Final answer:
The condition with symptoms of weight loss, quidding, halitosis, swelling, and nasal discharge in equines is likely a tooth root abscess, which can be confirmed through examination and X-rays.
Step-by-step explanation:
The condition in equines that involves signs like weight loss, quidding, halitosis, swelling, and nasal discharge is most consistent with tooth root abscess. This condition is different from equine influenza, which primarily causes respiratory signs without the oral/dental symptoms described. It is also distinct from laminitis, a condition affecting the hooves. Periodontal disease could account for some of the symptoms, such as halitosis and swelling, but a tooth root abscess specifically can lead to more severe symptoms including quidding, when a horse drops food from its mouth because of dental pain, and nasal discharge, if the infection becomes serious enough. A tooth root abscess can cause erosion of the gums and cementum, leading to tooth loss in advanced infections. Diagnosis typically involves visual examination and can be confirmed with X-rays.