Urolithiasis: Urinary Stones

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Most bladder stones can be seen on plain x-rays.

This week, we had several discussions around the clinic about bladder stones in cats and dogs. I thought this might be a good topic, as these often take owners totally by surprise.

Urinary stones can form from many different inorganic compounds and can make trouble anywhere along the urinary tract. Common types include struvite (magnesium-ammonium-phosphate, sometimes still referred to as “triple phosphate”), calcium oxalate (“CaOx,” which come in monohydrate or dihydrate varieties), urate, and cystine. Struvite and CaOx constitute by far the majority of stones seen in cats and dogs. Each type develops based on fairly specific conditions, such as urine pH, the presence of bacteria (struvite in dogs), or a primary disease process (urate with liver disease). In addition, breed-specific mutations may permit large amounts of the precursor compounds that lead to stone formation; this is true of cystine (Newfies, Dachshunds, and English Bulldogs) and urate (Dalmatians). More

PU/PD Series: Acute and Chronic Renal Insufficiency

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The nephron, the functional unit of the kidney, can be damaged in many ways to cause renal insufficiency.

Along with all the other organs that can cause PU/PD (increased urination and drinking known as polyuria/polydipsia), the kidneys themselves are sometimes to blame. While renal disease is complex, it is important to understand some acute and chronic kidney problems that lead to PU/PD.

With acute or chronic insults to the kidneys, the ability of the kidneys to concentrate urine is lost; in most cases, the renal tubules that are responsible for drawing water back out of the urine, are damaged. The pet urinates out a higher percentage of water, thus diluting the urine and leading to possible dehydration. The pet drinks more water to counter this loss, and is officially PU/PD. More

PU/PD Series: Diabetes Mellitus

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Nearly all diabetic dogs and over 50% of diabetic cats rely on insulin given by their owners.

Diabetes mellitus is a fairly common cause of polyuria/polydipsia in cats and dogs. In nearly all diabetic dogs and over 50% of diabetic are dependent on insulin given by owners. In the other 30-50% of cats, the disease can be treated with diet, exercise, and oral medications. Either way, it remains a difficult disease to manage.

What causes it? Diabetes Mellitus (DM) results from a drop in the insulin levels in the body (or, in some cases, the body’s perception that insulin levels have dropped). Insulin is produced by the pancreas and, among other things, acts on the liver, muscles, and fat deposits to cause them to take glucose out of the blood and store it as glycogen or fat. If the ß cells in the pancreas stop making insulin – or receptors in tissues stop recognizing it – the glucose stays at high levels in the blood, can spill into the urine, and can create a multitude of health concerns that we associate with DM, including cataracts, glaucoma, urinary tract infections, weakness in hind legs, and life-threatening ketoacidosis. More

Marijuana Intoxication in our Pets

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Medical marijuana edibles are attractive to some pets

Although it’s not very common to see dogs suffering from marijuana intoxication, we dealt with two such cases in one day last week. I took that as a sign that it was time to discuss the topic.

In one case, a 6-pound dog had ingested two chocolate chip and pot cookies 10 hours before calling us. The other case was a 50-pound pointer that had eaten one pot cookie the night before we saw him. The owners of both pets were forthcoming with information about what their pets ingested, which was very helpful.

Clinical Signs: The active ingredient in marijuana, tetrahydrocannabinol (usually called THC), can cause loss of coordination, restlessness or sedation, dilated pupils, and slowed heart rate and breathing. Occasionally, the pet may lose bladder control. Clinical signs usually begin 30-90 minutes after ingestion. More

PU/PD: What It is and What Causes It

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Owners notice when they need to fill the water bowl more than usual

If you look at the daily schedule in a vet’s treatment room, you might see something like this next to the patient name: “K9: √ ears” (check for infection/irritation in this dog’s ears), “lag: ADR” (the owner of this bunny thinks it “ain’t doin’ right”), or “fel: Ⓥ” (this cat has been vomiting). These are all very useful shorthand notations that allow the vet to start thinking about how to approach the case before she enters the exam room.

Another very useful abbreviation is “PU/PD.” This is shorthand for a medical term: polyuria and polydipsia, which simply means urinating and drinking more than normal. There are many possible causes of PU/PD in cats and dogs; so it’s important to make a mental rule-out list that’s consistent with species, age, and other owner complaints, like vomiting or weight loss. The important thing here is to start with the “horses” (as in, “when you hear hoof beats, think horses [common diseases], not zebras [rare diseases]”). So, what are the PU/PD “horses” for cats and dogs and how do you diagnose them? More

Otitis in Dogs and Cats: The Ears Have It

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A good ear exam is necessary for diagnosing otitis in dogs and cats

Ask your average small animal vet what problem area they see the most, and you’ll probably hear, “Ears.” And, while dogs are most commonly treated for problem ears, similar problems affect cats, too. What is it about ears that make them so prone to disease and what can owners and their vets do about it?

