The Dangers of Antifreeze and Your Pet

Written by: Tabitha Schmidt, Client Care Supervisor

 

Antifreeze poisoning is one of the most commons forms of poisoning in small animals because it is a common household item. Antifreeze poisoning typically happens when the substance is leaking from a car’s radiator and your pet can potentially lick it off the ground and ingest it. It is also used in some toilets at home to make sure pipes do not freeze during the winter months.

 

What makes antifreeze lethal?

The toxin in antifreeze that makes the liquid lethal is called ethylene glycol. Dogs often consume large quantities before being repulsed by the aftertaste. It does not take much for the effects to cause fatal damage to your pet affecting the brain, liver and kidneys.

 

Symptoms of antifreeze poisoning:

Common symptoms include:
  • drunken behavior
  • euphoria/delirium
  • wobbly, uncoordinated movement
  • nausea/vomiting
  • excessive urination
  • diarrhea
  • rapid heart beat
  • depression
  • weakness
  • seizures/convulsions/shaking tremors
  • fainting
  • coma

Diagnosis

Primary care veterinarians diagnose your pet with antifreeze ingestion by conducting a complete blood profile. This includes a chemical blood profile and a urinalysis. A vomit and stool sample will also help diagnose the type of poison and to expedite your dog or cat’s treatment.

 

What to do if your pet ingests antifreeze

If you think your pet may have ingested antifreeze, seek immediate veterinary attention.
Pets that have consumed antifreeze in a small quantity may survive but can develop kidney failure within days of ingestion. Unfortunately, death is very common due to kidney failure.

 

How to prevent antifreeze poisoning

Prevention to keep your pets safe from the harmful toxins of antifreeze include:
  • Keep containers tightly closed and out of reach of pets.
  • Take care not to spill antifreeze – if spilled, ensure that it is cleaned up immediately and thoroughly.
  • Dispose of antifreeze containers properly.
  • Check the radiator of your car regularly and have any leaks fixed in a timely manner.
  • Do not let your pet wander unattended where there is access to antifreeze.
  • The U.S. Food and Drug Administration has labeled propylene glycol safe and it is now used for antifreeze. Look for antifreeze with this ingredient instead, to keep your pet safer from accidental poisoning.

The Dangers of Essential Oils and Pets

Written by: Tabitha Schmidt, Client Care Supervisor

 

With essential oils becoming more popular in health, natural cleaning products, and relaxation it is good to know how this affects your furry house mates. Essential oils are the extracted organic components of plants that give them their characteristic fragrance or taste. They are popularly used for aromatherapy by inhalation (candles, incense, diffusers) or rubbing into the skin (perfumes and oils). They are also found in many insecticides, personal care products (e.g., antibacterials), flavorings, herbal remedies, and liquid potpourri.

Unfortunately, there are a lot of essential oils that are harmful to your cats and dogs, whether it be by diffusing machine or the oil itself. Our pets have a stronger reaction to these products than we do. Many essential oils are toxic to pets and may cause severe respiratory irritation, GI upset, liver failure, paralysis, and other life-threatening symptoms listed below.

Essential Oils Which are Poisonous to Dogs

According to the Pet Poison Helpline

  • Tea tree oil (Melaleuca oil)
  • European Pennyroyal/squaw mint
  • Oil of Wintergreen
  • Pine Oils

Essential Oils Which are Poisonous to Cats

According to the Pet Poison Helpline

  • Oil of Wintergreen
  • Oil of Sweet Birch
  • Citrus oil (d-limonene)
  • Pine oils
  • Ylang Ylang oil
  • Peppermint oil
  • Cinnamon oil
  • Pennyroyal oil
  • Clove oil
  • Eucalyptus oil
  • Tea tree oil

Symptoms to Watch Out For

A few red flags that we should be looking for are:

  • Behavior changes (depression, fatigue, weakness)
  • Difficulty breathing (labored breathing, fast breathing, coughing, wheezing)
  • Drooling and/or vomiting
  • Tremors
  • Ataxia (difficulty walking, stumbling, wobbling)
  • Redness or burns around the mouth or nose
  • Paralysis of the rear legs

Precautions to Take

Prevention is key. The precautions you can use are pretty simple. Keep these essential oils out of reach of children and your pets in a secure container and ask your primary veterinarian what you can use and what could be harmful to your pet. There are also alternative products that you can use that are calming and not harmful for you pet in a stressful situation that are available in treats, capsules, or liquids.

If you think your pet may have been exposed to an essential oil, please don’t hesitate to give us a call or bring your pet to the nearest emergency veterinarian. You may also consider calling the 24/7 Pet Poison Hotline with questions or for advice.

Pet Car Safety and Canine Seat Belts

Written by: Lucas Daly, Veterinary Technician

 

Most of us drive with our pets regularly, whether it is to the dog park, a vet appointment, or just running some errands around town. In most states it is required by law that people use vehicle safety devices (aka seat belts) to reduce the risk of serious bodily harm in the event of a collision or vehicular accident. The CDC states that “seat belts reduce serious crash-related injuries and deaths by about half.” This is great news and practice for us while on the road, but what about our canine companions that travel with us in the car?

With winter upon us here in New England, there is an increased risk of accidents and collisions due to winter travel conditions. While there are no seat belt laws for dogs, there is an increasing awareness and use of canine safety belt harnesses and restraints while traveling in the car.

What is a Canine Seat Belt?

