Duration of naturally acquired giardiosis and cryptosporidiosis in dairy calves and their association with diarrhea

OBJECTIVE: To determine duration of infection and association of infection with diarrhea for dairy calves with naturally acquired cryptosporidiosis and giardiosis. DESIGN: Cohort study. ANIMALS: 20 Holstein calves on a single dairy farm. PROCEDURE: Fecal samples were collected 3 times/wk for the first 45 days after birth, then weekly until calves were 120 days old and examined for Giardia duodenalis cysts and Cryptosporidium parvum oocysts. Calves were monitored for diarrhea during the first 45 days after birth; during each episode of diarrhea, fecal samples were examined for parasitic, bacterial, and viral pathogens. RESULTS: All 20 calves shed Giardia cysts and Cryptosporidium oocysts at some time during the study. Mean ages at which Giardia cysts and Cryptosporidium oocysts were first detected were 31.5 and 16.3 days, respectively. Mean number of Giardia cysts in feces remained high throughout the study, whereas Cryptosporidium occysts decreased to low or undetectable numbers 2 weeks after infection. Eighteen calves had a total of 38 episodes of diarrhea during the first 45 days after birth. Giardia duodenalis was the only pathogen identified during 6 (16%) episodes, C parvum was the only pathogen identified during 9 (24%) episodes, and G duodenalis and C parvum were identified together during 10 (26%) episodes. CONCLUSIONS: Prevalences of giardiosis and cryptosporidiosis were high in these calves, and both parasites were associated with development of diarrhea. Cryptosporidium parvum was an important pathogen when calves were < 1 month old, but G duodenalis was more important when calves were older. Calves cleared C parvum infections within 2 weeks; however, G duodenalis infections became chronic in these calves.     

Prophylactic use of decoquinate for infections with Cryptosporidium parvum in experimentally challenged neonatal calves

OBJECTIVE: To evaluate the effect of daily oral administration of decoquinate to neonatal calves experimentally challenged with various numbers of Cryptosporidium parvum oocysts. DESIGN: Clinical trial. ANIMALS: 75 calves. PROCEDURE: Calves were purchased from a commercial dairy during a 5-week period. Calves were housed in individual hutches and fed milk replacer with or without decoquinate (2 mg/kg [0.9 mg/lb per day]). Calves were randomly assigned to treatment and 1 of 5 challenge groups (0, 50, 100, 1000, or 10,000 C. parvum oocysts in 60 mL of saline [0.9% NaCl] solution administered p.o. on the day after arrival). Calves were maintained in the study for as long as 28 days. Calves were clinically assessed for diarrhea and dehydration. Fecal samples were submitted for oocyst enumeration 3 times each week. RESULTS: Treatment did not affect number of days to first watery feces (diarrhea), number of days to first oocyst shedding, or duration of diarrhea or oocyst shedding. Duration of oocyst shedding was significantly associated with challenge dose of oocysts administered to calves and number of days to first oocyst shedding. Duration of diarrhea and number of days to first oocyst shedding were significantly associated with week of arrival and number of days to first watery diarrhea. CONCLUSIONS AND CLINICAL RELEVANCE: Daily treatment with decoquinate at the dosage used in this study did not affect oocyst shedding or clinical signs associated with cryptosporidiosis. However, there was an indication that if the number of oocysts calves received could be reduced, then the duration of oocyst shedding and, hence, environmental loading of C. parvum oocysts could be reduced.     

