Labile neurotoxin in serum of calves with "nervous" coccidiosis

Mouse inoculation was used to test for the presence of a toxin in the serum, cerebrospinal fluid, and intestinal contents collected from cases of bovine enteric coccidiosis, with and without neurological signs, and from control calves. Intravenous inoculation of mice with 10 mL/kg of serum from calves showing nervous signs caused effects significantly different from those caused by the inoculation of serum from calves not showing nervous signs and from control calves. The effect was particularly evident in female mice. At this dosage severe neurological signs such as loss of righting reflex, seizures and death occurred only with serum from calves with "nervous coccidiosis". The results suggest that serum from the calves with neurological signs contains a neurotoxin. This toxin appears to be highly labile. It was not present in the cerebrospinal fluid at levels comparable to those in the serum. The significance of this labile neurotoxin with respect to the pathogenesis of the neurological signs associated with bovine enteric coccidiosis is unknown.     

A Brief Review of Bovine Coccidiosis in Western Canada

Coccidiosis of beef cattle, in both its enteric and nervous forms, seen in feedlots in Western Canada is discussed. Cases of coccidiosis accompanied by nervous signs, occasionally up to 30% of those affected enterically, are most common during the coldest winter months. The pathogenesis of the nervous form of the disease is unknown. Clinical management of disease outbreaks using various chemotherapeutics is described. The importance of using anticoccidial drugs before the onset of clinical signs in cattle in contact with sick animals is discussed.     

Role of IgE in the pathogenesis of bovine respiratory syncytial virus in sequential infections in vaccinated and nonvaccinated calves

A study was undertaken to evaluate the possible role of IgE in the pathogenesis of bovine respiratory syncytial virus (BRSV) infection. Fifteen calves were allotted at random to 3 treatment groups. One group of 6 calves was vaccinated with attenuated BRSV vaccine before live-virus challenge exposure, another group of 6 was not vaccinated before challenge exposure, and the remaining 3 calves served as controls (nonvaccinated, nonchallenge exposed). Calves of the 2 experimental groups were exposed to 2 live-virus aerosolizations (challenge exposure) 35 days apart. Histamine and BRSV-specific IgE (BRSV-IgE) concentrations in serum, lung lavage fluid, and nasopharyngeal exudate, as well as clinical signs of disease, were evaluated for 14 days after each challenge exposure. Vaccination before challenge exposure with live BRSV appeared to have little or no effect on the severity of the disease, but did appear to affect disease persistence. A correlation (P less than 0.02) existed between signs of disease and BRSV-IgE concentration measured in lung lavage fluid, but this was only true for vaccinated calves. Although no other correlations were found between clinical signs of disease and IgE concentration, analysis of the results additionally revealed a strong correlation (P less than 0.002) between disease signs and histamine concentration in nasopharyngeal exudate from calves of both experimental groups. Thus, indirect evidence implicated IgE in BRSV infection pathogenesis.     

Evaluation of lasalocid as a coccidiostat in calves: titration, efficacy, and comparison with monensin and decoquinate

Two experiments were conducted to evaluate lasalocid as a coccidiostat in Holstein calves and to compare lasalocid with monensin and decoquinate. In experiment 1, calves in 3 groups (6 calves/group) were each inoculated with 500,000 sporulated oocysts, 88% of which were Eimeria bovis and 12% were E zuernii. Calves in each group were given lasalocid-medicated feed at 0.50 (group 3), 0.75 (group 4), or 1 mg/kg (group 5) of body weight/day for 45 days. Two control groups (6 calves/group) were also evaluated; calves in control group 2 were inoculated and nontreated, and calves in control group 1 were noninoculated and nontreated. At 0.50, 0.75, or 1 mg/kg/day, lasalocid was equally effective in preventing induced coccidiosis (E bovis and E zuernii) in calves. Compared with inoculated nontreated controls, treated calves had significantly (P less than 0.05) fewer oocysts in feces and had fewer clinical signs of coccidiosis from days 16 to 30 after inoculation. Experiment 2 was conducted to compare the effectiveness of monensin, lasalocid, and decoquinate for the prevention of experimentally induced coccidiosis. Calves (n = 48) were allotted into 4 groups (12 calves/group); each was inoculated orally with 275,000 sporulated oocysts, predominantly E bovis and E zuernii, and each was given nonmedicated feed (group 6) or feed medicated with 33 mg of lasalocid (group 7), decoquinate (group 8), or monensin (group 9)/kg of feed for 46 days. Calves given medicated rations had significantly (P less than 0.05) fewer oocysts in their feces and fewer clinical signs of coccidiosis than did calves given nonmedicated rations.(ABSTRACT TRUNCATED AT 250 WORDS)     

Nervous disease associated with coccidiosis in young cattle

Four cases are described of nervous disease associated with coccidiosis in young cattle. Prodromal nystagmus, ventromedial strabismus, sternal or lateral recumbency with contortions of the head and neck, near normal interictal periods and palpable proctitis were common findings. Differentiation from other nervous disorders in young cattle and the pathogenesis of the nervous signs associated with coccidiosis are discussed. It is suggested that the clinical picture is sufficiently distinctive to allow a diagnosis to be made on clinical grounds alone.     

