Hello and thanks for trusting me to help you and Coco today. I am a veterinarian with over 25 years experience and would be happy work with you.
It definitely sounds as if Coco needs to have a thorough physical exam performed by your veterinarian. There are very many reasons why cats vomit, some more serious than others. Vomiting is a vague sign that can be associated with simple things like dietary indiscretion to more serious things like intestinal obstruction or metabolic disorders. In young cats, we usually are a little more worried about foreign body ingestion. We decide how aggressive we need to be in diagnosing and treating it based on how severe the symptoms and how long it has been going on.
In her case, since the vomiting is associated with weight loss, I would be most worried about the cause of the problem being located in the GI tract itself. Many cats have a low grade chronic pancreatitis which can be a challenge to confirm as it is not always evident on routine bloodwork. Along with that, many of these same cats also have a degree of inflammatory bowel disease (IBD) or intestinal cancer. Unfortunately, either of these can be present and there can be no other abnormalities noted on bloodwork, xray or even ultrasound but that is always where we start when working up causes of vomiting and diarrhea. It is best to rule out the easy to rule out things first before getting more aggressive with diagnostics. An overactive thyroid gland can be another cause of weight loss in cats and is usually diagnosed easily via a blood test.
When dealing with disease of the GI tract, it is usually not a critical what they are eating (unless it is a food allergy problem), when we are trying to control the symptoms and get them to gain weight. It becomes more important to identify the cause and treat that if we want to alleviate the symptoms.
I would urge you to schedule an appointment with your veterinarian soon. After a thorough exam of Coco, they will be better able to advise you of what further diagnostics may be needed.
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