Evaluation of fenbendazole for treatment of Giardia infection in cats concurrently infected with Cryptosporidium parvum

OBJECTIVE: To determine whether fenbendazole effectively eliminates Giardia organisms from chronically infected cats that have a concurrent Cryptosporidium parvum infection. ANIMALS: 16 clinically normal cats. PROCEDURE: Eight cats with chronic concurrent Giardia and C parvum infections received fenbendazole (50 mg/kg, PO, q 24 h) for 5 days (treatment-group cats). Feces from each cat were collected and processed 3 days weekly for 23 days after treatment. By use of an immunofluorescent assay for detection of Giardia lamblia cysts and C parvum oocysts, organism numbers were counted and scored. Fecal results from treatment-group cats were compared with those of 8 untreated cats with Giardia infection but no C parvum infection (control-group cats). RESULTS: Four of 8 treatment-group cats had consistently negative results for Giardia infection after treatment. These 4 cats had consistently positive results for C parvum oocysts prior to treatment and consistently negative results after treatment. One treatment-group cat had positive results for cysts on all fecal samples, and 3 treatment-group cats had 1 to 3 negative results and then resumed shedding large numbers of cysts; each of these cats had consistently positive results for C parvum oocysts. When compared with control-group cats, treatment-group cats shed less Giardia cysts during week 1 after treatment but not during week 2. CONCLUSIONS AND CLINICAL RELEVANCE: Administration of fenbendazole decreases Giardia cyst shedding to less than detectable numbers in some cats. In our study, persistent C parvum infection may have been associated with failure of fenbendazole to eliminate Giardia infection.     

The residual effect of treatment with ivermectin after experimental reinfection with nematodes in calves

The residual effect of treatment with ivermectin after experimental reinfection in calves was tested. Twenty-four calves were divided into 6 groups of 4 calves each. All calves received a primary infection of 50,000 larvae of both Ostertagia ostertagi and Cooperia oncophora and 1000 Dictyocaulus viviparus larvae. Calves of group 1 remained untreated, and all other calves were treated 21 days after primary infection (0.2 mg/kg injected subcutaneously). Calves of groups 1 and 2 were slaughtered 7 days later. Calves of groups 3-6 were reinfected with the same number of larvae 3 days, 1, 3 and 6 weeks after treatment respectively. Slaughter was 21 days after reinfection. Based on post-mortem worm counts the efficacy of ivermectin after primary infection was 99.7% for O. ostertagi, 95.1% for C. oncophora and 100% for D. viviparus. A residual effect was present for at least one week, but could not be observed 3 weeks after treatment.     

Exposure to pasture borne nematodes affects individual milk yield in Swedish dairy herds

Infections with the intestinal protozoan parasite Giardia in dogs and cats are common. Clinical signs vary from asymptomatic to small bowel diarrhea and associated discomfort. The control of infections in dogs is frequently a frustrating issue for animal owners and veterinarians. Drugs with antiprotozoal activity such as fenbendazole and metronidazole are recommended, however, they do not show 100% efficacy and superinfections occur regularly. Ronidazole is currently the drug of choice for the treatment of Tritrichomonas foetus in cats and there is now limited information available about its efficacy against Giardia spp. In the kennel investigated, dogs regularly showed loose feces and the presence of Giardia (assemblage C, renamed as G. canis) cysts. An elimination strategy of this parasite involving strict hygiene management and disinfection of the enclosures with 4-chlorine-M-cresol, oral treatment with ronidazole (30-50mg/kg BW bid for 7 days) and two shampooings (containing chlorhexidine) at the beginning and the end of the treatments was implemented for a group of 6 dogs. As a control another group of 7 dogs was transferred to the disinfected enclosures and shampooed, but left untreated. Dog feces were tested for the presence of Giardia cysts (SAF concentration technique) or Giardia antigen with a commercial ELISA (NOVITEC(?)) and a quick immunochromatography-based test (SensPERT(?)) before and between 5 and 40 days after the last treatment. All ronidazole-treated dogs were negative for Giardia cysts and antigen up to 26 days after the last treatment, while between 1 and 5 of the control animals tested positive in each of the test series. At this point, also dogs of the control group were again moved into clean enclosures, shampooed twice and treated with ronidazole. Five, 12 and 19 days after the last treatment, the dogs in the control group tested negative for Giardia cysts and antigen. However, all animals had again positive results at later time points in at least one of the three applied diagnostic techniques within 33-61 days after treatment. Furthermore, all dogs had episodes of diarrhea (for 1-4 days) within 14-31 days after treatment and unformed feces during the whole experiment. The positive effect of ronidazole against Giardia infections in dogs could be confirmed in this study. In particular, the combination of ronidazole treatment combined with the disinfection of the environment and shampooing of the dogs was highly effective in reducing Giardia cyst excretion and may therefore constitute an alternative control strategy for canine giardiosis.     

