Waterfowl toxicology: a review.

Waterfowl populations may serve as sentinel species for natural and anthropogenic toxicologic problems in the environment. Unfortunately, many toxins cause nonspecific clinical signs, acute mortality, and subtle or no pathologic changes, making toxicologic investigations extremely difficult. The purpose of this article is to review important waterfowl toxins, including heavy metals, pesticides, botulism, mycotoxins, algal toxins, and petroleum oil. When applicable, clinical signs, diagnosis, pathologic findings, and treatment are discussed. Although most of the information in the literature is based on wild waterfowl populations or experimental toxicologic investigations, the information is also applicable to captive waterfowl populations.     

云南泸沽湖省级自然保护区越冬水鸟群落组成及相关性分析

2016年9月—2019年3月,采用样点法在水鸟的南迁期(8—10月)、越冬期(11月—次年1月)、北迁期(2—3月)对云南省泸沽湖省级自然保护区迁徙水鸟进行监测。共记录水鸟7目10科38种,其中有国家二级重点保护野生鸟类3种、云南省省级重点保护野生鸟类1种。研究期内,保护区内越冬水鸟优势种累计记录10种,分别为赤麻鸭(Tadorna ferruginea)、绿头鸭(Anas platyrhynchos)、赤颈鸭(Mareca penelope)、罗纹鸭(M.falcata)、赤膀鸭(M.strepera)、赤嘴潜鸭(Netta rufina)、凤头潜鸭(Aythya fuligula)、红头潜鸭(A.ferina)、白骨顶(Fulica atra)和红嘴鸥(Chroicocephalus ridibundus)。2016—2019年月变化中,水鸟数量峰值都出现在越冬期,最大数量为14 296只;水鸟物种数峰值亦都出现于越冬期,共记录物种数38种。对8种雁形目(Anseriformes)优势种数量随时间变化的种间相关性检验的结果显示,8种雁形目中有14对为显著正相关,其中10对为极显著...     

Sarcocystis infections in Georgia swine

Tissues from 168 mature sows obtained at slaughter in northern and southern Georgia were examined for infection with Sarcocystis spp. Digestion techniques revealed zoites in 28 (16.5%) sows. Infected meat was fed to laboratory-reared dogs, cats, raccoons (Procyon lotor), and opossums (Didelphis marsupialis). Dogs and raccoons shed sporocysts (8.3 mum X 11.2 mum) 12 to 14 days after infection. Cats and opossums were refractory to infection. Sarcocystis-free pigs were infected with 50,000 sporocysts of swine-dog origin. Tissues from laboratory-infected swine were fed to dogs and raccoons. Both species shed sporocysts 14 days later. This is the 1st time in which a definitive host has been demonstrated for species of Sarcocystis occurring in North American swine. The raccoon constitutes a new definitive host for S suicanis Erber 1977. In contrast to previously reported low prevalences of Sarcocystis infections in swine, the relatively high prevalence reported here indicates that S suicanis may be of importance to swine producers in Georgia.     

New techniques to measure blood cholinesterase activity in domesticated animals.

A macromethod and a semimicromethod were developed to measure erythrocyte acetylcholinesterase activity in cattle, sheep, goats, horses, dogs, and swine, and to measure plasma cholinesterase activity in horses, dogs, and swine. Comparison of the 2 methods with erythrocytes of sheep, cattle, goats, and horses indicated both methods gave similar results. They can be done in a shorter time and are more sensitive than Michel's method. Normal deltapH values per minutes, with standard deviations for blood cholinesterase activity of animals of different ages, sexes, breeds, and species, were: 0.76 +/- 0.12/30; 0.65 +/- 0.10/15; 0.69 +/- 0.19/45; 0.78 +/- 0.11/45; 0.63 +/- 0.11/45; and 0.71 +/- 0.06/25 for sheep, cattle, goats, horses, dogs, and swine erythrocyte acetylcholinesterase, respectively; and 0.66 +/- 0.18/20; 0.67 +/- 0.20/30, and 0.46 +/- 0.05/60 for horses, dogs, and swine plasma cholinesterase, respectively. It was shown that either the chloride or the iodide salt of acetylcholine can be used as the enzyme substrate. tin blood samples stored at 5 C for 24 hours, there was no significant change of the enzymatic activity.     

