Intestinal cryptosporidiosis in calves on a dairy farm

Oocysts of Cryptosporidium species were identified in the faeces of scouring calves from a dairy farm. The faeces were watery and greenish yellow but the calves were usually alert and not desiccated when they were admitted to the clinic. Without treatment they became severely desiccated and recumbent within a few hours, but after symptomatic treatment they improved rapidly. The importance of cryptosporidiosis as a herd health problem is discussed.     

Enterocolitis in spontaneous cryptosporidiosis infections in calves

The pathology of lesions in the intestines of 48 calves with spontaneous cryptosporidiosis was studied by histological examination and by scanning electron-microscopy (SEM). The animals were 7 to 21 days old, emergency-slaughtered mostly for dehydration and diarrhoea. Identical lesions were observed in the jejunum and ileum. The villi, often infected by cryptosporidia on a mass scale, were shortened, atrophic, markedly curved and shrunk in their ultrastructure, often as a result of the regression of groups of enterocytes with cryptosporidia, the adjacent tissue being affected, at the same time, by nodular hyperplasia. The enterocytes harbouring the protozoans exhibited cuboidal up to squamous metaplasia; in ultrastructure they had not hexagonal shape and showed signs of microvillus regression. The cryptosporidiosis of the small intestine was always accompanied by hyperaemia and inflammatory reactions in lamina propria, mostly non-purulent, with numerous eosinophils. Signs of typhlitis in the caecum--more frequent and intensive than in other parts of the large intestine infected by cryptosporidia--were characterized, in most cases, by lesions in the covering epithelium and by mostly non-purulent inflammatory infiltration with a large admixture of eosinophils in lamina propria. No inflammatory lesions were found in the colon and rectum. Severe cryptosporidial infections of large parts of intestine and the nature of pathological lesions lead to a considerable reduction in the total absorption surface of the intestine and are potential causes of diarrhoea from malabsorption.     

A retrospective study of dystocia-related vertebral fractures in neonatal calves

Forty-seven cases of neonatal vertebral fractures/luxations occurred in a 21 year period (1967-1987). All of the fractures were located between the 11th thoracic vertebra and the fourth lumbar vertebra; 77% occurred at the thoracolumbar junction. All but one case was associated with a forced extraction, either unspecified (53%), mechanical (28%), or manual (17%).

A weak calf or continuous recumbency since birth was the major clinical sign. Hemorrhage around the kidneys, adrenal glands, and in perivertebral muscles was a consistent necropsy finding and a useful indicator that a thoracolumbar fracture was present. In addition to the vertebral fracture, the prominent necropsy findings were subdural and epidural hemorrhage, myelomalacia, spinal cord compression or severed spinal cord, and fractured ribs. All of the calves died or were euthanized without regaining locomotory function.

     

Evaluation of colostrum and whey-derived gamma globulins for prevention of cryptosporidiosis in artificially infected neonatal calves

Thirty colostrum-deprived Friesian male calves were used to study the effect of colostrum and whey-derived gammaglobulins on the clinical events and oocyst-excretion pattern following artificial infection with a fresh, field-sourced strain of Cryptosporidium parvum. The calves were raised naive and free from contact with C. parvum from birth until infection at either 10 or 17 days of age. The two age groups comprised three sub-groups that were each given a single treatment of colostrum, whey-derived gammaglobulins or whole milk (controls) at 5 hours after birth. Blood samples taken both before and 48 hours after this dosing showed the mean serum gamma globulin concentrations changed from almost zero in all calves to 462,279 and 29 mg/dl for the colostrum, whey-derived gammaglobulin and whole milk sub-groups respectively. The results showed that a majority of calves shed Cryptosporidium oocysts within 7 days of oral infection but that no diarrhoea or other clinical signs were associated with this. However, when the level of C. parvum faecal shedding was graded, the results showed a trend towards a higher level of oocyst shedding and over a longer period of time in the control calves deprived of any passive immunity than in the two groups given either colostrum or whey-derived gammaglobulins.     