Dog seat belts are more commonly known as dog car harnesses, which attach a full-body harness to the seat belt system in the back seat of the car. Dogs are safely and easily clipped in with a short leash. Most are customizable to the dog’s size and comfort.

Benefits of Dog Car Harnesses

Safety

First and foremost, dog car harnesses keep your dog safe. In the event of an accident, the harness and leash would minimize force on the dog’s neck, significantly reducing the risk of injury to both the dog and the driver. They also prevent dogs from falling or jumping out of the window which can cause serious injuries.

Most safety harness are crash-tested and DOT-approved, so your dog can have the same safety and security as you do with your seat belt.

A source of comfort for your dog

By securing your dog to one place with a dog car harness, your dog may feel less anxious and more secure while driving with you. It may also help with car sickness since they won’t be rocking and shifting around so much.

Minimize distracted driving

Many dogs tend to move around, fall over, or try to climb into the front seat with you while driving. This can be dangerous for the driver if it takes their eyes off the road or their hands off the wheel. By having your dog strapped in with a harness, the driver can focus on the road and not the antsy dog in the back seat.

Other Car Safety Options for Your Dog

  • Crate: A travel specific crate designed to be sturdy and padded, and sometimes strapped to the floor of the trunk of rear seat for added stability.
  • Back Seat Barrier: This barrier blocks the space between the front and back seats which prevents dogs from climbing into the front seat or tumbling forward in a crash.
  • Leash & Zip Line: Attaching to the car’s cargo hooks, this will provide security while allowing your dog to move around in the back seat.
  • Pet Car Seat: For smaller dogs or cats, a car seat designed especially for pets can keep your pet in place while still allowing them to see all the wonders racing by out the window.

The American Kennel Club has some suggestions on what to look for in both Safety Harnesses and Travel Crates. Additionally, the Center for Pet Safety has published crash test results and recommendations on safety harnesses.

Whichever method you choose, we fully support increasing safety for our clients and patients, and encourage anyone who travels by car with their pets to consider safety options for the coming winter months and beyond.

We wish you many more wonderful and safe adventures with your pets!

Electrochemotherapy

Written By:  Courtney Zwahlen, DVM, DACVIM (Oncology)

Electrochemotherapy (ECT) is a local treatment for cancer using a combination of chemotherapy and electric pulse therapy which increases the antitumor effect of the chemotherapy drugs.

The procedure uses short high voltage pulses generated via an electric pulse generator machine. Once the pulses have been delivered, the cell’s plasma membrane has increased permeability to the chemotherapy agent which is administered either intratumorally or intravenously.

The two chemotherapeutics that have shown the most promise and are used most commonly are bleomycin and cisplatin.

  • Bleomycin, an antitumor antibiotic, is a hydrophilic drug that has very limited transport through the cell membrane but is extremely cytotoxic once bound to DNA. Bleomycin efficacy appears to be potentiated 1000 fold with electroporation of cells.
  • Cisplatin, a platinum containing chemotherapeutic, also has difficulty getting through the cell membrane but is quite cytotoxic once bound to DNA. Electroporation of cells showed increased cisplatin cytotoxicity up to 80 fold.

Mechanisms of Action

Various mechanisms of action of ECT have been described.  Electropermeabilization of the tumor cells leading to increased intracellular drug accumulation, vascular effects, and an increased immune response appear to be the most important.

The principal mechanism of action is increased cellular uptake of bleomycin or cisplatin by exposure of the tumor cells to an electric field (Fig. 1).

The vascular effects include two distinct changes, vascular disruption and vasoconstriction. The vascular disruption involves endothelial cell death and consequently a decrease in local blood flow. The vasoconstriction effect, also known as vascular lock, induces prolonged entrapment of the chemotherapy drug within the tumors.

The last mechanism of action involves antigen shedding by the tumor cells that are destroyed by ECT which can induce some systemic immunity.

Based on the various mechanisms of action of ECT, antitumor activity should be observed in many different types of tumors treated, regardless of their histological type.

An electric pulse applied at the time of maximal drug concentration in the tumor optimizes the antitumor effect. The best timing of the electric pulses for intratumoral administration is immediately after drug injection, whereas for intravenous administration it is 4-8 minutes after drug injection. The drugs remain at a sufficient concentration in the tumor for at least 20 minutes.  At longer intervals between electric pulses and chemotherapy administration, the antitumor effectiveness of ECT is decreased. Intratumoral delivery of chemotherapy generates higher drug concentrations locally in the tumor, and lower concentrations in the non-target tissues when compared to intravenous administration. The drug doses are so low whether administered intratumorally or intravenously that they have minimal to no systemic side effects.

Fig. 1
a. Anticancer drug surrounding the cell
b. Electroporation exposes a cell to a high-intensity electric field that temporarily destabilizes the membrane. During this time the membrane is permeable to the anticancer drug surrounding the cell.
c. When the field is turned off, the pores in the membrane reseal, enclosing drugs inside.
Source: Leroy Biotech 

Procedure

The treatment procedure consists of anesthetizing the patient, injecting the chemotherapy either intratumorally and/or intravenously, waiting the appropriate amount of time and then applying the electric pulse (Fig. 2).

In order to get good contact between the electrodes and skin, KY or ultrasound gel is used.  Only minor immediate side effects have been noted in people and animals treated with ECT. The most common side effect reported is involuntary contractions/spasms of the underlying muscle in the treated area, but the spasms are only present during the application of the electric pulses. Any associated pain dissipates immediately after the electric pulses are discontinued.  Another immediate side effect that has been observed is minor irritation locally.

