Health risks associated with the use of automatic milk feeders in calves

The objective of the present article was to summarize available evidence of the economic benefits and health risks associated with the use of automatic milk feeders (AMFs) in calves. Although AMFs are increasingly used in cattle production, clear evidence of their economic benefits (increased average daily gain, gradual weaning and reduced labor time) for the typical Belgian farm size and management is not available. Especially in smaller farms, where labor time is not a limiting factor, a careful economic consideration should be made. Regarding the association of AMFs with calf disease, studies have only been performed for bovine respiratory disease and confirmed an increased risk. However, since the use of AMFs is strongly related with several other risk factors (group housing at young age, large groups, age difference in a group, continuous system versus all-in/all-out), it is difficult to unequivocally identify the risk associated with AMFs alone. A group size of less than ten calves on a single drinking point, an all-in/alloutb grouping system and a minimum age at introduction to the automat of three weeks are recommended for farms with AMFs. To the authors’ knowledge, no scientific evidence supporting the presumed association of diarrhea and tongue ulcers with AMFs is available to date

Rethinking the role of alpha toxin in Clostridium perfringens-associated enteric diseases : a review on bovine necro-haemorrhagic enteritis

Bovine necro-haemorrhagic enteritis is an economically important disease caused by Clostridium perfringens type A strains. The disease mainly affects calves under intensive rearing conditions and is characterized by sudden death associated with small intestinal haemorrhage, necrosis and mucosal neutrophil infiltration. The common assumption that, when causing intestinal disease, C. perfringens relies upon specific, plasmid-encoded toxins, was recently challenged by the finding that alpha toxin, which is produced by all C. perfringens strains, is essential for necro-haemorrhagic enteritis. In addition to alpha toxin, other C. perfringens toxins and/or enzymes might contribute to the pathogenesis of necro-haemorrhagic enteritis. These additional virulence factors might contribute to breakdown of the protective mucus layer during initial stage of pathogenesis, after which alpha toxin, either or not in synergy with other toxins such as perfringolysin O, can act on the mucosal tissue. Furthermore, alpha toxin alone does not cause intestinal necrosis, indicating that other virulence factors might be needed to cause the extensive tissue necrosis observed in necro-haemorrhagic enteritis. This review summarizes recent research that has increased our understanding of the pathogenesis of bovine necro-haemorrhagic enteritis and provides information that is indispensable for the development of novel control strategies, including vaccines

Thermic dehorning and ear tagging as atypical portals of entry of Clostridium tetani in ruminants

This paper describes two infections with Clostridium tetani (C. tetani). One outbreak occurred after dehorning of calves, the second infection happened after ear tagging of a goat. In the first case 3 young Holstein Friesian calves showed generalized stiffness, severe lock-jaw and bloat two weeks after dehorning. The thermal dehorning wounds were identified as the infection sites of C. tetani by bacterial culture and PCR. The second case was a three-year old male castrated goat, with generalized stiffness. The animal had been ear tagged one week prior to the onset of the symptoms. C. tetani could be cultured from pus on the ear tag. Treatment was attempted in two calves and the goat. Wounds were debrided and disinfected, penicillin and anti-tetanus serum were administered and polyionic perfusions provided. In addition, the goat was vaccinated against tetanus. The goat and one calf fully recovered after 36 and 8 days respectively. To the authors' knowledge a tetanus outbreak in association with thermal dehorning has not been described previously. Also ear tagging as a possible cause for C. tetani infection has not been described in goats

Intestinal obstruction by Toxocara vitulorum in a calf

A one-month-old Belgian blue bull calf was referred to the animal hospital of the Faculty of Veterinary Medicine (UGhent) because of the sudden onset of severe colic. The animal showed intermittent recumbency, kicking to the abdomen, abdominal distension of the right quadrants, absence of feces and fluid-splashing and the presence of ping sounds on auscultation of the right side. Abdominal ultrasound showed distended, but still contractile small intestines with thickened walls. On exploratory laparotomy, a complete obstruction with adult Toxocara vitulorum extending from duodenum to mid-jejunum was diagnosed. On the punctum maximum of the obstruction, the ascarides were partially removed through an enterotomy. After vermifugation with doramectin, ascarides were found in the animal's feces in the next days. In contrast to ascaride infections in puppies, piglets and foals, to the author's knowledge, intestinal obstruction caused by T. vitulorum has not been described previously in calves

Surgical correction of pyelonephritis caused by multidrug-resistant Escherichia coli in a dairy cow

A four-year-old red Holstein Friesian cow was admitted to the clinic with fever and milk drop. Blood analysis revealed the presence of a chronic infection, and the diagnosis of pyelonephritis of the right kidney was made after repeated ultrasound examinations. The animal was treated with procaine benzylpenicillin, sulfadoxine trimethoprim, oxytetracycline and enrofloxacine but this therapy was not successful. Nephrectomy was performed after the left kidney proved to have a normal function. The removed right kidney was greatly enlarged and filled with pus. Escherichia coli was isolated from the kidney. The strain was multidrug-resistant, including resistance to aminopenicillins, streptomycin, sulfonamides and trimethoprim. The cow was treated with amoxicillin and clavulanic acid after the operation. Postoperatively, an abscess developed and a tube drain was placed during a second surgery to enable daily rinsing with a chlorhexidine solution. After a postoperative care period of two months, the animal was sent back to the farm, where it returned to an acceptable level of milk production. This case demonstrates that with basic surgical skills, a good preparation and knowledge of anatomy, nephrectomy is attainable for a first-opinion veterinarian, with an acceptable economic prognosis for the farmer

The C-terminal domain of Clostridium perfringens alpha toxin as a vaccine candidate against bovine necrohemorrhagic enteritis

Bovine necrohemorrhagic enteritis is caused by Clostridium perfringens and leads to sudden death. Alpha toxin, together with perfringolysin O, has been identified as the principal toxin involved in the pathogenesis. We assessed the potential of alpha toxin as a vaccine antigen. Using an intestinal loop model in calves, we investigated the protection afforded by antisera raised against native alpha toxin or its non-toxic C-terminal fragment against C. perfringens-induced intestinal necrosis. Immunization of calves with either of the vaccine preparations induced a strong antibody response. The resulting antisera were able to neutralize the alpha toxin activity and the C. perfringens-induced endothelial cytotoxicity in vitro. The antisera raised against the native toxin had a stronger neutralizing activity than those against the C-terminal fragment. However, antibodies against alpha toxin alone were not sufficient to completely neutralize the C. perfringens-induced necrosis in the intestinal loop model. The development of a multivalent vaccine combining the C-terminal fragment of alpha toxin with other C. perfringens virulence factors might be necessary for complete protection against bovine necrohemorrhagic enteritis