We examined age and nutritional related changes in the distribution and size of gut associated lymphoid tissues in the intestinal tract of cotton rats (Sigmodon hispidus). Peyer's patches in the small intestine are prominent, ranging from four to 13, and increase in size (surface area) with age. The average Peyer's patch in the adult cotton rat measured 23.9 mm². Lymphoid tissue in the cecum was primarily limited to a large aggregate located in the vermiform appendix, which increased in size with age. Age related changes in the number of visible lymphoid follicles in the large intestine were highly significant, increasing from 24.8 in juveniles to 45.1 in adults. Weights of dissectable Peyer's patch tissue in animals consuming a low protein diet were significantly lower in juveniles and greater in subadults compared to those on high protein diets. Relative weights of Peyer's patch tissue averaged 84 to 95% more in low protein-fed animals than in the group on the high quality protein diet. Our results suggest that peripheral lymphoid tissues in wild cotton rats are more resistant to protein deficiencies than other tissues in the body and could be a useful index for assessing nutritional status.

From 1986 to 1989, sera from wild turkeys (Meleagris gallopavo), including three subspecies (M. gallopavo intermedia, M. gallopavo merriami and M. gallopavo mexicana) trapped in six western states were tested for antibody to Mycoplasma gallisepticum (MG) (n = 724), M. synoviae (MS) (n = 461) and M. meleagridis (MM) (n = 354) using the rapid plate agglutination (RPA) assay. Subsamples of these sera were also evaluated using the hemagglutination inhibition (HI) assay for antibody to MG (n = 664) and MS (n = 403). Attempts were made to isolate mycoplasmas by swabbing the trachea and cloaca of 190 live wild turkeys and from various tissues (sinus, nasal turbinates, trachea, lung, ovaries and oviduct) from 76 turkeys at necropsy. Isolates were identified using an immunobinding assay. Seroprevalence of MG, MS and MM in the RPA test was highly variable among years and geographic sites, ranging from 0 to 85%, 0 to 87%, and 0 to 83%, respectively, for each mycoplasma species. Of the 724 wild turkey sera tested, 200 (28%) were positive using the RPA assay, while only 20 (3%) of 664 sera tested using the HI assay were positive (at a titer >/= 1.80) for antibody to MG. Of the 461 sera tested 178 (39%) were RPA positive for MS, whereas none of the 403 samples tested by HI were positive for MS. Antibody to MM was detected in 72 (20%) of 354 turkey sera tested by RPA. Mycoplasmas were cultured from 81 (30%) of 266 wild turkeys, including 48 that were sampled live and 33 that were examined by necropsy. Mycoplasmas were isolated from every population in which culture was attempted. M. gallopavonis (MGP) was isolated from 37 (46%) of 81 birds which yielded mycoplasma, representing seven of 12 populations sampled. MG was isolated from lower respiratory tissues of one Rio Grande wild turkey trapped in Texas. M. synoviae was isolated from five of 16 Merriam's wild turkeys trapped in Arizona. Sera of birds from which MG or MS was isolated were positive to the respective antigen in the RPA test, but were negative by the HI assay. The RPA test was effective in identifying MG and MS infected turkeys despite lack of confirmation by the HI test. These data suggest that apparently healthy wild turkeys can carry pathogenic mycoplasmas and the currently used field test (RPA) can identify culture positive wild turkeys. Serological screening using the RPA test should be conducted on all wild turkeys prior to relocation.

A serologic survey of the prevalence of morbillivirus antibodies was conducted in a population of harbor seals (Phoca vitulina) from northeastern Scotland, where mortality was comparatively low during the 1988 phocine distemper virus outbreak. None of the 12 seals sampled before the epizootic were seropositive. Thirty-five (52%) of 68 seals sampled after the beginning of the epizootic were seropositive, although there were significant age-related differences in both the number of seropositive individuals and in antibody levels. Marking studies showed that most seropositive seals caught during the peak of the epizootic survived for several months. Thus, the low mortality observed in this population did not appear to result from a lack of contact with the virus.