Copper deficiency in the young bovine results in dramatic decreases in brain copper concentration but does not alter brain prion protein biology

An Mn for Cu substitution on cellular prion proteins (PrP(c)) in the brain that results in biochemical changes to PrP(c) has been implicated in the pathogenesis of transmissible spongiform encephalopathies. Recent research in the mature bovine does not support this theory. The present study tested this hypothesis by using progeny from gestating cows receiving Cu-deficient diets or Cu-deficient diets coupled with high dietary Mn. Copper-adequate cows (n = 39) were assigned randomly to 1 of 3 treatments: 1) control (adequate in Cu and Mn), 2) Cu deficient (-Cu), or 3) Cu deficient plus high dietary Mn (-Cu+Mn). Cows assigned to treatments -Cu and -Cu+Mn received no supplemental Cu and were supplemented with Mo to further induce Cu deficiency. The -Cu+Mn treatment also received 500 mg of supplemental Mn/kg of dietary DM. Calves were weaned at 180 d and maintained on the same treatments as their respective dams for 260 d. Copper-deficient calves (-Cu and -Cu+Mn) had decreased (P = 0.001) brain (obex) Cu and tended to have increased (P = 0.09) obex Mn relative to control calves. Obex Mn:Cu ratios were substantially increased (P < 0.001) in calves receiving -Cu and -Cu+Mn treatments compared with control calves and were greater (P < 0.001) in -Cu+Mn calves than in -Cu calves. Obex prion protein characteristics, including proteinase K degradability, superoxide dismutase (SOD)-like activity, and glycoform distributions, were largely unaffected. Obex tissue antioxidant capacity was not compromised by perturbations in brain metals, but Cu-deficient calves tended to have decreased (P = 0.06) Cu:Zn SOD activity and increased (P = 0.06) Mn SOD activity. Although obex Cu was decreased because of Cu deficiency and Mn increased because of exposure to high dietary Mn, the obex metal imbalance had minimal effects on PrP(c) functional characteristics in the calves.     

A bovine virus diarrhea calfhood vaccination trial in a persistently infected herd: effects on titres, health and growth.

A controlled calfhood vaccination trial to prevent bovine virus diarrhea was conducted in a 100 head cow-calf operation with a three year history of annual calf losses due to enteric bovine virus diarrhea (persistently infected herd). Approximately 50% of the calves were vaccinated at six, 12 and 24 weeks of age. Paired serum samples and growth data were collected on three occasions for comparison between vaccinates and controls. Three vaccinated calves died of enteric bovine virus diarrhea in the first year of the trial and one nonvaccinated calf died in the second year. Two of the three vaccinated calves had developed bovine virus diarrhea virus neutralization antibody titres of 2048 or greater before developing clinical signs. The control and third vaccinated calf failed to seroconvert before dying of enteric bovine virus diarrhea. Approximately 90% of the vaccinated calves seroconverted compared to approximately 40% of the controls. Paired serum samples collected from 75% of the cows in the spring, summer and fall of each year of the trial, showed persistent high bovine virus diarrhea virus neutralization titres in all samples. Calf vaccination before 12 weeks of age had little effect on seroconversion due to high levels of passive antibody to bovine virus diarrhea. Growth data showed that there was no improvement in weight gain or rate of growth in the vaccinated calves.     

Asymptomatic encephalitis in calves experimentally infected with bovine herpesvirus-5

This study demonstrated that bovine herpesvirus 5 (BoHV)-5 infected calves can develop encephalitis and remain asymptomatic. Seven calves were infected intranasally and monitored for 30 days. Cerebrospinal fluid (CSF) analysis was performed from the onset of neurological signs. Multiple sections of brain and the trigeminal ganglion were submitted to histopathology. Virus detection (PCR and isolation) was performed on CSF and tissues. Four calves developed signs of neurologic disease and died. Three calves remained asymptomatic and were euthanized 30 days post-infection. Cerebrospinal fluid mononuclear pleocytosis occurred in symptomatic and asymptomatic calves. BoHV-5 was isolated and viral DNA was detected in multiple areas of the encephalon of all calves. The viral DNA was detected in the CSF of 2 calves showing neurological signs. Histologically, inflammation was noted in the brain of all calves and confirmed that the encephalitis caused by BoHV-5 may be mild and asymptomatic.     

