is 4-methylimidazole. Reference. 1. Morgan SE, Edwards WC. Bovine bonkers: New terminology for an old problem. A review of toxicity problems associated ...
CROSS-CANADA DISEASE REPORT RAPPORT DES MALADIES DIAGNOSTIOUEES AU CANADA,
Ontario Recent gentamicin-resistant turkey Salmonella isolates S ince mid-April 1988, the VLSB Guelph laboratory has identified seven isolates of gentamicinresistant Salmonella sp. from turkeys. These isolates have had mean inhibitory concentration values in excess of 16 jig/mL. These samples were received through two different avian veterinary practices and from at least four different premises. Of the seven, two were identified as S. heidelberg, two were S. senftenberg, one was S. agona, one was S. bredeney, and one has not yet been typed. Two patterns of resistance were observed. The more common hierarchal resistance, which included the additional less active aminoglycosides kanamycin and neomycin, was seen as well as one that included kanamycin but not neomycin. This suggests that at least two genetic mechanisms of resistance are involved. Gentamicinresistance was also observed in other enteric organisms
isolated concurrently with these samples. Gentamicin-resistant turkey Salmonella isolates have been reported previously from California. These isolates were shown to contain plasmids responsible for the resistance. Two of the Ontario isolates have been shown to possess plasmids, but the mechanism of resistance, either chromosomal or plasmid-mediated, has not been clearly identified. Gentamicin is widely used to inject newly-hatched turkey poults to prevent Salmonella and other infections. This routine use has presumably selected for resistant strains. Gentamicin is generally considered routinely effective against enterics including Salmonella. If nonselective widespread prophylactic use of this drug in animal husbandry were to make such strains increasingly prevalent, there could be a major impact.
John A. Lynch, Veterinary Laboratory Services, Ontario Ministry of Agriculture and Food, P.O. Box 3612, Guelph, Ontario NIH 6R8
Saskatchewan Ammoniated forage poisoning of cattle ("Bovine Bonkers") Dead calves were submitted for postmortem examination from two separate outbreaks in March and May of 1988. In each instance, the owners observed the calves (and in some cases the cows also) "going crazy" - running at speed into fences for periods lasting about 15 minutes - then returning to normality for a time. The ages of the affected calves ranged from 10 days to 8 weeks. Green feed treated with 3%o anhydrous ammonia was incriminated in both outbreaks, and removal of this material resulted in rapid recovery of sick cattle. Postmortem findings in the calves were negative or related to physical injuries resulting from collisions with fences, etc. Histopathological examination of
brain tissue revealed perivascular and intramyelinic edema. The chemical which is currently under suspicion as the major neurotoxic principle in ammoniated feeds is 4-methylimidazole. Reference 1. Morgan SE, Edwards WC. Bovine bonkers: New terminology for an old problem. A review of toxicity problems associated with ammoniated feeds. Vet Hum Toxicol 1986; 28: 16-18.
Jim Orr and Tom Hutchinson, Department of Veterinary Pathology, Western College of Veterinary Medicine, University of Saskatchewan, Saskatoon, Saskatchewan S7N OWO
Alberta Mastitis associated with suspected Nocardia sp. During the first six months of 1988, we have identified Gram-positive bacilli with branching, beaded filaments in numerous mastitic milk samples. These samples were collected from 32 cows, present on 14 dairy farms. The last time we identified this organism was once in 1985. Based on morphology and 846
growth characteristics, it was ildentitiled as suspect Nocardia sp. The classification of this organism, which has recently also been identified in British Columbia and Ontario, is presently under review. These cases were first recognized from a Gram-stained smear of the mastitic milk. Thereafter, they were cultured on blood agar (507o sheep blood, tryptic soy agar base) and incubated aerobically at 35°C. There was no growth after 48 hours, but by 72 h there were white, Can Vet J Volume 29, October 1988
pinpoint colonies. These became dry, rough, and irregular with yellow-orange pigmentation after five days of incubation. In eight cases, the bacilli were not observed with Gram-stained smear of mastitic milks, but the organism grew on blood agar. In affected cows the mastitis occurred immediately or up to three months after freshening, and was characterized by sudden onset and markedly swollen glands, which remained hard. Most affected quarters ended up with a firm mass in the lower portion of the gland and/or dried up. In one cow, which was sent to slaughter, the mastitis was characterized histologically by a multifocal to diffuse, pyogranulomatous inflammation with diffuse fibrosis. Organisms were evident throughout the gland and supramammary lymph node on Grocott's stain. This infection is generally associated with unhygienic procedures during intramammary infusions, teat
dipping, or udder washing. Herd outbreaks have been linked to contaminated products, multi-dose drug vials, and infusion cannulas (1). We found infected cows in clean herds in which individual syringes were used for dry cow and mastitis therapy. Producers need to re-evaluate their udder washing practices, prior to milking, to limit further spread of this organism. Reference 1. Sears PM. Nocardial mastitis in cattle: Diagnosis, treatment, and prevention. Compend Contin Educ 1986; 8: F41-F46.
