wolf 75 and the domestic dog, taken in 2007-2008, as opposed to that from wolf 3 taken more distantly in 1998. Analysis of the deduced amino acids of the viral hemagglutinin revealed a glycine (G) and a tyrosine (Y) at amino acid positions 530 and 549, respectively, of the partial signaling lymphocytic activation molecule (SLAM)-receptor binding region which is typically found in viral strains obtained from domestic dogs. This suggests that the CDV found in these wolves resulted from transmission events from local domestic dogs rather than from wildlife species.

Hematology and serum clinical chemistry reference intervals for free‐ranging Scandinavian gray wolves (Canis lupus)

Scandinavian free-ranging wolves (Canis lupus) are endangered, such that laboratory data to assess their health status is increasingly important. Although wolves have been studied for decades, most biological information comes from captive animals. The objective of the present study was to establish reference intervals for 30 clinical chemical and 8 hematologic analytes in Scandinavian free-ranging wolves. All wolves were tracked and chemically immobilized from a helicopter before examination and blood sampling in the winter of 7 consecutive years (1998-2004). Seventy-nine blood samples were collected from 57 gray wolves, including 24 juveniles (24 samples), 17 adult females (25 samples), and 16 adult males (30 samples). Whole blood and serum samples were stored at refrigeration temperature for 1-3 days before hematologic analyses and for 1-5 days before serum biochemical analyses. Reference intervals were calculated as 95% confidence intervals except for juveniles where the minimum and maximum values were used. Significant differences were observed between adult and juvenile wolves for RBC parameters, alkaline phosphatase and amylase activities, and total protein, albumin, gamma-globulins, cholesterol, creatinine, calcium, chloride, magnesium, phosphate, and sodium concentrations. Compared with published reference values for captive wolves, reference intervals for free-ranging wolves reflected exercise activity associated with capture (higher creatine kinase activity, higher glucose concentration), and differences in nutritional status (higher urea concentration).

First Record of Entodiniomorph Ciliates in a Carnivore, the Maned Wolf (Chrysocyon brachyurus), from Brazil

The entodiniomorph ciliates (Ciliophora: Entodiniomorphida) are endosymbiotes widely found in the intestines of herbivorous mammals. These commensals commonly occur in the Artiodactyla and Perissodactyla and have also been described in the Proboscidea, Primates, Rodentia, and Diprotodontia. This study reports the first finding of a ciliate in a member of order Carnivora, the maned wolf (Chrysocyon brachyurus). Fecal samples from wild and captive maned wolves were screened using ethyl acetate sedimentation. Prevalence in fecal samples collected from free-ranging maned wolves in Brazil was 40% (6 of 15). Fecal samples from two of four captive individuals from the St. Louis Zoo also had the same species of ciliate. The largely frugivorous diet of the maned wolf likely explains the occurrence of these normally herbivore-associated endosymbiotes in a carnivore.

Prevalence of Crown Trauma in Free-Ranging Maned Wolves (Chrysocyon Brachyurus) in Central Brazil

Nineteen free-ranging maned wolves (Chrysocyon brachyurus) were captured in central Brazil from April through November 2003. Oral cavity examination revealed 34 teeth with crown trauma in twelve animals. Canine teeth were most commonly affected (44.2%), followed by premolar (29.4%) and incisor teeth (26.5%). Trauma to maxillary teeth (67.7%) was more frequent compared with mandibular teeth (32.3 %). The majority of dental fractures were located at the cuspid portion of the crown (56.0%). Slab fractures were the most frequent type (37.0%), followed by horizontal (24.0%), oblique (24.0%) and longitudinal fractures (15.0%). Complicated crown fracture (pulp exposure) was diagnosed in 13 (38.2%) of these teeth while pulpitis noted by tooth discoloration was diagnosed in 8 (23.5%) teeth.