More delayed side effects can occur and include erythema, edema, and possible necrosis of the tumor. In most cases, patients typically only need one to three treatments, and each treatment under general anesthesia typically takes about 20 minutes. In some cases, tumors may need more than one treatment, especially if the tumors are large.

Fig. 2
a. General anesthesia to ensure security of patient and practitioner.
b. Drug injection: Intratumoral or intravenous injection of cisplatin or bleomycin
c. Applying electric pulses: 8 pulses of 100 μs every 2 ms (ESOPE standard protocol 2006).
Source: Leroy Biotech 

Indications

Electrochemotherapy appears to be a promising and relatively inexpensive local treatment option for dogs and cats with a variety of tumors. It has been utilized for a variety of tumors including squamous cell carcinoma, soft tissue sarcomas, mast cell tumors, localized lymphomas, melanomas, transmissible venereal tumors, perianal adenomas, anal gland adenocarcinomas, sarcoids, and fibropapillomas (Fig. 3-5).

This technique can be used for incompletely excised tumors and/or tumors that cannot be excised without significant complication/deformity to the patient. It can be considered as an alternative to radiation therapy for those patients that are unable to undergo radiation therapy for various reasons.  I

The treatment can be performed on an outpatient basis, it is safe, and shows good long-lasting objective responses in approximately 80% of patients.

Patients often require 1-3 treatments given once every 2-4 weeks, depending on response.

Local side effects, such as tumor necrosis, are to be expected pending the amount of active tumor that is being treated.

Supportive care, such as bandage changes, anti-inflammatories and antibiotics, are utilized until the treated wound has healed.

Fig. 3
Incompletely excised soft tissue sarcoma over metacarpal region.
Images progress from escar formation, tumor necrosis, debridement and healed wound.
One year later, patient is comfortable with no scar or tumor recurrence.

Fig. 4 Epitheliotrophic Lymphoma affecting lower lip and gingiva.
a. Pre-treatment.
b. Immediately following treatment.
c. 9 days post treatment showing initial tumor necrosis.
d. 12 days post treatment with progressive tumor necrosis.
e. 21 days post treatment, healing mucosa.

Fig. 5 Feline nasal planum squamous cell carcinoma.
A. Before treatment
B. 2 weeks post
C. 4 weeks post
D. 8 weeks post. Complete response >1 year.
Source: Leroy Biotech 

Platelet-rich plasma (PRP): A newer biological approach to age-old treatment difficulties

Written by: Kristian Ash, BVMS, MRcVS, DACVS-SA

What is PRP?

Regenerative medicine is one of the newest fields of medicine and aims to prompt the body to heal itself by using the bodies own cells and substances to restore and repair damaged tissues. Although still in its infancy, regenerative medicine techniques are starting to permeate the veterinary field. When used in the orthopedic field, regenerative medical treatments (Stem cells, PRP, IRAP) are referred to as orthobiologics. The most widely used orthobiologic in small animal clinical practice is platelet-rich plasma.

Platelet-rich plasma (PRP) is an autogenous concentrate composed primarily of platelets and white blood cells. It is used as a biological supplement to facilitate delivery of vital growth factors required to stimulate healing. Although the utility of PRP is continually being expanded, its use in veterinary medicine is primarily associated with wounds and orthopedic applications.

A benefit of PRP is that it is not administered systemically, but rather applied directly to the site of tissue damage by intra-articular injection, peri-tendinous injection, or topical application.

Physiology/pharmacology

Platelets are among the first wave of cells that migrate to a site of injury following tissue trauma. Not only do they provide a critical hemostatic function, but they also release and provide growth factors required to stimulate the healing process. Platelet-derived growth factor (PDGF), transforming growth factor beta (TGF-β1 and TGF-β2), vascular endothelial growth factor (VEGF), basic fibroblastic growth factor, and epidermal growth factor (EGF) are all brought to the site of injury from the alpha granules of platelets.

Of particular importance, are the delivery of PDGF and TGF-β.  PDGF stimulates angiogenesis, mitogenesis, and activation of macrophages.  TGF-βaccelerates the production of collagen from fibroblasts.

PRP may also help to decrease inflammation by modulating interleukin-1 production.

Extraction

PRP is made by centrifugation of a whole blood sample. The resultant buffy coat and plasma are then extracted, and the leucocyte concentration further reduced.
The resultant concentrate has approximately 4-8 times the concentration of platelets than whole blood. During the preparation process, white blood cells are filtered out, as increased leukocyte concentrations have been linked to increased scar tissue formation, increased collagen degradation, and decreased tendon matrix production.

The platelet concentrate can then be used as a small volume liquid, or can be mixed with thrombin and calcium chloride to produce platelet-rich fibrin (PRF) gel.

Applications

Applications for PRP in small animal veterinary medicine are ever expanding. Currently, the most common applications appear to be in osteoarthritis (OA) management as well as tendon and ligament healing.

Intra-articular injections of PRP have been used in the treatment of osteoarthritis. Managing OA can be exceedingly frustrating due to the poor healing characteristics of articular cartilage. The avascular nature of articular cartilage severely limits the efficacy of systemic treatments. Local delivery of growth factors therefore is markedly advantageous to stimulate reparative processes on the joint surface. The evidence for PRP in osteoarthritis models in dogs is mounting. A randomized controlled clinical trial performed in 2013 showed subjective and kinetic improvement in gait 12 weeks following PRP injections for OA of a single joint. Likewise, a 2016 trial showed efficacy of multiple intra-articular injections of PRP following arthroscopic treatment for canine elbow dysplasia. Based on these studies, PRP injections following arthroscopic elbow surgery are one of the most common applications of PRP here at PEAK.

