This section is on feline internal medicine topics. These are all questions that have been submitted or that I have been inspired to talk about because of a question submitted. If you have any topics that you would like to have discussed please feel free to email me with the topic or question.

Why are male cats more prone to urinary tract obstruction than female cats?

Urinary tract obstruction in cats can occur from a variety of substances. The two most common are stones and proteinaceous plugs. Stones are formed by mineral depositions. High mineral diets contribute to this problem. Oxalate (a calcium crystal) and struvite (a magnesium crystal) are the two most common types of stones. No one is really sure what causes proteinaceous plugs to form. These plugs are comprised of amorphous proteins that clump together to form a plug. The stones or the plug lodge in the urethra (the tube that leads from the bladder to the outside world) preventing the passage of urine out of the bladder. Males due to their anatomy have narrower urethras than females do. Thus, it takes less material to block a male's urethra than a female's. This is true in cats as well as most other species.

My older cat has become very anxious lately. She has stopped grooming herself properly and, although she seems to eat everything we offer her, she is losing weight. Is this just a part of cat aging, or something we need to worry about?

What you cat is experiencing is not uncommon in older cats. Her signs -- anxiousness, poor grooming, weight loss in the face of a normal or increased appetitie -- are typical of hyperthyroidism. Hyperthyroidism is a disease caused by an increase in the amount of thyroid hormone, or thyroxine, produced and circulating in the bloodstream. Thyroid neoplasia is the most common cause of this condition. Thyroxine is responsible for regulating metabolism as well as influencing a variety of other functions. Excess amounts of thyroxine results in an abnormally increased metabolic rate (hence, the weight loss). Other signs include abnormally increased activity; behavioral changes including hyperactivity, nervousness, and aggression; and poor grooming. Many older cats are affected by this and medical and surgical treatments exists. Many veterinary facilities today can perform radioactive iodine therapy. Iodine is almost exclusively taken up by the thyroid gland. By using radioactive iodine, the thyroid tissue that has become cancerous is selectively destroyed with relatively few side effects. From the description that you have given one of the likely causes is hyperthyroidism. But there are other causes of these signs. Please make an appointment with your veterinarian and have your cat examined.

Why do you have to be careful in how fast a cat loses weight?

When a cat diets (or humans for that matter) its body is put into a state of mild starvation so that it will use up the fat it has stored. In using up this fat, the fat is broken down and sent to the liver for processing. Certain cats when they experieince a sudden, drastic drop in caloric intake mobilize massive amounts of fats. All these fats get sent to the liver. In the liver, the fats take up so much room that they interfere with the normal function of the liver. Thus, the cat experiences signs of liver decline -- one of which is anorexia. So the caloric intake is further decreased, more fats are mobilized,and the vicious circle starts. These cats must be given food even if it via a stomach tube in order to reverse the condition. If not treated, the cat will die. Therefore, it is imperative to do slow and steady caloric decreases rather than one huge one.

I have a question regarding my cat "Mocha". She has started to vomit 3 weeks ago , 3 times for a period of one week. The vomit contained indigested food only and seemed very dry. For two week everything was fine, and today it started again, she actually vomited twice in a row this morning, again indigested food. She still acts as lively as ever, she eats and drinks normally, and she has regular bowel movement. I do feed her Hill's t/d feline prescription diet, which was reommended by my vet and a bit of nutrience for adult cats. She is an indoor cat and has had her Leukemia shot back in dec along with rabies and fvrcp shots, she will be 2 years in April. Any comments or suggestions? I am quite worried thanks a lot in advance for your help.

Vomiting in cats is a very hard thing to diagnose a cause for. Just about anything from hairballs to heartworms to kidney disease to neoplasia can be a cause. If you think it is not just the typical hairball vomiting then my best advice is to take her in and let your veterinarian pull some blood for analysis. Is she on heartworm preventative? If not I would recommend a heartworm test. The number one presentation of cats with heartworms is vomiting. Based on the bloodwork, your veterinarian can narrow the possibilities down and pursue an exact cause. The fact she is acting normally, eating and drinking normally, etc all suggest it is not a problem with liver/kidneys or cancer. But you cannot completely rule those out as possibilities. Bloodwork would give a better idea regarding that. Another possibility is that she is regurgitating instead of vomiting. This is likely given that it is undigested food. Regurgitation is indicative of a problem with the esophagus. So, I apologize but I don't have an answer for you other than take her to your vet if you consider it to be more serious that the occasional hairball vomiting.

