Hypo-osmotic test in cat spermatozoa.

The hypo-osmotic (HOS) test has been used in other species as an indicator of the fertilising capacity of spermatozoa. The aims of this study were to assess the response of domestic cat spermatozoa to the hypo-osmotic test, to determine the type of solution, concentration and time of incubation needed to obtain a maximum percentage of swelling, to correlate the selected combination with the percentages of progressive motility and to evaluate whether dilution of the ejaculate alters the results. Incubation for 30 and 45 min in solutions of fructose and of citrate of 50 and 100 mOsmol kg⁻¹ was evaluated. The highest percentage of swelling was obtained using the 50 mOsmol kg⁻¹ solution, and no significant differences were observed between the times of exposure to the solutions. A positive correlation was observed between the percentage of individual progressive motility and the percentage of sperm swelling in a 50 mOsmol kg⁻¹ fructose solution, with no significant differences being observed between raw and diluted semen samples. The results of this study suggest that the HOS test could be useful for evaluating membrane function in domestic cat spermatozoa, both in raw semen and in samples diluted in the EZ Mixin® commercial extender, and thus could be incorporated into routine semen evaluation protocols.

Preliminary study of an immunochromatography test for serological diagnosis of canine brucellosis.

The most widely used screening test for the diagnosis of brucellosis in the dog is the rapid slide agglutination test in the presence of 2-mercaptoethanol (2ME-RSAT). The diagnosis is partially confirmed by the agar gel immunodiffusion test (AGID) and definitively confirmed by bacteriological isolation. Some chronic cases not detected by these tests may be detected by ELISA tests. The use of 2ME-RSAT in routine clinical practice requires a microscope and an experienced operator. An immunochromatographic diagnostic test for canine brucellosis (FASTest(®) Brucella c., Megacor, Hörbranz, Austria) has been recently released. In this study, we compared the diagnostic performance of the FASTest with those of 2ME-RSAT, AGID and ELISAs. Sera from 17 healthy dogs used as negative controls yielded negative results by FASTest, indicating a 100% specificity in this sample. Among 27 sera of dogs with acute or subacute brucellosis confirmed by B. canis isolation, all of which were positive by RSAT and ELISAs, the FASTest was positive in 24 cases and AGID in 23. In acute and subacute cases, the sensitivity of FASTest was 89%. Sera from six dogs with bacteriologically confirmed chronic brucellosis, which were positive by ELISAs but negative by 2ME-RSAT, were also tested; 1 was positive by FASTest and 4 were positive by AGID. These preliminary results indicate a good specificity of the FASTest (100% in this sample) but an unacceptable sensitivity as a screening test. In cases with chronic brucellosis, the sensitivity of the FASTest was lower than that of ELISAs but this assay could make a good intermediate test to be run after a positive RSAT and before running an AGID.

Diagnosis of canine brucellosis by detection of serum antibodies against an 18 kDa cytoplasmic protein of Brucella spp.

An antigenic capture ELISA was developed to measure serum antibodies against an 18 kDa cytoplasmic protein of Brucella. This assay was used to detect anti-18 kDa reactivity in sera from 30 dogs having confirmed or suspected brucellosis. Antibodies against the 18 kDa protein were found in 26 of them, which were also positive by the slide agglutination test (2ME-RSAT). The overall correlation (positive and negative results) between the ELISA and 2ME-RSAT tests was 93.3%. Additionally, these sera were assayed by an indirect ELISA using a whole extract of cytoplasmic proteins of B. abortus (LPS-free CYT). The results of both ELISAs were coincident in 28 of 30 (93.3%) dogs having confirmed or suspected brucellosis. When a serological follow-up was performed on some dogs having confirmed brucellosis, antibody titers measured by both ELISAs showed a parallel progression. On the other hand, the capture ELISA showed good specificity, since a positive result was obtained only in 2 of 103 sera from healthy dogs. These preliminary results show that the ELISA for detecting serum antibodies against the 18 kDa cytoplasmic protein of Brucella could be useful for the diagnosis of canine brucellosis. This study also shows that the results obtained with this single protein of Brucella are equivalent to those obtained with the whole extract of cytoplasmic proteins.

Clinical use of dexamethasone for termination of unwanted pregnancy in dogs.

Dexamethasone was administered orally for 7.5 or 9.5 days to 80 pregnant bitches to terminate unwanted pregnancy at an outpatient clinic. Treatment was initiated at day 30-35 (n = 74) or day 45-50 (n = 6) of confirmed pregnancy using one of two dosages. In 62 bitches, dexamethasone was administered twice a day for 7.5 days increasing from 0.1 to 0.2 mg kg-1 over the first 2 days of administration and decreasing from 0.16 to 0.02 mg kg-1 over the last five administrations. The 18 remaining bitches were given dexamethasone twice a day for 9.5 days, at a dosage of 0.2 mg kg-1 for 7 days and then decreasing from 0.16 to 0.02 mg kg-1 over the last five administrations. Pregnancy was terminated without complication in 75 of the 80 bitches, and uterine contents were absorbed or aborted or both. Pregnancy was not terminated in five bitches treated for 7.5 days beginning at day 30-35 of gestation. In four of them parturition occurred at the normal time; in one, pregnancy was terminated by a second treatment. Pregnancy termination occurred at 7-15 days after the start of treatment. During ultrasonographic imaging of 13 bitches treated with dexamethasone, fetal deaths occurred between 5 and 13 days after the start of treatment. The side effects reported by the owners included polydipsia and polyuria, which were observed in all of the bitches and which disappeared when the treatment was discontinued. Some bitches also experienced vaginal discharge, restlessness, anorexia or emesis. At the first or second cycle after treatment, 20 bitches were mated and had normal pregnancies and normal litters. The results suggest that oral treatment with dexamethasone can be used to terminate pregnancy in bitches, but that in some cases the withdrawal of treatment after 8 days can result in retention of live pups and require a further treatment or the use of another abortifacient.