PSX-30 - Scratching the surface: Investigating the nature and potential causes of pruritic cattle

Abstract: Depending on the year, during the winter months, cattle begin to rub bare patches on their skin due to pruritus which leads to concern from cattle produces, especially the purebred breeders. Upon further investigation by veterinarians, the cause is not always caused by lice, as many may think. This study aimed to provide insight into the cause and potential prevention/treatment of pruritic beef cattle in Western Canada by examining herds that met the study’s criteria of having more than 30% of the herd exhibiting pruritus. Seven herds were examined in the winter of 2023: one from Manitoba, two from Saskatchewan, and four from Alberta. Producers from each herd completed a detailed survey on treatments, nutrition, and environmental conditions and provided feed, water, and bedding samples. Within each herd, five cattle considered non-pruritic, and ten cattle considered pruritic by visual appraisal were enrolled for standard data collection consisting of documentation and photos of skin lesions localized to pruritic areas, general health clinical exam, lice exam/collection, mite exam/collection of hairs, skin hydration (corneometer), blood chemistry and vitamin/minerals, and kidney/liver enzymes for mycotoxins. A subset of the group (1 non-pruritic and 4 pruritic) was selected for advanced data collection, including dermal hypersensitivity (grass, alfalfa, grain, weeds, and molds) measured by swelling score and infrared camera temperature measurement compared to positive and negative controls, skin punch biopsies for eosinophils (IgE) and liver biopsies for copper levels. Only 21/101 cattle had lice (18 head < 10 lice per 6.5 cm 2). No significant correlation was observed between cattle with lice and being pruritic (P>0.05). Dermal hypersensitivity was very low across both pruritic and non-pruritic cattle and was not significantly different (P>0.05). Skin hydration readings within animals comparing pruritic and non-pruritic areas on their body showed only one herd having significantly (P <0.05) drier skin on pruritic locations compared to normal locations. Vitamin A, E, and copper blood analysis showed no significant difference between pruritic and non-pruritic cattle. However, liver biopsy copper levels were significantly (P=0.01) lower in pruritic versus non-pruritic cattle. Results suggest that the cause of pruritic cattle is not necessarily a result of intense lice infestations but rather multifactorial in nature, and a decision tree for producers and veterinarians should be developed to aid in determining the correct course of action to alleviate pruritic cattle in the field.