Book excerpt: This valuable PDA program presents an algorithmic approach to the differential diagnosis of multiple medical presentations commonly seen in daily veterinary practice. It allows users to look up signs, symptoms and laboratory abnormalities in a way that mimics the decision-making process of working toward a diagnosis. Each algorithm presumes that the first test performed has been a thorough history and physical examination, and from this point it relies on the use of clinical examination and diagnostic texts to progressively narrow a larger list of diagnoses for any given problem. The PDA version of this excellent resource is an easy and cost-effective way to quickly rule out possible conditions and arrive at a manageable list of differential diagnoses. The CD-ROM version of this handheld software is not Mac-compatible. All Mac users must purchase the downloadable version (ISBN 0-7216-0176-6). See link to this product under "Companion Products".