2016 WINTER: Frostbite 2016 | Save a Tooth | E-cigarettes | Osurnia | ACVIM Pearls | Canine Laryngeal Mass | Technology Limits | Clinical Trials
How to Save a Tooth
In the not too distant past, extraction was the only treatment available in dogs and cats for infected, painful or dead teeth. To remove a tooth by extraction, the bone surrounding its roots must be removed. Mucoperiosteal flaps must then be created and transposed to cover the hole left by the removed tooth. This causes discomfort for the patient and results in complete loss of what was previously a functional tooth.
There is a better option. In many patients root canal therapy can be used to save the tooth and resolve the infection. A small access hole is drilled through the crown of the tooth into the pulp chamber. Through this hole the root canal is enlarged and sterilized. An inert material is then injected into the root canal filling any space inside the tooth where bacteria and toxic substances can accumulate.
The access hole is then filled with an appropriate restorative material resealing the surface of the tooth and making it functional and pain free. Additional preparation of the crown of the tooth receiving root canal therapy may further protect the restoration site and function of the tooth. A cast metal crown is often recommended for dogs with chewing behavior problems and working and hunting dogs.
Not all teeth require a root canal procedure. This procedure is typically recommended for those teeth that have important grabbing and chewing functions. These include the canine teeth and the large premolars and molars. Extraction of canine teeth requires the removal of large amounts of surrounding bone, which can weaken the jaw or create a hole from the mouth into the nasal passage. Premolars and molars are large multi-rooted teeth whose roots extend deep into the bone of the jaw. They are also very difficult to remove. Saving these teeth avoids a painful surgical extraction and maintains chewing function.
Why do teeth die?
Within each tooth lie the nerves, blood vessels and other tissues that support and nourish the tooth. This region of the tooth is called the root or pulp canal.
Exposure of the pulp canal from a tooth fracture can lead to its invasion by bacteria. The subsequent infection will extend down the tooth eventually invading the root tip and the surrounding bone of the jaw. Initially, pain and discomfort will be noted. Ultimately, the affected tooth may fall out. Blunt trauma from chewing hard objects can also damage the blood vessels within the tooth. Loss of blood flow to the tooth will cause it to die. Discoloration of the tooth and a predisposition to infection can develop.
The Dangers of E-cigarettes
With the increased popularity of the e-cigarette, as an alternative to the more popular and conventional cigarette, has also come an increase in the number of hospital admissions to many veterinary emergency clinics. E-cigarette ingestion/exposure poses a serious risk to pets, but unfortunately outside of the veterinary world, this information may be relatively new or unheard of to many pet owners. The primary concern with the ingestion of e-cigarettes has to do with the ingestion of its ingredient, nicotine. While the e-cigarette may seem relatively harmless, each cartridge packs a powerful punch, containing anywhere from 6 to 24 mg of nicotine; in contrast the average cigarette only contains approximately 9 mg of nicotine. Although the e-cigarette resembles the traditional cigarette, e-cigarettes work by atomizing liquid (containing nicotine) into a vapor that can be inhaled. Many people who use these products also enjoy the different flavors and varieties that these products come in, ranging from peppermint to cherry. The aroma or scent of these e-cigarette cartridges is what makes them a popular target among pets. Pets are drawn to these different scents and in many reported cases ingest the flavored nicotine liquid.
In addition to the increased nicotine content of these products, vials of liquid nicotine, called “e-juice,” are often available to refill cartridges. Moreover, pre-filled cartridges are often sold in packs containing up to 20 or more individual cartridges. This added danger makes intoxication almost guaranteed, whereby pets are likely to show severe clinical signs up to and even including death. According to Pet Poison Helpline, a 50-lb dog ingesting a single cartridge will often show clinical signs; whereas consumption of the same quantity by a 10-lb dog will often result in death. On the other hand, signs may vary with partial consumption. In addition, consumption of e-cigarettes, and or any of their parts may result in severe gastroenteritis or gastrointestinal obstruction.