Diagnostic findings were reviewed on 157 sick or dead gray foxes (Urocyon cinereoar-genteus) from the southeastern United States examined during the period 1972 through 1989. Most foxes (n = 118) originated from Georgia; fewer animals were from Florida, Kentucky, Maryland, Mississippi, North Carolina, South Carolina, Tennessee, Virginia and West Virginia. Etiologic diagnoses included canine distemper (n = 125), congenital absence of guard hairs (n = 7), traumatic injuries (n = 7), rabies (n = 3), suspected toxicoses (n = 3), verminous pneumonia due to Paragonimus kellicotti (n = 1), bacterial septicemia secondary to Dracunculus insignis (n = 1), and tick paralysis (n = 1). Concurrent toxoplasmosis or cryptosporidiosis was noted in six and three foxes with canine distemper, respectively. Only lesion diagnoses were attainable for three foxes, and six cases were classified as undetermined. Canine distemper was diagnosed in 78% of the foxes, was geographically widespread, was detected in 16 of 18 yr, and exhibited a seasonal pattern of occurrence. These facts indicate that canine distemper is more significant as a mortality factor for gray foxes than all other infectious and noninfectious diseases combined.

A 5 yr survey (1985 to 1989) revealed that the prevalence of frog erythrocytic virus (FEV) was significantly higher in juveniles than in adult bullfrogs (Rana catesbeiana) in Algonquin Park, Ontario (Canada). The prevalence of infection in juveniles declined during May and June and increased in early August, persisting until late September. Tadpoles were not infected naturally with FEV, but were susceptible to experimental infection. Experimental data indicate that FEV is neither waterborne, nor transmitted by the oral route, nor by the leech Desserobdella picta. The virus may be transmitted mechanically by the mosquito Culex territans, or the midge Forcipomyia (Lasiohelea) fairfaxensis. Nine percent recapture of marked uninfected frogs versus 4% recapture of infected animals suggests that FEV contributes to mortality of juvenile bullfrogs. Infected erythrocytes were transformed from ellipsoidal to spheroidal cells, some of which contained flattened elongate, trapezoidal inclusions. There was no evidence of denatured hemoglobin or significant change in the hemoglobin content of infected cells. Anemia recorded in heavily infected animals was not attributable to an increased osmotic fragility of infected erythrocytes.

Livers from 4,501 deer mice (Peromyscus maniculatus) collected from a weedy habitat in northeastern California during 48 consecutive monthly samplings were examined microscopically for Taenia taeniaeformis larva. Although there were pronounced seasonal fluctuations in host density, there were no significant annual or season-related differences in cestode intensities in adult deer mice. There were no significant differences in prevalences associated with sex of the host, nor were there significant changes in level of reproduction noted between infected and non-infected hosts. There were, however, significant differences in prevalences between young (1.2%) and adult (4.2%) hosts. Plausible mechanisms for this age-related difference in prevalence rates include (1) differential susceptibility due to the activity pattern of adult mice and/or (2) passive immunity in neonates as a result of colostrum- and/or transplacentally-transferred immunoglobulins and (3) capture of subadult animals before they had completed the period of highest susceptibility to T. taeniaeformis. Density of larvae per mouse liver was determined during a 21 mo consecutive period. The intensity of T. taeniaeformis larvae was not significantly different between the sexes of the adult mice. The larval stage showed an overdispersion pattern within the adult population. These results suggest that determinations of T. taeniaeformis abundances can be accurately made, at least in this P. maniculatus population, at any time of the year provided adjustment is made for the relative age structure of the host population.