Diets of Free-Ranging Mexican Gray Wolves in Arizona and New Mexico

Systematic diet studies of Mexican gray wolves (Canis lupus baileyi) were not conducted before wolves were extirpated by the late 1960s from the southwestern United States. We collected carnivore scats (n = 1,682) from the Apache and Gila national forests in Arizona and New Mexico, USA, from April 1998 through October 2001 and identified scats to species using traditional field methods, of which 251 were identified as Mexican wolf scats. We found the diet consisted of large-sized food items (92.8% percent frequency of occurrence [PFO]), primarily elk (Cervus elaphus) adults (36.6% PFO) and calves (36.2% PFO). Biomass calculations indicated that Mexican wolves consumed 414 kg of prey as represented by the scats, with elk representing 76.7% of the biomass. When comparing PFO with percent biomass, PFO calculations may have underrepresented larger food items and percent biomass may have overrepresented smaller food items. We compared the diet composition of Mexican wolf scats (n = 251) to the diets reported in previous North American gray wolf (C. lupus) studies (n = 7). The high proportion of elk in Mexican wolf diets in our study area may reflect the low-density, early colonizing stage of the wolf population and elk probably being the most numerous ungulate in our study area. Our results suggested that free-ranging Mexican wolves consumed a higher proportion of large-sized prey than other North American gray wolves. Our results provide baseline diet information for a newly reestablished wolf population.

Howling activity of free-ranging wolves (Canis lupus) in the Białowieża Primeval Forest and the Western Beskidy Mountains (Poland)

We investigated spontaneous howling by radio-collared wolves Canis lupus inhabiting the Bialowieza Primeval Forest (BPF), eastern Poland, and elicited howling behavior in wolves of the BPF and the Western Beskidy Mountains, southern Poland. Over half (58%) of all spontaneous howls recorded throughout a year occurred in the period from July to October, with a peak in August. The daily pattern of vocal activity by wolves was characterised by a peak between 1800 and 0000 hours, which coincided with the first (dusk) peak of wolf mobility. Wolves howled from the core areas of their territories and not from the peripheries. Howls served as communication between temporarily separated pack mates (43% of cases), after re-union (18%) and before setting out for a hunt (22%). Very few spontaneous howls (2%) were targeted at a neighbouring pack. Wolves responded to human-simulated howling in June–September, with a peak in August (reply rate: 39%). The duration of elicited howling increased significantly with group size: howls by single wolves or pairs lasted, on average, 34–40 s, whereas those of five to seven wolves (including pups) had an average duration of 67–95 s, with a maximum length of nearly 4 min. In the populations of Polish wolves studied here, spontaneous howling served primarily for intra-pack communication. Nonetheless, the high reply rate to howling simulation showed that – if necessary – wolves readily advertised their presence in a territory to strangers.

Detecting introgressive hybridization between free‐ranging domestic dogs and wild wolves (Canis lupus) by admixture linkage disequilibrium analysis

Occasional crossbreeding between free-ranging domestic dogs and wild wolves (Canis lupus) has been detected in some European countries by mitochondrial DNA sequencing and genotyping unlinked microsatellite loci. Maternal and unlinked genomic markers, however, might underestimate the extent of introgressive hybridization, and their impacts on the preservation of wild wolf gene pools. In this study, we genotyped 220 presumed Italian wolves, 85 dogs and 7 known hybrids at 16 microsatellites belonging to four different linkage groups (plus four unlinked microsatellites). Population clustering and individual assignments were performed using a Bayesian procedure implemented in structure 2.1, which models the gametic disequilibrium arising between linked loci during admixtures, aiming to trace hybridization events further back in time and infer the population of origin of chromosomal blocks. Results indicate that (i) linkage disequilibrium was higher in wolves than in dogs; (ii) 11 out of 220 wolves (5.0%) were likely admixed, a proportion that is significantly higher than one admixed genotype in 107 wolves found previously in a study using unlinked markers; (iii) posterior maximum-likelihood estimates of the recombination parameter r revealed that introgression in Italian wolves is not recent, but could have continued for the last 70 (+/- 20) generations, corresponding to approximately 140-210 years. Bayesian clustering showed that, despite some admixture, wolf and dog gene pools remain sharply distinct (the average proportions of membership to wolf and dog clusters were Q(w) = 0.95 and Q(d) = 0.98, respectively), suggesting that hybridization was not frequent, and that introgression in nature is counteracted by behavioural or selective constraints.