The onset of clinical signs is rapid, with pets showing signs such as vomiting, diarrhea, tachycardia, tachypnea, neurologic signs like tremors, ataxia, weakness and seizures, in as little as 15 minutes. Cardiac arrest and even death is observed as well. Delayed signs has been documented especially with cutaneous exposures. Below is a listing of clinical signs by the system affected:
- Gastrointestinal: vomiting, hypersalivation, diarrhea, abdominal pain/discomfort
- Cardiovascular: hypertension, cardiac arrhythmias
- Neurologic: ataxia, weakness, mydriasis, seizures
- Pulmonary: initial tachypnea followed by respiratory depression
The diagnosis is often made possible by a history inclusive of exposure to nicotine and is often suggested by the combination of clinical signs with their acute onset. Differential diagnoses should include other potential toxicants with similar clinical signs. Metaldehyde, bromethalin and methylxanthine products; insecticides (carbamates, organophosphates), strychnine, mycotoxins, and toxic mushrooms are among the most common. Bloodwork is often non-specific, with some pets showing hyperkalemia. More advanced laboratory analysis of blood and vomitus, such as HPLC, or mass spectrometry is possible, although often not feasible given the time it takes to send off these samples to a reference laboratory.
Although there is no specific antagonist treatment for nicotine intoxication, treatment is aimed at controlling signs of respiratory distress, cardiac arrhythmias, cardiovascular collapse, shock and general supportive care with intravenous fluids, gastroprotectants, anti-emetics and oxygen therapy. Cutaneous or ocular exposure should include decontamination of the affected surface with copious amounts of a lavage solution (ocular), or bathing with soap and water (cutaneous).
If a known ingestion occurs, immediate veterinary care is recommended. At-home care is not recommended due to the rapid onset of clinical signs and severity of symptoms. It is recommended that owners take their pets to the closest emergency clinic and or contact either, Pet Poison Helpline (800.213.6680) or the ASPCA Animal Poison Control Center (888.426.4435) for further advice.
Osurnia: A New Product for a Challenging Problem
Many of us cringe when our clients present their dog for ear problems. The discomfort associated with ear conditions can make infected and inflamed ears both difficult to examine and to clean. Our owners face the same challenge when we ask them to clean and medicate their pet’s ears at home, so it’s no wonder many ear conditions don’t resolve and eventually become chronic problems. Because of their pet’s extreme discomfort, owner compliance with our treatment recommendations may not be realistic. And who can blame owners for their failure? Ears are hard to treat.
There may be a solution. Elanco Animal Health has developed a product, Osurnia®, to help us treat what some owners consider untreatable. Osurnia gel comes in a single-use tube. The product contains florfenicol (which is similar to chloramphenicol) to treat bacteria, terbinafine to treat yeast, and betamethasone to reduce inflammation. Its advantage is its two-dose treatment regimen. The medication is squeezed into the ear canal and massaged to spread the formulation. This is repeated 7 days later. That’s it. The infrequent dosing is a tremendous advantage when it comes to owner compliance. The ear should not be cleaned between uses or prior to the second administration to ensure the medication remains in contact with the ear canal surface.
According to the product label, Osurnia has not yet been evaluated in dogs with perforated ear drums, and therefore should be avoided in these patients. Vomiting was an infrequent adverse effect noted during clinical trials as was an elevation in the ALP value (probably secondary to the corticosteroid). Osurnia is not approved for use in cats.
Osurnia would be expected to be very effective for curing simple otitis. The recurrence of ear disease would suggest the need to identify and address an underlying cause. Should you have a pet with recurrent and/or poorly responsive disease, further evaluation by a dermatologist is suggested.
From the 2015 ACVIM Forum
Can you trust the urine SG (USG) in dogs with glucosuria?
A recent study evaluated the effect of adding increasing concentrations of glucose to urine samples with varying starting USGs. Predictably they found that the lower the starting nonglucosuric USG, the greater the effect adding glucose had on the subsequent USG. Furthermore, the higher the concentration of glucose added to the urine sample, the greater the change in the subsequent USG. However, the addition of even higher concentrations of glucose to urine samples with low USG failed to cause clinically significant changes in the final USG. Researchers concluded that the presence of glucosuria did not interfere with the assessment of renal concentrating ability. (Behrend et al)
Are all antiemetic medications the same?