Efficacy of difloxacin in calves experimentally infected with Mannheimia haemolytica

OBJECTIVE: To determine the efficacy of difloxacin, a novel fluoroquinolone antibiotic, in calves experimentally infected with Mannheimia haemolytica (formerly Pasteurella haemolytica). ANIMALS: Seventy-two 3-month-old Holstein calves. PROCEDURES: Calves were inoculated with M haemolytica intratracheally; after they developed clinical signs of pneumonic pasteurellosis, they were randomly assigned to 1 of 6 groups (n = 12/group). Calves in each group were treated with 10% difloxacin (2.5 or 5 mg/kg of body weight), 5% difloxacin (2.5 or 5 mg/kg), enrofloxacin (5 mg/kg), or saline (0.9% NaCl) solution (control group), once daily for 5 days, and clinical signs were scored daily. On day 15, calves were euthanatized, and the percentage of diseased lung tissue was calculated. Swab specimens of the lungs were submitted for bacterial culture. RESULTS: Mortality rate and percentage of diseased lung tissue were significantly higher and cure rate and average daily gain were significantly lower for control calves, compared with calves in the treatment groups; however, no significant differences were found among treatment groups. Mannheimia haemolytica was isolated from the lungs of 10 control calves and from at least 2 calves in each of the treatment groups. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggest that difloxacin and enrofloxacin were equally effective for treatment of calves with experimentally induced pneumonic pasteurellosis. However, treatment of infected calves with difloxacin or enrofloxacin may not eliminate the organism.     

Diagnosis of Giardia infection in 14 calves

Fourteen calves, 12 days to 12 weeks old, were treated for diarrhea. Fecal examination for parasitologic, bacteriologic, or viral infection revealed Giardia in all calves; rotavirus and coronavirus were found in some calves. Thirteen affected calves were treated orally with dimetridazole (50 mg/kg of body weight, daily, for 5 days), with complete resolution of the diarrhea and elimination of the Giardia. Giardiasis should be considered as an etiologic agent of diarrhea in calves.     

Giardiasis in a cattery

Giardia sp infection was believed responsible for chronic, intermittent diarrhea in a group of 14 Persian cats. Seven of the cats were shedding Giardia sp cysts, and 6 of these cats had diarrhea at the time of fecal examination. Conversely, only 1 of 6 clinically normal cats in the group was shedding Giardia sp cysts. Cysts were not detected in feces of 2 cats with diarrhea. Cats less than or equal to 3 years old were more likely to be found shedding cysts. The parasite apparently was eradicated from the cattery by a combination of cage disinfection (1% sodium hypochlorite solution) and oral furazolidone treatment (4 mg/kg of body weight, BID for 5 consecutive days). During treatment, clinical signs resolved, and all cats remained clinically normal 2 months after treatment.     

Evaluation of flunixin meglumine as an adjunct treatment for diarrhea in dairy calves

