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Case Study: Renomegaly in a Young Cat

This week’s blog post is another case study for those new and in-training DVMs.

Case: 5-year-old male neutered DSH with history of lethargy and vomiting

My patient is a young outdoor barn cat with a history of lethargy and vomiting and not able to keep food down. He was seen by his regular veterinarian for deworming and vaccines approximately two months prior to coming to our ER service. The owner has noticed a significant amount of weight loss since his previous vet visit.

On physical examination he was normothermic, mildly depressed and mildly dehydrated. He had a bradycardia of 120 beats per minute and on palpation of his abdomen, he had larger than expected kidneys.

Once you have your exam findings, you come up with a list of differential diagnoses of those problems.

Vomiting: This clinical sign is non-specific for a cat, and could be anything from parasites (less serious) to cancer or severe kidney disease. A foreign object obstruction is also possible, or viral diseases like FeLV or FIP.

More concerning findings are: bradycardia and renomegaly.

The differential diagnoses for bradycardia in a cat would include electrolyte imbalances. This could include hyperkalemia - think about your blocked cats - but this cat did not have a distended, turgid bladder. Severe kidney disease, but not chronic kidney disease, because the kidneys were larger than normal on palpation. This could be heart related, heart disease or heart block.

The enlarged kidneys could point to polycystic kidney disease, infiltrative disease, or renal pelvic distension from hydronephrosis.

My first step for diagnostics in this indoor/outdoor cat was blood work. I offered a FeLV snap test as well, since that was on my list of causes of renomegaly, vomiting and lethargy.

The chemistry panel came back with severe azotemia with a creatinine > 800 umol/L. While we were waiting for the snap test, I did a quick ultrasound of the kidneys. Reference values for kidneys on ultrasound for cats suggests that normal is between 4 - 4.5 cm in length.

My suspicion for renal lymphoma was increasing. Looking at these kidneys we know we can rule out polycystic kidney disease and hydronephrosis. The complete blood count came back with a mild neutrophilia and mild lymphopenia. Nothing too interesting.

Then this snap test was completed:

Feline Leukemia Virus

In March 2020, I wrote about a young cat with anemia, which I said, in this 3-year-old cat, feline leukemia was high on my list of differentials.

A positive test is not necessarily a death sentence. Some cats can live with the virus, but these should be in single cat households and kept strictly indoors, as well as having routine veterinary care to ensure they do not get any secondary infections.

Feline Leukemia Virus is called the friendly cat virus, because it is passed through social interactions, grooming, sharing of food and water bowls, sharing of litterboxes - essentially through saliva and feces. This is in contrast to the angry cat virus (Feline Immunodeficiency Virus) which is spread through bite wounds.

Prognosis for long term several depends on which organ system is affected. If the bone marrow is affected (as in the cat from 2020), the prognosis is grave for any long term survival. On average, an FeLV positive cat can live 2.4 years after diagnosis.

For our cat in this case, we could have started chemotherapy, and we may have gotten remission of the lymphoma, but the median survival time is about 200 days. Chemotherapy in pets is variable depending on the oncologist, but it could mean that the cat is on medication every 3 weeks, getting blood work done just as often to assess the response to medication and whether the bone marrow can handle addition immunosuppression medication. My personal take on it, I wouldn't put my own cat through rigorous medications and testing, but palliative medications would likely be my own response.

Luckily, FeLV can be prevented. There is a vaccine to protect high risks cats. These would be indoor/outdoor cats, barn cats, or multi-cat households/catteries. There is no benefit to vaccination if the cat has already come in contact with the virus.

For more information on the Feline Leukemia vaccination, discuss this with your veterinarian.

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