Another exciting area for the use of PRP is in aiding tendon and ligament repair. As with articular cartilage, the vascular supply to tendons and ligaments is typically poor and as such, limits their intrinsic healing capacity. Local administration of PRP to healing tendons and ligaments may help increase the likelihood of successful repair. A recent study in 2016 showed improved healing of the Achilles tendon when PRP was used as an adjunctive treatment to surgical repair. We now use PRP injections with all our Achilles tendon repairs and have found the results excellent.

Limitations

As with any therapeutic intervention, PRP does have its limitations and considerations. Its use in treating cranial cruciate disease, the most common ligament injury we face in small animal practice, is limited. A 2016 study compared dogs treated with PRP alone versus those treated with nothing. The results showed improved cartilage health, limb function, and range of motion using multiple PRP injections over a 6 month period, however the cranial cruciate ligament continued to degenerate and there was no difference in the radiographic appearance of OA regardless of whether or not PRP was administered.  In an unrelated 2016 study where PRP was used alone to treat partial tears of the cranial cruciate ligament following arthroscopy, the results were encouraging with 30% of patients showing some improvement in gait, yet only 25% of patients had documented improvement in the health of the cranial cruciate ligament. These results suggest that PRP can be an effective therapy following surgical stabilization of the stifle to help in decreasing the effects of ongoing osteoarthritis, but that it is ineffective in the management of partial or complete cruciate ligament ruptures.

The risks associated with PRP injections are very low as it is a product of the patient’s own blood. The biggest risk associated with PRP is septic arthritis, an extraordinarily rare consequence of any intra-articular injection.

Conclusion

Platelet-rich plasma injections are a low risk, promising new regenerative therapy that may aid in the treatment of challenging orthopedic conditions in small animal veterinary medicine. The clinical use of PRP is increasing as the level of evidence for its efficacy continues to expand.

Laryngeal Paralysis Review

,

Written by Kurt S. Schulz, DVM, DACVS

Laryngeal paralysis is one of the most common causes of respiratory dysfunction and distress in older large breed dogs.  It may present either as a chronic progressive increase in upper airway noise and exercise intolerance or as a respiratory emergency with severe inspiratory distress.  Fortunately, surgical treatment is highly successful with infrequent complications and a high degree of client satisfaction.

Causes and pathophysiology

The specific causes of acquired laryngeal paralysis remain uncertain but are associated with dysfunction of the laryngeal muscles and recurrent laryngeal or vagus nerves.  The primary muscle responsible for abduction of the arytenoid is the cricoarytenoideus dorsalis which is innervated by the recurrent laryngeal nerve. This neuromuscular mechanism may undergo idiopathic failure in older large breed dogs leading to inspiratory difficulty.  The clinical signs are exacerbated by heat and exercise due to the effects of increased respiratory effort on the rima glottidis.

The rima glottidis is the opening between the arytenoids and represents a narrowing in the airway when laryngeal paralysis occurs.  Heat and exercise increase the rate of flow through the upper airway and the narrowing at the rima glottidis results in a region of low pressure at the rima due to the Venturi effect.  The result is that increased respiratory effort results in further narrowing of the rima glottidis and further dyspnea.  The patient experiences increased stress and temperature resulting in an additional increase in respiratory effort and further narrowing of the rima glottidis. Ultimately the end results of laryngeal paralysis particularly in periods of increased heat and exercise are hypoxia, hyperthermia and moderate to severe stress.  A secondary result can be aspiration due to ineffective laryngeal adduction and eventually aspiration pneumonia.

The association between acquired laryngeal paralysis and generalized neurologic disease remains controversial.  Several studies have suggested that a significant percentage of dogs with laryngeal paralysis may have or develop generalized neurologic signs and that those with generalized neurologic disease at the time of diagnosis have a greater risk of complication and poorer prognosis than those without.

Infrequently, dogs may present with congenital laryngeal paralysis.  The most common breeds identified with laryngeal paralysis are Bouviers des Flandres and Siberian huskies. Many dogs with congenital laryngeal paralysis are younger and frequently show signs of other neurologic disease.  Many of these patients will have progressive neurologic deterioration and owners should be cautioned of this likelihood prior to electing surgery.

Diagnosis

There is a broad variety of presentations of laryngeal paralysis although most dogs are older and males are two to four time more commonly affected than females. The Labrador retriever is the most common breed presented although other breeds such as golden retrievers and spaniels are also over-represented. Traumatic laryngeal paralysis secondary to bite wounds or other cervical trauma may present in any breed of dog or cat.

History

Owners often report progressive exercise intolerance, increased respiratory effort in the heat, increased respiratory noise and intermittent gagging. Mild cases may only result in clinical signs or increased noise during significant exertion. We commonly see two groups of presentations.  In the first group the patients present with a normal respiratory effort and attitude but a distinct raspy upper airway noise is evident. There may be a history of gagging and increased respiratory noise when sleeping. The second group presents as a respiratory emergency with severe upper airway distress and possible hyperthermia.

