Lab Flash
Dr Rick Last – BVSc , M . Med . Vet ( Pathology ) Specialist Veterinary Pathologist
Urgent Alert – Bacteriology Sampling Procedure
Over the past few months we have noted a dramatic increase in the submission of multiple fresh organs mixed in a single container for bacteriological culture . We implore you to please refrain from utilizing this technique , as submission of multiple organs in a single container , severely compromises the bacteriological cultures and frequently results in cross-contamination with important bacterial pathogens being overgrown by contaminants or environmental organisms . This results in misdiagnosis . Always ensure that individual organs are placed in individual containers , or even better collect charcoal swabs from each individual organ . The charcoal medium ensures prolonged survival of bacterial pathogens and allows for culturing for aerobic bacteria , anaerobic bacteria and fungal pathogens .
Demodecosis in a Cat
We were presented with skin biopsies from a cat in 10 % buffered formalin . This 4 year old , male , domestic shorthair cat , had developed a chronic crusting lesion on the nasal planum as well as generalized dry sebborhea . The nasal biopsies revealed severe parakeratosis with numerous Malassezia yeasts within the surface crust , associated with marked epidermal acanthosis and hyperplasia with multiple intra follicular Demodex cati parasites identified in hair follicles . The skin biopsies collected from multiple cutaneous sites revealed surface orthokeratotic hyperkeratosis with numerous surface keratin Demodex gatoimites identified .
Feline demodecosis may be caused by 2 species of Demodex sp namely ; D . cati and D . gatoi . D . cati is similar to canine Demodex with mites living in the hair follicles , D . gatoi on the other hand is a stubbier mite and resides in the stratum corneum . Demodecosis in cats can be focal , often on the face , or generalized . Lesions vary from scaly erythematous patches with alopecia to miliary dermatitis . Symmetrical alopecia without skin lesions and focal areas of alopecia with some resemblance to dermatophytosis , have also been described . Ceruminous otitis externa has also been associated with demodex . Pruritis is variable in infections caused by D . cati , but D . gatoi tends to be extremely pruritic . Immunosuppressive diseases ( viral infections , diabetes mellitus , cushings , SLE ) and corticosteroids can predispose to generalised demodecosis . It is unusual to find both parasites in the same cat , as noted in this case .
Severe Coccidiosis in Impala
A group of impala lambs ( 4 to 5 months of age ) were bought on an auction and translocated to the buyer ’ s farm . The animals were off loaded in a small 2 ha – 3ha camp natural veld ( grass thorn trees ) and given lucern mix ration . The first animal was found dead 7 days after arrival , the 2nd after 10 days and 3rd after 2 weeks . On
2018 MAY 19