Marina L. Brash

Arthritis and Osteomyelitis Associated with Enterococcus Cecorum Infection in Broiler and Broiler Breeder Chickens in Ontario, Canada

In August 2008, an Ontario broiler chicken flock experienced an outbreak of lameness in 4-week-old birds, with morbidity reaching 7% by day 3. Necropsy examination and histopathology revealed arthritis of the hock, stifle, and coxofemoral joints, and femoral and vertebral osteomyelitis. Enterococcus cecorum was isolated from the lesions and identified by 16S ribosomal RNA sequencing. In October 2008, a second case of E. cecorum osteomyelitis involved a flock of 9-week-old broiler breeder chickens, with 2% of the male birds showing reluctance to walk. Necropsy examination revealed osteomyelitis and abscessation of the body of the caudal thoracic vertebra in affected birds, with impingement on the overlying spinal cord.

Diversity of Enterococcus cecorum from chickens.

Enterococcus cecorum is a normal inhabitant of the intestine of birds and other vertebrates. It has recently emerged in Canada and other countries as an important cause of arthritis and osteomyelitis in chickens. The objectives of this study were to assess if this emergence was caused by a particular clone of E. cecorum and to assess the antimicrobial susceptibility of this organism. One hundred and thirteen E. cecorum isolates from infections in Canadian chickens (cases) and from the ceca of control chickens from Canada and Belgium were examined. Isolates were identified using biochemical tests and, for a number of them, identification was confirmed by partial 16S rRNA gene sequencing. Case and control isolates were typed by pulsed-field gel electrophoresis and tested for antimicrobial susceptibility using the broth microdilution method. Cecal isolates from control birds were genetically very diverse but the vast majority of those from cases belonged to a single major clonal lineage. Reduced susceptibility was widespread for tetracycline, bacitracin, and erythromycin. Isolates from cases were generally less susceptible to antimicrobial agents than isolates from control birds.

Genotyping of Canadian field strains of infectious bursal disease virus

For this retrospective study, infectious bursal disease virus (IBDV) was detected in 134 bursal samples that originated from flocks with conditions such as airsacculitis, tracheitis, pneumonia, septicaemia, inclusion body hepatitis, coccidiosis, and/or a history of production problems without overt clinical symptoms. Samples were from seven Canadian provinces: Ontario, Quebec, Manitoba, British Columbia, Nova Scotia, Alberta, and Newfoundland and Labrador. Viral RNA was identified in bursae with moderate to severe and acute to chronic bursal damage. The ages of the flocks from which samples were collected ranged from 3 to 63 days. Following reverse transcriptase-polymerase chain reaction the nucleotide sequence of the VP2 hypervariable region was determined and compared with sequences available in GenBank. The most common Canadian IBDV field strains were North-American variant viruses. Forty-four viruses were highly related (97.5% to 100.0%) to the US IBDV strain NC171. Moreover, 16 field viruses whose VP2 sequences were 99.2% to 100% identical to the South African 05SA8 IBDV strain appeared closely related to the NC171 group. Delaware E-related field viruses, 98.3% to 100.0% identical to the prototype virus, were identified in 33 samples. Thirty-four Canadian IBDVs showed the highest identity, 94.2% to 98.3%, to US IBDV strain 586. Five samples contained vaccine-related viruses, while two field strains showed the best match to Del A (United States) and IBDV strains SP_04_02 (Spain). Very virulent IBDVs were not detected in Canada.

