Renal Replacement Therapies

Hemodialysis

Today, only four hemodialysis facilities exist in the US for ailing pets - two at UC Davis, one at the Animal Medical Center in New York City, and one at Tufts University Foster Hospital for Small Animals in North Grafton, Mass. Most of the machines used were originally for humans, but they are easily programmed for animals. In dogs, pediatric equipment is used to hook the patient onto the hemodialysis machines.

Typically, dogs are treated for antifreeze poisoning (45% of the population), leptospirosis (a contagious bacterial disease that affects the liver and kidneys), pancreatitis, and liver failure. Unfortunately, the survival rate for hemodialysis dogs that have antifreeze poisoning is only around 15%. The survival rate for leptospirosis, on the other hand, is arouns 80 to 90%.

The cost for a dog, with lab work and intensive care treatment, is around $5,000-$8,000 for 3-4 weeks. The individual treatments cost about $375.

Kidney Transplant

The current success rate for canine kidney transplants is about 40 percent, which is drastically lower than human figures. The main cause of failure is not rejection, but the associated symptoms of renal failure. If a transplant is preferred rather than dialysis, dogs with antifreeze poisoning require a period of stabilization prior to surgery.

Potential renal transplant candidates must not have the following health problems:

  1. cardiac disease that produces significant hemodynamic compromise
  2. urinary tract infection (see qualifications above)
  3. inflammatory bowel disease
  4. heartworm disease
  5. neoplasia – tumor growth
  6. diabetes or Cushing's disease
  7. poor body condition
  8. Irritable temperament

The recipients also cannot have any systemic organ diseases other than renal failure. Dogs with urinary tract infections may be considered if they are treated and have two subsequent negative urine cultures and pass a cyclosporine test.

Typically, unowned sogs at the surgery facility are used for transplants. The owner will be required to pay for all screening tests used to assess the donor canine, and sometimes the owner will also be required to adopt and provide a lifelong home for the donor regardless of the outcome of the transplant procedure. Just like in humans, dogs can live perfectly healthy lives with one kidney. The donor must be less than six years old and be free of any systemic illnesses, as well as be the same size or slightly bigger than the recipient. It is preferable to use donors of the same breed.


Screening tests for the donor include the following:

  1. complete blood count
  2. serum biochemistry profile
  3. urinalysis
  4. urine culture and sensitivity
  5. heartworm antigen
  6. toxoplasmosis titers (IgG and IgM)
  7. intravenous pyelogram
  8. blood type and blood cross-match compatible to the recipient

The cost of renal transplants in dogs is about $9,500-11,000, and an additional $3,000-4,000 could be added onto this price if the animal requires dialysis before the surgery. Immunosuppression drugs average from $150 for small breeds to $2,000 for large breeds a month, depending on the individual size and dose requirements of a particular patient.

The drugs commonly used for renal transplantation in dogs are cyclosporine (twice daily for life), azathioprine (every other day for lifetime), and predisolone (first 3 months only). Major complications that can occur after transplantation include acute rejection of the kidney, infections, and complications with drug therapy such as hepatotoxicity, bone marrow suppression, gastrointestinal problems, and neoplasia. The recipient is usually in the hospital for 10-14 days following transplant, and can be discharged 2 days after surgery.

 

Cardiac Therapies

Heart Valve Replacement

Heart disease is the leading cause of death among our canine friends. Veterinary cardiologist Dr. Chris Orton at Colorado State University and his team have been performing heart valve replacement surgery since 1997, proving wrong the conventional lack of confidence in valve replacement in canines. Dogs typically receive heart valves made of bovine pericardium.

Open-heart surgery for dogs requires a six- to eight-person team to carefully monitor the patient before and during the invasive surgery. The entire surgery lasts five hours, during which time the dog is connected to a blood oxygenator and the heart is bypassed. The defective valve is removed and the replacement valve is precisely sewn into place. The dog's heart is then restarted and monitored for at least two hours after the surgery is completed.

Heart replacement valves in dogs can last for the remainder of the dogs lifetime so long as clots and tissue rejection to not occur.

Cyclist Lance Armstrong's puppy, Rex, was born with a defective heart valve and underwent valve-replacement surgery to correct the defect. He is currently doing well and the valve is functioning properly.

Valve replacement in dogs is expensive and requires excellent renal and other systemic health in the dog. For these reasons, valve replacement surgery in dogs is not a common procedure.

Pacemakers

Pacemakers in dogs are used to treat the same bradycardic and tachycardic symptoms as in humans caused by blockage of the heart. The first pacemaker surgery on a dog was performed in 1968, less than a decade after the first human pacemaker implantation. About 300 pacemakers are implanted in dogs each year, many of which have been willed to dog recipients by the deceased. There are about 4000 dogs who need pacemakers each year, but only 1 in 10 of these dogs will get one.

This ECG shows the irregular rhythm of a ten-year-old American cocker spaniel's heart. This dog has trouble standing and loses her footing when she walks. The period of irregularity can be easily corrected with a pacemaker implant.