Physical Characteristics, Hematology, and Serum Chemistry of Freeranging Gray Wolves, <em>Canis lupus</em>, in Southcentral Alaska

Examination of morphometric characteristics and blood parameters has become a widely used tool for assessing the physiological and nutritional status of wild and captive animals. During 1976 through 1984, 155 Gray Wolves (Canis lupus) were chemically immobilized in south-central Alaska. Of those, we obtained physical measurements from 132 and blood samples from 121 individuals. Also, 208 carcasses of harvested and dead radiocollared Wolves were weighed and measured. We obtained blood samples from three of the fresh carcasses. We measured age, body weight, skull length and width, and upper and lower canine length. We analyzed blood serum for Ca, P, Fe, chlorides, creatinine, glucose, lactic dehydrogenase, alkaline phosphatase, glutamic oxalic transaminase, triglyceride, beta globulin, serum urea nitrogen, and uric acid. We obtained packed cell volume and hemoglobin values from whole blood. We classified samples by season, sex, and age. Seasonal differences were observed for physical measurements, packed cell volume, alkaline phosphatase, and serum urea nitrogen. Age differences were observed for physical measurements, hemoglobin, packed cell volume, alkaline phosphatase, P, Ca, creatinine, serum urea nitrogen, and percent femur bone marrow fat. However, differences among sexes were observed for physical measurements only. These data provide a baseline for physical condition, hematology, and serum chemistry for free-ranging Gray Wolves.

IMMOBILIZATION OF FREE-RANGING MANED WOLF (CHRYSOCYON BRACHYURUS) WITH TILETAMINE AND ZOLAZEPAM IN CENTRAL BRAZIL

A tiletamine hydrochloride-zolazepam hydrochloride combination was used successfully to immobilize 27 free-ranging maned wolves (Chrysocyon brachyurus) at a mean dose of 2.77+/-0.56 (mean+/-SD) mg/kg. The induction time ranged from 3-15 min. Animals remained immobilized for periods of 48.56 +/-12.65 min. Compulsive licking, excessive salivation, muscle twitching, muscle tremors, tachypnea, and bradycardia were observed associated with the induction of the anesthesia in 13 of 27 maned wolves. Muscle twitching, pedal withdrawal reflex, muscle tremors, and ataxia were observed during recovery in three (11%) maned wolves. There were no significant differences in heart rates (P = 0.44), respiratory rates (P = 0.82), and rectal temperatures (P = 0.54) recorded at 5, 15, and 25 min after induction at these dosages. The tiletamine hydrochloride-zolazepam hydrochloride combination was shown to be an effective and safe immobilizing agent for free-ranging maned wolves.