Genotyping of infectious bronchitis viruses identified in Canada between 2000 and 2013

Infectious bronchitis virus (IBV) was detected in 185 samples originating from chicken flocks of various commodity groups in Canada. Flocks with clinical signs such as respiratory challenge, sudden death, egg production problems, or nephropathogenic conditions, and randomly selected flocks sampled at slaughter as part of an Ontario broiler surveillance project, were included. Most samples were from Ontario and Québec; however, a small number from British Columbia, Nova Scotia, and Newfoundland and Labrador were also analysed. The nucleotide sequence of the spike (S) protein gene was compared with sequences available in GenBank. Based on their S gene sequence similarities, Canadian IBVs could be divided into nine genotypes belonging to four groups: Canadian variant virus, strain Qu_mv; the classic, vaccine-like viruses, Connecticut and Massachusetts; US variant-like virus strains, California 1734/04, California 99, CU_82792, Pennsylvania 1220/98 and Pennsylvania Wolg/98; and non-Canadian, non-US virus, strain 4/91. Based on the field situation, the effectiveness of current vaccination practices mostly based on Massachusetts and Connecticut-type vaccines appeared generally satisfactory for minimizing the damage due to infection with Canadian variant and US variant-like viruses. However, the recent outbreaks of severe respiratory disease and production problems in Ontario chicken flocks related to the incursion of IBV strain 4/91 were not prevented by standard vaccination protocols. It appears that IBV strain 4/91 has now become endemic in Ontario and the need for 4/91-type vaccines must be evaluated.

The complete mitochondrial genome sequence of an Isospora sp. (Eimeriidae, Eucoccidiorida, Coccidiasina, Apicomplexa) causing systemic coccidiosis in domestic Canaries (Serinus canaria Linn.)

Abstract We report a complete mitochondrial genome sequence for an Isospora sp. causing systemic coccidiosis in canaries, Serinus canaria. The A + T rich (65.2%) genome was 6216 bp in length and possessed 3 protein-coding genes, (COI; COIII and CytB), 19 LSU and 14 SSU rDNA fragments, including 1 newly identified putative LSU fragment. Arrangement of coding regions was identical to that of available Eimeria sp. mt genomes and start codon usage for protein-coding genes was conventional. The similar mitochondrial genome sequences and structures of Isospora and Eimeria species confirm the close relationship between these eimeriid genera of apicomplexan parasites.

Isolation and Identification of Duck Adenovirus 1 in Ducklings with Proliferative Tracheitis in Ontario

Abstract Increased mortality was reported in two flocks of Muscovy ducklings from two consecutive hatches originating from the same breeder flock. Coughing, dyspnea, and gasping were observed in some ducklings between 6 and 11 days of age. Opaque white plugs of exudate were seen in the tracheas with some ducklings having multiple tracheal plugs. Tracheal and bronchial epithelium was hyperplastic and superficial epithelial cells contained eosinophilic intranuclear viral inclusions. Virus particles compatible with adenovirus morphology were observed in tracheal epithelial cells by electron microscopy and in the supernatant from cell cultures inoculated with filtered tracheal homogenates. The isolated virus was genetically indistinguishable from duck adenovirus 1 (DAdV-1). Our report confirms for the first time the presence of DAdV-1 in Canada and also reports for the first time adenovirus-associated respiratory disease in ducklings and supports previous findings that some DAdV-1 can be pathogenic even in waterfowl.

On-farm biosecurity practices and causes of preweaning mortality in Canadian commercial mink kits

BackgroundMink are an important animal commodity group in Canada and excessive kit mortality represents a significant loss to production. National biosecurity standards have been developed for Canadian mink farms, but it is unclear how well these standards have been implemented as there are no studies correlating management practices of mink producers with causes of death in mink kits. To that end, we surveyed Ontario mink producers on their biosecurity and management practices and conducted almost 5660 post mortem examinations on found-dead, preweaned kits to characterize mink farm biosecurity practices and causes of death in preweaned kits.ResultsWe found that very few biosecurity and management practices were uniformly used by producers, despite good awareness of appropriate practices. Use of personal protective equipment was implemented by fewer than 50% of respondents, while control of mink shed access, disinfection of feed containers after use, and use of a rodent control program were the only practices implemented by greater than 70% of respondents. Only 18% of producers reported regular use of antimicrobials in feed or water, although 91% stated they used antimicrobials for treatment of bacterial diseases on a regular basis. On post mortem examination, no gross abnormalities were noted in 71% of the kits, 45% were thought to be stillborn or aborted, 27% had some form of abnormal fluid distribution in the body, and 2% had a congenital malformation. A subset of 69 gastrointestinal tract samples was submitted for bacterial culture, of which 45 samples yielded sufficient growth. Most interesting was the identification of Salmonella enterica serovar Heidelberg in 11% of samples.ConclusionsThe results of this study will provide a benchmark for Canadian mink producers and their veterinarians, defining the areas to which greater attention should be given to ensure more rigorous biosecurity practices are in place. Ultimately, these improvements in practices may contribute to increased mink production and animal well-being.

