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.


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.


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 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.


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.


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.


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.


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.


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.

  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

TPLO Cruciate Repair


Cranial Cruciate Ligament Injury

Cranial cruciate ligament rupture (CCLR) is the most common orthopedic injury in dogs. In people, the same ligament is called the anterior cruciate ligament. In both species the ligament may stretch or tear, leading to pain and osteoarthritis. CCLR can make the menisci vulnerable to tearing, which is quite painful. The menisci are two small cushions of fibrocartilage that sit between the bones of the knee.

The signs of CCLR vary, but they include an acute onset of lameness followed by mild improvement but continued lameness. Other dogs experience a moderately progressive lameness particularly associated with exercise or lameness when the dog gets up after resting.


CCLR is first diagnosed by palpation (examination and manipulation by hand). X-rays are routinely taken in dogs with CCLR, but this disease cannot be diagnosed on x-rays because the ligament does not appear on radiographs.


Surgery is recommended for most dogs with CCLR. In very small dogs it is possible for the knee to improve in stability without surgery as the body lays down scar tissue, but in most dogs adequate stabilization of the knee will usually not be achieved, and the pain and lameness will continue.

More traditional surgical treatments of CCLR involve replacing of the ligament with either a natural or synthetic material. In these procedures, natural fibrous tissue, nylon suture, or wire is used to stabilize the knee. These procedures have been used for more than half a century, and the results are good in many cases. The main concern with these procedures is that the stabilizing material can stretch or break, after which the knee is stabilized by scar tissue. This may lead to a decrease in the range of motion of the joint. We recommend extracapsular suture surgery for smaller dogs (less than 35 pounds) or when medical or financial limitations prohibit performance of a Tibial Plateau Leveling Osteotomy (TPLO).

Tibial Plateau Leveling Osteotomy

The most widely used technique in treatment of CCLR by board certified surgeons is the TPLO. In this technique, the lower bone of the joint (tibia) is cut and rotated to eliminate the abnormal motion of the knee during normal activity. The advantage of this procedure is that it does not rely on materials that can stretch or break to stabilize the knee. We recommend TPLO in most of our medium and large patients and particularly in more active dogs.

How the TPLO Works

Studied have demonstrated that if the lower bone of the knee (the tibia) is steeply sloped at the level of the joint, the upper bone of the knee (the femur) is always sliding down the tibia. This constant sliding places strain on the cruciate ligament, possibly causing it to fail. The TPLO procedure corrects the tibial plateau angle to eliminate the sliding and the instability of the knee and the accompanying pain and slowing the progression of osteoarthritis.

Cruciate Surgery at Peak

Cruciate surgery at Peak Veterinary Referral Center is performed by a highly experienced and caring team who prioritize your pet’s welfare. Dr Schulz has been performing cruciate surgery including TPLO for over 15 years. He served as chief of surgery at the University of California and has published over 60 manuscripts in canine orthopedics. He is an author of several books including Small Animal Surgery, Small Animal Arthroscopy, and the Pet Lovers Guide to Joint Problems and Osteoarthritis.

At Peak we feel it is important to educate owners and help them make the best decision for their pet and their family. In many cases surgery may be performed the same day as your initial appointment.

Total Hip Replacement


Osteoarthritis is one of the most common diseases of dogs, affecting up to 25% of all dogs during their lifetime. The hip and knee are the most common locations but have dramatically different causes and treatments.

The majority of osteoarthritis of the hip is due to hip dyspla­sia. This disease is a result of genetics which leads to poor hip conformation and laxity and subluxation (loose joints) while the dog is young. As the dog ages the joints actually tighten up but the resulting poor fit of the joint (incongruence) leads to grinding of cartilage and inflammation of the joint. Many adult dogs with severe hip dysplasia and osteoarthritis have no normal cartilage remaining in their hip joint.

The common signs of osteoarthritis of the hips in dogs are limping and exercise intolerance. Exercise intolerance is actually the most common while fewer dogs actually limp with hip dysplasia.

There are two broad categories of management of hip dys­plasia and osteoarthritis in dogs. They are medical and surgical. It is important to remember that even when surgical management is elected, medical management may be necessary still. This is particularly true when one hip receives surgical therapy but the opposite side remains diseased.