OBJECTIVE: To assess the use of flunixin meglumine as an adjunct treatment for diarrhea in calves. DESIGN: Clinical trial. ANIMALS: 115 calves with diarrhea that were 1 to 21 days old at enrollment. PROCEDURE: Calves that developed diarrhea were randomly assigned to receive no flunixin meglumine (controls), a single dose of flunixin meglumine (2.2 mg/kg [1.0 mg/lb]), or 2 doses of flunixin meglumine administered 24 hours apart. Serum IgG concentration and PCV were measured prior to enrollment in the trial. Calves were evaluated daily to determine rectal temperature, fecal consistency, demeanor, and skin elasticity score. The primary analytic outcome was days of sickness (morbid-days). RESULTS: Calves with fecal blood and treated with a single dose of flunixin meglumine had fewer morbid-days and antimicrobial treatments, compared with controls. Although not significant, calves given 2 doses of flunixin meglumine in 24 hours had fewer morbid-days than untreated control calves. Regardless of severity of diarrhea, calves without fecal blood did not benefit from the use of flunixin. For calves with fecal blood, failure of passive transfer (low serum IgG concentration) was an independent risk factor for increased morbid-days. CONCLUSIONS AND CLINICAL RELEVANCE: Treatment with a single dose of flunixin meglumine resulted in fewer antimicrobial treatments and morbid-days in calves with fecal blood. As observed in other studies, calves with failure of passive transfer were at high risk for poor outcomes. This emphasizes the importance of developing and implementing effective colostrum delivery programs on dairy farms.     

No effect of bovine interferon-tau for control of calf diarrhea and immunomodulation in calves

Newborn calves received a low dose of bovine interferon-tau (boIFN-tau) orally for 4 weeks and calves that had developed diarrhea received a low dose of boIFN-tau orally for 5 days. No effects of boIFN-tau were seen in the duration of the diarrhea, or in daily weight gain. Calves received a high dose of boIFN-tau subcutaneously 3 times and they were then stimulated with bovine herpesvirus type 1 vaccine. No adverse effects were observed after the administration of boIFN-tau and lymphocyte subsets from calves did not change after the stimulation. Our results suggest that boIFN-tau does not seem protecting for preventing calves from diarrhea, recovering the health of calves with diarrhea or immunomodulation, although the treatment itself is not toxic.     

Efficacy of vaccination in preventing giardiasis in calves

The objective of this study was to evaluate the efficacy of a vaccine in the prevention of Giardia duodenalis infection in calves. Six 2-week old calves were vaccinated subcutaneously with a sonicated G. duodenalis trophozoite vaccine. Six 2-week old control calves received a subcutaneous injection of sterile phosphate-buffered-saline mixed with adjuvant. Injections were repeated after 28 days. Eleven days after the second injection, calves were challenged orally with 1x10(5) purified G. duodenalis cysts from a naturally infected calf. Throughout the study, fecal samples were collected at regular intervals and examined for the presence of G. duodenalis cysts. Blood samples were collected weekly until G. duodenalis challenge and bi-weekly following challenge. Calves were euthanized 14 days after challenge and G. duodenalis trophozoites within the small intestines were enumerated. Serum antibody titers were significantly higher in vaccinated compared to non-vaccinated calves. Vaccinated calves tended to excrete more G. duodenalis cysts in their feces than non-vaccinated calves. The number of trophozoites in the small intestine was not different between vaccinated and non-vaccinated calves. Changes consistent of moderate enteritis were found in the intestines of one vaccinated and one non-vaccinated calf. Despite a serological immune response following vaccination, this vaccine was not efficacious in preventing giardiasis or reducing cyst shedding in calves.     

Prevalence and infection pattern of naturally acquired giardiasis and cryptosporidiosis in range beef calves and their dams