I was just reading your answer to the question about the correct diet for a cat with urinary tract problems. We have a cat that is 8 years old, he has had bladder stones removed three times in the past five years. I know after the second surgery they found out he had calcium stones. We have since tried Hills Science Diet formulas cd, kd, cd/s. Over the weekend he was found to have another cluster of stones- we are now trying s/d. He is taking Methionine pills every single day and has been on and off of antiobiotics for the blood in his urine. I was wondering if we are going about this wrong for the kind of stones he has?? Any suggestions would be appreciated!!

If he has calcium stones again then the s/d won't help -- it is made for struvite stones. C/D, C/D-s is also made for struvite stones. C/D-o and U/D are the current Hill's diets for calcium oxalate stones. Eukanuba and Purina also have diets specifically for preventing calcium oxalate stones. It is very rare for cats to have a urinary tract infection so unless an infection has been documented via a urinalysis or urine culture/ sensitivity then I wouldn't use the antibiotics. The blood in the urine is most likely from the irritation secondary to the presence of the stones. Unfortunately, once calcium oxalate stones have been formed the only way to get rid of them is thru surgery. Diet can help prevent the formation of the stones but cannot remove calcium stones once they have formed. Citrate supplementation can also help prevent the formation of the calcium stones.

Struvite stones, on the other hand, can be dissolved with diet --Hill's S/D being the diet of choice and C/D or C/D-s being the preventative diet. Unlike in dogs, struvite stones are not associated with infection so again I would want conformation of an infection before using antibiotics.

Your veterinarian can have some idea as to the stones composition based on their appearance on X-ray, but the only way to know for sure what type of stone is present is to remove them and send them for analysis.

My suggestion at this point would be to consut with your veterinarian about which stone is likely to be present. If calcium oxalate was present before and you have been feeding c/d or c/d-s then most likely it is calcium oxalate that is present now. If that is the case, then surgery is the only option to remove the stones. I would definitely stop any anitbiotic therapy unless an infection has been documented. The s/d diet will slowly dissolve struvite stones but will make calcium oxalate stones worse. So, unless you and your veterinarian are very sure that the stones are composed of struvite I would not feed the s/d.

Hello, I am hoping you can help me as I am not in the financial position at the moment to take my cat to the vet. I have done a bit of research online and have come to the conclusion that my 3.5 year old male neutered cat has struvite stones. He has been straining to urinate for a couple of days and passes frequent small amounts. Last night he seemed to have emptied his bladder and was feeling like 'himself' again. This morning he is back to straining. I am hoping that it is a mild case and that I could attempt to treat him by changing his diet. He currently free feeds a dry cat food and has fresh water available at all times. Is there supermarket brand of wet cat food that you could recommend? I have read that feeding wet food with water added is a good treatment, proving extra hydration and a low PH level food. Would I be able to walk into a vets office and purchase a Hill Science Diet food with veterinary prescription? Also, my cat is a little overweight, so I assume this has contributed to the problem.

Shirley LeBlanc in Sussex, NB, Canada

Unfortunately, a cat straining to urinate is not necessarily indicative of struvite stones or any stones for that matter. Cats, particularly castrated males, develop a condition called Feline Lower Urinary Tract Disease (FLUTD) also called Feline Urologic Syndrome (FUS). In this condition mucus and protein form a sort of plug in the urinary tract causing straining and difficulty urinating. On the other hand, stones, both struvite and calcium oxalate, cause similar symptoms. You can try putting your cat on a diet for struvite stones BUT that will make the problem worse if the stones are calcium oxalate and won't do anything if the problem is FLUTD. There are several "urinary tract health" diets commercially availabe but the same holds true for them -- they will make calcium oxalate stones worse. Most vets will not sale Prescription Diets without seeing the animal first. I appreciate your situation but I am afraid that I don't have an easy solution for you because there are several causes of the symptoms that you are describing.

I have researched and answered these questions to the best of my ability. But I am human and make mistakes. If there is any part of my answer that you feel is incorrect, please let me know. The last thing I want is to disseminate false or incorrect information.