AGE-RELATED BODY MASS AND REPRODUCTIVE MEASUREMENTS OF GRAY WOLVES IN MINNESOTA

Based on 65 free-ranging gray wolves (Canis lupus) of known age and 25 of estimated age examined during summers of 1970–2004 in northeastern Minnesota, body mass of both males and females peaked at 5 or 6 years of age, with mean masses of 40.8 kg and 31.2 kg, respectively. Testis size varied as a function of age and month through at least 8 years of age, with length plus width ranging from 1.9 to 7.8 cm. Most females aged 4–9 years bred based on assessment of nipple sizes; those that had not bred had average lower body mass than those that had. This is the 1st report of such data from known-aged wolves. Information about development and mass changes of freeranging gray wolves (Canislupus) has been scattered, anecdotal, or piecemeal. Primarily this has been because wolves are longlived, were scarce and difficult or expensive to live-capture (Mech 1974), and because aging techniques for live wolves had not been developed. Wolf pup growth and development was described for captive (Mech 1970; Pulliainen 1965) and freeranging (Van Ballenberghe and Mech 1975) animals. Seasonal mass change (Seal and Mech 1983) and nipple measurements (Mech et al. 1993) of wolves with known reproductive histories were documented for captive wolves but were not related to ages. Testis measurements separating yearling wolves from older animals have been published, but no data were presented for various-aged adults (Gese and Mech 1991). Testis size has been said to vary with season, but no data were given (Seal et al. 1987). However, as a result of a study in which free-ranging wolves have been livetrapped, examined, ear-tagged, and radiotagged from 1968 through 2004 (Mech 1979, 2000), enough knownaged pups were so marked and then recaptured as adults of various known ages that data are now available relating wolf measurements to age. In addition, the development of tooth-wear charts from known-aged wolves (Gipson et al. 2000) allowed accurate age estimates of livetrapped wolves, which yielded additional data (Mech, in press). I thus present here information about the body mass and testis and nipple measurements of freeranging Minnesota wolves of various ages.

EXPOSURE OF FREE-RANGING MANED WOLVES (CHRYSOCYON BRACHYURUS) TO INFECTIOUS AND PARASITIC DISEASE AGENTS IN THE NOËL KEMPFF MERCADO NATIONAL PARK, BOLIVIA

Maned wolves (Chrysocyon brachyurus) are neotropic mammals, listed as a CITES Appendix II species, with a distribution south of the Amazon forest from Bolivia, through northern Argentina and Paraguay and into eastern Brazil and northern Uruguay. Primary threats to the survival of free-ranging maned wolves include habitat loss, road kills, and shooting by farmers. An additional threat to the conservation of maned wolves is the risk of morbidity and mortality due to infectious and parasitic diseases. Captive maned wolves are susceptible to, and die from, common infectious diseases of domestic dogs (Canis familiaris) including canine distemper virus (CDV), canine parvovirus (CPV), rabies virus, and canine adenovirus (CAV). Results from this study show that free-ranging maned wolves in a remote area of Bolivia have been exposed to multiple infectious and parasitic agents of domestic carnivores, including CAV, CDV, CPV, canine coronavirus, rabies virus, Leptospira interrogans spp., Toxoplasma gondii, and Dirofilaria immitis, and may be at increased risk for disease due to these agents.

TRANSMISSION OF NEOSPORA CANINUM BETWEEN WILD AND DOMESTIC ANIMALS

To determine whether deer can transmit Neospora caninum, brains of naturally infected white-tailed deer (Odocoileus virginianus) were fed to 4 dogs; 2 of these dogs shed oocysts. Oocysts from 1 of the dogs were tested by polymerase chain reaction and found to be positive for N. caninum and negative for Hammondia heydorni. The internal transcribed spacer 1 sequence of the new strain (designated NC-deer1) was identical to N. caninum from domestic animals, indicating that N. caninum is transmitted between wild and domestic animals, often enough to prevent divergent evolution of isolated populations of the parasite. NC-deerl oocysts were administered to a calf that developed a high antibody titer, providing evidence that N. caninum from wildlife can infect cattle. In addition, N. caninum antibody seroprevalence was detected in 64/164 (39%) free-ranging gray wolves (Canis lupus), 12/113 (11%) coyotes (Canis latrans), 50/193 (26%) white-tailed deer, and 8/61 (13%) moose (Alces alces). These data are consistent with a sylvatic transmission cycle of N. caninum between cervids and canids. We speculate that hunting by humans favors the transmission of N. caninum from deer to canids, because deer carcasses are usually eviscerated in the field. Infection of canids in turn increases the risk of transmitting the parasite to domestic livestock.