The prevalence and infection pattern of naturally acquired giardiasis and cryptosporidiosis in 20 ranch raised beef calves and their dams from birth to weaning was determined. Rectal fecal samples were collected from calves at 3 days of age and weekly thereafter; cows' fecal samples were collected at the time of calving, 1 week later and four times during the summer grazing period. Blood samples were collected from the calves at 3 days of age to determine IgG(1) concentrations. Giardia lamblia cysts were shed by all 20 calves (100%) at some date during the duration of the study. However, only one calf (5%) shed Cryptosporidium parvum on two sample dates during the trial. Giardia cysts were first detected at 3.9+/-1.37 weeks of age with a range of 2-7 weeks of age. The geometric mean number of Giardia cysts in the calf feces increased from none at 1 week of age to a maximum of 2230 cysts/g of feces at 5 weeks of age and then decreased to 2 cysts/g at 25-27 weeks of age. Infection rate of calves shedding Giardia cysts peaked at 85% at 5 weeks of age and then decreased to 21% at 25-27 weeks of age. Giardia cysts, shed by calves peaked 1 week after initial shedding and decreased (P<0.05) for the remainder of the trial with the exception of week 3. There was a lower (P<0.05) percentage of calves shedding Giardia cysts weeks 3-10 and 15-25 compared to when shedding was first detected. All calves had complete or partial transfer of passive immunity as measured by IgG(1) levels. The rate of infection (15%) and the geometric mean number of Giardia cysts in the cows' feces (38.49 cysts/g) numerically increased at 1 week post-calving compared to levels at calving. The rate of infection (40%) numerically increased and the geometric mean number of Cryptosporidium andersoni oocysts in the cow feces (37.48 oocysts/g) increased (P<0.05) at 1 week post-calving and decreased to 0 at 13-16 weeks post-calving. This study is the first to document the cumulative prevalence and infection patterns of Giardia and Cryptosporidium in beef cattle under ranch conditions.     

Effect of treatment with levamisole or fenbendazole on primary experimental Dictyocaulus viviparus infection and on resistance in calves

Based on faecal larval counts, respiratory rates and live-weight gains, the anthelmintics levamisole and fenbendazole were equally efficacious against primary infection with Dictyocaulus viviparus in calves. Calves that were treated with levamisole or fenbendazole resisted the live-weight depressing impact of reinfection. Treatment somewhat impaired resistance to establishment of the secondary challenge as determined at necropsy. However, compared with previously uninfected controls, the treated animals harboured significantly fewer D viviparus, showing that they still strongly resisted reinfecting worms becoming established. The animal responses measured did not demonstrate any difference between levamisole and fenbendazole in relation to efficacy or to effect on resistance.     

Efficacy of florfenicol for treatment of naturally occurring infectious bovine keratoconjunctivitis

OBJECTIVE: To determine the efficacy of florfenicol for treatment of calves with naturally occurring infectious bovine keratoconjunctivitis (IBK). DESIGN: Randomized controlled field trial. ANIMALS: 63 beef calves and 80 dairy calves between 4 and 12 months of age. PROCEDURE: Calves were randomly assigned to 1 of 3 treatment groups. Calves in the SC treatment group received a single dose of florfenicol (40 mg/kg [18.2 mg/lb of body weight), SC, on day 0. Calves in the IM treatment group received florfenicol (20 mg/kg [9.1 mg/lb]), IM, on days 0 and 2. Calves in the control group received injections of saline solution (0.9% NaCl), IM, on days 0 and 2. Calves were reevaluated every other day for 20 days after treatment. RESULTS: Corneal ulcers healed by day 20 in 48 of 49 (98%) calves treated with florfenicol IM, 39 of 42 (93%) calves treated with florfenicol SC, and 33 of 52 (63%) control calves. CONCLUSIONS AND CLINICAL RELEVANCE: Florfenicol administered SC (1 dose) or IM (2 doses 48 hours apart) was effective for treatment of calves with naturally occurring IBK.     

Experimental infection of calves and sheep with bovine Giardia isolates

9 Giardia-free calves were artificially infected with 1.5-5.1 x 10(6) Giardia cysts originating from Swiss cattle ("bovine isolates"). In 4 of these animals the course of infection was examined. After prepatent periods of 7-8 days all calves excreted high numbers of Giardia cysts for 60-112 days. During patency on 44% of the examination days Giardia cysts and antigen could be detected simultaneously in faecal samples using the flotation method and a sandwich-ELISA, respectively. With the exception of light diarrhoea lasting only for some days at the beginning of patency no other symptoms occurred. Further 5 artificially infected calves were submitted to autopsy. Giardia trophozoites were detected in 4 calves in the jejunum and in 1 animal in the ileum (peroxidase-antiperoxidase method). All animals were simultaneously infected with Campylobacter spp. and/or Rota- and Corona-virus. Electronmicroscopically mucosal attachment sites of Giardia trophozoites had intact microvilli and enterocytes. In various parts of the intestine blunting and flattening of the villi and cellular infiltrations of the mucosa were present. These alterations in calves are generally associated with bacterial and/or viral infections of calves. A Swiss bovine Giardia cyst-isolate was transmitted to 4 Giardia-free conventionally maintained lambs which excreted Giardia cysts after prepatent periods of 10-21 days for 31-61 days.     

