Hip Dysplasia in Pregnant Dogs

Written for my Animal Reproduction class. Concerns physiological description of hip dysplasia occurring in a pregnant bitch.

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Hip Dysplasia in Pregnant Dogs and Puppies

Rachel M. Counts

 

Hip dysplasia is a prevalent problem in large canine breeds, and is influenced by genetic and environmental factors. It concerns the abnormal development of the acetabulum and coxofemoral joint, where the femur head meets the pelvis. The major abnormalities occur between the muscles surrounding or on the hip joint, and the development of bone at the hip joint. Rubbing of bone, or joint laxity occurs in the dog and causes the dog to be unstable and experience pain or stiffness in the hind legs.

Hip dysplasia is detected using radiographic techniques, and it measured by evaluating nine different areas of the hip joint. The craniolateral acetubular rim, caudal acetubular rim, fovea capitus, and other important points on the hip are observed for abnormalities to grade the canine on hip dysplasia and the degree of it. (Orthopedic Foundation for Animals, 2010)

Certain treatments are available to help alleviate any pain or discomfort the dog may feel. Surgical treatment is an option, but in this case we will be observing a dog with only moderate hip dysplasia that is pregnant.

Anti-inflammatory drugs are some of the most common drugs given to dogs with hip dysplasia, but other drugs meant to control pain, encourage cartilage repair, increase mobility and slow down the breakdown of bone in the joints are also administered. These common drugs include aspirin, carprofen etodolac, cosequin®, glycol-flex®, and adequan®. (Plotnick, 1999) However safe use in pregnant dogs has not yet been established for the medicines carprofen, etodolac, cosequin®, glycol-flex® and adequan®. (Rimadyl, 2011) (Zoologist, 2010) (VetRxDirect, 2011) (1-800-PetMeds, 2011) (Adequan Canine, 2005) Aspirin is known to cause birth defects. So drug control is not an option for pregnant dogs with hip dysplasia. (Randall, 2011)

Other treatments the can help reduce the symptoms of hip dysplasia include a strict diet to prevent weight gain or to promote weight loss, reduction of exercise on hard surfaces, physical therapy to tone muscles (such as underwater therapy), and optionally joint fluid modifiers. (Kahn, Line, & Merck & Co., 2010)

Our pregnant dog we are observing has recently copulated. Higher estrogen levels will help promote stronger bone health to aid in carry her new puppies, but eventually the added weight will stress her hips to a point where she may be completely immobile, and in great pain due to the lack of medications she can take.

However, the higher estrogen may account for the new puppies bone developing. (Steinetz, Williams, Lust, Schwabe, Büllesbach, & Goldsmith, 2008) During pregnancy and the lactation period afterwards can account for up to 5% bone mass loss. (Karlsson, Ahlborg, & Karlsson, 2005)Calcium demand raises because of the change in nutrient needs, the change of weight, the level of activity the pregnant dog will incur, and the hormone levels will be fluxing which may change the bone metabolism. During lactation calcium can be detected in the mother dog’s milk.

“Plasma 1,25 (OH)(2) D(3) levels increase two-fold early in pregnancy due to high placental 1-alpha-hydroxilase activity, remain high until delivery and decline to normal values during lactation. Estrogen, prolactin and placental lactogen, which are involved in calcium absorption, increase at the same time. Normal or even low levels of parathyroid hormone (PTH) can be detected during pregnancy. This suggests that their physiological actions could be mimicked by the parathyroid- related-peptide (PTHrP), which increases in late stages of pregnancy and remain high during delivery and lactation. Calcitonin levels increase during pregnancy, decline during lactation and return to normal values after lactation  is stopped. The physiological roll of tumor necrosis factor, interleukin 6 and osteoprotegerin has not been elucidated yet. The above mentioned changes can exceptionally lead to generalized or regional osteoporosis.”  (Hakim & Zanchetta, 2005)

Normally the bone mass will recover after weaning, but in the case of hip dysplasia the damage done during the pregnancy could permanently infirm the dog.

The mother dog also presents the possibility of passing on the genetic traits that causes hip dysplasia. The tendency for this abnormal bone development affects both male and female canines equally. (Root Kustritz, 2007)Closely linked to hip dysplasia is osteoarthritis. “Two adjacent genes on the 12q chromosome, the alpha 1 chain of Type II collagen, and the vitamin D receptor, have been considered potentially related to the pathophysiology of osteoarthritis. … Significant results were found by assessing the two groups of diseases that led to hip arthroplasty, suggesting a possible link between some haplotypes and the risk of severe osteoarthritis in patients with hip dysplasia.” (Granchi, Stea, Sudanese, Toni, Baldii, & Giunti, 2002)

The puppies, if they do develop hip dysplasia, will not show signs of it until they are five to eight months old, but often once bone development settles and the joint becomes stable pain will be reduced by twelve to fourteen months old. (Lane & Ewart, 1996) It is also possible that relaxin and estrogens in the mother’s milk may have a possible link with hip joint laxity in puppies. (Steinetz, Williams, Lust, Schwabe, Büllesbach, & Goldsmith, 2008)

In a case study, “High concentrations of estrogens and relaxin were found in milk of HD+ and HD– bitches throughout lactation. Serum concentrations of milk-derived relaxin and total estrogens were similar in all pups, but estradiol-17B was detected only in pups of HD+ bitches. Hip joint laxity was reduced in pups that received CGS 16,949A. Hip joint laxity was increased in pups of HD– bitches that received estradiol cypionate and relaxin.” This case shows that hip dysplasia might be controlled or even prevented by using an antihormone treatment. This will inhibit the estradiol-17B and help reduce the onset of hip dysplasia in the newborn puppies. (Steinetz, Williams, Lust, Schwabe, Büllesbach, & Goldsmith, 2008)

The mother dog, who had moderate hip dysplasia, will suffer from the added weight on her hips due to the unborn puppies. This can be extremely debilitating to her condition and can wear away at the acetabulum wall, or the added weight could push the femur head out of the socket, causing permanent damage and complete loss of hind leg functions.