Differentiating Mexican gray wolf and coyote scats using DNA analysis

Mexican gray wolves (Canis lupus baileyi) are the smallest subspecies of North American gray wolves (Canis lupus), and identification of Mexican wolf scats could be confused with those of sympatric coyotes (Canis latrans). We used DNA analysis (molecular scatology) to differentiate scats (n = 203) of free-ranging Mexican gray wolves and coyotes and compared the results to traditional field methods (i.e., diameter, location, and sign) and odor used for identifying scats of the 2 species. We then used the scats whose species identifications were confirmed with DNA analysis to evaluate discriminant analysis for classifying scats using 3 measurements—diameter, mass, and length. Forty-nine (24%) of the field-collected scats (n = 203) tested provided amplifiable DNA and were determined to comprise 28 scats deposited by Mexican wolves and 21 deposited by coyotes. Scats identified with DNA analysis to the 2 species had a 79% diameter overlap (Mexican wolf 16.3–35.8 mm; coyote 17.4–27.8 mm), and scats ≥28 mm in diameter were Mexican wolf scats. There was a significant difference (t = −2.28; P < 0.05) between diameter means for the 2 species (Mexican wolf r̄x = 26.0 mm; coyote r̄x = 22.8 mm). Of 45 scats that would have been field-identified as deposited by Mexican wolves based on location and odor criteria, DNA analysis indicated that 19 (42%) were deposited by coyotes; of 41 scats that would have been field-identified as deposited by coyotes based on diameter < 30 mm criterion, 20 (49%) were deposited by Mexican wolves. Halfpenny's (1986) suggested diameter criterion for field identification of scats identified 3 of the scats as gray (Urocyon cinereoargenteus) or red fox (Vulpes vulpes; 0% correct), 24 as coyote (62% correct), and 20 as Mexican wolf (75% correct). Discriminant analysis indicated that diameter and mass of scats offered the best results for accurately classifying coyote scats (86%) but provided relatively low accuracy for classifying Mexican wolf scats (65%). Our results suggest that previous diet studies using traditional identification methods may have misrepresented the diets of both the North American gray wolf and the coyote when the 2 species were sympatric. Molecular scatology appears to be a more definitive scat-identification technique than traditional field methods or odor for these canids.

Cardiorespiratory effects of medetomidine-butorphanol, medetomidine-butorphanol-diazepam, and medetomidine-butorphanol-ketamine in captive red wolves (Canis rufus).

Safe, effective, and reversible immobilization protocols are essential for the management of free-ranging red wolves (Canis rufus). Combinations using an alpha2-adrenoceptor agonist and ketamine have been shown to be effective for immobilization but are not reversible and can produce severe hypertension and prolonged or rough recoveries. To minimize hypertension and provide reversibility, 24 red wolves were immobilized using three medetomidine-butorphanol (MB) combinations without the use of ketamine in the initial injection. All wolves were administered medetomidine (0.04 mg/kg i.m.) and butorphanol (0.4 mg/kg i.m.). Seven wolves received no other immobilization agents (MB wolves), nine received diazepam (0.2 mg/kg i.v.) at the time they were instrumented (MBD wolves), and eight received ketamine (1 mg/kg i.v.) 30 min after instrumentation (MBK30 wolves). Physiologic parameters were monitored during immobilization. The heart rate was similar among the three groups for the first 30 min, and marked bradycardia was noted in one wolf from each group. Hypertension was observed initially in all three groups but was resolved within 10-30 min. The MBK30 wolves had significant elevations in heart rate and transient hypertension after intravenous ketamine administration. Most wolves had mild to moderate metabolic acidemia. Immobilizing drugs were antagonized in all wolves with atipamezole (0.2 mg/kg i.m.) and naloxone (0.02 mg/kg i.m.). The medetomidine-butorphanol-diazepam wolves were also given flumazenil (0.04 mg/kg i.v.). All wolves were standing within 12 min and were fully recovered within 17 min. Medetomamine-butorphanol and MBD combinations provided effective and reversible immobilization of red wolves without the sustained hypertension associated with the use of alpha2-adrenoceptor agonist-ketamine combinations. Delaying the administration of ketamine reduced its hypertensive effects.