Well that depends on your goal. Gastric antral motility (contractions per minute) was measured before, during and hourly after the feeding of a meal in normal dogs given metoclopramide, maropitant, dolasetron or saline 1 hour prior to feeding. Researchers found that all three medications increased gastric motility prior to feeding and then intermittently during hourly measurements performed for 7 hours after feeding. Only metoclopramide increased motility at all time measurements. If the goal is only to inhibit nausea then all three medications can be effective. However, if increasing gastric emptying is also the goal, then metoclopramide may be your drug of choice. (Bogard et al)
So how do the new anti-seizure medications add up?
Phenobarbital still appears to be one of the most effective medications for treating seizures in dogs. Alternative medications continue to be evaluated with the goal of avoiding the short-term side effect of sedation and long-term side effect of potential liver disease. A review of records of dogs receiving zonisamide (40), levetiracetum (16) or phenobarbital (65) as first line therapy for control of seizures found that phenobarbital was more likely to be associated with adverse effects but was also most effective as monotherapy to control seizures. Dogs receiving zonisamide or levetiracetum were ultimately more likely to require additional therapy to reduce seizure frequency. (Waldron et al) In another study evaluating zonisamide alone, approximately 75% of 53 dogs demonstrated a 50% reduction in seizure frequency. (Nomura et al)
From the 2015 ACVIM SAIM Endocrine Course (a 20-hour advanced endocrinology course)
Diabetic remission in cats – what can we realistically expect?
Some studies have cited a remission rate in diabetic cats of up to 100% using twice-daily glargine insulin and an ultra-low carbohydrate diet, but most have not been able to replicate these results in practice. A recent review evaluated the available literature regarding diabetic remission in cats (Gostelow, R et al. Systematic review of feline diabetic remission: separating fact from opinion. The Veterinary Journal 2014; 208-221); a more realistic remission rate to expect in practice is 30-50%. Most cats achieving remission will do so in the first 6 months following diagnosis. Factors associated with a higher rate of remission include older age at diagnosis, lower blood glucose at diagnosis, lower mean 12-hour blood glucose concentration, good glycemic control within 6 months, treatment with steroids in the 6 months prior to diagnosis, and a lack of neuropathy.
Diagnosing hyperadrenocorticism in dogs – do we need to rethink the available screening tests?
Hyperadrenocorticism (HAC), or canine Cushing’s syndrome, is a commonly encountered endocrinopathy that can be difficult to diagnose. The ACTH stimulation test and low-dose dexamethasone suppression test are useful in screening for HAC, but there is now concern that a diagnosis may be missed in some affected patients because the reference ranges are too broad (Behrend, EN et al. Diagnosis of Spontaneous Canine Hyperadrenocorticism: 2012 ACVIM Consensus Statement. J Vet Intern Med 2013;27:1292–1304). Specifically, the upper end of the ranges for the post-ACTH stimulation cortisol and the post-low dose dexamethasone suppression 4- and 8-hour cortisol samples may be too high. While reference ranges must be established for each individual assay in each lab, the diagnostic labs at both UC Davis and Cornell have lowered their normal ranges for these tests. Additionally, keep in mind that an asymptomatic, isolated elevation in alkaline phosphatase on a biochemistry profile is a non-specific finding and alone does not warrant a work-up for HAC.
Diet-induced hyperthyroidism – gee whiz!
A recent case series described hyperthyroidism in 12 dogs being fed raw meat diets that were either known to contain fresh/dried gullet tissue or suspected to be contaminated with thyroid tissue (Köhler, B. et al. Dietary hyperthyroidism in dogs. Journal of Small Animal Practice (2012) 53, 182–184). Six dogs showed clinical signs including weight loss, aggression, tachycardia, panting and restlessness, while the other six dogs had no clinical signs. Follow-up was available for eight dogs; clinical signs and bloodwork abnormalities, when present, resolved in all affected dogs after being changed to a commercial diet. While hyperthyroidism in dogs is almost always associated with a functional thyroid tumor, it is important to obtain a thorough dietary history from the client.
