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The aim of this study was to describe the epidemiological, clinical, and pathological findings of two outbreaks of gastrointestinal nematode infections in beef cattle kept under an inadequate sanitary protocol. An outbreak of trichostrongylosis occurred in Amambai, Mato Grosso do Sul (MS), from May to July 2016. The herd consisted of 3,000 Nellore cows, and of these, fifteen died after showing emaciation and diarrhea and remaining in recumbency. At necropsy, the abomasum showed edema in the folds, white, raised areas, multifocal to coalescent, and small ulcers. Histopathology showed larvae compatible with trichostrongylid nematodes were present inside the abomasum glands. Trichostrongylus axei was identify in the abomasum. The hemonchosis outbreak began in October 2018, in a breeding and finishing property in Santa Rita do Pardo, MS. Of 4,000 cattle aged 8 to 18 months, 673 became ill and 117 died. Clinical signs were emaciation, weakness, dehydration, submandibular edema, and soft stools. At necropsy, large numbers of nematodes were found in the abomasum; they were morphologically classified as Haemonchus placei. Both outbreaks were caused by failures in the parasite control protocol. However, in Outbreak I, frost and immune stress caused by lack of food may have contributed to the deaths. In Outbreak I, the main failure in the devermination protocol was the use of anthelmintics without carrying out an efficacy test. In Outbreak II, there was no parasite control protocol in the rearing and finishing property, and in the breeding property, there was resistance to the anthelmintic used (ivermectin). The two outbreaks highlight the importance of gastrointestinal nematode control protocols in cattle and demonstrate that infections by T. axei and H. placei can be lethal for this species. RESUMO: O objetivo deste trabalho foi descrever os achados epidemiológicos, clínicos e patológicos de dois surtos de verminose em bovinos de corte mantidos sob protocolo sanitário inadequado. Um surto de tricostrongilose ocorreu em Amambai, Mato Grosso do Sul (MS), de maio a julho de 2016. O rebanho de cria era composto por 3.000 vacas Nelore, das quais, quinze vacas adultas morreram após apresentarem emagrecimento, diarreia e permanecerem em decúbito. Na necropsia, o abomaso apresentava edema das pregas, áreas brancacentas, elevadas, multifocais a coalescentes e pequenas úlceras. Na histopatologia, larvas compatíveis com nematódeos tricostrongilídeos estavam presentes no interior das glândulas do abomaso. A recuperação de helmintos do abomaso demonstrou que Trichostrongylus axei foi o principal agente etiológico. O surto de hemoncose iniciou-se em outubro de 2018, em uma propriedade de recria e terminação em Santa Rita do Pardo, MS. Do total de 4 mil bovinos com 8 a 18 meses, 673 adoeceram e 117 morreram. Os sinais clínicos foram emagrecimento, fraqueza, desidratação, edema submandibular e fezes pastosas. Na necropsia, havia grande quantidade de nematódeos no abomaso, que foram classificados morfologicamente como Haemonchus placei. Ambos os surtos foram causados por falhas no protocolo de controle parasitário, porém, no Surto I, geadas e estresse imunológico causado pela falta de alimento podem ter contribuído para as mortes. No Surto I, a principal falha no protocolo de desverminação foi o uso de anti-helmínticos sem a realização de teste de eficácia. No Surto II, não havia protocolo de controle parasitário na propriedade de recria e terminação, e na propriedade de cria, havia resistência ao anti-helmíntico utilizado (ivermectina). Os dois surtos ressaltam a importância dos protocolos de controle de nematódeos gastrintestinais em bovinos e demonstram que infecções por T. axei e H. placei podem ser letais para esta espécie.

The equine pinworm could become an increasingly common problem, as there are reports of failure in the control of this parasite. The aim of this study was to evaluate the effects of ivermectin (IVM) and IVM combined with pyrantel pamoate (PYR). Thirteen parasitological positive equines were treated with oral IVM (200 µg/kg) and therapeutic efficacy, clinical recovery and the egg reappearance period (ERP) were evaluated. In cases for which ERP was shorter than the pre-patent period (PPP), a second treatment was performed with IVM (200 µg/kg) + PYR (6.6 mg/kg), followed by the same evaluation criteria described above. Therapeutic efficacy was 100% with IVM + PYR and 53.84% with IVM. The mean ERP was shorter than the PPP with both formulations, 77.55 days with IVM + PYR and 50 days with IVM. The presence of egg mass was always associated with a least one clinical sign. The reduction in the number of clinical signs per animal from Day 0 to Day 30 was greater in equines treated with IVM + PYR compared to those treated with IVM alone. The animals treated with IVM were 4.5-fold more likely to present clinical signs 30 days after treatment than those treated with IVM+PYR. A negative correlation was found between ERP and the number of clinical signs at 30 days in the animals treated with IVM. This clinical and parasitological evaluation demonstrated that the combination of IVM+PYR was more effective than IVM alone to control Oxyuris equi.