Confirmation of methomyl poisoning in a cat by LC-MS
Felipe Reggeti, Nick Schrier, Amanda Mansz
A 5-mo-old indoor/outdoor male DSH cat was found dead outside the owner’s house. The cat was healthy and had not received any medications or vaccines. The carcass was submitted to the AHL for postmortem examination. The body was in good condition, with adequate muscle mass and good hair coat. The stomach was filled with 40 mL of soft brown, slurry-like feed material admixed with a few grains of rice and flecks of black-brown dried leaves. The feed material within the fundus of the stomach, towards the pylorus, was discoloured aqua blue/green (Fig. 1). The remaining PM exam was unremarkable. Gastric contents were submitted to the toxicology section, and “Methomyl” was identified by LC-MS.
Methomyl (S-methyl-N-[(methylcarbamyl)oxythioacetamide]) is a broad-spectrum carbamate insecticide/acaricide. It is highly toxic to humans and animals (oral LD50 rats: 12-48 mg/kg) with anticholinesterase activity causing neurologic signs. In acute toxicity, death may result from paralysis of respiratory muscles and/or airway constriction. The product is commonly used to control flies; however, cases of misuse to intentionally kill wildlife have been reported in North America. Methomyl products typically contain the co-ingredient muscamone [(Z)-9-tricosene], a pheromone found in dipteran flies. In addition, caffeine-containing fluids are frequently added to the bait for malicious poisoning. Identification of these substances may provide clues for toxicologic investigation in some cases. The AHL offers a comprehensive GC/MS-LC-MS method for identification of over 400 pesticides - see LabNote 59 https://www.uoguelph.ca/ahl/ahl-labnote-59-gcms-lcms-multi-residue-method , as well as other potentially toxic compounds, including tremorgenic mycotoxins, strychnine, barbiturates and others; however, it cannot identify all possible toxins. Suitable samples include liver, GI contents and suspect material. Please submit frozen. AHL
Figure 1. Stomach contents of a cat poisoned with methomyl. Note the blue-green discoloration of the stomach contents.
Mycoplasma haemofelis infection in a DSH cat
Kris Ruotsalo, Janet Beeler-Marfisi
A 2-y-old, castrated male, domestic shorthaired cat was presented with a 2-d history of lethargy and pallor. Serum biochemistry and CBC revealed marked hyperbilirubinemia 139 µmol/L (reference interval [RI] 0-3 µmol/L), marked mildly regenerative anemia, hematocrit 0.10 L/L (RI 0.28-0.49 L/L), and hemoglobin 31 g/L (RI 93-153 g/L).
Blood smear examination confirmed marked anemia (Fig. 1); hemotropic mycoplasmas appear as small (0.3-0.8 µm), blue-staining cocci, rings, or rods that are usually attached to erythrocytes (partially buried in on the cell surface), or occasionally noted free within the slide backgrounds. PCR is needed for specific identification. PCR testing at the AHL confirmed the presence of M. haemofelis; M. haemominutum and M. turicensis were negative. M. haemofelis is the most pathogenic of the 3 hemotropic mycoplasmas, the least prevalent, one of the most common infectious causes of regenerative anemia in cats, and one of the causative agents of immune-mediated hemolytic anemia in cats.
A follow up CBC was taken 11 d after initial presentation and a course of treatment; hematocrit was 0.31 L/L and hemoglobin was 97 g/L, with no organisms identified on the peripheral blood smear. AHL
Figure 1. Mycoplasma haemofelis infection. Note marked anemia, RBC ghosts (intravascular hemolysis), abundant epicellular coccoid-to-signet-ring shaped organisms at the periphery of the RBCs and free in the slide background.
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