Scanning and transmission electron microscopic observations on the host-parasite relationship in intestinal cryptosporidiosis of neonatal calves

The association of cryptosporidia with the intestinal epithelium of three neonatal calves was studied by scanning (SEM) and transmission (TEM) electron microscopy. Trophozoites and schizonts were observed embedded in the microvillous brush border of epithelial cells. Merozoites, released from schizonts, were seen free in the lumen and penetrating epithelial cells by SEM and TEM. Incorporation of microvilli into the parasitophorous envelope of trophozoites was seen by TEM. These findings indicate that cryptosporidia develop at an intracellular position in the apex of the epithelial cells following merozoite penetration.     

Experimental cryptosporidiosis in mice, calves and chicken

Experimental infections attributed solely to Cryptosporidium were carried out in newborn SPF mice, calves and chicken in order to study the prepatency, patency and incubation periods, describe the clinical symptoms and find and describe any correlations between the association of Cryptosporidium with the intestinal mucosa and presence of pathological lesions. The paper also gives the clinical and paarsitological parameters of Cryptosporidium infection of calves from a field survey and compares them to the results of experimental study.     

The effect of a single disinfection of a farm on cryptosporidiosis infection in calves

The disinfection of a farm with Dikonit (active substance: sodium dichlorocyanuran) exerted no significant influence on the course of the spreading of cryptosporidiosis infections in newborn calves. The oocysts of Cryptosporidium sp., isolated from the faeces of a spontaneously infected calf and left in a 2.5% disinfecting solution of Dikonit under laboratory conditions for four hours, did not lose their viability. Laboratory mice experimentally infected with these "disinfected" oocysts, began to produce oocysts of Cryptosporidium sp. the sixth day from infection. The findings of different developmental stages of this protozoan obtained during the histological examination of the intestinal tissue of test mice are also considered as evidence of successful experimental infection. The cryptosporidium-free period which lasted only 14 days from disinfection was mainly due to thorough mechanical cleaning of the area where the calves were kept after birth. This is also proved by the results of the examination of old residues of calf faeces scraped from the floors: only individual individual oocysts of Cryptosporidium sp. were found in these samples.     

Evaluation of beta-cyclodextrin against natural infections of cryptosporidiosis in calves

The effectiveness of beta-cyclodextrin, excipient used in pharmaceutical industry, in the treatment of natural infection by Cryptosporidium parvum in suckling calves, was evaluated. Administration of the drug at a dose of 500 mg/kg body weight for 3 consecutive days from birth (prophylactically) or following confirmation of the infection (therapeutically) decreased the severity of diarrhoea and shortened the duration of oocyst shedding.     

Enterotoxemia in neonatal calves

The incidence, bacterial characteristics, disease syndromes, diagnosis, treatment, and prevention of enterotoxemia of neonatal calves caused by Clostridium perfringens (Types A, B, C, D, and E) are reviewed.     

Field study of the efficacy of halofuginone and decoquinate in the treatment of cryptosporidiosis in veal calves

Ninety, seven- to 10-day-old calves were allocated to three groups of 30 and treated daily for seven days with either 100 microg/kg halofuginone hydrobromide or 2.5 mg/kg decoquinate orally or left untreated as controls. The levels of diarrhoea and dehydration were monitored daily for 28 days from the first day of treatment (day 0) and samples of faeces were collected on days 0, 7, 14, 21 and 28, to quantify the excretion of Cryptosporidium parvum oocysts. The calves were weighed on days 3 and 28. The treatments had no effect on the levels of diarrhoea or dehydration, the proportions of diarrhoeic calves or the proportions of calves shedding oocysts. However, unlike decoquinate, halofuginone significantly reduced the excretion of oocysts on day 7 (P<0.0001), and decoquinate increased the average daily weight gain of the calves (P=0.049).     

Controlling the onset of natural cryptosporidiosis in calves with paromomycin sulphate

A prospective, controlled-blind field trial was conducted to evaluate the efficacy and safety of paromomycin sulphate, given for 10 days from birth, in preventing natural cryptosporidiosis in calves. In the untreated control group, oocyst shedding and diarrhoea followed the pattern that had occurred on the farm before the trial, consistent with a perinatal infection, whereas in the treated group, the prepatent period was significantly longer than in the control group (P < 0.01) and oocyst shedding and diarrhoea started only after the drug was withdrawn. However, the regimen did not reduce the incidence of disease in the treated group.     

