Congenital cataract in a Blackbelly lamb

Background: A cataract is an opacity of the crystalline structure that results in impaired vision. The congenital form manifests itself at birth or shortly thereafter and might also be inherited and therefore capable of passing on to descendants. Cataracts can be caused by systemic diseases, medications, toxic substances, radiation, metabolic alterations, dietary deficiencies, inflammation, traumatic injuries, age, or genetic factors. The few Blackbelly sheep herds are located in the northeast and north regions of Brazil and are considered rare, which could result in high levels of consanguinity. In this context, we report a case of congenital cataract in a Blackbelly lamb and its possible etiology. Case: A 3-month-old lamb presented with ophthalmic alterations since birth, with white and cloudy spots in both eyes and impaired vision. In the same herd, 3 elderly sheep showed similar ophthalmic alterations. The lamb was able to follow its dam, but when walking, bumped into small objects or very close to his vision field. The lamb managed to follow the herd and dodge large objects, suggesting partial vision loss. During a physical examination, both lens showed opacity and reduced corneal reflex, pupillary reflex to direct light, pupillary reflex to consensual light, and threat reflex. Ultrasonographic examination revealed that both lens presented hyperechogenicity. Hematological values were within the reference limits. In the same herd, three elderly sheep presented bilateral cataracts (2 rams and 1 ewe) in previous years, which at that time was attributed to natural aging. One ram was the lamb's grandfather. The other ram was the father of the female, both with cataracts. Based on history, physical examination, and complementary examinations, the lamb was diagnosed with bilateral congenital cataracts with a probable hereditary condition. Discussion: Multiple factors can be related to the etiology of cataracts, and it can be difficult to establish the correct etiology. Regarding the age of onset, cataracts can be classified mainly as congenital and senile. Senile cataract is a bilateral opacification process that involves the entire lens, with slow progression and gradual loss of vision with increasing age. In adult sheep, the high proportion of eyes affected by spontaneously arising cataracts could be related to age, increased exposure to sunlight, increased genetic susceptibility, or a combination of these factors. In this case, the herd had three adult elderly sheep with cataracts previously characterized as senile. However, after reviewing the genealogy, it was found that all animals had some degree of parentage, suggesting a hereditary factor. Congenital cataracts are expressed soon after birth, resulting from the malformation of fibers in the lens, and are generally nonprogressive. The congenital form may or may not be associated with hereditary factors. Inheritance cataracts have been reported in several breeds of dogs and usually occur as an autosomal recessive trait. Blackbelly sheep are rare in Brazil, favoring consanguinity, so we believe that cataracts are inherited in this herd. To control this ophthalmic alteration, all animals with crystalline opacities were excluded from reproduction, and the herd should be monitored in future cases.

Susceptibility of the horn fly, Haematobia irritans irritans (Diptera: Muscidae), to insecticides in Brazil / Suscetibilidade da mosca-dos-chifres, Haematobia irritans irritans (Diptera: Muscidae), a inseticidas no Brasil

Since horn fly populations became established throughout Brazil, complaints regarding control failure have increased around the country. A broad survey to evaluate the susceptibility of horn flies to both organophosphate (OP) and pyrethroid insecticides was conducted from October 2000 to April 2003. Bioassays using filter papers impregnated with cypermethrin, permethrin or diazinon were conducted on 154 horn fly populations in 14 states and 78 municipalities. Resistance to cypermethrin, the active ingredient present in most insecticide products for horn fly control in Brazil, was detected in 98.46% of the populations, with resistance ratios (RR) ranging from 2.5 to 719.9. Resistance to permethrin (RRs < 6.3) was found in 96.67% of the populations, despite its lack of use. In general, pyrethroid resistance was detected in 97.18% of the horn fly populations, with frequencies greater than 87% in all regions of the country. The status of susceptibility of horn fly populations in Brazil to insecticides can be characterized by high susceptibility to OPs and widespread resistance to pyrethroids, potentially compromising the efficacy of pyrethroid products in most cases. Although some partial results have previously been presented, a general picture of horn fly susceptibility in Brazil is presented here for the first time.(AU)

Desde a dispersão da mosca-dos-chifres, no Brasil, queixas sobre seu controle aumentaram em todo o país. Um amplo levantamento objetivando avaliar a suscetibilidade da mosca a inseticidas organofosforados (OF) e piretróides foi realizado de outubro de 2000 a abril de 2003. Bioensaios com papéis de filtro impregnados com cipermetrina, permetrina ou diazinon foram conduzidos em 154 populações da mosca-dos-chifres de 14 Estados e 78 municípios. Resistência à cipermetrina, ingrediente ativo presente na maioria dos produtos para controle da mosca-dos-chifres no Brasil, foi detectada em 98,46% das populações, com fatores de resistência (FR) variando de 2,5 a 719,9. Resistência à permetrina (FR < 6,3) foi encontrada em 96,67% das populações testadas, apesar da falta de uso de produtos contendo este princípio ativo. Em geral, resistência a piretróides foi detectada em 97,18% das populações, com frequências acima de 87% em todas as regiões do país. A situação da suscetibilidade da mosca-dos-chifres a inseticidas, no Brasil, pode ser caracterizada por uma elevada suscetibilidade aos organofosforados e ocorrência generalizada de resistência aos piretróides, potencialmente comprometendo a eficácia desses produtos na maioria dos casos. Embora resultados parciais tenham sido apresentados anteriormente, um quadro geral da suscetibilidade da mosca-dos-chifres no Brasil é apresentado pela primeira vez.(AU)