武威某奶牛场犊牛及职工球虫病感染情况调查

为摸清该奶牛场的球虫感染情况,在甘肃省武威市某集约化牛场随机抽10头犊牛粪便及与犊牛直接接触的一线职工10人的粪便为样本,采用麦克马斯特计数方法,检测球虫病的感染情况。结果显示：该牛场球虫总感染率为80%,但OPG均小于5000,属于亚临床型球虫感染,该奶牛场职工没有球虫病感染情况。通过对球虫病感染的检查,诣在为该场犊牛球虫病的防控治疗提供依据。     

Effect of bovine fibroblast interferon on rhinovirus infection in calves.

The prophylactic/therapeutic activity of natural bovine fibroblast interferon (BoF-IFN) against bovine rhinovirus infection in calves was assessed. Six calves were each given 8 intranasal inoculations of partially purified BoF-IFN (3.25 x 10(5) U at 8 AM, 11 AM, 5 PM, and 8PM on day 1 and 8 AM, 11 AM, 2 PM, and 5PM on day 2), and 6 calves were given placebo. All calves were challenge exposed with 10(5.1) TCID50 of bovine rhinovirus after the first 2 treatments (6 hours after the first IFN or placebo treatment). Nasal excretion of rhinovirus, IFN concentration in the nasal secretions, and nasal secretion and serum rhinovirus antibodies were measured before and at selected times after calves were inoculated. Interferon-treated calves excreted rhinovirus in their nasal secretions in lesser amounts (mean value, 0.84 log10 TCID50/ml vs 1.58 log10 TCID50/ml on postchallenge exposure days 1 and 2; (P less than 0.05) and for a shorter duration (P less than 0.05) than did placebo-treated calves. No calves developed clinical signs of respiratory tract illness. Rhinovirus antibody titer was not significantly different between IFN- and placebo-treated calves.     

Neurological signs associated with coccidiosis in a beef steer

Abstract

Extract

Although neurological signs have been associated with enteric coccidiosis in calves in North America and Australia (Jubb, 1988 Jubb, TF. 1988. Nervous disease associated with coccidiosis in young cattle. Australian Veterinary Journal, 65: 353–354.  [Google Scholar]; Radostits and Stockdale, 1980 Radostits, OM and Stockdale, PHG. 1980. A brief review of bovine coccidiosis in Western Canada. Canadian Veterinary Journal, 21: 227–230.  [Google Scholar]), they have not been described in cattle in New Zealand.     

First report and histological features of Chlamydia pecorum encephalitis in calves in New Zealand

CASE HISTORY: Between September and October 2013, 40 of 150 crossbred Friesian dairy calves on a farm in the Manawatu region of New Zealand developed neurological signs when between 1 and 3 months of age. Calves were grazed in multiple mobs and calves from each mob were affected. A variable response was observed to initial treatment with thiamine, fluoroquinolone antibiotics and non-steroidal anti-inflammatory drugs.

CLINICAL AND PATHOLOGICAL FINDINGS: Affected calves exhibited a range of neurological signs that included generalised depression, hind limb ataxia with a stiff gait, and knuckling of the fetlocks. In advanced cases, calves became recumbent with opisthotonous. Over a 4-week period, 13 calves died or were subject to euthanasia and a thorough necropsy was performed on three of these calves. Necropsy findings included fibrinous peritonitis, pleuritis and pericarditis, with no gross abnormalities visible in the brain or joints. Histology of the brain was possible in seven of the affected calves, with lesions ranging from lymphocytic and histiocytic vasculitis and meningoencephalitis, to extensive thrombosis and neutrophilic inflammation. Immunohistochemistry using an anti-chlamydial lipopolysaccharide antibody revealed positive immuno-staining in all seven cases, with no brain samples exhibiting immunostaining for Histophilus somni. DNA was extracted from a sample of fresh brain from one case and chlamydial DNA sequences were amplified by PCR and found to be identical to Chlamydia pecorum. PCR was also performed on formalin-fixed brain tissue from three of the other cases, but no chlamydial DNA was amplified.

DIAGNOSIS: Chlamydia pecorum meningoencephalomyelitis (sporadic bovine encephalomyelitis).

CLINICAL RELEVANCE: This is the first time that C. pecorum has been confirmed as a cause of clinical disease in New Zealand. Practitioners should be aware of this disease as a differential in calves with neurological signs, and submit samples of formalin-fixed brain as well as fresh brain to enable confirmation of suspected cases using PCR analysis. Furthermore, these cases illustrate that the histological lesions in the brains of calves with C. pecorum are more variable than previously reported, and pathologists should be aware that histological features may overlap with those traditionally ascribed to other organisms, such as H. somni.     

Hematology of the neonatal calf. III. Frequency of congenital iron deficiency anemia.