Treatment of patients in severe upper airway distress is directed at supplementing oxygen, sedation, and cooling if indicated by hyperthermia.  Treatment of the stress by sedation is probably the single most important action to stop the cycle of hypoventilation and subsequent increased respiratory effort triggered by stress.  In the most severe cases, we will anesthetize and intubate the patient and either recover them from the anesthesia slowly and continue sedation or take them immediately to surgery for a laryngeal tie back.

Thoracic radiographs should be obtained in all cases of suspected laryngeal paralysis to evaluate for aspiration pneumonia or co-morbidities.

Definitive diagnosis of laryngeal paralysis is made by laryngoscopy with the patient under light anesthesia. We avoid all premedications during this procedure to decrease the risk of false positive results. We generally use i.v. propofol alone and want the patient at a plane of anesthesia where they are actively taking deep breaths on their own.  The oral cavity and naso- and oropharynx are examined for any masses or other disease. The arytenoid function is then carefully evaluated in conjunction with monitoring the patient’s inspiration and expiration. It is critical to coordinate the respiration with the movement of the arytenoids to avoid a false negative test.  Other methods of diagnosis including ultrasound or flexible endoscopy have not proven as effective as laryngoscopy.

Treatment

Medical treatment of mild laryngeal paralysis is often directed at modification of lifestyle. Exercise moderation should be prescribed particularly in warmer weather and weight management may aid in reducing the risk of hyperthermia and overexertion. Elevated feeding and decreasing the speed of water consumption with water bowl obstacles may decrease the risk of aspiration.

Surgical treatment is directed at enlarging the rima glottidis or bypassing the larynx by permanent tracheostomy.  Most surgeons elect unilateral arytenoid lateralization (tie back procedure) due to the high success rate and lower complication rate than other procedures.

A permanent tracheostomy should not be necessary for treatment of laryngeal paralysis except in rare cases of laryngeal collapse.  Tracheostomies require regular care by the owners and may contribute to additional tracheal disease.

Partial laryngectomy may be performed by an oral approach or ventral approach and may utilize laser or routine hand instruments.  Complications including webbing and subsequent airway obstruction can be severe and the degree of airway opening is less predictable than with the tie back procedure.

Unilateral arytenoid lateralization (tie back) is the most common surgical procedure for laryngeal paralysis. A lateral skin incision is made over one side of the larynx and the cricoarytenoidius dorsalis muscle is replaced with a non-absorbable suture that holds one of the arytenoids in permanent abduction.  Bilateral lateralization is rarely indicated.  The surgical procedure is approximately 45 minutes to an hour and the rima glottidis is checked during the procedure to ensure adequate opening. We use a non-absorbable braided suture due to its strength and the size and curvature of the needle.  Unlike many surgical procedures, the tie back procedure is based more on palpation than vision and the nature of working in a very tight anatomical region necessitates a perfect needle size and curvature.

Postoperative care and complications

Patients undergoing arytenoid lateralization have instant relief of the airway obstruction and demonstrate a dramatic difference in attitude and respiration within minutes of anesthetic recovery.  We take numerous precautions to limit aspiration pneumonia during the recovery period including the use of antacids, broad spectrum antibiotics and metoclopramide in addition to recovering the patients with an elevated head and thorax. These patients demonstrate very little surgical pain and, like most Labradors, are eager to eat as soon as permitted.  We feed soft meatball shaped food for the first two weeks and then gradually return them to their normal diets.

The most common complication of the tie back procedure is seroma formation at the incision site due to microvasculature and dead space formation.  Aspiration pneumonia is reported any time postoperatively in 10 to 20% of cases although our records suggest our hospital rate is closer to 6%. Most aspiration pneumonia can be medically treated on an out patient bases.  We are aware of only two cases of elective euthanasia due to aspiration pneumonia from patients in our hospital.  Over a 10-year period we have re-operated 2 patients after failure of the cartilage or suture with successful revision in both cases. Initial failure may be due to inappropriate suture placement or brittle cartilage. Owners should also be informed that following the tie back procedure, dogs will not be able to generate a normal bark sound although many have had a voice change preoperatively as well.

The overall survival rate following tie back surgery is 94%, 90% and 85% at 1,2 and 3 years postoperatively respectively.  The overall client satisfaction rate is greater than 95% in our hospital. Successful surgical treatment of laryngeal paralysis can eliminate or drastically reduce the risk of upper airway distress and hyperthermia and significantly improve exercise tolerance.  The decrease in stress to the owners and the patient is immeasurable.  While the risk of complications with tie back surgery can never be completely eliminated, the high client satisfaction rate and significant survival times support the use of surgical treatment in the majority of patients.

Elbow Mass in a Dog

Written by Marielle Goossens, DVM, DACVIM, Noelle Bergman, DVM, MS, DACVIM (Oncology) and Kendra E.F. Knapik, DVM, DACVIM (Oncology)

 

Phineas, a 7-year-old Flat Coated Retriever, was presented to Peak for evaluation of left thoracic limb lameness of 10 month duration. During physical examination, marked soft tissue swelling and decreased range of motion of the left elbow was noted. Radiographs of the left elbow showed marked bone proliferation associated with the elbow joint. The radiographic and physical exam findings were most consistent with a mass arising from the elbow joint. Since neoplasia was the top differential diagnosis for a mass in the elbow of a middle-aged Flat Coated Retriever, thoracic radiographs were ordered. No evidence of intrathoracic metastasis was observed. A CT scan was performed next, and a mass enveloping the left elbow was confirmed. An incisional biopsy of the mass was taken prior to recovering Phineas from anesthesia.
 