To determine raccoon (Procyon lotor) susceptibility and serum neutralizing antibody response to a skunk salivary gland rabies virus, raccoons were inoculated with a rabies virus isolated from a naturally-infected striped skunk (Mephitis mephitis). Raccoons were divided into four groups of three animals each. A dilution of the rabies virus suspension, 10²⁴, 10³⁴, or 10⁴⁸, mouse intracerebral lethal dose₅₀ (MICLD₅₀), was administered into the masseter muscles of each animal. Three negative control animals received only diluent. Saliva and sera were collected on post-inoculation days 35, 63 and 92 for virus isolation and determination of serum neutralizing antibody titer. All animals survived the 92 day observation period and none exhibited the behavioral changes classically associated with clinical rabies virus infections. Rabies virus was not detected in the saliva of any raccoon and two of the three animals receiving the highest inoculum developed serum neutralizing antibodies (SNA). On day 92, a challenge suspension of New York City/Georgia (NYC/GA) strain rabies virus in fox salivary glands (10³² MICLD₅₀) was administered to all 12 raccoons. All animals succumbed to rabies virus except the two animals that had earlier developed SNA. The results of this study provided evidence about the susceptibility of raccoons to a skunk rabies virus and demonstrated that exposed raccoons could survive for at least 92 days following exposure. Furthermore, animals developing SNA under such circumstances were capable of with-standing challenge with rabies virus that was fatal for seronegative raccoons.

After the first recorded outbreak of rabies in the Svalbard Islands (Norway) in 1980, brain tissue from 817 trapped arctic foxes (Alopex lagopus) was tested for rabies by a direct fluorescent antibody test. During the same period (1980 to 1990), 29 arctic foxes, 23 polar bears (Ursus maritimus), 19 reindeer (Rangifer tarandus) and five ringed seals (Phoca hispida) were also tested using the same technique. These animals had either been found dead, killed because of abnormal behavior or were apparently healthy when they were collected. Rabies virus antigen was not detected in any of the trapped foxes. Rabies was confirmed in two foxes in 1981, two foxes and one reindeer in 1987, and in one fox in 1990. The presence of rabies in the Svalbard archipelago probably resulted from immigration over the sea ice of an infected host.

A model baiting system suitable for the delivery of an oral rabies vaccine to free-ranging raccoons (Procyon lotor) was developed and tested on barrier islands in South Carolina (USA). Features of barrier island physiography and ecology were studied relative to selective bait deployment and site biosecurity. Capture-mark-recapture data were obtained from 228 raccoons. Raccoon density estimates, using a modified census assessment technique, were one raccoon per 1.8 to 2.7 ha. Mean (±SE) and range home area estimates of radio-collared raccoons were 84 (±15.6) ha (27 to 176 ha) by a minimum convex polygon method and 138 (±22.8) ha (43 to 241 ha), by a harmonic mean transformation method. Habitat utilization determinations of radio-collared raccoons were conducted to identify study areas to potentially maximize selectivity of bait towards raccoons and to reduce the absolute number of baits deployed. Island raccoons showed a habitat preference for maritime forest, maritime shrub and marsh areas. Additionally, there was no evidence of inter-island or mainland exchange of ear-tagged or radio-collared raccoons. A disease and mortality survey was conducted to identify baseline pathology and incidental lesions in the target raccoon population, prior to actual vaccination initiation. Thirty-eight percent of 30 clinically suspect raccoons sampled had intracytoplasmic eosinophilic inclusions diagnostic of canine distemper; no other lesions suggestive of viral etiologies were found. Serological surveys for raccoon poxvirus and rabies virus antibodies were negative. Antibody titers to canine adenovirus 1 and 2 indicated a moderate level of exposure (approximately 10 to 16%) in the raccoon population. Overall, 93 to 100% of placebo baits were consistently disturbed by 7 days post-bait deployment, and bait acceptance rates by raccoons ranged from 49 to 85%, by using a modular systems approach to select the optimum combination of bait attractant, biomarker, matrix, density, and distribution. These results suggest that a large proportion (up to 85%) of a free-ranging island raccoon population can be selectively and safely targeted, marked and monitored utilizing a proposed oral bait delivery system for recombinant or other rabies vaccines.

