Dilated cardiomyopathy, or DCM, is characterized by an increased heart size due to weakened pumping ability of the heart muscle. In many patients, DCM eventually leads to heart failure and death.

Multiple studies have recently revealed a correlation between certain dietary ingredients and the development of DCM in dogs. In particular, an association between DCM and the feeding of grain–free diets is suspected, but not yet definitively proven.

In a recent article in JAVMA, specialists from veterinary colleges throughout the U.S. explained what is currently understood about diet-associated DCM. The FDA Center for Veterinary Medicine and Veterinary Laboratory Investigation and Response Network are also currently working with veterinary cardiologists and nutritionists around the world to identify the complex causes of this condition².

The Relationship Between Diet & Dilated Cardiomyopathy

In the 1980s, an association between DCM and diet was first identified in cats affected with the condition³. Eventually, researchers discovered that taurine deficiency was the culprit, as cases could be effectively reversed with oral taurine supplementation and dietary modification.

Canine DCM is traditionally considered an inherited condition that predominantly affects certain large and giant dog breeds, such as the Doberman, Great Dane, and Irish Wolfhound. Unlike with DCM due to taurine deficiency, supplementing taurine in the diet is not an effective treatment for genetically caused DCM.

Since the mid–1990s, however, reports have been increasing in unlikely dog breeds, as well as mixed–breed dogs. In a worldwide survey of veterinary cardiologists, Ryan Fries, D.V.M., discovered more than 240 potential cases of diet–associated DCM over a 2–year period¹. Most of the affected dogs were mixed–breeds, while frequently affected breeds included the Golden Retriever, Labrador Retriever, German Shepherd Dog and Cocker Spaniel.

“BEG” Diets

Eventually, researchers determined that many of the affected dogs were fed diets containing certain ingredients, often for months to years before developing clinical signs. Collectively, these were termed “BEG” diets, standing for Boutique (i.e., small manufacturer), Exotic protein sources, and/or Grain–free.

BEG and homemade diets have recently gained popularity in the pet trade. Many pet owners switch to BEG diets in the pursuit of wholesome, high–quality ingredients, and some grain–free diets are even marketed specifically for the management of certain health conditions, such as food allergy.

While BEG diets are appealing for well–intended owners, they often lack scientific support. Boutique diets made by small manufacturers are not always tested to meet the Association of American Feed Control Officials (AAFCO) standards or World Small Animal Veterinary Association (WSAVA) guidelines; therefore, they may be missing one or more important nutrients.

Exotic ingredients in diets fed to DCM–affected dogs have included novel meat sources (such as kangaroo, duck, buffalo and venison), flaxseed, fruit, probiotics, and starch and fiber derivatives. Grain–free diets frequently list peas, lentils, legume seeds or potatoes as the main ingredient.

Dr. Fries’ cardiologist survey revealed that many affected dogs had low blood or plasma taurine levels¹. It’s important to note that not all dogs with diet–associated DCM were deficient in taurine. Instead, they may have been affected by other, currently unknown dietary factors. The FDA is currently investigating possible causes of diet–associated DCM, such as a deficiency or decreased bioavailability of another nutrient or, alternatively, the presence of a cardiotoxin in the diet².

DCM In Golden Retrievers

A recent study suggests that Golden Retrievers may be particularly susceptible to diet–associated DCM. In the study, 24 client–owned Golden Retrievers were diagnosed with DCM and taurine deficiency, which the authors defined as <250 nmol/mL of taurine in whole blood⁴. Eleven of the dogs were severely affected and displayed signs of congestive heart failure that necessitated diuretic therapy.

At the time of diagnosis, all dogs were fed diets that did not meet AAFCO standards or WSAVA guidelines. Out of the 13 identified diets, 12 were advertised as grain–free, and 10 of these instead contained a legume as the main ingredient. After dietary modification and supplemental taurine, nearly all dogs showed significant clinical improvement, and congestive heart failure resolved in 9 of 11 dogs. This encouraging outcome suggests that diet-associated DCM is largely reversible in dogs when the underlying cause is addressed.

What to Do If You Have a Suspect Case

The FDA currently recommends reporting suspected cases of diet–associated DCM. Diagnostic workup should include a review of the brand, product and flavor of the main diet, as well as any treats and supplements. Look for these key factors: 1) BEG ingredients, 2) low protein, 3) high fiber, 4) vegetarian, 5) vegan, or 6) homemade diets.

Whole–blood taurine levels should be measured to examine the patient’s long–term taurine status. However, it is worth noting that Golden Retrievers with diet–associated DCM often maintained whole–blood taurine levels of 200–250 nmol/L, staying within the low end of the reference range for dogs⁴.

As recent studies suggest, dietary change and supplemental taurine are the mainstays of treatment, though it may take several months to observe patient improvement. Echocardiogram is the most sensitive method for assessing a recovering patient’s cardiac status during followup⁴.

Conclusions

The FDA and other study groups are still working to fully understand the relationship between dietary ingredients and the development of DCM in canine patients. Until more information is known, dietary assessment and case reporting should be performed for newly diagnosed cases of DCM, particularly for those dogs not belonging to high–risk breeds for genetic DCM. Veterinary practitioners can also help reduce the risk of diet–associated DCM by advising pet owners to only feed diets that meet AAFCO and WSAVA guidelines. +

References

¹ Freeman LM, Stern JA, Fries R, Adin DB, Rush JE. Diet-associated dilated cardiomyopathy in dogs: what do we know? JAVMA. 2018; 253(11): 1390-1394.