There are no pacemakers made specifically for use in dogs, but human pacemaker users are often outlasted by their pacemakers, leaving behind a functioning pacemaker with less battery power left than a new pacemaker. Some people with pacemakers choose to donate their pacemaker for veterinary use after death. Pacemakers tend to last up to 10 years but a dog would greatly benefit from even 5 years of use. A dog with a pacemaker implant will generally live 3 to 5 years longer than without the device.

One difficulty in implanting used pacemakers is the removal from the deceased human. The pacemaker leads often experience accumulation of surrounding heart muscle tissue and become difficult to remove after death. Because of such difficulty, many leads are simply cut in order to remove the pacemaker, rendering the donation useless.

Pacemakers for implantation.

Another method that pacemakers are obtained for implantation in dogs is through manufacturing supply houses. If a pacemaker has not been used by a human and has been ‘on the shelf' for too long, it will not be suitable for use in a human, but a dog could still benefit from this ‘expired' pacemaker. Thus, many veterinary hospitals request donations from these supply houses of their pacemakers that will go unused if not for dogs.

 

To implant the pacemaker, the lead is snaked through the jugular vein in the dog's neck and threaded until it enters the heart. It is attached within the heard and the pulse generator is placed under the skin at the back of the dog's neck. It generally requires only one day in the hospital.

X-ray image of an implanted pacemaker in a dog.

The operation costs $2000, and because most devices are donations, this fee does not include the cost of the pacemaker. The best candidates for pacemakers are older and have malfunctioning hearts but are otherwise healthy dogs. These operations are not performed on dogs with other illnesses that could shorten the dog's life. Once the pacemaker is implanted and the incision is healed, the dog is able to resume normal activity with stable heart function.

After pacemaker implantation, the heart rhythm is restored to normal and the dog is able to function without trouble.

 

Orthopedic Therapies

Just like humans, dog hips wear out over time. The two main joint diseases that dogs develop are osteoarthritis and dysplasia in the hips. These are mainly a product of wear and tear on the cartilage of the hind-leg joints.

These joint diseases can cause severe pain and difficulty with movement for the affected dogs. But because man's best friend may be completely healthy aside from his hip pain, total hip replacement (THR) is a solution that can add quality years of movement to a dog's life. THR has been performed in dogs since 1974, and costs between $3,600 and $3,800 per hip. A good candidate for THR must be at least 9-12 months old to be sure he has finished developing, and weigh at least 30 lbs. Four out of 5 dogs with hip disease can return to full normal function with the replacement of just one of their hips.

Dr. Ronald Fallon was one of the first veterinary orthopedic doctors to develop THR in dogs and practiced at Ohio State University , where he and fellow surgeons have performed 2,500 dog THR surgeries to date.

Ron Fallon, DVM, General and Orthopedic Surgery

The hip implant for dogs is similar to its human counterpart, but it is much smaller in dimension. X-rays are used to determine the dimensions of an appropriately-sized implant. The implant consists of a femoral stem, a ball-shaped head, and an acetabular cup, just like human implants. The stem may be cemented or press-fit, and the operation mirrors the operation in humans, but takes only 90-120 minutes to complete.

The femoral stem is usually made of cobalt chrome or stainless steel, while the cup is made of ultra high molecular weight (UHMW) polyethylene. PMMA is the cement used with cemented implants, whereas 250-micron (diameter) titanium beads usually cover the stem surface of the press-fit implants.

Once implanted, the THR requires 1-2 months to heal. The dog is limited to walking only during this period, but once the implant site has healed, 95% of patients are able to continue normal and pain-free activities with full range of motion as a healthy joint.

A cemented implanted THR..

Patients and owners of dogs who undergo THR are generally quite satisfied with the procedure, as it provides a marked improvement in the dog's quality of life.

The THR is expected to last 10-15 years, which usually surpasses the remaining lifetime of the dog. In less than 5% of cases, the THR will malfunction through loosening of the acetabular cup or femoral fracture. However rare these failures are, they must be corrected immediately with revision surgery.

 

Pre-THR function of hip.

Post-THR function of hip.

Prosthetic Limbs

When a dog gets into an accident, it is likely for them to lose a limb or be even to sleep if the injury is bad enough. Amputation of the injured limb is usually the only way to save a dog with a severe leg injury. Congenital defects can also result in a shortened and partially missing leg. When this happens, the dog's mobility is severely compromised and a prosthetic device to replace the missing portion is the only way to return mobility to the injured dog.

A suitable candidate for a prosthetic limb must have a ‘good stump' remaining where the amputation or injury took place. A clean and level stump is required for good attachment of the artificial limb and a reasonable length should remain to support the weight when the prosthesis is attached. For dogs that have been in accidents, a good stump will allow a prosthesist to use the best prosthetic device available.

There is no standard means by which dog leg prosthesis are fashioned, but the device continues to evolve. The two main types of prostheses are attached with a harness or with a Velcro type material. Many prostheses for dogs are crafted by companies that make artificial limbs for humans, but pet prostheses have advanced most in the past 25 years. Most procedures are done as favors by orthopedists who have concern for the animals and have skill in designing appropriate prostheses.

