Adult heartworms (HWs) were found in the lungs of 5% of 630 necropsied adult cats from an animal shelter in Florida. Male cats were at slightly increased risk of harboring HWs compared to female cats. There was no association between HW infection and co-infection with FeLV or FIV. The performance of 6 different HW antigen and antibody tests revealed a wide disparity in diagnostic accuracy among the various tests, and not all cats with HWs found at necropsy were seropositive for HW antigen or antibody.

Using the finding of adult worms at necropsy as the gold standard, antigen tests had a sensitivity of 68-86% and a specificity of 98-99%. Antibody tests had a sensitivity of 32-90% and a specificity of 78-99%. Nine of 31 cats with HWs found at necropsy (29%) had at least 1 false-negative antigen test and 4 cats (13%) were negative on all antigen tests. Twenty-one cats (68%) had at least 1 false-negative antibody test, and 2 cats (6%) were negative on all antibody tests. Thus, testing protocols that eliminate the possibility of HW infection in a cat, based on a negative HW antibody test, may be inaccurate. For cats with HW infection as a differential diagnosis, the preferred initial screening workup includes both HW antigen and antibody testing and a chest radiograph. An echocardiogram is included if the index of suspicion is high. Because even a single worm can cause disease or death, HW preventive is appropriate for all cats living in high-risk exposure regions.

Reference: Levy. Proc. ACVIM Forum, 2004

Giardia in cats can be difficult to manage medically. Currently available treatments are sometimes toxic (metronidazole; albendazole) or have < 100% efficacy (fenbendazole). The combination of febantel/pyrantel/praziquantel (Drontal Plus®, Bayer Animal Health) has been effective for treating Giardia infection in some dogs and is known to be safe when given to cats.

Febantel/pyrantel/praziquantel was evaluated as a treatment for giardiasis in experimentally-inoculated cats. Feces from each cat were collected daily and analyzed for the presence and number of Giardia cysts using a commercially available direct immunofluorescence test (Meridian Diagnostics, Cincinnati, OH). In Experiment 1, 5 infected cats were administered febantel/pyrantel/praziquantel at the dose of 1 small dog tablet/cat, PO, for 5 d and 4 infected cats were used as untreated controls. In Experiment 2, 6 infected cats were administered febantel/pyrantel/praziquantel at the dose of 2 small dog tablets/cat, PO, for 5 d and 5 infected cats were used as untreated controls. All cats testing negative for Giardia cysts on d 18 after the beginning of therapy were administered 20 mg/kg methylprednisolone acetate, IM weekly for 2 injections.

Treated cats in Experiment 1 had less positive samples (p < 0.05) and shed less cysts (p < 0.05) than untreated cats, but Giardia infection was maintained. Treated cats in Experiment 2 had less positive samples (p < 0.05) and shed less cysts (p < 0.05) than untreated cats, and Giardia infection was apparently eliminated in 4 of 6 treated cats even after attempted immunosuppression. Drug toxicity was not noted in either experiment.

Based on these results, the administration of 2 small dog tablets/cat of the febantel/pyrantel/praziquantel combination PO for 5 d may be an effective treatment of Giardia infection in some cats. Note that the study used a specific strain of Giardia and so field strains may not respond similarly.

Reference: Scorza, Radecki, Lappin. Proc. ACVIM Forum, 2004