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  • Author or Editor: Yung-Fu Chang x
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Objective—To identify risk factors associated with Cryptosporidium parvum infection in dairy calves.

Animals—108 case animals and 283 control animals.

Procedures—Case animals were calves infected with C parvum, and controls were infected with Cryptosporidium bovis (n = 67) or calves not infected with Cryptosporidium spp. Fecal samples were tested via the flotation concentration method for Cryptosporidium spp. Samples were genotyped by sequencing of the 18s rRNA gene. Associations between host, management, geographic, and meteorologic factors and Cryptosporidium genotype were assessed.

Results—Younger calves and calves housed in a cow barn were more likely to be infected with both genotypes. Herd size and hay bedding were associated with an increased risk of infection with C parvum, and Jersey breed was a risk factor for C bovis infection. Compared with a flat surface, a steeper slope was significantly associated with a decreased likelihood of infection with both genotypes, and precipitation influenced the risk of C parvum infection only.

Conclusions and Clinical Relevance—Risk factors for calf infection with C parvum differed from those for infection with C bovis. Results may be useful to help design measures that reduce animal exposure and decrease public health risk and economic losses associated with C parvum infection in cattle.

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in American Journal of Veterinary Research


Objective—To develop a method to experimentally induce Borrelia burgdorferi infection in young adult dogs.

Animals—22 healthy Beagles.

Procedure—All dogs were verified to be free of borreliosis. Twenty 6-month-old dogs were exposed to Borrelia burgdorferi-infected adult ticks and treated with dexamethasone for 5 consecutive days. Two dogs not exposed to ticks were treated with dexamethasone and served as negative-control dogs. Clinical signs, results of microbial culture and polymerase chain reaction (PCR) testing, immunologic responses, and gross and histologic lesions were evaluated 9 months after tick exposure.

Results—Predominant clinical signs were episodic pyrexia and lameness in 12 of 20 dogs. Infection with B burgdorferi was detected in microbial cultures of skin biopsy specimens and various tissues obtained during necropsy in 19 of 20 dogs and in all 20 dogs by use of a PCR assay. All 20 exposed dogs seroconverted and developed chronic nonsuppurative arthritis. Three dogs also developed mild focal meningitis, 1 dog developed mild focal encephalitis, and 18 dogs developed perineuritis or rare neuritis. Control dogs were seronegative, had negative results for microbial culture and PCR testing, and did not develop lesions.

Conclusions and Clinical Relevance—Use of this technique successfully induced borreliosis in young dogs. Dogs with experimentally induced borreliosis may be useful in evaluating vaccines, chemotherapeutic agents, and the pathogenesis of borreliosisinduced arthritis. (Am J Vet Res 2001;62:1104–1112)

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in American Journal of Veterinary Research