Giardia and Cryptosporidium in dairy calves in British Columbia.

A study was undertaken to determine the prevalence of Giardia infections in dairy calves and to compare Giardia and Cryptosporidium infections in calves of different ages. Fresh fecal samples were collected from 386 male and female Holstein calves (newborn to 24 wk) in 20 dairies located in the lower Fraser river valley area of British Columbia. Giardia intestinalis, Cryptosporidium parvum, and Cryptosporidium muris were enumerated in each sample after concentration by sucrose gradient centrifugation and immunofluorescent staining. Giardia was identified at all farm locations. The overall prevalence of Giardia in calves was 73% with a geometric mean cyst count of 1180 cysts per gram of feces (CI, 41 to 5014). Cryptosporidium parvum and C. muris were identified in 80% and 40% of the farms, respectively. The prevalence of C. parvum was 59%, and the geometric mean for oocysts was 457 oocysts per gram of feces (CI, 18 to 160). The prevalence of C. muris was only 2% and the mean oocyst counts were 54 oocysts per gram of feces. Giardiasis was not age dependent, and approximately 80% of the calves from 2 to 24 wk were infected. In contrast, C. parvum infections were predominant in calves 2 to 4 wk, while C. muris was demonstrated in calves older than 4 wk. Fourty-seven percent of calves with diarrhea had high numbers of Giardia cysts in their feces. Giardia infections are highly prevalent in dairy calves and should be considered in animals with diarrhea or failure to thrive.     

Field testing of a fenbendazole treatment combined with hygienic and management measures against a natural Giardia infection in calves

The need of a combination of animal treatment and environmental measures against a natural Giardia infection in calves between the age of 1 and 6 months was emphasized and evaluated. Ten commercial farms with a total of 94 calves suffering from chronic diarrhea, ill thriving and impaired growth, were included in two subsequent studies. The first study indicated that treatment of all animals with fenbendazole at 15 mg/kg during 3 consecutive days combined with environmental measures on the final day of treatment, which were either removal of bedding, thorough cleaning and ammonia 10% disinfection or relocation of the treated animals to a Giardia free environment, resulted in a total reduction in cyst excretion for at least 2 weeks. In the second study, the immunofluorescence assay (Merifluor Cryptosporidium/Giardia; Meridian Diagnostics Inc., Cincinnati, Ohio) was used quantitatively and confirmed that the combination of treatment and environmental measures resulted in a total reduction of cyst excretion during 2 weeks and in a significant (P<0.05; >or=98.0%) reduction of the cyst excretion until at least 4 weeks after treatment. Furthermore, there was a noticeable improvement of the clinical symptoms in all animals towards day 28 after treatment and 4 months after treatment health in all calves was normal.     

The efficacy of a Giardia lamblia vaccine in kittens.