 
The histopathologic diagnosis was a sarcoma, and the pathologist was most suspicious that this tumor was of histiocytic origin given the signalment of the patient, tumor location, and the microscopic features of the biopsy. The mitotic index was 14, and there was marked anisocytosis and anisokaryosis with multifocal cytomegaly, karyomegaly, and multinucleated giant cells. The neoplastic cells extensively invaded the adjacent skeletal muscle. Other differentials for a tumor arising from the joint that were considered included a synovial cell sarcoma and other soft tissue sarcomas. Phineas was referred to the Oncology Service for consultation regarding the biopsy findings.

 

Diagnostic Work Up

Special stains were ordered to confirm the diagnosis of histiocytic sarcoma. The neoplastic cells were diffusely positive for both CD18 and CD204, which are two markers for cells of histiocytic origin.

Histiocytic sarcoma (HS) is a malignant neoplasm of histiocytic cells. Dog breeds that are overrepresented with this neoplasm include Bernese Mountain Dogs, Flat-Coated Retrievers, and Rottweilers.These tumors can present in two main forms: localized and disseminated. The localized form involves a single primary tumor arising from a joint, cutaneous or subcutaneous tissue, lung, or essentially anywhere in the body. Patients with the disseminated form present with an advanced stage of disease and often with multiple visceral organs involved. Most commonly the liver, spleen, lungs, and lymph node are affected. The prognosis for dogs with the localized form of the disease is significantly better than the disseminated form. The localized form of HS has been shown to have a median survival time beyond 500 days following treatment compared to several months with the disseminated form. Commonly, patients with the disseminated form present with signs of systemic illness including weight loss, anorexia, vomiting, and occasionally, fever. Despite the superior prognosis, localized histiocytic sarcomas still have a high risk of metastasis to lymph nodes, lung, liver, spleen, and other organs.

Treatment and Follow-up

Given the high risk of metastasis, an abdominal ultrasound was recommended for Phineas. No evidence of abdominal metastasis was observed. Since Phineas’ disease was confined to his elbow based on the staging tests, a left forelimb amputation was recommended followed by chemotherapy with CCNU (lomustine). Periarticular forms of HS have been shown to have a significantly improved prognosis over HS arising from other organs. Periarticular HS that has not metastasized has been shown to have a median survival time of 980 days following treatment in one study. While amputation is the treatment of choice, palliative radiation therapy can also be used to help control pain in patients that are not candidates for amputation.

CCNU is the chemotherapy drug of choice for HS. The response rate in the gross disease setting has been reported to be 40-60%. For patients that develop progression of their disease with CCNU, doxorubicin with zoledronate (a bisphosphonate) is another option. This combination of drugs has displayed synergistic cell death in in vitro studies evaluating HS. Anecdotally, impressive responses have been observed with this drug combination in practice as well.

Phineas recovered well from his forelimb amputation despite concurrent orthopedic diseases (elbow dysplasia and history of a TPLO on a hind limb). His orthopedic diseases were managed with a combination of carprofen, gabapentin, amantadine, and Dasaquin. Following limb amputation, Phineas was started on chemotherapy. He received 6 doses, which were administered every 3 weeks. Restaging tests with thoracic radiographs and abdominal ultrasound were performed in the middle of the chemotherapy protocol and again at the end. No evidence of metastatic disease was observed at either time point. We have continued to monitor Phineas with these staging tests every 3 months. Phineas was diagnosed in August 2016 and was clear of disease on his most recent staging tests.


REFERENCES:
  1. Withrow, S.J., D.M. Vail, R.L. Page. Small Animal Clinical Oncology. St. Louis: Elsevier Saunders, 2013. Print.
  2. Klahn, SL, BE Kitchell, NG Dervisis. Evaluation and comparison of outcomes in dogs with periarticular and nonperiarticular histiocytic sarcoma. J Am Vet Med Assoc 239.1 (2011): 90-96.
  3. Skorupski, KA, et al. CCNU for the treatment of dogs with histiocytic sarcoma. J Vet Intern Med 21.1 (2007): 121-126.
  1. Skorupski, KA, et al. Long-term survival in dogs with localized histiocytic sarcoma treated with CCNU as an adjuvant to local therapy. Vet Comp Oncol 7.2 (2009): 139-144.
  1. Hafeman, SD, D Varland, SW Dow. Bisphosphonates significantly increase the activity of doxorubicin or vincristine against canine malignant histiocytosis cells. Vet Comp Oncol 10.1 (2012): 44-56.

A Lameness Puzzle

Written by Marielle Goossens, DVM, DACVIM

 

Presentation and Physical Exam

Daniel, a 3 year old, male, castrated, Golden Retriever presented to Dr. Kurt Schulz at Peak’s Surgery service for evaluation of a 2 month history of worsening lameness of the right hind leg. Radiographs of the right knee joint had only shown some soft tissue swelling and no other abnormalities. Daniel had no other clinical problems. The lameness improved on Rimadyl.

Physical exam revealed a non-weight bearing lameness of the right hind leg with swelling of the right knee joint. The only other abnormality on physical exam was a II/VI right systolic heart murmur.

Diagnostic work up

Dr. Schulz performed joint taps which showed neutrophilic inflammation of the right knee joint and normal joint fluid cytology in the other joints (total nucleated cell count of 19,490 with 55% neutrophils, 30% large mononuclear cells and 15% small to intermediate size lymphocytes). Culture of the joint fluid was negative.