Antibody response to rabies vaccination in captive and free-ranging wolves (Canis lupus).

Fourteen captive and five free-ranging Minnesota gray wolves (Canis lupus) were tested for the presence of rabies virus neutralizing antibodies (RVNA) after vaccination with an inactivated canine rabies vaccine. Blood was collected from all wolves prior to vaccination and at 1 mo postvaccination (PV) and from all captive and three wild wolves at 3 mo PV. In addition, one free-ranging wolf was sampled at 4 mo PV, and two free-ranging wolves were sampled at 6 mo PV. All wolves were seronegative prior to vaccination. RVNA were detected in 14 (100%) captive wolves and in four of five (80%) free-ranging wolves. The geometric mean titer of the captive wolves at 1 mo PV was significantly higher (P = 0.023) than in the free-ranging wolves. Five of 13 (38.5%) captive wolves and none of the three (0%) free-ranging wolves had measurable RVNA at 3 mo PV. No measurable RVNA were detected in the serum samples collected from the free-ranging wolves at 4 and 6 mo PV. These results should be interpreted with caution because of the small number of free-ranging wolves tested. Further research is needed to properly assess immune function and antibody response to vaccination in captive wolves in comparison with their free-ranging counterparts.

Electrocardiographic consequences of a peripatetic lifestyle in gray wolves ( Canis lupus)

Cardiac chamber enlargement and hypertrophy are normal physiologic responses to repetitive endurance exercise activity in human beings and domestic dogs. Whether similar changes occur in wild animals as a consequence of increased activity is unknown. We found that free-ranging gray wolves ( Canis lupus, n=11), the archetypical endurance athlete, have electrocardiographic evidence of cardiac chamber enlargement and hypertrophy relative to sedentary captive gray wolves ( n=20), as demonstrated by significant increases in QRS duration, QT interval, and QT interval corrected for heart rate, a tendency towards increased Q, R, and S wave voltages in all leads, and a significant decrease in heart rate. We conclude that exercise activity level and therefore lifestyle affects physiologic variables in wild animals. An immediate consequence of this finding is that physiologic measurements obtained from a captive wild-animal population with reduced exercise activity level may not accurately reflect the normal physiologic state for free-ranging members of the same species.

Activity patterns of gray wolves housed in small vs. large enclosures

Free-ranging gray wolves (Canis lupus) generally inhabit large home ranges, yet they are housed in a variety of restricted spaces when in captivity. There is continual debate as to whether space restrictions alter a wolf's behavior. The purpose of these studies was to remotely measure and then compare the amount and frequency of activity of gray wolves housed in small, artificial enclosures vs. large, more natural enclosures. Test animals comprised three adult wolves housed in kennels and three and four wolves housed in separate natural enclosures. Kenneled wolves had 2.8 m2 of surface area per wolf, and wolves in natural enclosures had 466.6 m2 (South Pack) and 349.9 m2 (North Pack) per wolf. Wolves were fitted with radiotelemetry collars containing activity sensors. Activity data were recorded every 20 min for 57 continuous hr. The amount of activity for each wolf was calculated using areas under the curve (AUCs), and the frequency of activity was analyzed by spectral analysis. There was no difference (P ≥ 0.22) in AUCs between kenneled wolves (1.399 ± 0.214 x 105 radians) and South Pack wolves (1.564 ± 0.139 X 105 radians) or North Pack wolves (1.617 ± 0.192 x 105 radians). All three groups had similar peak spectral values at frequencies that were close to daily cycles (i.e., ω = 0.12–0.17 cycles per unit time). Peaks in coherence near the dominant spectral frequency were most significant between the natural enclosures and the least significant between the kenneled wolves and the South Pack wolves. Based on these criteria of activity and under these circumstances, enclosure size appeared to have no effect on wolf activity. However, small sample sizes and variation in the data do not make these results definitive. © 1996 Wiley-Liss, Inc.

