Peritonitis caused by intestinal loop rupture due to parasitism by Parascaris equorum in horses - case reportABSTRACT
This report aims to describe a case of equine colic that resulted in the death of a male Thoroughbred colt, caused by intestinal rupture due to high parasitism of Parascaris equorum in Jataí, Goiás. The animal showed intense abdominal pain, but veterinary care was not requested in time, and the animal died before the veterinary team arrived at the property where the animal was located. The necropsy was performed with the aim of discovering the sudden death of the animal, in which free fluid was observed in the abdominal cavity, as well as characteristic of serofibrinous peritonitis and the presence of helminths that were later identified, through their morphological characteristics, as P. equorum. This nematode can cause diarrhea, intestinal obstruction or asymptomatic. In cases of intense parasitism, it can evolve into cases of intestinal rupture followed by peritonitis, a fatal condition in horses. We relate the rupture followed by peritonitis with the high presence of this ascarid. This report demonstrates that the differential diagnosis of acute abdomen with poisonous colic must be considered, highlights the importance of early diagnosis through coproparasitological exams, often neglected, which allow identification of the parasite, correct treatment, and points out the lethality of this parasitism.
Keywords:
acute abdomen; emergency evaluation; foals; obstruction; parascariosis
RESUMO
Este relato tem como objetivo descrever um caso de cólica equina que resultou na morte de um potro macho Puro Sangue Inglês (PSI), causada por ruptura intestinal devido ao alto parasitismo de Parascaris equorum em Jataí, Goiás. O animal apresentou intensa dor abdominal, porém o atendimento veterinário não foi solicitado a tempo, e ele veio a óbito antes da chegada da equipe veterinária à propriedade. Realizou-se necropsia com o objetivo de averiguar a morte súbita do animal, sendo observada a presença de líquido livre na cavidade abdominal, além de características de peritonite serofibrinosa e a presença de helmintos, posteriormente identificados, com base em suas características morfológicas, como P. equorum. Esse ascarídeo pode provocar diarreia, obstrução intestinal ou ser assintomático. Em casos de intenso parasitismo, pode haver evolução para ruptura intestinal, seguida de peritonite, resultando em quadro fatal em equinos. A ruptura seguida de peritonite foi associada à alta carga desse ascarídeo. O presente relato demonstra que o diagnóstico diferencial de abdômen agudo com cólica venenosa deve ser considerado, além de ressaltar a importância do diagnóstico precoce por meio de exames coproparasitológicos, muitas vezes negligenciados, os quais permitem a identificação do parasita e, consequentemente, o tratamento correto, bem como apontam a letalidade desse parasitismo.
Palavras-chave:
abdômen agudo; avaliação de emergência; potros; obstrução; parascariose
INTRODUCTION
Endoparasites are a significant concern for horse breeders, especially in young foals under one year of age. Diarrhea and colic are considered the primary clinical signs of gastrointestinal parasites (Martins et al., 2021) and the colic, a multifactorial syndrome, can be caused by obstruction due to parasitism of Parascaris equorum in foals (Martins, 2019) due to the size of the adult worms, which can reach 10 to 50 cm in length and 4 mm in diameter (Bowman, 2020).
Parascaris equorum is an ascarid with a cosmopolitan distribution and is a significant cause of unthriftiness in young foals. While light intestinal infections can be well-tolerated, moderate infections can cause a loss of appetite in young animals, resulting in poor growth, a dull coat, and lethargy. When there are many larvae, it may cause coughing, fever, and anorexia. After the prepatent period, which is at least ten weeks, the diagnosis can be confirmed through copro-parasitological examinations (Albergaria and Elsheikha, 2025).
Heavy infection of adult worms in the small intestine may cause impaction and perforation, leading to peritonitis (Jones et al., 2020), a potentially life-threatening diseases in horses (Davis, 2003). The classic symptoms are increased production of peritoneal fluid, as well as changes in its morphophysiological characteristics. It typically results in the exudation of lymph, fibrin, inflammatory cells, and the formation of pus (Jones et al., 2020). The prognosis is usually reserved, and depends on ability and agility to diagnosis, avoiding complications (Davis, 2003).