The hematocrits of 258 Holstein-Friesian and Jersey calves were determined during the first 3 days following birth. Hematocrit values of 25% or less were observed in 15.8% of the calves and hematocrits of 20% or less were observed in 6.9% of calves from apparently normal dams. The serum iron concentration of neonatal calves with hematocrits of 25% or less was significantly lower than the value recorded in calves with hematocrits above 25% and there was a direct correlation between PCV and serum iron concentration. The data presented suggested that prenatal development of iron deficiency is an important cause of anemia in neonatal dairy calves. Factors which may be important in pathogenesis are discussed.     

Clinical efficacy of chlortetracycline hydrochloride administered in milk replacer to calves

Two similar groups of 14 calves were housed and fed identically in individual pens on a calf-rearing farm. The groups were balanced for weight and immunological status as determined by zinc sulphate turbidity values. When an outbreak of enteric and respiratory disease occurred one group was treated with 20 mg chlortetracycline hydrochloride/kg bodyweight daily for seven consecutive days, by adding the active ingredient to the milk replacer, while the other group was left untreated. Both groups received additional therapy as required. The calves were examined daily during the period of treatment and the clinical observations were assessed and analysed statistically. There was a significant difference between the clinical scores of the two groups on the second day of treatment (P less than 0.05) and on all subsequent days (P less than 0.01) indicating that the calves receiving chlortetracycline hydrochloride were less affected by the disease outbreak. The abnormal enteric and respiratory signs were associated with several potential pathogens including bacteria, viruses and protozoa. The treatment was therefore effective against enteric and respiratory disease involving several organisms.     

Clinical signs following experimental lungworm infection and natural bovine respiratory syncytial virus infection in calves

Similar clinical signs have been reported in calves infected either by Dictyocaulus viviparus or bovine respiratory syncytial virus. Three experiments were carried out to establish the clinical picture and the course of the disease in animals with these infections. The clinical signs of calves infected with lungworm included coughing, nasal discharge, tachypnoea, abdominal breathing and pyrexia, and auscultation of their lungs revealed increased bronchial sounds. Similar signs were also observed after infection with bovine respiratory syncytial virus, but the signs were more acute and resolved more rapidly than in animals infected with lungworm larvae. Calves infected with lungworm had more serious clinical signs after infection with bovine respiratory syncytial virus than calves, which were not infected with lungworm.     

Toll-like receptor expression in the nervous system of bovine alpha-herpesvirus-infected calves

In this study, the expression levels of viral Toll-like receptors (TLRs) in the nervous system of bovine herpesvirus type 5 (BoHV-5)-infected calves were investigated. A significant increase in the expression of TLRs 3 and 7–9 was found in the anterior cerebral cortex during acute infection and viral reactivation. In the trigeminal ganglia, only TLR9 expression was significantly affected. The magnitude of the increase was lower in BoHV-1-infected calves, suggesting that a restricted immune response might protect against exacerbated inflammatory responses in the brain. This work describes, for the first time, the involvement of TLRs 3 and 7–9 in the recognition of BoHV in the bovine nervous system, indicating that the expression of these receptors might be associated with the development of neurological disease. Modulation of the signalling pathways mediated by TLRs might provide an effective approach to control the neuro-immune response to BoHV-5, which may be responsible for neurological lesions.     

Effects in calves of mixed infections with bovine viral diarrhea virus and several other bovine viruses

The objective of this study was to verify whether a mixed infection in calves with bovine viral diarrhea virus (BVDV) and other bovine viruses, such as bovid herpesvirus-4 (BHV-4), parainfluenza-3 (PI-3) and infectious bovine rhinotracheitis (IBR) virus, would influence the pathogenesis of the BVDV infection sufficiently to result in the typical form of mucosal disease being produced.

Accordingly, two experiments were undertaken. In one experiment calves were first infected with BVDV and subsequently with BHV-4 and IBR virus, respectively. The second experiment consisted in a simultaneous infection of calves with BVDV and PI-3 virus or BVDV and IBR virus.

From the first experiment it seems that BVDV infection can be reactivated in calves by BHV-4 and IBR virus. Evidence of this is that BVDV, at least the cytopathic (CP) strain, was recovered from calves following superinfection. Moreover, following such superinfection the calves showed signs which could most likely be ascribed to the pathogenetic activity of BVDV. Superinfection, especially by IBR virus, created a more severe clinical response in calves that were initially infected with CP BVDV, than in those previously given the non-cytopathic (NCP) biotype of the virus. Simultaneous infection with PI-3 virus did not seem to modify to any significant extent the pathogenesis of the experimentally induced BVDV infection whereas a severe clinical response was observed in calves when simultaneous infection was made with BVDV and IBR virus.