Canine Laryngeal Mass? Consider a Thyroid Tumor
The presence of a firm mass in the ventral cervical neck region overlying the larynx of dogs should make you suspicious for a thyroid tumor. Few other tumor types develop in this location. The mass is most commonly an incidental finding by the pet owner or noted on physical exam. Less frequently, owners will note a laryngeal stridor. Unlike cats with thyroid tumors, clinical signs of hyperthyroidism are uncommon. Most thyroid tumors in dogs are nonfunctional, but also more aggressive. Up to 40% of dogs with thyroid tumors may demonstrate evidence of metastasis on thoracic radiographs at time of diagnosis. Approximately 80% of canine thyroid tumors will eventually metastasize.
Ultrasound or CT scanning of the neck region is performed to assess the tumor’s invasiveness. In our experience, thyroid aspiration cytology, which can be quite bloody, will provide a definitive diagnosis in the majority of patients. The absence of other cell types can effectively exclude other possible causes for the mass.
Surgery is the best treatment option for thyroid tumors. Survival times of up to 3 years can be achieved when the mass is freely moveable and 6 to 12 months if it has invaded into the surrounding tissues. The proximity of these tumors to major blood vessels and nerves in the cervical neck region can make surgical resection challenging.
Radiation therapy has also proven effective for treating thyroid tumors and is a good adjunctive choice for tumors that cannot be completely resected. Radiation therapy slowly kills cancer cells so it can take 8 to 22 months for the mass to decrease in size. This is not a quick enough option for dogs if the mass is obstructing breathing.
Radioactive iodine has also been used to treat some dogs with thyroid tumors. It can be effective against metastatic or residual thyroid neoplasia with survival times of 2 years being reported. However, unlike cats with hyperthyroidism, most dogs do not trap the iodine in their thyroid tumors, which is required for the treatment to be effective. Technetium scanning is performed to determine whether radioactive iodine treatment could be effective. Dogs require much higher doses of radioactive iodine than cats, and therefore are quarantined longer.
Should you suspect the presence of a thyroid tumor, give oncologist Dr. Heather Heeb a call. Various imaging, surgery and chemotherapy options are available at our BluePearl Northland, Lee’s Summit and Overland Park hospitals. Radiation therapy is available in Overland Park.
FROM THE MEDICAL DIRECTOR
Frostbite Is Coming
The signs of winter will soon be upon us and that can mean only one thing, Frostbite is coming. Our tenth annual Frostbite Continuing Education Symposium is scheduled for Sunday, February 21, 2016 at the Overland Park Convention Center. Last year over 400 veterinarians were, dare we say, entertained by 20 speakers from the Kansas City area on topics ranging from practice finance to nasal discharge.
The thirty minute talks will begin at 8:00 am and run to 3:00 pm. Once again, we will be offering the event free of charge thanks to our many Partners in Education.
So reserve the date. Don’t miss out on the chance to socialize with old friends, grab a free lunch, and pocket some CE credits. We will be sending more information shortly.
Technology’s Limitation – Us
The price of technology is becoming more affordable, which is a good thing for all of us. We can now afford to provide advanced diagnostics that previously were beyond the financial means of our clients. Our patients and clients benefit from more accurate and more rapid diagnoses.
But the challenge to all of us using new technology is getting experience with its use. It’s what we don’t recognize or see, because it’s all so new, that we have to worry about. Only experience can teach us what is normal or abnormal on an ultrasound evaluation, endoscopic view or CT image. And that knowledge can take years to develop. How can we be expected to recognize what is causing the lesion if this is the first or second time we have seen it?
And so, as we all reach for new technology, we have to be honest with ourselves and our clients. We should be limiting ourselves to diagnosing the things we recognize and still reaching out for the opinion of those with more experience to let us know what we are missing. With time and experience we will be able to recognize more and more for ourselves.
Jeff Dennis, DVM, DACVIM
Clinical Trials in Kansas City
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