² US FDA. FDA investigating potential connections between diet and cases of canine heart disease. July 12, 2018. www.fda.gov/AnimalVeterinary/NewsEvents/CVMUpdates/ ucm613305.htm. (accessed December 13, 2018)

³ Pion PD, Kittleson MD, Rogers QR, Morris JG. Myocardial failure in cats associated with low plasma taurine: a reversible cardiomyopathy. Science. 1987; 237: 764–768.

⁴ Kaplan JL, Stern JA, Fascetti AJ, Larsen JA, Skolnik H, Peddle GD, Kienle RD, Waxman A, Cocchiaro M, Gunther-Harrington CT, Klose T, LaFauci K, Lefbom B, Machen Lamy M, Malakoff R, Nishimura S, Oldach M, Rosenthal S, Stauthammer C, O’Sullivan L, Visser LC, William R, Ontiveros E. Taurine deficiency and dilated cardiomyopathy in golden retrievers fed commercial diets. PLoS ONE. 2018; 13(12): e0209112. https://doi.org/10.1371/journal.pone.0209112

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Laser therapy is an increasingly popular tool used to help manage a variety of veterinary patient concerns, including postoperative pain, arthritis and slow wound healing. Laser therapy is performed on companion animals, horses and even exotic species, and is widely accessible to general practitioners.

How Laser Therapy Works

Low–level laser therapy (LLLT), also known as photobiomodulation therapy, uses light emitted at a specific wavelength to stimulate cellular processes. Another term for LLLT is “cold laser therapy”, as the laser produces only a minimal amount of heat and energy compared to surgical lasers. The depth of light penetration is determined by the light’s wavelength, with superficial tissues absorbing light at lower wavelengths compared to deep tissues. Use of different wavelengths, light doses and intensities can greatly influence how LLLT interacts with target tissues.

All lasers are classified by the amount of power they deliver, and therapeutic lasers in veterinary medicine belong to either class 3B (LLLT) or class 4 (high-power laser), with the latter having a higher risk of side effects including thermal tissue damage. The rest of this article will focus on LLLT (class 3B).

The many benefits of LLLT are not yet fully understood. At a cellular level, molecules known as “photoacceptors” use photon energy emitted by the laser light to enter an excited state. Certain cellular activities, including increased mitochondrial ATP and cell membrane permeability, as well as reduced cellular apoptosis and proinflammatory cytokine release are stimulated. These cellular activities promote formation of granulation tissue, collagen, bone and blood vessels, leading to increased delivery of oxygen and immune cells to the target tissues.

Applications in Veterinary Medicine

LLLT has been studied extensively in human medicine; however, there is a relative lack of research-based literature examining LLLT for veterinary use. Currently, there are no standard protocols for laser therapy in veterinary medicine, and the optimal parameters for different animal species are still unknown. Therefore, dosage settings are typically based on manufacturer-specific recommendations, rather than on established guidelines for best practices.

Most experts agree this area needs more research before we can understand laser therapy’s full potential in veterinary medicine. However, a safe starting point is to use parameters that have exhibited positive effects in the same species in peer–reviewed literature. Then, adjust doses according to the individual patient’s response to treatment. Many newer, veterinary–specific laser units also contain software to alter dosing parameters according to patient species, size, weight and coat color.

LLLT performs best when used as one part of a multimodal treatment program utilizing pharmaceutical and non–pharmaceutical components. Potential applications for LLLT use include adjunct treatment of IVDD, surgical incisions, slow-healing wounds, laminitis, anterior cruciate ligament rupture, edema and other acute and chronic issues.

Safety Considerations

While LLLT is generally considered a safe therapy, its use is contraindicated over areas of neoplastic tissue, endocrine tissue, active hemorrhage, open epiphyseal plates and gonads. The use of standardized eye protection is essential for humans and animals in the treatment room to avoid retinal damage from the laser.

What to Know Before Buying

A good–quality laser unit is not inexpensive, so it’s best to do your homework before purchasing one. Start by researching units that meet international laser safety standards and are made by manufacturers offering training and technical support for veterinary use.

Laser therapy typically offers an excellent return on investment. A trained veterinary technician or nurse can perform treatments, and most patients tolerate the short, painless sessions well with minimal restraint. Sessions typically occur frequently at first and then are gradually spaced out for chronic conditions.

Pricing can be based on treatment site or appointment time length, with pre–paid packages for multiple sessions. As many clients are unfamiliar with laser therapy, they will appreciate educational materials, as well as individualized progress reports via pictures and videos.

In conclusion, laser therapy is a promising modality to incorporate into general practice. While continued research is needed to establish standardized protocols for different species and applications, LLLT has a wide safety margin, is relatively non–invasive, and offers a variety of potential applications from patient rehabilitation to management of geriatric pain. Purchase of a unit, together with appropriate training of staff and patient selection, can provide a benefit to patient care and also improve your bottom–line.+

Reference:

Riegel RJ, Godbold Jr JC, eds. Laser Therapy in Veterinary Medicine: Photobiomodulation. West Sussex, UK: Wiley Blackwell, 2017.

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