January 6, 2012 10:37
An 11-year-old Arab mare defies the odds and survives more than 12 hours in surgery to remove one side of her jaw along with a grapefruit-sized, cancerous tumour.
When Dr. James Carmalt examined the grey Arabian mare named Noor for the first time at the WCVM’s Veterinary Medical Centre last fall, the first thing that surprised him about the horse was her body condition.
“You could tell that Mr. Abidi (her caregiver) had been working hard to ensure that she had the right type of feed available and had managed to keep her weight on,” explains Carmalt, an equine surgeon at the WCVM. “She looked like a relatively normal horse — other than having this huge growth on the side of her face.”
The grapefruit-sized growth, about 26 centimetres (cm) in width and 20 cm in height, had been developing on the back curve of the horse’s right jaw ever since an accident occurred when she was two or three years old. Earlier in 2010, Syed Abidi found the disfigured mare on a farm in B.C. while searching for a specialized bloodline of Arab breeding stock.
He knew time was running out for the tough little horse that had managed to adapt and survive for so many years: “I saw a horse that needed help and I went for it,” says Abidi.
With the owners’ consent, Abidi brought the horse to Dr. Ryan Shoemaker of Delaney Veterinary Services in Sherwood Park, Alta. But after the cancer diagnosis was confirmed, Shoemaker referred the case to Carmalt.
“I think Dr. Shoemaker knows that if I could concentrate on equine head and teeth cases for the rest of my career, I would be a very happy man,” jokes Carmalt. “But he also knows that we’ve got many willing hands to help with post-operative care — something that’s very difficult to manage in private practice.”
“She wanted to go for it”
After several phone and email discussions, Abidi and Noor met Carmalt for the first time in November 2010. For two days, Noor underwent a battery of tests at the WCVM: a physical examination, a full mouth oral examination, an endoscopy of her upper airway and both of her guttural pouches, and radiographs of her skull and chest.
“Everything culminated with the CT scans. That allowed us to do a 3-D reconstruction of the tumour and that’s when we found out how large and invasive it really was,” explains Carmalt, adding that the tests showed no metastasis in the horse’s lungs.
Then Noor went home for three weeks — giving Abidi time to consider the risks and expense of the experimental procedure. “We talked at length about the risks. We also made a lot of effort to discuss the potential endpoints beforehand because we all wanted to consider the horse’s welfare,” says Carmalt.
“If she reached endpoint X or she suddenly decided that she had enough, we agreed that I would be the ultimate decision maker about euthanasia.”
“Dr. Carmalt and I — we think alike. We’re cautiously optimistic. We understand the risks involved but we’re willing to continue moving forward,” adds Abidi. “More than a dozen times, I was told to just put her down because it was too risky and too much money. But Noor is a smart horse — she let me know that she wanted to go for it.”
In the meantime, Carmalt prepared for a surgery that, based on veterinary literature, had never been done before. Besides experimenting on equine cadavers, Carmalt consulted with colleagues in the U.S. “Almost universally, the answer was, ‘Good luck with that,’” says Carmalt, who found invaluable advice closer to home.
Dr. Kathleen Linn is one of the WCVM’s small animal surgical specialists and routinely removes parts of the jaw in dogs diagnosed with cancer. But the surgeons had to plan for a different scenario with Noor. Instead of performing most of the surgery inside the mouth (the practice used for canine patients), the surgical team — consisting of Carmalt, Linn and Drs. Imma Roquet and Holly Sparks — would need to do most of the procedure from the outside because of the tight space inside the horse’s mouth.
“Like digging out a fossil”
Once Noor was prepped for surgery, the team inserted a tube through a tracheotomy in her neck. As well, they isolated her carotid artery in case a large bleed occurred and they needed to block the artery — an emergency procedure that slows down blood loss and buys time for surgeons.
The team used that emergency option four times during Noor’s marathon surgery that lasted for more than 12 hours. The procedure began with a 30 cm incision just below the tempomandibular joint (TMJ), curving around the bottom of the jaw to the front. The surgeons dissected their way down to the bone, lifting the tenuous tissues and facial nerves up like a flap until they could see the bone.