Sixty-two percent of 26 wild caught Gouldian finches (Erythrura gouldiae) were infected with Sternostoma tracheacolum, a parasitic rhinonyssid mite. The intensity of infection was higher in adult finches than juveniles, and higher in juvenile females than juvenile males. Histopathological investigation of wild Gouldian Finches revealed bronchopneumonia and air sacculitis associated with mite infection. Although this mite may not have contributed to the decline of Gouldian finch populations in the wild during the past 20 yr, it may be suppressing the return of the finch to its former status.

Oral inoculation of prairie voles, Microtus ochrogaster, with coccidian sporocysts isolated from the feces of a red-tailed hawk, Buteo jamaicensis, in Kansas, USA, resulted in formation of Frenkelia microti (Apicomplexa: Sarcocystidae) tissue cysts in the brains of the voles. Five additional isolates of morphologically similar sporocysts collected from red-tailed hawks or other Buteo spp. in Kansas failed to result in detectable infections in rodents. These results are the first to verify that red-tailed hawks are natural definitive hosts in North America for F. microti.

Resting metabolic rates, weight gains and hematologic profiles of six newborn, captive white-tailed deer (Odocoileus virginianus) fawns (four females, two males) were determined during the first 3 mo of life. Estimated mean daily weight gain of fawns was 0.2 kg. The regression equation for metabolic rate was: Metabolic rate (kcal/kg^0.75/day) = 56.1 1.3 (age in days), r = 0.65, P < 0.001). Regression equations were also used to relate age to red blood cell count (RBC), hemoglobin concentration (Hb), packed cell volume, white blood cell count, mean corpuscular volume, mean corpuscular hemoglobin concentration (MCHC), and mean corpuscular hemoglobin. The age relationships of Hb, MCHC, and smaller RBC's were indicative of an increasing and more efficient oxygen-carrying and exchange capacity to fulfill the increasing metabolic demands for oxygen associated with increasing body size.

Six fallow deer (Dama dama) fawns died after receiving 25 to 150 infective larvae of Parelaphostrongylus tenuis. Fawns given higher doses usually died sooner (6 to 23 days) than those given lower doses (54 to 67 days). Early deaths were associated with severe acute peritonitis resulting from perforation of the intestinal wall; later deaths were associated with paralysis and inability to rise. Numerous adult P. tenuis were found within neural tissues of the brain and spinal cord in the three fawns with paralysis. One white-tailed deer (Odocoileus virginianus) exposed to infective larvae from the same source survived infection without exhibiting clinical signs and began passing larvae in feces 88 days post-exposure. At the doses used in this study, meningeal worm caused fatal infections in fallow deer. Results are compared to published observations of fallow deer naturally-infected with P. tenuis.

Blood was collected from captive cheetah cubs (Acinonyx jubatus) from the ages of 4 to 12 wk and monitored for the decline in maternally derived antibodies to feline panleu-kopenia, herpes and calici viruses. A steady decrease was seen in most of the cubs. Antibody responses to inactivated and/or modified live virus (MLV) vaccine also were measured. The strongest responses were seen post vaccination with MLV vaccine only.

Serum samples and choanal cleft swabs were collected from livetrapped and hunter killed wild turkeys (Meleagris gallopavo) from Martin and Bertie counties, North Carolina (USA). Sera were tested for antibodies to Mycoplasma gallisepticum, Mycoplasma synoviae and Mycoplasma meleagridis by hemagglutination inhibition (HI). Sera from 33% (five of 15) of livetrapped turkeys were positive for antibodies to M. gallisepticum by HI, and all were negative for antibodies to M. synoviae and M. meleagridis. Choanal cleft swabs from 22 livetrapped and five hunter killed wild turkeys cultured in Frey's broth medium resulted in 23 mycoplasma isolations. Using direct immunofluorescence, 74% (17/23) were M. gallopavonis, and 26% (six of 23) were unidentified; no isolate was identified as M. gallisepticum, M. synoviae or M. meleagridis.