Twenty kittens were vaccinated with a Giardia lamblia vaccine prepared on a commercial scale on day 0 and boosted on day 21 (group 1); while 10 kittens received only saline (group 2). These kittens were challenged on day 35 with 10(6) Giardia lamblia trophozoites by a surgical intraduodenal injection. Three control kittens were not vaccinated and not challenged (group 3). Following challenge, Giardia vaccinated kittens had significantly fewer days in which abnormal stools were observed and reduced food intake occurred compared to saline injected animals. The rate of weight gain between group 1 and group 2 animals was not different in the prechallenge period (day 0 to day 35), but vaccinated animals had a significantly higher weight gain in the postchallenge period (P < 0.05). On day 56, all vaccinated animals were not passing cysts in their feces, while 40% of saline injected kittens had Giardia cysts in their feces. In vaccinated kittens, cysts were never demonstrated in 45% of the animals, while cysts were detected in 90% of the saline injected kittens. Viability of the cysts in vaccinated kittens was 38% while the cysts viability in saline injected kittens was 99%. On postmortem examination, trophozoites could be detected in 5% of vaccinated kittens and 60% of saline injected kittens. Vaccination produced an elevated Giardia specific serum IgG and IgA response prior to challenge and throughout the postinfection period. The Giardia infection in the saline injected group did not induce an elevated specific serum response. Giardia vaccination of kittens provides protection in kittens from an experimental challenge by reducing or eliminating intestinal trophozoites and fecal cyst excretion.     

Efficacy of Giardia vaccination in the treatment of giardiasis in cats

OBJECTIVE: To assess efficacy of Giardia vaccination as a treatment for giardiasis in experimentally infected cats. DESIGN: Original study. ANIMALS: 16 young-adult cats. PROCEDURE: Cats were experimentally infected by orogastric administration of Giardia cysts. On weeks 4, 6, and 10, cats in the treatment group (n = 8) were given Giardia vaccine SC. For the first 28 weeks after infection, 3 fecal samples from each cat were examined weekly for Giardia cysts, and cyst numbers were counted. Fecal consistency was scored daily for the duration of the study. Results from vaccinated and unvaccinated cats were compared by logistic regression. RESULTS: All cats became infected and were shedding Giardia cysts by the end of week 2. Throughout the study, diarrhea was rare and was mild and transient when it did occur. By week 28, 5 of 8 vaccinated cats and 7 of 8 control cats had patent Giardia infections. Magnitude of infection, based on number of fecal samples with cysts and number of cysts per sample, decreased progressively in both groups over time. CONCLUSIONS AND CLINICAL RELEVANCE: Administration of 3 doses of a Giardia vaccine did not completely eliminate the organism from experimentally infected cats in the study period. Since clinical signs were minimal in both groups of cats, it could not be determined whether vaccination lessened severity of clinical disease. Results may have been negatively influenced by the large inoculation dose. Whether Giardia vaccination is an effective treatment for giardiasis in naturally infected cats remains to be determined.     

Effects of calcium disodium EDTA and meso-2,3-dimercaptosuccinic acid on tissue concentrations of lead for use in treatment of calves with experimentally induced lead toxicosis

OBJECTIVE: To compare the efficacy of calcium disodium EDTA (CaNa2EDTA) and meso-2,3-dimercaptosuccinic acid (DMSA) in reducing concentrations of lead in selected tissues for use in treatment of calves with experimentally induced lead toxicosis. ANIMALS: 19 sexually intact male Holstein calves that weighed 35 to 60 kg. PROCEDURE: Calves were randomly assigned to 1 of 5 treatment groups: group 1, control calves; group 2, lead only; group 3, lead and EDTA; group 4, lead and DMSA; and group 5, lead, EDTA, and DMSA. Calves in groups 2 to 5 were dosed daily with lead (5 mg/kg, PO) for 10 days. Doses of EDTA (100 mg/kg) and DMSA (25 mg/kg) were administered IV once daily for 4 consecutive days beginning on day 11. Effects of the chelators on lead concentrations in the liver, kidneys, testes, muscles, bones, and brain were compared among the various groups. RESULTS: Compared with the effects of EDTA, DMSA greatly reduced lead concentrations in renal and hepatic tissues. We did not detect significant differences for the effects of EDTA or DMSA on lead concentrations in the testes; there was an adverse interaction of EDTA with DMSA that caused an increase in lead concentrations in the testes. CONCLUSIONS AND CLINICAL RELEVANCE: DMSA is much more effective than EDTA in removing lead from renal and hepatic tissues in calves. Use of DMSA in calves with lead intoxication appears to be a viable treatment option. Combining DMSA and EDTA as a treatment modality in calves did not offer any advantages.