“Then we made a horizontal cut just below the TMJ at the top and a vertical cut between the second and third cheek tooth and lifted out the jaw,” describes Carmalt. “And that left us with a massive hole.”
The actual removal of the jaw bone took less than 15 minutes. What took time was cutting through the complex web of blood vessels — a process that Carmalt compares to digging out a fossil with painstaking care. “With a tumour, there’s a massive amount of new blood vessels. We knew where the major blood vessels were but there were so many vessels involved in the tumour — it was a whole entity on its own.”
After removing Noor’s swollen lymph nodes and any cancerous tissue, the surgical team began the laborious process of closing the hole with five layers of tissue and skin. Two catheters were left in the hole: one suctioned fluid out of the closed area while the other was a “soaker” catheter that allowed clinicians to put painkilling drugs directly into the wound.
As expected, Noor was wobbly in the recovery room but showed no ill effects of being under general anesthesia for so long. Within six hours, her post-surgery care team was offering her a variety of feed to choose from.
Horizontal to vertical chewing
When surgeons remove one side of a dog’s jaw, the animal can still chew its food up and down on the opposite side of its mouth. “But horses chew their feed horizontally so they need both sides to chew,” explains Carmalt. “We had no idea what Noor was going to do, but in retrospect, I should have held more stock in my physical exam and the CT findings.”
What the CT scan had shown was that Noor’s cheek tooth angles were flat as opposed to 15 degrees — the normal angle found in horses. Carmalt and his team eventually realized that Noor had already adapted to her disability before the surgery, learning how to chew vertically.
Three days after the procedure, Noor was eating enough to maintain her body weight. The rest of her three-week stay went relatively smoothly — thanks to the hard work of veterinary students who cared for Noor around the clock.
Noor returned home to Alberta just before Christmas. Since then, her recovery has had its challenges especially because of the harsh winter conditions on the Prairies. Noor also had some trouble eating because of dental issues, requiring Abidi to try different feeding options for her.
But the fact that Noor is alive and now has the chance to live a relatively normal life is still a miracle to Abidi who credits Carmalt for taking the chance on Noor. While he acknowledges that it was costly to save Noor, Abidi points out that he also spent the money to give the WCVM surgical team a chance.
“Dr. Carmalt told me it was a great learning experience for everyone involved. And by talking about this surgery, maybe others will read about it and be more confident about taking on these kinds of challenging cases in the future.”
For veterinary students, Carmalt says Noor’s case emphasizes the importance of referring cases to teaching centres like the WCVM once they’re in practice. It has also led to some intensive discussions about medical ethics at the veterinary college.
“From an ethical standpoint, I think we were very close to the edge with this horse. And if she hadn’t recovered as quickly as she did, we may have wished we hadn’t done it,” admits Carmalt. “I think as long as you have the welfare of the horse absolutely paramount and you aren’t swayed by the financial and emotional investments of the client, then I think you can try. You just need to know when to stop.”
Besides Noor’s strong will to survive and adapt, the other factor in the mare’s favour was Abidi: “He had already put in a massive amount of work to care for Noor plus he was willing to invest thousands of dollars in her surgery. After all that, I knew he wasn’t going to back off on his care,” says Carmalt. “He was in it for the long haul.”
Reprinted with permission from Horse Health Lines, publication for the Western College of Veterinary Medicine’s Equine Health Research Fund. Visit www.ehrf.usask.ca to sign up for our e-newsletter.
September 20, 2011 10:40
Equine infectious anemia (EIA), also commonly referred to as swamp fever or Coggins disease, is a viral disease of horses and other equidae that affects the immune system. It is transmitted by blood, mainly via blood-sucking insects, and by needles contaminated with blood containing the virus, or through breeding. The EIA virus can only reproduce in living cells, and in this way spreads throughout the animal. All infected horses carry the virus for life. The fact that the virus lives within the cell is the reason treatment and vaccination are ineffective.