A Bayesian evaluation of four immunological assays for the diagnosis of clinical cryptosporidiosis in calves

A Bayesian approach was used to evaluate four immunological assays for the clinical diagnosis of cryptosporidiosis in calves: an immunofluorescence assay (IFA), two ELISA tests and an immunochromatographic (dipstick) assay. Faecal samples from 287 calves aged less than 6 weeks with clinical signs of gastrointestinal disease were examined for the presence of Cryptosporidium spp. The high prevalence (63%) of Cryptosporidium spp. indicated the relevance of this agent in the aetiology of diarrhoea in calves. All diagnostic assays were found to be relatively specific (IFA: 94.8%; Tetra ELISA: 95.9%; Techlab ELISA: 92.7%; dipstick assay: 91.5%) and sensitive (IFA: 97.4%; Tetra ELISA: 93.6%; Techlab ELISA: 95.4%; dipstick: 87.8%). Despite a lower sensitivity, the dipstick assay provided a practical alternative to laboratory diagnosis of clinical cryptosporidiosis in calves.     

A comparison of dichromate solution floatation and fecal smears for diagnosis of cryptosporidiosis in calves

Fecal samples from eleven calves experimentally infected with cryptosporidia were examined by two methods to evaluate their sensitivity and ease of use as diagnostic techniques. Comparison of a dichromate solution floatation and fecal smear techniques indicated that the former method was more sensitive. Oocysts were detected in feces earlier and for a longer period following exposure, and were easier to visualize using the dichromate solution floatation procedure. In addition, the dichromate solution floatation technique eliminated Candida albicans which can sometimes be confused with cryptosporidial oocysts in fecal smears. Another advantage was that oocysts could readily be detected in fecal samples stored as long as 120 days in dichromate solution. Using the dichromate solution floatation technique, it was shown that shedding of cryptosporidial oocysts in feces occurred from two to 20 days after oral challenge but was not always accompanied by diarrhea. Infection with cryptosporidia was confirmed in two calves at necropsy. Calves which were not sacrificed for portmortem examination recovered without treatment. The dichromate solution floatation technique is simple, rapid, inexpensive and should facilitate detection of cryptosporidia by diagnostic laboratories and some veterinary practitioners.     

Efficacy of halofuginone lactate in the prevention of cryptosporidiosis in dairy calves

To evaluate the efficacy of halofuginone lactate (Halocur; Intervet) when used prophylactically against cryptosporidiosis in dairy calves, 513 Holstein heifer calves were randomly distributed between two experimental groups. Those in the treatment group (n=259) received 0.1 mg halofuginone base per kg bodyweight daily in a 10 ml solution, for the first seven days following birth, while those in the control group (n=254) received an equal volume of a placebo solution. Faecal samples were collected weekly from all calves until three weeks of age to test for Cryptosporidium oocysts and to assess the diarrhoeal status. Growth parameters of the calves were also recorded at approximately four months of age. Calves that received halofuginone were significantly less likely to shed Cryptosporidium oocysts during the course of the study than placebo-treated calves (odds ratio 0.6, 95 per cent confidence interval 0.4 to 0.9, P=0.009). Mean growth measurements of calves in the treated group were consistently higher than those of the control calves (hipometer-derived P=0.052, wither height P=0.097) and mortality was lower in the treated group (P=0.07). However, these differences were not statistically significant (P>0.05). No association was found between the prophylactic use of halofuginone and the incidence of calf diarrhoea.     