Therefore, we aim to report a case of equine colic that resulted in the death of a male Thoroughbred colt, caused by intestinal rupture followed by peritonitis due to high parasitism of P. equorum in Jataí, Goiás.
ETHICAL ASPECTS
The research was submitted to the Ethics Committee on Animal Use of the Federal University of Jataí, and approved under the number 011/21.
CASE REPORT
In July 2020, veterinary care was requested for a male Thoroughbred colt, approximately two years old, at a stud farm near the city of Jataí, Goiás, Brazil. According to the owner, from the early hours of the previous day, the animal began to show agitation and signs suggesting intense pain, indicating possible colic syndrome.
However, before the veterinary team arrived at the stud farm, the animal died. Therefore, to obtain a diagnostic conclusion, a routine necropsy technique was performed on the species, revealing a large amount of yellow-green serous fluid leaking from the interior of the abdominal cavity (Figure 1A).
The peritoneum was diffuse and moderately hyperemic, as was the serosa of the abdominal viscera. The intestinal loops showed moderate and extensive deposition of fibrinoid material, adhering them to each other (Figure 1B), characterizing diffuse serofibrinous peritonitis.
In addition, long roundworms were observed multifocally, free in the cavity, originating from a discontinuous intestinal segment with leakage of contents. Upon opening the small and large intestines, several specimens of the same parasite were identified, indicating severe parasitemia with consequent rupture of the intestinal loop (Figures 1C and 1D), which justifies the clinical picture described by the owner.
Some specimens and the morphological characteristics of the parasite were compatible with those described in the literature for P. equorum. No other changes that could justify the clinical picture or the death of the animal were observed during the necropsy, leading to the diagnosis of peritonitis due to intestinal rupture due to severe parasitemia for P. equorum.
Necropsy of a foal with peritonitis due to rupture of an intestinal loop. A) Presence of free fluid observed after abdominal incision; B) Reddish peritoneum, with signs of inflammation and the presence of a mucopurulent substance; C) Presence of free Parascaris equorum in the abdomen with bloody and intestinal content; D) Ruptured intestinal loop in a young horse, with the presence of free P.equorum, evidencing thromboembolism due to parasitism.
DISCUSSION
Equine colic syndrome is a painful and potentially fatal condition that can be caused by multiple factors. Fast identification of signs of severe colic is of utmost importance because of the higher chance of the animal surviving (Silva and Travassos, 2021). Veterinary medical care is essential for determining the appropriate intervention measures and severity through clinical and physical examinations, as well as laboratory and imaging tests (Melo and Ferreira, 2024).
The signs of colic presented by the foal are consistent with a retrospective study of 25 young horses with acute small intestinal obstruction associated with Parascaris spp. infection (Cribb et al., 2006), which found that 80% of them demonstrated mild to severe abdominal pain. Another report with the same diagnosis also described clinical signs of acute abdominal pain and anxiety before death (Ryu et al., 2004). Obstruction and subsequent intestinal rupture may occur due to the large parasite load present in infected animals (Tatz et al., 2012), as adult larvae can reach 50 cm in length in the small intestine and occupy a significant portion of the lumen (Bowman, 2020).
Intestinal rupture is a condition with high mortality and can be considered fatal (Tabar and Cruz, 2009). Several causes can contribute to the rupture process, and in this case, it is believed that the main triggering factor was the high parasite load. The large volume of helminths can be responsible for lesions in the intestinal wall, disturbances in peristalsis, and intense distension of the loops. This distension causes rupture, and due to peritoneal contamination with intestinal contents and bacteria, peritonitis and endotoxic shock occur (Davis, 2003). We report a case where rupture occurred after obstruction and torsion, which could have been avoided, first with early detection of parasitism and treatment, or with rapid veterinary care to detect the cause of equine acute abdomen syndrome.
Peritonitis can develop from a single source of bacterial contamination, which rapidly spreads to the entire abdominal cavity through peristalsis, wall contractions, and the diaphragm. The initial damage promotes the release of inflammatory factors, which lead to tissue degradation. In the case of generalized infection, the animal may suffer severe dehydration and hypovolemic shock due to the large volume of fluid and electrolytes within the peritoneal cavity (Davis, 2003) what happened in the reported case and very quickly.