In general, there are three forms of EIA in which the virus can be detected by the presence of antibodies produced by the horse in response to the EIA infection. In EIA's acute form, the virus actively multiplies and attacks the immune system and other body organs. Some of these horses may die suddenly, others may appear constantly and severely ill and harbor heavy concentrations of the virus in their blood. Horses afflicted by the chronic form of the disease may also contain high concentrations of the virus, but they tend to alternate between periods of appearing healthy and the disease state seen in the acute form. Some of these animals will debilitate over time, and present poor body condition. Acute and chronically infected horses always pose a high risk of infection to EIA-free horses because they have a high concentration of virus in their blood. The third form of EIA involves unapparent carriers. These are seemingly healthy horses that also carry the virus, but in a low or undetectable concentration in the blood. Inapparent carriers may never become acute or infectious; however, stress and other diseases or treatments can activate the acute form resulting in a high concentration of virus in the bloodstream. This third form of the disease is often the source of debate about the meaning of the Coggins test and the fate of the unapparent carriers among horse owners who are not well-informed about the disease.
The clinical symptoms of EIA depend on the severity of infection and vary from horse to horse. They can include one or more of the following: fever, depression, decreased appetite, fatigue or reduced stamina, rapid breathing, sweating, weight loss, bloody or watery eye discharge, swelling of legs, lower chest and abdomen, general weakness, wobbly gait, pale or yellowish mucous membranes, signs of abdominal pain, and abortion in pregnant mares.
The origin and evolution of the EIA control program
EIA has been recognized in Canada since 1881, originally as swamp fever. Initial efforts to control this disease based on the elimination of clinically ill horses were largely unsuccessful because infected but unapparent carriers perpetuated the disease within the horse population and served as a continuous source of infection for disease-free horses. In 1970, Dr. Leroy Coggins developed a diagnostic test for EIA using an agar-gel immunodiffusion (AGID) reaction. The Coggins' test is consistently reliable in detecting the presence of antibodies regardless of whether the infection is acute, chronic or unapparent. The test's reliability and the identification of unapparent carriers paved the way for implementation of more successful EIA control programs.
In 1971, EIA was made a reportable disease in Canada, and the first EIA program was introduced in 1972. Agriculture Canada offered the Coggins test to Canadian horse owners and voluntary testing was performed by accredited veterinarians. The government was only involved in trace-out investigations and testing after a reactor was reported. EIA reactors were either permanently quarantined or destroyed. There was no compensation paid for any destroyed horses during the first seven years of the program, but in 1978 the federal government introduced the compensation payment of $200 to owners whose horses were euthanised. In 1989, Agriculture Canada began to accredit private laboratories to perform the Coggins test although all atypical or positive results were confirmed in a federal laboratory before any quarantine and investigation activities were implemented.
From 1972 to 1993, of the approximately 1.8 million horses tested, some 14,000 were confirmed positive for EIA. Although some owners chose permanent quarantine for their animals, the majority of horses were destroyed. During the same time period, the rate of infection among horses tested dropped from 2.9% to 0.39%, indicating that the program reduced the number of infected horses and was successful in controlling the spread of the disease in all but some remote and high risk areas.
In 1994, the government reprioritized its activities and reduced its involvement in the program by modifying the EIA control policy. EIA remained a reportable disease and testing procedures and requirements did not change; however, Agriculture Canada notified the owners and "contact animal" owners instead of investigating reactors and testing positive animals. Horses in contact with reactors were not quarantined and their testing was conducted at the owner's expense by Canadian Food Inspection Agency (CFIA)-accredited veterinarians. Owners required a federal licence to remove infected animals from a premises. At this time the government also discontinued ordering the destruction of infected horses and the payment of compensation. Between 1994 and 1998, approximately 337,000 horses were tested and close to 550 reactors were either voluntarily destroyed or permanently isolated. During that period, the rate of infection among tested horses increased from 0.39% in 1993 to 0.66% as recorded in 1999.
The current EIA control program
In April 1998, the newly created CFIA was approached by the equine industry to modify the EIA program. EIA does not pose a risk to food safety or human health; however, the CFIA agreed that unless EIA was controlled there could be devastating effects on the Canadian horse industry including those related to international trade. Consequently the CFIA agreed to participate in the control of EIA providing the new program was industry-driven and self-funded.