Parasitism in Captive and Reintroduced Red Wolves

Fecal examinations revealed that at least 10 of 21 (48%) captive red wolves (Canis rufus) and eight of 12 (67%) free-ranging red wolves were infected with intestinal parasites. No captive wolves and only one of seven reintroduced wolves had dirofilariasis. Ticks were collected from 10 of 21 (48%) captive wolves and nine of 12 (75%) free-ranging animals. Ivermectin administered at a dosage of 50 micrograms/kg of estimated body weight every 30 to 60 days apparently prevented or ameliorated parasitism in red wolves.

Immobilization of Gray Wolves with a Combination of Tiletamine Hydrochloride and Zolazepam Hydrochloride

We immobilized 51 free-ranging gray wolves (Canis lupus) with a combination of tiletamine hydrochloride and zolazepam hydrochloride. Effective initial dose 400 mg (x=10.4±0.6 [SE] mg/kg of body mass). Mean induction and recovery times were 7.2±1.4 minutes and 144±35 minutes, respectively. We did not not observe adverse effects

Effects of Feeding and Fasting on Wolf Blood and Urine Characteristics

Feeding and fasting trials were conducted with 2 groups (A and B) of 4 gray wolves (Canis lupus) each during January 1980. The groups were fed for 9 days and fasted for 10 days in a cross-over design. Blood and urine samples and weight data were collected every 2-3 days during each trial. Hemoglobin (Hb) concentrations, red blood cell (RBC) counts, and hematocrits (HCT) were elevated in both groups during fasting. White blood cell (WBC) counts, serum urea nitrogen (SUN), triiodothyronine (T3), and insulin concentrations decreased during fasting in Groups A and B. Mean corpuscular hemoglobin concentration (MCHC), serum cholesterol, triglyceride, and iron (Fe) concentrations were diminished in fasted Group A wolves compared to fed Group B. Creatine phosphokinase (CPK) concentrations were elevated in fed Group A wolves. Serum creatinine (C) concentrations were reduced in both groups during feeding. Urinary urea:creatinine (U:C), potassium: creatinine (K:C), and sodium:creatinine (Na:C, pooled Group A and B data) ratios decreased in fasted wolves. Differences were not found between fed and fasted wolves for mean corpuscular volume (MCV), serum cortisol, glucose, calcium (Ca), bilirubin, serum glutamate-oxaloacetate transaminase (SGOT), serum glutamate-pyruvate transaminase (SGPT), alkaline phosphatase, and luteinizing hormone (LH) concentrations, total iron binding capacity (TIBC), and urinary calcium: creatinine (Ca:C) ratios. Analysis of multiple blood or urine samples collected from free-ranging wolves would be useful in enabling researchers and managers to identify the nutritional status and general health of wolves over time. J. WILDL. MANAGE. 51(1):1-10 Examination of the physiological and nutritional status of wild animals via blood and urine chemistries has become widespread. A common starting point for such investigations is to establish baseline values for each species. Year-round values for several blood characteristics have been described for a colony of captive adult gray wolves (Seal and Mech 1983) fed ad libitum. However, wild wolves often live a feast-or-famine existence, so conceivably, their blood values may vary considerably depending on how recently and how much they have eaten. The excreted quantities of metabolic products in urine also might vary. Thus, it is important to compare values of blood and urine constituents between fed and fasted wolves. The objective of this study was to determine the influence of feeding dynamics on blood and urine characteristics of these animals. We appreciate the financial support of the Res. Serv., Veterans Adm.; the U.S. Fish and Wildl. Serv.; the Special Proj. Found. Minneapolis Big Game Club; and the logistical support of the Minn. Dep. Nat. Resour. We also thank M. F. Seal for record keeping and sample preparation, M. D. Lewis, N. Manning, and M. K. Twite for laboratory assays, and L. Glaser and T. Pierzina for assisting with the animal care and handling.