Host cell specific activity of RTX toxins from haemolytic Actinobacillus equuli and Actinobacillus suis

We assessed and compared host cell specificity of the haemolytic and cytotoxic activity of the RTX toxins from Actinobacillus equuli, an equine pathogen, and Actinobacillus suis, which is pathogenic for pigs. The two bacterial species are closely related, phenotypically as well as phylogenetically, sharing the same 16S rRNA gene sequence. Both species contain specific protein toxins from the family of pore-forming RTX toxins, however, the two species differ in their RTX toxin profiles. Haemolytic A. equuli contains the operon for the Aqx toxin, whereas A. suis harbours genes for ApxI and ApxII. We tested the toxic activity of the corresponding proteins on erythrocytes as well as on lymphocytes isolated from horse and pig blood. The strength of the haemolytic activity for each of the toxins was independent of the origin of erythrocytes. When testing cytotoxic activity, the Aqx protein showed a higher toxic effect for horse lymphocytes than for porcine lymphocytes. On the other hand, ApxI and ApxII showed a strong cytotoxic effect on porcine lymphocytes and a reduced toxicity for horse lymphocytes; the toxicity of ApxII was generally much lower than ApxI. Our results indicate a host species specificity of the toxic activity of RTX toxins Aqx of A. equuli and ApxI and ApxII of A. suis.     

Antimicrobial resistance and resistance gene determinants in clinical Escherichia coli from different animal species in Switzerland

Antimicrobial susceptibility testing was performed on a total of 581 clinical Escherichia coli isolates from diarrhea and edema disease in pigs, from acute mastitis in dairy cattle, from urinary tract infections in dogs and cats, and from septicemia in laying hens collected in Switzerland between 1999 and 2001. Among the 16 antimicrobial agents tested, resistance was most frequent for sulfonamides, tetracycline, and streptomycin. Isolates from swine presented significantly more resistance than those from the other animal species. The distribution of the resistance determinants for sulfonamides, tetracycline, and streptomycin was assessed by hybridization and PCR in resistant isolates. Significant differences in the distribution of resistance determinants for tetracycline (tetA, tetB) and sulfonamides (sulII) were observed between the isolates from swine and those from the other species. Resistance to sulfonamides could not be explained by known resistance mechanisms in more than a quarter of the sulfonamide-resistant and sulfonamide-intermediate isolates from swine, dogs and cats. This finding suggests that one or several new resistance mechanisms for sulfonamides may be widespread among E. coli isolates from these animal species. The integrase gene (intI) from class I integrons was detected in a large proportion of resistant isolates in association with the sulI and aadA genes, thus demonstrating the importance of integrons in the epidemiology of resistance in clinical E. coli isolates from animals.     

Mycotoxin research in the Hungarian Central Veterinary Institute

Mycotoxin research conducted in the Hungarian Central Veterinary Institute is reviewed briefly. The effect of zearalenone was studied by experiments in several animal species (cattle, pig, sheep, chicken, goose, duck, guinea fowl, fish) and in cell cultures in vitro. The chicken (Gallus domesticus) has proved to be resistant to the toxin. In the susceptible species zearalenone causes the most severe damage to the sexual organs. The metabolism of zearalenone, T-2 toxin and diacetoxyscirpenol was also studied. These toxins are resistant to physicochemical factors but are easily transformed in biologically active environment. The acute toxicity study of trichothecene toxins is described along with morphological changes, with particular respect to those of the lymphoid and myeloid organs. Trichothecene toxins impair the natural defence mechanism of the organism and result in the manifestation of different diseases (swine dysentery, caecal coccidiosis). Deoxynivalenol contamination of the feeds, first of all of wheat, is common in Hungary. Its effect on pig fattening was investigated in a field trial. The toxins of different storehouse moulds were also examined.     