This current program consists of two components. Under the first component, horse owners voluntarily pay to have their horses tested when they are identified by the industry (i.e. movement into shows, point of sale, etc.). Testing is conducted by private veterinary practitioners and EIA private laboratories accredited by CFIA for that function. The second component of the program is the mandatory response, for which the CFIA is responsible. Each time an EIA positive horse is discovered, it must be reported to the CFIA and disease control measures are implemented. The premises on which a reactor is discovered is declared an infected place and all susceptible animals must test negative to be allowed to move off the property. Horses in contact with the reactor within 30 days of the sampling date are also tested. All EIA test-positive horses are retested and reactors with clinical signs are ordered destroyed. Owners of horses that are confirmed positive for EIA without clinical signs must choose whether to either keep the horse in a permanent quarantine or have it destroyed. In the later case, the CFIA orders the horse destroyed and pays compensation. The government's part of the program is delivered at no charge to owners.
When the program was introduced in 1998, the maximum amounts payable were set at $500 and $1000 for grade and pure-bred horses respectively. To further promote the program and encourage testing, compensation has increased to a maximum amount payable of $2000 per horse.
Accredited laboratories charge owners $2 for each animal tested to offset the cost of the CFIA's mandatory response. While this amount may, in some years, cover the cost of compensation, it does not cover CFIA's cost in terms of manpower and operating cost. This is provided as a service to the industry.
The CFIA's position on EIA control program
The CFIA has not imposed the EIA program on horse owners, but has responded to a request from the industry to administer a program that the majority of horse owners support. Participation in the program is voluntary and all elements of the program have been developed in conjunction with the industry. The program is based on internationally recognized disease control standards, current knowledge of the disease, and diagnostic methods. As there is no effective treatment for EIA and no vaccine to prevent it, the disease can be successfully controlled by testing and the elimination of reactors including unapparent ones. The Coggins test is an integral part of the CFIA control program.
EIA does not pose a food safety risk and is not a public health concern, therefore the CFIA's involvement is based on the furtherance of animal health in Canada.
for more information: www.inspection.gc.ca
August 19, 2011 07:48
Animals (particularly horses) infected with the virus show neurological disturbances. Clinical signs may include:
- ataxia (lack of coordination);
- depression or lethargy;
- head pressing or tilt;
- impaired vision;
- inability to swallow;
- loss of appetite;
- muscle weakness or twitching;
- partial paralysis;
- coma; and
The clinical signs of WNV in mammals can be confused with rabies.
Most infected domestic birds do not show signs of infection, and only domestic geese appear to be particularly susceptible to disease and/or death when infected.
WNV-infected geese will show signs of depression, loss of appetite, inability to stand, weight loss and death. The virus can be difficult to distinguish from Newcastle Disease and Avian Influenza in domestic birds.
March 2, 2011 21:30
Western Canada’s most common (and not so common) skin conditions.
Dr. Sue Ashburner still shudders when she describes the sight of one of her equine patients covered with thousands of bloodsucking ticks last winter. “We occasionally see wood ticks on horses during May and June, but I didn’t know what kind of ticks would be on horses in February,” admits Ashburner, a veterinary clinician at WCVM’s Large Animal Clinic in Saskatoon, Sask. Dr. Lydden Polley, a parasitologist at the College, soon solved the mystery: he identified the parasites as Dermacentor albipictus (Acari: Ixodidae), more commonly known as moose ticks. “It was the first time I ever saw a horse in this area covered in moose ticks,” says Ashburner. “That’s what I like about working on dermatology cases. There are always new things, and those cases challenge you to find out what you’re dealing with. Sometimes we never know the cause, but we usually know how to treat what we see.” At least once a week, Ashburner gets a chance to use her dermatological know-how on equine patients living around Saskatoon — an area that’s populated with horses of all breeds and disciplines. The clinic’s number of dermatology cases usually rises in the spring after horses shed their coats and owners suddenly notice lumps, bumps, growths or parasites that have shown up during the winter. Thanks to advances in diagnosing and treating equine skin conditions, veterinarians