Renibacterium salmoninarum antigen was detected in the kidney of migrating chum salmon (Oncorhynchus keta) using the indirect dot blot assay and indirect fluorescent antibody test. The adult chum salmon had migrated into a bay in which cultured coho salmon infected with R. salmoninarum were present. Antigen was detected in 5% of the chum salmon although they did not have clinical signs of bacterial kidney disease (BKD). This report describes the first case of R. salmoninarum antigen detection among wild chum salmon populations in eastern Asia.

A juvenile raccoon (Procyon lotor) was found moribund near Fort Collins, Colorado (USA). Upon examination, the raccoon was dehydrated, had a mucopurulent oculonasal discharge and diarrhea, and was euthanized. Postmortem examination revealed emaciation, severe fibrinous gastroenteritis and a small, firm liver. Histopathological findings included blunting of villi, infiltration of lamina propria with neutrophils and plasma cells, and mild bronchopneumonia. Cryptosporidium sp. was demonstrated on intestinal villi and coronavirus and parvovirus were identified in feces. Fluorescent antibody test for rabies was negative and no evidence of canine distemper was found.

Sarcocysts were found in the tongue, diaphragm, heart, intestinal tunica muscularis, and skeletal muscle of bobcats (Felis rufus floridanus) collected in Florida (USA). The tongue was found to be the best indicator tissue for sarcocysts (P < 0.005). Thirty of 60 bobcats screened were found to contain sarcocysts in at least one of the muscle tissues examined. Of the positive bobcats, 28 of 28 tongues contained sarcocysts, while only 10 of 27 (37%), and 8 of 26 (31%) contained sarcocysts in the diaphragm or cardiac muscle, respectively. Although immune suppression has been suggested as a possible reason for formation of sarcocysts in some carnivores, no such correlation was evident in the bobcats. Comparisons of prey species taken by the panther and bobcat, and overlap of geographical range by the two species leave questions as to the source of infection, and the species of Sarcocystis that is infecting both felids.

Pneumocystis carinii (PC) is an opportunistic pathogen which causes clinical disease in immunocompromised hosts. Three different staining protocols were employed to detect this organism in lung samples of corticosteroid treated voles in order to discover a suitable method for large-scale screening. The procedures employed were: Grocotts methenamine silver (GMS)-stained paraffin sections, toluidine blue O-stained impression smears, and methenamine-silver-stained frozen sections. GMS-stained paraffin sections were relatively easy to interpret and gave more positive results than the other methods. It seemed to be the satisfactory method for large-scale population analyses. An unexpected result was that methylprednisolone treatment did not induce in voles a similarly fatal pneumocystosis infection as occurred in rats. All infections found in voles were mild. This might be due to species-dependent differences in metabolizing methylprednisolone.

In North America, the role of wild ruminants in the epidemiology of anaplasmosis has not been clearly defined. Such information is particularly meager in regard to bighorn sheep. We report the susceptibility of two Rocky Mountain bighorn sheep (Ovis canadensis canadensis) to experimental infection with a well characterized field isolate of Anaplasma ovis obtained from domestic sheep in Idaho. Both bighorn sheep developed infection resulting in severe clinical disease, with relatively high parasitemias, icterus and anemia. One animal required tetracycline therapy and responded well to treatment, while the other recovered uneventfully without treatment. Both bighorn sheep were spleen-intact, a condition that in A. ovis-exposed domestic sheep typically is associated with mild infection. The results indicate that bighorn sheep may be adversely affected if exposed to the organism in nature.

Gastrointestinal helminths including two species of cestodes (Taenia omissa and T. ovis krabbei) and three species of nematodes (Toxocara cati, Cylicospirura subequalis and Ollulanus tricuspis) are reported from two free-ranging cougars (Felis concolor) in Washington (USA). Ollulanus tricuspis is reported for the first time from cougars and represents the first occurrence of this parasite in a sylvatic felid from North America.