Studies on a canine intestinal spirochete. I. Its isolation, cultivation and ultrastructure.

The microscopic examination of colonic scrapings from 12 of 18 normal dogs revealed the presence of a spirochete. From two such dogs a spirochete was isolated and successfully cultured. Although similar in outward appearance to the porcine spirochete of swine dysentery the canine spirochete possessed ultrastructural properties which distinguished it from the porcine agent. This canine agent is thought to constitute a separate species and should not be confused with the agent associated with swine dysentery.     

Influenza viruses and paramyxoviruses in ducks in the Atlantic flyway, 1977-1983, including an H5N2 isolate related to the virulent chicken virus

From 1977 to 1983, waterfowl migrating along the Atlantic flyway were annually monitored for orthomyxoviruses and paramyxoviruses in an area in central New York State. A total of 168 influenza isolates were obtained from 1,430 waterfowl. Twenty-four combinations of hemagglutinin and neuraminidase subtypes were detected, with as many as 12 found in a single year. One combination, an H5N2 isolate in 1982, was closely related to the virulent chicken virus that appeared in Pennsylvania in 1983. The prevalence of influenza varied greatly among the common waterfowl species: mallards 42%, black ducks 30%, blue-winged teal 11%, wood ducks 2%, and Canada geese 0%. A total of 89 paramyxoviruses were also from these waterfowl. In contrast to findings with influenza virus, the prevalence of paramyxoviruses did not differ significantly among the duck species. Serotype 1 (Newcastle disease virus) was predominant; three other serotypes were also identified. These findings indicated that ducks in the Atlantic flyway continually harbor influenza viruses and paramyxoviruses. The viruses may be a source of infection for other species.     

Viruses of waterfowl

Viral disease can cause substantial mortality in wild populations of ducks as well as domesticated geese and ducks. Migrating and captive waterfowl play a role in the dynamics and epidemiology of some viruses that also infect humans, such as influenza virus and West Nile virus. Crowded farm conditions favor the transmission of infectious disease agents among birds. Disease transmission is further facilitated by the comingling of wild anatids with nonmigratory resident waterfowl flocks in zoological parks or on farms. The following article will emphasize the most important viral diseases of waterfowl and briefly cover the newer diseases of suspected viral etiology in this group of birds. As viral detection and identification techniques become more and more sophisticated, and as the study of wildlife diseases increases, new viruses will be discovered and new diseases will be encountered. More research into the viral diseases of waterfowl is needed; the implementation of the latest techniques in molecular epidemiology in addition to the “gold standard” techniques such as virus isolation and histopathology, will yield insight into how viruses move from species to species and from region to region.     

Staphylococcus pseudintermedius exfoliative toxin EXI selectively digests canine desmoglein 1 and causes subcorneal clefts in canine epidermis

Staphylococcal exfoliative toxins are known to digest desmoglein (Dsg) 1, a desmosomal cell–cell adhesion molecule, thus causing intraepidermal splitting in human bullous impetigo, staphylococcal scalded skin syndrome and swine exudative epidermitis. Recently, a novel exfoliative toxin gene (exi), whose sequence shares significant homology with previously identified exfoliative toxins, was isolated from Staphylococcus pseudintermedius. Little is known about the pathogenic involvement of this toxin in canine pustular diseases such as impetigo. The aim of this study was to determine whether EXI, the product of the exi gene, digests canine Dsg1 and causes intraepidermal splitting in canine skin. An exi gene was isolated from chromosomal DNA of an S. pseudintermedius strain obtained from a pustule of a dog with impetigo, and was used to produce a recombinant EXI by Escherichia coli expression. When purified recombinant EXI was injected intradermally into normal dogs, it caused the development of vesicles or erosions with superficial epidermal splitting. In addition, the EXI abolished immunofluorescence for Dsg1, but not for Dsg3, at the injection sites. Moreover, the EXI directly degraded baculovirus‐secreted recombinant extracellular domains of canine Dsg1, but not that of canine Dsg3, in vitro. The EXI also degraded mouse Dsg1α and swine Dsg1, but not human Dsg1, mouse Dsg1β and Dsg1γ. Conversely, recombinant SIET, previously designated as S. intermedius exfoliative toxin, did not cause intraepidermal splitting or degradation of any Dsgs. These findings indicate that EXI has a proteolytic activity that digests canine Dsg1, and this characteristic might be involved in the pathogenesis of intraepidermal splitting in canine impetigo.     