can offer clients more effective therapies and more understanding of what causes skin problems to develop. Most clients call for advice or to arrange for a veterinary visit, but some still insist on using their own home remedies that often makes Ashburner’s job tougher. “After they’ve scraped it, treated it or used ointments that burn the skin, it doesn’t look anything like it originally did. These remedies usually just make things worse.” While Ashburner isn’t expecting another moose tick infestation case soon, here are some common skin conditions that she and veterinary pathologist Dr. Ted Clark regularly see out in the field and in the pathology laboratory. Their comments accompany some additional information gleaned from the text, Equine Dermatology, co-authored by Drs. Danny Scott and William Miller Jr. • Dermatophytosis or ringworm is a fungal infection that’s transmitted by contact with infected hair, bedding, tack and grooming equipment. Ashburner often diagnoses multiple cases of ringworm in young horses living in close quarters throughout the winter months: the infection often goes unnoticed until horses shed their winter coats. The most consistent clinical sign is one or many circular patches of alopecia (hair loss) with variable scaling and crusting. But horses may also develop the classic ring lesion with a healed centre and fine follicular papules and crusts on the ring’s edges. Lesions are usually multiple, and they’re most commonly found on the face, neck, the sides and girth. The lesions usually go away within three months, but veterinarians often use topical and systemic treatments to help their patients’ response to the infection, to reduce the spread of the fungus and to speed up the healing process. • Sarcoids are the most common skin tumour of horses around the world. Veterinary researchers believe the cause of sarcoids is viral, and research has shown that bovine papillomaviruses (BVP) are commonly involved in sarcoid development. Lesions frequently show up in areas of a horse’s body after a wound or trauma, or they may also spread to other areas of the same horse or to other horses through biting, rubbing, tack, equipment and insects. Sarcoids occur anywhere on a horse’s body, but most lesions are found on the head, neck and ventral body surface. The lesions’ appearance can be verrucous (wart-like), fibroblastic (proud flesh-like), mixed verrucous and fibroblastic, and occult (flat). Sarcoids do not metastasize, and some tumours may disappear after several years. Depending on available resources, veterinarians can choose from surgical excision, cryosurgery, radio-frequency hyperthermia, laser therapy, radiotherapy, chemotherapy, immunotherapy or combinations of treatments. • Papillomas present in two different forms: as warts (viral papillomatosis) or as aural plaque (ear papillomas). Viral papillomas spread through direct contact or indirectly through contact with contaminated equipment or housing. Young horses often develop clusters of warts, usually on their muzzles or lips. “They bother the owner much more than horses,” says Ashburner. “If left alone, they tend to go away and you can’t rush them. People always buys potions and lotions, but they usually make no difference.” Aural plaques — white-greyish crusts commonly found in horses’ inner ears — don’t respond very well to topical treatments, and they rarely go away. Fortunately, these lesions are only a cosmetic problem. • Eosinophilic granuloma or nodular necrobiosis is an equine dermatosis most commonly seen in the spring and summer. These nodules are round, elevated, and occur as single or multiple lesions on the back, withers and neck. The lesions aren’t painful or itchy, and the overlying skin and hair coat are normal. Veterinarians can surgically remove one or several lesions, or treat multiple lesions with systemic glucocorticoids over several weeks. Some lesions undergo spontaneous remission in three to six months, while older or larger lesions must be surgically removed. • Allergic reactions show up as anything from bumps and wheals in all shapes and patterns to angioedema (swelling) involving the muzzle, eyelids, under the belly, legs or the entire body. These reactions result from insect bites, plants, drugs or vaccines, a change in feed, bedding or the horse’s environment. Gathering a thorough medical history is how veterinarians usually track down the source, says Ashburner. “It could be caused by a minor environmental change, a sudden hatch of bugs in the area. It really pays off to ask a lot of questions.” Ashburner and her colleagues usually try to eliminate the source of hypersensitivity or generally treat the horse to try and decrease its immune response. “One treatment that has worked quite well is to feed the horse raw linseed oil: its Omega 3 fatty acids help to decrease the animal’s hypersensitive response in the skin. That seems to calm things down and it helps to make the other treatments work