A vector borne disease profile was submitted to NCSU and was negative for all tested diseases, including tick-borne diseases.

Daniel was transferred to Dr. Marielle Goossens in the Peak Internal Medicine service for further work up of the neutrophilic mono arthritis. A search was started for an underlying disease that could have triggered the neutrophilic inflammation in the right knee joint.

Patient Workup:

    • A full profile and urinalysis at Idexx only showed a mildly increased ALT of 145 and the remainder of all values were normal.
    • An ultrasound of the abdomen was normal.
    • Thoracic radiographs were normal.
    • Cardiac work up by Dr. Don Brown showed mild ventricular hypertrophy and some aortic valve insufficiency, but no evidence of endocarditis. Systemic blood pressure was normal.
    • A Blastomycosis urine antigen test was sent to Mira Vista laboratories and showed a weak positive test, below the limit of quantification.
    • After speaking with Mira Vista Diagnostics about these results, Blastomycosis and Histoplasmosis serum antibody EIA testing was performed.
    • While waiting for these results, repeat radiographs were obtained of the right knee joint. They showed right stifle effusion and evidence of active osseus lesions at the distal lateral metaphysis and increased medullary opacity, which had not been observed on radiographs 2 months prior (fig. 1).
    • A CT and bone biopsy of the right knee joint were performed. Histopathology showed neutrophilic to granulomatous osteomyelitis with new bone formation and osteolysis.
    • Special stains were performed for fungal organisms and showed low numbers of broad based budding fungal organisms, consistent with Blastomyces Dermatitidis (fig. 2).

Fig. 1: Radiograph of the knee joints showing the subtle bone changes in the right knee joint.

Fig. 2: Histopathology of the bone biopsy showing the broad based fungal organisms consistent with Blastomycosis Dermatitidis.

At the same time as the biopsy results came back, the antibody titers also came back from Mira Vista Diagnostics. The Blastomycosis antibody was negative, but the Histoplasma IgG antibody EIA was high positive.

Treatment and Follow up

Daniel was started on itraconazole after the bone biopsy was taken prior to receiving the results back , as the suspicion for blastomycosis was high. He was treated with generic itraconazole at 5 mg/kg PO once a day. His lameness started to improve within about 2 weeks after starting this treatment and the pain relief medications that he had been on, were gradually discontinued.

Daniel was treated with itraconazole for a total of 8 months. We treated him for 1 month beyond the point of when no further improvement of the boney lesions on the radiographs, could be determined. His urine blastomycosis antigen level had returned to negative prior to this time.

Daniel is now about 2.5 months out after finishing the itraconazole. His first recheck urine antigen level was negative. So far, he is doing well. His urine blastomycosis level antigen test will be performed again at 3, 6, 9 and 12 months after he finished the itraconazole, as relapse of the blastomycosis is common during the first year after finishing treatment. Repeat knee radiographs will also be taken intermittently over this coming year, to make sure that the boney changes remain quiescent.

Case Discussion

Blastomycosis is a diagnosis that is being made more frequently in Vermont and upstate New York over the past several years. What is interesting about Daniel’s case is that he presented with lameness in just one leg and he was not systemically ill. Initially, the only change in him was a swollen, painful knee joint with neutrophilic inflammation in that one joint, with no radiographic changes for the first 2 months of his lameness. We have seen several other cases that presented with neutrophilic inflammation in one joint with or without radiographic changes, that ended up being diagnosed with blastomycosis.

Cases like Daniel’s make us realize, that we need to have the differential of blastomycosis on our rule-out lists for many cases that present to us.

As most of you know, blastomycosis can present itself in our patients in many ways, including:

    • Panophthalmitis
    • Uveitis
    • Mass effects
    • Lymphadenopathy
    • Draining tracts
    • Bone lysis
    • Classical presentation of blastomycosis in the lungs (snow storm effect).

The diagnosis is often straightforward by performing the urine blastomycosis antigen test. Sensitivity of this test is over 90%, but false negatives do occur, and we have seen these negatives several times at Peak.

If the urine antigen test is negative, consider cytology and/or histopathology as these techniques are considered the gold standard method for diagnosis. Antibody detection can also be used in antigen negative cases, as we performed in Daniel.

The sensitivity of the AGID method has ranged from 17% to 83% and experience in clinical practice has been unfavorable. The sensitivity of the EIA method is superior to AGID, supporting its use as an aid in the diagnosis of blastomycosis in antigen negative cases.

A Final Note on Blastomycosis

We have seen many cases being treated successfully after the blastomycosis diagnosis. Blastomycosis in the lungs or in the central nervous system, has a higher chance of an unsuccessful treatment. There is evidence that longer treatment may reduce relapse. Relapse rates of 18-25% are listed in the first year after finishing treatment. Recommendations have been made that at least a four to six months course of itraconazole should be given to reduce the likelihood of relapse.

At Peak, we recommended continuing therapy one month beyond resolution of all clinical findings, including eye exam, chest radiographs or bony changes, and one month after the urinary antigen was negative. We then check urine antigen levels at 1, 3, 6, 9, and 12 months after finishing treatment, to make sure we catch a relapse of the blastomycosis prior to the development of symptoms.

