Evaluation of Long-Term Effects of the Gonadotrophin-Releasing-Hormone Antagonist Acyline on Domestic-Cat Growth.

Acyline contraception has been described in cats, but few data are available on the drug's long-term effect on growth. The relevant data cover until puberty with no radiographic description. We investigated the radiographic parameters throughout bone growth in order to more completely determine the drug's safety. Thirteen male and 12 female cats were studied, with the kittens being randomly assigned to one of the following groups within the first 24 hours of birth: ACY, subcutaneous acyline, 33 µg/100 g, which injection was repeated weekly until age 3 months; or CO, untreated control. Body measurements were recorded weekly and radiographic parameters obtained from monthly radiographs of the antebrachium. In the ACY and CO male and female kittens, the body weight, withers height, and body length plus the age at the end of body growth and radial growth remained similar throughout the study (P> .05). Both female groups finished radial growth before the males (P< .05). The ACY females evidenced a longer radial length between the eighth and 28th weeks (P< .05). All groups closed their proximal and distal physes within the normal ranges described for the species. The bone-cortex width was lower in the ACY vs. the CO animals at weeks 52 and 60 in the males and at weeks 24, 48, 52, and 56 in the females (P< .05) The transient greater radial length and lower bone-cortex thickness observed in the treated cats were compensated for at the end of growth with no adverse clinical effects being observed. In conclusion, acyline as a contraceptive did not evidence a permanent or severe effect on domestic-cat growth.

Vaccination of domestic animals with a novel oral vaccine prevents Giardia infections, alleviates signs of giardiasis and reduces transmission to humans.

Giardia lamblia is a human intestinal parasite and one of the most frequent enteric pathogen of companion animals. Clinical manifestations of giardiasis, such as diarrhoea, anorexia, weight loss and lethargy, have been associated with Giardia infections in both domestic and farm animals. A few anti-parasitic drugs are routinely used to treat giardiasis, but re-infections are common and drug-resistant strains have already been reported. Unfortunately, efficient vaccines against Giardia are not available. Giardia undergoes antigenic variation; through this mechanism, parasites can avoid the host's immune defenses, causing chronic infections and/or re-infections. Antigenic variation is characterised by a continuous switch in the expression of members of a homologous family of genes encoding surface antigens. In a previous report, we indicated that in Giardia, the mechanism responsible for the exchange of variant-specific surface proteins (VSPs) involves the RNA interference (RNAi) pathway. From a repertoire of ~200 VSP genes, only one is expressed on the surface of single trophozoites; however, RNAi machinery disruption generates trophozoites that express the complete VSP repertoire. We also demonstrated that gerbils orally immunised with VSPs isolated from these altered parasites showed high levels of protection. Here we tested this vaccine in cats and dogs, and found that it is highly efficient in preventing new infections and reducing chronic giardiasis in domestic animals both in experimental and natural infections. Remarkably, immunisation of dogs in a highly endemic area strongly decreased the percentage of infected children in the community, suggesting that this vaccine would block the zoonotic transmission of the disease.