Efficacy of halofuginone lactate in the prevention of cryptosporidiosis in suckling calves

The efficacy of halofuginone lactate in the prevention of cryptosporidiosis in suckling calves was evaluated in a multicentre, control versus placebo, randomised, double-blind clinical trial. Seventy-eight six- to 48-hour-old calves were treated daily with 120 microg/kg bodyweight of halofuginone lactate administered orally for seven consecutive days, while 80 calves received a placebo. Faecal samples were collected on the first day of dosing and four, seven, 14 and 21 days later, and Cryptosporidium parvum oocysts were counted and faecal indices for diarrhoea were determined after a clinical examination. An analysis of variance for repeated measurements showed a highly significant difference in favour of halofuginone lactate for both the oocyst counts (P=0.0002) and the faecal diarrhoea indices (P=0.0001) throughout the trial. The difference was greatest after seven days, when the mean oocyst count of the placebo group was 2.5 times and its mean faecal index was twice the mean of the halofuginone lactate group. One day after the end of the treatment the calves which received halofuginone lactate excreted 44 per cent fewer C parvum oocysts and 44 per cent fewer of them had diarrhoea. The reduction was even greater (65 per cent) when liquid diarrhoea was assessed, with 32.5 per cent of the calves in the placebo group having liquid diarrhoea compared with 11.5 per cent in the halofuginone lactate group. The treatment was well tolerated and easily administered.     

Efficacy of alpha-cyclodextrin against experimental cryptosporidiosis in neonatal goats

The efficacy of orally administered tablets containing alpha-cyclodextrin, an excipient used in the pharmaceutical industry with demonstrated anticryptosporidial activity in vitro and in neonatal mice, was evaluated in neonatal goat kids. The formulation was evaluated for hardness and was subjected to in vitro drug release studies. Twenty goat kids were orally inoculated with 10(6) oocysts of C. parvum within the first 6 days of age. Half of the animals were treated by oral administration of four tablets of alpha-cyclodextrin/day (500 mg/kg of body weight) for six consecutive days, the treatment beginning on the day of inoculation. Infection was monitored by daily examination of faecal samples from the first day to 25 days post-inoculation. The criteria studied in evaluating efficacy were: oocyst shedding, presence of diarrhoea and weight gain at 15 and 25 days post-inoculation. alpha-cyclodextrin was effective when given at the beginning of infection: there was a longer pre-patent period, a reduction in the patent period and a decrease in the intensity of infection, these differences being statistically significant (P < 0.05) compared with untreated neonatal kids. Moreover, except in one animal, the diarrhoea was prevented in infected neonatal kids. Animals from both groups increased the body weight and no significant differences were seen between the two groups.     

Systemic mycosis in neonatal calves

Extract

It is perhaps surprising that, although the freezing industry has been in existence in New Zealand for as long as export of perishable primary products has been practised, it is only within the last few years that veterinary interest in this aspect has quickened. As far as meat products are concerned, this has come about by pressure from overseas customers for increased direct supervision by professional staff rather than from the inclination of industry or government in this country. None the less, one result has been, and will be in increasing measure, to bring into sharper focus the usefulness of works to agriculturalists in a sense beyond the conversion to cash of one of the major end-products of farming operations.     

Efficacy of azithromycin dihydrate in treatment of cryptosporidiosis in naturally infected dairy calves

The objective of this study was to evaluate the therapeutic efficacy of azithromycin treatment of cryptosporidiosis in naturally infected calves under field conditions. Fifty Holstein calves with cryptosporidiosis infection were divided into 5 groups: 1 group (10 calves) was unmedicated and served as the control group and was given distilled water only, whereas the other groups (10 animals per group) were medicated orally with azithromycin at the doses of 500 (group 1), 1,000 (group 2), 1,500 (group 3), and 2,000 mg (group 4) PO once daily for 7 days. The animals were examined clinically and fecal samples were collected on the 1st (inclusion day), 7th, 14th, and 21st days of the study. Drug efficacy was assessed by evaluating diarrhea, oocyst shedding, and weight gains from days 1 to 21 (4 assessments). Significant differences were observed in reductions of oocyst shedding (P < .05) and the fecal diarrhea incidence (P < .05) in groups 3 and 4 when compared with groups 1 and 2 and the control group. Weight gain of medicated calves was significantly higher than that of the unmedicated calves throughout the study (P < .05). The drug significantly suppressed oocyst shedding and resulted in significant improvements in clinical signs. Therefore, this suppression may have significant effect on the reduction of environmental contamination by cryptosporidial oocysts. From the economic point view, authors suggest that the most effective dose of azithromycin for the treatment of cryptosporidiosis in calves should be at 1,500 mg/d for 7 days.