Identifying dead-on-arrivals (DOA) at shackling in a slaughter line gas stunning system for end-of-lay hens: Part I - Hock flexion resistance and wing position

SUMMARY This study of end‐of‐lay fowl characterized the development of rigor mortis over time after euthanasia by testing the force required to flex a hock joint and by evaluating wing position as a test to differentiate euthanized birds from stunned birds. Using a force gauge, it was demonstrated that measurable resistance to hock flexion to the point of activation of the perch reflex develops rapidly after death and consistently increases over time, plateauing at 90 min. Based on a minimum detection threshold of 300 gram‐force (gf) for hock stiffness, birds that developed rigor quickly, in the 50th percentile and higher, were detectable by 5 min postmortem, and all birds in the study population were detectable by 21 min postmortem. In addition, the sensitivity and specificity of wing position to differentiate dead birds from stunned birds was high (87.5 and 100%, respectively). We conclude that the development of palpable hock joint stiffness is sufficiently rapid to be useful as a means of differentiating between hens unconscious after CO2 gas stunning from hens that died during transport or lairage. Wing position can be used as a secondary assessment as the hen is lifted to the shackle line, such that the presence of wings held tight to the body would identify the hen as a DOA.

Identifying dead-on-arrivals (DOA) at shackling in a slaughter line gas stunning system for end-of-lay hens: Part II - Proof of concept for detecting simulated change in hock flexion resistance

SUMMARY In this study, the simulated hock flexion resistance at which employees could consistently differentiate a stunned bird from a recently dead end‐of‐lay hen was evaluated. A mechanical apparatus was used with individually weighted levers, ranging in resistance from 66 to 485 gram‐force (gf), in a random order. A reference lever was weighted at 120 gf, which is similar to that of stunned birds measured immediately after gas stunning. Each employee (n = 15) lifted each lever to an approximately horizontal plane and designated it as having less resistance or similar resistance to the reference lever (light) or greater resistance than the reference lever (heavy). Dominant and non‐dominant hands were tested independently. For resistance of up to 300 gf, there was a significant (P ≤ 0.05) increasing curvilinear trend in the proportion of employees who considered the lever to be heavy, and a significant decreasing curvilinear trend in the proportion who considered the lever to be light. At greater than 300 gf, close to 100% of employees gave the designation heavy, and there was no significant (P > 0.05) change with any further increases in weight. It was concluded that employees could reliably detect hock flexion resistances of ≥ 300 gf as larger in magnitude than 120 gf.

White Chick Syndrome Associated with Chicken Astrovirus in Ontario, Canada

SUMMARY Sixty-four cases of white chick syndrome (WCS) in broiler breeders producing affected progeny were reported from seven hatcheries in Ontario, Canada, between 2009 and 2016, with 43 of those originating from two hatcheries owned by a single company. WCS cases were identified by the presence of typical chicks in the hatchery that were generally weak with pale to white down, enlarged abdomens, and occasionally brown wiry fluff on the dorsum of the neck. Affected embryos and chicks had characteristic gross and histologic liver lesions, and livers were positive for chicken astrovirus (CAstV) RNA by real-time reverse transcriptase PCR. Affected broiler breeder flocks experienced egg production drops of 0% to 21% and hatchability drops of 0% to 68.4%. The amino acid sequence of the region encoding the capsid gene of WCS viruses demonstrated all Ontario CAstV to be in Group B, Subgroup Bii.