better.” • Scratches or pastern dermatitis most commonly affects one or both hind limbs with varying levels of pain and itchiness. The condition initially shows up as erythema (dew poisoning), swelling and scaling on the pastern, then progresses to discharge, matting of hair and crusting. Veterinarians usually diagnose this problem when there’s abrasive mud in corrals, or when ice crystals are mixed in the snow and dirt. “We think the moisture content has something to do with it: something seems to set up the right environmental conditions to induce scratches, particularly in the spring,” says Ashburner, adding that the condition usually shows up on a white leg. “It responds very well if treated early, but it’s often missed by the owners until the horse’s pastern is very sore or very swollen. And the longer they have it, the harder it is to treat.” Severe cases of scratches can also lead to a longstanding, immune-mediated infection called vasculitis that can take months to cure. If diagnosed early, the ideal treatment is to clean the area very well with mild soap (no abrasive cleaners) then remove as much of the scabby debris as possible. Clipping the hair can help to remove the scabs. “We keep the area dry and use a topical cream — a combination of antibiotic and steroid cream — to fight the mixed infection,” explains Ashburner. Clark adds that it’s important for veterinarians to be aware that scratches isn’t “one specific disease with one specific cause.” If certain horses or horse herds continue to be plagued by this type of dermatitis, practitioners need to look at the animals’ environment, their habits and what they’re used for to learn more about probable causes. • Rain scald (dermatophilosis) is a bacterial skin infection that causes superficial, pustular and crusting dermatitis in horses. These lesions are most commonly found on horses’ rumps, saddle area, face and neck — or on pasterns, coronets and heels (in the form of scratches). The two most important factors that lead to rain scald are skin damage and moisture. The condition is often diagnosed in horses after intense rain, and when temperatures and humidity are high. Veterinarians on the Prairies don’t often see rain rot, but it’s a common problem in B.C. While most cases of rain rot go away within a month, the best treatments include keeping the animal dry, removing crusts, and using topical treatments and using systemic therapy if the infection is chronic or severe. • Melanomas are malignant skin tumours that are most commonly — but not exclusively — found in grey or white horses over six years of age. Arabians, Percherons and Lippizaners commonly develop these tumours that are often found on the undersurface of the tail and the perianal region. Tumours can also be found on the lips, base of the ear, on the legs, or anywhere else on the horse’s body. The melanomas are usually firm, nodular to plaque-like, and they may or may not be alopecic (hair loss), hyperpigmented or ulcerated. Veterinarians can use surgical excision or cryotherapy to remove solitary tumours, but in most cases, the tumours require no treatment. • Insect hypersensitivity: Western Canadian horse owners and veterinarians deal with fewer parasitic problems than in other parts of the world because of the region’s cooler climate, but insect hypersensitivity is still a common problem in the spring and summer months. Controlling insects and using anti-itching agents can help to manage insect hypersensitivity. The use of ivermectin, moxidectin and other dewormers has also helped to reduce the occurrence of conditions like sweet itch, says Ashburner. - Sweet itch or Summer Seasonal Recurrent Dermatitis (SSRD): The most important cause of equine insect hypersensitivity is Culicoides gnats (sandflies, no-see-ums, biting midges). Affected horses develop itchy, crusted papules on the top of their tails, along their mane, neck, withers, hips, ears and forehead. The disease’s itchy nature causes horses to scratch and chew at themselves, or they may rub against stalls or fences. That can lead to hair loss, ulcer development and damage to the animals’ manes and tails. - Mange is caused by mite infestations in horses’ coats. Owners and veterinarians usually see these infestations during the late winter and early spring, and contributing factors include crowding, prolonged stabling, and poor nutrition. - Lice infestations are commonly found in horses during the winter when the animals’ coats are longer and they may be in close contact with their herd mates. Biting lice are usually found on the horses’ dorsolateral trunk, while sucking lice prefer the animals’ mane, tail and fetlocks. Clinical signs include scaling, a dishevelled coat, hair loss and mild to moderate itchiness. Reprinted with permission of Horse Health Lines, news publication for the Western College of Veterinary Medicine's Equine Health Research Fund. Sign up for the Horse Health Lines e-newsletter at www.ehrf.usask.ca