Canine Unicompartmental Elbow Resurfacing (CUE)

,
Severe elbow arthritis

Severe elbow arthritis. The pink area is exposed bone where the cartilage has been worn away

About severe elbow arthritis in dogs

Osteoarthritis from coronoid disease and other forms of elbow dysplasia may result in complete loss of cartilage on the weight-bearing surfaces of the medial joint structures resulting in what veterinarians call Medial Compartment Disease (MCD). This is the “end stage” form of elbow dysplasia where the inside part of the joint collapses with eventual grinding of bone on bone. Interestingly and importantly, the larger lateral (outside) part of the elbow joint appears normal in the vast majority of patients.  Medial compartment disease can be diagnosed in dogs as young as 6 months of age or may become apparent in any age after that.

How can medial compartment disease be treated?

Options such as oral medications, joint injections, and physical therapy may be beneficial in some cases for at least a period of time and should be discussed with your veterinarian. When surgical treatment is deemed necessary, as is often the case, the Canine Unicompartmental Elbow (CUE) is a safe and effective option to consider. The CUE was developed by Dr. Schulz (Peak) and Dr. Cook (University of Missouri) with the Arthrex corporation. It was developed as a treatment for MCD for dogs in which arthroscopic treatment and the nonsurgical options are no longer successful. By focusing on the specific area of disease (the medial compartment), the CUE implant provides a less invasive, bone-sparing option for resurfacing the bone-on-bone medial compartment while preserving the dog’s own “good” cartilage in the lateral compartment. This medial resurfacing procedure reduces or eliminates the pain and lameness that was caused by the bone-on-bone grinding.

Cobalt chrome and titanium implant

This implant is made of cobalt chrome and titanium and is inserted in the upper bone (humerus) of the joint to restore the gliding surface

Is the CUE a major surgery?

The CUE procedure is an open surgery but only takes about one hour to perform. Unlike total elbow replacements it does not require major bone cutting and a large surgical approach. The recovery from CUE is much faster than from total elbow replacements and the outcome appears to be much better.

Polyethylene and titanium implant

This implant is made of polyethylene and titanium and is placed in the lower bone (ulna) of the elbow joint. It articulates with the other implant resulting in a low friction pain free articulation for the elbow.

What can I expect after CUE surgery?

You will be sent home with antibiotics and pain-relieving medications for your dog. A bandage will be placed on the limb, which you will need to keep clean and dry. The bandage will be changed after one week and maintained for at least two weeks after surgery. Sutures will be removed approximately two weeks after the procedure. Your dog must be restricted to rest in a kennel or crate, with controlled leash walking only, for eight weeks after surgery. Follow-up examination and assessment of healing will be performed 8-10 weeks after the procedure, at which time rehabilitation exercises will be initiated to allow a progressive return to full activity levels by six months after surgery. Full athletic function is not expected until three to six months after surgery, at which time a final assessment will be performed.

Our client information sheet on the CUE can be downloaded here:

  Canine Unicompartmental Elbow Resurfacing (CUE)

Laryngeal Paralysis

,

Written by Kurt S. Schulz, DVM, DACVS

Laryngeal paralysis is a common upper respiratory disease of dogs. It most often affects large breed dogs such as Labrador retrievers and Golden retrievers but it can affect any dog of any breed or size. Normally when a dog inhales the larynx (voice box) opens to allow air into the trachea and lungs. The larynx closes between breaths to prevent food and water from going into the trachea and lungs. In laryngeal paralysis the muscle that opens the larynx stops functioning. This results in a very narrow passageway to get air into the lungs instead of the normal wide-open larynx. Dogs with laryngeal paralysis have difficulty inhaling and the harder they try the more difficult it becomes to inhale adequate air.

Fig.1 – Views of the larynx. The top view is of a normal larynx. The middle is a laryngeal opening in a dog with laryngeal paralysis. The bottom is the appearance of the larynx following a tie back procedure.

What are the signs of laryngeal paralysis?

Several signs may suggest that a dog has laryngeal paralysis:

  • Harsh breathing – laryngeal paralysis usually leads to a characteristic harsh breathing sound that gets louder with exercise. This noise is caused by air passing through the narrow space in the larynx.
  • Voice change – laryngeal paralysis will often cause a change in a dogs bark, making it sound more hoarse.
  • Coughing – Some dogs may have a cough with laryngeal paralysis that sounds like it comes from the throat.
  • Gagging – Many dogs with laryngeal paralysis may gag when they eat or drink.

How is laryngeal paralysis treated?

Laryngeal paralysis is best treated by surgery. There are several surgical options although one procedure, the “tie-back” is the most accepted and most commonly performed by Board Certified surgeons.

Tie back

In the tie back procedure the larynx is approached through the side of the neck. The failed muscle is then identified and replaced with a suture to permanently open the larynx on one side. This procedure produces the best airway with the least complications of any of the available surgeries.

Partial arytenoidectomy

In this procedure the portions of the larynx that obstruct the airway (the arytenoids) are removed by scissor or laser through the mouth. This procedure is not recommended because of the high risk of scar formation that can severely obstruct the airway.

Castellated laryngofissure

This procedure enlarges the airway through a complicated series of incisions and reconstructions from the underside of the neck. There have been no definitive advantages shown with this procedure and it is rarely performed.

Permanent tracheostomy

A permanent tracheostomy should only be performed when a tie back procedure will not correct the airway obstruction. Dogs with permanent tracheostomies cannot swim and may have other chronic airway complications.

For additional information about Laryngeal Paralysis: laryngeal paralysis