Matt Schoonderwoerd and Cindy Plante-Jenkins, Alberta Agriculture, Animal Health Division, P.O. Box 8070, Edmonton, Alberta T6H 4P2
British Columbia
Dinoseb toxicity in dairy heifers
An inexperienced farmer, following nonprofessional advice, treated four two-year-old dairy heifers for ringworm by brushing the infected areas with what was thought to be an iodine solution. Approximately 200 mL were applied to the face and neck regions of each of the heifers in the evening of a particularly hot day. The following morning all four animals were found dead. Time of death was estimated to have been approximately four hours after application of the product. An unlabelled 4 L white plastic bottle, containing a dark-reddish-brown, viscous liquid, was presented to the Veterinary Laboratory for identification. Since the farmer's hands were stained with the product, and skin absorption seemed to have occurred in the cattle, there was a good deal of concern regarding the farmer's well being. Quick tests for iodine, nicotine, and strychnine proved negative. To conclusively incriminate the product, a small amount was applied to the skin of a gerbil; it died overight. Further enquiries from the previous occupants of the farm indicated the possibility that the product was "PREMERGE". It was also discovered that all the vegetation in the areas where the cattle had fallen had died. The product was delivered to the pesticide section of the Ministry of Environment's laboratory where it was found to contain approximately 500o dinoseb. Premerge is a pesticide, no longer registered in Canada, that contains dinoseb (2-sec-butyl-4, 6-dinitrophenol), a dinitrophenol compound. Dinoseb is a herbicide, insecticide, and fungicide that was registered for use in orchards as a dormant spray or for blossom thinning, for strawberry, corn, and various legume and flower crops for annual grass and broadleaf weed control, and in potatoes for top kill-
ing. Its use has been abandoned due to potential chronic effects in applicators. Dinoseb has a high acute mammalian toxicity (LD50: oral = 37; dermal = 200 mg/kg body weight). It is absorbed with ease through intact skin and leaves a distinct yellow or orange stain. It is estimated, in this case, that each heifer received a dermal dose of between 200-250 mg active ingredient/kg body weight. Dinitrophenols are reported to increase metabolism by uncoupling cellular phosphorylation. This results in an increased oxygen demand, respiratory and heart rate, and a subsequent increase in body temperature. High environmental temperatures markedly increase the toxicity. Signs of toxicity occur within several hours, and include listlessness, deepened and more rapid respiration, sweating, thirst, oliguria, muscular weakness, prostration, dyspnea, and death, with terminal hyperpyrexia. There is no specific antidote for poisoning by dinitrophenols. This case exemplifies the danger of unlabelled containers. Robert Puls, Veterinary Pathology Laboratory, Ministry of Agriculture and Fisheries, Box 100, Abbotsford, B.C. V2S 4N8
Cross-Canada Disease Report Contributions are welcome and may be sent to: W.D.G. (Bill) Yates Health of Animals Laboratory Agriculture Canada 116 Veterinary Road University of Saskatchewan Campus Saskatoon, Saskatchewan S7N 2R3
:. :.. Erratum. In the article entitled 'Streptococcus pneuoniae type 3 in an Ontario racehorse' (Can Vet J 29: 665-666), we omitted the name of Cantonyles inthe tObleof contents. The publisher apologizes for this unfortunate omission. Can Vet J Volume 29, October 1988
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