The design of the prostheses varies greatly depending on the type of injury the dog has sustained and how much of the limb is missing. When professionally designed, the dog's remaining leg is cast and a mold is made for the connection area of the prosthetic limb. The cost of the limb varies greatly depending on the number of joints needed and the material used to construct the artificial limb, but the price is generally around $800.

Here are several cases in which an amputee was restored mobility with prosthetic attachments.

Kuma

When an Akita husky, Kuma, was hit by a cement truck, her right hind leg was amputated. Kuma's owner, John Weaver, had the idea to fashion a prosthetic limb for her out of a plastic antifreeze bottle, a table leg, and a rubber stopper. Since then, Weaver has designed a more advanced prosthesis of titanium and aluminum with a shock absorber.

Triumph

Several others have joined those like Weaver in developing limb prostheses for animals. When Triumph, a Siberian Husky, was found with both of her hind legs cut off, Tom Brady of Total Orthotic and Prosthetic Systems designed artificial limbs to help her walk again. Tom has designed a type of prosthetic leg that is attached to the stump with suction rather than belts and laces as fasteners.

Sassie

Sassie was born without a portion of her lower hind leg. Her owner, Dr. Beth Bishop, originally handcrafted a prosthetic limb out of laced leather, an inner sole of a shoe, and duct tape. Eventually, Bishop contacted a Colorado animal prosthesis company, Horton's Orthotic Lab Inc., and Sassie got measured for a limb made of hard plastic and foam.

Sassie with her prosthesis of plastic and foam.

 

 

Peg

Peg was born without an ankle or paw on her front right leg. Dr. Miller of Greater Flint Prosthetic Center volunteered to create a limb for Peg that would aide in her mobility. To prevent peg from chewing on the leg, Miller constructed it out of a Kevlar-like material.

Peg is measured for her artificial limb attachment.

Depending on the material, a prosthetic limb could last for the remainder of the dog's life. Plastic and carbon fiber prostheses will not change shape over the lifetime of the dog, while neoprene wrap supports tend to last only 12-36 months.

Reggie

Reggie was shot in the paw and developed an infection that necessitated amputation of his leg. This prosthesis does not have a knee so Reggie only uses it when he is very active.

Reggie with his shock absorbing ‘foot' on a hind leg prosthesis.

 

Recently, companies have been established that specialize in pet orthotics and prosthetics. OrthoPets is one such company that provides custom fabricated devices for pets. Although pet prosthesis is not a major area of veterinary medicine, it is a measure that can be taken when euthanasia may be the only other option for severely injured dogs, when their mobility is severely compromised such that they cannot function properly. An artificial limb restores close-to natural movement for many dog amputees.

 

Blood Transfusion

When dogs suffer from traumatic injuries or invasive surgical procedures, they require transfused blood to replace that which is lost. Transfusions are also necessary in other critical situations, including toxicity and anemia in canines.

Dog-blood transfusions are governed by the same principles as blood transfusions in humans. The donor and recipient must be of compatible blood types, of which dogs have eleven. Dogs, unlike humans, are born without antibodies in their blood. For this reason, first time transfusions will not have a reaction, but further transfusions will cause severe reactions if the dog has a mismatch in the DEA1.1 blood type. Because the immune systems of dogs are so fierce, cross-match tests must be performed upon each dog blood transfusion. Only about one in every 15 dogs is negative for all antigens and thus, a universal donor.

Because veterinary surgery is advancing rapidly, a need for dog blood donors has arisen. Many veterinary hospitals have blood donor programs that hold periodic blood drives.

In different critical situations, a dog may need different blood component donations. RBCs are given to an anemic dog while plasma may be transfused when additional blood volume is needed.

Blood donors must meet specific requirements in order to qualify to donate. They must weigh at least 50lbs, have high enough blood component values, and have no infectious diseases. Universal donors are often sought and blood banks request donations from these dogs every three months. Dogs must wait at least two to three months between donations, but in emergency situations, a dog may donate again after just one month. After donation, fluid is administered intravenously to replace the volume lost upon donation.

When blood is collected, it is separated into its components and stored in the refrigerator (for RBCs) and freezer (for plasma). Whole blood may be used immediately and without separation if it is urgently needed. An average donation consists of 4 units or bags of blood. It takes only 5-15 minutes for the donation.

Upon arrival to the blood bank, a hematocrit test in performed. A small area of fur is cut from the dog's neck and blood is drawn and collected while the owner waits.

 

Plasma press-separation technique.

One donation has the potential to save two dogs in need of transfusion.

Because there is a shortage of banked dog blood, most blood banks offer free transfusions for donor dogs if they ever need them as incentive and reward for their donation. The dogs are also usually allowed to choose a chew toy and they get other little thank you gifts including bandanas and acknowledgement dog tags, or medical rewards including heart-worm medication and vaccinations.

 

Other Therapies

Blood Donation Alternative

Oxyglobin is an approved drug that is used in dogs when a blood transfusion is not available. It is chemically stabilized hemoglobin in a saline solution that will not react with blood antigens because it carries no antibodies. This treatment is administered in situations that require increased oxygen delivery to the dog's tissues before a transfusion is available or before the dog can make new blood cells on its own.