Waterfowl parasites

Waterfowl, whether free-living or in captivity, are hosts to a wide variety of internal and external parasites. With few exceptions, the significance of most parasitic infections is unknown, due, in part, to the fact that mixed parasitic infections are the rule rather than the exception. Therefore, effects of any one parasite species must be made in light of the other parasites, diseases, or stressors (eg, malnutrition) that may be present. Furthermore, the pathogenicity of a parasite may differ among species of birds as well as different populations of the same species. Experimental assessment of the effects of some parasites have been attempted using the mallard duck as the model; however, in light of species differences, the applicability of such studies to other species of waterfowl is unclear. Of the several hundred parasites that are present, nasal leeches, Leucocytozoon simondi, certain species of coccidia, some nematodes, the trematode Sphaeridiotrema globulus, cestodes in the genus Gastrotaenia, and some acanthocephalans have been associated with morbidity and/or mortality in captive or wild waterfowl. Detection of many parasitic infections can be accomplished through traditional diagnostic techniques (eg, fecal flotation, blood smears); however, the presence of parasites does not automatically equate with the presence of disease. Control and treatment measures are few, especially for free-ranging waterfowl. However, excellent sanitation can help combat many parasites in captive situations.     

哈尔滨地区猪旋毛虫对猪,犬的感染性试验

用消化法所得的猪旋毛虫蚴分别接种猪，犬。结果表明，猪旋毛虫对猪，犬的感染性存在着明显差异，在猪的繁殖力指数为１１７．０４，而在犬为３０．６０，说明哈尔滨地区猪旋毛虫档地旋毛形线虫；     

Waterfowl rehabilitation: A primer for veterinarians

Ducks, geese, and swans are an easily recognized group of birds. There are approximately 50 native species in North America, all of which are considered migratory. Despite being a legally hunted family of birds, native waterfowl are federally protected, and there are federal laws associated with their rehabilitation, disposition of nonreleasable animals, and disposal of carcasses. In the United States, there are several nonnative species found with increasing frequency that many don’t realize are feral exotics. There also are state laws dealing with owning exotic waterfowl and prohibition of their release. Native waterfowl occupy a variety of wet habitats, have unique feeding requirements, have specific enclosure and substrate needs, and should be treated by someone with expertise to ensure recovery sufficient for return to the wild. If a practitioner is going to accept wild waterfowl as patients, it is important they know the laws, identify species, understand species natural history, and learn about associated common problems. This article discusses legalities, basic husbandry issues, common presentations, and basic veterinary/rehabilitation matters of waterfowl commonly found by the public. It also covers some common problems seen with feral exotic waterfowl as well.     

Morphine-isoflurane interaction in dogs, swine and Rhesus monkeys

In monkeys, dogs and swine (six each) we tested the reduction of the isoflurane MAC (minimal alveolar concentration) produced by 2 mg-kg^-1 morphine intravenously (i-v.) and the concurrent effect on Pco₂ with spontaneous ventilation. MAC fell to a minimum of 55% of control at 53 min in monkeys, 50% at 38 min in dogs and 13% at 33 min in swine. Paco₂ rose at constant MAC with morphine to 55–60 mmHg, but did not fall over the next several hours despite the decline of plasma morphine concentration, and the resulting needed rise in isoflurane concentration to keep the anaesthesia depth at 1 MAC. After isoflurane concentration had returned to pre-morphine control levels, naloxone immediately reduced Paco₂ to or below control level. Morphine pharmacokinetics in the three species studied conformed to a two-compartment model.     