The definitive diagnosis of peritonitis can be made through abdominocentesis, verifying the presence of intestinal contents in the peritoneal fluid. However, in some cases, the abdominal fluid may only show nonspecific inflammatory changes (Tabar and Cruz, 2009). The success of the treatment depends on a rapid and accurate diagnosis, allowing for immediate and aggressive therapy against the disease to be instituted (Davis, 2003). Unlike the reported case, the diagnosis was not established until the necropsy examination. Therefore, the differential diagnosis of acute abdomen from venomous colic should be considered, as we relate the rupture followed by peritonitis with the high presence of P equorum. Taking these aspects into account, along with the poor prognosis for patients with high infestations, it is essential to reinforce parasite control and prevention on farms. Anti-helminthic treatment must be carried out with drugs of proven efficacy and through strategic programs, with intervals previously established by a veterinarian according to the needs of each farm.
CONCLUSIONS
We relate the rupture followed by peritonitis with the high presence of this ascarid. The differential diagnosis of acute abdomen from venomous colic should be considered, as we showed in this report, can be avoided with early diagnosis of parasitism carried out with coproparasitological tests.
ACKNOWLEDGMENTS
We thank The Coordenação de Aperfeiçoamento de Pessoal em Nível Superior, Conselho Nacional Científico e Tecnológico, and Fundação de Amparo à Pesquisa do Estado de Goiás for the fellowship.
REFERENCES
- ALBERGARIA, I.S.; ELSHEIKHA, H. Diagnostic challenges and alternatives for difficult-to-detect equine gastrointestinal parasites. UK Vet. Equine, v.9, p.138-146, 2025.
- BOWMAN, D.D. Georgis’ parasitology for veterinarians 11.ed. Saint Louis: Elsevier Saunders, 2020. 528p.
- CRIBB, N.C.; COTÉ, N.M.; BOURÉ, L.P. et al Acute small intestinal obstruction associated with Parascaris equorum infection in young horses: 25 cases (1985-2004). N.Z. Vet. J., v.54, p.338-343, 2006.
- DAVIS, J.L. Treatment of peritonitis. Vet. Clin. North Am. Equine Pract., v.19, p.765-778, 2003.
- JONES, S.L.; FECTEAU, G.; HULLINGER, P.J. et al Diseases of the alimentary tract. In: SMITH, B.P.; VAN METRE, D.C.; PUSTERLA, N (Eds.). Large animal internal medicine Saint Louis: Mosby Elsevier, 2020. p.702-920.
- MARTINS, A.V.; MOURA, L.C.; MOURA, P.L.M. et al Pesquisa de parasitos gastrointestinais em equinos com enfoque na raça Puro Sangue Inglês mantidos em propriedades de Teresópolis, Rio de Janeiro, Brasil - resultados preliminares. Jopic, v.7, n.1, 2021.
- MARTINS, I.V.F. Parasitologia veterinária 2.ed. Vitória: Edufes, 2019.
- MELO, U.P.; FERREIRA, C. Cólica equina: decidindo a necessidade de intervenção cirúrgica. Braz. J. Anim. Environ. Res., v.7, p.e71375, 2024
- RYU, S.H.; JANG, J.D.; BAK, U.B. et al Gastrointestinal impaction by Parascaris equorum in a Thoroughbred foal in Jeju, Korea. J. Vet. Sci., v.5, p.181-182, 2004.
- SILVA, J.; TRAVASSOS, A.E.V. Cólica equina: revisão de literatura. Diversitas J., v.6, p.1721-1732, 2021.
- TABAR, J.J.; CRUZ, A.M. Cecal rupture in foals - 7 cases (1996-2006). Can. Vet. J., v.50, p.65-70, 2009.
- TATZ, A.J.; SEGEV, G.; STEINMAN, A. et al Surgical treatment for acute small intestinal obstruction caused by Parascaris equorum infection in 15 horses (2002-2011). Equine Vet. J., v.44, suppl.43, p.111-114, 2012.
The research data are available within the article itself.