Birthing is also strenuous on the hips, and can cause similar damage to the coxofemoral joint. The articular cartilage is already of poor quality due to the hip dysplasia. Because its elasticity and thickness has been compromised, the heavy load of carrying and birthing puppies cannot be absorbed when the mother dog moves. Debris from enzymes released when the cartilage is damaged can get within the joint fluid and can damage or destroy the glycosaminoglycan and hyaluronate molecules. This prevents the cartilage from ever repairing.

Between the weight and cartilage loss, the synovial fluid in the joints will touch nerve endings in the subchondral bone. The immense pain suffered by the mother dog can be debilitating on its own. The body will attempt to repair itself with new bone, which will cause a decrease in the range of motion the dog can have. Osteoarthritis can occur down the line because of the stress induced by bearing puppies by the mother dog. (Othopedic Foundation for Animals, 2010)

The puppies, which now carry the risk of hip dysplasia, can experience an increased incidence of this abnormal bone development if they undergo a gonadectomy prior to five months of age. The link between CCL rupture and the hormonal effect it has on joint stability seems to be positive, but is still under research. (Root Kustritz, 2007)

Our mother dog, who suffered moderate hip dysplasia, could not take any medications during her pregnancy due to the risk involved with her puppies’ development. During the pregnancy she had a deficiency in calcium to make up the formation of her new puppies’ skeletons, and suffered bone loss. The fetuses grew and the added weight caused additional stress on her hips, causing cartilage breakdown, her femur head to pop from its socket, and possibly osteoarthritis. During birth her hips suffered tremendous strain, and permanent damage may have been incurred. She loss more calcium during lactation, and passed on the genetic predisposition for hip dysplasia to her puppies. The puppies will not show clinical symptoms of hip dysplasia until after a year of age, but may have an increased risk when spayed or neutered before five months old. The mother may have lost complete use of her hind legs, or severe damage.

Overall it is not recommended to allow a dog with hip dysplasia to breed.

References

1-800-PetMeds. (2011). Glyco-Flex Classic - 600 mg. Retrieved June 30, 2011, from 1-800-PetMeds: http://www.1800petmeds.com/Glyco+Flex+Classic+600mg-prod148144.html

Adequan Canine. (2005). FAQ. Retrieved June 30, 2011, from Adequan Canine: http://www.adequancanine.us/about/en/faq.shtml

Granchi, D., Stea, S., Sudanese, A., Toni, A., Baldi, N., & Giunti, A. (2002, Oct).  Association of Two Gene Polymorphisms with Osteoarthritis Secondary to Hip Dysplasia. Retrieved June 30, 2011, from Current Orthopedic Practice: http://journals.lww.com/corr/Abstract/2002/10000/Association_of_Two_Gene_Polymorphisms_With.18.aspx

Hakim, S.M., & Zanchetta, R.J. (2005). Hormones and Healthy Bones. Retrieved June 30, 2011, from ARHP: http://www.arhp.org/uploadDocs/Lactation_and_Bone_Loss.pdf

Kahn, C.M., Line, S., & Merck & Co. (2010). Merck Veterinary Manual. New Jersey: Whitehouse Station.

Karlsson, M., Ahlborg,H., & Karlsson C. (2005). Hormones and Healthy Bones. Retrieved June 30, 2011, from ARHP: http://www.arhp.org/uploadDocs/Lactation_and_Bone_Loss.pdf

Lane, D., & Ewart, N. (1996). A-Z of Dog Disease & Health Problems. New York: Howell Book House.

Orthopedic Foundation for Animals. (2010). The Dysplastic Hip Joint. Retrieved June 30, 2011, from Orthopedic Foundation for Animals: http://www.offa.org/hd_info.html

Orthopedic Foundation for Animals. (2010). The OFA's Hip Radiograph Procedures. Retrieved June 30, 2011, from Orthopedic Foundation for Animals: http://www.offa.org/hd_procedures.html

Plotnick, A. (1999). Canine Arthritis. Retrieved June 21, 2011, from ASPCA: http://www.aspca.org/pet-care/dog-care-canine-arthritis.aspx

Randall, D. (2011). Aspirin for Dogs - Managing Pain & Canine Arthritis. Retrieved June 21, 2011, from Dog Arthritis Aspirin: http://www.dogarthritisaspirin.com/

Rimadyl. (2011). Rimadyl Injectable Overview. Retrieved June 30, 2011, from Rimadyl: http://www.rimadyl.com/display.aspx?drug=RC&species=CN&sec=640

Root Kustritz, M. V. (2007, Dec 1). Determing the Optimal Age for Gonadectomy of Dogs and Cats. Retrieved June 30, 2011, from AVMA: http://www.avma.org/avmacollections/spay_neuter/javma_231_11_1665.pdf

Steinetz, B.G., Williams, A.J., Lust, G., Schwabe, C., Bullesbach, E.E., & Goldsmith, L.T. (2008, Jan 1). Abstract. Retrieved June 30, 2011, from AVMA Journals: http://avmajournals.avma.org/doi/abs/10.2460/ajvr.69.1.59

VetRxDirect. (2011). Cosequin DS Double Strength Chewable for Dogs. Retrieved June 30, 2011, from Vet Rx Direct: http://www.vetrxdirect.com/product/view/cosequin-ds

Zoologist. (2010, May 8). Etodolac. Retrieved June 30, 2011, from Zoo Veterinary: http://zooveterinary.com/veterinary-drugs/etodolac