Malignant hyperthermia susceptibility: cardiac histomorphometry of dogs and young and market-weight swine.

The defect causing malignant hyperthermia has been proposed to involve cardiac as well as skeletal muscle. We tested the hypothesis that histomorphometric parameters for ventricular wall from malignant hyperthermia-susceptible swine and dogs were abnormal. Hearts were obtained from: mature dogs, age- and weight-matched young swine (89 +/- 15 days, 30 +/- 3 kg); and market-weight swine (102 +/- 10 kg). Using light microscopy, estimates were made for muscle nuclear dimensions and the volume-fraction of nuclei, sarcoplasm, blood vessels, and interstitial space. Cardiac maturation in both MH and normal swine was accompanied by decreased myocyte volume-fraction due to decreased nuclear volume-fraction and increased interstitial space volume-fraction. Sarcoplasm and vasculature volume-fraction were unchanged after maturation. Nuclear volume-fraction was slightly greater (p less than 0.05) in the right ventricle than the left for malignant hyperthermia and normal swine. Myocyte nuclear dimensions were generally similar among animals. Dogs and the oldest group of swine were not significantly different. Myocytes of all swine contained multiple nuclei, closely spaced in rows of 2 to 12. In contrast, most myocytes of mature dogs apparently contained one or two nuclei. Histomorphometric values were not significantly different between normal and malignant hyperthermia young swine and dogs. However, within the market-weight swine, volume-fraction for malignant hyperthermia myocytes and myocyte nuclei was decreased and interstitial space was increased compared to normal.(ABSTRACT TRUNCATED AT 250 WORDS)     

Corrosion potential of steel bird shot in dogs.

Each year many dogs are accidentally or purposely wounded with shotguns. When lead pellets were used exclusively in the past, clinical problems from chronically embedded shot seldom developed except for rare cases of lead toxicosis. However, because expended lead shot ingested unintentionally by waterfowl and other avian species is fatal, the US Fish and Wildlife Service mandated exclusive use of steel shot for waterfowl hunting beginning in 1991. To discover the effects of implanted steel shot in a biological system, in vitro and in vivo studies were performed. Severe surface corrosion was evident when steel shot was placed in physiologic saline solution and sterile canine plasma. Eight laboratory dogs were surgically implanted with sterile steel shot in various superficial locations for intervals of 2 to 26 weeks. Corrosion of implants and tissue inflammation was observed in all biopsy specimens examined. It has been shown that steel shot embedded in tissues will corrode and result in a severe inflammatory response. If the accompanying inflammation is complicated by bacterial contamination, foreign body reactions resulting in infected, draining tracts could develop. Veterinarians and dog owners should be aware that treatment and prognosis for wounds caused by steel shot may differ from those for similar wounds caused by lead shot.     

Amanita muscaria toxicosis in two dogs

Objective: To report the manifestations, history, and pathophysiologic basis of disease in 2 dogs with Amanita muscaria toxicosis. Case summaries: Two dogs were evaluated for an acute onset of gastroenteritis and seizures. A. muscaria toxicosis was suspected in each dog after confirmation of environmental exposure and visualization of ingested mushrooms in vomitus. The diagnosis was confirmed following identification of toxic Amanita metabolites in the urine and serum of each dog. Administration of supportive and symptomatic therapies resulted in the complete recovery of each animal. Unique information provided: Ingestion of the mushroom, A. muscaria, by dogs can result in acute gastrointestinal distress that precedes a potentially life‐threatening central neurologic syndrome characterized by seizures, tremors, and somnolence. Central nervous system dysfunction results primarily from the actions of ibotenic acid and its decarboxylation product, muscimol, which are analogues of the neurotransmitters glutamate and γ‐aminobutyric acid (GABA), respectively. Identification of these toxins in the urine and serum of affected dogs using high‐performance liquid chromatography (HPLC) provides a definitive diagnosis.