Medical management

Medical management of hip dysplasia includes 5 treatment principles:

  • management of body weight
  • nutritional supplementation
  • moderation of exercise
  • physical therapy
  • medications


Surgery for hip dysplasia is indicated when medical man­agement no longer maintains quality of life and function. It may also be indicated when medical management causes complications. The decision to pursue surgical treatment should be made by the owner in consultation with the veterinarian but the owner must decide on quality of life.
There are two surgical options for the mature dog with hip osteoarthritis. They are femoral head and neck ostectomy (FHO) and total hip replacement (THR).


FHO is an excellent option in small dogs (and cats). In this surgery the ball of the ball and socket joint is removed. The hip then works by having the leg supported by the gluteal muscles. (This procedure was developed for treatment of hip infection in people.) Because of their small body weight small dogs and cats tolerate this procedure very well. In larger dogs the outcome is not always as good but it may be necessary for financial or medical (infection) reasons. Ultimately the outcome of this procedure is unpredictable but is probably improved by combining the procedure with professional physical therapy.


Total hip replacement has been performed in thousands of dogs in the US and the world. The outcome is generally excellent in 85% to 90% of dogs; however when complications occur they can be frustrating and expensive. Traditionally THR was always performed as late in life as possible because of concern for the implants wearing out. The development of cementless implants allows THR in patients as young as 8 months of age.

Tightrope Cruciate Repair


The Tightrope technique is an excellent alternative to the TPLO for treatment of cruciate ligament rupture in dogs of any size. This technique works similar to older suture techniques but is significantly stronger and simpler. The tightrope technique is stronger because it relies on small bone tunnels and stainless steel surgical “buttons” to secure the suture. This is much stronger than traditional methods of securing the suture. In addition, the suture is human orthopedic surgical grade material which is far superior to traditional materials used to stabilize the knee of dogs.

The Tightrope technique is an alternative for clients who are concerned with the bone cutting required in the TPLO.  The Tightrope can be performed with arthroscopic assistance so only a few small incisions are required.

Studies to date suggest that the Tightrope has  excellent results similar to those of the TPLO.

Sliding Humeral Osteotomy


A new Treatment for Elbow Dysplasia in Dogs

Elbow dysplasia and the secondary arthritis are the most common causes of foreleg lameness in dogs. Fragmented coronoid process (FCP) is the most common form of elbow dysplasia in dogs. In this disease, a fragment of bone and cartilage of one of the bones of the elbow joint (ulna) is broken off. More important, the rest of the joint may be normal or there may be additional cartilage damage, including severe full-thickness cartilage loss. Damage to the cartilage in dogs with elbow dysplasia is called Medial Compartment Disease because it commonly results in severe erosion of the cartilage of the medial aspect of the joint.

Diagnosis of FCP and Medial Compartment disease (MCD)

Diagnosis of FCP and MCP can be challenging. The diagnosis is initially based on a careful orthopedic examination. X-rays (radiology) are of limited use in the diagnosis of FCP. The FCP fragment and damage to the cartilage cannot be seen on x-rays. We recommend arthroscopy for the diagnosis of FCP and MCD because it allows early and accurate diagnosis and treatment

Dogs with Medial Compartment Disease usually require more continuous medical treatment of osteoarthritis and owners should consider additional surgical treatment options.

Advanced surgical treatments of Medial Compartment Disease include Sliding Humeral Osteotomy (SHO) and total elbow replacement.

Total elbow replacement may be indicated when the cartilage is severely damaged throughout the elbow joint. Numerous total elbow replacements have been designed over that last 15 years and to date none has been proven to be safe and effective enough for routine use.

Sliding Humeral Osteotomy

Sliding Humeral Osteotomy (SHO) was developed in the Orthopedic Research Laboratory of the University of Californita by Dr Schulz. This procedure is based on similar procedures that are performed on people for arthritis of the knee. The procedure realigns the limb to shift the forces off of the area of cartilage damage and back on to healthy cartilage. This relieves the pain of grinding of bone on bone and gives the damaged joint an opportunity to heal.

The sliding humeral osteotomy procedure is the result of almost 10 years of laboratory research. These studies have demonstrated that the sliding humeral osteotomy significantly decreases joint pressure in the medial side of the elbow joint.

Clinical results

Over the last 3 years the SHO procedure has been performed in over 70 dogs. Careful clinical studies have been performed to evaluate the efficacy of this procedure. The majority of dogs undergoing SHO have decreased lameness by 12 weeks postoperatively with many dogs having no visible lameness at a 26 week evaluation. The owner satisfaction rate following SHO has been nearly unanimous.

SHO surgeons

Surgeons performing the SHO procedure are all highly experienced orthopedic veterinary surgeons. They have completed a course covering the theory, indications, and application of the SHO technique.