First, it’s important to have some vocabulary so we can be precise about ear problems. The ear flap (which actually stands up on cats and some dogs) is called the “pinna.” The tube that leads from the pinna toward the eardrum is the “canal.” The eardrum is sometimes called a “tympanum” or “tympanic membrane.” Normal discharge from the ear is “cerumen.” An infection or inflammation on the pinna side of the tympanum is “otitis externa.” If it affects the little bones and nerves just on the other side of the tympanum, it’s “otitis media.” And, rarely, we see the infection move further toward the brain into the region responsible for balance; this is “otitis interna.” By far, otitis externa is the most frequently seen type of ear problem in the cat and dog. More

Watch Out for Moldy Walnuts!


Beware: moldy walnuts are toxic to dogs!

A colleague of mine recently noted that, “It’s moldy walnut season again.” So, I thought moldy walnut toxicity would be a great topic for a post: Why are these walnuts moldy and how does that affect you?

The walnuts of concern are those that fall from trees and remain on the ground during and after wet weather. As they sit there through the cool, wet winter season, a mold forms on them; and although they can turn a furry black color, they often appear completely normal. Once the mold has formed, they are very toxic to dogs, horses, and virtually any other mammal willing to chew on them. More

Adventures with Canine Osteosarcoma, Part II


Since my recent post about Brick’s Osteosarcoma diagnosis and treatment plan, we’ve met with some obstacles. Last Monday, a scheduled chest x-ray showed a single pulmonary nodule (lung metastasis). Because Osteosarcoma spreads most commonly to the lungs, we were disappointed but not entirely surprised by the findings. In light of the nodule, Brick’s oncologists proposed we trade out the original doxorubicin/carboplatin treatment plan for something more tailored to the current situation.

The new plan involves aerosolizing and inhaling a chemo drug called Gemcitabine and infusing a drug called ifosfamide. Gemcitabine is given in human medicine as an IV infusion for lung cancer. But inhaled Gemcitabine is currently being studied by the oncologists at UC Davis Veterinary Medical Teaching Hospital as a new means of stopping the growth of existing lung tumors. The goal of aerosolizing the drug is to provide direct access to any tumors that lie along major airways; in addition, the drug absorbs into the pulmonary tissue and reaches the tumors that are in the vicinity of those tissues. Once in contact with the tumor, it interferes with the tumor’s ability to synthesize DNA, thus arresting growth. In the UC Davis study, it is given twice a week using a nebulizer and mask.

Ifosfamide is a nitrogen mustard alkylating agent. In simpler terms, it’s a drug that’s related to mustard gas; and it interferes with the existing DNA in tumor cells, causing cell death. It’s used in human medicine for various sarcomas and Hodgkin’s disease. It is given every three weeks as an IV infusion over 6-8 hours with fluids.

For dogs with pulmonary metastases that do not pursue treatment, the median survival time (MST) is around 60 days. With treatment, we are hopeful we will have Brick closer to 8 months, which is the MST for this protocol. I will keep you posted.


[note: there is a follow up to this post, dated July 25, 2011]

What to Feed Your Pet, Part I: Cats and Dogs

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What to feed your pet can be a daunting decision.

The question I get asked the most is, “What should I be feeding my cat/dog/rabbit/other?” Most owners want to provide the best for their pets – and nutrition is no exception. But this is a very complex issue. Pet food marketing messages, misinformation about various pet food manufacturers, the costs of commercial diets, recall alerts, and a new focus on alternative therapies in human nutrition all lead to confusion about the choices.

For cats and dogs, the two primary choices are commercial diets (bags or cans from the store or vet clinic) and home-prepared diets. Pet owners may opt for one, the other, or a combination of both.

Within these broad categories are several distinctions that need to be addressed. 


In Our Cats and Dogs – Size Matters!

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Keep your pet healthy, not round!

People are often surprised when I point out that their dog is a little “round.” I’m not sure what they think “healthy” looks like in a pet – but it looks surprisingly similar to markers of good health in people: lean body with good muscle tone. Yet people often fail to notice when one of these health indicators slips in their beloved pets.

Leanness = Health. Many studies, including a pioneering canine life span study by Purina, show that dogs that have controlled food intake and are maintained at lean body condition outlive their overweight siblings by an average of 20 months, with a similar delay in the onset of serious disease. Studies in mice support these findings, as well.


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