title: Nitric oxide metabolites in naturally occurring canine babesiosis.
abstract: Babesiosis, caused by the virulent haemoprotozoan parasite Babesia canis rossi, is an important disease of dogs in South Africa. The nitric oxide metabolites, nitrate and nitrite (collectively termed reactive nitrogen intermediates or RNIs) were measured in admission sera from dogs in a babesiosis-endemic area. Five groups were prospectively studied: mild uncomplicated (n=9), severe uncomplicated (severe anaemia) (n=10) and complicated babesiosis (n=11); and two groups of healthy aparasitaemic dogs: endemic controls from the study area (n=10) and experimental dogs kept in tick-free conditions (n=10). Four measures of RNI production were studied: (i) serum RNI; (ii) serum RNI/creatinine ratio; (iii) fractional clearance of RNI (FC(RNI)); (iv) fractional excretion of RNI (FE(RNI)). Marked elevations of serum RNI occurred in only two dogs, both in the severe uncomplicated group. The highest concentration (log value 5.29 micromol/l) was in a dog that died, but concentrations in the other four dogs that died were unremarkable (0, 0.34, 1.66 and 2.64 micromol/l). Age, appetite and free serum haemoglobin were significant covariates for measures of RNI production. There were no significant differences among the babesiosis groups for serum RNI. Adjustment for creatinine had minor effects on the results. All babesiosis groups had significantly higher serum RNI and RNI/creatinine than the tick-free control group, but did not differ from the endemic controls except for the severe uncomplicated group, which had higher RNI/creatinine. The complicated group had significantly lower FC(RNI) and FE(RNI) than all other groups, except for the tick-free control group, which had similar FE(RNI). The results indicate that, in an endemic area, measures of RNI production are unlikely to be useful indicators of severity or outcome in canine babesiosis.
authors.affiliation: Faculty of Veterinary Science, Department of Companion Animal Clinical Studies, University of Pretoria, Private Bag X04, Onderstepoort 0110, South Africa. linda@frcs.alt.za
authors.forename: Linda S
authors.initials: LS
authors.lastname: Jacobson
authors.forename: Remo G
authors.initials: RG
authors.lastname: Lobetti
authors.forename: Pieter
authors.initials: P
authors.lastname: Becker
authors.forename: Fred
authors.initials: F
authors.lastname: Reyers
authors.forename: Tarquin
authors.initials: T
authors.lastname: Vaughan-Scott
mesh_terms: D000818:Animals; D001403:Babesia / Q000254:growth & development*; D001404:Babesiosis / Q000097:blood / Q000652:urine / Q000662:veterinary*; D003404:Creatinine / Q000652:urine; D004283:Dog Diseases / Q000097:blood / Q000469:parasitology* / Q000652:urine; D004285:Dogs; D005260:Female; D008297:Male; D009569:Nitric Oxide / Q000096:biosynthesis / Q000378:metabolism*; D018512:Parasitemia / Q000662:veterinary; D011446:Prospective Studies; D026361:Reactive Nitrogen Species / Q000096:biosynthesis; D013019:South Africa
chemical_list: D026361:Reactive Nitrogen Species; D009569:Nitric Oxide; D003404:Creatinine