A species of syngamid nematode belonging to the genus Syngamus was found in the respiratory tract (terminal trachea to bronchi) of tundra voles (Microtus oeconomus) collected on St. Lawrence Island, Alaska (USA). Its prevalence in June 1989 was >29% (12 of 41 male voles and seven of 24 females) in the village of Savoonga, while no nematodes were found from 41 voles collected in the village of Gambell. Lesions included dilatation of parasitized respiratory ducts and peribronchial and perivascular cuffing by lymphoid cells, mainly plasma cells, in parasitized lobes. Morphologically, this syngamid species differed from S. microtinae reported previously from the same host species as well as from other syngamids known from avian hosts.

Twenty-three livetrapped and two trapper-caught river otters (Lutra canadensis) from northeastern Pennsylvania (USA) were examined for ectoparasites immediately after their captures during 1981 to 1985. Ectoparasites were collected from both trapper-caught otters, but from only one livetrapped otter. One species of tick (Ixodes cookei) and one flea (Oropsylla arctomys) were collected.

Infection with blow fly larvae (Protocalliphora braueri) had no effect on sage thrasher (Oreoscoptes montanus) nestling weight or size at fledging nor on mean fledging age. However, the combination of cold, wet weather and parasite infection did significantly reduce nestling survival and the percent young fledged.

Sera from 324 birds collected in an Ockelbo virus disease endemic area in central Sweden were examined for the presence of specific antibodies to Ockelbo virus by a plaque reduction neutralization test. Birds examined belonged to the orders Anseriformes (n = 207), Galliformes (n = 66) and Passeriformes (n = 51). Ockelbo virus neutralizing antibodies were detected in 26 (8%) of the specimens, including species from each of the three orders tested. Specific antibodies found in caged birds and in 6- to 10-week-old birds suggested local transmission. The highest antibody prevalence (27%, 14/51) was observed in the Passeriformes in which 5 of 9 species tested contained antibodies. The high antibody prevalence in passeriforms and the very large population of this group in relation to other avian groups in Sweden gives them a high potential as amplification hosts for Ockelbo virus.

Oronasal squamous cell carcinoma was diagnosed in an adult African hedgehog (Erinaceidae albiventris). Clinically, the carcinoma presented as a firm right maxillary swelling with deviation of the nose to the left. The carcinoma was attached to the hard palate and protruded into the oral cavity. At necropsy, the carcinoma appeared centered in the right maxillary sinus, and had replaced the maxilla and extended into the nasal cavity. Metastatic foci were not found.

A typical chondrosarcoma is reported from the nictitating membrane of a great white heron (Ardea herodius occidentalis). This is the first report of a neoplasm in a free flying ciconiiform, and was the only one found in a survey of 957 carcasses from Florida.

An emaciated wild turkey (Meleagris gallopavo) exhibiting neurologic signs was found on Ossabaw Island, Chatham County, Georgia (USA) on 11 April 1989. The neurologic abnormalities observed included ataxia, drooping wings, head tremors, torticollis, and circling. At necropsy, discrete yellowish-white nodules, varying in size from 2 to 5 mm, were present in the spleen. White nodular lesions approximately 2 mm in diameter were observed beneath the mucosal surface of the distal esophagus. Histopathologic examination of the splenic nodules disclosed large numbers of primitive lymphoreticular cells with leptochromatic nuclei and abundant, slightly basophilic cytoplasms. The mitotic index in these cells was moderate to high. Similar neoplastic cells composed the masses observed in the esophagus. Multifocal, mild perivascular cuffing with mononuclear cells was found in the lumbar spinal cord, brain, and brain stem. Reticuloendotheliosis virus, subtype 3, was isolated from samples of the spleen and liver.